High transverse momentum π0 production by π− and π+ on protons at 280 GeV/c

The inclusive cross sections for π⁰ production by π^? and π⁺ on protons have been measured with a beam momentum of 280 GeV/c using a fine grained electromagnetic calorimeter and the CERN Omega spectrometer. The transverse momentum and Feynmanx _F ranges covered are 4.0<p _T <7.0 GeV/c and ?0.45<x _F <0.6 respectively. The data are compared with leading order QCD calculations.     

On the completion of partial latin squares

In this paper a certain condition on partial latin squares is shown to be sufficient to guarantee that the partial square can be completed, namely, that it have fewer than n entries, and that at most $\text{[}\text{(n + 1)}\text{2}\text{]}$ of these lie off some line, where n is the order of the square. This is applied to establish that the Evans conjecture is true for n ? 8; i.e., that given a partial latin square of order n with fewer than n entries, n ? 8, the square can be completed. Finally, the results are viewed in a conjugate way to establish different conditions sufficient for the completion of a partial latin square.     

Production ofρ +, −, 0 (770),η(550), ω(783) andf 2(1270) mesons in\bar v neon and ν neon charged current interactions

The production of the meson resonances ?(770) (all three charge states), η(550), ω(783) andf ₂(1270) in \(\bar v\) Ne and ν Ne charged current interactions is investigated in a bubble chamber experiment with BEBC at CERN. Except for thef ₂, the main features of resonance production are reasonably well described by the Lund model, although the average resonance multiplicities are overestimated by the model by (67±30)%. The average multiplicities of all resonances, including thef ₂, are well reproduced by a semiempirical model, whose parameters were determined from hadron interaction data.     

Yb(III)-daunomycin interactions. Determination of Nature and number of species by matrix rank analysis

The nature and number of species in Yb(III)-daunomycin solutions have been investigated by graphical and computational methods both of which are based on matrix rank analyses. Determination of the rank of an absorbance matrix, which is the largest non-zero determinant of the matrix, permits the determination of the number of species in solution. The multiple regression analyses performed on the Yb(III)-daunomycin system enabled the determination of the nature of a species that exists at different metal to ligand ratios: ML₂ at ratios less than 1.5, M₂L at ratios greater than 15, and probably predominantly ML in between the two ratios. The matrix rank analyses approach is suited, it was found, to bracket the range of concentration ratios where a particular species predominates. While this is true by and large, it appears that the adequacy of the methods depends on the degree of complexity of the system.     

Methylmercuric halide-halide complexation in ethanol solution

The formation constants for CH₃HgCl₂^? at 26°C (0.31 l/mole), and for CH₃HgBr₂^? at 26°C (0.94 l/mole) and at 60°C (0.70 l/mole) in ethanol solution have been determined from the variation of Hg NMR chemical shift (by INDOR) with composition of methylmercuric halide-lithium halide solutions. These data have been employed in a reexamination of the “one-anion” and “two-anion” catalysed reactions of mercuric bromide with alkylmercuric bromides.     

A strategy for metabolite identification using triple-quadrupole mass spectrometry with enhanced resolution and accurate mass capability

Using a single platform of a triple-quadrupole mass spectrometer equipped with enhanced resolution and accurate mass capabilities, a strategy for metabolite identification of a drug in a biological matrix has been demonstrated. The strategy is based on first screening for metabolites via neutral loss and precursor ion scan schemes, devised as the result of the product ion spectrum of a matrix-free standard of the drug. The accurate masses of the precursor ions identified via the two scan schemes plus the precursor ions of structurally likely metabolites are then determined by enhanced resolution, accurate mass (AM) selected ion monitoring (SIM). The identities of the metabolites are further established by determining the accurate masses of the product ions via enhanced resolution AM selected reaction monitoring (SRM). The feasibility of the strategy was demonstrated using a liver microsome incubation sample of nefazodone, an antidepressant drug. The neutral loss and precursor ion screening runs were able to identify most of the metabolites of nefazodone. The subsequent SIM and SRM experiments gave mass accuracy of better than +/-0.003 u for the masses of the precursor and product ions of nefazodone and all the metabolites. The ability to perform metabolite screening by using the scan features followed by accurate mass determinations on the same instrument is an attractive feature of using a triple-quadrupole mass spectrometer with enhanced resolution and accurate mass capability.     

Insecticidal volatiles from the marigold plant (genustagetes). Effect of species and sample manipulation

Summary Volatiles from three species of the genustagetes, commonly called marigold have been isolated and characterized. Simultaneous steam distillation extractions (SSDE) produced consistently extracts of higher insecticidal activity than Soxhlet extractions. Methylene chloride was the best solvent. Volatiles isolated from theminutae species showed higher activity than those frompatula anderecta. Comparison of extracts from the flower, foliage and roots of the plant showed that most of the activity is located in the flower. The volatiles are highly effective toward both larvae and adult mosquitoes.     

Kinetics of the solvolysis of chloropenta-amminecobalt(III) ions in mixtures of water with t-butyl alcohol or with 2-methoxyethanol

Summary As the transition state for the solvolysis of [Co(NH₃)₅Cl]²⁺ ions is known to have Cl^- ions in a situation closely similar to that in the bulk solvent, the kinetics of this solvolysis have been investigated for comparison in H₂O with added cosolvents of low and high hydrophobicities. A linear variation of log(rate constant) with the reciprocal of the dielectric constant is found with the former, but not with the latter cosolvent. Maxima in the enthalpies and entropies of activation found using the more hydrophobic cosolvent appear at solvent compositions where extrema occur in the physical properties influenced by structural changes in the solvent. The application of a free energy cycle to the solvolysis in H₂O and in the mixtures shows that the emergent solvated cobalt(III) ion in the transition state is more stabilised in the latter than [Co(NH₃)₅Cl]²⁺ with both cosolvents. The application of such a cycle to cases where the initial state is destabilised in the mixture is discussed.