LargeP T P−P collisions to probe the gluonic and sea spin distribution in the proton

We parametrise the polarised gluon and sea distribution functions incorporating the interpretation of the EMC experiment that, due to the axial anomaly the observed quark contribution to proton spin at Q ²>=10.7 GeV². Typical processes to isolate the gluonic and sea content of the proton studied here are the largeP _T direct photon production processes (a) using single polarized protonPPX and (b) polarized beam and target protonPPX. In both the above process the dominant contribution comes from the Compton subprocess and so can be used as a clean probe of the gluonic content of the proton. LargeP _T muon pair production PP(^+–)X are also studied and we find that the annihilation subprocess dominates, but not much larger than the Compton subprocess and so may not be a clean probe of the sea content of the proton. The effect of two loop corrections to the parametrisation and asymmetries are also considered, and are found to be negligible.     

Evaluation of the density matrix for an ensemble of anharmonic oscillators by a path integral approach

Considering the Feynman path integral representation for the configuration-space density matrix for an ensemble of anharmonic oscillators, we determine the stationary paths near which the integrand remains stationary. By taking the path integral to be saturated by contributions from the neighborhood of the path which maximizes the integrand we evaluate the density matrix explicitly in analytic form. This seems to be the first such evaluation of a path integral for a system not describable by a quadratic Hamiltonian. We also comment briefly on the question of analyticity with respect to the perturbation parameter.     

Autocatalytic inactivation of cytochrome p-450 and chloroperoxidase by 1-aminobenzotriazole and other aryne precursors

Cytochrome P-450, as reported previously is inactivated during catalytic turnover of 1-aminobenzotriazole due to alkylation of its prosthetic heme group. NMR analysis of the heme adduct after removal of the iron atom identifies it unequivocally as a derivative of protoporphyrin IX in which two of the nitrogens are bridged by a benzene ring. Cytochrome P-450 destructive activity is retained by analogues with Me or Ac substituents on the exocyclic N but is lost when the N itself is removed or is replaced by a hydroxyl or nitro function. Prosthetic heme alkylation also occurs with 1-amino-1H-naphtho (2,3-d)triazole, the analogue with one additional benzene ring. In vivo studies suggest that 1-aminobenzotriazole is relatively nontoxic. Catalytic turnover of 1-aminobenzotriazole by chloro-peroxidase results in the formation of phenol and in inactivation of the enzyme. The phenol obtained in deuterated water incorporates one deuterium into the aromatic ring. The data indicate that benzyne, formed by enzymatic oxidation of 1-aminobenzotriazole, is responsible for inactivation of cytochrome P-450 and chloroperoxidase.     

THE RELATIONSHIP BETWEEN CAROTENOID PIGMENTS AND RESISTANCE TO RADIATION IN NON-PHOTOSYNTHETIC BACTERIA

Abstract— A radiation-resistant Micrococcus sp. and a colorless mutant subject to gamma radiation were found to have identical killing curves. Similar results were obtained with ultraviolet light. However when exposed to visible light in the presence of the photosensitizer, toluidine blue, the pigmented wild-type was unaffected whereas the colorless mutant was killed. Sarcina lutea and a colorless mutant were killed at similar rates following exposure to x-rays and U.V. light, whereas previous studies have demonstrated that the pigmented wild-type is protected against lethal photosensitizations by visible light. It is concluded that the effect of carotenoid pigments in radiation damage is limited to protecting cells against the lethal effects of visible light and is without effect at shorter wavelengths.     

A study of atomic iodine and molecular thallium iodide by X-ray photoelectron and auger electron spectroscopy

The I3d5/2 binding energy has been measured in atomic iodine, thallium iodide and cesium iodide by high temperature gas-phase photoelectron spectrscopy using Al K (1486.6 eV) X-rays. The iodine M₅N_4,5N_4,5 (¹G₄) Auger energies for TlI and CsI have also been measured and combined with binding energies to yield extra-atomic relaxation energies of 0.5 and O.3 eV, respectively, after corrections are applied to the Auger parameter. Charges were calculated using the simple potential model, which was also used to obtain an estimate of the atomic T14f binding energy. Two other estimates of the atomic T14f7/2 binding energy have also been calculated, both based on Dirac-Fock ΔSCF binding energies. The results of the three methods suggest a value of 125.3 ± 0.2 eV for T14f7/2.     

Asymmetric α-oxyacylation of cyclic ketones

Reaction of cyclic ketones with chiral N-alkyl-O-acyl hydroxylamines leads to the corresponding α-oxyacylated carbonyl compound in up to 89% ee. The levels of asymmetric induction were influenced by solvent polarity, acid strength and, to a lesser extent, temperature. Increasing the steric bulk around the nitrogen atom of the hydroxylamine reagent led to increased levels of asymmetric induction, which was also found to be detrimental to the yield observed for the transformation. Examination of N- and O-substituents along with substrates revealed the scope and limitations of the procedure.