Proton spectrum from\bar pd \to 5\pi p at rest and the elementary\bar pnannihilation

We calculate the shape of the proton spectator distribution in \(\bar pd \to 5\pi p\) at low proton momenta. The sensitivity to atomicS- andP-state orbits and to the size of elementarys- andp-wave annihilation is discussed. Implications for the elementary annihilation amplitude \(\bar pn \to 5\pi \) subthreshold are presented.     

Authentication of Honeys of Different Floral Origins via High-Performance Thin-Layer Chromatographic Fingerprinting

JPC – Journal of Planar Chromatography – Modern TLC - This paper explores the high-performance thin-layer chromatographic (HPTLC) fingerprinting of non-sugar constituents for the...     

Dispersion relation analysis of the neutral kaon regeneration amplitude in carbon

We apply a forward dispersion relation to the regeneration amplitude for kaon scattering on C using all available data. The CPLEAR data at low energies allow the determination of the net contribution from the subthreshold region which turns out to be much smaller than earlier evaluations, solving a long standing puzzle. Received: 26 February 1999 / Published online: 15 July 1999     

The reaction γ4He→3Hn π+ in impulse approximation

The reactionγ+⁴He→³H+n+π ⁺ is calculated in the impulse approximation. The influence of nuclear wave functions on the differential cross section is discussed numerically using Gaussian and Irving-Gunn wave functions for the triton and the α-particle. The differences are large enough to be looked for experimentally.     

Electromagnetic Form Factors of Nucleons in a Relativistic Three-Quark Model

We study electromagnetic form factors of nucleons within a relativistic three-quark model with a Gaussian shape for the nucleon-quark vertex. The allowed regions for two adjustable parameters, the range parameter Λ _N in the Gaussian and the constituent quark mass m _q , are obtained from fitting the data for magnetic moments and electromagnetic radii of nucleons. It is found that these observables, when calculated with m _q = 420 MeV and Λ _N = 1.25 GeV, agree very well with the experimental data. For these parameter values, however, our model underestimates the electromagnetic form factors of the nucleon at high momentum transfers for the calculated range O ≤ Q²≤ 1 GeV². Received April 10, 1996; revised June 20, 1996; accepted for publication July 19, 1996     

On the relationship of the scaled phase space and Skyrme-coherent state treatments of proton antiproton annihilation at rest

We discuss pion multiplicities and single pion momentum spectra from proton antiproton annihilation at rest. Both the scaled phase space model and the Skyrmecoherent state approach describe these observables well. In the coherent state approach the puzzling size of the scale parameter relating the phase space integrals for different multiplicities is replaced by a well defined weight function. The strength of this function is determined by the intensity of the classical pion field and its spatial extent is of order 1 fm.     

The inclusive proton spectrum for\bar pd \to 3\pi p at rest re-examined

We re-analyze the spectator proton distribution for ¯pd→π ⁺ π^? π^? p. For this channel previous calculations underestimated the cross section for proton momenta of 300 to 600 MeV/c by about a factor 7 while the channels with higher pion multiplicities and the ¯pd→K¯ Kmπp reactions were well explained. By using detailed experimental information on ¯pn and ¯pp annihilation, meson rescattering can in fact explain the cross section also for the 3π case. The¯ pp annihilation followed by charge exchange pion rescattering is much larger than in the 5π case. Vector meson exchange is small but not negligible at high spectator momenta.     

Biomimetic total synthesis and antimicrobial evaluation of anachelin H

The first biomimetic total synthesis of the iron chelator anachelin H isolated from the cyanobacterium Anabaena cylindrica is reported. A first generation approach delivered one enantiomeric series of the polyketide fragment. Comparison of the 1H NMR data suggested the relative configuration of this anachelin fragment. The relative and absolute configuration of anachelin H was then established by total synthesis. A second generation approach involved the enzymatic conversion of N,N-dimethyltyramine to the anachelin chromophore. It was demonstrated that the enzyme tyrosinase is activated by the product during this reaction, the anachelin chromophore can serve as a tyrosinase activator. Anachelin H was evaluated against a panel of eleven bacterial and fungal pathogens, and moderate antibiotic activity (32 microg/mL) against Moraxella catarrhalis was found.