The two-pion-exchange three-nucleon potential and nuclear matter

We derive the complete three-nucleon potential of the two-pion-exchange type, suitable for nuclear structure calculations, by extending away from the forward direction the subthreshold off-pion-mass-shell πN scattering amplitude of Coon, Scadron and Barrett. The off-mass-shell extrapolation, subject to current algebra and PCAC constraints, yields approximately model independent amplitudes (in that they depend primarily on πN data) in the complete potential. The subtraction of the forward propagating nucleon term from the amplitudes is done in greater generality than before. The contribution of this three-nucleon potential to the binding energy of symmetric nuclear matter is estimated using the perturbative formalism of McKellar and Rajaraman. In our treatment of correlations in nuclear matter, the dominant three-nucleon potential has strong components from both s-wave and p-wave πN scattering. A three-body potential based on the p-wave Δ isobar can be considered a special case of the derived potential. Therefore, we are able to trace most of the discrepancies in previously reported binding energy contributions back to the assumed energy denominator in second order. We find the contribution of the three nucleon potential to the energy of symmetric nuclear matter to be ? 1.90 ± 0.2 MeV.     

Large Scale Bioprocess for the Production of Optically Pure <Emphasis Type="Italic">L</Emphasis>-Carnitine

Summary. A competitive production method using the biotransformation of 4-butyrobetaine to enantiomerically pure L-carnitine was developed and scaled-up by Lonza. The process produces L-carnitine in 99.5% yield, and >99.9% enantiomeric excess (ee). Continuous and discontinuous processes were developed but the fed-batch process was found to be economically the most favourable process mode.     

Whole cell matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and in situ structure analysis of streptocidins, a family of tyrocidine-like cyclic peptides

Streptocidins, a family of tyrocidine-like cyclic decapeptides, are an ideal demonstration object for the detection and in situ structure analysis of natural compounds directly in microbial cells using whole cell matrix-assisted laser desorption/ionization time-of-flight-mass spectrometry (MALDI-TOFMS), an emerging technique that can be used for rapid sensitive metabolic profiling of microorganisms. Five main members of the streptocidin family (A-E) were detected in Brevibacillus cells picked from agar plates and identified by in situ structure analysis with post-source decay MALDI-TOFMS. This efficient modern method allows the precise detection of metabolites within minutes without the need to isolate and purify the target compounds. The generated mass spectra are of similar quality to those obtained for the purified peptides. In addition, surface extracts were prepared by treating Brevibacillus cells with 70% acetonitrile in the presence of 0.1% trifluoroacetic acid and fractionated by high-resolution reversed-phase high-performance liquid chromatography (HPLC). In this way ten minor streptocidins were detected demonstrating the full biosynthetic variety of streptocidin production on the cellular level. The streptocidins differ from the well-known tyrocidines essentially in position 3 of the decapeptide chain by replacement of the aromatic amino acid (F/W) found in tyrocidines by L-leucine or L-valine.     

The geometry of rational parameterized representations

We study the projective space of univariate rational parameterized equations of degree d or less in real projective space The parameterized equations of degree less than d form a special algebraic variety We investigate the subspaces on and their relation to rational curves in give a geometric characterization of the automorphism group of and outline applications of the theory to projective kinematics.     

Long-range pair correlations in dilute gases

It is shown that there exist nonequilibrium pair correlations which are not described by the Boltzmann transport equation but which persist even in a dilute gas.     

Precision ground state Hfs-separation of137Ba

High resolution two-photon spectroscopy was applied to investigate isotope shifts of Ssns S₀ Rydberg states of natural strontium in the range 10 ≤ n ≤ 70. While the isotope shifts between the even isotopes 84, 86, and 88 showed no change, a dramatic increase of the shift with increasing principal quantum number was found for the odd isotope Sr-87.     

Isolation and total synthesis of (E)-6, 10-dimethyl-9-methylidene-undec-5-en-2-one,a constituent of Costus root oil

(E)-6, 10-Dimethyl-9-methylidene-undec-5-en-2-one ( 1 ) has been isolated from Costus root oil. A total synthesis of this compound is reported.     

Interferons

Interferons are proteins which bring about a nonspecific and nonimmunological defence reaction against virus infections in vertebrates. Interferon formation is induced in vivo and in vitro by viruses and other agents, e.g. endotoxins, nucleic acids, synthetic anionic copolymers, and phytohemagglutinins. All attempts to produce pure interferons have so far been unsuccessful. Interferons can only exert an antiviral action when the cellular RNA and protein synthesis is intact.     

Polynomials with prescribed zeros on an analytic curve

Recently Totik and Varjú [17] presented an estimate of the uniform norm of a monic polynomial with prescribed zeros on the unit circle. In this paper we improve their estimate and extend it to the case of polynomials with some zeros on an arbitrary analytic curve in the complex plane.