Influence of phenolic acids on growth and inactivation of Oenococcus oeni and Lactobacillus hilgardii

Aims: To determine the effect of several wine-associated, phenolic acids on the growth and viability of strains of Oenococcus oeni and Lactobacillus hilgardii. Methods and Results: Growth was monitored in ethanol-containing medium supplemented with varying concentrations of hydroxybenzoic acids (p-hydroxybenzoic, protocatechuic, gallic, vanillic and syringic acids) and hydroxycinnamic acids (p-coumaric, caffeic and ferulic acids). Progressive inactivation was monitored in ethanolcontaining phosphate buffer supplemented in a similar manner to the growth experiments. Hydroxycinnamic acids proved to be more inhibitory to the growth of O. oeni than hydroxybenzoic acids. On the other hand, some acids showed a beneficial effect on growth of Lact. hilgardii. p-Coumaric acid showed the strongest inhibitory effect on growth and survival of both bacteria. Conclusions: Most phenolic acids had a negative effect on growth of O. oeni, for Lact. hilgardii this effect was only noted for p-coumaric acid. Generally, O. oeni was more sensitive to phenolic acid inactivation than Lact. hilgardii. Significance and Impact of the Study: Eight wine-derived, phenolic acids were compared for their effects on wine lactic acid bacteria. Results indicate that phenolic acids have the capacity to influence growth and survival parameters. The differences found between phenolic compounds could be related to their different chemical structures

D* Production in Deep Inelastic Scattering at HERA

This paper presents measurements of D^{*\pm} production in deep inelastic scattering from collisions between 27.5 GeV positrons and 820 GeV protons. The data have been taken with the ZEUS detector at HERA. The decay channel $D^{*+}\to (D^0 \to K^- \pi^+) \pi^+$ (+ c.c.) has been used in the study. The $e^+p$ cross section for inclusive D^{*\pm} production with $5<Q^2<100 GeV^2$ and $y<0.7$ is 5.3 \pms 1.0 \pms 0.8 nb in the kinematic region {$1.3<p_T(D^{*\pm})<9.0$ GeV and $| \eta(D^{*\pm}) |<1.5$}. Differential cross sections as functions of p_T(D^{*\pm}), $\eta(D^{*\pm}), W$ and $Q^2$ are compared with next-to-leading order QCD calculations based on the photon-gluon fusion production mechanism. After an extrapolation of the cross section to the full kinematic region in p_T(D^{*\pm}) and $\eta$(D^{*\pm}), the charm contribution $F_2^{c\bar{c}}(x,Q^2)$ to the proton structure function is determined for Bjorken $x$ between 2 $\cdot$ 10$^{-4}$ and 5 $\cdot$ 10$^{-3}$.Comment: 17 pages including 4 figure

Observation of Events with an Energetic Forward Neutron in Deep Inelastic Scattering at HERA

In deep inelastic neutral current scattering of positrons and protons at the center of mass energy of 300 GeV, we observe, with the ZEUS detector, events with a high energy neutron produced at very small scattering angles with respect to the proton direction. The events constitute a fixed fraction of the deep inelastic, neutral current event sample independent of Bjorken x and Q2 in the range 3 · 10-4 \u3c xBJ \u3c 6 · 10-3 and 10 \u3c Q2 \u3c 100 GeV2

Aspects complémentaires entre la spectroscopie d'absorption X et la diffraction anomale dans le cas d'entités de taille nanométrique supportés sur un oxyde léger : agrégats métalliques et oxyde de type spinelle

A combined approach based on X-ray Absorption Spectroscopy, classical X-Ray Diffraction and Anomalous Wide Angle X-ray Scattering has been used in the case of nanometer scale metallic particle supported on zeolite and for the supported system "Zn"/Al2O3. For the first material, we report a set of data obtained on a bimetallic PtCo catalyst. Exafs yields information on the local order around platinum before and after the reduction step. Also, diffraction experiments at two energies before the Pt Lm edge are reported and the results obtained from the two techniques are discussed. For the spinel, major information regarding the cation distribution, the electronic state of the metal atoms as well as the size of the zinc based metal oxide clusters are obtained. Through numerical simulations of the modulations of the X-rays absorption coefficient taking into account multiple scattering processes and ab initio calculations of the differential diffraction intensities based on the Debye equation, we have pointed out the fact that the tetrahedral site of the spinel occupied by the zinc atoms are partially occupied.La complémentarité entre deux techniques spécifiques au rayonnement synchrotron, la spectroscopie d'absorption X et la diffraction anomale est illustrée au travers l'étude d'entités de taille nanométrique déposées sur un oxyde léger. En premier lieu, une caractérisation d'agrégats métalliques Pt-Co déposés sur une zéolite montre tous les avantages d'une telle approche. Citons parmi eux, la détermination de la taille de la particule grâce à la connaissance du nombre de premier voisin métallique et de la nature du réseau cristallographique de la particule. Pour les oxydes divisés, cette démarche permet une mesure précise de l'état électronique du zinc, du taux d'occupation des sites tétraédriques ainsi que de la taille du cristallite de l'oxyde étudié