Evaluation of the acetaldehyde production and degradation potential of 26 enological Saccharomyces and non- Saccharomyces yeast strains in a resting cell model system

Acetaldehyde is relevant for wine aroma, wine color, and microbiological stability. Yeast are known to play a crucial role in production and utilization of acetaldehyde during fermentations but comparative quantitative data are scarce. This research evaluated the acetaldehyde metabolism of 26 yeast strains, including commercial Saccharomyces and non-Saccharomyces, in a reproducible resting cell model system. Acetaldehyde kinetics and peak values were highly genus, species, and strain dependent. Peak acetaldehyde values varied from 2.2 to 189.4mgl−1 and correlated well (r 2=0.92) with the acetaldehyde production yield coefficients that ranged from 0.4 to 42mg acetaldehyde per g of glucose in absence of SO2. S. pombe showed the highest acetaldehyde production yield coefficients and peak values. All other non-Saccharomyces species produced significantly less acetaldehyde than the S. cerevisiae strains and were less affected by SO2 additions. All yeast strains could degrade acetaldehyde as sole substrate, but the acetaldehyde degradation rates did not correlate with acetaldehyde peak values or acetaldehyde production yield coefficients in incubations with glucose as sole substrat

Large-eddy simulation of ow and combustion dynamics in a lean partially premixed swirling combustor

A lean partially premixed swirling combustor was studied by resolving the complete flow path from the swirl vanes to the chamber outlet with large-eddy simulation (LES). The flow and combustion dynamics for non-reacting and reacting situations was analysed, where the intrinsic effects of swirl vanes and counter flows on the vortex formation, vorticity distribution for non-reacting cases were examined. A modified flame index was introduced to identify the flame regime during the partially premixed combustion. The combustion instability phenomenon was examined by applying Fourier spectra analysis. Several scalar variables were monitored to investigate the combustion dynamics at different operating conditions. The effects of swirl number, equivalence ratio and nitrogen dilution on combustion dynamics and NOx emissions were found to be significant.This work is supported by the UK EPSRC through Grant EP/K036750/1 and the National Natural Science Foundation of China through Grant No. 51376107. The computation is supported by the Tsinghua National Laboratory for Information Science and TechnologyPeer ReviewedPostprint (author's final draft

Analysis of GT-3a identifies a distinct subgroup of trihelix DNA-binding transcription factors in Arabidopsis

AbstractTrihelix DNA-binding factors (or GT factors) bind to GT elements found in the promoters of many plant genes. Although the binding specificity and the transcriptional activity of some members (e.g. GT-1 and GT-2) have been studied, the regulatory function of this family of transcription factors remains largely unknown. In this work, we have characterised a new GT factor, namely GT-3a, and a closely related member, GT-3b. We show that (1) they can form either homo- or heterodimers but do not interact with GT-1; (2) they are predominantly expressed in floral buds and roots; (3) GT-3a cannot bind to the binding sites of GT-1 or GT-2, but binds to the cab2 and rbcS-1A gene promoters via the 5′-GTTAC sequence, which has been previously shown to be the core of the Site 1 type of GT elements. These results suggest that GT-3a and GT-3b belong to a distinct subgroup of GT factors and that each subgroup of GT factors binds to a functionally distinct type of cis-acting GT elements

A model finding a new Richardson potential with different scales for confinement and asymptotic freedom, by fitting the properties of {\D}^{++} and {\Om}^{-}

Phenomenological Richardson potential has built in asymptotic freedom (AF in short) and confinement, with only one parameter \La in the potential. But it is known that the scales of AF and confinement are not the same. In the present work a relativistic mean field calculation for baryons is tried out with two parameters \La and \La^\prime for AF and confinement respectively .To test the two parameter potential we calculate the energies and the magnetic moments, of the triple u - quark system ({\D}^{++}) and the triple s - quark system ({\Om}^{-}) and found good values for \La=100 MeV and \La^\prime ~= 350 MeV. So we believe that the modified Richardson potential should have AF scale \La ~= 100 MeV and the confinement scale \La^\prime ~= 350 MeV.Comment: Accepted for publication in Nuclear Physics