The aroma glycosides composition of Burgundy Pinot noir must

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Quantum Hall resistance standards from graphene grown by chemical vapor deposition on silicon carbide

Replacing GaAs by graphene to realize more practical quantum Hall resistance standards (QHRS), accurate to within $10^{-9}$ in relative value, but operating at lower magnetic fields than 10 T, is an ongoing goal in metrology. To date, the required accuracy has been reported, only few times, in graphene grown on SiC by sublimation of Si, under higher magnetic fields. Here, we report on a device made of graphene grown by chemical vapour deposition on SiC which demonstrates such accuracies of the Hall resistance from 10 T up to 19 T at 1.4 K. This is explained by a quantum Hall effect with low dissipation, resulting from strongly localized bulk states at the magnetic length scale, over a wide magnetic field range. Our results show that graphene-based QHRS can replace their GaAs counterparts by operating in as-convenient cryomagnetic conditions, but over an extended magnetic field range. They rely on a promising hybrid and scalable growth method and a fabrication process achieving low-electron density devices.Comment: 12 pages, 8 figure

Dielectrophoresis of charged colloidal suspensions

We present a theoretical study of dielectrophoretic (DEP) crossover spectrum of two polarizable particles under the action of a nonuniform AC electric field. For two approaching particles, the mutual polarization interaction yields a change in their respective dipole moments, and hence, in the DEP crossover spectrum. The induced polarization effects are captured by the multiple image method. Using spectral representation theory, an analytic expression for the DEP force is derived. We find that the mutual polarization effects can change the crossover frequency at which the DEP force changes sign. The results are found to be in agreement with recent experimental observation and as they go beyond the standard theory, they help to clarify the important question of the underlying polarization mechanisms

The effect of yeast on the anthocyanin characteristics of fermented model solutions

The sensory quality of red wines is basically determined by the colour, which depends on the amount and on the evolution of anthocyanins and other phenolic compounds extracting from the berries into the wine during wine-making. The anthocyanin-monomers are responsible for the development of the red colour, and their acylated derivatives provide stability for the colour of the wines. The anthocyanin profile of wines is affected by several factors: the grape variety, the conditions during wine-making, and also the yeast culture used for the fermentation. In our experiments a self-compiled model solution was fermented by spontaneous fermentation, as well as by four commercial yeasts under laboratory conditions. After fermentation total polyphenolics, anthocyanins, anthocyanin monomer profile, colour intensity, hue, and the ratio of polymeric anthocyanins were studied. Our results show that the spontaneous yeast fermentation resulted in a higher anthocyanin concentration in the fermented model solution, but the commercial yeast strains provided a more advantageous colour characteristic compared to the spontaneous fermentation. After the spontaneous fermentation less sediment was left than in the commercial yeast fermented samples