Phenol content of grape skins and the loss of ability to make anthocyanins by mutation

Because berry size varies so much, the total content of phenols extractable from skins can be higher for some varieties with white berries than for some with red. When recalculated as mg of extractable phenol per unit of berry surface, values for representative white Vitis vinifera varieties were invariably lower (0.042--0.122 mg GAE/cm2) and outside the range for representative red varieties (0.132--0.424 mg GAE/cm2). This is discussed as evidence that the mutation losing the ability to make anthocyanins in grapes does not lead to diversion of precursors to other phenols.Der Phenolgehalt in der Haut der Traubenbeere und der Verlust der Anthocyanbildung durch MutationDa die Größe der Traubenbeeren beträchtlichen Schwankungen unterliegt, kann der Gesamtgehalt der aus der Beerenhaut extrahierbaren Phenole - bezogen auf die Einzelbeere oder das Beerengewicht - bei Rebsorten mit weißen Beeren größer sein als bei roten Sorten. Wurden die Phenolgehalte (ausgedrückt als Gallussäure-Äquivalente, GAE) auf die Einheit der Beerenoberfläche bezogen, so lagen die Werte repräsentativer weißer Vitis-vinifera Sorten stets niedriger (0,042-0,122 mg GAE/cm2) und außerhalb des Schwankungsbereiches repräsentativer roter Sorten (0,132-0,424 mg GAE/cm2). Diese Befunde werden dahingehend interpretiert, daß die für den Verlust der Anthocyanbildung verantwortlichen Mutationen nicht auch eine Umwandlung der Präcursoren in andere Phenole nach sich ziehen

Compositional changes in ripening grapes: Caftaric and coutaric acids

Caftaric and coutaric acid contents (juice concentration, amounts per berry, percent of the cis forms) were investigated in samples fully protected from oxidation as ripeness increased in harvests from Grenache, French Colombard and two harvests from different vineyards of Ruby Cabernet Vitis vinifera grapes. Segregation by berry density gave sugar content (ripeness) sequences· free of other variables such as weather and provided berries of nearly identical °Brix at each ripeness level. The two Ruby Cabernet harvests, even though differing considerably in growing conditions and average °Brix level, were much closer in the details of caftaric and coutaric acid compositions to each other than to the other varieties indicating close genetic (varietal) control of these components. The proportion of coutaric to caftaric and the percentage of cis forms tend to rise toward the end of ripening. The overall ripening pattern appears to be that these components are synthesized as the berry enlarges during ripening. If the rate of synthesis is able to keep up with the berry enlargement and the content moderate (French Colombard, Ruby Cabernet), the concentration in juice stays nearly constant at a level typical for the variety. If the content is high (Grenache) and the synthesis does not keep up with berry enlargement, the concentration in juice falls as the berry content rises during ripening, but a relatively high concentration is maintained. Overripe, shriveling berries rise in concentration, but may lose caftaric acid by oxidation if tissue breakdown occurs

A statistical model for the intrinsically broad superconducting to normal transition in quasi-two-dimensional crystalline organic metals

Although quasi-two-dimensional organic superconductors such as $\kappa$-(BEDT-TTF)$_2$Cu(NCS)$_2$ seem to be very clean systems, with apparent quasiparticle mean-free paths of several thousand \AA, the superconducting transition is intrinsically broad (e.g $\sim 1$ K wide for $T_c \approx 10$ K). We propose that this is due to the extreme anisotropy of these materials, which greatly exacerbates the statistical effects of spatial variations in the potential experienced by the quasiparticles. Using a statistical model, we are able to account for the experimental observations. A parameter $\bar{x}$, which characterises the spatial potential variations, may be derived from Shubnikov-de Haas oscillation experiments. Using this value, we are able to predict a transition width which is in good agreement with that observed in MHz penetration-depth measurements on the same sample.Comment: 8 pages, 2 figures, submitted to J. Phys. Condens. Matte

Inadequacies in the conventional treatment of the radiation field of moving sources

There is a fundamental difference between the classical expression for the retarded electromagnetic potential and the corresponding retarded solution of the wave equation that governs the electromagnetic field. While the boundary contribution to the retarded solution for the {\em potential} can always be rendered equal to zero by means of a gauge transformation that preserves the Lorenz condition, the boundary contribution to the retarded solution of the wave equation governing the {\em field} may be neglected only if it diminishes with distance faster than the contribution of the source density in the far zone. In the case of a source whose distribution pattern both rotates and travels faster than light {\em in vacuo}, as realized in recent experiments, the boundary term in the retarded solution governing the field is by a factor of the order of $R^{1/2}$ {\em larger} than the source term of this solution in the limit that the distance $R$ of the boundary from the source tends to infinity. This result is consistent with the prediction of the retarded potential that part of the radiation field generated by a rotating superluminal source decays as $R^{-1/2}$, instead of $R^{-1}$, a prediction that is confirmed experimentally. More importantly, it pinpoints the reason why an argument based on a solution of the wave equation governing the field in which the boundary term is neglected (such as appears in the published literature) misses the nonspherical decay of the field

Caftaric acid in grapes and conversion to a reaction product during processing

Grapes were crushed in the presence of high levels of the anti-oxidants SO2 and ascorbic acid, in an atmosphere deprived of oxygen. Hydroxycinnamic derivatives, particularly caftaric acid in the grape juice were found in much higher amounts than when the usual processing methods were employed.Partial oxidation of caftaric acid is not only very rapid and extensive during unprotected grflpe crushing and juice separation but gives a major reaction product that behaves as a single entity and survives through vinification. It gives a sharp HPLC peak and behaves reciprocally with caftaric, i.e., when caftaric acid in must remains high relative to the berry content the reaction product is low and vice versa. The product appeared identical in all grape varieties tested.The reaction product is about one-sixth as extractable by immiscible solvents as is the parent caftaric acid. It can constitute a large part of the 320 nm absorbance of a wine and explains the variable results and poor yields in attempts to isolate caftaric acid from ordinary wine or juice.L'acide caftarique des raisins et sa conversion en produit de réaction au cours de la vinificationA l'aide de HPLC il a été mis en évidence que l'acide caftarique (caffeoyl tartrique) subit des pertes rapides lors du foulage des raisins dans le cas où ceux-ci ne sont pas complètement protégés contre l'oxidation, comme par ex. foulage en atmosphère inerte en présence d'un niveau élevé de métabisulfite de potassium et d'acide ascorbique. En l'absence de telles précautions les valeurs de la teneur originelle en acide caftarique, considérées comme étant caractéristiques des variétés de vigne, sont douteuses. Des échantillons totalement protégés de 5 variétés blanches et 3 variétés rouges de Vitis vinifera, mûres, se rangent entre 200 mg/l de jus pour Grenache et 50 mg/l pour Carignane. Dans la mesure que l'exposition à l'oxygène et l'activité de phénolase sont évaluables la perte peut être importante. Une majeure partie de cette perte consiste dans un produit de réaction de l'acide caftarique ici pour la première fois décelé (CRP). Ce CRP peut pénétrer dans le vin et sa détermination par HPLC ainsi que celle de l'acide caftarique non transformé montrent, en fonction de la variété de vigne, une grande conversion au cours de la préparation normale du moût. De telles analyses de vins peuvent servir d'indicateurs de l'exposition à l'oxygène au cours de la préparation du moût. La nature du CRP est actuellement étudiée et sa présence peut contribuer à expliquer la faible récupération de l'acide caftarique du moût ou du vin

Estudio preliminar sobre el efecto del ultrasonido en las propiedades fisicoquímicas del vino tinto

Ultrasound is regarded as a potential alternative method for improving the quality of some wines. This study was initiated with the objective of evaluating the effects of ultrasound on some important physicochemical properties of red wine such as chromatic characteristics (CC), electrical conductivity (EC), pH, titratable acidity (TA), total phenolic compounds (TPCs) and DPPH (1,1-diphenyl-2-picryl-hydrazyl) free radical scavenging activity (DFRSA). The operational parameters assessed were ultrasound power, ultrasound frequency, exposure time and bath temperature. Results illustrated that there were significant changes in CC, EC and TPC while pH and TA hardly changed except for samples treated at high temperatures. DFRSA was correlated to TPC during ultrasonic treatment. Application of principal component analysis to the experimental data suggested that exposure time was the factor with the greatest ability to induce changes on wine. Results suggested that ultrasound may be applied to improve some physicochemical properties of red wine.El ultrasonido se considera uno de los métodos alternativos potenciales para mejorar la calidad de algunos vinos. Se comenzó este estudio con el objetivo de evaluar los efectos del ultrasonido en algunas de la propiedades fisicoquímicas importantes del vino tinto como son: las características cromáticas (CC), la conductividad eléctrica (EC), el pH, la acidez (TA), los compuestos fenólicos totales (TPC) y el DPPH (1,1-difenil-2-picrilhidrazil) de actividad de eliminación de radicales libres (DFRSA). Los parámetros operacionales examinados fueron: la potencia de ultrasonido, la frecuencia de ultrasonido, el tiempo de exposición y la temperatura de baño. Los resultados ilustraron la existencia de cambios significativos en CC, EC y TPC, mientras que el pH y TA prácticamente no cambiaron excepto en las muestras tratadas con altas temperaturas. DFRSA tuvo correlación con TPC durante el tratamiento con ultrasonido. La aplicación de análisis de componentes principales a los datos experimentales sugirió que el tiempo de exposición era el factor con mayor habilidad para inducir cambios en el vino. Los resultados sugirieron que el ultrasonido podría aplicarse para mejorar algunas de las propiedades fisicoquímicas del vino tinto.National Natural Science Foundation of China [No. 31101324]Natural Science Foundation of Shaanxi Province, China [No. 2015JM3097]Technology Transfer Promotion Project of Xi’an, Shaanxi Province, China [No.CXY1434(5)]Fundamental Research Funds for the Central Universities of China [Nos. GK201302039, GK201404006

Are rodent population eruptions in southeast Asia associated with quantity or quality of food?

Htwe, N.M., Singleton, G.R., Sluydts, V., Hinds, L.A

The magnetoresistance and Hall effect in CeFeAsO: a high magnetic field study

The longitudinal electrical resistivity and the transverse Hall resistivity of CeFeAsO are simultaneously measured up to a magnetic field of 45T using the facilities of pulsed magnetic field at Los Alamos. Distinct behaviour is observed in both the magnetoresistance Rxx({\mu}0H) and the Hall resistance Rxy({\mu}0H) while crossing the structural phase transition at Ts \approx 150K. At temperatures above Ts, little magnetoresistance is observed and the Hall resistivity follows linear field dependence. Upon cooling down the system below Ts, large magnetoresistance develops and the Hall resistivity deviates from the linear field dependence. Furthermore, we found that the transition at Ts is extremely robust against the external magnetic field. We argue that the magnetic state in CeFeAsO is unlikely a conventional type of spin-density-wave (SDW).Comment: 4 pages, 3 figures SCES2010, To appear in J. Phys.: Conf. Ser. for SCES201

On the relation between Unruh and Sokolov--Ternov effects

We show that the Sokolov--Ternov effect -- the depolarization of particles in storage rings coming from synchrotron radiation due to spin flip transitions -- is physically equivalent to the Unruh effect for circular acceleration if one uses a spin 1/2 particle as the Unruh--DeWitt detector. It is shown that for the electron, with gyromagnetic number $g \approx 2$, the exponential contribution to the polarization, which usually characterizes the Unruh effect, is "hidden" in the standard Sokolov-Ternov effect making it hard to observe. Thus, our conclusions are different in detail from previous work.Comment: 23 pages, no figure