Impact of N on the atomic-scale Sb distribution in quaternary GaAsSbN-capped InAs quantum dots

The use of GaAsSbN capping layers on InAs/GaAs quantum dots (QDs) has recently been proposed for micro- and optoelectronic applications for their ability to independently tailor electron and hole confinement potentials. However, there is a lack of knowledge about the structural and compositional changes associated with the process of simultaneous Sb and N incorporation. In the present work, we have characterized using transmission electron microscopy techniques the effects of adding N in the GaAsSb/InAs/GaAs QD system. Firstly, strain maps of the regions away from the InAs QDs had revealed a huge reduction of the strain fields with the N incorporation but a higher inhomogeneity, which points to a composition modulation enhancement with the presence of Sb-rich and Sb-poor regions in the range of a few nanometers. On the other hand, the average strain in the QDs and surroundings is also similar in both cases. It could be explained by the accumulation of Sb above the QDs, compensating the tensile strain induced by the N incorporation together with an In-Ga intermixing inhibition. Indeed, compositional maps of column resolution from aberration-corrected Z-contrast images confirmed that the addition of N enhances the preferential deposition of Sb above the InAs QD, giving rise to an undulation of the growth front. As an outcome, the strong redshift in the photoluminescence spectrum of the GaAsSbN sample cannot be attributed only to the N-related reduction of the conduction band offset but also to an enhancement of the effect of Sb on the QD band structure

Water markets in federal countries: comparing coordination institutions in Australia, Spain and the Western USA

Water markets are a form of decentralized resource allocation, yet their success often depends on strong coordination institutions to establish appropriate regulatory frameworks, address disputes and minimize third party impacts as water is redistributed. Water markets and associated institutional reforms are prevalent in countries with federal political systems. The territorial division of authority in federal countries enhances representation of diverse interests and creates incentives for local innovation but it also creates potential coordination challenges in river basins shared by multiple jurisdictions. This paper compares water markets and associated institutional reforms in Australia, Spain and the Western USA - three federations with longstanding experience with water markets but different approaches to distributing authority and intergovernmental coordination in water allocation. We conduct an institutional mapping of national and sub-national roles in market-based water allocation reforms across the three countries and employ process tracing techniques to examine coordination challenges and institutional responses associated with water markets. The comparative institutional analysis illustrates how the policy goals addressed by water markets vary across – and within – the three countries in part due to the level of centralisation and the different balance of national versus sub-national interests driving water market development. Despite these differences, all three cases show that water markets require well-developed inter-governmental coordination institutions, which come in multiple forms matched to the local context, history and specific regional governance challenges

Phenolic composition of Nebbiolo grape (Vitis vinifera L.) from Piedmont: characterization during ripening of grapes selected in different geographic areas and comparison with Uva Rara and Vespolina cv

Grapes (Vitis vinifera L.) are rich in polyphenols; the phenolic composition of grape is very complex and depends on several factors, including grape varieties, ripening stage and pedoclimatic conditions. In this work the amount of total polyphenols, anthocyanins and tannins, the antioxidant activity and the chromatic characteristics of Nebbiolo grapes from Piedmont were determined. Four different cultivation areas and three different ripening stages (starting of veraison, veraison completion and physiological ripeness) were considered. The quantification of individual polyphenols and hydroxycinnamates was performed by RP-HPLC/DAD. In a general way, anthocyanins and flavonols increased during ripening, while antioxidant activity and tannin content remained constant. Differences in specific phenolic composition were observed depending on the sample origin. Nebbiolo samples at different maturity stages were compared among them and with Uva Rara and Vespolina cv: overall Nebbiolo showed the lowest anthocyanin content, evidencing a different profile in respect to the other cultivars (major relative content of peonidin-3-O-glucoside). Multivariate statistical methods (principal components analysis and hierarchical clustering) further permitted recognition of Nebbiolo samples of different geographic origin, particularly those dedicated to \u201cBarolo\u201d winemaking

Yeast Ecology of Wine Production

none2mixedCiani, Maurizio; Comitini, FrancescaCiani, Maurizio; Comitini, Francesc