Global urban environmental change drives adaptation in white clover.

Urbanization transforms environments in ways that alter biological evolution. We examined whether urban environmental change drives parallel evolution by sampling 110,019 white clover plants from 6169 populations in 160 cities globally. Plants were assayed for a Mendelian antiherbivore defense that also affects tolerance to abiotic stressors. Urban-rural gradients were associated with the evolution of clines in defense in 47% of cities throughout the world. Variation in the strength of clines was explained by environmental changes in drought stress and vegetation cover that varied among cities. Sequencing 2074 genomes from 26 cities revealed that the evolution of urban-rural clines was best explained by adaptive evolution, but the degree of parallel adaptation varied among cities. Our results demonstrate that urbanization leads to adaptation at a global scale

Sun-tracking System Design for Parabolic Dish Solar Concentrator

A sun-tracking system design for a 3m diameter Parabolic dish Solar Concentrator is presented. The mechanical design with azimuth-altitude configuration and the developed control algorithm are exhibited. Alignment accuracy and mechanical requirements are studied. A position sensor design is presented, and a system prototype is shown.Fil: Leiva Butti, Juan Manuel. Universidad Nacional de Cuyo. Facultad de Ingeniería; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Rivier, Santiago. Universidad Nacional de Cuyo. Facultad de Ingeniería; ArgentinaFil: Delgado, Lautaro. Universidad Nacional de Cuyo. Facultad de Ingeniería; ArgentinaFil: Rivera, Selva Soledad. Universidad Nacional de Cuyo. Facultad de Ingeniería; ArgentinaFil: Núñez Mc Leod, Jorge Eduardo. Universidad Nacional de Cuyo. Facultad de Ingeniería; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaWorld Congress on Engineering 2018LondresReino UnidoInternational Association of Engineer

The key role of Au-substrate interactions in catalytic gold subnanoclusters

The development of gold catalysis has allowed significant levels of activity and complexity in organic synthesis. Recently, the use of very active small gold subnanoclusters (Au n, n < 10) has been reported. The stabilization of such nanocatalysts to prevent self-aggregation represents a true challenge that has been partially remediated, for instance, by their immobilization in polymer matrices. Here, we describe the transient stabilization of very small gold subnanoclusters (Au n, n < 5) by alkyl chains or aromatic groups appended to the reactive bond of simple alkynes. The superior performance toward Brønsted acid-free hydration of medium to long aliphatic alkynes (1-hexyne and 1-docecyne) and benzylacetylene with respect to phenylacetylene is demonstrated experimentally and investigated computationally. A cooperative network of dispersive Au···C-H and/or Au··· interactions, supported by quantum mechanical calculations and time-resolved luminescence experiments, is proposed to be at the origin of this stabilization. © 2017 The Author(s)