Impact of the surface roughness on the electrical capacitance

A new hybrid approach consists to use the advantages of both systems namely the high geometric aspects of the electrodes of the ultracapacitor and the high dielectric strength of polymer materials used in dielectric capacitors. The surface roughness of the electrodes of the ultracapacitor is manufactured with nano-porous materials; activated carbon and carbon nanotubes (CNTs). Many compositions of both carbonaceous materials are tested with different insulating materials (liquid and solid) to constitute the hybrid capacitor. It appears that the capacitance increases with the carbonaceous composition: An increasing from 15 to 40% is observed as compared to a plane capacitor, it can be twice with a 100 wt% of CNTs content. But, the impregnation of the insulating material in the surface roughness remains the key point of the realization of the hybrid capacitor. The roughness accessibility is a major property to optimize in order to improve the impregnation of the insulating material to increase the electrical capacitance

TRAIT CONVERGENCE AND PLASTICITY AMONG NATIVE AND INVASIVE SPECIES IN RESOURCE-POOR ENVIRONMENTS

Premise of study: Functional trait comparisons provide a framework with which to assess invasion and invasion resistance. However, recent studies have found evidence for both trait convergence and divergence among coexisting dominant native and invasive species. Few studies have assessed how multiple stresses constrain trait values and plasticity, and no study has included direct measurements of nutrient conservation traits, which are critical to plants growing in low-resource environments. Methods: We evaluated how nutrient and water stresses affect growth and allocation, water potential and gas exchange, and nitrogen (N) allocation and use traits among a suite of six codominant species from the Intermountain West to determine trait values and plasticity. In the greenhouse, we grew our species under a full factorial combination of high and low N and water availability. We measured relative growth rate (RGR) and its components, total biomass, biomass allocation, midday water potential, photosynthetic rate, water-use effi ciency (WUE), green leaf N, senesced leaf N, total N pools, N productivity, and photosynthetic N use effi ciency. Key results: Overall, soil water availability constrained plant responses to N availability and was the major driver of plant trait variation in our analysis. Drought decreased plant biomass and RGR, limited N conservation, and led to increased WUE. For most traits, native and nonnative species were similarly plastic. Conclusions: Our data suggest native and invasive biomass dominants may converge on functionally similar traits and demonstrate comparable ability to respond to changes in resource availability

Impacts of drought on plant water relations and nitrogen nutrition in dryland perennial grasses

Background and aims Extensive worldwide dryland degradation calls for identification of functional traits critical to dryland plant performance and restoration outcomes. Most trait examination has focused on drought tolerance, although most dryland systems are water and nutrient co-limited. We studied how drought impacts both plant water relations and nitrogen (N) nutrition. Methods We grew a suite of grasses common to the Intermountain West under both well-watered and drought conditions in the greenhouse. These grasses represented three congener pairs (Agropyron, Elymus, Festuca) differing in their habitat of origin (“wetter” or “drier”). We measured growth, water relations, N resorption efficiency and proficiency and photosynthetic N use efficiency in response to drought. Results Drought decreased growth and physiological function in the suite of grasses studied, including a negative impact on plant N resorption efficiency and proficiency. This effect on resorption increased over the course of the growing season. Evolutionary history constrained species responses to treatment, with genera varying in the magnitude of their response to drought conditions. Surprisingly, habitat of origin influenced few trait responses. Conclusions Drought impacted plant N conservation, although these responses also were constrained by evolutionary history. Future plant development programs should consider drought tolerance not only from the perspective of water relations but also plant mineral nutrition, taking into account the role of phylogeny

Fusarium spp en trigo, capacidad toxicogenica y quimiotaxonomia de las cepas aisladas en la Argentina

Se aislaron e identificaron 91 cepas de Fusarium spp (F graminearum, F equiseti, F moniliforme, F m var anthophilum, F acuminatum, F solani y F oxisporum) a partir de semillas de trigo pan procedentes de 17 localidades trigueras de la República Argentina. Mediante el cultivo de las mismas en arroz pelado y pulido se evaluó la producción de tricotecenos y zearalenona, a los efectos de revelar si existen diferencias regionales en cuanto a su presencia. Se detectaron cepas productoras de tricotecenos del grupo B y zearalenona, no habiéndose hallado productoras del grupo A. De las cepas evaluadas el 82,4% produjeron tricotecenos que se subdividieron en dos grupos: a) las cepas productoras de deoxinivalenol (DON) y su precursor 3 acetil-deoxinivalenol (AcDON) y b) las productoras de nivalenol (NIV) y su precursor 4 acetil-nivalenol o fusarenona-x (FUS-X). Los resultados demostraron que el 48,3% de las cepas fueron productoras de DON, el 7,7% de NIV y el 26,4% tuvieron la capacidad de producir simultaneamente DON y NIV en los cultivos. Al considerar exclusivamente las cepas de F graminearum el 89,4% fueron toxicogénicas, de ellas el 55,9% pertenecieron al quimiotipo DON, 10,3% al quimiotipo NIV y 33,8% produjeron DON y NIV. En cuanto a la zearalenona (ZEA) el 63,2% del total de las cepas fueron productoras de esta toxina, no existiendo ninguna relación entre los grupos DON y NIV con la producción de ZEA. La distribución de las cepas toxicogénicas de Fusarium spp observada en las distintas localidades de la República Argentina, permite inferir la existencia de diferencias regionales en el área triguera.In wheat seeds from 17 different wheat growing sites, 91 Fusarium spp strains (F graminearum, F equiseti, F moniliforme, F m var anthophilum, F acuminatum, F solani and F oxysporum) were isolated and identified. The production of trichothecenes and zearalenone was evaluated after growing them on peeled and polished rice to find out if there were any regional differences in their prevalence. Strains producing trichothecenes of the B group and zearalenone were detected; no producers of the A groups were found. From the strains studied, 82.4% produced trichothecenes, and could be divided into 2 groups: a), deoxynivalenol (DON) producing strains and its precursor 3 acetyldeoxynivalenol (AcDON); and b), nivalenol (NIV) producing strains and its precursor 4 acetylnivalenol or fusarenone-x (FUS-X). The results showed that 48.3% of the strains were DON producers, 7.7% NIV producers and 26.4% produced both DON and NIV. Eighty-nine point four percent Fgraminearum strains were toxigenic; among them 55.9% were DON chemotype, 10.3% NIV chemotype and 33.8% produced DON and NIV. Sixty-three point two percent of the strains also produced zearalenone (ZEA), no relation existing between the DON and NIV groups with regard to ZEA production. The finding of certain toxigenic strains in various sites in Argentina allows us to conclude that regional differences exist