Impact of extreme electrical fields on charge density distributions in Al3Sc alloy

Indexación: Web of Science.In this study, the authors investigated how extreme electrical fields affect charge distribution of metallic surfaces and bond character at the moment of evaporation. The surface structure and neighborhood chemistry were also studied as a function of various field evaporation pathways. Density functional theory (DFT) was used to model the surface bonding and charge distribution and then correlate the DFT results with experimental results by comparing the calculated evaporation fields with atom probe tomography measurements. The evaporation fields of different surface neighborhood chemistries in L1(2)-Al3Sc were calculated, with the Sc atoms occupying the corners of a cubic unit cell and the Al atoms occupying the face centers. Al-Al surface atoms are found via DFT to be more likely to evaporate as dimers because of the Al-Al shared charge density. In contrast, Al-Sc evaporates as single ions due to the increased density localized around the Sc atom. This difference in evaporation behavior correlates with the resistance to degradation under extreme fields. This work allows better interpretation of the atom probe data by clarifying the relationship between different evaporation events and the role of surface and subsurface chemistry. (C) 2016 Author(s).http://avs.scitation.org/doi/10.1116/1.496483

Coordinating institutional approaches to assure sustainable groundwater of adequate quality and quantity in Utah

Utah is an arid state, without the abundant surface water resources enjoyed by states in the humid east. Most precipitation in the state falls in the higher elevations of the Uinta and Wasatch mountains of northern and central Utah. Much of this precipitation ultimately ends up in alluvial deposits at the base of these ranges, from which the vast majority of pumping wells draw their water (Barnes and Croft, 1986). This groundwater is an essential resource for use by the people of Utah. About sixty-three percent of Utah\u27s population is at least partially reliant on groundwater for domestic use. In many rural areas, groundwater is the sole source of water for domestic, irrigation and stock purposes

Evaluation of Three Organic Products With Three Doses for Boat Control (Phytophthora Infestans) in Potato Cultivation (Solanum Tuberosum cv. Fripapa) Riobamba Canton, Chimborazo Province

This research proposes to evaluate three ecological products with three doses for the control disease (Phytophthora infestans) in the potato crop (Solanum tuberosum cv. Fripapa) in the Riobamba canton, Chimborazo province. Three ecological products helped: Citrubact, Fosficarben, and Bioplus in high medium and low doses recommended by the producers, making applications every two weeks in this crop, to determine the best product in both the P. infestans control and performance of growing marginal rate. A design of randomized complete blocks (RCBD) in bifactorial combinations with 9 treatments, 4 replications and a control were used. As a result, the lower incidence of the disease was obtained by Fosficarben treatment in high doses (4cc/Lt) with 8.33%, due to the component ion phosphite, which has a direct effect on the fungal metabolism. The same behaviour was observed in the intensity where Fosficarben in high doses (4cc/Lt) obtained 12,83%, being the lower intensity of the research. The treatment with better performance was also Fosficarben in high doses with 21496, 80l<h/ha. According to the economic analysis the treatment composed by Citrubact in low-doses (lcc/Lt) got a higher marginal rate of return in relation to other treatments of 798.97% and a net income of 2631.28 USD and a variable cost, followed by the Bioplus treatmentdue in medium doses (4cc/Lt) with 765.14% of marginal rate. In conclusion, it is possible to control P. infestans in the potato crop by using ecological products, obtaining a good performance, a healthy product and economic income. Keywords: ecological products, potato crop, control disease. Resumen La presente investigación propone: evaluar tres productos ecológicos con tres dosis para el control de lancha (Phytophthora infestans) en el cultivo de papa (Solanum tuberosum cv. Fripapa) Cantón Riobamba, Provincia de Chimborazo. Ayudándonos de tres productos ecológicos: Citrubact. Fosficarben y Bioplus, en dosis alta media y baja recomendadas por las empresas productoras, realizando aplicaciones cada dos semanas en este cultivo, para determinar el mejor producto, tanto en el control de P. infestans, como en rendimiento del cultivo y tasa de retorno marginal. Se utilizó un diseño de bloques completos al azar (DBCA) en arreglo bifactorial combinatorio, con 9 tratamientos, 4 repeticiones y un testigo. Resultando que la menor incidencia de la enfermedad la obtuvo el tratamiento formado por Fosficarben en dosis alta (4cc/lt) con 8,33%, esto se debe a que contiene ion fosfito, que ejerce un efecto directo sobre el metabolismo fúngico. El mismo comportamiento se pudo observar en la intensidad donde Fosficarben en dosis alta (4cc/lt) obtuvo 12,83% siendo la menor intensidad del estudio. El tratamiento con mayor rendimiento también fue Fosficarben en dosis alta (4cc/lt) con 21496,80 kg/ha. En al análisis económico el tratamiento formado por Citrubact en dosis baja (1 cc/lt) obtuvo una mayor tasa de retorno marginal en relación al resto de tratamientos de 798,97%, con un beneficio neto de 2631,28 USD y un costo variable de 177,55 USD; debido a su dosis baja, es el más rentable de los tratamientos en estudio, seguido por el tratamiento conformado por Bioplus en dosis media (4 cc/lt) con 765,14% de tasa de retorno marginal. En conclusión se puede controlar a P. infestans en el cultivo de papa utilizando productos ecológicos, obteniendo un buen rendimiento, un producto sano y generando ingresos económicos. Palabras clave: productos ecológicos, cosecha de papas, control de enfermedades

The Early Paleozoic history of the Cuyania (greater Precordillera) terrane of western Argentina : evidence from geochronology of detrital zircons from Middle Cambrian sandstones

U-Pb geochronology of large detrital zircons populations is a powerful tool for interpreting sandstone provenance. Here, it is applied to three Middle Cambrian sandstones from the Precordillera of Argentina with the purpose of using the provenance interpretations to test paleogeographic and paleotectonic models proposed for the Cuyania or Precordillera terrane. Two samples from the La Laja Formation have distinctive detrital zircon age distributions. All zircon grains fall within unimodal populations of 1688-1200 Ma in one sample and 1559- 1316 Ma in the other. Of these grains, 23% and 65%, respectively, are within the age range of the North American magmatic gap (1610-1490 Ma), indicating a non-Laurentian provenance. A very different sample was taken from a sandstone interval in a large olistolith within the Estancia San Isidro Formation. Its zircon population is dominated by a single, prominent 615-511 Ma age cluster, which is indicative of a provenance in a Brasiliano orogenic belt. The absence of zircons with Grenvillian ages (1200 to 950 Ma) is difficult to reconcile with paleogeographic and geotectonic models in which Cuyania rifted from Laurentia in Cambrian or Ordovician time. The data are most consistent with models in which Cuyania rifted from the southern margin of West Gondwana. Given a Cambrian association with Gondwana and a post-Ordovician arrival at its present position in Gondwana, the Cuyania terrane must have migrated along the southern and western margins of Gondwana during the Ordovician Period

Superfluid turbulence and pulsar glitch statistics

Experimental evidence is reviewed for the existence of superfluid turbulence in a differentially rotating, spherical shell at high Reynolds numbers (\Rey\gsim 10^3), such as the outer core of a neutron star. It is shown that torque variability increases with \Rey, suggesting that glitch activity in radio pulsars may be a function of \Rey as well. The \Rey distribution of the 67 glitching radio pulsars with characteristic ages $\tau_c \leq 10^6$ {\rm yr} is constructed from radio timing data and cooling curves and compared with the \Rey distribution of all 348 known pulsars with $\tau_c \leq 10^6$ {\rm yr}. The two distributions are different, with a Kolmogorov-Smirnov probability $\geq 1 - 3.9 \times 10^{-3}$. The conclusion holds for (modified) Urca and nonstandard cooling, and for Newtonian and superfluid viscosities

Modelling for potentiometric surface management of multilayer aquifer systems

Assuring the long-term availability of groundwater of adequate quality and quantity frequently requires the implementation of appropriate ground-water and conjunctive water management strategies. Presented is a model for developing optimal strategies for an multilayer aquifer in which stream-aquifer interflow is affected by the potentiometric surface and ground-water use. The model is applied to the Salt Lake Valley. Discussed is the use of pumping to control: l) potential migration of non-point source agricultural contaminants between aquifer layers and 2) the movement of a mile-long plume caused by mining waste