1,055 research outputs found

    The [Ne III]/[Ne II] line ratio in NGC 253

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    We present results of the mapping of the nucleus of the starburst galaxy NGC 253 and its immediate surroundings using the Infrared Spectrograph on board the Spitzer Space Telescope. The map is centered on the nucleus of the galaxy and spans the inner 800 × 688 pc^2. We perform a brief investigation of the implications of these measurement on the properties of the star formation in this region using theories developed to explain the deficiency of massive stars in starbursts

    Enhanced ordering reduces electric susceptibility of liquids confined to graphene slit pores.

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    The behaviours of a range of polar and non-polar organic liquids (acetone, ethanol, methanol, N-methyl-2-pyrrolidone (NMP), carbon tetrachloride and water) confined to 2D graphene nanochannels with thicknesses in the range of 4.5 Å to 40 Å were studied using classical molecular dynamics and hybrid density functional theory. All liquids were found to organise spontaneously into ordered layers parallel to the confining surfaces, with those containing polar molecules having their electric dipoles aligned parallel to such surfaces. In particular, monolayers of NMP showed remarkable in-plane ordering and low molecular mobility, suggesting the existence of a previously unknown 2D solid-like phase. Calculations for polar liquids showed dramatically reduced static permittivities normal to the confining surfaces; these changes are expected to improve electron tunnelling across the liquid films, modifying the DC electrical properties of immersed assemblies of carbon nanomaterials.Mexican Council for Science and Technology (CONACyT)This is the final version of the article. It first appeared from Nature Publishing Group via http://dx.doi.org/10.1038/srep2740

    Incidence of particle size distribution in peanut husks bonded panels

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    El propósito de esta etapa de la investigación fue conocer la influencia de la variación del tamaño y de la forma de partículas cáscaras de maní en las propiedades de paneles aglomerados encolados con resina ureica. Se formularon paneles con cáscaras molidas (densidad de las partículas: de 81 Kg/m3), paneles con cáscaras enteras (densidad de las partículas: 200 Kg/m3) y dos combinaciones de las mismas. Los resultados alcanzados demostraron que los paneles compuestos por partículas de cáscaras de maní molidas (finas) mejoraron las propiedades físicas y mecánicas respecto de las placas que incorporaron partículas de mayor tamaño. Los valores de densidad en paneles con partículas molidas fueron 628,67 Kg/m3; absorción de agua 65,3% y 79,75% a 2 h y 24 h respectivamente; e hinchamiento de 9,9% y 14,35% medidos a 2 h y 24 h respectivamente. En relación a la caracterización de propiedades mecánicas de flexión, los valores registrados en muestras elaboradas con partículas finas de cáscaras de maní resultaron en MOR: 3,58 MPa, LOP 2,26 MPa y MOE 627 MPa. Con respecto a tenacidad, el mayor valor fue observado en los tableros elaborados con partículas enteras de cáscaras de maní: 1,58 MPa. Las propiedades caracterizadas se encuentran aun por debajo de las propiedades de las placas comerciales de madera de tipo MDF y aglomerados convencionales. Ajustes al proceso de elaboración de las placas de cáscaras de maní serán incorporados en futuros trabajosThe purpose of this stage was to determine the influence of particle size and shape of peanut husks on the properties of panels made with urea resin. Panels were made with milled husks200 Kg/m3 ) and unmilled husks (81 Kg/m3 ) and two combinations thereof. The results showed that the panels made with milled husks improved physical and mechanical properties with respect to the panels that incorporated unmilled particles. The density values in panels with milled particles were 628.67 Kg / m3 ; water absorption 65.3% and 79.75% at 2 and 24 hours respectively, and swelling of 9.9% and 14.35% measured at 2 and 24 hours respectively. Regarding the characterization of mechanical properties of bending, the values recorded in samples prepared with fine particles of peanut husks resulted in MOR: 3.58 MPa, LOP 2.26 MPa and MOE 627 MPa. With respect to toughness, the highest value was observed in particle boards made from unmilled peanut husks: 1.58MPa. The characterized properties are still below the properties of commercial wood panels. Adjustments to the process of preparing the peanut husks plates will be incorporated in future experiencesFil: Granero, Ana Victoria. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnológico Cordoba. Centro Experimental de la Vivienda Economica(i); ArgentinaFil: Gatani, Mariana Pilar. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnológico Cordoba. Centro Experimental de la Vivienda Economica(i); ArgentinaFil: Medina, J. C. Universidad Nacional de Santiago del Estero. Facultad de Cs.forestales. Instituto de Tecnologia de la Madera; ArgentinaFil: Ruiz, A.. Universidad Nacional de Santiago del Estero. Facultad de Cs.forestales. Instituto de Tecnologia de la Madera; ArgentinaFil: Fiorelli, J.. Universidade de Sao Paulo; Brasil. Laboratorio de Construções e Ambiência. Faculdade de Zootecnia e Enghenaria de Alimentos; BrasilFil: Kreiker, Jeronimo Rafael. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnológico Cordoba. Centro Experimental de la Vivienda Economica(i); ArgentinaFil: Lerda, Maria Josefina. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnológico Cordoba. Centro Experimental de la Vivienda Economica(i); Argentin

    Productivity of three sugarcane cultivars under dry and drip irrigated management

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    O objetivo neste trabalho foi estudar o efeito da tecnologia de irrigação por gotejamento, em cultivares de cana-de-açúcar, em dois ciclos de produção (cana-planta e cana-soca). O delineamento experimental utilizado foi o de blocos ao acaso, com quatro repetições, constituídos pela combinação de três cultivares de cana-de-açúcar: RB867515; RB855536 e SP80-3280, e dois manejos da cultura: sistema de irrigação por gotejamento subterrâneo e sistema de sequeiro, totalizando seis tratamentos. O primeiro ciclo teve duração de 336 dias, ocorrendo precipitação de 1.480 mm. O volume de água disponibilizado pelo sistema de irrigação por gotejamento foi de 400 mm, totalizando 1.880 mm. O segundo ciclo teve duração de 365 dias, cujo volume de água por meio de precipitação foi de 1.394 mm; somados aos 320 mm fornecidos pelo sistema de irrigação, totalizaram 1.714 mm. Ocorreu interação entre manejo e cultivar para as variáveis: produtividade de colmos (TCH) e produtividade de açúcar (TPH) em que a maior diferença foi observada para a cultivar SP80-3280. As cultivares apresentaram respostas diferenciadas na eficiência de utilização da água. No manejo irrigado por gotejamento houve elevação de 24% na produtividade de colmos e de 23% na produtividade de açúcar, em relação ao manejo de sequeiro.This study aimed to evaluate the effect of drip irrigation technology in different sugarcane varieties in two crop cycles (plant cane and ratoon). The experimental design was in completly randomized blocks, in split-plot with four replications, constituted by three sugarcane genotypes: RB867515; RB855536 and SP80-3280 and two crop management: drip irrigation system and rainfed system, totalizing six treatments. The first cycle lasted for 336 days, with rainfall of 1,480 mm. The volume of water provided by the system of drip irrigation was 400 mm, totaling 1,880 mm. The second cycle lasted for 365 days, the volume of water through rainfall was 1,394 mm, added to 320 mm provided by the system of irrigation, totaled 1,714 mm. Interaction between management and cultivars was found significant for the variables: productivity of stalks (TCH) and sugar yield (TPH), in which the largest difference was observed for cultivar SP80-3280. There was significant response to drip irrigation, on average the increase of production of stalks and sugar was 24 and 23%, respectively

    Antarctic geoconservation: a review of current systems and practices

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    The prohibition of commercial mineral resource extraction through the Antarctic Treaty System has removed one significant source of potential damage to Antarctica's geological and geomorphological values. However, given the on-going increase in Antarctic tourism and scientific footprint, some high-quality geological features may be vulnerable to human impact, such as damage due to the construction of logistical facilities, unregulated collection of geological specimens or oversampling for scientific purposes. The Protocol on Environmental Protection to the Antarctic Treaty puts in place a framework for the protection of Antarctica's environmental, scientific, historic, wilderness and aesthetic values. However, the Antarctic Protected Area system is still immature and further implementation of existing management tools may be required to protect the diverse range of vulnerabilities, qualities and spatial scales represented in the geology and geomorphology of the continent. At sites where high-quality mineralogical or palaeontological specimens exist in limited quantities, considerations of how best to prevent oversampling and manage access to remaining material may be supported by assessment of cumulative impacts. Examination of the level of Antarctic specimen loans from a selection of national geological collections suggested that existing publically accessible geological collections could be better utilized, which could reduce environmental impact and oversampling at vulnerable Antarctic sites
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