204 research outputs found

    Opheliidae (Polychaeta) recolectados por el BIO Hero y las campañas del USNS Eltanin en los océanos meridionales y sudamérica

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    Opheliid polychaetes collected by the United States Antarctic Research Program and additional material from South America were made available for study through the Smithsonian Institution, Washington, D.C., USA. The Opheliidae from Antarctic seas were treated by Hartman (1966, 1967, 1978), who summarized earlier work and also described several new species. Of the five genera she recorded, two (Travisia and Kesun) have since been synonymized and one, Ammotrypane, has been referred to Ophelina; Hartman’s records therefore encompass four genera, three of which are represented in the present collections. No representatives of Euzonus (Thoracophelia) were found. The following species were recorded from Antarctica in the present study: Ophelia algida n. sp., Ophelina breviata (Ehlers, 1913), Ophelina cf. cylindricaudata (sensu Hartmann-Schröder and Rosenfeldt, 1989), Ophelina nematoides (Ehlers, 1913), Ophelina scaphigera (Ehlers, 1900), Ophelina cf. setigera (Hartman, 1978), Ophelina syringopyge (Ehlers, 1901), Travisia antarctica Hartman, 1967 (emended 1978), Travisia kerguelensis McIntosh, 1885, Travisia kerguelensis gravieri Monro, 1930, Travisia palmeri n. sp. and Travisia tincta n. sp. The new species of Ophelia is distinguished by having branchiae starting on chaetiger 2 (rather than on or after chaetiger 8 as in most species of this genus). Travisia palmeri has 22 chaetigers and is distinguished by long branchiae. Travisia kerguelensis gravieri is raised to full species status and renamed T. monroi. Travisia tincta n. sp., distinguished by a distinctive Methyl Green staining pattern and long branchiae, is described from off Peru.Los poliquetos ofélidos objeto del presente estudio corresponden al material recolectado por el Programa de Investigación Antártico de los Estados Unidos así como material adicional procedente de Sudamérica. Este material ha sido puestos a disposición de los autores por la Institución Smithsoniana, Washington, D.C., Estados Unidos de América. Los Opheliidae de los mares antárticos fueron previamente estudiados por Hartman (1966, 1967, 1978), quien reunió lo publicado hasta el momento y describió nuevas especies. De los cinco géneros registrados por ella, dos (Travisia y Kesun) han sido desde entonces sinonimizados y uno, Ammotrypane, ha sido incluido en Ophelina. Así, los registros de Hartman incluyen cuatro géneros, tres de los cuales están representados en las colecciones estudiadas. No se han encontrados representantes de Euzonus (Thoracophelia). En el presente estudio se registran las siguientes especies de la Antártida: Ophelia algida n. sp., Ophelina breviata (Ehlers, 1913), Ophelina cf. cylindricaudata (sensu Hartmann-Schröder and Rosenfeldt, 1989), Ophelina nematoides (Ehlers, 1913), Ophelina scaphigera (Ehlers, 1900), Ophelina cf. setigera (Hartman, 1978), Ophelina syringopyge (Ehlers, 1901), Travisia antarctia Hartman, 1967 (enmendada 1978), Travisia kerguelensis McIntosh, 1885, Travisia kerguelensis gravieri Monro, 1930, Travisia palmeri n. sp. y Travisia tincta n. sp. La nueva especie de Ophelia se caracteriza por presentar bránquias a partir del chaetígero 2 (y no a partir del chaetigero 8-11 como ocurre en la mayoria de las especies de este género). Travisia palmeri posee 22 chaetigeros y se caracteriza por sus largas bránquias. Travisia kerguelensis gravieri se eleva a rango de especie y se renombra como T. monroi. Travisia tincta n. sp., caracterizada por sus largas bránquias y un peculiar patrón al ser teñida, se describe de las costas de Perú. &nbsp

    Dip coating process: Silicon sheet growth development for the large-area silicon sheet task of the low-cost silicon solar array project

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    The research program to investigate the technical and economic feasibility of producing solar-cell-quality sheet silicon by dip-coating one surface of carbonized ceramic substrates with a thin layer of large-grain polycrystalline silicon is reported. The initial effort concentrated on the design and construction of the experimental dip-coating facility. The design was completed and its experimental features are discussed. Current status of the program is reported, including progress toward solar cell junction diffusion and miscellaneous ceramic substrate procurement

    Improved detectivity of pyroelectric detectors

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    High detectivity single-element SBN pyroelectric detectors were fabricated. The theory and technology developments related to improved detector performance were identified and formulated. Improved methods of material characterization, thinning, mounting, blackening and amplifier matching are discussed. Detectors with detectivities of 1.3 x 10 to the 9th power square root of Hz/watt at 1 Hz are reported. Factors limiting performance and recommendations for future work are discussed

    Silicon on ceramic process. Silicon sheet growth development for the large-area silicon sheet task of the low-cost silicon solar array project

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    The technical and economic feasibility of producing solar-cell-quality sheet silicon was investigated. The sheets were made by coating one surface of carbonized ceramic substrates with a thin layer of large-grain polycrystalline silicon from the melt. Significant progress was made in all areas of the program

    Dip-coating process: Silicon sheet growth development for the large-area silicon sheet task of the low-cost silicon solar array project

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    The objective of this research program is to investigate the technical and economic feasibility of producing solar-cell-quality sheet silicon by coating one surface of carbonized ceramic substrates with a thin layer of large-grain polycrystalline silicon from the melt. The past quarter demonstrated significant progress in several areas. Seeded growth of silicon-on-ceramic (SOC) with an EFG ribbon seed was demonstrated. Different types of mullite were successfully coated with silicon. A new method of deriving minority carrier diffusion length, L sub n from spectral response measurements was evaluated. ECOMOD cost projections were found to be in good agreement with the interim SAMIS method proposed by JPL. On the less positive side, there was a decrease in cell performance which we believe to be due to an unidentified source of impurities

    Dip coating process: Silicon sheet growth development for the large-area silicon sheet task of the low-cost silicon solar array project

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    To date, an experimental dip-coating facility was constructed. Using this facility, relatively thin (1 mm) mullite and alumina substrates were successfully dip-coated with 2.5 - 3.0 ohm-cm, p-type silicon with areas of approximately 20 sq cm. The thickness and grain size of these coatings are influenced by the temperature of the melt and the rate at which the substrate is pulled from the melt. One mullite substrate had dendrite-like crystallites of the order of 1 mm wide and 1 to 2 cm long. Their axes were aligned along the direction of pulling. A large variety of substrate materials were purchased or developed enabling the program to commence a substrate definition evaluation. Due to the insulating nature of the substrate, the bottom layer of the p-n junction may have to be made via the top surface. The feasibility of accomplishing this was demonstrated using single crystal wafers

    Parameters of state in the global thermodynamics of binary ideal gas mixtures in a stationary heat flow

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    We formulate the first law of global thermodynamics for stationary states of the binary ideal gas mixture subjected to heat flow. We map the non-uniform system onto the uniform one and show that the internal energy U(S∗,V,N1,N2,f1∗,f2∗)U(S^*,V,N_1,N_2,f_1^*,f_2^*) is the function of the following parameters of state: a non-equilibrium entropy S∗S^*, volume VV, number of particles of the first component, N1N_1, number of particles of the second component N2N_2 and the renormalized degrees of freedom. The parameters f1∗,f2∗f_1^*,f_2^*, N1,N2N_1, N_2 satisfy the relation x1f1∗/f1+x2f2∗/f2=1x_1f_1^*/f_1+x_2f_2^*/f_2=1 (f1f_1, where xix_i is the fraction of ii component, and f2f_2 are the degrees of freedom for each component respectively). Thus only 5 parameters of state describe the non-equilibrium state of the binary mixture in the heat flow. We calculate the non-equilibrium entropy S∗S^{*} and new thermodynamic parameters of state f1∗,f2∗f_1^*, f_2^* explicitly. The latter are responsible for heat generation due to the concentration gradients. The theory reduces to equilibrium thermodynamics, when the heat flux goes to zero. As in equilibrium thermodynamics, the steady-state fundamental equation also leads to the thermodynamic Maxwell relations for measurable steady-state properties.Comment: 8 pages, 1 figur

    Origin of attraction between likely charged hydrophobic and hydrophilic walls confining near-critical binary aquaeous mixture with ions

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    Effect of ionic solute on a near-critical binary aqueous mixture confined between charged walls with different adsorption preferences is considered within a simple density functional theory. For the near-critical system containing small amount of ions a Landau-type functional is derived based on the assumption that the correlation, ξ\xi, and the Debye screening length, κ−1\kappa^{-1}, are both much larger than the molecular size. The corresponding approximate Euler-Lagrange equations aresolved analytically for ions insoluble in the organic solvent. Nontrivial concentration profile of the solvent is found near the charged hydrophobic wall as a result of the competition between the short-range attraction of the organic solvent and the electrostatic attraction of the hydrated ions. Excess of water may be present near the hydrophobic surface for some range of the surface charge and ξκ\xi\kappa. As a result, the effective potential between the hydrophilic and the hydrophobic surface can be repulsive far from the critical point, then attractive and again repulsive when the critical temperature is approached, in agreement with the recent experiment [Nellen at.al., Soft Matter {\bf 7}, 5360 (2011)]

    Corner wetting in a far-from-equilibrium magnetic growth model

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    The irreversible growth of magnetic films is studied in three-dimensional confined geometries of size L×L×ML\times L\times M, where M≫LM\gg L is the growing direction. Competing surface magnetic fields, applied to opposite corners of the growing system, lead to the observation of a localization-delocalization (weakly rounded) transition of the interface between domains of up and down spins on the planes transverse to the growing direction. This effective transition is the precursor of a true far-from-equilibrium corner wetting transition that takes place in the thermodynamic limit. The phenomenon is characterized quantitatively by drawing a magnetic field-temperature phase diagram, firstly for a confined sample of finite size, and then by extrapolating results, obtained with samples of different size, to the thermodynamic limit. The results of this work are a nonequilibrium realization of analogous phenomena recently investigated in equilibrium systems, such as corner wetting transitions in the Ising model.Comment: 14 pages, 8 figures. EPJ styl
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