71,167 research outputs found

    Cooperative catalysis by silica-supported organic functional groups

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    Hybrid inorganic–organic materials comprising organic functional groups tethered from silica surfaces are versatile, heterogeneous catalysts. Recent advances have led to the preparation of silica materials containing multiple, different functional groups that can show cooperative catalysis; that is, these functional groups can act together to provide catalytic activity and selectivity superior to what can be obtained from either monofunctional materials or homogeneous catalysts. This tutorial review discusses cooperative catalysis of silica-based catalytic materials, focusing on the cooperative action of acid–base, acid–thiol, amine–urea, and imidazole–alcohol–carboxylate groups. Particular attention is given to the effect of the spatial arrangement of these organic groups and recent developments in the spatial organization of multiple groups on the silica surface

    BlogForever D2.6: Data Extraction Methodology

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    This report outlines an inquiry into the area of web data extraction, conducted within the context of blog preservation. The report reviews theoretical advances and practical developments for implementing data extraction. The inquiry is extended through an experiment that demonstrates the effectiveness and feasibility of implementing some of the suggested approaches. More specifically, the report discusses an approach based on unsupervised machine learning that employs the RSS feeds and HTML representations of blogs. It outlines the possibilities of extracting semantics available in blogs and demonstrates the benefits of exploiting available standards such as microformats and microdata. The report proceeds to propose a methodology for extracting and processing blog data to further inform the design and development of the BlogForever platform

    Summary of the electromagnetic compatibility evaluation of the proposed satellite power system

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    The effects of the proposed solar power satellite (SPS) operations on electronic equipment and systems by fundamental, harmonic, and intermodulation component emissions from the orbital station; and the fundamental, harmonic, and structural intermodulation emissions from the rectenna site were evaluated. The coupling and affects interactions affecting a wide spectrum of electronic equipment are considered. The primary EMC tasking areas are each discussed separately

    Effect of pig weaning age and commingling after the nursery phase on humoral and behavioral indicators of well-being and on growth performance

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    Two hundred and sixteen pigs were weaned at 14 or 21 d of age to determine the effect of weaning age and commingling after the nursery phase on growth and behavior of pigs in a wean-tofinish facility. Pigs were divided into older and younger age groups and allotted 12 pigs/pen with nine replications of each group. At the end of the nursery phase (d 34 after weaning), one-half of the pigs in each group were removed and commingled for the grower/finisher phase and the other half remained in their original pens. Beginning at weaning (d 0), pigs were monitored via camera surveillance following weaning, commingling, and on d 65 after weaning. While in the nursery phase, older pigs had greater gain and feed intake than younger pigs, however, younger pigs were more efficient throughout the nursery phase than older pigs. Toward the end of the grower/finisher period, younger pigs had greater gain, feed intake, and gain:feed than older pigs and reached a common weight 4 d sooner. Younger pigs spent more time standing or moving during the nursery phase than older pigs. Immediately following commingling, the younger, unmixed pigs spent more time feeding. However on d 65 after weaning, the older, commingled pigs and younger, unmixed pigs spent more time feeding than older, unmixed pigs and younger, commingled pigs. In conclusion, younger pigs grew slower than older pigs during the nursery phase; however, younger pigs gained more during the finishing period. Additionally, weaning age and commingling influenced feeding behavior during the grower/finisher period

    Characteristic frequency of the magnetic radiation of spinor condensates

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    The magnetic radiation of the fully-condensed states of 23^{23}Na condensates have been studied. A narrow characteristic spectral line with a wave length proportional to N^(-2/5) (N is the number of particles) and with a probability of transition proportional to N^(17/5) emitted (absorbed) by the condensate was found. It implies that short wave radiation with a huge probability of transition can be obtained if numerous atoms are trapped. A new technique developed by the authors, namely, the analytical forms of the fractional parentage coefficients, was used to calculate analytically the matrix elements between the total spin-states.Comment: 7 pages, 5 figure

    Fungal Exposure to Meteorite Thin Sections: Developing an Experimental to Observe Biogeochemical Changes

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    The Astromaterials Acquisition & Curation Office maintains collections of meteorite samples collected as part of the Antarctic Search for Meteorites (ANSMET) program. The chief goal of the curation department is to maintain these meteorites in pristine condition. The Astromaterials Research and Exploration Science (ARES) Directorate has implemented a microbial monitoring program for the meteorite collections that has resulted in the isolation of >100 fungal isolates [1], however it is currently unknown if these isolates could present danger to the collections through bioweathering or secretion of organic compounds. We grew a strain of Fusarium oxysporium isolated from nitrogen gas filters feeding the Meteorite Lab nitrogen gas in the presence of a H5 meteorite thin section to determine if this fungus has the capability of altering the mineral structure of this common meteorite. This first trial was to determine and understand the effects of Fusarium oxysporum growth on the iron content within H5 chondrites and evaluate what additional components are needed in the development of future trial runs. This experiment determined new considerations for handling samples, the nature of microscopic scans before and after the incubation period, and the quality of the samples utilized for the experiment. The results of this experiment were promising and warrant further investigation with a more refined process and timeline

    First excited band of a spinor Bose-Einstein condensate

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    The analytical expression of the fractional parentage coefficients for the total spin-states of a spinor N-boson system has been derived. Thereby an S-conserved theory for the spinor Bose-Einstein condensation has been proposed. A set of equations has been established to describe the first excited band of the condensates. Numerical solution for 23^{23}Na has been given as an example.Comment: 6 pages, 3 figure

    Spectral reflectances of natural targets for use in remote sensing studies

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    A collection of spectral reflectances of 156 natural targets is presented in a uniform format. For each target both a graphical plot and a digital tabulation of reflectance is given. The data were taken from the literature and include laboratory, field, and aircraft measurements. A discussion of the different measurements of reflectance is given, along with the changes in apparent reflectance when targets are viewed through the atmosphere. The salient features of the reflectance curves of common target types are presented and discussed
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