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  • 1
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 29 (1989), S. 942-944 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The photochemistry of an appropriately substituted bisimide has been studied in solution by conventional means and time resolved laser techniques as a model for the behavior of inherently photosensitive solvent soluble polyimides, whose photochemistry are not well understood. A mechanism for the photochemical insolubilization of the polymer systems is suggested based on the results for the model system, which is confirmed by time resolved laser studies of polyimide solutions. Phosphorescence quenching rate constants for the model compound indicate that the triplet excited state is about one order of magnitude more reactive than triplet benzophenone, an increase most likely due to the inductive effect of the imide moieties.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0003-3146
    Keywords: polyethylene ; photo-oxidation ; weathering ; mechanism ; kinetics ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The kinetics of the natural and accelerated photo-oxidation of low-denisty polyethylene (LDPE) films have been studied; different geographical locations have been selected for the natural tests, and a range of temperatures used in the accelerated experiments in a specially built temperature-controlled ultraviolet radiation enclosure. A meaningful correlation between natural and accelerated weathering results was established, by means of an adequate superposition of the effects of UV radiation exposure and temperature. Reasonably detailed and accurate, lumped-parameter, kinetic models of the photo-oxidation process have also been developed, to interpret and predict the results of measurements of carbonyl, hydroperoxide and vinyl absorbances as functions of time and temperature; the models predict the general experimental behaviour, and also that both the formation of hydroperoxides and carbonyl Norrish-I reactions are important initiation steps. More complex models have the potential of interpreting other fine details of the degradation behaviour, namely the generation of other chemical species, and the chain scission and cross-linking process which are directly related to changes in the mechanical properties.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 3
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    Unknown
    Santa Marta (Colombia), INVEMAR
    Publication Date: 2021-05-19
    Description: Se describen 20 especies de peces colectados en áreas arrecifales de la costa none de Colombia, de las cuales 19 constituyen primeros registros para este sector del Caribe. Se incluye información sobre aspectos biológicos y ecológicos de las especies.
    Description: 20 species of reef fishes collected in coastal waters of the Colombian Caribbean are described, 19 of which are reponed for thefirst timefor this region. Biológica! and ecological information on these species is given as well.
    Description: Published
    Keywords: Ecology ; Ichthyology ; Marine fish ; New records ; Ichthyology ; Ecology
    Repository Name: AquaDocs
    Type: Journal Contribution
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  • 4
    Publication Date: 2021-05-19
    Description: Se describen 19 especies de peces colectadas en los archipiélagos coralinos de las islas del Rosario y de San Bernardo, las cuales son nuevos registros para el Caribe continental colombiano. Tres de esas especies (Ichthyapus ophioneus, Calamopteryx goslinei y Apogon leptocaulus) no habían sido colectadas antes en el Caribe sur, por lo que estos récords son nuevos para este sector del Mar de las Antillas. Se incluye información sobre aspectos biológicos y ecológicos de las especies.
    Description: 19 species of fishes coliected in the coralline archipelagos of Islas de) Rosario and San Bernardo, which are reponed for the first time for the Colombian continental Car¡bbean, are described. Three of those species (Ichtyapus ophioncus, Calamopteryx goslmei and Apogon leptocaulus) had not been collected before in the southern Caribbean, being therefore new records for this section of the Sea. Biological and ecological information about the 19 species is given as well.
    Description: Published
    Keywords: Fish ; Ecology ; Biology ; Fish ; New records ; Biology ; Ecology
    Repository Name: AquaDocs
    Type: Journal Contribution
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  • 5
    Publication Date: 2021-05-19
    Description: Se presenta información descriptiva y ecológica de nueve especies del género Coryphopterus (Pisces: Gobiidae) colectadas en los arrecifes, principalmente coralinos, del Caribe colombiano (incluyendo la Isla de Providencia). Se incluye además una-clave para identificar las especies. La más común en los muéstreos fue C. personatus (67%), seguida por C. eidolon (52%), C. dicrus (21%), C. glaucofraenum (27%); C. thrix (19%), C. tortugae (10%), C. lipernes (9%), C. hyalinus (4%) y C. alloides (3%). Se observaron diferencias regionales importantes en relación con su presencia y abundancia. Las poblaciones del Caribe continental colombiano tienden a ser más pigmentadas que las de regiones norteñas del Atlántico oeste trópica!, probablemente a causa de la presencia de sedimentos oscuros terrígenos en los fondos arrecifales del sur del Caribe. Los datos preliminares sobre la alimentación de ocho especies sugieren que el género es omnívoro y consume cantidades importantes de detritus, además de variados microinvertebrados. Algunas especies ingieren también algas.
    Description: Descriptive and ecological information on nine species of the gobüd fish genus Coryphopterus, collected mainly in coral reefs of the Colornbian Caríbbean (including Isla de Providencia), ¡s preseníed; a key for species identification is also included. The most common species in the samples was C. personatus (67%), followed by C. eidolon (52%), C. dicrus (27%), C. glaucofraenum (27%), C. thrix (19%), C. tortugae (10%), C. lipernes (9%), C. hyaiinus (4%) and C. alloides (3%); importan! differences in their regional ocurrence and abundance were detectad. Colornbian continental Caríbbean populations tend to be more pigmented than those of northern regions of the tropical western Atlantic, probably because southern Caríbbean reefs have terrígenous dark sedírnents. Preliminary data about the feeding habits of eight species suggest that the genus is omnivorous, eating important amounts of detritus and a variety of microínvertebrates; some species also íngest algae.
    Description: Published
    Description: Coryphopterus
    Keywords: Ecology ; Feeding behaviour ; Ichthyology ; Reef fish ; Ichthyology ; Ecology ; Identification keys ; Abundance ; Feeding behaviour
    Repository Name: AquaDocs
    Type: Journal Contribution
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