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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
    Publication Date: 2021-05-19
    Description: The yellowcheek wrasse Haliocheres cyanocephalus (Bloch) is registred by the first time for the Colombian Caribbean. In spite of extensive diving in most reef areas of Colombia since 1980, H. cyanocephalus was observed only in four occasions at the Tayrona Natural Park, the Urabá area, and San Andrés islands. The fish is known to occur in deep waters but in Colombia it was found only in shallow (7-15 m in depth)reef environments. Eight species of the genus Halichoeres are now known from the Colombian Caribbean.
    Description: Published
    Description: Labridae, Halichoeres cyanocephalus
    Keywords: Reef fish
    Repository Name: AquaDocs
    Type: Journal Contribution
    Format: pp.251-255
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  • 4
    Publication Date: 2021-05-19
    Description: Five coral reef areas at the Colombian Caribbean were assessed between 1998 and 2003 through the “National Coral Reef Monitoring System of Colombia” (SIMAC), recording 198 species of fishes. The highest species number was observed in Chengue bay (149), including four new records for the Santa Marta area. At San Andrés Island, 138 species were identified, with nine new records for the Archipelago. At the Rosario Island, 128 species were recorded with eight new records, while 114 species and 12 new records were observed at San Bernardo Islands. Of the 119 fish species recorded at the Urabá area, 48 are reported for the first time.
    Description: Mediante censos visuales se registraron 198 especies de peces asociados a arrecifes coralinos en cinco áreas del Caribe colombiano evaluadas a través del “Sistema Nacional de Monitoreo de Arrecifes Coralinos en Colombia” (SIMAC) entre 1998 y 2003. En la bahía de Chengue se observó el mayor número de especies (149) y cuatro nuevos registros para el área de Santa Marta. En la isla de San Andrés se censaron 138 especies, nueve de las cuales son nuevos registros. En las islas del Rosario se registraron 128 especies con ocho nuevos registros y en las islas de San Bernardo se observaron 114 especies, que incluyen 12 nuevos registros. De las 119 especies reconocidas en Urabá chocoano, 48 son registradas por primera vez para el área.
    Description: Published
    Description: Species list
    Keywords: Coral reefs ; Reef fish ; Coral reefs
    Repository Name: AquaDocs
    Type: Journal Contribution
    Format: pp.101-115
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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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