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  • 1
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 32 (1992), S. 861-867 
    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: Commercial polysulfone/polycarbonate (PSU/PC) polymer blends were reprocessed up to five times to determine the influence that reprocessing has on their structure and physical properties. All the high strain properties, mainly ductility, significantly decreased under harsh processing conditions, such as five cycles at 320°C. The results of reprocessing the blends at 320°C have been compared with results at a lower temperature and also with those of the separate components with the aim of clarifying the origin of the degradation. These results plus Fourier transform infrared spectroscopy (FTIR), dynamic mechanical analysis, and melt flow index measurements (MFI) indicate that the presence of the two polymers together clearly decreases the resistance to degradation of each component. Moreover, degradation under the stated conditions is mainly thermal and does not change the chemical nature of the blends. However, a clear decrease in molecular weight was observed both by viscosimetry and MFI measurements as was a shift to higher temperatures of the low temperature secondary transition of both PC and PSU. Both molecular weight and secondary transition changes usually deteriorate mechanical properties but not in the degree observed here. This probably means that the fine and difficult-to-observe structure of the blend has also changed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 38 (1992), S. 1243-1253 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The degree of hydrogen bonding and macroscopic thermodynamic properties for pure and mixed fluids are predicted with the hydrogen bonding lattice fluid (LFHB) equation of state over a wide range in density encompassing the gas, liquid and supercritical states. The model is successful for molecules forming complex self-associated networks, in this case pure methanol, ethanol, and water, and the mixture 1-hexanol-SF6. In supercritical water, significant hydrogen bonding is still present despite all the thermal energy and is highly pressure- and temperature-dependent. A fundamental description of pressure and temperature effects on hydrogen bonding is presented for a well-defined case, the formation of a complex between a donor and acceptor in an inert solvent, where no self-association is present. The partial molar enthalpy and volume change on complexation both become pronounced near the critical point, where the density is highly variable with temperature and pressure.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 31 (1991), S. 245-252 
    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: A study has been made of property optimization of a composite based on low density polyethylene and polypropylene (PP) blend matrices with talc modified by a titanate coupling agent. Analysis shows that the flexural properties improve with increasing content of both talc and polypropylene. However, the tensile moduli show a different behavior. Tensile strength is hardly affected by the filler content at PP percentages in the matrix above 50 percent. The surface modified talc gives rise to higher mechanical properties than the unmodified talc. This improvement is more noticeable as talc and PP percentages in the composite is increased. Scanning electron microscopy has shown the effect of the coupling agent at the filler/polymer matrix interphase and the greater affinity between talc and polypropylene.
    Additional Material: 13 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Brookfield, Conn. : Wiley-Blackwell
    Journal of Vinyl and Additive Technology 13 (1991), S. 184-186 
    ISSN: 0193-7197
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effect of mixing time, temperature, and thermal treatment on mechanical properties of crosslinked PVC is investigated. The tensile properties and gel content of crosslinked and uncrosslinked PVC molded samples are evaluated. The cured samples exhibited higher tensile strength and thermal stability than unmodified PVC.
    Additional Material: 4 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Brookfield, Conn. : Wiley-Blackwell
    Journal of Vinyl and Additive Technology 13 (1991), S. 160-164 
    ISSN: 0193-7197
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Dry blends of a PVC resin with various plasticizer mixtures were processed at different temperatures to produce samples of different degrees of fusion. The ease of fusion increased with decreasing the solid-gel transition temperature (Tm) of the plasticizer mixture. Nevertheless. Tm was not necessarily a linear function of the individual concentration of plasticizers in the mixture. Therefore, the ease of fusion showed in some cases an optimum at a given concentration of the plasticizer mixture.
    Additional Material: 7 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Brookfield, Conn. : Wiley-Blackwell
    Journal of Vinyl and Additive Technology 14 (1992), S. 74-77 
    ISSN: 0193-7197
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The compatibility of suspension PVC with various plasticizer blends was determined by means of calculated compatibility predictors, such as solubility parameters and polarity parameters, as well as actual measurements of compatibility. Then, with a torque rheometer, the temperature at the fusion peak was obtained for various PVC/plasticizer blend compositions. Finally, empirical equations were derived to relate compatibility parameters with the temperature at the fusion peak, predicting the effect of plasticizer blend on processability.
    Additional Material: 6 Ill.
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  • 7
    Publication Date: 2021-05-19
    Description: In August 1996 acoustic methods were employed to estimate mackerel (Scomber japonicus) abundance in the Buenos Aires, Argentina shelf area of "El Rincón" (4,287 mn2), located between 39°- 40° 30' S. Results showed a biomass estimate of 77,260 t. ASIMRAD EK-500 equipment operated with a 38 KHz split-beam transducer was used. Midwater fishing trawls were employed to identify echotraces and to collect mackerel samples.Trawls 4 and 5 were the most successful. Samples included only adult fish (310-470 mm Lt and ages ranging 2-11). Length and weight growth parameters and mortality rates were estimated. Analysis of the stomach contents revealed that mackerel was feeding exclusively on zooplankters over 2 mmlength. The analysis of the characteristics (dimensions and density) of the mackerel shoals allowed to detect two areas of concentration above and below 40°S latitude. The northern area was characterized by relatively small schools of medium density similar to those of the Mar del Plata area. In the southern zone, large schools of high density that account for almost 92 of the total biomass were found.Differences between both areas were also detected when plankton distribution was analyzed. Higher abundances of the dinoflagellate Alexandrium tamarense corresponded to the southern area. On the contrary, higher zooplankton biomass was detected northerly of 40°S. From an oceanographic standpoint, the presence of mackerel was associated to relatively higher salinity values. As a result of the different data analyzed it is suggested that,during this time of the year, the species shows a migratory pattern from the intermediate shelf to coastal areas.
    Description: Publisher permission
    Description: Published
    Description: Scombridae, Scomber japonicus, caballa, zooplancton, relevamientos ecoicos, condiciones ambientales, biomasa, abundancia, estructura poblacional
    Keywords: Biomass ; Population structure ; Zooplankton ; Environmental conditions ; Abundance ; Biomass ; Population structure ; Zooplankton ; Environmental conditions ; Echo surveys
    Repository Name: AquaDocs
    Type: Journal Contribution
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  • 8
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    Unknown
    Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP)
    Publication Date: 2021-05-19
    Description: Lagrangian changes in distribution and survival within an anchovy egg and larvae patch were studied by means of multiple opening/closing sampling following a free drifting buoy. The buoy was equipped with a radar reflector and flashing light, and it was connected to a current cross drogue floating at 15 m depth, which corresponded to the main egg and larvae concentration within the patch. The drifter was launched on the Buenos Aires continental shelf, off Necochea during the spring spawning peak of 1983. Three discrete depths (within, below and above the thermocline)were repeatedly sampled close to the drogue with a Motoda sampler. Egg and larval abundances in the vicinity of the drogue were monitored at 3/4 hour intervals for a period of three days. Each plankton station included a set of hydrographic and climatological data registered simultaneously. The efficiency of the drogue as a Lagrangian marker was examined by means of the application of multifactorial ANOVA to test the significance of variability between days, light regime, sampling depths, population structure and their interactions. Wind drag on the surface unit did not significantly affect the trajectory of the drogue. Patterns of embryonic and larval vertical distribution are discussed by means of the variations in the centre of mass, in the vertical dispersion and patchiness indexes for each developmental stage analyzed. There is evidence of diel vertical migration in larvae larger than 8 mm SL. Although the incidence of feeding based on observations of the presence of undigested food in the gut content of larvae was low, a daily feeding pattern over a 14-hour period starting after sunrise, was evident. Evening ascent of larger larvae was not related to feeding activity. A single equation two-stage model, assuming age dependent mortality in the embryonic and post-larval period is derived and compared to standard models based on constant exponential decay during each developmental phase.
    Description: Publisher permission
    Description: Published
    Description: Engraulidae, Engraulis anchoita, anchoíta, relevamientos ictioplanctónicos, relevamientos pesqueros, larvas de peces, huevos de peces, distribución vertical, abundancia, boyas a la deriva, efectos ambientales, alimentación, supervivencia, migraciones verticales
    Keywords: Feeding ; Fish larvae ; Survival ; Fish larvae ; Fish eggs ; Vertical migrations ; Feeding ; Environmental effects ; Ichthyoplankton surveys ; Vertical distribution ; Survival ; Abundance ; Drifting data buoys ; Fishery surveys
    Repository Name: AquaDocs
    Type: Journal Contribution
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  • 9
    Publication Date: 2021-05-19
    Description: This paper reviews the information on pelagic and demersal fish eggs and larvae, describing the distribution and seasonality of different species and their arrangement in icthyoplankton assemblages in the Southern patagonian waters. It also reports on 11 surveys conducted by INIDEP during 1992-1995. A total of 488 ichthyoplankton samples were analyzed. Fish eggs have been recognized in 47. of all ichthyoplankton samples. They belong to three species: Coelorhynchus fasciatus, Macrourus whitsoni and Micromesistius australis. Fish larvae of 23 species and 17 families have been identified in 96. of all samples analyzed. Spawning of most species begins in autumn, and progresses through winter, when the southern blue whiting and grenadier fish contribute to more than half of all eggs present in our samples. Nototheniid and myctophiid larvae were caught during all year long. Four larval groups were detected using cluster analysis: the first group, formed exclusively by nototheniids, which occupied a vast area on the continental shelf between 100 and 200 m depth, the second formed by Agonopsis chiloensis, Eleginops maclovinus, Macruronus magellanicus and Sprattus fuegensis in coastal waters, the third formed by myctophiids, Gymnoscopelus spp. and Micromesistius australis, inhabit the outer continental shelf and slope, and the fourth included Protomyctophum spp., Krefftichthys anderssoni and Bathylagus antarcticus, species typically found in Subantarctic waters of the Malvinas Current. Comparing the distribution of eggs and larvae of blue whiting from collections obtained during the 70's and 80's, with those of recent surveys, it is evident, that a significant contraction of the spawning grounds of the species has take place, particularly to the west of the archipelago.
    Description: Sánchez, R.P.; ed. 1999. Reproductive habitat, biology and acoustic biomass estiomates of the southern blue whiting (Micromesistius australis) in the sea off southern patagonia. INIDEP Documento Científico, 5: 93 p.
    Description: Published
    Description: larvas de peces, huevos de peces, distribución estacional, abundancia de asociaciones, ictioplancton
    Keywords: Fish larvae ; Ichthyoplankton ; Fish larvae ; Fish eggs ; Seasonal distribution ; Abundance
    Repository Name: AquaDocs
    Type: Journal Contribution
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  • 10
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    Unknown
    Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero
    Publication Date: 2021-05-19
    Description: Data considered in this paper were obtained during a research cruise carried out on board of RV Dr. E.L. Holmberg from INIDEP (Instituto Nacional de Investigacion y Desarrollo Pesquero) during March-April 2000 in the area between 48°S and 55°S (S Patagonian) region, SW Atlantic. From 61 bottom trawls a total of 355 specimen belonging to 11 skate species were collected. This represents, in number, 1.8 of the total species biomass. All skate species were identified and some biological characteristics for each species analyzed. Abundance was estimated in tons and the distribution area of each species was determined. Total weight and morphometric data by sex were measured total length, disc width and clasper length. Stomach content and macroscopical reproductive conditions were checked in every individual gonads, epididymis, alar thorns, yolk oocytes, oviductal gland and eggs. The most abundant species were: Dipturus chilensis, Bathyraja macloviana, Psammobatis normani, Psammobatis rudis, and Bathyraja magellanica distributed in the whole study area. In lesser abundance Bathyraja brachyurops and Bathyraja albomaculata were present south of 51°S. The other skate species were occasional, with percentages of appearance lower than 1 Amblyraja doellojuradoi, Bathyraja griseocauda, Bathyraja multispinis and Sympterygia bonapartii. Food items in the stomach were identified and cluster analysis was used to characterize feeding preferences. Species were grouped according to feeding habits such as anelidophagous (P.normani, B.macloviana and B.albomaculata), mainly piscivorous (D.chilensis, B.griseocauda and B.brachiurops and to carcinophagous habits P.rudis, B.magellanica, A.doellojuradoi, B.multispinis and S.bonapartii.
    Description: Publisher permission
    Description: Published
    Description: Rajidae, rayas
    Keywords: Feeding behaviour ; Marine fish ; Abundance ; Stomach content ; Food organisms ; Diets ; Feeding behaviour ; Community composition
    Repository Name: AquaDocs
    Type: Journal Contribution
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