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Number of results: 6
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Abstract

The loose, small zooecia of the cheilostome bryozoans have been discovered in the lowermost part of the La Meseta Formation on Seymour (Marambio) Island. They systematically include the representatives of Beanidae Canu et Bassler, Catenicellidae Busk, Savignyellidae Levinsen, and Calwelliidae MacGillivra y. The bryozoan assemblage is comprised of separate, small−sized internal moulds dominated by distinct, boat−shaped zooecia belonging to Beania , scarce, unizooidal internodes tentatively included into a ditaxiporine catenicellid ? Vasignyella , and representative of the family Savignyellidae. A few branched segments composed of multiserial zooecia arranged back to back were tentatively incorporated into ? Malakosaria . Beania , marks the oldest fossil record, whereas representatives of Savignyellidae along with ditaxiporine catenicellid and ? Malakosaria are for the first time reported from Antarctica. The relationship between the taxonomic composition, colony growth−patterns rep− resented by membraniporiform/petraliform, catenicelliform and cellariform, along with associated biota and sedimentary structures of the La Meseta Formation implies nearshore environment, with considerable wave action, and warm climatic conditions.
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Abstract

An additional account on the Oligocene cyclostome Bryozoa has been made from the glaciomarine sediments of the Low Head Member (= Pecten conglomerate of Barton 1965) of the Polonez Cove Formation on King George Island (South Shetland Island, West Antarctica). The following genera have been recognized for the first time in Paleogene of Antarctica: Crista, Bicrisia, Exidmonea, Filisparsa and Mecynoecia. Paleoecological interpretation of the bryozoan assemblage implies that the fauna lived in shallow water at a depth of around 50 m.
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Abstract

Bryozoans were found in upper Cenozoic diamictite debris that crops out at the southwestern tip of Cape Lamb, Vega Island. The diamictite is the youngest deposit on the island and richly composed of foraminifers, brachiopods and scallops. The foraminifera assemblage recovered from the Cape Lamb diamictite and 87 Sr/ 86 Sr isotopic age obtained from the pectinid Adamussium colbecki in the nearby locality of Terrapin indicates a Pleistocene age for this deposit. The main goal of this contribution is to present a bryozoan assemblage of Microporella stenoporta Hayward et Taylor, Hippothoa flagellum Manzoni, Ellisina antarctica (Kluge), Micropora notialis Hayward et Ryland and an indeterminate crisiid constituting the first record of these bryozoan taxa in Cenozoic diamictites of the Antarctic Peninsula.
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Abstract

The effect of cationic, anionic and nonionic surface active additives, organic compounds and polymers on the electrodeposition of Zn-Mo coatings on steel substrate and detailed characterization in chosen optimal conditions was studied. The influence of polyethylene glycol (PEG) various concentration, sodium dodecyl sulphate (SDS), triton X-100, d-sorbitol, cetyl trimethyl ammonium bromide (CTAB), thiourea and disodium ethylenediaminetetraacetate (EDTA) on the electrodeposition process was examined. The composition of deposits was defined by wavelength dispersive X-ray fluorescence spectrometry (WDXRF). Results has shown that the current efficiency of the electrodeposition of Zn-Mo coatings is 71.4%, 70.7%, 66.7% for 1.5 g/dm3 PEG 20000, 0.1 g/dm3 Triton X-100 and 0.75 M D-sorbitol respectively. The surface topography and roughness of selected coatings on steel was investigated by atomic force microscopy (AFM). The attendance of D-sorbitol of 0.75 M in the solution cause clear reduction of grain size and the value of roughness parameter (Ra) in relation to SDS, PEG, Triton X-100 and the sample prepared without the additives. The morphology of electrodeposited layers was studied by scanning electron microscopy (SEM). The addition of selected additives to the electrolytic bath results in the formation of smoother, brighter and more compact Zn-Mo coatings in comparison to layers obtained from similar electrolytes but without the addition of surfactants. The optimal concentration of the most effective additives such as PEG 20000, Triton X-100 and D-sorbitol is 1.5 g/dm3, 0.1 g/dm3, 0.75 M respectively.
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