33 resultados para gastropod shell


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Qualitative discrimination criteria are employed commonly to distinguish cultural shell middens from natural shell deposits. Quantitative discrimination criteria remain less developed beyond an assumption that natural shell beds tend to contain a wider range of shell sizes compared to cultural shell middens. This study further tests this assumption and provides the first comparative quantitative analysis of shell sizes from cultural middens, bird middens, and beach shell beds. Size distributions of opercula of the marine gastropod Turbo undulatus within two modern Pacific Gull (Larus pacificus) middens are compared with two Aboriginal middens (early and late Holocene) and two modern beach deposits from southeast Australia. Results reveal statistically significant differences between bird middens and other types of shell deposits, and that opercula size distributions are useful to distinguish Aboriginal middens from bird middens but not from beach deposits. Supplementary qualitative analysis of taphonomic alteration of opercula reveal similar opercula breakage patterns in human and bird middens, and further support previously recognised criteria to distinguished beach deposits (water rolling and bioerosion) and human middens (burning). Although Pacific Gulls are geographically restricted to southern Australia, the known capacity of gulls (Larus spp.) in other coastal contexts around the world to accumulate shell deposits indicates the broader methodological relevance of our study.

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Coffee shell is an environmental concern to china along with steady growth of coffee production. This study attempt to characterize high specific surface area activated carbon (HSSA-AC). HSSA-AC was prepared from carbonized material which obtained from coffee shell by microwave irradiation. Textural properties and surface chemistry of HSSA-AC were found to be strongly depending on the activation time, KOH/C ratio and particle size. The textural properties of the samples were investigated by means of scanning electron microscope analyzer (SEM), cryogenic N2 adsorption, whereas, surface chemistry was probed through Fourier Transform Infrared (FTIR) spectrometer (Maldhure and Ekhe, 2011) and Hydrogen storage performance was tested by H2 adsorption. Maximum surface area of 3149 m2 g−1, Iodine adsorption value 2566 mg/g, Methylene Blue adsorption value 47.5 mL 0.1 g−1, the hydrogen adsorption value 0.91 wt% at 14 MPa and yield 39% was observed in case of microwave treated sample at activation time 9 min, KOH/C ratio 5 and particle size 0.25–0.71 mm. Results revealed usefulness of microwave treatment in influencing surface area of HSSA-AC which could be used in a hydrogen storage material research application.

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A successful trial on preparing natural rubber based core-shell structured fibres by co-axial electrospinning and fabrication of artificial blood vessel scaffolds from crosslinked fibres.