Natural Hazards - The estimation of design flood is mainly focused on the peak flow and the volume, ignoring the underlying surface factor and flood rising and falling process. Three basic... 相似文献
This paper studies intensively the problems of ship-platform collision.The ship and platformare treated as one structural system connected with spring elements and then motion equation of the colli-sion system is established.A nonlinear force-displacement relationship is derived for the simulation of lo-cal dent in a hit member and the yield surface of a dented tubular section is developed to consider the re-duction of load carrying capacity of hit members.Large deformations,plasticity and strain-hardening ofthe beam-column element are taken into account by combining the elastic large displacement analysis theo-ry with the plastic node method.The effect of the hydrodynamic forces acting on the platform,the rubberfender the property of the local dent and the buckling behavior of beam-column on collision are analyzed.The numerical simulation of the nonlinear dynamic response is carried out by Wilson θ method with updat-ed Newton-Raphson iteration.And the numerical example of the dynamic response of a offs 相似文献
Insulin-like growth factors (IGFs) are key regulators of development and growth. Here, we characterized the igf2 gene from olive flounder (Paralichthys olivaceus) and determined its temporal and spatial expression. We set up an in-vitro protein expression system in eukaryotic human embryonic kidney (HEK293T) cells and explored its effects on cell proliferation. The flounder igf2 cDNA contained a 648-bp open reading frame (ORF) encoding a protein of 215 amino acids (aa), which spanned the complete signal peptide (47 aa), mature peptide (70 aa), and E domain (98 aa). In adult flounder, igf2 mRNA was detected in all selected tissues. In early development, igf2 mRNA was detected throughout development from unfertilized eggs to hatching-stage embryos. In-situ hybridization analysis indicated that igf2 mRNA was specially expressed in the brain region, floor plate, hypochord, otic vesicle, and pectoral fin during embryogenesis. Western blotting analysis indicated that the soluble recombinant flounder IGF2 protein was successfully produced through eukaryotic expression in HEK293T cells. In addition, the recombinant IGF2 protein significantly promoted the proliferation of human cervical carcinoma (HeLa) and HEK293T cells. These results provide new information about the structural and functional conservation, expression patterns, and biological activity of the igf2 in teleosts.
Delineation of bed boundaries based on resistivity logging curves is important prior information for the inversion and interpretation of resistivity logging dat... 相似文献
To explore the polysaccharides from selected seaweeds of Atlantic Canada and to evaluate their potential anti-influenza virus activities, polysaccharides were isolated from several Atlantic Canadian seaweeds, including three red algae (Polysiphonia lanosa, Furcellaria lumbricalis, and Palmaria palmata), two brown algae (Ascophyllum nodosum and Fucus vesiculosus), and one green alga (Ulva lactuca) by sequential extraction with cold water, hot water, and alkali solutions. These polysaccharides were ana-lyzed for monosaccharide composition and other general chemical properties, and they were evaluated for anti-influenza virus activities. Total sugar contents in these polysaccharides ranged from 15.4% (in U. lactuca) to 91.4% (in F. lumbricalis); sulfation level was as high as 17.6% in a polysaccharide from U. lactuca, whereas it could not be detected in an alikali-extract from P. palmaria. For polysaccharides from red seaweeds, the main sugar units were sulfated galactans (agar or carrageenan) for P. lanosa, F. lumbricalis, and xylans for P. palmata. In brown seaweeds, the polysaccharides largely contained sulfated fucans, whereas the polysaccharides in green seaweed were mainly composed of heteroglycuronans. Screening for antiviral activity against influenza A/PR/8/34 (H1N1) virus revealed that brown algal polysaccharides were particularly effective. Seaweeds from Atlantic Canada are a good source of marine polysaccharides with potential antiviral properties. 相似文献