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The Science of Nature - 相似文献
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Kaluzhnaya OV Belikov SI Schröder HC Wiens M Giovine M Krasko A Müller IM Müller WE 《Die Naturwissenschaften》2005,92(3):134-138
In a preceding study it has been reported that the freshwater sponge Lubomirskia baicalensis, living in Lake Baikal (East Siberia), is composed of spicules forming a characteristic pattern which follows radiate accretive growth. Here we report that the spicules are synthesized by the enzyme silicatein, a protein which is related to cathepsin L. The cDNAs for silicatein and the related cathepsin L were isolated and used as probes to show that the mRNA levels of silicatein in the bases of the spicule skeleton of the animals are low, while the mRNA level of cathepsin L in this region exceeds that of the growing zone. This is the first comprehensive study on the importance of the axial filament/silicatein as an essential structural and functional component determining the growth and stability of demosponge spicules.Note: Sequences from Lubomirskia baicalensis have been deposited in the EMBL/GenBank; cDNAs for the putative silicatein (LBSILICA) are deposited under the accession no. AJ786771 and for cathepsin L (LBCATL) under the accession no. AJ786770. 相似文献
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Bergström M 《Journal of Safety Research》2005,36(3):237-240
INTRODUCTION: Measuring the effect of safety and health on production is a difficult value to gauge. METHOD: This article introduces the Potential, which is an instrument for economic analysis that incorporates different changes in conditions. RESULTS: While there are a number of problems associated with methods to determine these calculations, this method is a good indicator of the effects of safety and health and produces more than 300 variables with much less input. IMPACT ON INDUSTRY: Organizations can use this method effectively to determine how safety and health measure can improve their bottom line. A positive business case is highlighted. 相似文献
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Processing and Characterization of Short-Fiber Reinforced Jute/Poly Butylene Succinate Biodegradable Composites: The Effect of Weld-Line 总被引:2,自引:0,他引:2
U.?S.?IshiakuEmail author O.?A.?Khondker S.?Baba A.?Nakai H.?Hamada 《Journal of Polymers and the Environment》2005,13(2):151-157
Fabrication of complex injection molded parts often involves the use of multiple gates. In such situations, polymer melts from different gates meld to form the molded part (weld line). This paper reports on the fabrication and characterization of the mechanical and morphological properties of short fiber reinforced jute/poly butylene succinate (PBS) biodegradable composites. The effect of a dual gated mold in the fabrication of welded specimens was a key focus of the investigation. It was observed that incorporation of jute fiber (10 wt%) conferred drastic changes on the stress–strain properties of the matrix as the elongation at break (EB), dropped from 160% in the matrix to just 10% in the composite. The tensile strength of the composite was lower than that of the matrix. However, it is noteworthy that the tensile modulus of the composite increased. Bending test also revealed that both bending strength and modulus increased with the incorporation of jute. Morphological studies of the tensile fracture surface using SEM revealed two types of failure mode. Ductile failure was indicated by plastic deformation at the initiation of fracture followed by brittle failure. The good interfacial bonding indicated between jute and PBS was attributed to positive interaction between the two polar polymers. A comparison of the non-weld and weld-line samples revealed that the weld-line composites have better mechanical integrity than the corresponding polymer matrix with weld line. The results also revealed that elongation at break and toughness are most sensitive to the presence of the weld-line whereas flexural properties are least sensitive. 相似文献