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A halophilic bacterium, sp. strain CD6, was isolated from salted fish and its extracellular protease was characterized. Protease production was found to be highest when yeast extract was used as nitrogen source for growth. The protease exhibited stability at wide range of salt concentration (0-12.5%, w/v), temperatures (20-60 °C), and pH (4-10) with maximum activity at 10.0% (w/v) NaCl, 60 °C, pH 7 and 10, indicating its polyextremophilicity. The protease activity was enhanced in the presence of Mg, Mn, Cd, and Al (107-122% relative activity), and with retention of activity > 80% for all of other metal ions examined (K, Ca, Cu, Co, Ni, Zn, and Fe). Both PMSF and EDTA inhibited protease activity, denoting serine protease and metalloprotease properties, respectively. High stability (> 70%) was demonstrated in the presence of organic solvents and detergent constituents, and the extracellular protease from strain CD6 was also found to be compatible in commercial detergents. Proteinaceous stain removal efficacy revealed that crude protease of strain CD6 could significantly enhance the performance of commercial detergent. The protease from sp. strain CD6 could serve as a promising alternative for various applications, especially in detergent industry.

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This study examines the deformation response of CFRP composites with preexisting delamination crack under Mode I loading. A DCB specimen is used in a series of Mode I interlaminar tests, each having a different initial delamination crack length. The 48-ply composite laminate has a symmetric ply sequence with 0/0 fiber orientation at the mid-plane. Apparent toughness is indicated by the composite specimen with a starter film insert, likely due to the presence of a neat pocket of resin at the front of the starter crack. The compliance of pre-delamination cracked specimens increases faster beyond the normalized delamination length, a/L of 0.68 due to effects of severe deflection of the longer DCB specimen arm. The critical energy release rate, GIC = 0.5 N/mm is determined based on pre-cracked DCB specimens. Fractographic analysis revealed a smooth fracture plane that indicates interface delamination as the primary failure mode.

No abstract