Experimental Investigation on Flexural Properties of Natural Fiber and Synthetic Fiber Composites

The use of natural fibers in polymer matrices is highly beneficial because the strength and toughness of these composites resulting are greater than those of the unreinforced plastics. The main objective of present work is to investigate the mechanical properties of BANANA fiber polyester resin composites at different weight fractions and carbon fiber polyester resin composites at different weight fractions. Tested specimens of composites were fabricated according to the standards using hand moulding method. The developed composites were then tested to evaluate their Flexural properties. It was found that the increment in fiber content in composites increases the mechanical properties. The mechanical properties of BANANA fiber composites compared with CARBON fiber composites. However, CARBON based composites exhibited better Flexural properties than BANANA based composites

Relative tolerance of cirripede larval stages to acute thermal shock: A laboratory study

(1) Meroplankters drawn into once-through cooling circuits of coastal power plants are subjected to transient thermal stress. The effect of such acute thermal shock on the development of barnacle larvae was studied in the laboratory. (2) The response of the barnacle larvae (naupliar and cyprid stages) to elevated temperature was dependent on exposure time and their stage of development. (3) Among the stages tested, N-6 larvae showed maximum tolerance. Exposure to 37°C did not affect larval survival, but delayed development of N-2 larva to cypris by one day. (4) Exposure at 40°C delayed, hastened or did not affect the development time of N-2 and N-4 larvae through cypris, depending on exposure time. (5) Ten mins exposure at 43°C proved lethal to all larval stages with mortality ranging from 20 to 86%. (6) Development success of the surviving larvae, measured in terms of cypris yield, showed no significant difference from controls, at temperatures below 40°C. (7) Settlement activity was significantly affected in only those cyprid larvae which were exposed to 43°C for 10 min. (8) Results of the present study indicate that thermal stress experienced in the once-through cooling system does not have significant impact on survival and development of the barnacle larvae at temperatures of 37-40°C. (C) 2000 Published by Elsevier Science Ltd.link_to_subscribed_fulltex

Influence of biofilms on the larval settlement of Balanus reticulatus Utinomi (Cirripedia: Crustacea)

Microbial films, which develop on submerged artificial surfaces, elicit variable responses in settling invertebrate larvae. There is no information on the response of the larvae of the tropical fouling barnacle, Balanus reticulatus to biofilms. Therefore, the influence of biofilms and their components (such as bacteria, diatoms and bacterial exopolymer) on settlement of cyprid larvae of B. reticulatus has been studied. Biofilms significantly reduced larval settlement when compared to clean polystyrene surfaces (control). No significant correlation was found between percentage settlement and biofilm age. Inhibition or induction of settlement was observed, depending on the cell density and growth phase of the bacterial films. Diatom films, regardless of cell density, were inhibitory to cypris settlement. Bacterial exopolymers did not influence settlement at low concentrations (0.001 to 0.0001 %), but inhibited settlement at higher concentrations (0.1 to 0.01%). Our study indicates that presence of natural biofilms and their components such as bacteria, diatoms and bacterial exopolymers on polystyrene render an otherwise attractive surface unsuitable for settlement by larvae of B. reticulatus