Comparative effect of Pediococcus acidilactici and Lactococcus lactis on growth performance, survival and enzyme activity of western white leg shrimp (Litopenaeus vannamei)

This study was done in Shahid Kiani Marine Aquaculture Development Center, Choebde, Abadan in order to evaluate the effects of Pediiococcus acidilactici, Lactococcus lactis and vitamin C on growth performance, survival, enzymatic activities and immune responses of L. vannamei during three months. Treatments were included control group, Pediiococcus and Lactococcus treatments which fed with diet containing 1×10P9P cfu gP_1P bacteria and vitamin C. At the end of the experiment, the growth factors, immune parameters, digestive enzymes, intestinal, histology of intestine, carcasses and microbial flora (bacterial total count and lactic acid count) were evaluated. The results indicated that administration of lactobacillus had significant effects on the growth factors as the highest weight, increase specific growth rate, relative growth rate, feed conversion ratio and protein efficiency in the shrimps received pediococcus and then Lactococcus (P<0.05). The best immune function was also observed in the shrimps fed by probiotics, so that proteins and hemoglobin̛ hemolymph, phenoloxidase activity and challenged with V. parahaemolyticus showed a statistical difference comparing to the control group and the group received vitamin C (P<0.05). Some digestive enzymes, in pediococcus treatment showed a significant increase when compared to other treatments (P<0.05). Significant changes in bacterial intestinal flora were observed in probiotic groups compared with control and vitamin C groups (P < 0.05). Histological results showed the positive effects of probiotics in the gut (P < 0.05). While these supplements cannot caused to significant impacts on the shrimp carcass composition (P ˃ 0.05). As a result pediococcus group had the best performance among treatments.

The study and production of fish sauce from Caspian Sea lam fish with traditional fermentation method and microbe and enzyme adding method and identification of important bacteria

Fish sauce is a popular fermented product used in south Asian countries which is made from different small fishes in this research work it was attempted to produce fish sauce from kilka of the Caspian sea, the fish sauce was made from three models of kilka ,such as whole kilka , cooked whole kilka and dressed kilka , each of these models treated it four different fashions of fermentation such as:1- Traditional method, 2- Enzymatic method 3- Microbial method, 4- Mixture of enzyme and microb The results of this investigation showed that time of fermentation for the traditional method was six month, enzymatic method one month, microbial method 3 month and the mixture of enzyme and microb 1 month. The rate of fermentation was least for dressed Kilka, microbial and biochemical changes of Kilka fish sauce were evaluated, total bacterial count was 2.1-6.15 log cfu/ml total volatile nitrogen (TVN) in samples recorded was 250 mg /100g, the amount of protein varied between 10-13 percent, the name of commercial enzymes added was Protamex and Flavourzyme, the bacteria added was L act ob acillus and Pediococous, fish sauce containers fish and 20% salt, temperature of keeping for fermentation was 37 degree c for 6 month.

Collapse mechanism maps for the hollow pyramidal core of a sandwich panel under transverse shear

The finite element method has been used to develop collapse mechanism maps for the shear response of sandwich panels with a stainless steel core comprising hollow struts. The core topology comprises either vertical tubes or inclined tubes in a pyramidal arrangement. The dependence of the elastic and plastic buckling modes upon core geometry is determined, and optimal geometric designs are obtained as a function of core density. For the hollow pyramidal core, strength depends primarily upon the relative density ρ̄ of the core with a weak dependence upon tube slenderness. At ρ̄ below about 3%, the tubes of the pyramidal core buckle plastically and the peak shear strength scales linearly with ρ̄. In contrast, at ρ̄ above 3%, the tubes do not buckle and a stable shear response is observed. The predictions of the current study are in excellent agreement with previous measurements on the shear strength of the hollow pyramidal core, and suggest that this core topology is attractive from the perspectives of both core strength and energy absorption. © 2011 Elsevier Ltd. All rights reserved.

Mechanism of pile group settlement in liquefiable soils

This paper examines the settlement of instrumented 2 × 2 model pile groups in liquefiable soil based on the results of dynamic centrifuge tests. The piles are end-bearing in dense sand, and are instrumented such that base, shaft and total pile load components can be measured. The data suggest that the overall co-seismic group settlement is accrued from incremental settlements of the individual piles as the group rocks under the action of the kinematic and inertial lateral loads. A Newmarkian framework for describing this behaviour is presented in which permanent settlement is incremented whenever the load in any of the piles exceeds the capacity of the soil to support the pile. This bearing capacity of the piles in liquefied soil is estimated based on measured dynamic soil properties during shaking and observations of the changes in load carried by the piles. The contribution of the pile cap in reducing settlement is also discussed. © 2008 ASCE.

Turn-off failure mechanism in large area IGCTs

The destruction mechanism in large area IGCTs (Integrated Gate Commutated Thyristors) under inductive switching conditions is analyzed in detail. The three-dimensional nature of the turn-off process in a 91mm diameter wafer is simulated with a two-dimensional representation. Simulation results show that the final destruction is caused by the uneven dynamic avalanche current distribution across the wafer. © 2011 IEEE.