Effect of different concentrations of molasses and forage with Bacillus lechniformis on the growth of Macrobrachium nipponense in vitro

The rearing of juvenile shrimp, Macrobrachium nipponense is of importance in the development of aquaculture, especially by using molasses and Bacillus lechniformis to promote growth. The present study aimed to evaluate the rearing of juvenile shrimp, M. nipponense in laboratory breeding ponds without replacing the water in the presence of B. lechniformis using two strategies: i)  Use of molasses (10=A, 50=B, and 100=C mg) with 1 × 10 ⁸ CFUml-1 B. lechniformis to the ponds, with shrimp in initial weight rates (650.00 ± 68.09, 639.67 ± 74.81, 639.67 ± 67.02) mg and final weight rates (695.67 ± 57.33, 825.00 ± 90.14, 761.33 ± 111.02) mg, ii) Use of feed (100=A, 250-B, and 500=C) mg, with shrimp initial weight rates (107.67 ± 21.94, 106.67 ± 20.82, 103.33 ± 18.93) mg and final weight rates (208.33 ± 16.07, 381.67 ± 36.17, 283.33 ± 15.28) mg. Results of statistical analysis for molasses showed significant differences (p < 0.05) in each daily growth (DG), Specific growth rate (SGR), and no significant differences (p > 0.05) in survival rates. As food conversion ratio (FCR), significant differences (p < 0.05) were found between A and B, contrary to C, which showed no significant differences. There were significant differences (p < 0.05) in DG among A, B, and C in using feed. While SGR showed significant differences (p < 0.05) between A and B but did not have significant differences with C and no significant differences (p > 0.05) in the survival rates.  FCR showed significant differences (p < 0.05) between C and both A and B, which showed no significant difference (p > 0.05) between them. The study will help to reduce the cost and waste of water.     

Measurements of high strain rate properties of polymers using an expanding ring method

Trois polymères d'application ingénieur (HDPE, UHMWPE, et Nylatron GS) ont été étudiés à très grande vitesse de déformation (excédant 104/s). On utilisait une technique d'anneau dilaté, qui nécessite le placement d'un fin anneau de polymère, comme bague glissante autour d'un cylindre/creux ayant les murs épais. Un chargement par onde engendré par un fil explosif, abouti au pulse de pression qui s'exerce sur le mur interne du cylindre. Ce pulse se propage à travers le mur du cylindre et est transféré partiellement dans l'anneau. L'anneau se déplace à une grande vitesse du cylindre presque instantanément et en conséquence décélère sous une tension quasiment uniaxiale dû à la contrainte circonférentielle. L'anneau a été photographié avec un appareil de grande vitesse (des cadres de 105 à 106/s) et on a pris des mesures duquels les vrais propriétés de déformation et de contrainte étaient déterminés. On a comparé les résultats obtenus du barre d'Hopkinson, en conditions quasistatiques avec les expériences de l'anneau dilaté.Three engineering polymers (HDPE, UHMWPE, and Nylatron GS) have been studied at very high tensile strain rates (above 104/s) using an expanding ring technique, which involves placing a thin ring of polymer as a sliding fit around a hollow thick-walled cylinder. A blast wave generated by an exploding wire results in a pressure pulse acting on the internal wall of the cylinder. This pulse propagates through the cylinder wall and is partially transferred into the ring. The ring moves virtually instantaneously at a high velocity away from the cylinder and then decelerates under almost uniaxial tension as a result of the hoop stress. Measurements were made by photographing the ring using a high speed camera at 105 to 106 frames/s, from which the true stress-strain properties were determined. Comparisons have been made between results obtained from quasi static, split Hopkinson pressure bar, and expanding ring experiments

Stress equilibrium effects within Hopkinson bar specimens

Dans le split Hopkinson barre technique pour compréssion, un échantillon en forme de disque serré entre deux fastes barres d'acier est compressé par une impulsion compressive. Les proprietés de la contrainte et déformation de l'échantillon peut être dérivé par la quantité d'impulsion compressive, renvoyé et transmit par l'échantillon, en supposant que l'équilibre contrainte existe tout le long de l'échantillon. Néanmoins pendant la période initiale de compression, les multiples réflexions générés aux deux barre/échantillon interfaces creé une distribution compressive non-uniforme, qui arrive à une évaluation peut-être incorrecte des propriétés initials de contrainte/déformation. Cette publication décrit une analyse de micro-ordinateur afin d'étudier plusieurs paramètres importants qui influencent l'accumulation de l'équilibre contrainte d'élasticité et prédit les formes d'impulsion reflétés et transmit pour des impulsions de compression différents.In the compression testing version of the split Hopkinson pressure bar technique a small disc-shaped specimen, sandwiched between two high-strength steel bars, is compressed by a stress pulse. The stress/strain properties of the specimen can be derived from the amount of the stress pulse reflected and transmitted by the specimen, assuming that stress equilibrium exists throughout the specimen. However, during the initial loading phase the multiple reflections generated at the two specimen/bar interfaces cause a non-uniform stress distribution, leading to possibly inaccurate estimates of the initial stress/strain properties. The paper describes a microcomputer analysis to study many of the important parameters affecting the build-up to elastic stress equilibrium and to predict the reflected and transmitted pulse shapes for different loading pulses