Compressive creep of ultrafine grained MgO polycrystals

Steady state compressive creep of ultrafine-grained MgO has been studied in the temperature range 0.3 to 0.38 Tm. The specimens were fabricated by reactive hot pressing i.e. by hot-pressing of Mg(OH)2 during the decomposition reaction, which produced dense specimens (90 % of the theoretical density) with 1 000 Å average grain size. The value of the stress exponent was found to be unity and the activation enthalpy was of the order of 36 kcal/mole.Le fluage stationnaire de l'oxyde de Magnésium polycristallin à grains ultra-fins a été étudié entre 0,3 et 0,38 Tm. Les échantillons ont été fabriqués par frittage réactif durant la réaction de décomposition de Mg(OH)2 . Ce type de frittage produit un matériau dense (90 % de la densité théorique) possédant une taille de grains très fine (1 000 Å). La sensibilité de la vitesse de fluage stationnaire avec la contrainte s'exprime par un exposant de contrainte de l'ordre de l'unité et l'enthalpie d'activation est faible de l'ordre de 36 kcal/mole

Total replacement of fishmeal with poultry by-product meal affected the growth, muscle quality, histological structure, antioxidant capacity and immune response of juvenile barramundi, Lates calcarifer.

The present study investigates if the total replacement of dietary fishmeal (FM) with poultry by-product meal (PBM), supplemented with methionine influences the muscle fatty acids composition, normal gut morphology, histological traits of the liver, muscle, and gill, liver enzymes, immune and antioxidant response, and stress-related gene in juvenile barramundi, Lates calcarifer in relation to growth and feed utilization. Barramundi (3.58±0.01g) were randomly distributed into six 300 L seawater recirculating tanks (25 fish/tank) and fed two formulated isonitrogenous and isolipidic diets for 6 weeks. The control diet had FM as the sole animal protein source, whereas other test diet had only PBM as an animal protein source. Dietary PBM affected the fish performance and feed utilization. Regarding muscle fatty acid profile, total saturated fatty acids and monounsaturated fatty acids elevated while total PUFA particularly n-3 LC-PUFA and EPA decreased in PBM fed fish than control diet fed fish. Liver, muscle, gill, and intestinal histology showed no obvious alteration in control diet fed fish, however, more lipid droplets and hepatic vacuolization in the liver, necrotic myotome in muscle, hyperplasia in secondary lamellae in gill and short and broken folds in the intestine were observed in PBM fed fish. Similar to light microscopy observation of intestinal morphology, the transmission electron microscopy (TEM) analysis revealed shorter and smaller microvilli in fish fed PBM. Histopathological alterations in the liver of PBM fed fish were further associated with the elevated levels of aspartate aminotransferase (AST) and glutamate dehydrogenase (GLDH) and the significant upregulation of stress-related genes, HSP70 and HSP90. Also, a negative influence on lysozyme activity, and antioxidant enzymatic activities were recorded in fish fed PBM. Overall, it can be concluded that a total substitution of FM protein by methionine supplemented PBM negatively influenced the growth performance, liver health, histological traits of different organs, immune and antioxidant response, and expression of stress-related genes in juvenile barramundi

Growth and health of juvenile barramundi (Lates calcarifer) challenged with DO hypoxia after feeding various inclusions of germinated, fermented and untreated peanut meals.

Peanut (Arachis hypogaea) is mainly grown for oil extraction and the remaining oil-free seed referred as peanut meal (PM) leaves with high protein content which can be a possible substitute for fishmeal in aqua-diets. This study evaluates the suitability of three types of processed peanut seeds, namely untreated PM (UPM), fermented PM (FPM), and germinated PM (GPM) from peanut seeds to replace fishmeal in barramundi (Lates calcarifer) diets cultured under a commercial production environment. Nine formulated diets having 3 inclusion levels from the 3 different peanuts (15%, 30% and 60% fishmeal replacement) were evaluated against a control without PM. The performance of various types and levels of PMs was assessed by examining the growth, gut and liver condition and survival of fish after eight weeks of feeding the test diets. The immunological responses of juvenile barramundi were assessed by exposing the fish to the hypoxic conditions for 4 hours. The results showed that fermentation and germination significantly (P<0.05) reduced the tannins and alkaloid contents in the PMs. The fish fed 15% GPM diet grew faster and had higher survival than fish fed control diet, while fish fed diet including 60% GPM showed a significant reduction in growth and survival, and an increase in food conversion rate (FCR). FPM and UPM at any inclusion levels did not alter the growth, survival and FCR. Histology analysis revealed that fish fed 60% GPM and UPM showed higher amount of lipid droplets in liver, myodigeneration in fish muscle and a decrease number of acidic mucins in distal gut compare to all other test diets. Stress caused by reduced dissolved oxygen did not change the sodium, potassium, chlorides and alanine aminotransferase concentrations of plasma of fish fed any diet. However, the stress did increase plasma cortisol significantly (P<0.05) in fish fed 60% GPM, 30% and 60% UPM diets. These results suggest that the PMs can partly replace the fishmeal in juvenile barramundi diet and the processing further improves the PMs quality by reducing its antinutritional factors which in turn can increase either its inclusion level in the barramundi diets or improved growth and health status of the species

Variation in the life-history traits of a Schilbid catfish, Clupisoma garua (Hamilton, 1822) in the coastal waters of southern Bangladesh

For the fi rst time, the present study reports the life-history traits, comprising length-frequency distribution (LFD), sex ratio (SR), length-weight relationships (LWRs), condition factors (CFs), and relative growth ( W R ), of Clupisoma garua in the coastal waters of Bangladesh. A total of 150 specimens ranging from 8.60 to 25.20 cm total length (TL) and 4.26 to 128.80 g body weight (BW) were collected using traditional fi shing gear from August 2013 to July 2014. The overall sex ratio of males to females in the study did not diff er signifi cantly from the expected value of 1:1 ( ? 2 =0.96, P &lt;0.05) but there were signifi cant sex diff erences ( P &lt;0.05) in the intercepts and slopes of graphs characterizing traits in Clupisoma garua . The calculated b values for the LWRs were 2.955, 2.893 and 2.927 for males, females and combined sexes, respectively, and there was negative allometric growth in all cases ( b &lt;3). The condition factors ( K A , K F , K R ) and relative growth ( W R ) also did not diff er signifi cantly ( P &lt;0.05) between the sexes. This study provides a useful tool for fi shery specialists to evaluate the relative condition of fi sh and to initiate early management strategies and regulations for the sustainable management of the remaining stocks of this species in the entire coastal region of southern Bangladesh