Determination of the Failure Susceptibility of a Flat Die used in Biomass Pelletizing Machines by means of FEA based Design Exploration

This paper focuses on a design analysis of a flat die used in an agricultural biomass pelletizing machine by considering its high pressure loading failure susceptibility. The pellet die is one of the key elements in a pelletizing machine, and the strength of the die plate has an important role on the pellet’s quality and producibility. In fact, higher compression ratio (CR - the ratio of effective length and the internal (press channel) diameter of a die orifice/hole) will provide denser pellets which is a desired phenomenon, however, if the compression pressure is too high or CR is not determined to compensate high pressures, the raw material may block the die and the die may experience deformation failure due to overloading. If the desire is to make high quality pellets with no die failure, optimum flat die hole/orifice design parameters should be used which can provide the best CR for a specific compression pressure. This is the core motivation of this research. In this study, Finite Element Analysis (FEA) based design exploration has been utilised for a sample single hole flat die with various die geometry parameters against various compression pressure values. Following the FEA design exploration undertaken, a response surface analysis (RSA) was carried out and then estimation models (empirical equations), which could be used to calculate parameters of the die hole/orifice against applied compression pressure and failure susceptibility based on structural stress and deformation, was described. The results gained from the RSA has indicated that the estimation models have high R2 values (higher than 98 %) which could be used for adequately predicting failure susceptibility indicators. In addition to this, FEM-based simulation print-outs have provided useful stress distribution visuals on the die against different compression pressure values. Most especially, the study has highlighted that a detailed structural optimisation study may be scheduled in order to obtain die geometry design parameters with a focus on the failure susceptibility

Effect of temperature on embryonic development in sharpsnout seabream (Diplodus puntazzo) eggs

Embryonic development of sharpsnout seabream (Diplodus puntazzo) was studied at eleven water temperatures (two degree intervals from 12 to 32°C). Embryos successfully developed at temperatures of 16-28°C. Cells did not divide at the temperature extremes of 12 and 32°C. Total mortality was observed by the 128 cleavage stage at 14°C and all eggs were dead by the time the embryos extended 2/3 of the internal circumference of the egg at 30°C. There was an inverse relationship between incubation temperature and the rate of embryonic development

Embryonic and larval development of striped sea bream (Lithognathus mormyrus L 1758)

Development of the embryonic and yolk-sac larvae of striped sea bream (Lithognathus mormyrus) was investigated. The average egg and oil globule diameters were 0.71±0.1286 mm and 0.18±0.1344 mm, respectively. The morula, gastrula, and neurula stages, somite formation, and hatching occurred 2:10, 5:15, 8:45, 9:45, and 21:15 hours after fertilization. The total length, yolk- sac volume, oil globule volume, digestive tube length, otolith diameter, head length, eye diameter, preanal and postanal lengths of newly hatched larvae were 1.74±0.03 mm, 0.12±0.008 mm3, 0.003±0.0002 mm3, 0.47±0.02 mm, 54±8 μm, 299±11 μm, 157±8 μm, 911±0.3 μm, and 827±0.03 μm. When the mouth opened 40 h after hatching, these measurements were 2.87±0.014 mm, 0.003±0.001 mm3, 0.001±0.0001 mm3, 0.61±0.015 mm, 134±8 μm, 376±10 μm, 221±13 μm, 1.02±0.03 mm, and 1.84±0.03 mm. During the first 18 hours, the larvae reached 84% of its final total length, the yolk sac was 65% absorbed, and the oil globule was 62% absorbed. Statistical analysis showed negative allometry for the relationships between total length and yolk-sac volume (r2 = 0.88) and total length and oil globule volume (r2 = 0.76), and positive allometry for the relation- ship between total length and digestive tube length (r2 = 0.89)

Effects of Early Weaning on Growth and Digestive Enzyme Activity in Larvae of Sea Bass (Dicentrarchus labrax L.)

The influence of early weaning on digestive enzymes, growth, and survival in sea bass larvae were investigated. Larvae were reared in a closed sea water system and first fed Artemia nau- plii eight days after hatching. Three weaning periods were compared by introducing a micropar- ticulate diet on day 15, 20, or 25. The control continued to be fed only Artemia. The lowest growth and survival rates were obtained in the 15-day group while the highest were in the 25- day group. After weaning, protease activities (trypsin, chymotrypsin, elastase, pepsin) dropped in all groups, indicating malnutrition. Amylase activity slightly increased in all experimental groups due to the higher starch content in the microparticulate diet than in Artemia and the absolute and relative lipid contents were lower in groups fed the microparticulate diet. Lipase activity suddenly dropped after weaning but slightly rose from day 35 until the end of the exper- iment (day 40). Due to decreased larvae development, survival, and digestive enzyme activity, weaning at 20 days after hatching, synchronous to formation of the stomach and enzymatic activity, is strongly recommended

Occupational health and safety in Turkish marine aquaculture

[No Abstract Available

EFFECTS OF DIMETHYL SULFOXIDE (DMSO) AND THAWING RATES ON SPERM MOTILITY FOR CRYOPRESERVATION OF SPERM IN GILTHEAD SEABREAM (SPARUS AURATA)

WOS: 000588493100011The aim of the present study was to establish a protocol for cryopreservation of sperm in Sparus aurata and also to verify the applicability under culture conditions. Cryopreservation of sperm was attempted by using two extenders: Extender A (10 % egg yolk, buffer solution) and Extender B (1% NaCl, 10% BSA Bovine Serum Albumin). Cryoprotectants were assessed at three different concentrations (5, 10 and 15 %, DMSO) individually as well as in combination with varying equilibration times (10 and 30 min). in order to maintain freezing rate, freezing protocols were adjusted by -30 degrees C/min intervals. Obtained results indicated that cryomedium constituting of Extender A with addition of 10% DMSO in dilution ratio of 1:3 (sperm:cryomedium) at an equilibration time of and freezing rate of -30 degrees C/min was more desirable compared to the other experimental procedures (Extender B) that were assessed (P>0.05). Moreover, 40 degrees C for 10 s presented highest post-thaw motility after end of the first month (72,7 +/- 0,35%) (P>0.05). Finally, it is determined that Extender A exhibited better performance in terms of sperm motility, freezing and thawing rate and also this ratio could be effectively utilized for cryopreservation of sperm for this species

Activity of the Digestive Protease, Chymotrypsin, in Larvae of the Cultured Sharpsnout Sea Bream (Diplodus puntazzo)

Specific and total activity of the digestive protease, chymotrypsin, was studied in cultured sharp- snout sea bream larvae (Diplodus puntazzo) for 35 days from hatching and in a variety of pH lev- els. Activity was detected upon hatching (2.8±0.34 mm total length), before the onset of exoge- nous feeding. Specific chymotrypsin activity exponentially increased from mouth opening on day 3 until day 25, then dropped until the end of the experiment. Total chymotrypsin activity sharply increased to day 10, then continued to increase, but slightly, until the end of the experiment. As expected, pH strongly affected both specific and total chymotryptic activity in the digestive tracts of larvae. Both were significantly lower when pH was acidic (1.5, 3.0, 4.0) than when it was alka- line (8.0, 9.0, 10.0) although there were no significant differences within either the acidic or the alkaline range. Our results indicate that chymotrypsin activity is capable of digesting protein before mouth opening and may be a valuable tool for better understanding the nutritional capa- bilities of young larvae