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Search Results: 1 - 10 of 26 matches for " Piyapong CHOTIPUNTU "
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Effects of Planktonic Food Organisms on Fatty Acid Composition of Penaeus monodon Fabricius Larvae
Piyapong CHOTIPUNTU
Walailak Journal of Science and Technology , 2004, DOI: 10.2004/vol1iss1pp71-79
Abstract: Penaeus monodon larvae at the first mysis stage were reared to the first post larval stage (PL-1) in 1-L lmhoff cones on three different diets: rotifers enriched with Pavlova lutheri (Rp), rotifers enriched with a commercial micro-encapsulated diet (Re), and a mixture of P. lutheri and Artemia salina nauplii (PA). The 14 essential fatty acids in the larvae that received the three different diets were measured and compared. Profiles of the fatty acids in the larvae and diets were also described. Fatty acid composition of the larvae resembled that of the diets. The total fatty acid per dry weight of larvae was higher in larvae fed PA than that of larvae fed Rp or Re (p<0.01). The highest levels of the four major essential fatty acids – 18:2(n-6), 18:3(n-3), 20:5(n-3), and 22:6(n-3) – were found in the larvae that received Re, PA, and Rp respectively. There was no significant difference in survival rates (86.7 - 92.5%) of the larvae receiving different diets (p>0.05). The fatty acid composition of the larvae fed a mixture of Pavlova and Artemia resembled that found in Artemia but not in Pavlova.
Marine Diatom (Chaetoceros calcitrans) as a Monospecies Diet for Conditioning Oyster (Crassostrea belcheri Sowerby) Broodstock
Piyapong CHOTIPUNTU
Walailak Journal of Science and Technology , 2005, DOI: 10.2004/vol2iss2pp201-207
Abstract: Chaetoceros calcitrans is a marine diatom widely used in aquaculture industries, as it is comprised of nutritional value suitable for most marine filter feeders. Large amounts of the diatom cells are routinely discharged from shrimp hatcheries as uneaten food. The effluent, rich in algal cells, can potentially be re-used to feed oyster broodstock, as the oysters are an effective filter feeder. This study attempted to investigate viability of C. calcitrans as a monospecies diet for conditioning broodstock of Crassostrea belcheri. It was found that gametes of both sexes developed to spawning condition when rearing in captivity using C. calcitrans. Gametes were found in all four stages i.e. active, ripe, spawned and spent - at 15.4, 30.8, 30.8 and 23.1%, respectively when reared for 20 days. When the conditioning period was extended for 40 days, the development stages were found at 15.4, 15.4, 30.8 and 38.5%, respectively. The whole body weight decreased 2.01-2.65% after 20 days and 7.72% after 40 days. The condition indices were obtained between 6.31-7.78% and showed no relation to gametogenic stages of gonad. This study concluded that C. calcitrans can potentially be used as a monospecies diet for conditioning of oysters C. belcheri broodstock.
Aquaculture Potential of Climbing Perch, Anabas Testudineus, in Brackish Water
Piyapong CHOTIPUNTU,Piyathap AVAKUL
Walailak Journal of Science and Technology , 2010, DOI: 10.2004/vol7iss1pp15-21
Abstract: Climbing perch, Anabas testudineus, is a freshwater fish species commercially grown in Southeast Asian countries. This study investigated aspects of salinity on hatching viability and growth performance of climbing perch to use as a measure for aquaculture in brackish water. The experiments were carried out under controlled laboratory conditions. The hormonal induction spawned eggs, and farm reared fry fish of an average body weight of 1.51 - 1.54 g were used in this study. The tested media were prepared using fresh seawater diluted with dechlorinated supplied tap water. It was found that hatching rates for the artificially fertilized eggs were 77 - 92 % in salinities of 0 - 4.5 ppt. The LC50 (24 h) was found to be 5.1 ppt. Hatching was not observed in salinities higher than 7.5 ppt. When fry were reared in different salinities for 40 days, they were found to grow best in salinity of 6.9 ppt. Normal growth rates were found in salinities up to 10.2 ppt. The fry stopped growing and gradually died off in salinities higher than 12.4 ppt. This study suggests that brackish water can potentially be used for climbing perch aquaculture. Saline water up to 4 ppt is practical for propagation of the fish. The fry climbing perch may be nurtured in brackish water of 6 - 7 ppt to obtain the best growth performance.
Urea as a Nitrogen Source in a Black Tiger Shrimp (Penaeus monodon) Closed Culture System
Supannee SUWANPAKDEE,Sataporn DIREKBUSARAKOM,Piyapong CHOTIPUNTU,Putth SONGSANGJINDA
Walailak Journal of Science and Technology , 2010, DOI: 10.2004/vol7iss2pp135-140
Abstract: Urea [(NH2)2CO] is an organic compound that serves an important role in the metabolism of nitrogen-containing compound by animals. Urea is widely used in aquaculture systems. This study investigated the effects of urea on growth of Penaeus monodon. Shrimp were reared in 500 l fiber tanks. There was no exchange of water throughout the experiment. Shrimp with an average body weight of 10.99 ± 0.19 g were stocked at a density of 32 shrimp/m2 in 20 ppt diluted seawater and fed with 38 % protein diet for 9 weeks. Urea was added into the culture tanks at a concentration of 1.25 ppm once a week. The results show that urea slightly affects growth and survival of shrimp. Shrimp reared in the culture pond with added urea had a marginal better growth rate (p > 0.05) while the survival rate was significantly higher than the control group (p < 0.05). The urea in the closed culture tanks was shown to reduce the toxicity of ammonia in soil and promoted growth of plankton communities. Adding urea has no effect on water quality. This study concluded that urea is a potential nitrogen source in closed culture systems when the nitrogen input through the feeding regime is limited. It suggests that urea should be added at a concentration of 1.25 ppm once a week into culture systems with limiting nitrogen sources.
A characterization of M?bius transformations
Piyapong Niamsup
International Journal of Mathematics and Mathematical Sciences , 2000, DOI: 10.1155/s0161171200010255
Abstract: We give a new invariant characteristic property of Möbiustransformations.
Dynamics of Newton's functions of Barna's polynomials
Piyapong Niamsup
International Journal of Mathematics and Mathematical Sciences , 2002, DOI: 10.1155/s0161171202010475
Abstract: We define Barna's polynomials as real polynomials with all real roots of which at least four are distinct. In this paper, we study the dynamics of Newton's functions of such polynomials. We also give the upper and lower bounds of the Hausdorff dimension of exceptional sets of these Newton's functions.
Controllability Approach to H Infinity Control Problem of Linear Time-Varying Switched Systems
Piyapong Niamsup
Lecture Notes in Engineering and Computer Science , 2008,
Abstract:
Effects of Organic Peroxides on the Curing Behavior of EVA Encapsulant Resin  [PDF]
Kanthamas Thaworn, Piyapong Buahom, Surat Areerat
Open Journal of Polymer Chemistry (OJPChem) , 2012, DOI: 10.4236/ojpchem.2012.22010
Abstract: Compounds of poly(ethylene-co-vinyl acetate) (EVA with vinyl acetate content 33%) with three different organic per- oxides, namely, dialkyl peroxide, peroxyester peroxide, and peroxyketal peroxide, were prepared with a twin screws extruder and a two-roll mixing mill. The cure behavior of the EVA compounds was analyzed from rheographs, which were obtained by a moving die rheometer (MDR) at various curing temperatures between 150?C to 170?C. The effects of organic peroxides on cure behavior were examined. The dynamic curing obtained by the torque rheometer provided sufficient experimental data to show that dialkyl peroxide is not suitable because it has a high half-life temperature and its by-products can discolor the final product. Peroxyester peroxide is good for curing at temperatures in the range of 150?C to 160?C, which accomplished an ultimate cure within 5 to 8 minutes. Also, the peroxyketal peroxide has higher performance, which decreased the optimum cure time to 3 minutes. The thermal decomposition mechanism of organic peroxide was applied to explain how the cure behavior is affected by generated free radicals.
-factors and -factors for near quasinorm on certain sequence spaces
Piyapong Niamsup,Yongwimon Lenbury
International Journal of Mathematics and Mathematical Sciences , 2005, DOI: 10.1155/ijmms.2005.2441
Abstract: We study the multiplicativity factor and quadraticity factor for near quasinorm on certain sequence spaces of Maddox, namely, l(p) and l∞(p), where p=(pk) is a bounded sequence of positive real numbers.
Analytic solution of certain second-order functional differential equation
Theeradach Kaewong,Piyapong Niamsup
International Journal of Mathematics and Mathematical Sciences , 2006, DOI: 10.1155/ijmms/2006/53828
Abstract: We consider the existence of analytic solutions of a certain class of iterative second-order functional differential equation of the form x″(x[r](z))=c0z2
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