• The Korean Journal of Malacology
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• v.26 no.4
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• pp.297-302
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• 2010

Water temperature, salinity and density on egg development of the sunray surf clam, Mactra chinensis were investigated for artificial seedling production. The required time from fertilization to D-shaped larvae were 33.8 hours in $18^{\circ}C$, 20.6 hours in $23^{\circ}C$, 18.2 hours in $28^{\circ}C$ and 15.0 hours in $33^{\circ}C$. The development duration was reduced with increasing temperature. The relationships between temperature and the required time from egg to each developmental stage were described as follows: 2-cell, 1/h = 0.1051WT - 1.4782; 8-cell, 1/h = 0.037WT - 0.3686; gastrula, 1/h = 0.008WT - 0.0521; trochophore, 1/h = 0.0041WT - 0.0235; D-shaped larva, 1/h = 0.0024WT - 0.0102. Biological minimum temperature for the egg development was estimated to be $8.0^{\circ}C$ in average. The possible range of temperature for the development of D-shaped larvae was $18-28^{\circ}C$ and optimum of water temperature for the development of egg was $23^{\circ}C$. The possible range of salinity for the development of D-shaped larvae was 20-35 psu and optimum of salinity for the development of egg was 30-35 psu over 25 psu at least. The density of fertilized egg was below 40 per 1 ml in rearing seawater for elevating the development rate from fertilized egg to D-shaped larva.

• Journal of Aquaculture
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• v.15 no.1
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• pp.39-42
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• 2002

Water temperature, at which Spisula sachdinensis egg successfully completed development ranges from 10 to $25^{\circ}C$. Within this range, the development duration is reduced with increasing temperature. The relationships between temperature (WT, $^{\circ}C$) and the required time (t: hour) from egg to each developmental stage are described as follows: 2-cell : 1/t = 0.0554 WT -0.3769; 8-cell : 1/t = 0.0210 WT -0.1142; Morula : 1/t = 0.0125WT -0.0712; Trochophore : 1/t = 0.0039 WT -0.0203; D-shaped larva : 1/t = 0.0024W T -0.0108. Biological minimum temperature for the egg development is 5.5$^{\circ}C$.

• Journal of Aquaculture
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• v.16 no.2
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• pp.94-98
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• 2003

Effect of temperature (5, 10, 15, 18, 21$^{\circ}C$) on pre-and post-embryonic development of the sea urchin Strongylocentrotus intermedius was studied. The egg, which measured 122.5 ${\mu}{\textrm}{m}$, became globular. At 18$^{\circ}C$, it attained 4 celled stage at 3 hours after fertilization, hatched after 15 hours, 4-armed larval stage after 3 days and 8- armed larval stage after 20 days. The relationships between temperature (WT) and time (1, hour) required for each of the selected developmental stages are: Hatching: 1/t=0.0036WT+0.0088 Pyramid: 1/t=0.0014Wl-0.0016 4- armed: 1/t=0.0009WT-0.0020 6- armed: 1/t=0.0004WT-0.0005 8-armed : 1/t=0.0002WT+0.0002 Biological minimum temperature for the egg and larval development is calculated as 1.61$^{\circ}C$.

• Journal of Aquaculture
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• v.10 no.1
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• pp.17-24
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• 1997

In order to understand the spawning and larval development of Perinereis aibuhitensis for the effective seedling production, the influence of water temperature on spawning induction, egg and larval development of the worm were investigated from October 30, 1989 to October 30, 1990. Main spawning period was from July through September, and average diameter of mature eggs was $220\mu m$. The relationship between the adult weight (Wt) and the number of spawned eggs (NS) was given as follws : NS=48635.589Wt1.3044 (r=0.8572). Adult males and females died immediately after spawning. Trochophore larvae developed 12 hours after fertilization, and hatched out after 56 hours.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.6
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• pp.559-564
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• 2000

We studied to find out the effect of water temperature on the egg development of pearl oyster, Pincata fucata martensii and Pacific oyster, Crassostrea gigas. The optimum water temperatures for egg development were $20{\~}25^{\circ}C$ in P. fucata martensii and $15{\~}25^{\circ}C$ in C. gigas. The required time from fertilization to D-shaped lana was $41.7\;hours\;at\;20^{\circ}C$ and 27.5 hours at $25^{\circ}C$ in P. fucata martensii, and 35.3 hours at $15^{\circ}C$, 26.3 hours at $20^{\circ}C$ and 17.6 hours at$ 25^{\circ}C$ in C. gigas, respectively. The relationships between the water temperature ($WT:^{\circ}C$) and the required time (h: hour) from fertilization to each developmental stage were given as follows; P. fucata martensii Up to 8-cell $$1/h=0.0463WT-0.6945 (r^2=0.9702)$$ Up to morula $$1/h=0.0196WT-0.2184 (r^2=0.8118)$$ Up to trochophore $$1/h=0.0076WT-0.0802 (r^2=0.8756)$$ Up to D-shaped larva $$1/h=0.0031WT-0.0380 (r^2=0.9075)$$ C. gigas Up to 8-cell $$1/h=0.0210WT-0.1123 (r^2=0.9862)$$ Up to morula $$1/h=0.0143WT-0.1077 (r^2=0.9833)$$ Up to trochophore $$1/h=0.0052WT-0.0218 (r^2=0.9857)$$ Up to D-shaped lawn $$1/h=0.0029WT-0.0170 (r^2=0.9689)$$ Biological minimum temperature for egg development of P. fucata martensii and C. gigas was calculated as $$12.3^{\circ}C and 5.7{\circ}C$$, respectively.

• Food Science and Biotechnology
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• v.15 no.2
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• pp.189-195
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• 2006

A study was conducted to develop optimal conditions for a large-scale, sequential separation method for value-added components from egg yolk. Starting with liquid egg yolk, immunoglobulin Y (IgY), phospholipids, and neutral lipids were extracted sequentially using water, ethanol, and n-hexane. The remainder was yolk proteins. Adjusting the pH of diluted egg yolk to pH 5.0-5.2 decreased phospholipids content in the supernatant after centrifugation, which was very important for preventing clogging problem of ultrafiltration filters during the subsequent concentration step for IgY separation. Extraction of precipitants after centrifugation with four volumes of 100% ethanol once removed most of the phospholipids and the purity of phospholipids was more than 85% (wt.) after drying. The subsequent extraction of precipitant from ethanol extraction with four volumes of hexane 3 times removed neutral lipids almost completely and resulted in a high protein product with minimal lipids. The sequential separation method is considered to be advantageous for large-scale separations of many valuable components from egg yolk.

• Korean Journal of Poultry Science
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• v.41 no.1
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• pp.69-75
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• 2014

This study was carried out to investigate the performance of laying period of A and B strains of Korean native ducks (KND). One hundred sixty eight ducks were used in this work and divided into A and B strains (6 replications/strain, 14 birds/replication). Ducks were fed with laying ducks' feedstuff (CP 15%, ME 2,900 kcal/kg) for the age of 20~80 wk old. There was no significant difference on body weight, feed intake and egg weight between A and B strains. Weekly body wt of KNDs was the lowest at the age of 40~48 wk old, and that of those was high at the age of 24~32 wk and 64~80 wk old (P<0.05). Weekly feed intake significantly decreased at the age of 36~48 wk and 68~72 wk old (P<0.05), but there was no significant difference at the age of 52~56 wk old. Weekly egg wt was the lowest at the age of 32~40 wk old. Egg production ratio of B strain was higher compared to that of A strain at the age of 24~28 wk, 60~64 wk and 20~80 wk old. Weekly egg production ratio was the highest at the age of 28~32 wk old, and was high maintained until the age of 48 wk old. However, weekly egg production ratio decreased from the age of 52 wk old to the age of 68 wk old. Number of egg of B strain (267.5) was higher than that of A strain (235.6) at the age of 20~80 wk old. There was no significant difference on feed conversion ratio between A and B strain at the age of 28~36 wk old, but feed conversion ratio of A strain was higher than that of B strain at the other weeks (P<0.05). These results provided the basic data on the record of laying period of Korean native ducks.

• International Journal of Industrial Entomology and Biomaterials
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• v.14 no.1
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• pp.45-50
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• 2007

Ethanol extract of 20 botanicals in 3 concentrations i.e., 2.5%, 5% and 10% were evaluated for their efficacy to improve reproductive performance of mulberry silkworm (Bombyx mod L.) through feeding botanical enriched mulberry leaves during $2^{nd}$ day of $4^{th}$ age as well as $1^{st}$ and $3^{rd}$ day of $5^{th}$ age larvae. The preliminary screening was done by ranking the botanicals based on influence in most important reproductive contributing parameters such as single cocoon weight, effective rate of rearing, pupation rate, fecundity and recovery of eggs/kg cocoon. Five botanicals viz., Asparagus recemosus, Achyranthes aspera, Tribulus terrestris, Withania somnifera, Parthenium histerophorus ranked first were further evaluated at 8% 5% and 3% concentrations to confirm their effectiveness and standardize effective concentration. Among the rearing parameters, mature larval weight, shell ratio and number of cocoons/kg were not significantly influenced by the treatments. However, reproductive parameters such as effective rate of rearing (wt), pupation rate (%), fecundity (No.) and egg recovery (g)/kg cocoon were significantly (P<0.05) influenced by the botanicals. Higher fecundity and egg recovery were obtained on treatment with Withania somnifera irrespective of concentrations. However at 5% concentration, pupation rate, fecundity as well as egg recovery were found significantly higher than that of other concentrations, confirming its effectiveness for improving reproductive efficiency.

• Advances in nano research
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• v.16 no.2
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• pp.127-140
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• 2024

Upon direct/indirect exposure to flame or heat, composite structures may burn or thermally buckle. This issue becomes more important in the natural fiber-based composite structures with higher flammability and lower mechanical properties. The main goal of the present study was to obtain an optimal eco-friendly composite system with low flammability and high thermal buckling resistance. The studied composite consisted of polypropylene (PP) and short abaca fiber (AF) with eggshell powder (ESP) and halloysite clay nanotubes (HNTs) additives. An optimal base composite, consisting of 30 wt.% AF and 70 wt.% PP, abbreviated as OAP, was initially introduced based on burning rate (BR) and the Young's modulus determined by horizontal burning test (HBT) and tensile test, respectively. The effects of adding ESP to the base composite were then investigated with the same experimental tests. The results indicated that though the BR significantly decreased with the increase of ESP content up to 6 wt.%, it had a very destructive influence on the stiffness of the composite. To compensate for the damaging effect of ESP, small amount of HNT was used. The performance of OAP composite with 6 wt.% ESP and 3 wt.% HNT (OAPEH) was explored by conducting HBT, cone calorimeter test (CCT) and tensile test. The experimental results indicated a 9~23 % reduction in almost all flammability parameters such as heat release rate (HRR), total heat released (THR), maximum average rate of heat emission (MARHE), total smoke released (TSR), total smoke production (TSP), and mass loss (ML) during combustion. Furthermore, the combination of 6 wt.% ESP and 3 wt.% HNT reduced the stiffness of OAP to an insignificant amount by maximum 3%. Moreover, the char residue analysis revealed the distinct differences in the formation of char between AF/PP and AF/PP/ESP/HNT composites. Afterward, dilatometry test was carried out to examine the coefficient of thermal expansion (CTE) of OAP and OAPEH samples. The obtained results showed that the CTE of OAPEH composite was about 18% less than that of OAP. Finally, a theoretical model was used based on first-order shear deformation theory (FSDT) to predict the critical bucking temperatures of the OAP and OAPEH composite plates. It was shown that in the absence of mechanical load, the critical buckling temperatures of OAPEH composite plates were higher than those of OAP composites, such that the difference between the buckling temperatures increased with the increase of thickness. On the contrary, the positive effect of CTE reduction on the buckling temperature decreased by raising the axial compressive mechanical load on the composite plates which can be assigned to the reduction of stiffness after the incorporation of ESP. The results of present study generally stated that a suitable combination of AF, PP, ESP, and HNT can result in a relatively optimal and environmentally friendly composite with proper flame and thermal buckling resistance with no significant decline in the stiffness.

• Korean Journal of Poultry Science
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• v.20 no.3
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• pp.125-131
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• 1993

This study was performed to find the desirable conditions for processing salted hard-boiled egg without cracking egg shell in NaCl solution under pressure. Among the many factors affecting saltiness of the shell egg, concentration of NaCl solution(0~40%), different salting time(0~45h) and salting pressure (0~4.5kg/$\textrm{cm}^2$) were employed to identify the permeability of NaCl into shell egg at ambient temperature. The saltiness of the shell egg was proportionally risen as concentration of NaCl solution, salting time and pressure increased. The most desirable saltiness was observed at the 0.70~1.00% of NaCl in albumen and 0.40~0.45% in yolk, Besides the saltiness, sensory evaluation of the shell egg were carried out to evaluate the quality of the salted shell egg. The effect of various concentration of NaCl solution, salting time and pressure on sensory scores of hard-boiled salted eggs showed that 20~40% of NaCl solution, 12~20 h of salting time, 3~4.5 kg/$\textrm{cm}^2$ of salting pressure were proper conditions for processing the product. These results indicate that the desirable condition to get salted hard-boiled shell egg were ; 30% of NaCl solution, 16h of salting time and 4.0kg/$\textrm{cm}^2$ of salting pressure.