• KOREAN JOURNAL OF CROP SCIENCE
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• v.57 no.3
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• pp.226-232
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• 2012

Through the sampling four rice cultivars with differing amylose contents, the relationship between the structural and gelatinization properties of endosperm starches was analyzed. These rice varieties exhibited different chain length distribution ratio within the amylopectin cluster as well as varing amylose levels. The proportion of amylopectin short chains of in Goami cutlivars was higher than the other varieties, whereas the Goami 2 which shows amylose extender mutant properties in the endosperm showed the highest proportion of long chains. In X-ray diffraction analysis of rice starches, the Goami 2 variety displayed a B-type pattern whereas the other varieties were all A-type. Among the cultivars with high and normal rice starch levels, those with the higher amylose contents showed distinctly lower swelling. Goami 2 rice was found to have the highest onset and peak gelatinization temperature from the differential scanning calorimetry results. The four rice cultivars under analysis also showed different rates of hydrolysis by amyloglucosidase. These findings suggest that the composition and chemical structure of the starch content is a major determinant of both the gelatinization and functional properties of rice.

• Journal of the Korean Wood Science and Technology
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• v.27 no.1
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• pp.72-78
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• 1999

To accelerate the curing and to improve the bonding properties of urea-melamine-formaldehyde (UMF) resin adhesives for plywood, the effects of resin compositions and additives on gelation time and bonding strength were discussed. The gelation time of UMF resin prepared by simultaneous reaction with urea(U), melamine(M) and formaldehyde(F) at M/U molar ratio 0.2 was shortened as the molar ratio of formaldehyde to urea was increased. However, at F/U molar ratios higher than 2.5, the amounts of free fomaldehyde of resin could not satisfy with KS standard, Therefore, it was difficult to increase the amount of formaldehyde in resin composition for the purpose of fast gelation time. With increasing the molar ratio of melamine to urea(M/U) from 0.3 to 0.6 at constant F/U molar ratio 3.4, the gelation time of UMF resin was slightly decreased, while gradually increased at M/U molar ratio higher than 0.6. The gelation properties of UMF resin and bonding strength of UMF-bonded plywood could be enhanced by using ammonium chloride and p-toluene sulfonic acid as a curing-agent together with wheat flour and corngluten powder as a extender.

• Journal of Embryo Transfer
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• v.28 no.1
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• pp.63-71
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• 2013

In this study, we used flow a cytometric assay to evaluate plasma membrane integrity and mitochondrial activity in post-thawed sperm that was supplemented with ginsenoside-$Rg_1$. Varying concentrations of ginsenoside-$Rg_1$ (0, 25, 50 and $100{\mu}M/ml$) were used in the extender during cryopreservation to protect the DNA of thawed sperm, thereby increasing the viability and motility rate as evaluated using a computer-assisted sperm analysis (CASA) method. The results derived from CASA were used to compare the fresh, control, and ginsenoside-$Rg_1$ groups. Sperm motility and the number of progressively motile sperm were significantly (p<0.05) higher in the $50{\mu}M/ml$ ginsenoside-Rg1 group ($61.0{\pm}4.65%$) than in the control ($46.6{\pm}7.02%$), $25{\mu}M/ml$ ($46.2{\pm}4.76%$), and $100{\mu}M/ml$ ginsenoside-$Rg_1$ ($52.0{\pm}1.90%$) groups. However, the velocity distribution of post-thawed sperm did not differ significantly. Membrane integrity and MMP staining as revealed using flow cytometry were significantly (p<0.05) higher ($91.6{\pm}0.82%$) in the $50{\mu}M/ml$ ginsenoside-$Rg_1$ group than in the other groups. Here, we report that ginsenoside-$Rg_1$ affects the motility and viability of boar spermatozoa. Moreover, ginsenoside-$Rg_1$ can be used as a protective additive for the suppression of intracellular mitochondrial oxidative stress caused by cryopreservation.

• Journal of Embryo Transfer
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• v.32 no.4
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• pp.337-342
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• 2017

The present study was aimed to determine the effects of green tea extract (GTE) and beta-mercaptoethanol (${\beta}-ME$) supplementation in boar sperm freezing extender on in vitro fertilization (IVF) and reactive oxygen species (ROS) and glutathione (GSH) levels of presumptive zygotes (PZs). Experimental groups were allocated into lactose egg yolk (LEY) without antioxidant (control), GTE (1,000 mg/l in LEY) and ${\beta}-ME$ ($50{\mu}M$ in LEY). In freezing, spermatozoa extended with LEY were cooled to $5^{\circ}C$ for 3 h and then kept at $5^{\circ}C$ for 30 min following dilution with LEY containing 9% glycerol and 1.5% Equex STM. The final sperm concentration was $1{\times}10^8/ml$. Spermatozoa were loaded into straws and frozen in nitrogen vapor for 20 min. For IVF, oocytes were matured in NCSU-23 medium and co-cultured with spermatozoa following thawing at $37^{\circ}C$ for 25 sec. At 12 h following IVF, IVF parameters (sperm penetration and monospermy) were evaluated. In addition, GSH and ROS levels of PZs were determined by Cell Tracker Blue CMF2HC and DCHFDA, respectively. IVF parameters did not show any significant difference among the experimental groups. GSH and ROS levels of PZs were not significantly different between groups. In conclusion, antioxidant supplementation in boar sperm freezing could not influence IVF parameters, ROS and GSH levels of PZs.

• Reproductive and Developmental Biology
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• v.28 no.4
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• pp.261-265
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• 2004

The present study was conducted to assess sperm characteristics in miniature-pig. The semen samples were transported to the laboratory at 17℃ within 3 hours after collection. The extended semen was stored at 17℃, and sperm quality was evaluated at 0, 1, 3, 5 and 7 days after storage. The semen volume of miniature-pig (62±22㎖) was significantly (p<0.05) lower than that of Duroc (155±25㎖) and Yorkshire (154±23㎖). Significant differences were also observed in sperm concentrations. During 3 days of storage, sperm viability did not differ among miniature-pig, Duroc and Yorkshire. However, the viability was significantly (p<0.05) lower in miniature-pig than in Duroc and Yorkshire semen after Day 3 of storage. In abnormality, acrosome intactness and intensity, there were no differences among miniature-pig, Duroc and Yorkshire semen. On the other hand, the viability of frozen-thawed sperm in miniature-pig was significantly (p<0.05) lower than in that of Duroc and Yorkshire. This study also examined CTC patterns in frozen-thawed spermatozoa. The rates of AR pattern were higher in miniature-pig than in Duroc and Yorkshire. However, no difference was found in F, B and AR patterns. The results of present study suggest that further research is necessary to develop of semen extender and freezing methods to improve sperm quality in miniature-pig.

• Journal of Embryo Transfer
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• v.21 no.1
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• pp.77-83
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• 2006

본 연구는 개 동결 정액 융해 시 straw 크기 및 융해 속도가 융해 정자의 질(quality)에 미치는 영향을 조사하고 최적의 융해 조건을 조사하는데 그 목적이 있다. 정상적인 번식능을 가진 비글 수컷 5마리에서 정액을 채취하여 원심 분리하여 정장을 버리고 남은 정자에 동결보호제인 glycerol이 첨가된 tris-glucose-egg yolk extender를 첨가하여 동결하고 액체질소에 보관한 후 융해하였다. 동결 융해 조건에 따른 효과를 알아보기 위해 straw는 0.25 ml과 0.5 ml크기를 사용하였고 융해 조건은 $75^{\circ}C$에 10초, $55^{\circ}C$에 12초 및 $37^{\circ}C$에서 120초로 하여 융해 후 정자의 활력도(vigor), 운동성(motility), Hypo-osmotic test(HOS test)를 이용한 생존성(viability) 및 $SperMac^{\circledR}$ 염색을 하여 정자의 membrane integrity를 비교 조사하였다. 조사 결과 0.5 ml 크기의 straw를 사용한 경우 $37^{\circ}C$ 융해가 $55^{\circ}C,\;75^{\circ}C$ 융해보다, 0.25 ml 크기의 straw를 사용한 경우에는 $37^{\circ}C,\;55^{\circ}C$ 융해가 $75^{\circ}C$ 융해보다 유의적으로 높은 활력 지수 및 생존성을 보였다(P<0.05). Straw크기에 따라 비교하였을 경우 0.5 ml 군에서 유의적으로 높은 활력도, 생존성 및 membrane integrity를 보였다(P<0.05). 결론적으로 개 정액이 동결 및 융해 시 0.5ml straw를 이용하여 동결한 후 $37^{\circ}C$에서 120초 동안 융해하는 것이 최적의 조건임이 사료된다.

• Polymer(Korea)
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• v.35 no.2
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• pp.171-175
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• 2011

Isophorone diisocyanate(IPDI), polytetramethylene glycol 1000 (PTMG1000), and N-methyl diethanol amine (MDEA) were applied to prepare cationic polyurethane water dispersions (PUD). Various neutralizers and chain extenders were introduced in order to investigate property changes, such as particle size, viscosity, $T_g$, tensile strength, and water swellability, depending on chemical structure of those chemicals. While the PUDs neutralized by acetic acid showed a typical elastomeric behavior, the others used with hydrochloride presented crystalline behavior. Among chain extenders isophorone diamine (IPDA) provided the best mechanical property. The particle size of the PUD neutralized with HCl was smaller than that with acetic acid. It is believed that this is attributed to the size difference of counter ions. The PUD chain-extended with hydrazine had the smallest particle size.

• Polymer(Korea)
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• v.37 no.2
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• pp.167-176
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• 2013

Linear and cross-linked waterborne polyurethanes (WPUs) based on isophorone diisocyanate and mixed diols of poly(tetramethylene glycol)/hydroxyethyl-terminated polydimethylsiloxane (PDMS-OH) were synthesized with dimethylol propionic acid as an anionic component, trimethylolpropane as a cross-linking agent, and butanediol as a chain extender and characterized. The hydrophobicity, $T_g$, stress-strain behaviors of the linear or cross-linked siloxane-containing WPU (WPU-Si) films with different PDMS content were analyzed by using water contact shape analyzer, energy dispersive spectrometer, dynamic mechanical analyzer, and universal testing machine. The results reveal that as the PDMS content increased, the hydrophobicity of WPU-Si films increased, $T_g$ moved to higher temperature, the breaking stress increased, and the breaking strain decreased.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.25 no.1
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• pp.37-54
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• 1999

Planarized SiO$_2$ particles were prepared by two-step reduction method of making much smaller particles, micron-sized ones, to improve spreadability, adherence, and smoothness. Various pigments known as flaky extender usually have terrace layers on their surfaces, but SiO$_2$ Particles in this study exhibit a smooth surface structure. These single SiO$_2$ particles were used for core particles to prepare the composite particles coated with ultra fine TiO$_2$ particles by a homogeneous precipitation method. The thickness and the morphology of the deposited TiO$_2$ layer could be altered by adjusting the reactant concentrations, reaction time and temperature. The characteristics of SiO$_2$/TiO$_2$composite in the field of color cosmetics is to give a UV-cut effect and to enhance the chroma of human skin color, one of optical properties.

• Clean Technology
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• v.23 no.2
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• pp.148-157
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• 2017

To prepare UV-curable polyurethane-acrylate oligomer, NCO-terminated urethane prepolymers with trimethylolpropane, [TMP; 0 (0), 0.1 (0.021) and 0.2 (0.043) mole (mole fraction)] as crosslinkable tri-functional chain extender were end-capped with pentaerythritol triacrylate [PETA; 2.0 (0.400), 1.7 (0.354) and 1.4 (0.304) mole (mole fraction)] with one hydroxyl group/three vinyl functionalities. The stable as-formulated UV-curable polyurethane-acrylates [stable mixtures of PETA-capped oligomer/reactive acrylic monomer diluents without/with heptadecafluorodecyl methacrylate (PFA; 0, 6 and 9 wt%)] were formed up to 0.2 (0.043) mole (mole fraction) of TMP content in the prepolymer, while homogeneous-mixing failed at 0.3 (0.068) mole (mole fraction), in which the crosslink density in NCO-terminated urethane prepolymer was too high to enable the formation of stable mixture. This study examined the effect of TMP/PETA molar ratio and heptadecafluorodecyl methacrylate (PFA) content (wt%) on the properties of UV-cured polyurethane-acrylates as marine antifouling coating materials. The properties of UV-cured polyurethane-acrylate were found to be significantly dependent on the crosslinkable TMP/PETA ratio and PFA content. With the increasing of the TMP and PFA contents, the contact angles increased, and consequently the surface tension decreased. The adhesion of algae/barnacles to PFA contained film samples were found to be sufficiently weak to allow their easy removal. These results suggest that the UV-cured samples containing PFA have strong potential as coating materials for antifouling applications.