• Korean Journal of Animal Reproduction
• /
• v.23 no.1
• /
• pp.85-92
• /
• 1999

This study was designed to determine effect of cryoprotectant kinds and cell stages on OPP vitrification method in mouse embryos. The freezing speed, cryoprotectants and cell stage could affect of embryo viability following various vitrification methods. The vitrification solution used were consisting of 40% (v/v) ethylene glycol, 18% (w/v) Ficoll, 0.3 M sucrose solution in holding medium (D-PBS supplemented with 5% FCS: HM) (EFS) or 16.5% ethylene glycol , 16.5% dimethyl sulfoxide, 0.5 M sucrose in HM (EDS). The embryos were collected from oviduct at 18 h after hCG injection and then washed and cultured in mHTF medium until use. In experiment 1, the blastocysts were vitrified by OPP straw to determine the optimal vitrification solution of EFS or EDS. The post-thaw survival rates at re-expanded stage rates were significantly different between EFS and EDS (95.0 vs 100%), but at hatching stage was not different between EFS and EDS (90.0 vs 95.0%). respectively. In experiment 2, zygotes, 2-, 4-cell, morula and blastocysts were vitrified by OPP method to determine the acceptable of early stage embryos. The development rates to expanded blastocyst in zygote (70.0%) were significantly lower rather than those in 2-, 4- 8-cell, compacted morula or blastocyst (89.7, 90.0, 92.8, 97.6 or 97.5%), respectively. However, the cell number of post-thaw developed to expanded blastocyst in blastocyst and control blastocyst stage (39.6$\pm$2.81, 35.7$\pm$2.98) were significanty higher than those in zygote, 2-, 4-, 8-cell, compacted morula (29.8$\pm$3.21, 31.3$\pm$3.83, 29.3$\pm$3.58, 28.9$\pm$3.21 or 30.8$\pm$2.93). In experiment 3, the zygotes were exposed in VSl for 1, 2, and 3 min to the optimal exposed time. The cleavage rates (91.6, 88.5, 88.9%) and develop mental rates to blastocyst (83.3, 74.3 and 69.4%) depends on the exposed time in VSl were not significantly different among 1, 2, or 3 min, respectively. The cell number also were not significantly different among exposed time in VS1. respectively. These results indicate that OPP method could be useful for vitrification either EFS or EDS vitrification solution. The post-thaw survival rates at zygote were significantly lower than those at 2-, 4-, 8-cell, morula or blastocyst, respectively. The zygote stage were more sensitive rather than late stage embryos. The exposing time in VS1 for 1 min was better than that for 2 or 3 min, even it was not significantly different. The OPP vitrification method could be useful of mouse embryos either with EFS or EDS vitrification solution.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.33 no.6
• /
• pp.597-599
• /
• 2000

This study was performed to find out the cryoprotectants for cryopreservation of trochophores and early D-shaped larvae of surf clam, Spisula sachalinensis. Dimethyl sulfoxide (DMSO), ethylene glycol, 1,2-propanediol and methanol were used as cryoprotectant Each cryoprotectant was made to 1.0 M, 2.0 M, 3.0 M with dilution of 0.2 M fructose and 0.2 M sucrose. The trochophoers and early D-shaped larvae were immersed in each preparation for 10 minutes to reach equilibration and cryopreserved in liquid nitrogen. Survival rates of post-thawed trochophores and early D-shaped larvae in 2.0 M DMSO with 0.2 M sucrose were the highest as $91.4{\%}\;and\;78.9{\%}$, respectively.

• Bulletin of the Korean Chemical Society
• /
• v.32 no.10
• /
• pp.3730-3734
• /
• 2011

The degree of self-assembly and the size variation of nanotubular structures in anodic titanium oxide prepared by the anodization of titanium in ethylene glycol containing 0.25 wt % $NH_4F$ at 40 V were investigated as a function of anodization time. We found that the degree of self-assembly and the size of the nanotubes were strongly dependent on thickness deviation and thus indirectly on anodization time, as the thickness deviation was caused by the dissolution of the topmost tubular structures at local areas during long anodization. A large deviation in thickness led to a large deviation in the size and number of nanotubes per unit area. The dissolution primarily occurred at the bottoms of the nanotubes ($D_{bottom}$) in the initial stage of anodization (up to 6 h), which led to the growth of nanotubes. Dissolution at the tops ($D_{top}$) was accompanied by $D_{bottom}$ after the formed structures contacted the electrolyte after 12 h, generating the thickness deviation. After extremely long anodization (here, 70 h), $D_{top}$ was the dominant mode due to increase in pH, meaning that there was insufficient driving force to overcome the size distribution of nanotubes at the bottom. Thus, the nanotube array became disorder in this regime.

• Bulletin of the Korean Chemical Society
• /
• v.25 no.6
• /
• pp.779-785
• /
• 2004

Syn (or anti) cinnamaldehydeoxime (1a, b) undergoes Diels-Alder addition to tetrabromo-p-benzoquinone (2)in dry xylene in 1 : 1 and 2 : 1 molar ratios to give the mono- and diadducts 3 and 4a, b respectively. The reaction of 3 with thioamides in ethanol gave thiazoloquinoline diones 6a-d, whereas with acid amides in ethylene glycol, it gave oxazoloquinolinediones 12a-f.

• Journal of Embryo Transfer
• /
• v.13 no.3
• /
• pp.313-321
• /
• 1998

This study was conducted to investigate the effects of equilibration and dilution methods on the survival rate of vitrified IVM-IVF bovine blastocysts. Vitrification solution was composed with 20% glycerol, 20% ethylene glycol, 3/8 M sucrose and 3/8 M dextrose in D-PBS supplemented with 20% FBS (GESD). Embryos were equilibrated in 1 of 3 methods: 3-step (El), 2-step (E2), or 1-step (E3), and after loading into 0.25-ml straws, were plunged into liquid nitrogen. After warming in water bath at 2$0^{\circ}C$, cryoprotectants were diluted in 1 of 3 methods: 1) D1(VS+1/2 M sucrose, 1/2 M sucrose and l/4 M sucrose), 2) D2 (1/2 M sucrose and 1/4 M sucrose), or 3) D3(1/2 M sucrose only). All procedures except warming were conducted at room temperature. Survival and hatching rates of blastocysts and expanded blastocysts following equilibration methods were 50 and 83.6%, and 27.8 and 67.3%, respectively in El, which were significantly higher (P〈0.01) than those of E2 (16.7 and 23.2%, and 7.4 and 12.5%, respectively) and 23 (0 and 3.7%, and 0 and 0%, respectively). Survival and hatching rates of expanded blastocysts were significantly (P〈0.01) higher than those of blastocysts in El. Survival rates of blastocysts and expanded blastocysts following dilution methods were 52% and 80.6% in D2, which were significantly higher (P〈0.05) than those of D1 (29.6 and 48.3%) and D3 (47.2 and 63.8%). Hatching rates of blastocysts were similar in D1, D2 and D3, however in expanded blastocysts, that of D2(61.3%) was significantly higher (P〈0.01) than that of D1(34.5%). Survival rates of expanded blastocysts in D1 and D2, and hatching rates in D2 and D3 were significantly higher(P〈0.01) than those of blastocysts. These results indicate that the viability of vitrified blastocysts was improved by the several steps of equilibration, and by 2-steps dilution after warming, independently of their stage of development. The results also indicated that the expanded blastocysts are more profitable to vitrification than blastocysts.

• Applied Chemistry for Engineering
• /
• v.5 no.3
• /
• pp.524-536
• /
• 1994

Chitosan is known to be a good biocompatible natural polymer. Polyethyleneglycol monomethacrylates(PEGM) were grafted onto chitosan and their reaction conditions and properties of the graft polymers obtained were estimated. Using ceric ammonium nitrate(CAN) as the initiator, the optimum condition for graft polymerization was determined amount of the initiator and monomer concentrations and reaction time. Grafting yields such as total conversion, the percentage of grafting and the efficiency of grafting were calculated and examined the optimum reaction condition for high grafting yields. The percentage of grafting and total conversion were maximum at condition that the concentration of initiator was $4{\sim}5{\times}10^{-3}M$, the concentration of monomer was 0.5~0.6M, the reaction time was 2~3 hours and the reaction temperature was about $40^{\circ}C$. Thermal characteristics, solubility for chitosan solvents and inherent viscosity of synthesized graft copolymers were investigated. In high initiator concentration, characteristics of chitosan were greatly diminshed. In case of inherent viscosities, chitosan-g-PE-90 was 2.81 dl/g, chitosan-g-PE-200, 3.01dl/g and chitosan-g-PE-350, 4.93dl/g. And a tendency of viscosity increase depending on the length of ethylene oxide residue was confirmed. Degree of swelling, tensile strength, elongation of membrane prepared from graft copolymers were determined. Properties of graft copolymers were affected by percentage of grafting and length of ethylene oxides residue in polyethylene glycol monomethacrylates. Tensile strength, elongation and degree of swelling of graft copolymers were remarkably improved than chitosan. As percentage of grafting increased, the amount of drug permeation was also increased.

• Proceedings of the Polymer Society of Korea Conference
• /
• 2006.10a
• /
• pp.263-263
• /
• 2006

Poly (ethylene glycol)(PEG) - Poly (${\varepsilon}-caprolactone(CL)$) - Poly (D,L lactide(LA) (PCLA-PEG-PCLA) was synthesized by ring-opening polymerization to form temperature sensitive hydrogel triblock copolymer. The triblock copolymer was acrylated by acryloyl chloride. ${\beta}-amino$ ester was used as a pH sensitive moiety, in this study ${\beta}$- amino ester obtained from 1,4-butandiol diacrylate, and 4, 4' trimethylene dipiperidine, it have pKb around 6.6. pH/temperature sensitive penta-block copolymer (PAE-PCL-PEG-PCL-PAE) was synthesized by addition polymerization from acrylated triblock copolymer, 1,4-butandiol diacrylate, and 4, 4' trimethylene dipiperidine. Their physicochemical properties of triblock and penta-block copolymers were characterized by $^1H-NMR$ spectroscopy and gel permeation spectroscopy. Sol-gel phase transition behavior of PAE-PCL-PEG-PCL-PAE block copolymers were investigated by remains stable method. Aqueous media of the penta-block copolymer (at 20 wt%) changed from a sol phase at pH 6.4 and $10^{\circ}C$ to a gel phase at pH 7.4 and $37^{\circ}C$. The sol-gel transition properties of these block copolymers are influenced by the hydrophobic/hydrophilic balance of the copolymers, block length, hydrophobicity, stereo-regularity of the hydrophobic of the block copolymer, and the ionization of the pH function groups in the copolymer depended on the changing of environmental pH, respectively. The degradation and the stabilization at pH 7.4 and $37^{\circ}C$, and the stabilization at pH 6.4 and $10^{\circ}C,\;5^{\circ}C,\;0^{\circ}C$, of the gel were determined. The results of toxicity experiment show that the penta block copolymer can be used for injection drug delivery system. The sol?gel transition of this block copolymer also study by in vitro test ($200{\mu}l$ aqueous solution at 20wt% polymer was injected to mouse). Insulin loading and releasing by in vitro test was investigated, the results showed that insulin can loading easily into polymer matrix and release time is around 14-16days. The PAE-PCL-PEG-PCL-PAE can be used as biomaterial for drug, protein, gene loading and delivery.

• Korean Journal of Soil Science and Fertilizer
• /
• v.10 no.1
• /
• pp.69-74
• /
• 1977

This study has been conducted to identify physico-chemical and clay mineralogical characteristics of bentonites produced in Korea for the purpose of finding good quality bentonite for agricultural ure. The results are summarized as follows: 1. Bentonites are mainly composed of montmorillonite developed from tuffs in a lava flow. 2. Chemical properties of bentonites are: pH in $H_2O$(1:1), 7:cation exchange capacity, 60-96me/100g; content of $SiO_2$, 54-72%; ratio of $SiO_2$ to $Al_2O_3$, 4.1-10.0;oven dry loss of $H_2O$ is higher than the ingnition loss of $H_2O$. 3. The x-ray diffrection patterns of powder bentonites show peaks at $14-15{\AA}$, $4.4{\AA}$, and $2.5{\AA}$, and that of swellen one show $17{\AA}$ when treated with ethylene glycol. 4. Distribution areas of the good quality bentonites were (1) Dogu-Dong, Donghae-Myeon, Yeonil-Gun, Gyeongsangbug-Do (2) Hamyeon-Ri, Yangnam-Myeon, Weolseong-Gun, Gyeongsanbug-Do. (3) Joam-Ri, Gangdong-Myeon, Weolseong-Gun, Gyeongsangbug-Do. (4) Sanha-Ri, Gangdong-Myeon, Ulju-Gun, Gyeongsangnam-Do. (5) Sinhyeon-Ri, Gangdong-Myeon, Ulju-Gun, Gyeongsangnam-Do. (6) Yonghang-Ri, Pyeongchang-Myeon, Pyeongchang-Gun, Gangweon-Do.

• Membrane Journal
• /
• v.23 no.2
• /
• pp.112-118
• /
• 2013

Polyancrylonitrile nanofiber membrane (PAM) was prepared by using the electrospinning method with a solution of polyacrylonitrile (PAN) in DMF. The pore-diameter of PAMs and the number of PAM's layer were controlled for the microfiltration (MF) application. In addition, in order to improve the water-flux, AN-PEGMA copolymers have been synthesized via free radical polymerization with poly (ethylene glycol) methyl ether methacrylate and azobisisobutylronitrile (AIBN), and then PAN/AN-PEGMA nanofiber membranes (PAM/APM) were prepared by electrospinning with a mixture of PAN (9 wt%) and AN-PEGMA (3 wt%) in DMF (88 wt%). The prepared membranes were investigated with FT-IR and E.D.S. It was confirmed through scanning electron microscope (SEM), porometer, and porosity analysis that the porous membrane with a uniform diameter (400~600 nm) and a uniform pore characteristics (0.5~0.4 ${\mu}m$) was prepared. For the MF application, water-flux measurements were investigated and then the result was shown that the water permeability value of PAM/APMs introduced AN-PEGMA copolymers was relatively higher than that of the PVdF commercial membrane. From these results, PAN nanofiber membranes prepared by electrospinning could be utilized as a MF membrane.

• Macromolecular Research
• /
• v.13 no.6
• /
• pp.467-476
• /
• 2005

The main objective of this study was to develop and characterize pH-sensitive biodegradable polymeric materials. For pH-sensitivity, we employed three kinds of moieties: 2-amino-3-(lH-imidazol-4-yl)-propionic acid (H), N-[4-( 4,6-dimethyl-pyrimidin-2ylsulfamoyl)-phenyl]succinamic acid (SM), and 2- {3-[ 4-( 4,6-dimethyl-pyrim­idin- 2-ylsulfamoyl)-phenylcarbamoyl]-propionylamino} -3-(3 H - imidazol-4-yl)-propionic acid (SH). The pH -sensitive diblock copolymers were synthesized by ring opening polymerization and coupling reaction from poly(ethylene glycol) (MPEG), $\varepsilon$-caprolactone (CL), D,L-lactide (LA) and pH-sensitive moieties. The pH-sensitive SH molecule was synthesized in a two-step reaction. The first step involved the synthesis of SHM, a methyl ester derivative of SH, by coupling reaction of SM and L-histidine methyl ester dihydrochloride, whereas the second step involved the hydrolysis of the same. The synthesized SM, SHM and SH molecules were characterized by FTIR, $^{1}H$-NMR and $^{13}C$-NMR spectroscopy, whereas diblock copolymers and pH-sensitive diblock copolymer were characterized by $^{1}H$-NMR and GPC analysis. The critical micelle concentrations were determined at various pH conditions by fluorescence technique using pyrene as a probe. The micellization and demicellization studies of pH-sensitive diblock copolymers were also done at different pH conditions. The pH-sensitivity was further established by acid-based titration and DLS analysis.