• Korean Journal of Animal Reproduction
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• v.17 no.3
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• pp.173-181
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• 1993

In order to demonstrate whether ovoperoxidase hardens the zona of oocytes activated by incubating in M-S buffer supplemented with 20$\mu$M of Ca-ionophore A 23187, the effect of peroxidase inhibitors(250mM pheylhydrazine, 28mM sodilum sulfite, 350mM glycine ethyl ester and 50mM sodium azide), tyrosine analogue(12.5mM tyramine) and exogeneous peroxidase(50$\mu\textrm{g}$/ml horseradishperoxidase ; HRP) on zona hardening in ionorphore-treated oocytes were investigated. The results obtained from thses experiments were summarized as follows : 1. The zona solubility (t50) of ionophore-activated and DMSO-treated oocytes at 1, 2 and 3 hr of culture were 25.0, 31.6 and 40.6min., and 9.7, 10.8 and 15.5 min., respectively. The longest time required for zona lysis of ionophore activated oocytes at 1 hr after onset of ionophore treatment. The diferences int50 for zona was significantly greater as compared to DMSO-treated controls(P<0.01). 2. The inhibition rates of hardening in the oocytes treated with the phenylhydrazine, sodium sulfite, glycine ethyl ester and sodium azide, were 23.8, 61.9, 95.2 and 23.8%l, respectively, and the tyramine, was 14.3%. Several known peroxidase inhibitors and tyrosine analogue were blocked zona hardening in ionophore activated oocytes. 3. The treatment of exogeneous peroxidase promoted the zona hardening of activated oocytes but not unactivated oocytes. These resuls indicate that the ovoperoxidase apparently catalyzes the hardening of the zona following ionophore activation of mouse oocytes.

• YAKHAK HOEJI
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• v.55 no.1
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• pp.1-10
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• 2011

Mastic is a bleed resin formed in pistacia lentiscus tree extract form the anacatdiaceae family. Mastic is used as a food ingredient in the Mediteraanean resin, and has been used by local inhabitants as a traditional medicine for relief of upper abdominal discomfort, dyspepsiaand peptic ulcer. Clinically, mastic has been effective in the treatment of benign gastric and duodenal, ulcers, giving symptomatic relief and endoscopically proven healing. In this study, to enhance activiteies of poorly water soluble Mastic with oils, surfactants and cosurfactants and then the mixure was microemulsified in aqueous media under condition of gentle agitation and digestive motility that would be encountered in the gastrointestinal tract. Formulation development and screening were based on phase diagrams and characteristics of resultant microemulsion. For optimum mastic formulation, microemulsions with various ratio (w/w%) of mastics, oils, surfactants and cosurfactants were prepared and their solubility was evaluated by monitoring particles size in their buffer through visual asessment and electrophoretic light scattering spectrophotomerter (ELS). In vitro activity of self microemulsified mastic (SME mastic) was determined by minimum ingibition concentration (MIC) test against a panel of Helicobacter pylori (H. pylori) clinical strains. Additionally, in vivo activity of SME masitc was investigated us mouse infected by CH275 of H. pylori. The mean diameter of SME mastic was less then 100 nm in water and SME mastic was showed similar antiboisis effect compared to tometronidazole, clarithromycin and omeproazole. Consequently, SME mastic would be effective system to exterminate H. pylori. If mastic were dose with combined treatment, mastic might augur well for effect of H. pylori eradication as good remedy.

• Korean Journal of Materials Research
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• v.14 no.4
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• pp.235-238
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• 2004

The LT-MBE (low temperature molecular beam epitaxy) allows to dope GaAs with Mn over its solubility limit. A 75 urn thick GaMnAs layers are grown on a low temperature grown LT-GaAs buffer layer at a substrate temperature of $260^{\circ}C$ by varying Mn contents ranged from 0.03 to 0.05. The typical growth rate for GaMnAs layer is fixed at 0.97 $\mu\textrm{m}$/h and the V/III ratio is varied from 25 to 34. The electrical and magnetic properties are investigated by Hall effect and superconducting quantum interference device(SQUID) measurements, respectively. Double crystal X-ray diffraction(DCXRD) is also performed to investigate the crystallinity of GaMnAs layers. The $T_{c}$ of the $Ga_{l-x}$ /$Mn_{x}$ As films grown by LT-MBE are enhanced from 38 K to 65 K as x increases from 0.03 into 0.05 whereas the $T_{c}$ becomes lower to 45 K when the V/III ratio increases up to 34 at the same composition of x=0.05. This means that the ferromagnetic exchange coupling between Mn-ion and a hole is affected by the growth condition of the enhanced V/III ratio in which the excess-As and As-antisite defects may be easily incorporated into GaMnAs layer.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.51 no.4
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• pp.351-361
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• 2018

This study investigated the potential of collagenous protein fractions (CPFs) as functional foods. The specific CPFs studied were recovered from the roe of bastard halibut (BH), Paralichthys olivaceus; skipjack tuna (ST), Katsuwonus pelamis; and yellowfin tuna (YT), Thunnus albacares through the alkaline solubilization process at pH 11 and 12. The buffer capacity, water-holding capacity and solubility of CPFs with pH-shift treatment were significantly better at alkaline pH (10-12) than at acidic pH (2.0). At pH-shift treatment (pH 2 and 12), the foaming capacities of CPFs from ST and YT were improved compared to those of controls, but they were unstable compared to BH CPFs. The emulsifying activity index (EAI, $m^2/g$ protein) of CPFs (controls) was 16.0-21.1 for BH, 20.1-23.9 for ST and 9.3-13.7 for YT (P<0.05). CPFs adjusted to pH 12 showed improved EAI and YT CPFs showed significantly greater emulsifying ability than those from BH and ST. CPFs recovered from fish roe are not only protein sources but also have a wide range of food functionalities, confirming the high availability of fish sausage and surimi-based products as protein or reinforcing materials for functional foods and alternative raw materials.

• Proceedings of the SCSK Conference
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• 2003.09a
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• pp.501-519
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• 2003

Silk Sericin(SS) is a natural protein extracted from cocoon of bombix mori and shows moisturizing effect to the skin due to a number of hydroxyl groups in the structure. But its application to cosmetics is limited due to its poor solubility in water. In order to solve this drawback and expand its application to cosmetics, polyethyleneglycol(PEG) was conjugated with sericin by reacting activated polyethyleneglycol(ActPEG). Reaction site of sericin is tyrosine residue, which was determined by using $^1$H-NMR. Random coil structure of sericin was transformed to beta-sheet structure by conjugating polyethyleneglycol. It was confirmed that melting point of sericin-PEG conjugate was lowered compared to that of each sericin and PEG due to the interaction between sericin and PEG in crystalline structure. Self-assembled sericin-PEG nanoparticle was obtained by dialyzing with alcohol solution of sericin-PEG conjugate against water. The particle is spherical and has 200-400nm of size. The moisturizing ability of sericin-PEG nanoparticle was much higher than that of sericin itself. Incorporation of vitamin A into sericin-PEG nanoparticle was carried out by diafiltration method. The content of incorporated Vitamin A in sericin-PEG nanoparticle was 8.9 wt％. Releasing behaviour of vitamin A incorporated into nanoparticle was tested in phosphate buffer, pH 7.4 at 37$^{\circ}C$. and half-life of Vitamin A release was 43hrs. Sericin-PEG nanoparticle exhibited higher moisturing effect than sericin itself and distilled water, respectively. No toxicity and irritation were observed in animal tests. It can be expected that the self-assembled sericin-PEG nanoparticle can be developed for cosmetics.

• Economic and Environmental Geology
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• v.56 no.5
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• pp.603-618
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• 2023

This study focused on evaluating the suitability of the WRK (waste repository Korea) bentonite as a buffer material in the SNF (spent nuclear fuel) repository. The U (uranium) adsorption/desorption characteristics and the adsorption mechanisms of the WRK bentonite were presented through various analyses, adsorption/desorption experiments, and kinetic adsorption modeling at various pH conditions. Mineralogical and structural analyses supported that the major mineral of the WRK bentonite is the Ca-montmorillonite having the great possibility for the U adsorption. From results of the U adsorption/desorption experiments (intial U concentration: 1 mg/L) for the WRK bentonite, despite the low ratio of the WRK bentonite/U (2 g/L), high U adsorption efficiency (>74%) and low U desorption rate (<14%) were acquired at pH 5, 6, 10, and 11 in solution, supporting that the WRK bentonite can be used as the buffer material preventing the U migration in the SNF repository. Relatively low U adsorption efficiency (<45%) for the WRK bentonite was acquired at pH 3 and 7 because the U exists as various species in solution depending on pH and thus its U adsorption mechanisms are different due to the U speciation. Based on experimental results and previous studies, the main U adsorption mechanisms of the WRK bentonite were understood in viewpoint of the chemical adsorption. At the acid conditions (＜pH 3), the U is apt to adsorb as forms of UO₂²⁺, mainly due to the ionic bond with Si-O or Al-O(OH) present on the WRK bentonite rather than the ion exchange with Ca²⁺ among layers of the WRK bentonite, showing the relatively low U adsorption efficiency. At the alkaline conditions (>pH 7), the U could be adsorbed in the form of anionic U-hydroxy complexes (UO₂(OH)₃^-, UO₂(OH)₄^2-, (UO₂)₃(OH)₇^-, etc.), mainly by bonding with oxygen (O^-) from Si-O or Al-O(OH) on the WRK bentonite or by co-precipitation in the form of hydroxide, showing the high U adsorption. At pH 7, the relatively low U adsorption efficiency (42%) was acquired in this study and it was due to the existence of the U-carbonates in solution, having relatively high solubility than other U species. The U adsorption efficiency of the WRK bentonite can be increased by maintaining a neutral or highly alkaline condition because of the formation of U-hydroxyl complexes rather than the uranyl ion (UO₂²⁺) in solution,and by restraining the formation of U-carbonate complexes in solution.

• Economic and Environmental Geology
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• v.51 no.2
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• pp.77-85
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• 2018

There would be a possibility of uranium contamination around the nuclear power plants and the underground waste disposal sites, where the uranium could further migrate and diffuse to some distant places by groundwater. It is necessary to understand the biogeochemical behaviors of uranium in underground environments to effectively control the migration and diffusion of uranium. In general, various kinds of microbes are living in soils and geological media where the activity of microbes may be closely connected with the redox reaction of nuclides resulting in the changes of their solubility. We investigated the adsorption and precipitation behaviors of dissolved uranium on some solid materials using hydrogen gas as an electron donor instead of organic matters. Although the effect of hydrogen gas did not appear in a batch experiment that used granite as a solid material, there occurred a reduction of uranium concentration by 5~8% due to hydrogen in an experiment using bentonite. This result indicates that some indigenous bacteria in the bentonite that have utilized hydrogen as the electron donor affected the behavior (reduction) of uranium. In addition, the bentonite bacteria have showed their strong tolerance against a given high temperature and radioactivity of a specific waste environment, suggesting that the nuclear-biogeochemical reaction may be one of main mechanisms if the natural bentonite is used as a buffer material for the disposal site in the future.

• Journal of Pharmaceutical Investigation
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• v.32 no.3
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• pp.185-190
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• 2002

To improve the solubility of poorly water-soluble drug and to develop a sustained release tablets, the need for the technique, the formation of solid dispersion with polymeric materials that can potentially enhance the dissolution rate and extent of drug absorption was considered in this study. The 1:1, 1:4, and 1:5 solid dispersions were prepared by spray drying method using PVP K30, ethanol and methylene chloride. The dissolution test was carried out at in phosphate buffer solution at $37^{\circ}C$ in 100 rpm. Solid dispersed drugs were examined using differential scanning calorimetry and scanning electron microscopy, wherein it was found that felodipine is amorphous in the PVP K30 solid dispersion. Felodifine SR tablets were prepared by direct compressing the powder mixture composed of solid dispersed felodipine, lactose, Eudragit and magnesium stearate using a single punch press. In order to develop a sustained-release preparation containing solid dispersed felodipine, a comparative dissolution study was done using commercially existing product as control. The dissolution rate of intact felodipine, solid dispersed felodipine and its physical mixture, respectively, were compared by the dissolution rates for 30 minutes. The dissolution rates of felodipine for 30 minutes from 1:1, 1:4, 1:5 PVP K30 solid dispersion were 70%, 78% and 90%. However, dissolution rate offelodipine from the physical mixture was 5% of drug for 30 minutes. Our developed product Felodipine SR Tablet showed dissolution of 17%, 50% and 89% for 1, 4, and 7 hours. This designed oral delivery system is easy to manufacture, and drug releases behavior is highly reproducible and offers advantages over the existing commercial product. The dissolution rate of felodipine was significantly enhanced, following the formation of solid dispersion. The solid dispersion technique with water-soluble polymer could be used to develop a solid dispersed felodipine SR tablet.

• KSBB Journal
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• v.22 no.5
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• pp.345-350
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• 2007

Phosphosugars are found in all living organisms and are commercially valuable compounds with possible applications in the development of a wide range of specialty chemicals and medicines. In carbohydrate metabolism, fructose 6-phosphate (F6P) is an essential intermediate formed by phosphorylation of 6' position of fructose in glycolysis, gluconeogenesis, pentose phosphate pathway and Calvin cycle. In glycolysis, F6P lies within the glycolysis metabolic pathway and is produced by isomerisation of glucose 6-phosphate. For large-scale production, F6P could be produced from starch using many enzymes such as pullulanase, starch phosphorylase, isomerase and mutase. In enzymatic reactions carried out at high temperatures, the solubility of starch is increased and microbial contamination is minimized. Thus, thermophile-derived enzymes are preferred over mesophile-derived enzymes for industrial applications using starch. Recently, we reported the production of glucose 1-phosphate (G1P) from starch by Thermus caldophilus GK24 enzymes. Here we report the production of F6P from starch through three steps; from starch to glucose 1-phosphate (glucan phosphorylase, GP), then glucose 6-phosphate (phosphoglucomutase, GM) and then F6P (phosphoglucoisomerase, GI). Using 200 L of 1.2% soluble starch solution in potassium phosphate buffer, 1,253 g of G1P were produced. Then, 30% yields of F6P were attained at the optimum reaction conditions of GM : G1 (1 : 2.3), 63.5$^{\circ}C$, and pH 6.85. The optimum conditions were found by response surface methodology and the theoretical values were confirmed by the experiments. The optimum starch concentrations were 20 g/L under the given conditions.

• Journal of the Korean Electrochemical Society
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• v.4 no.3
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• pp.87-93
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• 2001

Pressure-balanced external Ag/AgCl electrode has been extensively used for both Pressurized Water Reactor (PWR) and Boiling Water Reactor (PWR) environments. The use of KCI-based buffer solution often becomes the source of electrode potential drift due to slow leakage through its porous plug, typically made of zirconia. It is reported that results of our effort to improve the stability of electrode potential by using high purity water as the filling solution in which $Cl^-$ ion activity can be established and maintained at the solubility of AgCl even with the sustained leakage for a long period. Stability tests have been made in boron and lithium mixture solution at $288^{\circ}C$. The electrode potential remained stable within 10 mV over one week period. And after a thermal cycle between 288 to $240^{\circ}C$ the potential shift of Ag/AgCl electrodes did not exceed 15 mV By using the limiting equivalent ionic conductances and Agar's hydrodynamic theory, the thermal liquid junction potential (TLJP) of the electrode has been predicted. The calculated values for the water-fiued Ag/AgCl electrode potential, in which the chlorine concentration in the filling solution was derived from the measured data at ambient temperature, had a good agreement with the experimental values.