• Journal of the Society of Cosmetic Scientists of Korea
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• v.30 no.3 s.47
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• pp.353-359
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• 2004

The extent of silica flocculation can be modified by varying the silica concentration, aqueous phase pH, salt and polvmer concentration. High volume fraction W/O emulsion stabilized by hydrophobic silica was established with various aqueous phase conditions for cosmetic application. By increasing the silica concentration up to $1.0\;wt\%,$ the size of droplet decreased. A high silica concentration increased the viscosity of continuous oil phase by network formation, which resulted in target size of droplet. The stability of W/O emulsion is improved as increasing the aqueous phase pH. At low and intermediate pH, the emulsions became more stable by adding salt $(0.083\;mol\;dm^{-3}\;MgSO_4).$ At high PH, the presence of salt caused significant destabilization. The gelation behavior of the emulsion indicates that the effect of salt on silica-stabilized emulsion is derived from an electrostatic attraction. The addition of xanthan gum in aqueous phase increased the mono-dispersity of the W/O emulsion by making water more hydrophobic and hindering the recombination of droplets. In conclusion, these results indicate that very stable emulsifier-free, finely dispersed W/O emulsion can be achieved for cosmetic application by changing the aqueous phase composition.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.18 no.1
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• pp.99-132
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• 1992

Polypeptide has been used broadly as an active ingredient in cosmetics We thought it is very important to investigate the adsorption behavior of polypeptide in order to pre-estimate the effect of these polypeptides. For the study of polypeptide adsorption, we have investigated complex formation of basic homopolypeptides, poly(L-proline) Form I [PLP(I)], Form II [PLP(II)] and poly(4-hydroxy-L-proline) (PHLP) with acidic homopolypeptides, poly(L-glutamic acid) (PLGA), poly(D-glutamic acid) (PDGA) and poly(L-aspartic acid) (PLAA) through hydrogen bonding in a hydroalcoholic medium with viscometer, 1ight scatter, pH meter and circular dicroism (CD). The polypeptides used in this study have helical structure in some conditions. The result exhibited that al 1 the complexes were formed as the composition of basic/acidic homopolypeptide : L:2 irrespective of the complex systems used. A more favorable complex is formed in the PLP(II)-PLGA system than PHLP-PLGA because PLP(II) has a more flexible helical conformation, whereas PHLP has a more rigid helical conformation. The right-handed helix PLGA formed the complex favorably and quickly with the left-handed helix PLP(II), whereas the left-handed helix PDGA formed the complex favorably with the right-handed helix PLP(I). The effect of side chain of the acidic homopolypeptides on the complexation was also studied. The result showed that more favorable condition for the complexation was PLGA-PLP(II) system which has longer side chain at acidic homopolypeptide than PLAA - PLP(II). All the above facts were well supported by CD measurement for the complex systems. By the CD spectra for the complexes we could deduce the conformational change of each homopolypeptide in the complexes On the basis of the above results, we performed the adsorption test of PLP(I, II) and PHLP on the hair having a left-handed helix. The adsorption amount of each polypeptide was analyzed by HPLC. The result showed that PLP(I) was adsorbed more than PLP(II), PLP(II) was adsorbed more than PHLP on the hair. On adsorbing polypeptides having a helical structure on the hair through hydrogen bonding, it could be concluded that the helical polypeptides having the opposite directional structure to the hair are adsorbed more than those having the same directional structure with the hair and also the polypeptides having a flexible conformation are adsorbed more than those having a rigid conformation.

• The Korean Journal of Zoology
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• v.39 no.1
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• pp.36-46
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• 1996

An endogenous phenoloxidase (EPO) from earthworm, Lumbricus rubellus, has been purified and characterized. The purified EPO using ammonium sulfate fractionation, Blue-2, Phenyl-, and Q-sepharose chromatography steps was revealed in SDS-PAGE as a single protein banri with Mr. of 59 kl)a. A native strudure of the enzyme was examined with an in situ staining of a nondenatudng-PAGE using DL-dopa as a substrate. The result showed that a single band due to the EPO activity was located siighdy above a standard polypeptide with Mr. of 210 kl)a. These fads indicate that the EPO is an oligomeric enzyme. The presence of a monophenolase activity of the purified EPO, which hydroxylates tyrosine to dopa, was confirmed by observing dopachrome accumulation at 475 nm at PH 8.0 with a typical lag phase during 60 mm. of meausrement. A series of inhibition study has been performed for the enzyme with several divalent cation chelators such as phenyithiourea (Flu), 1, lO-phenanthroline, EDTA, and EGTA. Among them, only V'flj inhibited the enzyme with 1C0.5 of 65 MM, which indicated that copper was critical for the catalysis of EPO. The enzyme was maximally active at 35'C and pH 8.0 when L-dopa to dopachrome conversion was spectrophotometricaily monitored at 475 nm. The apparent Km values of P0 for L-opa were obtained as 1.86 mM and 13.8 mM at pH 6.5 and 8.0, respectively. The catalytic efficiencies at both pH were almost identical [(kat/Km)pH8.0/(kcat/Km)pH6.5 = O.92] while the Vmax at p11 8.0 was 6.6-fold higher than that at pH 6.5. This fact may indicate that pH affeds the catalysis at substrate and/or enzyme-substrate complex level rather than the enzyme itself. Taken together, the EPO was an oligomeric enzyme which did not require proteolysis for its activation. These results also indicated that the enzyme can exist, at least, in part as a latent form In vivo, which might be distinct from the prophenoloxidase activating system. Therefore, it is pertinent to consider that there must be certain regulatory molecules or phenomena in L. rubellus which make the 1,0 in a latent form in vivo before the foreign invasions.

• Journal of the korean academy of Pediatric Dentistry
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• v.31 no.4
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• pp.555-563
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• 2004

The pH of beverages is known to be low and have, therefore, been implicated in the increasing incidence of erosion. Erosion is believed to be the predominant cause of teeth wear in children and young adults, although there will always be a contribution from attrition and abrasion. The aim of the present study was to evaluate the effect of yogurt on the progression of erosive demineralization in human enamel using demineralization model in vitro. In 4 yogurts, available on the market, pH, buffering capacity and the concentrations of calcium, phosphate and fluoride were determined. The buffering effect was determined by titration with NaOH. 50 milliliters of each drink was then titrated with 1M sodium hydroxide, added in 0.5 milliliters increments, until the pH reached about 7. Human deciduous enamel(n=40) samples were divided into four groups and exposed to 80ml of the yogurt for 30,60, 90 and 120min. Enamel surface microhardness(VHN) was examined before and after each exposure. 1. The average PH of fermented milk was 3.77 and this pH value was acidic enough to cause tooth erosion. 2. All of the fermented milks were found to be erosive(p<0.05) 3. The teeth exposed to the fermented milk all showed erosion like lesions and microhardness measurements showed that enamel surface hardness decreased proportionately with increased time of immersion in all tooth specimen groups. 4. After immersion for 30 and 60 minutes, reduction rate of microhardness values was not significantly different between the groups(p>0.05). However, after 90 and 120 minutes, reduction rate of each group was significantly different(p<0.05).

• Journal of Animal Science and Technology
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• v.46 no.2
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• pp.273-282
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• 2004

Composting animal manure is one of feasible treatments that reserves some portion of nutrients of manure. Although the application of compost to arable land has many advantages, the repeated cultivation of the agriculture land will accumulate the level of heavy metals in the soil which is potentially hamful to people and animals. Therefore it is important to know the characteristics concentration and species of heavy metals in a variety of chemical fonns than just total content of the metal. Because the metals in different forms have different mobilities and bioavailabilites. The aim of this study was to examine the total content and the chemical forms of the heavy metals; Cr, Ni, Cu, Zn, As, Cd and Pb in the animal manure composted with sawdust or rice hull as a bulking agent. A total of 75 compost samples were collected throughout the country and classified into the three groups in accordance with the characteristics of raw materials: swine manure, poultry manure, and mixed(swine + poultry + cattle)manure. The compost samples were analyzed for total metal content and fractionated by sequential chemical extractions to estimate the quantities of metals: exchangeable, adsorbed, organically bound, carbonate and residual. The results showed that the heavy metal concentrations in all compost samples were lower than the maximum acceptable limits by the Korea Compost Quality Standards. The concentrations of heavy metals in the swine manure compost were higher than those of both the poultry and the mixed manure compost except for Cr. Zn and Cu concentrations of three different compost ranged from 157 to 839 mg Zn/kg DM(dry matter) and from 47 to 458 mg Cu/kg DM, depending on the composition of animal manures. The predominant forms for extracted metals were Cr, Ni, Zn, As and Ph, residual; Cu, organic; and Cd, carbonate. The results suggested that the legal standards for composts should be reexamined to revise the criteria on the total metal content as well as metal speciation.

• Korean Journal of Microbiology
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• v.40 no.1
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• pp.29-36
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• 2004

The purpose of this work was to investigate the relationships between acrylamide degradation by Pseudomonas sp. JK-7 and several relevant physicochemical environment parameters. In initial experiments, the bacterial culture, strain JK-7 isolated from paddy soil sample was developed to grow aerobically with acrylamide as the sole source of carbon and nitrogen. The bacterium was identified as genus Pseudomonas in the basis of use BIOLOG test, and designated as Pseudomunas sp. JK-7. Strain JK-7 could degrade 50 mM acrylamide completely within 72 hours of incubation. Major intermediates resulting from acrylamide degradation were not detected with the HPLC methodology except acrylic acid which appeared to accumulate transiently in the growth medium. The pH increased from 7.0 to 8.7 with complete degradation of the initial 50 mM acrylamide within 72 hours of incubation. pH control in the range of 5 to 9 influenced the growth of JK-7 and acrylamide degradation, whereas it was not examined the growth and degradation at pH 3 or pH 11, respectively. The effect of supplemented carbons (e.g., glucose, fructose, citrate, succinate) on the acrylamide degradation by the test culture of JK-7 was evaluated. The results indicated that the addition of carbons accelerated the bacterial growth and acrylamide degradation compared to those in the absence of supplemented carbons. The effect of supplemented nitrogens on the degradation was monitored. Increasing concentrations of yeast extract resulted in higher growth yield, based on the turbidity measurement, and complete degradation of acrylamide. However, acrylamide degradation was essentially uninfluenced by the addition of $(NH_{4})_{2}SO_{4}$, $NH_4Cl$ or urea. Addition of $AgNO_3$, $CuSO_4$ or $HgCl_2$ except $ZnSO_4$ in the test culture inhibited the degradation of acrylamide and growth of JK-7.

• The Korean Journal of Mycology
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• v.23 no.1 s.72
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• pp.92-104
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• 1995

Ten species of Cordyceps species were collected throughout Kangwon province including Chuncheon Dongsanmyun KNU forest experiment from June to September, 1993. Collected Cordyceps species were identified as Cordyceps militaris, C. roseostromata, C. kyushuensis, C. scarabaeicola, Phytocordyceps ninchukiospora, C. nutans, Paecilomyces tenuipes, C. sphecocephala, Hymenostilbe odonatae, Torrubiella sp.. C. militaris, type species of Cordyceps species, was mainly formed on pupae of Lepidoptera and found after the rainy season around July. Fruiting body of C. roseostromata was morphologically similar to those of C. militaris, but relatively small in size and they were also found on lawn or pupa of Lepidoptera. Fruiting body of C. scarabaeicola was found on adult Scarabaeidae specifically and collect fruiting bodies of C. kyushuensis were on larva of moth. C. nutans and C. sphecocephala had host specificity on Hemiptera and Hymenoptera, respectively. Each species formed elliptical fertile part attach to the slim and carneous stalk and they were collected the most in specimen number through whole season of the summer. Ascospore of Phytocordyceps ninchukiospora on seed was characterized by two viable, multiseptate, fusiform units linked end-to-end by a long, filiform connective. Paecilomyces tenuipes, imperfect stage of the genus Cordyceps is multi-infective fungi that attack all stages of all groups of insects. Hymenostilbe odonatae attacks only adult Odonata and Torrubiella sp. formed on spider was difficult to collect because it was found the back side of leaf. As results of cultural test PDA medium showed the best mycelial growth. In the experiment of effect of the acidity inside of the media, C. militaris was good on pH 5, C. nutans and Phytocordyceps ninchukiospora were good on pH 6 and Paecilomyces tenuipes was on pH 7 and C. scarabaeicola was on pH 9. All isolates tested showed the best mycelial growth at $20^{\circ}C$. Morphologically similar isolates were used to analyze protein banding pattern among and within species. As a result, C. militaris, C. roseostromata and C. kyushuensis were clustered into close species and C. scarabaeicola and Phytocordyceps ninchukiospora were relatively distant from those species.

• Journal of Life Science
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• v.23 no.2
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• pp.197-206
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• 2013

The present study investigated whether leukemia-maintaining cells reside in a differentiation-resistant fraction using a megakaryocytic differentiation model of K562 cells. Treatment with phorbol-12-myristate-13-acetate (PMA) significantly inhibited the colony-forming efficiency of the K562 cells. At a PMA concentration of 1 nM or higher, colony was not formed, but approximately 40% of K562 cells still survived in soft agar. Approximately 70% of colony-forming cells that were isolated following the removal of PMA after exposure to the agent were differentiated after treatment with 10 nM PMA for 3 days. The differentiation rate of the colony-forming cells was gradually increased and reached about 90% 6 weeks after colony isolation, which was comparable to the level of a PMA-treated K562 control. Meanwhile, imatinib-resistant variants from the K562 cells, including K562/R1, K562/R2, and K562/R3 cells, did not show any colony-forming activity, and most imatinib-resistant variants were CD44 positive. After 4 months of culture in drug-free medium, the surface level of CD44 was decreased in comparison with primary imatinib-resistant variants, and a few colonies were formed from K562/R3 cells. In these cells, Bcr-Abl, which was lost in the imatinib-resistant variants, was re-expressed, and the original phenotypes of the K562 cells were partially recovered. These results suggest that leukemia-maintaining cells might reside in a differentiation-resistant population. Differentiation therapy to eliminate leukemia-maintaining cells could be a successful treatment for leukemia if the leukemia-maintaining cells were exposed to a differentiation inducer for a long time and at a high dose.

• Journal for History of Mathematics
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• v.22 no.2
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• pp.27-52
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• 2009

This article discusses the contributions of the leader Oswald Veblen, who was the president of AMS during 1923-1924. In 2006, Korea ranked 12th in SCIE publications in mathematics, more than doubling its publications in less than 10 years, a successful model for a country with relatively short history of modern mathematical research. Now there are 192 four-year universities in Korea. Some 42 of these universities have Ph.D. granting graduate programs in mathematics and/or mathematical education in Korea. Rapid growth is observed over a broad spectrum including a phenomenal performance surge in International Mathematical Olympiad. Western mathematics was first introduced in Korea in the 17th century, but real significant mathematical contributions by Korean mathematicians in modern mathematics were not much known yet to the world. Surprisingly there is no Korean mathematician who could be found in MaC Tutor History Birthplace Map. We are at the time, to have a clear vision and leadership for the 21st century. Even with the above achievement, Korean mathematical community has had obstacles in funding. Many people thinks that mathematical research can be done without funding rather unlike other science subjects, even though they agree fundamental mathematical research is very important. We found that the experience of early American mathematical community can help us to give a vision and role model for Korean mathematical community. When we read the AMS Notice article 'The Vision, Insight, and Influence of Oswald Veblen' by Steve Batterson, it answers many of our questions on the development of American mathematics in early 20th century. We would like to share the story and analyze its meaning for the development of Korean Mathematics of 21st century.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.4
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• pp.385-390
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• 1999

HPLC method usually has been used for the determination of ATP and its related compounds in fish muscle and fish sauce. But, total amount of ATP related compounds in fish sauce is determined less than that of fish muscle. In order to establish the extract analysis method for ATP related compounds in fish sauce, a new enzymatic method was developed and compared with existing HPLC method. Fish sauce was extracted with chilled perchloric acid and neutralized to Ph 7.0 with potassium hydroxide solution, the extract was used as sample analyzed by HPLC as usual. On the other hand, for sample analyzed by enzymatic method, 1 ml extract solution was pipetted into test tube. To the tube, 0.5ml of mixed suspension adenosinedeaminase (4U), nucleosidephosphorylase (0.02U) and xanthineoxidase (0.03U) suspended in 2.0ml of 1/15 M sodium phosphate buffer solution pH 7.6 and 1.5ml deionized water wereadded for the decomposition of IMP, HxR and Hx to uric acid at $37^{\circ}C$ for 40 minutes. Total uric acid was determined by measuring optical density at 290nm. In HPLC method, salt decreased the total amount of ATP related compounds by $13.6\~16.2\%$ at $2.5\%$ concentration, but no effect in enzymatic method. IMP, HxR and Hx were detected at 254nm, while uric acid at only 290nm. The ratio of the total amount of ATP related compounds by HPLC method was about $45\%$ of that by enzymatic method in fish sauce. Form these results, enzymatic method is more accurate and simple than HPLC method for analysis of ATP related compounds in fish sauce.