• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.115-115
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• 2015

Many efforts have been devoted on chemical modification of graphene layer to modulate its electrical properties. In the previous report, laser irradiation on the CYTOP (Amorphous Fluoropolymer) covered graphene layer induces chemical modification wherein carbon fluoride is formed on the graphene surface. This results in the insulating I-V characteristics, which have been attracting much research interests on it. However, the direct analytical evidence of the fluoride formation on graphene surface is not yet studied. In this work we investigated what happened on the CYTOP/graphene interface during photon irradiation using spatially resolved photoemission spectroscopy method. It is found that the soft x-ray (614 eV) induces desorption of fluoride atoms from the CYTOP and change di-fluoride form to mono-fluoride. As the photo-induced fluorine desorption is continue strong dipole field generated by initial di-fluoride forms is gradually decreased, resulting in the overall binding energy shift of the C 1s core levels. Both photo-modified CYTOP and CYTOP starts to desorb above $286^{\circ}C$ (~ 0.047 eV), which means that no strong chemical interaction between CYTOP and graphene is established.

• The Journal of the Korean dental association
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• v.12 no.10
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• pp.767-770
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• 1974

A 12 years old patient having rampant dental caries on permanent dentition has been treated under operative procedures. In addition to this operative treatment the nutritional survey and the caries activity was checked, and performed the oral hygiene instruction to the patient. As the consequences of above procedures the following results were obtained: 1. The familial history and eating habits checkings were helpful for better dental health guide and caries control. 2. The restriction of mono & disaccharide intake and topical application of 8% stannous fluoride at least two times revealed excellent control effect for recurrent dental caries.

• Journal of the Korean Chemical Society
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• v.13 no.1
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• pp.68-74
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• 1969

Flourination of Ethyl, ${\alpha},{\beta$}-dichloro-${\beta$}-phenyl propionate, Ethyl ${\alpha},{\beta$}-dibromo ${\beta$}-phenyl propionate, Ethyl ${\alpha},{\beta$}-dichloro ${\beta$}-(p-chloro-phenyl) propionate, and dibromostyrene by potassium fluoride were investigated in presence of dimethyl formamide, diethylene glycol, and diethylene glycol monomethyl-ether. The reactivity of these organic halogen esters and hydrocarbons towards potassium fluoride was checked further by means of radioactive fluorine-18. tracer. Generally, the reaction gave monofluoride together with dehalogenated olefin. The formation of olefine was increased when the reaction was done at high reaction temperature in presence of diethylene glycol, whereas the lower reaction temperature in presence of diethyleneglycol monomethyl ether favored the formation of mono fluoride in a good yield. The procedures and methods of the identification of monofluorides were described and the feasibility of this reaction of fluorine containing ester including the F-18 labelled compounds was discussed.

• The korean journal of orthodontics
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• v.27 no.5 s.64
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• pp.781-789
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• 1997

The purpose of this study was to evaluate the effects of fluoride relasing orthodontic sealant on the shear bond strength of light-and chemical-cured orthodontic rosins, to compare the shear bond strenth with light-and chemical-cured orthodontic resins, and to identify the changes of shear bond strength by rebonding in vitro. The brackets were divided into eight groups. Each group of metal brackets had different bonding mechanisms with adhesives. Group A : Transbond only Group B : Mono-Lok 2 only Group C : Light cured FluoroBond+Transbond Group D : Light cured FluoroBond+Mono-Lok 2 Group E : Transbond only(rebonded) Group F : Nomo-Lok 2 only(rebonded) Group G : Light cured FluoroBond+Transbond(rebonded) Group H : Light cured FluoroBond+Mono-Lok 2(rebonded) 65 extracted human premolars were prepared for bonding and 65 metal brackets for each group were bonded to prepared enamel surfaces of buccal surfaces as the above prescription. 24 hours bonding after, the Instron universal testing machine was used to test the shear bond strength of metal brackets to enamel. After debonding, same kind of metal brackets for each group were rebonded to prepared enamel surfaces of buccal surfaces to test the shear bond strength at the rebonding to enamel. Statistical analysis of the data was carried out Student's t-test ANOVA test, and Scheffe test using $SPSS/PC^+$ The results were as follows : 1. The order of shear bond strength was Group B(11.84MPa), Group A(10.75MPa), Group, D(9.69MPa), and Group C(9.39MPa)in lst bonded groups. 2. The order of shear bond strength was Group E(7.40MPa), Group G(6.48MPa), Group F(5.89MPa), and Group H(5.15MPa) in rebonded groups. 3. The shear bond strength of chemical cured orthodontic rosins had higher than that of light-cured orthodontic resins in all groups, but there was no statistical significance between groups(P>0.05). 4. In rebonded groups, the shear bond strength of light cured orthodontic rosins had higher than that of chemical cured orthodontic resins, but there was no statistical significance between groups(P>0.05). 5. The shear bond strength of all rebonded groups progressively decreased than that of 1st bonded groups, and there was statistical significance between groups(p<0.05, p<0.001).

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.198.1-198.1
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• 2014

Many efforts have been devoted on chemical modification of graphene layer to modulate its electrical properties. In the previous report, laser irradiation on the CYTOP(perfluoropolymer) doped graphene layer induces chemical modification of it, resulting in the insulating I-V characteristics. While the results strongly denoted C-F bond formation after irradiation, the detailed process of photo-induced chemical change is not known yet. To probe this, we utilized synchrotron based SPEM (scanning photoelectron emission spectroscopy) in NSRRC, Taiwan. We irradiate the sample by photon of 614 eV in a stepwise manner as a function of time. As photon irradiation increased, difluoride moieties in the CYTOP was broken, and then formed mono-fluoride with carbon atoms consisting graphene layer.

• Bulletin of the Korean Chemical Society
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• v.11 no.1
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• pp.65-69
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• 1990

The nucleophilic substitution reactions of naphthalene-1,5-disulfonyl chloride and 4-fluorosulfonylbenzenesulfonyl chloride with p-substituted anilines and methyl substituted pyridines in methanol-acetonitrile mixtures and hydrolyses of those disulfonyl halides have been studied by means of conductometric and polarographic methods. A large difference in the selective parameter, ${\rho}_N$ between mono-sulfonyl chloride and disulfonyl halide can be taken as an evidence that the second $SO_2Cl$ grolup of naphthalene-1,5-disulfonyl chloride also takes part in the reaction in contrast to sulfonyl fluoride in 4-fluorosulfonylbenzenesulfonyl chloride, which only acts as a substituent in the nucleophilic substitution reaction.

• Biomedical Science Letters
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• v.6 no.4
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• pp.261-268
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• 2000

Fibrinolytic enzyme (FE-2) was purified from the fruiting bodies of Tricholoma saponaceum using DEAE-Cellulose chromatography and Mono-S column chromatography, The enzyme has a molecular weight of 18.23 kDa and include Zn$^{2+}$ ion as found by ICP/MS. The N-terminal amino acid sequence of the enzyme was A-L-Y-V-G-X-S-P-X-Q-Q-S-L-L-V It has a pH optimum at pH 7.5, suggested that FE-2 was a neutral pretense. The activity of FE-2 was highly inhibited by EDTA and 1,10-phenanthroline, indicating that the enzyme is a metalloprotease. The activity of FE-2 was increased by $Mg^{2+}$, Zn$^{2+}$, Fe$^{2+}$, and Co$^{2+}$, but the enzyme activity was totally inhibited by Hg$^{2+}$. No inhibition was found with PMSF, E-64, pepstatin and 2-mercaptoethanol. The enzyme hydrolyzed both $A\alpha$ and B$\beta$ chains of human fibrinogen. The $\gamma$ chain was resistant to hydrolysis by FE-2.

• BMB Reports
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• v.32 no.6
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• pp.579-584
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• 1999

Mantis egg fibrolase (MEF-3) was purified from the egg cases of Tenodera sinensis using ammonium sulfate fractionation, gel filtration on Bio-Gel P-60, DEAE Affi-Gel blue gel affinity chromatogragphy, and MONO-Q anion-exchange chromatography. This protease had a molecular weight of 35,600 Da as determined by SDS-polyacrylamide gel electrophoresis under reducing conditions and its isoelectric point was 6.0. The N-terminal amino acids sequence was Ala-Thr-Gln-Asp-Asp-Ala-Pro-Pro-Gly-Leu-Ala-Arg-Arg. This sequence was 80% homologous to the serine protease from Tritirachium album. MEF-3 readily digested the ${\alpha}$-and ${\beta}$-chains of fibrinogen and more slowly the ${\gamma}$-chains. It showed strong proteolytic and fibrinolytic activities. Phenylmethanesulfonyl fluoride and chymostatin inhibited its proteolytic activity, while EDTA, EGTA, cysteine, ${\beta}$-mercaptoethanol, elastinal, tosyl-lysine chloromethylketone, and tosyl-amido-2-phenylethyl chloromethyl ketone did not affect its proteolytic activity. Among the chromogenic protease substrates, the most sensitive one to the hydrolysis of MEF-3 was benzoyl-Phe-Val-Arg-p-nitroanilide. Based on these experimental results, we speculated that MEF-3 is a serine protease with a strong fibrin(ogen)olytic activity.

• Fisheries and Aquatic Sciences
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• v.2 no.2
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• pp.218-225
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• 1999

A protease without tryptic and chymotryptic activities was purified from the hepatopancreas of shrimp, Penaeus orientalis, using Q-Sepharose ionic exchange, benzamidine Sepharose-6B affinity, Mono-Q, and gel chromatography. Molecular weight (M.W.) of the protease was estimated to be 27kDa by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS­PAGE). The amino acid composition of the protease was different from that of protease from P. japonicus or trypsin from P. orientalis. The protease was completely inhibited by benzamidine, $N\alpha-p-tosyl-L-lysine$ chloromethyl ketone (TLCK), and phenylmethylsulfonyl fluoride (PMSF) and was not affected by leupeptin, pepstatin, N-tosyl-L-phenylalanine chloromethyl ketone (TPCK), iodoacetate, and ethylenediamine tetra acetate (EDTA). The enzyme did not have any activity against Na-benzoyl-DL-arginine p-nitroanilide (BAPNA) or N-benzoyl-L-tyrosine ethyl ester (BTEE) which are specific substrates of trypsin and chymotrypsin, respectively. However, the protease showed hydrolytic activity for a carboxyl terminal of Tyr, Trp, Phe, Glu, and Cys.

• Parasites, Hosts and Diseases
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• v.41 no.4
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• pp.189-196
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• 2003

In order to evaluate the possible roles of secretory proteases in the pathogenesis of amoebic keratitis, we purified and characterized a serine protease secreted by Acanthamoeba lugdunensis KA/E2, isolated from a Korean keratitis patient The ammonium sulfate-precipitated culture supernatant of the isolate was purified by sequential chromatography on CM-Sepharose, Sephacryl S-200, and mono Q-anion exchange column. The purified 33 kDa protease had a pH optimum of 8.5 and a temperature optimum of $55^{\circ}C$. Phenylmethylsulfonylfluoride and 4-(2-Aminoethyl)-benzenesulfonyl-fluoride, both serine protease specific inhibitors, inhibited almost completely the activity of the 33 kDa protease whereas other classes of inhibitors did not affect its activity. The 33 kDa enzyme degraded various extracellular matrix proteins and serum proteins. Our results strongly suggest that the 33 kDa serine protease secreted from this keratopathogenic Acanthamoeba play important roles in the pathogenesis of amoebic keratitis, such as in corneal tissue invasion, immune evasion and nutrient uptake.