• Journal of the Korean Chemical Society
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• v.40 no.1
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• pp.50-58
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• 1996

In the presence of metal ions(Co(Ⅱ), Ni(Ⅱ), Sr(Ⅱ), Cu(Ⅱ), Fe(Ⅲ), U(Ⅵ)), the sedimentation of humic acid was increased at constant pH with increasing metal concentration and the strength was increased in the following order: Sr < Ni < Co < Cu < Fe < U. At constant metal concentration, Cu(Ⅱ), Ni(Ⅱ), and Co(Ⅱ) ions caused an increase in sedimentation of humic acid as the solution pH increased, whereas Fe(Ⅲ) and U(Ⅵ) ions caused a decrease. Sr(Ⅱ) ions did not affect the sedimentation even with the variation of pH. The analysis of FT-IR spectra for the sediments prepared from the reaction between humic acid and metal ions showed that metal ions were bound to humic acid to form complexes, suggesting that the metal complexation plays an important role in the sedimentation of humic acid.

• Bulletin of the Korean Chemical Society
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• v.16 no.2
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• pp.193-195
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• 1995

• YAKHAK HOEJI
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• v.55 no.3
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• pp.227-233
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• 2011

We previously reported the protein isolated from Coptidis Rhizoma (CRP), which has antifungal activity against a fungal pathogen, Candida albicans. In the current study, we investigated what portion in the CRP is responsible for the antifungal activity. For the investigation, the CRP was fractionated on a Shepadex G-50 column. Data resulting from the fractionation, seven fractions were obtained. Fractions (Fr.) I, II, and III eluted initially from the column showed no inhibitory effect on the growth of C. albicans, whereas Fr. IV, V, and VI eluted later revealed inhibition of the growth, and Fr. IV and VI showed potent antifungal activity by broth susceptibility analysis. However, Fr. VI was contained in the CRP more than Fr. IV, which led us to select the VI for the following experiments. In a murine model of a subcutaneous candidiasis caused by C. albicans, the Fr. VI displayed a therapeutic effect on nude mice pretreated with anti-neutrophil monoclonal antibody (RB68C5) and then infected subcutaneously with live C. albicans. At day 16, these mice were healed almost up to 78% of the infected area when compared to infected area of control nude mice that received diluent (Dulbecco's Phosphate-Buffered Saline; DPBS), instead of the Fr. VI (P<0.01). The Fr. VI blocked hyphal formation from blastoconidial form of C. albicans (P<0.01), which might prevent penetration of hyphae to the deeper site of skin and thus helps the healing. In the ionic strength test, the effect of Fr. was influenced by $Ca^{2+}$ ion just like other known antimicrobial peptides, but the influence was affected at an extremely high concentration such as 500 mM. Thus, such ion-concentration is considered to be meaningless in the clinical situation. Considering all data together, Coptidis Rhizoma is appeared to produce an antimicrobial peptide that has therapeutic effect on subcutaneous infection caused by C. albicans.

• Journal of the Korean Chemical Society
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• v.27 no.2
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• pp.157-164
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• 1983

N-Methylidene-2,6-diethylaniline (III) was prepared by the reaction of 2,6-diethylaniline (II) with an excess paraformaldehyde. The protons of N=$CH_2$in the compound III exhibited a second order NMR spectrum. The compound III reacted with bifunctional chlorocarbonylsulfenyl chloride(IV) to give N-(chloromethyl)-N-(2,6-diethylphenyl)-carbamoylsulfenyl chloride(V). The reaction of the compound V with various alcohols resulted in the formation of Alkyl N-(chloromethyl)-N-(2,6-diethylphenyl)-carbamoylsulfenate esters(VI${\sim}$XVI) in 71${\sim}$95% yields. The compound VI${\sim}$XVI decomposed gradually, but the thermal rearrangement of S-O bonding to S=O bonding was not found. The nucleophilic attack of an excess alcohol to the compound Ⅴ was made on both divalent sulfur and ${\alpha}$-carbon of N-chloromethyl group. The corresponding substituted products(XVII, XVIII) had considerable stability.

• Economic and Environmental Geology
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• v.21 no.3
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• pp.257-268
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• 1988

The Mugeug gold deposits is consisted of more than fourteen gold and silver-bearing quartz veins emplaced in Mesozoic granodiorite mass. In the Samhyungje vein, one of the representative vein in the mine, six stages of mineralizatidns are recognized: Stage I, deposition of base-metal sulfides and gray quartz; stage II, deposition of base-metal sulfides, electrum and white quartz with pinkish tint; stage m, deposition of base-metal sulfides and dark gray quartz; stage N, deposition of native silver, argentite, Ag-tetrahedrite, polybasite, arsenpolybasite and quartz; stage V, deposition of nearly barren quartz; stage VI, deposition of transparent quartz veinlets with minor pyrite. Ag contents of electrum increase steadily from stage II to stage N; 57.25-61.44 atom. % for stage II, 62.85-69.66 atom. % for stage m, 69.79-74.12 atom. % for stage N. Homogenization temperatures of fluid inclusions are as follows; stage II, from $194^{\circ}$ to $287^{\circ}C$; stage V, from $137^{\circ}$ to $171^{\circ}C$, stage VI, from $192^{\circ}$ to $232^{\circ}C$. Salinities of fluid inclusions range from 3.7 to 7.9 wt.% equivalent NaCl in stage II and from 0.8 to 4.3 wt.% equivalent Nael in stage V. Ore mineralogy suggest that temperature and sulfur fugacity declined steadily from $290^{\circ}$ to $150^{\circ}C$ and from $10^{-10.5}$ to $10^{-19.0}$atm. through stage II into stage N. Fluid pressure during stage II inferred from data of mineral assemblages and fluid inclusions is 370bar.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.1
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• pp.90.2-90.2
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• 2015

We present the high-resolution spectrum of the S-type symbiotic star V455 Sco obtained with the Dupont telescope in 2014 June. We note that the Raman-scattered O VI ${\lambda}1032$ at $6825{\AA}$ exhibits a triple-peak profile. Adopting an accretion disk model with an additional contribution from a collimated bipolar outflow, we attempt to fit the profile. We propose that the blue and central peaks are formed via Raman-scattering of O VI line photons from the accretion flow and that the bipolar flow is responsible for the remaining red peak. It is also noted that V455 Sco exhibits the Raman-scattered He II features blueward of $H{\alpha}$ and $H{\beta}$.

• Journal of environmental and Sanitary engineering
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• v.23 no.2
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• pp.47-53
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• 2008

The ion exchange resins have been synthesized from chloromethyl styrene (dangerous matter) 1, 4-divinylbenzene(DVB) with 1%, 5%, and 15%-crosslinked and macrocyclic ligand of cryptand type by copolymerization method and the adsorption of uranium(VI), cobalt(II) and europium(III) ions have been investigated in various experimental conditions. The correlation between the adsorption characteristics of rare earths and transition metal on the resins and stability constants of complexes with macrocyclic ligand have been examined. The uranium ion was not adsorbed on the resins below pH 2.0, but the power of adsorption of uranium ion increased rapidly above pH 3.0. The adsorption power was in the order of 1%, 5% and 15%-crosslinked resin, but adsorptive characteristics of resins decreased in proportion to the order of dielectric constants of solvents.

• Journal of environmental and Sanitary engineering
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• v.15 no.1
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• pp.77-87
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• 2000

Several new ion exchange resins have been synthesized from chloromethyl styrene-l,4-divinylbenzine with 1%, 2%, 10% and 20%-crosslink and macrocyclic ligands of cryptand type by interpolymerization method. The adsorption characteristics and the pH, time, solvents and concentration dependence of the adsorption of metal ions by this resin were studied. The correlation between the separation characteristics of uranium and transition metal on the resins and the stability constants of complexes with macrocyclic ligands have been examined. The resins were very stable in both acidic and basic media and have good resistance to heat. The $UO_2^{2+}$ was not adsorbed on the resins below pH 3.0, but the power of adsorption of $UO_2^{2+}$ increased rapidly above pH 4.0. The optimum equilibrium time for adsorption of metallic ions was two hours and adsorptive power decreased in proportion to crosslink size of the resins and order of dielectric constants of solvents used and the selective sequence for metal cations was in the order of $UO_2^{2+}$, $Ni{2+}$ and $Nd{3+}$.

• Restorative Dentistry and Endodontics
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• v.8 no.1
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• pp.107-113
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• 1982

The purpose of this study was to observe the tensile strength of composite resins to etched dentin surface with the various methods of placing bonding agent before composite resin or placing composite resin alone. Recently extracted 60 maxillary incisors were chosen. These were divided into 6 groups: Group I : Immediate Silar adaptation to the etched dentin surface with 37% phosphoric acid for 60 seconds without bonding agent. Group II : Immediate Silar adaptation to the etched dentin surface with 37% phosphoric acid for 60 seconds with bonding agent. Group III : Silar adaptation to the etched dentin surface with 37% phosphoric acid for 60 seconds after 5 minutes of bonding agent. Group IV : Immediate Enamelite adaptation to the etched dentin surfaces with 50% phosphoric acid for 120 seconds without bonding agent. Group V : Immediate Enamelite adaptation to the etched dentin surface with 50% phosphoric acid for 120 second s with bonding again. Group VI : Enamelite adaptation to the etched dentin surface with 50% phosphoric acid for 120 seconds after 5 minutes of bonding agent. All specimens were immersed in water at $37^{\circ}C$ for 24 hours before testing. The results were as follows: 1. The tensile strength of powder/liquid composite resin system was higher than that of pastel paste composite resin system. 2. The tensile strength of the composite resin group II, III, V, & VI with bonding agent was higher than that of the composite resin group I & IV without bonding agent. 3. The tensile strength of the composite resin group III & VI after 5 minutes added to bonding agent was higher than that of the composite resin group II & V immediately added to bonding agent.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.213-213
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• 2013

화합물 반도체 양자점(Quantum dots; QDs)은 높은 효율의 광전자 소자에 적용할 수 있기 때문에 이분야에 대한 연구가 활발히 진행되고 있지만 주로 III-V 족 화합물 반도체에 대한 연구가 주를 이룬 반면 II-VI 족 화합물 반도체에 대한 연구는 아직 미흡하다. 하지만 II-VI 족 화합물 반도체는 III-V 족 화합물 반도체와 비교했을 때 더 큰 엑시톤 결합에너지(exciton binding energy)를 가지는 우수한 특성을 보이고 있으며 이러한 성질을 가지는 II-VI 족 화합물 반도체 중에서도 넓은 에너지 갭을 가지는 $Cd_xZn_{1-x}Te$ 양자점은 녹색 영역대의 광전자 소자로서 활용되고 있다. 현재 대부분의 $Cd_xZn_{1-x}Te$ 양자점 구조는 기판과 완충층 (buffer layer) 사이의 작은 격자 부정합(lattice mismatch) 때문에 GaAs 기판을 이룬 반면 Si기판을 이용한 연구는 미흡하다. 하지만 Si 기판은 GaAs 기판에 비해 값이 싸고, 여러 분야에 응용이 가능하며 대량생산이 가능하다는 이점을 가지고 있어 초고속, 초고효율 반도체 광전소자의 제작을 가능케 할 것으로 기대된다. 또한 양자점의 고효율 광전소자에 응용을 위해서는 Si 기판 위에 양자점의 크기를 효율적으로 조절하는 연구 뿐 아니라 양자점의 크기에 따른 운반자 동역학에 대한 연구도 중요하다. 본 연구에선 분자선 에피 성장법(Molecular Beam Epitaxy; MBE)을 이용하여 Si 기판위에 성장한 $Cd_xZn_{1-x}Te/ZnTe$ 양자점의 크기에 따른 광학적 특성을 연구하였다. 저온 광 루미네센스 (PhotoLuminescence; PL) 측정 결과 양자점의 크기가 증가함에 따라 더 낮은 에너지영역으로 피크가 이동하는 것을 확인하였다. 그리고 시분해 광루미네센스 측정 결과 $Cd_xZn_{1-x}Te/ZnTe$ 양자점의 크기가 증가함에 따라 소멸 시간이 긴 값을 갖는 것을 관찰 하였는데, 이는 양자점의 크기가 증가함에 따라 엑시톤 진동 세기가 감소하였기 때문이다. 또한 온도 의존 광루미네센스 측정 결과 양자점의 크기가 증가함에 따라 열적 활성화 에너지가 증가하는 것을 관찰 하였는데, 이는 양자점의 운반자 구속효과가 증가하였기 때문이다. 이와 같은 결과 Si 기판 위에 성장한 $Cd_xZn_{1-x}Te/ZnTe$ 양자점의 크기에 따른 광학적 특성에 대해 이해 할 수 있었다.