The Insect Peptide Coprisin Prevents Clostridium difficile-Mediated Acute Inflammation and Mucosal Damage through Selective Antimicrobial Activity

Kang, J.K.,Hwang, J.S.,Nam, H.J.,Ahn, K.J.,Seok, H.,Kim, S.-K.,Yun, E.Y.,Pothoulakis, C.,Lamont, J.T.,Kim, H. AMERICAN SOCIETY FOR MICROBIOLOGY 2011 Antimicrobial agents and chemotherapy Vol.55 No.10

Di(2-pyridyl)ketone stabilized titanium dioxide nanoparticles for the room temperature processed electron transporting layer in organic photovoltaics

Hwang, H.,Yoon, S.,Seok, J.,Kim, K. Elsevier Science 2016 ORGANIC ELECTRONICS Vol.28 No.-

Monodisperse TiO<SUB>2</SUB> nanoparticles are obtained through hydrolysis of titanium butoxide in the presence of di(2-pyridyl)ketone (DPK) and para-toluenesulfonic acid. The DPK ligand stabilized the surface of the TiO<SUB>2</SUB> nanoparticle through complexation with TiO<SUB>2</SUB>. DPK stabilized TiO<SUB>2</SUB> (TNP-DPK) can be dispersed without aggregation in alcoholic solutions at concentrations higher than 1 M. The synthesized particles have 4-5 nm size and spherical shape at amorphous phase. The atomic force microscope image reveals that only 0.1 wt% of TNP-DPK solution can form a conformal and dense film on top of the active layer. The TNP-DPK solution is used for an electron transporting layer (ETL) in organic photovoltaics (OPV) that utilizing poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b;4,5-b']dithiophene-2,6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene-)-2-carboxylate-2-6-diyl)] (PTB7-Th) as a photoactive layer. The power conversion efficiency of the OPV is significantly improved from 7.18% to 9.08% by inserting the TNP-DPK layer between photoactive layer and Al electrode. Based on the internal quantum efficiency and transient photo voltage experiments, the TNP-DPK layer is found to improve the charge collection efficiency and reduce the charge recombination at the active layer/electrode interface. These results clearly show that the solution processed TNP-DPK layer can play a role as an efficient ETL in OPVs.

Formulation of Nanoparticle Containing Everolimus Using Microfluidization and Freeze-Drying

Seok, S. H.,Kang, S.-Y.,Seo, J.-W.,Kim, S.-H.,Hwang, K.-M.,Park, E.-S. Pharmaceutical Society of Japan 2016 Chemical & pharmaceutical bulletin Vol. No.

<P>The aims of this study were to improve in vitro dissolution property of poorly water-soluble everolimus (EVR) for enhanced bioavailability without using organic solvents and characterize the effects of microfluidization and freeze-drying on physicochemical properties of EVR nanosuspension and nanoparticle, respectively. EVR nanosuspension was prepared using microfluidization with various types and concentrations of stabilizers. After that, it was solidified into nanoparticle using freeze-drying with various concentrations of xylitol, a cryoprotectant. The particle size, zeta potential, physical stability, and chemical stability of EVR nanosuspension and nanoparticle were measured. In vitro release of EVR nanoparticle was also measured and compared with that of physical mixture. Zero point five percent (w/w) poloxamer 407 (P407) was chosen as the stabilizer considering particle size, zeta potential, and yield of EVR nanosuspension. Freeze-drying with 1% (w/w) xylitol improved both physical and chemical stability of EVR nanoparticle. In vitro release test showed improved dissolution property compared to that of physical mixture, implying enhanced bioavailability.</P>

가성 다혈증이 동반된 확장성 심근병증 1예

황동인,김종형,이덕기,이동주,신윤,김석은,박석준,한상국 대한순환기학회 2000 Korean Circulation Journal Vol.30 No.5

Thermal Spray of Nanostructured Materials

Hwang S.Y.,Kim J.H.,Kim H.J.,Seong B.G.,Jun H.W.,Lee H.W.,Seok H.K.,Lee C.,Yang H.,Baik K.H. 한국분말야금학회 2006 한국분말야금학회 학술대회논문집 Vol.2006 No.1

The Association between Childhood Asthma and Residential Environmental Risk Factors through Case-Control Study in Andong, Korea

Seok J. Yoon,H. K. Lin,G. Chen,Gyuseok Hwang 서울대학교 보건환경연구소 2013 보건학논집 Vol.50 No.1

Using ISAAC questionnaire, we surveyed the childhood asthma prevalence and related socioeconomic and residential environment on 887 elementary schoolchildren in Andong, Korea. We selected asthma case group (29) and control group (26) and performed the exposure assessment for the personal exposure for the personal exposure for the VOCs (Volatile Organic Compounds) and formaldehyde level for 3 days. As a result, 814 schoolchildren completed the questionnaire. It was found that the asthma prevalence was 19.9% and gender (male, OR; Odds Ratio=1.55), age (younger, OR=1.60), family history of asthma (OR=3.70), passive smoking (OR=1.53), and odor from nearby house (OR=2.01) were affective factors. There was no significant difference between the case and control groups in VOCs and formaldehyde exposure level. In the logistic regression analysis, family income (aOR; adjusted OR =3.20, 95% CI=1.41-7.24) and amount of house sunlight (aOR=2.14, 95% CI; Confidence Interval =1.00-4.58) were significant after adjusting gender, age, and family history of asthma. In conclusion, socioeconomic factors including family income and residential environmental factors such as passive smoking, odor from nearby household, and amount of house sunlight are associated with the prevalence of childhood asthma.

직업적 연폭로에서 혈중 연량 수준에 따른 선별검사로서의 혈중 ZPP 검사의 타당도

한구석,안현철,김용배,리갑수,김화성,황규윤,장봉기,이성수,안규동,이병국 순천향대학교 산업의학연구소 1999 순천향산업의학 Vol.5 No.1

In order to evaluate the validity of current screening criteria of lead exposure and to provide effective information for the better health management of lead workers, author investigated the interrelationship between blood lead and blood zinc protoporphyrin(ZPP) and evaluate the validity of blood zinc protoporphyrin as the screening test and blood lead as gold standard of diagnostic test. The total of 2245 lead workers (male workers: 1982, female workers : 263) from 12 lead using industries were studied. Blood lead, ZPP, hemoglobin and hematocrit were selected as lead exposure variables. Personal information on sex, age and work duration were also checked. Blood lead was measured with flameless atomic absorption spectrometry (model: Hitachi 8100) using standard addition method. Blood ZPP was measured with portable hematoflurometer (model: Aviv 206). The results obtained were as follows: 1. The mean blood lead of all lead workers were 0.7±14.3㎍/㎗(Male: 31.0±14.4㎍/㎗, Female: 28.2±12.9㎍/㎗), whereas the mean blood ZPP of those were 68.1±47.5㎍/㎗(Male: 63.9±43.7㎍/㎗, Female: 100.1±61.0㎍/㎗). The mean value of hemoglobin and hematocrit of all lead workers were 14.5±1.5g/㎗(Male: 14.7±1.3g/㎗, Female: 12.3±1.2g/㎗) and 45.4±3.6(Male: 46.2±2.8, Female: 39.5±3.1) respectively. 2. Validity of test using blood zinc protoporphyrin as screening test for blood lead levels of 30㎍/㎗ as gold standard of diagnostic test revealed that the highest validity value for male and female lead workers were 50 and 90 ㎍/㎗ of ZPP respectively, showing 50 and 60 ㎍/㎗ of ZPP for all lead workers. While those test for blood lead levels of 40㎍/㎗ as gold standard of diagnostic test revealed that the highest validity value for male and female lead workers were 60 and 90 ㎍/㎗ of ZPP respectively, showing 60 ㎍/㎗ of ZPP for all lead workers, those test for blood lead levels of 50 and 60㎍/㎗ as gold standard of diagnostic test revealed that the highest validity value for male and female lead workers were 60 or 70 and 100 ㎍/㎗ ZPP respectively, showing 60and 70 or 80 ㎍/㎗ of ZPP for all lead workers. 3. Predictive value of test using blood zinc protoporphyrin as the screening test for different blood lead levels of 30, 40, 50 and 60㎍/㎗ as gold standard of diagnostic test revealed that positive predictive value of screening test were decreased by the increase of blood lead level regardless of csreening criteria value ZPP and negative predictive value of screening test were increased accordingly regardless of screening criteria value of ZPP. On the other hand, within same blood lead level as a gold standard positive predictive values were inceased by the increase of screening criteria value of ZPP, whereas the negative predictive value were decreased accordingly by the the increase of screening criteria value of ZPP. 4. The correlation analysis of all lead workers among study variables revealed that CPbB and natural log transformation ZPP(LZPP) were better correlated with other variables and found to be better estimate than PbB and ZPP themselves. The age was correlated with all other variables, but the work duration was not. The correlation analysis of male and female workers among study variables revealed the same results with all lead workers. 5. The slope of simple linear regression of CPbB (independent variable) with ZPP in female workers(3.223)was steeper than in male workers(2.144). That of lead workers with work duration of less than 1 year was steeper than that of lead workers whose work duration was more than 1 year. But there was no slope difference between two groups divided by their work duration of 2 years less and more. The slope of simple linear regression of CPbB lead (independent variable)with ZPP in lead workers whose blood lead were higher than 30㎍/㎗and 40㎍/㎗ were steeper than those whose blood lead were less than 30㎍/㎗ and 40㎍/㎗. 6. The slope of simple linear regression of CPbB (independent variable) with ZPP in lead industries with low mean blood lead were less steeper than those with high mean blood lead. 7. The slope of simple linear regression of CPbB (independent variable) with LZPP in female workers(0.0308was steeper than in male workers(0.0253). That of lead workers with work duration of less than 1 year was steeper than that of lead workers whose work duration was more than 1 year. But where was no slope difference between two groups divided by their work duration of 2 years less and more. While the slope of simple linear regression of CPbB lead (independent variable) with LZPP in lead workers whose blood lead were hogher than 30㎍/㎗ was not steeper than those whose blood lead were less than 30㎍/㎗, there was no slope difference between two groups whose blood lead were less than 40㎍/㎗ and more than 40㎍/㎗. 8. The slope of simple linear regression of CPbB (independent variable) with LZPP in lead industries with low mean blood lead were less steeper than those with high mean blood lead, but the difference was not significant then that of CPbB and ZPP. With above results, it is recommended that the screening criteria value of ZPP should be down to 60-70㎍/㎗ from 100㎍/㎗ for male lead workers and screening criteria of ZPP for female lead workers was all right with current value of 100㎍/㎗. So it is recommended to make different screening criteria of ZPP for male and female workers like the hemoglobin and hematocrit screening criteria. It is also preferable to use CPbB and LZPP rather than uncorrected PbB and ZPP in the evaluation of lead exposure for lead workers.

Collective Motion of Conducting Filaments in Pt/n-Type TiO2/p-Type NiO/Pt Stacked Resistance Switching Memory

Kim, K. M.,Song, S. J.,Kim, G. H.,Seok, J. Y.,Lee, M. H.,Yoon, J. H.,Park, J.,Hwang, C. S. John Wiley Sons, Ltd 2011 Advanced Functional Materials Vol.21 No.9

Evolution of the shape of the conducting channel in complementary resistive switching transition metal oxides

Yoon, K.,Song, S.,Seok, J.,Yoon, J.,Park, T.,Kwon, D.,Hwang, C. Royal Society of Chemistry 2014 Nanoscale Vol.6 No.4

Ultimate control of the defect distribution and local conduction path in a bipolar resistive switching (BRS) Pt/TiO2/Pt sample, which was in a unipolar reset state, is provided by means of voltage pulsing and the resulting time-transient current analysis. The limited amount of oxygen vacancies in this system allowed reversibly switching-diode-like current-voltage curves, which was also confirmed in another Magneli-phase-containing Pt/WO3/Pt sample. Such careful control of the defect distribution allowed the achievement of a complementary resistive switching (CRS) curve even from a single switching layer. The unlimited vacancy source in the Pt/TiO2/TiO2-x/Pt sample did not allow the switching-diode type and the CRS behavior. The data retention of the on-state in the BRS was critically dependent on the shape of the rejuvenated conduction channel. The required time to lead to the rejuvenation of the conducting channel was similar to 70-100 ns when the threshold voltage for the BRS set of similar to-1 V was applied.

수도용 생력제형 500g 입제의 확산성과 잡초방제 효과

김경현(K. H. Kim),이계환(K. H. Lee),석창수(C. S. Seok),김현재(H. J. Kim),윤철수(C. S. Yoon),황인천(I. C. Hwang) 한국잡초학회 2009 한국잡초학회 별책(학술대회 초록집) Vol.29 No.2