Identification and quantification of seven volatile n-nitrosamines in cosmetics using gas chromatography/chemical ionization-mass spectrometry coupled with head space-solid phase microextraction

Choi, N.R.,Kim, Y.P.,Ji, W.H.,Hwang, G.S.,Ahn, Y.G. Pergamon Press ; Elsevier Science Ltd 2016 Talanta Vol.148 No.-

<P>An analytical method was developed for the identification and quantification of seven volatile n-nitrosamines (n-nitrosodimethylamine [NDMA], n-nitrosoethylmethylamine [NMEA], n-nitrosodiethylamine [NDEA], n-nitrosodipropylamine [NDPA], n-nitrosodibutylamine [NDBA], n-nitrosopiperidine [NPIP], and n-nitrosopyrrolidine [NPYRD]) in water insoluble cream type cosmetics. It was found that the head space-solid phase microextraction (HS-SPME) was suitable for extraction, clean up, and pre-concentration of n-nitrosamines in the cream type samples so its optimal conditions were investigated. Identification and quantification of n-nitrosamines using single quadrupole gas chromatography/mass spectrometry (GC/MS) in chemical ionization (CI) mode were carried out with accurate mass measurements. Their accurate masses of protonated molecular ions were obtained within 10 mDa of the theoretical masses when sufficiently high signal was acquired from the unique calibration method using mass and isotope accuracy. For the method validation of quantification, spiking experiments were carried out to determine the linearity, recovery, and method detection limit (MDL) using three deuterated internal standards. The average recovery was 79% within 20% relative standard deviation (RSD) at the concentration of 50 ng/g. MDLs ranged from 0.46 ng/g to 36.54 ng/g, which was satisfactory for the directive limit of 50 ng/g proposed by the European Commission (EC). As a result, it was concluded that the method could be provided for the accurate mass screening, confirmation, and quantification of n-nitrosamines when applied to cosmetic inspection. (C) 2015 Elsevier B.V. All rights reserved.</P>

Microstructural, chemical states and electrical properties of Au/CuO/n-InP heterojunction with a cupric oxide interlayer

Balaram, N.,Rajagopal Reddy, V.,Sekhar Reddy, P.R.,Janardhanam, V.,Choi, Chel-Jong Elsevier 2018 Vacuum Vol.152 No.-

<P><B>Abstract</B></P> <P>Cupric oxide (CuO) is synthesized by simple chemical bath deposition method and deposited on n-type InP substrate using e-beam evaporation technique. First, the structural and chemical compositional analysis of CuO/n-InP are analysed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). XRD and XPS results confirmed that the formation of CuO on n-type InP substrate. Then, Au/CuO/n-InP heterojunction is fabricated with a CuO interlayer and correlated its results with the Au/n-InP Schottky junction (SJ). The barrier height (Φ<SUB>b</SUB>) and ideality factor (n) are extracted through I-V and C-V methods and the respective values are 0.66 eV (I-V)/0.80 eV (C-V) and 1.24, and 0.78 eV (I-V)/0.94 eV (C-V) and 1.62 for the SJ and HJ diodes, respectively. By applying Cheung's and Norde functions, the Φ<SUB>b</SUB>, ideality factor and series resistance (R<SUB>S</SUB>) are derived for the SJ and HJ diodes. The derived interface state density (N<SUB>SS</SUB>) of HJ is lower than the SJ; results demonstrated that the CuO interlayer plays an important role in the decreased N<SUB>SS</SUB>. The Poole-Frenkel emission is the dominant current conduction mechanism in reverse bias of both SJ and HJ diodes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Structural and chemical properties of CuO films are analysed by XRD and XPS. </LI> <LI> Barrier height of Au/n-InP SJ was modified by CuO interlayer. </LI> <LI> Heterojunction has a good rectification ratio compared to the Schottky junction. </LI> <LI> The interface state density of HJ is lower as compared to the SJ. </LI> <LI> Poole-Frenkel mechanism is found to dominate in both SJ and HJs. </LI> </UL> </P>

Effects of the novel angiotensin II receptor type I antagonist, fimasartan on myocardial ischemia/reperfusion injury

Han, J.,Park, S.J.,Thu, V.T.,Lee, S.R.,Long, L.T.,Kim, H.K.,Kim, N.,Park, S.W.,Jeon, E.S.,Kim, E.J.,Yoon, C.H.,Cho, G.Y.,Choi, D.J. Elsevier/North-Holland Biomedical Press 2013 INTERNATIONAL JOURNAL OF CARDIOLOGY Vol.168 No.3

Background: The aim of this study was to investigate the cardioprotective effect of fimasartan, a newly developed angiotensin II receptor type I blocker (ARB), against myocardial ischemia/reperfusion (I/R) injury and to identify the mechanism by which it reduces mitochondrial damage. Methods: Fimasartan was administered intravenously to Sprague-Dawley rats (3mg/kg), cardiomyocytes (50μM), and H9c2 cells (50μM) before ischemia or hypoxia. Myocardial infarction (MI), echocardiograms, DNA fragmentation, terminal deoxynucleotidyl transferase-mediated dUTP in situ nick-end labeling, immunoblotting, oxygen consumption, confocal microscopic appearance, and L-type Ca<SUP>2+</SUP> current (I<SUB>Ca,L</SUB>) were then assessed. Results: Fimasartan pretreatment remarkably reduced the rate of MI and improved cardiac performance well after I/R (n=9/group). Fimasartan also reduced apoptotic cell death both in vivo and in hypoxia/reoxygenation (H/R)-treated H9c2 cells (n=5~8/group). H/R-induced mitochondrial O<SUB>2</SUB><SUP>-</SUP> production and collapse of membrane potential were markedly attenuated in fimasartan-treated cardiomyocytes (n=4~6/group). Additionally, mitochondrial Ca<SUP>2+</SUP> overload during reoxygenation was suppressed by fimasartan (n=4~6/group), and this was found to be possibly related to the inhibition of I<SUB>Ca,L</SUB> and mitochondrial Ca<SUP>2+</SUP> uniporter. Furthermore, fimasartan pretreatment increased phosphorylations of Akt and glycogen synthase kinase-3β (n=5~7/group), decreased pro-apoptotic p53 levels, and increased anti-apoptotic Bcl-2 levels (n=4) during reperfusion. Conclusions: Fimasartan preconditioning has the potential to modulate Bcl-2 and suppress I/R-induced Ca<SUP>2+</SUP> overload by inhibiting I<SUB>Ca,L</SUB> and MCU. These beneficial effects could prevent the mitochondrial dysfunction and apoptosis accompanied by I/R.

임신기간중 혈장 Fibronectin 농도변화를 이용한 임신성 고혈압 발생의 예측 가능성에 관한 연구

정두용,최종현,최경남,김민철,승경록 건국대학교 의과학연구소 1995 건국의과학학술지 Vol.5 No.-

Preeclampsia is classically defined as the triad of pregnancy induced hypertension(PIH) with generalized edema and proteinuria, and constitutes a deadly triad of maternal death. Recent studies suggest that drugs affecting prostacyclin and thromboxane production may be able to affect the development of preeclampsia(PE). In order to use these agents effectively, a woman at high risk should be selected properly before the clinical illness manifests. As the pathophysiologic mechanism of PE., endothelial damage is thought to play a major role in these days. Many investigators have suggested that plasma fibronectin(FN), a good indicator of vascular endothelial damage, is markedly elevated at least 4 weeks before clinical manifestations of PE and can be used as a sensitive predictor of PIH. To assess the clinical utility of plasma FN in predicting PIH, plasma FN concentrations of pregnant women over 28 weeks of gestation who visited Kon-Kuk University Hospital from June 1, 1994 to February 28, 1995 were assayed. The results were as follows: among 108 pregnancy specimens, 70 were in the normal blood pressure group and 38 were PIH group: 20, transient hypertension subgroup(PH), 8, mild PE subgroup(PM), 10, severe PE subgroup(PS). There was statistical significance in the mean birthweight between normal blood pressure group(3,205±68g) and PS subgroup(2,455±315g) (p<0.05). The mean concentrations of plasma FN were highest in the PS subgroup(412±68.9ug/㎖) and lowest in the normal blood pressure group(244±8.7ug/㎖), that is stastically significant. Plasma FN concentration in the normal pregnancy period showed fluctuation: from 29 weeks of gestation to 36 weeks, elevation and after 36 weeks, decline. The changes in the mean concentrations of plasma FN after delivery were noted in both groups, but those in normal blood pressure group(254±13→227±10㎍/㎖) and PS(405±22→318±51㎍/㎖)were stastically significant(p<0.05). There was negative linear correlation between the platelet count and concentration of plasma FN in the PS group [platelets(Y)=-0.20192×FN(X)+262.23257 r=0.69] (p<0.05). There was no linear correlation between the birthweight and plasma FN concentration in normal blood pressure group and PIH group. The changes in the plasma FN concentration in the normal blood pressure group and PIH group before clinical manifestation were not statistically significant.

Speciation and source identification of organic compounds in PM₁₀ over Seoul, South Korea

Choi, N.R.,Lee, S.P.,Lee, J.Y.,Jung, C.H.,Kim, Y.P. Pergamon Press 2016 CHEMOSPHERE - Vol.144 No.-

Seventy three individual organic compounds in the atmospheric particulate matter with an aerodynamic diameter of less than or equal to a nominal 10 μm (PM<SUB>10</SUB>) over Seoul were identified and quantified from April 2010 to April 2011 using gas chromatography/mass spectrometry (GC/MS). These organic compounds were classified into five groups, n-alkanes, polycyclic aromatic hydrocarbons (PAHs), mono-carboxylic acids, di-carboxylic acids (DCAs), and sugars based on their chemical structures and properties. The organic compounds showed higher seasonal average concentrations from fall to winter than from spring to summer due to source strength, except some organic compounds among mono-carboxylic acids, DCAs, sugars such as undecanoic acid, methylmalonic acid, and fructose. Through qualitative data analysis using seasonal concentration variations and relevant diagnostic parameters, it was found that (1) anthropogenic sources such as combustion of fossil fuel and biomass burning attributed more to the formation of the organic aerosols than biogenic sources, and (2) the ambient level of n-alkanes, PAHs, and some compounds of DCAs and sugars was elevated in winter due to the increased primary emissions and larger transport from outside of the organic compounds in winter.

기계시각을 이용한 장미와 국화 절화의 품질 계측장치 개발

최승묵,서상룡,조남홍,박종률 한국농업기계학회 2003 바이오시스템공학 Vol.28 No.3

Rose and chrysanthemum are the most popular flowers in Korean floriculture. Sorting flowers is a labor intensive operation in cultivation of the cut flowers and needed to be mechanized. Machine vision is one of the promising solutions for this purpose. This study was carried out to develop hardware and software of a cut flower sorting system using machine vision and to test its performance. Results of this study were summarized as following; 1.Length of the cut flower measured by the machine vision system a good correlation with actual length of the flower at a level of the coefficients of determination(R^2) of 0.9948 and 0.9993 for rose and chrysanthemum respectively and average measurement errors of the system were about 2% and 1% of the shortest length of the sample flowers. The experimental result showed that the machine vision system could be used successfully to measure length of the cut flowers. 2.Stem diameter of the cut flowers measures by the machine vision system showed a correlation with actual diameter at the coefficients of determination(R^2) of 0.8429 and 0.9380 for rose and chrysanthemum respectively and average measurement errors of the system were about 15% and 7.5% of the shortest diameter of the sample flowers which could be a serious source of error in grading operation. It was recommended that the error rate should be considered to set up grading conditions of each class of the cut flowers. 3.Bud maturity of 20 flowers each judged using the machine vision system a coincidence with the judgement by inspectors at ranges of 80%~85% and 85%~90% for rose and chrysanthemum respectively. Performance of the machine vision system to judge bud maturity could be improved through setting up more precise criteria to judge the maturity with more samples of the flowers. 4.Quality of flower judged by stem curvature using the machine vision system showed a coincidence with the judgement by inspectors at 90% for good and 85% for bad flowers of both rose and chrysanthemum. The levels of coincidence was considered as that the machine vision system used was an acceptable system to judge the quality of flower by stem curvature.

Highly active and durable nitrogen doped-reduced graphene oxide/double perovskite bifunctional hybrid catalysts

Kim, N. I.,Afzal, R.,Choi, S.,Lee, S.,Ahn, D.,Bhattacharjee, S.,Lee, S. C.,Kim, J.,Park, J. Y. Royal Society of Chemistry 2017 Journal of materials chemistry. A, Materials for e Vol.5 No.25

<P>A-site cation doping in perovskite-based materials with the general ABO(3) formula has a significant effect on the bifunctional oxygen activity (oxygen evolution and reduction reactions) of chemically stable electrocatalysts, enabling the design of highly active, durable, and cost-effective catalysts. In particular, the oxygen activity of double perovskite-structured NdBa0.5Sr0.5Co1.5Fe0.5O5+delta (NBSCF) is 0.973 V, which is much greater than that of previously reported transition metal-based nanostructures. This result is verified by examination of the electronic structure, oxidation state, and electrical properties of the perovskite-based materials using density functional theory (DFT) calculations, the iodometric titration method, X-ray photon spectroscopy (XPS), and electrochemical impedance spectroscopy (EIS) analysis. Further improvements of NBSCF for bifunctional oxygen activity are made by incorporating these synergistic hybrid structures with nitrogen doped-reduced graphene-based (N-rGO) nanostructures (NBSCF/N-rGO). The NBSCF/N-rGO has an oxygen electrode activity of 0.766 V, which is superior to that of other previously reported transition metal-based nanostructures and compares favorably to that of precious metal electrocatalysts. Furthermore, strong N-rGO provides considerably greater electrochemical long-term stability and integrity to NBSCF/N-rGO hybrid catalysts under continuous chronopotentiometric and long-term potential sweep testing conditions for the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR).</P>

MOA-2010-BLG-073L: AN M-DWARF WITH A SUBSTELLAR COMPANION AT THE PLANET/BROWN DWARF BOUNDARY

Street, R. A.,Choi, J.-Y.,Tsapras, Y.,Han, C.,Furusawa, K.,Hundertmark, M.,Gould, A.,Sumi, T.,Bond, I. A.,Wouters, D.,Zellem, R.,Udalski, A.,Snodgrass, C.,Horne, K.,Dominik, M.,Browne, P.,Kains, N.,Br IOP Publishing 2013 The Astrophysical journal Vol.763 No.1

<P>We present an analysis of the anomalous microlensing event, MOA-2010-BLG-073, announced by the Microlensing Observations in Astrophysics survey on 2010 March 18. This event was remarkable because the source was previously known to be photometrically variable. Analyzing the pre-event source light curve, we demonstrate that it is an irregular variable over timescales >200 days. Its dereddened color, (V - I)(S),(0), is 1.221 +/- 0.051 mag, and from our lens model we derive a source radius of 14.7 +/- 1.3 R-circle dot, suggesting that it is a red giant star. We initially explored a number of purely microlensing models for the event but found a residual gradient in the data taken prior to and after the event. This is likely to be due to the variability of the source rather than part of the lensing event, so we incorporated a slope parameter in our model in order to derive the true parameters of the lensing system. We find that the lensing system has a mass ratio of q = 0.0654 +/- 0.0006. The Einstein crossing time of the event, t(E) = 44.3 +/- 0.1 days, was sufficiently long that the light curve exhibited parallax effects. In addition, the source trajectory relative to the large caustic structure allowed the orbital motion of the lens system to be detected. Combining the parallax with the Einstein radius, we were able to derive the distance to the lens, D-L = 2.8 +/- 0.4 kpc, and the masses of the lensing objects. The primary of the lens is an M-dwarf with M-L,M-1 = 0.16 +/- 0.03 M-circle dot, while the companion has M-L,M-2 = 11.0 +/- 2.0 M-J, putting it in the boundary zone between planets and brown dwarfs.</P>

Phase I/II study of S-1 combined with weekly docetaxel in patients with metastatic gastric carcinoma

Park, S R,Kim, H K,Kim, C G,Choi, I J,Lee, J S,Lee, J H,Ryu, K W,Kim, Y-W,Bae, J-M,Kim, N K Cancer Research UK 2008 The British journal of cancer Vol.98 No.8

We designed a phase I/II trial of S-1 combined with weekly docetaxel to determine the maximum tolerated dose (MTD) and recommended dose (RD) and to evaluate the efficacy and toxicity in metastatic gastric carcinoma (MGC). Patients with measurable disease received S-1 orally b.i.d. on days 1–14 and docetaxel intravenously on days 1 and 8 every 3 weeks. In phase I (n=30), each cohort received escalating doses of S-1 (30–45 mg m<SUP>−2</SUP> b.i.d.) and docetaxel (25–40 mg m<SUP>−2</SUP>); MTD was 45 mg m<SUP>−2</SUP> b.i.d. S-1/35 mg m<SUP>−2</SUP> docetaxel and RD was 40 mg m<SUP>−2</SUP> b.i.d. S-1/35 mg m<SUP>−2</SUP> docetaxel. Dose-limiting toxicities included grade 3 elevated liver enzymes, gastric perforation, grade 3 diarrhoea/fatigue, febrile neutropenia with grade 3 anorexia/fatigue, and neutropenic infection with grade 3 stomatitis/anorexia. In phase II (n=52), the overall response rate was 66.7% (95% confidence interval (CI): 53.8–79.6%) and the median time to progression and overall survival were 6.5 months (95% CI: 4.9–8.1) and 13.7 months (95% CI: 9.9–17.5), respectively. The most common grade 3/4 toxicity was neutropenia (29.4%), and febrile neutropenia/neutropenic infection occurred in 19.6% of patients. Non-haematological toxicities were generally mild. There was one treatment-related death due to pneumonitis. S-1 combined with weekly docetaxel is active in MGC with moderate toxicities.British Journal of Cancer (2008) 98, 1305–1311. doi:10.1038/sj.bjc.6604312 www.bjcancer.com Published online 25 March 2008

Effect of oxygen plasma treatment on the electrical characteristics of Pt/n-type Si Schottky diodes

Janardhanam, V.,Jyothi, I.,Yuk, S. H.,Choi, C. J.,Lee, S. N.,Reddy, V. R. 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol. No.

<P>The electrical properties of Pt/n-type Si Schottky diodes fabricated from n-type Si wafers subjected to an oxygen (O-2) plasma treatment were investigated as a function of the power of the O-2 plasma. The Pt/n-type Si Schottky diode with an O-2 plasma treatment at a power of 100 W showed better rectifying characteristics with increasing barrier height and decreasing ideality factor compared to the conventional Pt/n-type Si Schottky diodes. This could be attributed to an improvement in the interface homogeneity associated with damage-free surface smoothing driven by the O-2 plasma treatment at a power of 100 W. On the other hand, with increasing power of the O-2 plasma for powers above 150 W, the barrier height decreased and the leakage current increased, indicating degradation of the device performance. The degradation in the rectifying properties after the O-2 plasma treatment at a higher plasma power in excess of 150 W could be associated with increases in the series resistance and the interface state density caused by plasma-induced damage to the Si surface.</P>