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( Sehun Kim ),( Donghoon Han ),( Jae Hyuk Choi ),( Eun-joo Park ),( Dong Geum Shin ),( Min-kyung Kang ),( Seonghoon Choi ),( Namho Lee ),( Jung Rae Cho ) 대한내과학회 2021 The Korean Journal of Internal Medicine Vol.36 No.0
Background/Aims: Prolonged dual antiplatelet therapy (DAPT) with aspirin and clopidogrel beyond 1 year has been shown to reduce ischemic events at the expense of increased bleeding. However, limited data are available on the clinical significance of platelet reactivity (PR) at 1 year. Methods: We retrospectively identified 331 patients who underwent percutaneous coronary intervention (PCI) and assessed the on-clopidogrel PR using VerifyNow P2Y12 assay at 1 year in a single center. Two hundred eleven patients were on DAPT for > 1 year. The relationship between high on-treatment platelet reactivity (HPR) at 1 year and clinical outcomes beyond 1 year, as well as the longitudinal change in PR was analyzed. Results: At 1 year, 135 (64%) patients showed HPR and 76 (36%) did not. There was a significant increase in ischemic endpoint events, including cardiovascular death, non-fatal myocardial infarction, and stroke/transient ischemic attack in patients with compared to without HPR at 1 year (hazard ratio [HR], 2.68; 95% confidence interval [CI], 1.06 to 6.77; p = 0.036). However, the incidence of any Bleeding Academic Research Consortium bleeding was significantly lower in the HPR group (HR, 0.11; 95% CI, 0.02 to 0.65; p = 0.015). In the longitudinal analysis, PR significantly decreased from post-load to 1 year after index PCI in the non-HPR group. Conversely, the HPR group showed high PR from baseline through 1 year. Conclusions: HPR at 1 year may be a useful surrogate for predicting ischemic and bleeding events in patients on prolonged DAPT. Patients with and without HPR at 1 year showed different patterns of longitudinal change in PR.
Choi, Sehun,Seo, Han-Seok,Lee, Kwang Rag,Lee, Sunghee,Lee, Junyoung,Lee, Jihyun Elsevier 2019 Food chemistry Vol.276 No.-
<P><B>Abstract</B></P> <P>Although black rice has gained popularity, the changes in volatiles produced during black rice storage remain unclear. Herein, the volatile composition of unmilled and milled black rice stored at 25 °C or 35 °C for 0–12 months was investigated by headspace solid-phase microextraction with gas chromatography–mass spectrometry. Fifty-four volatiles were identified, 15 of which were not previously identified in black rice, including 4-propylbenzaldehyde, methyl 2-hydroxybenzoate, methyl 2-methylpentanoate, 2,5-dimethylnonane, 5-methyldecane, and 2-methylundecane. In this study, octanal increased at a high rate during early storage compared with hexanal, a traditional oxidation marker; thus, octanal may be an early oxidation marker in black rice. The results suggested that high temperature is not appropriate for storage of unmilled or milled black rice because it promotes lipid oxidation, producing volatile compounds. At 25 °C, black rice stored for short times such as 3 months should be milled, whereas for 6 months, black rice should be stored without milling.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The volatiles of black rice stored at 25 °C or 35 °C for 0–12 months was investigated. </LI> <LI> A total of 54 volatiles were identified in fresh and in stored black rice. </LI> <LI> With few exceptions (e.g., guaiacol) most volatiles increased during storage. </LI> <LI> Significant increases were related to the development of lipid oxidation. </LI> </UL> </P>
Choi, Sehun,Seo, Han-Seok,Lee, Kwang Rag,Lee, Sunghee,Lee, Jihyun The Korean Society for Applied Biological Chemistr 2018 Applied Biological Chemistry (Appl Biol Chem) Vol.61 No.1
Six black rice cultivars (Heukjinju, Sintoheugmi, Heukhyangchal 1, Bosukheukchal, Sinnongheukchal, and Josengheukchal) and varying milling degrees (step 0, 0%; step 1, 4.2%; and step 2, 10.5%, w/w) were used to evaluate the effects of cultivars and milling degrees of black rice (Oryza sativa L.) on the total phenolic contents (TPC), total flavonoid contents (TFC), antioxidant activity (2,2-diphenyl-1-picrylhydrazyl free radical assay), and phenolic composition in free and bound phenolic fractions. Unpolished (step 0) Sintoheugmi showed significantly higher TPC, TFC, antioxidant activity, phenolic acid levels, and anthocyanin levels than other unpolished cultivars (p < 0.05). As milling degree increased, TPC, TFC, antioxidant activity, phenolic acid levels, and anthocyanin levels decreased significantly (p < 0.05). TPC, TFC, and antioxidant activity were significantly higher in free phenolic fractions than bound phenolic fractions of black rice extracts, regardless of cultivars (p < 0.05). The major phenolic acid was ferulic acid, and the major anthocyanin found in free phenolic fractions in black rice samples was cyanidin-3-O-glucoside. The sum of individual phenolic acid levels ($255.2{\pm}0.0{\mu}g/g$) and the sum of anthocyanins levels ($831.4{\pm}0.3{\mu}g/g$) were significantly higher in Sintoheugmi black rice than in the other cultivars for step 0 (unpolished rice) (p < 0.05). For step 1 and step 2, Heukjinju black rice contained significantly higher sum of phenolic acid levels and sum of anthocyanin levels than the other cultivars (p < 0.05). For use as a better functional ingredient, it is, therefore, important to consider different milling degrees together with different black rice cultivars having the highest antioxidant component.
Choi, Sehun,Seo, Han-Seok,Lee, Kwang Rag,Lee, Sunghee,Lee, Jihyun The Korean Society for Applied Biological Chemistr 2018 Applied Biological Chemistry (Appl Biol Chem) Vol.61 No.1
Volatile compounds in raw and cooked black rice (cv. Sintoheugmi) samples with different degrees of milling (step 0, 0%; step 1, 4.2%; and step 2, 10.5%, w/w) were investigated by headspace solid-phase microextraction and gas chromatography-mass spectrometry. A total of 101 volatile compounds were found. Among them, 44 compounds found in raw black rice were absent in cooked black rice and 20 compounds were newly formed in cooked black rice. The 8 identified major odor-active volatile compounds in raw and cooked black rice included 3 phenols (guaiacol, 4-vinylphenol, and 2-methoxy-4-vinylphenol), 2 benzenes (benzaldehyde and p-xylene), 2 furans (2-butylfuran and 2-pentylfuran), and 1 terpene (calamenene). Additionally, fatty acid oxidation products such as hexanal, 2-nonenal, octanal, and 2-pentylfuran were found in raw and cooked black rice samples. The relative concentrations of these volatile compounds were significantly higher in step 0 than in step 2 of raw and cooked black rice (p < 0.05). Partially milled cooked black rice (i.e., step 1) contained ~ 80% guaiacol (a favorable unique black rice flavor) of unpolished rice (step 0), with similar levels of several lipid oxidation indicator volatile products (e.g., 2-nonenal and 2-pentyl furan) of fully milled rice (step 2). Thus, partially milled black rice should be consumed rather than fully milled black rice.
Subsurface Incorporation of Co Atoms into Si(100)
Choi, Junghun,Kim, Youngwoo,Lim, Do Kyung,Kim, Do Hwan,Kim, Sehun American Chemical Society 2011 JOURNAL OF PHYSICAL CHEMISTRY C - Vol.115 No.31
<P>The initial adsorption structures of Co on Si(100) were investigated using scanning tunneling microscopy (STM). Filled-state STM images showed bright protrusions at Si dimers. Density functional theory calculations demonstrated that Co atoms at subsurface interstitial sites beneath Si dimers are the most stable. Simulated STM images confirmed that the bright features observed at Si dimers were due to Co atoms incorporated at subsurface interstitial sites.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2011/jpccck.2011.115.issue-31/jp2037872/production/images/medium/jp-2011-037872_0002.gif'></P>
Choi, Hojoong,Seo, Sehun,Lee, Jong-Hoon,Hong, Sang-Hyun,Song, Jaesun,Kim, Seungkyu,Yim, Sang-Youp,Lee, Kwanghee,Park, Seong-Ju,Lee, Sanghan Royal Society of Chemistry 2018 Journal of Materials Chemistry C Vol.6 No.22
<P>UV phototransistors based on ZnO, a material considered promising owing to its wide direct bandgap and high stability in harsh environments, have been intensively investigated. However, ZnO singlelayer UV phototransistors, especially solution-processed devices, still exhibit poor electrical and UV photoresponse characteristics. Herein, we report the fabrication of a low-cost, large-area, and highperformance solution-processed ZnO/SnO2 bilayer UV phototransistor with improved electrical and UV photoresponse characteristics attained by inserting a SnO2 carrier transport layer, which is the actual path of the electrons. The photogenerated electrons are readily transferred from the ZnO UV-sensitive layer to the SnO2 carrier transport layer, owing to the lower conduction band of the SnO2 carrier transport layer than the ZnO UV-sensitive layer. In addition, the efficient extraction of photogenerated electrons from the ZnO UV-sensitive layer through the SnO2 carrier transport layer with high field effect mobility contributes to the improvement in the UV photoresponse characteristics of the ZnO/SnO2 bilayer UV phototransistor. The ZnO/SnO2 bilayer UV phototransistor exhibits high responsivity and detectivity as well as fast photoresponse. These results demonstrate that the solution-processed ZnO/SnO2 bilayer UV phototransistor developed in this study provides a novel approach for improving the performance of UV phototransistors with low-cost and large-area processing.</P>