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Shape reformable polymeric nanofibers entrapped with QDs as a scaffold for enzyme stabilization
Hwang, Ee Taek,Tatavarty, Rameshwar,Lee, Hyun,Kim, Jungbae,Gu, Man Bock Royal Society of Chemistry 2011 Journal of materials chemistry Vol.21 No.14
<P>In this study, we report the structure and shape of new polymeric nanofibers entrapped with QDs, which were prepared by electrospinning a homogenous mixture of polymers and QDs. Uniformly distributed QDs within the polymer matrix seem to induce the high degree of compactness and shape rigidity in the nanofibers, and resulted in the efficient enzyme immobilization. After immobilization, the esterase enzymes coated on the QDs–nanofibers showed good stability with no loss of enzyme activity even after being recycled for more than ten times. The present study demonstrates the successful application of shape reformable polymeric nanofibers entrapped with QDs for enzyme immobilization for the first time, and so it is anticipated that this technology can be employed in various enzyme applications due to its facile shape control feature in the fabrication of the nanofibers.</P> <P>Graphic Abstract</P><P>QDs entrapped shape reformable polymeric nanofibres as a novel carrier for enzyme stabilization. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c0jm02969f'> </P>
Hwang, Ee Taek,Lee, Byoungsoo,Zhang, Meiling,Jun, Seung-Hyun,Shim, Jongmin,Lee, Jinwoo,Kim, Jungbae,Gu, Man Bock The Royal Society of Chemistry 2012 GREEN CHEMISTRY Vol.14 No.7
<P>Subtilisin Carlsberg (SC) was immobilized and stabilized on magnetically-separable mesoporous silica (Mag-MSU-F) in the form of nanoscale enzyme reactors (NERs) based on the ship-in-a-bottle mechanism. Stabilized NERs of SC (NER-SC) were freeze-dried and successfully used for the transesterification of <I>N</I>-acetyl-<SMALL>L</SMALL>-phenylalanine ethyl ester with <I>n</I>-propanol in isooctane. Magnetic separation of Mag-MSU-F facilitated the repeated usages of stable NER-SC. This is the first demonstration for the use of stable and magnetically-separable NERs in an organic solvent, which has the potential for environmentally-friendly synthesis using enzymes in organic solvents.</P> <P>Graphic Abstract</P><P>Highly-stable and magnetically-separable nanoscale enzyme reactors for enzyme-catalyzed synthetic reactions. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2gc35559k'> </P>
Systematic Reliability Study of Top-Gate p- and n-Channel Organic Field-Effect Transistors
Hwang, Do Kyung,Fuentes-Hernandez, Canek,Fenoll, Mathieu,Yun, Minseong,Park, Jihoon,Shim, Jae Won,Knauer, Keith A.,Dindar, Amir,Kim, Hyungchul,Kim, Yongjin,Kim, Jungbae,Cheun, Hyeunseok,Payne, Marcia American Chemical Society 2014 ACS APPLIED MATERIALS & INTERFACES Vol.6 No.5
<P>We report on a systematic investigation on the performance and stability of p-channel and n-channel top-gate OFETs, with a CYTOP/Al<SUB>2</SUB>O<SUB>3</SUB> bilayer gate dielectric, exposed to controlled dry oxygen and humid atmospheres. Despite the severe conditions of environmental exposure, p-channel and n-channel top-gate OFETs show only minor changes of their performance parameters without undergoing irreversible damage. When correlated with the conditions of environmental exposure, these changes provide new insight into the possible physical mechanisms in the presence of oxygen and water. Photoexcited charge collection spectroscopy experiments provided further evidence of oxygen and water effects on OFETs. Top-gate OFETs also display outstanding durability, even when exposed to oxygen plasma and subsequent immersion in water or operated under aqueous media. These remarkable properties arise as a consequence of the use of relatively air stable organic semiconductors and proper engineering of the OFET structure.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2014/aamick.2014.6.issue-5/am405424k/production/images/medium/am-2013-05424k_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am405424k'>ACS Electronic Supporting Info</A></P>
Interactive CO2 Adsorption on the BaO (100) Surface: A Density Functional Theory (DFT) Study
권순철,JungBae Hwang,이한림,이왕로 대한화학회 2010 Bulletin of the Korean Chemical Society Vol.31 No.8
A density functional theory (DFT) study of CO2 adsorption on barium oxide (BaO) adsorbents is conducted to understand the chemical activity of the oxygen site on the BaO (100) surface. This study evaluated the adsorption energies and geometries of a single CO2 molecule and a pair of CO2 molecules on the BaO (100) surface. A quantum calculation was performed to obtain information on the molecular structures and molecular reaction mechanisms; the results of the calculation indicated that CO2 was adsorbed on BaO to form a stable surface carbonate with strong chemisorption. To study the interactive CO2 adsorption on the BaO (100) surface, a pair of CO2 molecules was bound to neighboring and distant oxygen sites. The interactive CO2 adsorption on the BaO surface was found to slightly weaken the adsorption energy, owing to the interaction between CO2 molecules.
Oh, Jungbae,Jo, Sung-Hoon,Kim, Justin S.,Ha, Kyoung-Soo,Lee, Jung-Yun,Choi, Hwang-Yong,Yu, Seok-Yeong,Kwon, Young-In,Kim, Young-Cheul MDPI 2015 INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES Vol.16 No.4
<P>Type 2 diabetes mellitus (T2DM) is a metabolic disorder characterized by postprandial hyperglycemia, which is an early defect of T2DM and thus a primary target for anti-diabetic drugs. A therapeutic approach is to inhibit intestinal α-glucosidase, the key enzyme for dietary carbohydrate digestion, resulting in delayed rate of glucose absorption. Although tea extracts have been reported to have anti-diabetic effects, the potential bioactivity of tea pomace, the main bio waste of tea beverage processing, is largely unknown. We evaluated the anti-diabetic effects of three selected tea water extracts (TWE) and tea pomace extracts (TPE) by determining the relative potency of extracts on rat intestinal α-glucosidase activity <I>in vitro</I> as well as hypoglycemic effects <I>in vivo</I>. Green, oolong, and black tea bags were extracted in hot water and the remaining tea pomace were dried and further extracted in 70% ethanol. The extracts were determined for intestinal rat α-glucosidases activity, radical scavenging activity, and total phenolic content. The postprandial glucose-lowering effects of TWE and TPE of green and black tea were assessed in male Sprague-Dawley (SD) rats and compared to acarbose, a known pharmacological α-glucosidase inhibitor. The IC<SUB>50</SUB> values of all three tea extracts against mammalian α-glucosidase were lower or similar in TPE groups than those of TWE groups. TWE and TPE of green tea exhibited the highest inhibitory effects against α-glucosidase activity with the IC<SUB>50</SUB> of 2.04 ± 0.31 and 1.95 ± 0.37 mg/mL respectively. Among the specific enzymes tested, the IC<SUB>50</SUB> values for TWE (0.16 ± 0.01 mg/mL) and TPE (0.13 ± 0.01 mg/mL) of green tea against sucrase activity were the lowest compared to those on maltase and glucoamylase activities. In the animal study, the blood glucose level at 30 min after oral intake (0.5 g/kg body wt) of TPE and TWE of both green and black tea was significantly reduced compared to the control in sucrose-loaded SD rats. The TPE of all three teas had significantly higher phenolic content than those of the TWE groups, which correlated strongly with the DPPH radical scavenging activity. This is the first report of tea pomace extract significantly inhibits intestinal α-glucosidase, resulting in delayed glucose absorption and thereby suppressed postprandial hyperglycemia. Our data suggest that tea pomace-derived bioactives may have great potential for further development as nutraceutical products and the reuse of otherwise biowaste as valuable bioresources for the industry.</P>
Lee, Hanlim,Hwang, JungBae,Son, Yoonhee The Korean Society of Remote Sensing 2013 大韓遠隔探査學會誌 Vol.29 No.3
This present study describes an application of UV scanning spectrometer $O_4$ data for retrieval of aerosol vertical profiles in Seoul during the measurement period that includes two Asian dust event days. The results show large variations of aerosol load in vertical and temporal scales. Large variations in aerosol were observed at 1 km in height during the daytime in the measurement period when the Asian dust events took place. The aerosol load, however, was found to be largest at the surface compared to those retrieved at the higher atmospheric layers. The results also clearly identified the diurnal patterns of aerosol vertical distributions. The aerosol load was high in the morning and noon whereas it was low in the afternoon. This study demonstrates that UV scanning spectrometer observations of the oxygen dimer can serve as a potential method for determination of atmospheric aerosol vertical distributions and optical properties.
Eum, Ji Young,Hwang, Sang Youn,Ju, Youngjun,Shim, Jong Min,Piao, Yunxian,Lee, Jinwoo,Kim, Hak-Sung,Kim, Jungbae The Royal Society of Chemistry 2014 Chemical communications Vol.50 No.27
<P>A highly sensitive immunoassay was developed by using antibody-conjugated spherical mesoporous silica with immobilized enzymes. The higher ratio of enzyme/antibody than conventional ELISA improved both the sensitivity and dynamic range. Especially, the use of spherical mesoporous silica could achieve a limit of detection (LOD) with a sensitivity that is 20 times more than that of ELISA using amorphous silica.</P> <P>Graphic Abstract</P><P>A highly sensitive immunoassay was developed by using antibody-conjugated spherical mesoporous silica with immobilized enzymes. High ratio of enzyme to antibody improved both the sensitivity and dynamic range. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c3cc48044e'> </P>
이한림,노영민,류재영,JungBae Hwang,원용관 한국광학회 2011 Current Optics and Photonics Vol.15 No.1
Simultaneous measurements using a scanning spectrograph system and transmissometer were performed for the first time over an urban site in Gwangju, Korea, to derive the ambient NO_2 volume mixing ratio. The differential slant column densities retrieved from the scanning spectrograph system were converted to volume mixing ratios using the light traveling distance along the scanning line of sight derived from the transmissometer light extinction coefficients. To assess the performance of this system, we compared the derived NO_2 volume mixing ratios with those measured by an in situ chemiluminescence monitor under various atmospheric conditions. For a cloudless atmosphere, the linear correlation coefficient (R) between the two data sets (i.e., data derived from the scanning spectrograph and from the in situ monitor) was 0.81; the value for a cloudy atmosphere was 0.69. The two sets of NO_2 volume mixing ratios were also compared for various wind speeds. We also consider the measurement errors, as estimated from an error propagation analysis.