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201.
Thin-film-based sensitivity enhancement for total internal reflection fluorescence live-cell imaging
We investigated experimentally the evanescent field enhancement based on dielectric thin films in total internal reflection microscopy. The sample employed two layers of Al2O3 and SiO2 deposited on an SF10 glass substrate. Field intensity enhancement measured by fluorescent excitation of microbeads relative to that of a control sample without dielectric films was polarization dependent, determined as 4.2 and 2.4 for TE and TM polarizations, respectively, and was in good agreement with numerical results. The thin-film-based field enhancement was also applied to live-cell imaging of quantum dots, which confirmed the sensitivity enhancement qualitatively. 相似文献
202.
Dong‐Won Lee Won‐Ju Cho Jun‐Kwang Song Oh‐Yun Kwon Won‐Hee Lee Chi‐Hong Park Kyung‐Eun Park Heesoo Lee Yong‐Nam Kim 《Progress in Photovoltaics: Research and Applications》2015,23(7):829-837
High‐temperature‐induced and humidity‐induced degradation behaviors were investigated through the failure analysis of encapsulated Cu(In,Ga)Se2 (CIGS) modules and non‐encapsulated CIGS cells. After being exposed to high temperature (85 °C) for 1000 h, the efficiency loss of CIGS modules and the resistivities of the aluminum‐doped zinc oxide (AZO) layer, CIGS layer, and Mo layer were slightly increased. After damp heat (DH) testing (85 °C/85% RH), the efficiency of some modules decreased significantly accompanied by discoloration, and in these areas, the resistivity of the AZO layers increased markedly. The causes of degradation of CIGS cells after high temperature and DH tests were suggested through X‐ray photoelectron spectroscopy analysis. The high‐temperature‐induced degradation behaviors were revealed to be increases in series resistance of the CIGS cells, due to the adsorption of oxygen on the AZO, CIGS, and Mo layers. The degradation behavior after DH (85 °C/85% RH) exposure was caused by the adsorption of oxygen, as well as the generation of Zn(OH)2 due to water molecules. In particular, the humidity‐induced degradation behavior in discolored CIGS modules was ascribed to the generation of Zn(OH)2 and carboxylic acids in the AZO layer, due to a chemical reaction between the AZO, ethylene‐vinyl acetate copolymer, and water. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
203.
Bongki Cho Hyo Min Cho Hyun Jung Kim Jaehoon Jeong Sang Ki Park Eun Mi Hwang Jae-Yong Park Woon Ryoung Kim Hyun Kim Woong Sun 《Experimental & molecular medicine》2014,46(7):e105
Mitochondrial functions are essential for the survival and function of neurons. Recently, it has been demonstrated that mitochondrial functions are highly associated with mitochondrial morphology, which is dynamically changed by the balance between fusion and fission. Mitochondrial morphology is primarily controlled by the activation of dynamin-related proteins including dynamin-related protein 1 (Drp1), which promotes mitochondrial fission. Drp1 activity is regulated by several post-translational modifications, thereby modifying mitochondrial morphology. Here, we found that phosphorylation of Drp1 at serine 616 (S616) is mediated by cyclin-dependent kinase 5 (CDK5) in post-mitotic rat neurons. Perturbation of CDK5 activity modified the level of Drp1S616 phosphorylation and mitochondrial morphology in neurons. In addition, phosphorylated Drp1S616 preferentially localized as a cytosolic monomer compared with total Drp1. Furthermore, roscovitine, a chemical inhibitor of CDKs, increased oligomerization and mitochondrial translocation of Drp1, suggesting that CDK5-dependent phosphorylation of Drp1 serves to reduce Drp1''s fission-promoting activity. Taken together, we propose that CDK5 has a significant role in the regulation of mitochondrial morphology via inhibitory phosphorylation of Drp1S616 in post-mitotic neurons. 相似文献
204.
Soo Chool Lee Min Sun Cho Suk Yong Jung Chong Kul Ryu Jae Chang Kim 《Adsorption》2014,20(2-3):331-339
A range of potassium-based alumina sorbents were fabricated by impregnation of alumina with K2CO3 to examine the effects of the structural and textural properties of alumina on the CO2 sorption and regeneration properties. Alumina materials, which were used as supports, were prepared by calcining alumina at various temperatures (300, 600, 950, and 1,200 °C). The CO2 sorption and regeneration properties of these sorbents were examined during multiple tests in a fixed-bed reactor in the presence of 1 vol% CO2 and 9 vol% H2O. The regeneration capacities of the potassium-based alumina sorbents increased with increasing calcination temperature of alumina. The formation of KHCO3 increased with increasing calcination temperature during CO2 sorption, whereas the formation of KAl(CO3)(OH)2, which is an inactive material, decreased. These results is due to the fact that the structure of alumina by the calcination temperature is related directly to the formation of the by-product [KAl(CO3)(OH)2]. The structure of alumina plays an important role in enhancing the regeneration capacity of the potassium-based alumina sorbent. Based on these results, a new potassium-based sorbent using δ-Al2O3 as a support was developed for post-combustion CO2 capture. This sorbent maintained a high CO2 capture capacity of 88 mg CO2/g sorbent after two cycles. In particular, it showed a faster sorption rate than the other potassium-based alumina sorbents examined. 相似文献
205.
Simultaneous In Situ Quantification of Two Cellular Lipid Pools Using Orthogonal Fluorescent Sensors 下载免费PDF全文
Dr. Shu‐Lin Liu Dr. Ren Sheng Matthew J. O'Connor Yang Cui Dr. Youngdae Yoon Svetlana Kurilova Dr. Daesung Lee Dr. Wonhwa Cho 《Angewandte Chemie (International ed. in English)》2014,53(52):14387-14391
Lipids regulate a wide range of biological activities. Since their local concentrations are tightly controlled in a spatiotemporally specific manner, the simultaneous quantification of multiple lipids is essential for elucidation of the complex mechanisms of biological regulation. Here, we report a new method for the simultaneous in situ quantification of two lipid pools in mammalian cells using orthogonal fluorescent sensors. The sensors were prepared by incorporating two environmentally sensitive fluorophores with minimal spectral overlap separately into engineered lipid‐binding proteins. Dual ratiometric analysis of imaging data allowed accurate, spatiotemporally resolved quantification of two different lipids on the same leaflet of the plasma membrane or a single lipid on two opposite leaflets of the plasma membrane of live mammalian cells. This new imaging technology should serve as a powerful tool for systems‐level investigation of lipid‐mediated cell signaling and regulation. 相似文献
206.
Transition Metal Chemistry - A facile synthetic approach has been adopted towards the synthesis of (2R,3R)-N2,N3-bis((S)-1-phenylethyl)butane-2,3-diamine via demetalation of its dichloro Zn(II)... 相似文献
207.
208.
Young-Hun Cho Jae-Gyoung Seong Jae-Hyun Noh Da-Young Kim Yong-Sik Chung Tae Hoon Ko Byoung-Suhk Kim 《Molecules (Basel, Switzerland)》2020,25(24)
In this work, we report the carbon fiber-based wire-type asymmetric supercapacitors (ASCs). The highly conductive carbon fibers were prepared by the carbonized and graphitized process using the polyimide (PI) as a carbon fiber precursor. To assemble the ASC device, the CoMnO2-coated and Fe2O3-coated carbon fibers were used as the cathode and the anode materials, respectively. Herein, the nanostructured CoMnO2 were directly deposited onto carbon fibers by a chemical oxidation route without high temperature treatment in presence of ammonium persulfate (APS) as an oxidizing agent. FE-SEM analysis confirmed that the CoMnO2-coated carbon fiber electrode exhibited the porous hierarchical interconnected nanosheet structures, depending on the added amount of APS, and Fe2O3-coated carbon fiber electrode showed a uniform distribution of porous Fe2O3 nanorods over the surface of carbon fibers. The electrochemical properties of the CoMnO2-coated carbon fiber with the concentration of 6 mmol APS presented the enhanced electrochemical activity, probably due to its porous morphologies and good conductivity. Further, to reduce the interfacial contact resistance as well as improve the adhesion between transition metal nanostructures and carbon fibers, the carbon fibers were pre-coated with the Ni layer as a seed layer using an electrochemical deposition method. The fabricated ASC device delivered a specific capacitance of 221 F g−1 at 0.7 A g−1 and good rate capability of 34.8% at 4.9 A g−1. Moreover, the wire-type device displayed the superior energy density of 60.2 Wh kg−1 at a power density of 490 W kg−1 and excellent capacitance retention of 95% up to 3000 charge/discharge cycles. 相似文献
209.
Soumen Dutta Nitee Kumari Sateesh Dubbu Sun Woo Jang Amit Kumar Hiroyoshi Ohtsu Junghoon Kim Seung Hwan Cho Masaki Kawano In Su Lee 《Angewandte Chemie (International ed. in English)》2020,59(9):3416-3422
Rational engineering and assimilation of diverse chemo‐ and biocatalytic functionalities in a single nanostructure is highly desired for efficient multistep chemical reactions but has so far remained elusive. Here, we design and synthesize multimodal catalytic nanoreactors (MCNRs) based on a mesoporous metal‐organic framework (MOF). The MCNRs consist of customizable metal nanocrystals and stably anchored enzymes in the mesopores, as well as coordinatively unsaturated cationic metal MOF nodes, all within a single nanoreactor space. The highly intimate and diverse catalytic mesoporous microenvironments and facile accessibility to the active site in the MCNR enables the cooperative and synergistic participation from different chemo‐ and biocatalytic components. This was shown by one‐pot multistep cascade reactions involving a heterogeneous catalytic nitroaldol reaction followed by a [Pd/lipase]‐catalyzed chemoenzymatic dynamic kinetic resolution to yield optically pure (>99 % ee) nitroalcohol derivatives in quantitative yields. 相似文献
210.
Amit Kumar Nitee Kumari Sateesh Dubbu Sumit Kumar Taewan Kwon Jung Hun Koo Jongwon Lim Inki Kim Yoon‐Kyoung Cho Junsuk Rho In Su Lee 《Angewandte Chemie (International ed. in English)》2020,59(24):9460-9469
Interest and challenges remain in designing and synthesizing catalysts with nature‐like complexity at few‐nm scale to harness unprecedented functionalities by using sustainable solar light. We introduce “nanocatalosomes”—a bio‐inspired bilayer‐vesicular design of nanoreactor with metallic bilayer shell‐in‐shell structure, having numerous controllable confined cavities within few‐nm interlayer space, customizable with different noble metals. The intershell‐confined plasmonically coupled hot‐nanospaces within the few‐nm cavities play a pivotal role in harnessing catalytic effects for various organic transformations, as demonstrated by “acceptorless dehydrogenation”, “Suzuki–Miyaura cross‐coupling” and “alkynyl annulation” affording clean conversions and turnover frequencies (TOFs) at least one order of magnitude higher than state‐of‐the‐art Au‐nanorod‐based plasmonic catalysts. This work paves the way towards next‐generation nanoreactors for chemical transformations with solar energy. 相似文献