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141.
Wonhee Lee Minchul Kwon Seongmin Park Dongwook Lim Dr. Jong‐Ho Cha Prof. Dr. Huen Lee 《化学:亚洲杂志》2013,8(7):1569-1573
Herein, we suggest a new approach to an electric double‐layer capacitor (EDLC) that is based on a proton‐conducting ionic clathrate hydrate (ICH). The ice‐like structures of clathrate hydrates, which are comprised of host water molecules and guest ions, make them suitable for applications in EDLC electrolytes, owing to their high proton conductivities and thermal stabilities. The carbon materials in the ICH Me4NOH ? 5 H2O show a high specific capacitance, reversible charge–discharge behavior, and a long cycle life. The ionic‐hydrate complex provides the following advantages in comparison with conventional aqueous and polymer electrolytes: 1) The ICH does not cause leakage problems under normal EDLC operating conditions. 2) The hydrate material can be utilized itself, without requiring any pre‐treatments or activation for proton conduction, thus shortening the preparation procedure of the EDLC. 3) The crystallization of the ICH makes it possible to tailor practical EDLC dimensions because of its fluidity as a liquid hydrate. 4) The hydrate solid electrolyte exhibits more‐favorable electrochemical stability than aqueous and polymer electrolytes. Therefore, ICH materials are expected to find practical applications in versatile energy devices that incorporate electrochemical systems. 相似文献
142.
Numerous types of cells have been shown to undergo apoptosis when exposed to oxidant agent such as hydrogen peroxide. In order to understand the functional relationship between the anti- and pro-apoptotic regulatory proteins in the cells under oxidant stress, we have studied the level of expression of apoptosis regulatory proteins, bcl-2 and bax, in human leukemia HL-60 cells. The exposure of HL-60 cells to different concentrations of H2O2 for 6 h resulted in a typical apoptosis of the cells as characterized by flow cytometry, cell cycle analysis, and DNA fragmantation. There was a block in G1 to S transition and apoptotic cells were mainly derived from S and G2 cells. Kinetic study demonstrated that the levels of both bcl-2-mRNA and -protein expression were decreased with the progression of cellular apoptosis whereas the level of bax-mRNA was unchanged but the expressed bax-protein was not detectable. Cycloheximide, a nonspecific translation inhibitor, did not prevent the hydrogen peroxide-mediated apoptosis in HL-60 cells. These results suggest that the regulation of bcl-2, but not of bax are important factor in the oxidative stress-induced apoptosis in HL-60 cells. 相似文献
143.
Jae-Myung Lee Won-Seok Chang Byeong-Chul Yu Hansu Kim Dongmin Im Seok-Gwang Doo Hun-Joon Sohn 《Electrochemistry communications》2010,12(7):928-932
A Sn2Fe/C nanocomposite containing Cu was evaluated as an anode material for rechargeable lithium-ion batteries. The electrochemical reaction mechanism of this nanocomposite was examined by ex-situ X-ray diffraction and high resolution transmission electron microscopy. The Sn2Fe/C nanocomposite containing Cu showed dramatically improved cycling performance. The enhanced cyclability of the Sn2Fe/C nanocomposite containing Cu was attributed to both amorphization of the Sn2Fe phase and a recombination reaction between Sn and Cu during the charging step. 相似文献
144.
Sung Hee Yoon Sun Ok Yun Jung Yong Park Hee Yeun Won Eun-Kyung Kim Hyun-Jung Sohn Hyun-Il Cho Tai-Gyu Kim 《Experimental & molecular medicine》2009,41(3):161-170
Increasing importance is being given to the stimulation of Th1 response in cancer immunotherapy because its presence can shift the direction of adaptive immune responses toward protective immunity. Based on chemokine receptor expression, CXCR3+CCR4-CD4+ T cells as Th1-type cells were investigated its capacity in monocyte-derived dendritic cell (DC) maturation and polarization, and induction of antigen specific cytotoxic T lymphocytes (CTL) in vitro. The levels of IL-4, IL-5 and IL-10 were decreased to the basal level compared with high production of IFN-γ, TNF-α, and IL-2 in CXCR3+CCR4-CD4+ T cells stimulated with anti-CD3 and anti-CD28 antibodies. Co-incubation of activated CD4+ or CXCR3+CCR4-CD4+ T cells with DC (CD4+/DC or CXCR3+CD4+/DC, respectively) particularly up-regulated IL-12 and CD80 expression compared with DC matured with TNF-α and LPS (mDC). Although there was no significant difference between the effects of the CXCR3+CCR4-CD4+ and CD4+ T cells on DC phenotype expression, CXCR3+CD4+/DC in CTL culture were able to expand number of CD8+ T cells and increased frequencies of IFN-γ secreting cells and overall cytolytic activity against tumor antigen WT-1. These results demonstrated that the selective addition of CXCR3+CCR4-CD4+ T cells to CTL cultures could enhance the induction of CTLs by DC in vitro, and implicated on a novel strategy for adoptive T cell therapy. 相似文献
145.
A Goodey J J Lavigne S M Savoy M D Rodriguez T Curey A Tsao G Simmons J Wright S J Yoo Y Sohn E V Anslyn J B Shear D P Neikirk J T McDevitt 《Journal of the American Chemical Society》2001,123(11):2559-2570
The development of a chip-based sensor array composed of individually addressable polystyrene-poly(ethylene glycol) and agarose microspheres has been demonstrated. The microspheres are selectively arranged in micromachined cavities localized on silicon wafers. These cavities are created with an anisotropic etch and serve as miniaturized reaction vessels and analysis chambers. A single drop of fluid provides sufficient analysis media to complete approximately 100 assays in these microetch pits. The cavities possess pyramidal pit shapes with trans-wafer openings that allows for both fluid flow through the microreactors/analysis chambers and optical access to the chemically sensitive microspheres. Identification and quantitation of analytes occurs via colorimetric and fluorescence changes to receptor and indicator molecules that are covalently attached to termination sites on the polymeric microspheres. Spectral data are extracted from the array efficiently using a charge-coupled device allowing for the near-real-time digital analysis of complex fluids. The power and utility of this new microbead array detection methodology is demonstrated here for the analysis of complex fluids containing a variety of important classes of analytes including acids, bases, metal cations, metabolic cofactors, and antibody reagents. 相似文献
146.
N-Heterocyclic carbenes, prepared in situ from diarylimidazolium salts, serve as highly effective catalysts for the generation of reactive homoenolates from alpha,beta-unsaturated aldehydes. The catalyst-bound homoenolate reacts with electrophilic aldehydes leading, via the key intermediacy of an activated carboxylate, to gamma-butyrolactones in good yields and stereoselectivities. Importantly, this process demonstrates an unprecedented reaction mode for the generation of nucleophilic carbanions with a multifunctional organocatalyst under exceptionally mild and convenient reaction conditions. 相似文献
147.
Ho Cheol Jeong Suk Hyun Lim Youngku Sohn Young-Il Kim Hoeun Jang Dae Won Cho Patrick S. Mariano 《Tetrahedron letters》2017,58(10):949-954
Single electron transfer (SET)-promoted photoaddition reactions between fullerene C60 and both various alkyl (Me, Et, i-Pr, t-Bu)- and para-substituted (p-Me, p-OMe, p-F, p-CF3) arene ring containing, N-α-trimethylsilyl-N-alkyl-N-benzylamines were explored to gain information about photoproduct profiles and how the electronic and steric nature of the amine substrates influence reaction efficiencies. The results show that visible light (λ > 540 nm) irradiation of 10% EtOH-toluene solutions containing C60 and N-α-trimethylsilyl-N-alkyl-N-benzylamines produce 1-aminomethyl-1,2-dihydrofullerenes as a sole photoproduct. In addition, SET-promoted photoaddition reactions of unsubstituted and para-electron donating group substituted arene ring containing N-α-trimethylsilyl-N-alkyl-N-benzylamines take place to give photoproducts more efficiently than those containing para-electron withdrawing group substituted arene rings. Moreover, although steric factors are less significant than the electronic nature of the amine substrates in governing reaction efficiencies, sterics do play a significant role in photoreactions of electron deficient amine substrates. 相似文献
148.
We introduce an unsplit staggered mesh scheme (USM) for multidimensional magnetohydrodynamics (MHD) that uses a constrained transport (CT) method with high-order Godunov fluxes and incorporates a new data reconstruction–evolution algorithm for second-order MHD interface states. In this new algorithm, the USM scheme includes so-called “multidimensional MHD terms”, proportional to , in a dimensionally-unsplit way in a single update. This data reconstruction–evolution step, extended from the corner transport upwind (CTU) approach of Colella, maintains in-plane dynamics very well, as shown by the advection of a very weak magnetic field loop in 2D. This data reconstruction–evolution algorithm is also of advantage in its consistency and simplicity when extended to 3D. The scheme maintains the constraint by solving a set of discrete induction equations using the standard CT approach, where the accuracy of the computed electric field directly influences the quality of the magnetic field solution. We address the lack of proper dissipative behavior in the simple electric field averaging scheme and present a new modified electric field construction (MEC) that includes multidimensional derivative information and enhances solution accuracy. A series of comparison studies demonstrates the excellent performance of the full USM–MEC scheme for many stringent multidimensional MHD test problems chosen from the literature. The scheme is implemented and currently freely available in the University of Chicago ASC FLASH Center’s FLASH3 release. 相似文献
149.
Jongha Lee Yeonsun Sohn Jin Hoo Park Soohyung Lee Byung-Su Kim In-Su Park Pil Kim 《Current Applied Physics》2019,19(9):961-967
Titanium nitride (TiN) - graphene (G) nanocomposites are promising for electrochemical charge storage where a high content of Ti species is desired. Herein, we propose an effective method for the preparation of TiN-G nanocomposites with a high concentration of Ti species. These nanocomposites can be successfully achieved through a further deposition of Ti on Ti-graphene oxide (GO) or a thermally exfoliated Ti-GO. Depending on the annealing condition employed (NH3 and N2), two types of TiN-G nanocomposites (NH3 annealing for TiN/G and TiN/G-TE, TE: thermal exfoliation) and a TiO2-G nanocomposite (N2 annealing for TiO2/G-TE) were prepared. These nanocomposites were then investigated for potential application as an electrochemical supercapacitor. Compare with TiO2/G-TE, the TiN-G nanocomposites both exhibited a higher specific capacitance, although one of these nanocomposites had a lower surface area than TiO2/G-TE. Among the nanocomposites prepared, TiN/G-TE delivered the best electrochemical performance. The relationship between the physical properties and the capacitive performance of the nanocomposites were systematically evaluated. 相似文献
150.
Transition metal complexes have been extensively used as catalysts for organophosphorus agent decomposition to reduce their toxicity with their performance being strongly dependent on the nature of the metal ion. To investigate this dependence, we prepared dipicolylamine (DPA)‐containing complexes of Cu(II), Zn(II), Ni(II), Co(II), and Fe(II) and analyzed their activities for the degradation of diisopropyl fluorophosphate (DFP), a nerve agent surrogate compound. Cu(II)‐DPA complex showed fastest reaction kinetics while Zn(II)‐DPA and Ni(II)‐DPA exhibited more slower reactions. This observation can be explained using frontier molecular orbital (FMO) theory, which revealed that the nucleophilicity of the oxygen atom in water molecules in these transition metal complexes was well matched with reactivity order observed in experiments. These investigations combined with theoretical study provide valuable information for designing and predicting the activity of new transition metal–organic ligand complexes as a catalyst to decompose and reduce toxicity of organophosphorus nerve agents. 相似文献