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931.
The thermal and electrical conductivity and mechanical properties of polyetherimide (PEI) containing either alkyl‐aminated (enGO) or phenyl‐aminated graphene (pnGO) oxides were studied. A solution casting method was used to prepare functionalized graphene oxide/PEI composites with different filler contents. The introduction of functionalized graphene oxide to the PEI matrix improved the thermal conductivity, electrical conductivity, and mechanical properties. The thermal conductivities of the enGO 3 wt%/PEI and pnGO 3 wt%/PEI composites were 0.324 W/mK and 0.329 W/mK, respectively, due to the high thermal conductivity of the graphene‐based materials and the strong interface adhesion due to the filler surface treatment between the fillers and the matrix. The electrical conductivities of the functionalized graphene oxide/PEI composites were larger than that of PEI, but the electrical conductivity values were generally low, which is consistent with the magnitude of the insulator. The strong interfacial adhesion between the fillers and the matrix led to improved mechanical properties. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
932.
Dina V. Hingorani Dr. Byunghee Yoo Adam S. Bernstein Dr. Mark D. Pagel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(32):9840-9850
This review focuses on exogenous magnetic resonance imaging (MRI) contrast agents that are responsive to enzyme activity. Enzymes can catalyze a change in water access, rotational tumbling time, the proximity of a 19F‐labeled ligand, the aggregation state, the proton chemical‐exchange rate between the agent and water, or the chemical shift of 19F, 31P, 13C or a labile 1H of an agent, all of which can be used to detect enzyme activity. The variety of agents attests to the creativity in developing enzyme‐responsive MRI contrast agents. 相似文献
933.
Reverse Micelle Synthesis of Colloidal Nickel–Manganese Layered Double Hydroxide Nanosheets and Their Pseudocapacitive Properties
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Hwansu Sim Changshin Jo Prof. Taekyung Yu Eunho Lim Prof. Songhun Yoon Prof. Jung Heon Lee Prof. Jibeom Yoo Prof. Jinwoo Lee Prof. Byungkwon Lim 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(45):14880-14884
Colloidal nanosheets of nickel–manganese layered double hydroxides (LDHs) have been synthesized in high yields through a facile reverse micelle method with xylene as an oil phase and oleylamine as a surfactant. Electron microscopy studies of the product revealed the formation of colloidal nanoplatelets with sizes of 50–150 nm, and X‐ray diffraction, energy dispersive X‐ray spectroscopy, and X‐ray photoelectron spectroscopy studies showed that the Ni–Mn LDH nanosheets had a hydrotalcite‐like structure with a formula of [Ni3Mn(OH)8](Cl?) ? n H2O. We found that the presence of both Ni and Mn precursors was required for the growth of Ni‐Mn LDH nanosheets. As pseudocapacitors, the Ni–Mn LDH nanosheets exhibited much higher specific capacitance than unitary nickel hydroxides and manganese oxides. 相似文献
934.
Palladium particles were simply synthesized using various ionic liquids. The morphology of the particles was significantly affected by the anion parts of the ionic liquids. Among the ionic liquids, hexafluorophosphate as an anion part was more effective in forming the palladium particles with relatively small and narrow size distribution. However, irregularly shaped palladium particles were synthesized without ionic liquid assistance. For a hexafluoropropylene hydrogenation to produce hydrofluorocarbons, palladium was impregnated on a carbon powder as a catalyst. During the preparation of the catalyst, ionic liquids were added to control the shape of the palladium on the support. After calcinations at 500 °C, all catalysts possessed the comparable crystal structure. Under identical reaction conditions, the catalyst prepared using 1-hexyl-3-methylimidazolium hexafluorophosphate was the most effective in this reaction. Hence, catalytic activity was mainly determined by the size of the palladium particles. 相似文献
935.
Kwang Ho Yoo Tae Rin Kwon So Young Kim Yi Seop Song Young Sook Cheon Yu Mi Kim In Kwon Yeo Eun Jung Ko Kapsok Li Myeung Nam Kim Beom Joon Kim 《Photochemistry and photobiology》2014,90(6):1423-1426
Ablative fractional carbon dioxide (CO2) lasers have been widely used for several types of cosmetic dermatosis. A number of previous studies have evaluated this technique in animals or human beings by observing morphologic changes using an invasive modality such as skin biopsy. In this study, we assessed in vivo skin changes after CO2 ablative fractional laser treatment in a mouse model using noninvasive imaging modalities (Folliscope® and Visioscan 98®), and each results was compared with data from histologic examination. An ablative fractional CO2 laser was applied with different pulse energy between 7 to 35 mJ/microspot. As results of above methods, we also confirmed that the CO2 ablative fractional laser generated injuries with increasing width and depth with increasing pulse energy. Although numerous papers have described application of this laser in vivo skin specimens, our study evaluated the feasibility of using relative noninvasive imaging modalities for assessing the outcome of laser ablation. Based on our data, we suggest that these technologies may be useful alternative modalities for assessing laser ablation that are easier to perform and less invasive than skin biopsy. 相似文献
936.
Visible‐Light‐Mediated Chan–Lam Coupling Reactions of Aryl Boronic Acids and Aniline Derivatives
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Dr. Woo‐Jin Yoo Tatsuhiro Tsukamoto Prof. Dr. Shū Kobayashi 《Angewandte Chemie (International ed. in English)》2015,54(22):6587-6590
The copper(II)‐catalyzed aerobic oxidative coupling reaction between aryl boronic acids and aniline derivatives was found to be improved significantly under visible‐light‐mediated photoredox catalysis. The substrate scope of this oxidative Chan–Lam reaction was thus expanded to include electron‐deficient aryl boronic acids as viable starting materials. 相似文献
937.
938.
Takayuki Atago Akihiro Tanaka Tomoyuki Kawamura Noritada Matsuo Yoo Tanabe 《Tetrahedron: Asymmetry》2009,20(9):1015-1019
We have developed an efficient practical resolution method for (1R,3R)-trans-chrysanthemic acid 1 and (1R,3S)-trans-2,2-dimethyl-3-(2,2-dichloroethenyl)cyclopropanecarboxylic acid 2, based on the preliminary results of the simpler analogues, (1R)-2,2-dichlorocyclopropanecarboxylic acid 3 and (1R)-2,2-dimethylcyclopropanecarboxylic acid 4, using a crystalline-liquid separation procedure (without column chromatography) with chiral 1,1′-binaphthol monoethyl ethers (R)-5b as the key auxiliary. Direct esterifications of 1, 2, 3, and 4 with (R)-5b gave four sets of (1R)- and (1S)-diastereomeric esters 8, 9, 6, and 7, respectively, with markedly different melting points. All of these diastereomers were easily obtained using a simple and one-step crystalline-liquid separation. The separated diastereomers 8 and 9 were easily hydrolyzed to the desired enantiopure acids 1 (>98%) and 2 (>99%), respectively, with recovery of (R)-5b (>90%). 相似文献
939.
N. R. Amundson A. Caboussat J. W. He J. H. Seinfeld K. Y. Yoo 《Journal of Optimization Theory and Applications》2006,128(3):469-498
A general equilibrium model for multiphase multicomponent inorganic atmospheric aerosols is proposed. The thermodynamic equilibrium is given by the minimum of the Gibbs free energy for a system involving an aqueous phase, a gas phase, and solid salts. A primal-dual algorithm solving the Karush-Kuhn-Tucker conditions is detailed. An active set/Newton method permits to compute the minimum of the energy and tracks the presence or not of solid salts at the equilibrium. Numerical results show the efficiency of our algorithm for the prediction of multiphase multireaction chemical equilibria.Communicated by R. GlowinskiThis work has been partially supported by the United States Environmental Protection Agency through Cooperative Agreement X-83234201 to the University of Houston. The second author was supported by the Swiss National Science Foundation, Grant PBEL2-103152. 相似文献
940.