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Xia X Zeng J McDearmon B Zheng Y Li Q Xia Y 《Angewandte Chemie (International ed. in English)》2011,50(52):12542-12546
Shaped and dimpled: Silver nanocrystals enclosed by concave surfaces and thus high-index facets have been prepared by simply controlling the growth habit of Ag cubic seeds. Four types of concave nanocrystals, including octahedron, cube, octapod, and trisoctahedron, were obtained (see picture). 相似文献
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We report an improved method for the preparation of trichloromethylcarbinols from enolizable ketones. Trichloromethylcarbinols were obtained in good to excellent yields by using of a combination of CHCl3, n-BuLi, and chlorotitanium (IV) triisopropoxide. Hydrolysis of the trichloromethylcarbinol to an α,β-unsaturated ester was also explored. 相似文献
4.
Xuezhong Jiang Greg Philan Brenden Carlson Sen Liu Larry Dalton Alex K-Y. Jen 《Macromolecular Symposia》2002,186(1):171-176
Pure and efficient red light-emitting diodes based on novel europium (Eu) and osmium (Os) complexes were demonstrated. The Eu complex, with dendron substituted diketone ligands, exhibits high photoluminescence efficiency of 45%. When a copolymer containing carbazole and 1,3,4-oxadiazole groups was used as the host, narrow electroluminescence at 617 nm was achieved, with a full width at half maximum of 4 nm and a maximum external quantum efficiency (η) of 0.80%. The Os complex shows pure red emission peaking at 650 nm. The Commission Internationale de l'Eclairage (CIE) chromaticity coordinates (x, y) are (0.65, 0.33). Maximum η and brightness achieved were 0.82% and 590 cd/m2, respectively. 相似文献
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Brenden P. Epps Pablo Valdivia y Alvarado Kamal Youcef-Toumi Alexandra H. Techet 《Experiments in fluids》2009,47(6):927-939
Digital particle image velocimetry and fluorescent dye visualization are used to characterize the performance of fish-like
swimming robots. During nominal swimming, these robots produce a ‘V’-shaped double wake, with two reverse-Kármán streets in
the far wake. The Reynolds number based on swimming speed and body length is approximately 7500, and the Strouhal number based
on flapping frequency, flapping amplitude, and swimming speed is 0.86. It is found that swimming speed scales with the strength
and geometry of a composite wake, which is constructed by freezing each vortex at the location of its centroid at the time of shedding. Specifically, we find
that swimming speed scales linearly with vortex circulation. Also, swimming speed scales linearly with flapping frequency
and the width of the composite wake. The thrust produced by the swimming robot is estimated using a simple vortex dynamics
model, and we find satisfactory agreement between this estimate and measurements made during static load tests. 相似文献
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[reaction: see text] Simple 1,4-dien-3-ones and 1,3-dienes react in the presence of BF(3).OEt(2) via a domino Nazarov electrocyclization/intermolecular [4 + 3]-cycloaddition sequence to furnish keto-bridged cyclooctenes in good yield. Most cases showed high diastereofacial selectivity and/or endo/exo selectivity, and surprising levels of regioselectivity were observed when isoprene was used as the diene partner. 相似文献
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Brenden McDearmon Eunhee Lim Kathryn O'Hara Hidenori Nakayama Yingdong Luo Michael L. Chabinyc Craig J. Hawker 《Journal of polymer science. Part A, Polymer chemistry》2017,55(16):2618-2628
A new pentacyclic building block, benzodibenzofuranquinone (BDBFQ), is synthesized in a single step from the inexpensive and readily available feedstocks chloranil and 3‐bromophenol. This versatile repeat unit is incorporated into a series of conjugated materials as either the redox active quinone form or as an electron‐rich dialkylated benzodibenzofuran (BDBF) unit. To illustrate the performance that can be obtained from these systems, optical and electrochemical properties were studied via UV–vis–NIR spectroscopy and cyclic voltammetry. Thin‐film morphology was characterized via grazing incidence wide‐angle X‐ray scattering with thin‐film field‐effect transistor measurements further demonstrating the utility of this system. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 2618–2628 相似文献
8.
The relationship between the maneuvering kinematics of a Giant Danio (Danio aequipinnatus) and the resulting vortical wake is investigated for a rapid, ‘C’-start maneuver using fully time-resolved (500 Hz) particle
image velocimetry (PIV). PIV illuminates the two distinct vortices formed during the turn. The fish body rotation is facilitated
by the initial, or “maneuvering” vortex formation, and the final fish velocity is augmented by the strength of the second,
“propulsive” vortex. Results confirm that the axisymmetric vortex ring model is reasonable to use in calculating the hydrodynamic
impulse acting on the fish. The total linear momentum change of the fish from its initial swimming trajectory to its final
swimming trajectory is balanced by the vector sum of the impulses of both vortex rings. The timing of vortex formation is
uniquely synchronized with the fish motion, and the choreography of the maneuver is addressed in the context of the resulting
hydrodynamic forces. 相似文献
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The kagome metals AV3Sb5(A=K,Rb,Cs)under ambient pressure exhibit an unusual charge order,from which superconductivity emerges.In this work,by applying hydrostatic pressure using a liquid pressure medium and carrying out electrical resistance measurements for RbV3Sb5,we find that the charge order becomes suppressed under a modest pressure pc(1.4 GPa3Sb5.Our findings point to qualitatively similar temperature-pressure phase diagrams in KV3Sb5 and RbV3Sb5,{and suggest a close link}between the second superconducting dome and the high-pressure resistance anomalies. 相似文献
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All compact AC(σ) operators have a representation analogous to that for compact normal operators. As a partial converse we obtain conditions
which allow one to construct a large number of such operators. Using the results in the paper, we answer a number of questions
about the decomposition of a compact AC(σ) operator into real and imaginary parts.
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