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991.
Michael J. Strauss Darya Asheghali Austin M. Evans Rebecca L. Li Anton D. Chavez Chao Sun Matthew L. Becker William R. Dichtel 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(41):14850-14856
Nanotubes assembled from macrocyclic precursors offer a unique combination of low dimensionality, structural rigidity, and distinct interior and exterior microenvironments. Usually the weak stacking energies of macrocycles limit the length and mechanical strength of the resultant nanotubes. Imine‐linked macrocycles were recently found to assemble into high‐aspect ratio (>103), lyotropic nanotubes in the presence of excess acid. Yet these harsh conditions are incompatible with many functional groups and processing methods, and lower acid loadings instead catalyze macrocycle degradation. Here we report pyridine‐2,6‐diimine‐linked macrocycles that assemble into high‐aspect ratio nanotubes in the presence of less than 1 equiv of CF3CO2H per macrocycle. Analysis by gel permeation chromatography and fluorescence spectroscopy revealed a cooperative self‐assembly mechanism. The low acid concentrations needed to induce assembly enabled nanofibers to be obtained by touch‐spinning, which exhibit higher Young's moduli (1.33 GPa) than many synthetic polymers and biological filaments. These findings represent a breakthrough in the design of inverse chromonic liquid crystals, as assembly under such mild conditions will enable the design of structurally diverse and mechanically robust nanotubes from synthetically accessible macrocycles. 相似文献
992.
Guangze Yang Yun Liu Haofei Wang Russell Wilson Yue Hui Lei Yu David Wibowo Cheng Zhang Andrew K. Whittaker Anton P. J. Middelberg Chun‐Xia Zhao 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(40):14495-14502
A large range of nanoparticles have been developed to encapsulate hydrophobic drugs. However, drug loading is usually less than 10 % or even 1 %. Now, core–shell nanoparticles are fabricated having exceptionally high drug loading up to 65 % (drug weight/the total weight of drug‐loaded nanoparticles) and high encapsulation efficiencies (>99 %) based on modular biomolecule templating. Bifunctional amphiphilic peptides are designed to not only stabilize hydrophobic drug nanoparticles but also induce biosilicification at the nanodrug particle surface thus forming drug‐core silica–shell nanocomposites. This platform technology is highly versatile for encapsulating various hydrophobic cargos. Furthermore, the high drug loading nanoparticles lead to better in vitro cytotoxic effects and in vivo suppression of tumor growth, highlighting the significance of using high drug‐loading nanoparticles. 相似文献
993.
Shatsauskas Anton L. Saibulina Elina R. Gatilov Yurii V. Kostyuchenko Anastasia S. Fisyuk Alexander S. 《Chemistry of Heterocyclic Compounds》2019,55(11):1080-1086
Chemistry of Heterocyclic Compounds - Reactivity of 2-methyl-6-phenylbenzo[c][1,7]naphthyridine in alkylation, oxidation, and electrophilic substitution reactions has been studied. The reaction of... 相似文献
994.
Aksenov Nicolai A. Skomorokhov Anton A. Aksenov Alexander V. Voskressensky Leonid G. Rubin Michael A. 《Chemistry of Heterocyclic Compounds》2019,55(6):541-546
Chemistry of Heterocyclic Compounds - Synthetic approach toward indole derivatives bearing 2-nitroethyl group and polar azole moiety has been developed. This method involves conjugate addition of... 相似文献
995.
Felicia Phei Lin Lim Giuseppe Luna Khai Ching Tan Edward R.T. Tiekink Anton V. Dolzhenko 《Tetrahedron》2019,75(15):2322-2329
3-Amino-substituted 5-aminopyrazoles were found to be suitable substrates for the synthesis of new 4-aminopyrazolo[1,5-a][1,3,5]triazines (5-aza-9-deaza-adenines) when used in the one-pot, three-component reaction with cyanamide and triethyl orthoformate under microwave irradiation. The reaction proceeded selectively and its scope was demonstrated by the preparation of a library of 4-aminopyrazolo[1,5-a][1,3,5]triazines. Some structural aspects of the prepared compounds were investigated using dynamic NMR spectroscopy and X-ray crystallography. The operational simplicity, short reaction time, and good reproducibility are attractive features of the developed robust and practical approach for the synthesis of 7-amino-substituted 4-aminopyrazolo[1,5-a][1,3,5]triazines. 相似文献
996.
We consider various \(A_{\infty }\)-algebras of differential (super)forms, which are related to gauge theories and demonstrate explicitly how certain reformulations of gauge theories lead to the transfer of the corresponding \(A_{\infty }\)-structures. In addition, for \(N=2\) 3D space, we construct the homotopic counterpart of the de Rham complex, which is related to the superfield formulation of the \(N=2\) Chern–Simons theory. 相似文献
997.
998.
Joris?P.?OosterhuisEmail author Anton?A.?Verbeek Simon?Bühler Douglas?Wilcox Theo?H.?van der Meer 《Flow, Turbulence and Combustion》2017,98(1):311-326
The effect of flow separation and turbulence on the performance of a jet pump in oscillatory flows is investigated. A jet pump is a static device whose shape induces asymmetric hydrodynamic end effects when placed in an oscillatory flow. This will result in a time-averaged pressure drop which can be used to suppress acoustic streaming in closed-loop thermoacoustic devices. An experimental setup is used to measure the time-averaged pressure drop as well as the acoustic power dissipation across two different jet pump geometries in a pure oscillatory flow. The results are compared against published numerical results where flow separation was found to have a negative effect on the jet pump performance in a laminar flow. Using hot-wire anemometry the onset of flow separation is determined experimentally and the applicability of a critical Reynolds number for oscillatory pipe flows is confirmed for jet pump applications. It is found that turbulence can lead to a reduction of flow separation and hence, to an improvement in jet pump performance compared to laminar oscillatory flows. 相似文献
999.
Eduard Feireisl Bum Ja Jin Antonín Novotny 《Journal of Mathematical Fluid Mechanics》2012,14(4):717-730
We introduce the notion of relative entropy for the weak solutions to the compressible Navier–Stokes system. In particular, we show that any finite energy weak solution satisfies a relative entropy inequality with respect to any couple of smooth functions satisfying relevant boundary conditions. As a corollary, we establish the weak-strong uniqueness property in the class of finite energy weak solutions, extending thus the classical result of Prodi and Serrin to the class of compressible fluid flows. 相似文献
1000.
Edward A. Karakhanov Lyusyen M. Karapetyan Yulia S. Kardasheva Anton L. Maksimov Elena A. Runova Maria V. Terenina Tatyana Yu. Filippova 《Macromolecular Symposia》2008,270(1):106-116
The results of studying a number of reactions catalyzed by system based on macrocyclic receptors are presented. Rh complexes with modified calix[6]- and calix[4]arene were active in the hydroformylation of unsaturated compounds. Ru catalytic system based on cucurbit[6]uril was studied in hydrogen transfer hydrogenation of water insoluble aldehydes. Molecular imprinting method application for design of catalytic systems based on cyclodextrins for naphthols dimerization and oxidative coupling styrene and benzene were discussed. 相似文献