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81.
Whitney's theorem on 2-isomorphism characterizes the set of graphs having the same cycles as a given graph, where a cycle is regarded as a set of edges. In this paper, vertex 2-isomorphism is defined and used to prove a vertex analogue of Whitney's theorem. The main theorem states that two connected graphs have the same set of cycles, where a cycle is now regarded as a set of vertices, if and only if one can be obtained from the other by a sequence of simple operations. © 1992 John Wiley & Sons, Inc. 相似文献
82.
Israel V. Muthu Vijayan Enoch Meenakshisundaram Swaminathan 《Journal of inclusion phenomena and macrocyclic chemistry》2005,53(3):149-154
The absorption and fluorescence spectral characteristics of 2-aminodiphenylsulphone (2ADPS) have been investigated in the presence of β-cyclodextrin (β-CDx) in water. Dual emission is observed upon the complexation of 2ADPS in β-CDx. The stoichiometry of the host:guest inclusion complex is found to be 2:1. Steady state and time-resolved fluorescence spectral analysis support the formation of 2:1 complex between β-CDx and 2ADPS. The large enhancement in fluorescence intensity of twisted intramolecular charge transfer (TICT) band in aqueous β-CDx solution is due to the decrease in non-radiative processes. The ground and the excited state pKa values for the monocation-neutral equilibrium of 2ADPS in β-CDx are found to be different from the pKa values in aqueous solution. In the presence of β-CDx, 2ADPS is found to be less basic in the ground and the excited states. 相似文献
83.
Bhavana Gupta Lin Zhang Ambrose Ashwin Melvin Bertrand Goudeau Laurent Bouffier Alexander Kuhn 《Chemical science》2021,12(6):2071
Rational design and shaping of soft smart materials offer potential applications that cannot be addressed with rigid systems. In particular, electroresponsive elastic materials are well-suited for developing original active devices, such as pumps and actuators. However, applying the electric stimulus requires usually a physical connection between the active part and a power supply. Here we report about the design of an electromechanical system based on conducting polymers, enabling the actuation of a wireless microfluidic pump. Using the electric field-induced asymmetric polarization of miniaturized polypyrrole tubes, it is possible to trigger simultaneously site-specific chemical reactions, leading to shrinking and swelling in aqueous solution without any physical connection to a power source. The complementary electrochemical reactions occurring at the opposite extremities of the tube result in a differential change of its diameter. In turn, this electromechanical deformation allows inducing highly controlled fluid dynamics. The performance of such a remotely triggered electrochemically active soft pump can be fine-tuned by optimizing the wall thickness, length and inner diameter of the material. The efficient and fast actuation of the polymer pump opens up new opportunities for actuators in the field of fluidic or microfluidic devices, such as controlled drug release, artificial organs and bioinspired actuators.Tubular conducting polymer actuators are used for developing a wireless electropumping device. Bipolar electrochemistry, allowing symmetry breaking in terms of polarization and electrochemical reactions, is the key ingredient for efficient pumping. 相似文献
84.
Rudhramyna GnaneshwarPrakash P. Wadgaonkar Swaminathan Sivaram 《Tetrahedron letters》2003,44(32):6047-6049
The Michael addition of a β,β-dimethyl substituted silyl ketene acetal [Me2CC(OMe)OSiMe3] to α,β-unsaturated ketones, namely, 2-cyclopentenone, 2-cyclohexenone, 3-methyl-2-cyclohexenone, isophorone, methyl vinyl ketone and mesityl oxide occurs smoothly in the presence of the nucleophilic catalyst, tetra-n-butyl ammonium bibenzoate (TBABB) in THF giving the corresponding 1,4-adducts in excellent yields. 相似文献
85.
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87.
4H‐cyclopenta[2,1‐b:3,4‐b′]dithiophen‐4‐one (CPDTO) homopolymer with side chains on every other CPDTO
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Jianyuan Sun Swaminathan Venkatesan Ashish Dubey Qiquan Qiao Cheng Zhang 《Journal of polymer science. Part A, Polymer chemistry》2017,55(6):1077-1085
A soluble 4H‐cyclopenta[2,1‐b ;3,4‐b ′]dithiophene‐4‐one (CPDTO)‐based polymer (C6‐PCPDTO) has been synthesized from two monomers derived from nonalkylated CPDTO and didodecyl CPDTO (C12‐CPDTO). Proton NMR, thermal analysis, UV–vis absorption, cyclic voltammetry, and XRD are used to characterize the polymer in solution and film. The new polymer has an optical bandgap of 1.28 eV in film, and has strong interchain interaction in chloroform solutions. The polymer contains a significant amount of homocoupled segments. The regular segments and homocoupled CPDTO segments render the polymer highly aggregating in solution. The non‐planar homocoupled C12‐CPDTO segments prevent the polymer from forming regular π‐stacks, resulting in a low SCLC hole mobility (3.88 × 10?7 cm2V?1s?1). CV experiments show that C6‐PCPDTO is stable in its oxidized and reduced states. Solar cell devices were fabricated from C6‐PCPDTO2 :PC60BM blends of different weight ratios. High PC60BM loading (80% or greater) was required for the devices to show measurable efficiency, indicating that the limited π‐stacking of the polymer is not sufficient to cause effective phase separation. Further development of synthetic method is still needed to eliminate structural defects so that long‐range ordered pi‐stacking can be realized in the polymer for these applications. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 1077–1085 相似文献
88.
Kavya Swaminathan Jeffrey C. Dyason Andrea Maggioni Mark von Itzstein Kevin M. Downard 《Analytical and bioanalytical chemistry》2013,405(20):6563-6572
The binding of a natural anthocyanin to influenza neuraminidase has been studied employing mass spectrometry and molecular docking. Derived from a black elderberry extract, cyanidin-3-sambubiocide has been found to be a potent inhibitor of sialidase activity. This study reveals the molecular basis for its activity for the first time. The anthocyanin is shown by parallel experimental and computational approaches to bind in the so-called 430-cavity in the vicinity of neuraminidase residues 356–364 and 395–432. Since this antiviral compound binds remote from Asp 151 and Glu 119, two residues known to regulate neuraminidase resistance, it provides the potential for the development of a new class of antivirals against the influenza virus without this susceptibility. 相似文献
89.
Rheological material functions are used to form our conceptual understanding of a material response. For a nonlinear rheological response, the possible deformation protocols and material measures span a high-dimensional space. Here, we use asymptotic expansions to outline low-dimensional measures for describing leading-order nonlinear responses in large amplitude oscillatory shear (LAOS). This amplitude-intrinsic regime is sometimes called medium amplitude oscillatory shear (MAOS). These intrinsic nonlinear material functions are only a function of oscillatory frequency, and not amplitude. Such measures have been suggested in the past, but here, we clarify what measures exist and give physically meaningful interpretations. Both shear strain control (LAOStrain) and shear stress control (LAOStress) protocols are considered, and nomenclature is introduced to encode the physical interpretations. We report the first experimental measurement of all four intrinsic shear nonlinearities of LAOStrain. For the polymeric hydrogel (polyvinyl alcohol - Borax) we observe typical integer power function asymptotics. The magnitudes and signs of the intrinsic nonlinear fingerprints are used to conceptually model the mechanical response and to infer molecular and microscale features of the material. 相似文献
90.
Peter G. Jones Henning Hopf Cornelia Mlynek Vijay Narayanan Swaminathan 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(12):o723-o725
In benzene‐1,2,3‐tricarbonitrile, C9H3N3, the packing of the two independent molecules is three‐dimensional and complex, involving inter alia bifurcated (C—H)2...N systems from neighbouring CH groups. In [2.2]paracyclophane‐4,5,12,13‐tetracarbonitrile, C20H12N4, the [2.2]paracyclophane systems display the usual distortions, namely lengthened C—C bonds and widened sp3 angles in the bridges, narrow angles in the six‐membered rings at the bridgehead atoms, and flattened boat conformations of the rings. The molecules are linked by a series of C—H...N interactions to form layers parallel to the ab plane. 相似文献