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991.
The synthesis of novel 1‐(1H‐tetrazol‐5‐yl)‐10‐chloro‐1,2,3,4‐tetrahydropyrazino[1,2‐a] indole derivatives starting from the initially prepared 1‐(2‐bromoethyl)‐3‐chloro‐1H‐indole‐2‐carbaldehyde is described. A variety of likely biologically relevant pyrazino[1,2‐a] indole‐based 1,5‐disubstituted tetrazoles was obtained in moderate to high yields via an Ugi‐azide reaction. These reactions presumably proceed by the imine formation, intramolecular cyclization to iminium ion, and nucleophilic addition tandem reactions, respectively. 相似文献
992.
Alexander S. Balankin Alireza K. Golmankhaneh Julián Patiño-Ortiz Miguel Patiño-Ortiz 《Physics letters. A》2018,382(23):1534-1539
This Letter is focused on the impact of fractal topology on the transport processes governed by different kinds of random walks on Cantor tartans. We establish that the spectral dimension of the infinitely ramified Cantor tartan is equal to its fractal (self-similarity) dimension D. Consequently, the random walk on the Cantor tartan leads to a normal diffusion. On the other hand, the fractal geometry of Cantor tartans allows for a natural definition of power-law distributions of the waiting times and step lengths of random walkers. These distributions are Lévy stable if . Accordingly, we found that the random walk with rests leads to sub-diffusion, whereas the Lévy walk leads to ballistic diffusion. The Lévy walk with rests leads to super-diffusion, if , or sub-diffusion, if . 相似文献
993.
The free radical scavenging activity of lespedezacoumestan toward ˙OH radical: A quantum chemical and computational kinetics study
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The free radical activity of lespedezacoumestan was investigated toward hydroxyl (˙OH) radical in polar and nonpolar media using density functional theory. Four reaction mechanisms including radical adduct formation, hydrogen atom transfer, sequential single electron‐proton transfer (SET‐PT), and sequential proton loss electron transfer were considered. The rate constants and branching ratio for all possible sites of reaction were calculated and reported for the first time. According to the obtained results, lespedezacoumestan reacts faster with ˙OH radical in aqueous solution than in nonpolar media. Also, lespedezacoumestan is an excellent ˙OH radical scavenger regardless of the environment polarity. 相似文献
994.
995.
Zahra Sadat Aghayan Alireza Alfi J. A. Tenreiro Machado 《Mathematical Methods in the Applied Sciences》2020,43(17):10332-10345
This article investigates the robust stability of fractional order neutral-type systems involving nonlinear perturbations and time varying delays in the presence of input saturation. Design criteria, expressed in terms of linear matrix inequalities, are derived with the aid of the Lyapunov Krasovskii functional for the state feedback controller. Based on the cone complementarity linearization method, an optimization problem is also formulated for finding the controller gains subject to maximizing the domain of attraction. The main results are confirmed by numerical simulations. 相似文献
996.
Kargar Hadi Torabi Vajiheh Akbari Alireza Behjatmanesh-Ardakani Reza Sahraei Atefeh Tahir Muhammad Nawaz 《Structural chemistry》2019,30(6):2289-2299
Structural Chemistry - In the present study, an asymmetric tetradentate NOON Schiff base ligand 2,2′-((4-methyl-1,2-phenylene)bis(nitrilomethylylidene))bis(4-chlorophenol) (H2L) was... 相似文献
997.
Golnoush Mirzahosseini Azadeh Manayi Mahnaz Khanavi Maliheh Safavi Ali Salari Alireza Madjid Ansari 《Natural product research》2019,33(11):1687-1690
Centaurea bruguierana subsp. belangerana was extracted by 80% ethanol. The total extract was then partitioned into four fractions including chloroform, ethyl acetate and methanol. Cytotoxic effect of fractions was examined by MTT assay in K562 (chronic myelogenous leukemia), AGS (gastric adenocarcinoma), MCF-7 (breast adenocarcinoma) and SW742 (colon adenocarcinoma) cell lines. The Chloroform fraction, with the lowest LC50 against K-562 cell lines, was partitioned into 14 subfractions and subjected to further purification by reversed-phase (C18) silica gel and sephadex LH-20 column chromatography. Three flavonoids including cirsimaritin, cirsilinelol and eupatilin were isolated for the first time from the species and the structures were confirmed by spectroscopic data. The high selectivity index of the purified flavonoids indicates valuable components with potential few side effects for normal cell lines. However, solubility tests for isolated components indicates the need for novel pharmaceutical dosage forms, in the case for using natural flavonoids as chemotherapeutic agents. 相似文献
998.
Chenghao Wan Zhen Zhang David Woolf Colin M. Hessel Jura Rensberg Joel M. Hensley Yuzhe Xiao Alireza Shahsafi Jad Salman Steffen Richter Yifei Sun M. Mumtaz Qazilbash Rüdiger Schmidt‐Grund Carsten Ronning Shriram Ramanathan Mikhail A. Kats 《Annalen der Physik》2019,531(10)
The insulator‐to‐metal transition (IMT) in vanadium dioxide (VO2) can enable a variety of optics applications, including switching and modulation, optical limiting, and tuning of optical resonators. Despite the widespread interest in VO2 for optics, the wavelength‐dependent optical properties across its IMT are scattered throughout the literature, are sometimes contradictory, and are not available at all in some wavelength regions. Here, the complex refractive index of VO2 thin films across the IMT is characterized for free‐space wavelengths from 300 nm to 30 µm, using broadband spectroscopic ellipsometry, reflection spectroscopy, and the application of effective‐medium theory. VO2 films of different thicknesses are studied, on two different substrates (silicon and sapphire), and grown using different synthesis methods (sputtering and sol–gel). While there are differences in the optical properties of VO2 synthesized under different conditions, these differences are surprisingly small in the ≈2–11 µm range where the insulating phase of VO2 also has relatively low optical loss. It is anticipated that the refractive‐index datasets from this article will be broadly useful for modeling and design of VO2‐based optical and optoelectronic components, especially in the mid‐wave and long‐wave infrared. 相似文献
999.
Forsythe D Julian SR Bergemann C Pugh E Steiner MJ Alireza PL McMullan GJ Nakamura F Haselwimmer RK Walker IR Saxena SS Lonzarich GG Mackenzie AP Mao ZQ Maeno Y 《Physical review letters》2002,89(16):166402
We have measured the temperature and field dependence of the resistivity of the unconventional superconductor Sr2RuO4 at pressures up to 3.3 GPa. Using the Shubnikov-de Haas effect, we find that the Fermi surface sheet believed to be primarily responsible for superconductivity becomes more two-dimensional with increasing pressure, a surprising result that is, however, consistent with a recent model of orbital-dependent superconductivity in this system. Many-body enhancements and the superconducting transition temperature all fall gradually with increasing pressure, contrary to previous suggestions of a ferromagnetic quantum critical point at approximately 3 GPa. 相似文献
1000.
The vibration-rotation emission spectra of CdH2 and CdD2 molecules have been recorded at high resolution using a Fourier-transform spectrometer. The molecules were generated in a furnace-discharge emission source by reaction of cadmium vapor with molecular hydrogen or deuterium. The fundamental bands for the antisymmetric stretching mode (upsilon3) of CdH2 and CdD2 were detected at about 1771.5 and 1278.3 cm(-1), respectively. In addition, the 002(sigma(g)+)-001(sigma(u)+) and 01 l(pi(g))-010(pi(u)) hot bands were observed for CdH2. Spectroscopic constants were determined for each of the 12 observed isotopologs: 110CdH2, 111CdH2, 112CdH2, 113CdH2, 114CdH2, 116CdH2, 1l0CdD2, 111CdD2, 112CdD2, 113CdD2, 114CdD2, and 116CdD2. The average Cd-H and Cd-D bond distances (r0) were determined to be 1.683028(10) and 1.679161(16) angstroms, respectively. 相似文献