排序方式: 共有106条查询结果,搜索用时 15 毫秒
21.
In this paper we introduce the notion of a von Neumann-Schatten p-frame in separable Banach spaces and obtain some of their characterizations. We show that p-frames and g-frames are a class of von Neumann-Schatten p-frames. 相似文献
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Hooshmandi Kaveh Bayat Farhad Jahedmotlagh Mohamadreza Jalali Aliakbar 《Nonlinear dynamics》2020,100(1):731-748
Nonlinear Dynamics - This paper addresses the guaranteed cost sampled-data controller synthesis and analysis problems with application to nonlinear chaotic systems. A linear parameter-varying (LPV)... 相似文献
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Polymer-coated magnetic nanoparticles are emerging as a useful tool for a variety of applications, including catalysis. In the present study, fucoidan-coated magnetic graphene oxide was synthesized using a natural sulfated polysaccharide. The prepared BaFe12O19@GO@Fu (Fu=fucoidan, GO=graphene oxide) was characterized using Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray (EDX) analysis, vibrating sample magnetometry (VSM), thermogravimetric analysis (TGA), Raman spectroscopy, and X-ray diffraction (XRD). The catalytic proficiency of BaFe12O19@GO@Fu was investigated in the synthesis of 1,4-dihydropyridine and polyhydroquinoline derivatives. Excellent turnover numbers (TON) and turnover frequencies (TOF) (6330 and 25320 h−1) testify to the high efficiency of the catalyst. Moreover, the antimicrobial activity of BaFe12O19@GO@Fu was evaluated against Escherichia coli (E. coli), and Staphylococcus aureus (S. aureus) through the Agar well diffusion method, indicating that BaFe12O19@GO@Fu has antibacterial activity against S. aureus. 相似文献
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Aliakbar Dehno Khalaji Karla Fejfarova Michal Dusek Hamid Reza Bijanzadeh 《Journal of chemical crystallography》2011,41(12):1955-1960
Abstract
Synthesis and characterization of single crystals of a new organic Schiff-base derivative, N,N′-bis(2,3-dimethoxybenzylidene)-1,2-diaminoethane is reported. Good quality single crystals with size 10 mm × 1 mm × 1 mm were grown by slow evaporation technique from a methanol solution at room temperature. The grown crystals have been characterized by elemental analyses and functional groups were identified using FT-IR and 1H-NMR spectroscopy. Crystal structure of the title compound has been determined by single crystal X-ray diffraction. The title compound has a monoclinic symmetry, space group P21/c, lattice parameters are a = 4.4159(3) ?, b = 14.2333(9) ?, c = 15.0601(10) ?, β = 97.755(5)°, Z = 2, V = 937.91(11) ?3. 相似文献26.
Aliakbar Dehno Khalaji Matthias Weil Gholamhossein Grivani Samaneh Jalali Akerdi 《Monatshefte für Chemie / Chemical Monthly》2010,103(2):539-543
Abstract
In this study two zinc(II) halide complexes with the Schiff-base ligand (3,4-MeO-ba)2en [N,N′-bis(3,4-dimethoxybenzylidene)ethane-1,2-diamine] have been synthesized and characterized by elemental analyses (CHN), single-crystal X-ray diffraction, Fourier-transform infrared (FT-IR), and 1H nuclear magnetic resonance (NMR) spectroscopy. The metal-to-ligand ratio was found to be 1:1 within the formula ZnX2((3,4-MeO-ba)2en) (X = Br, I). Crystal structure analysis reveals that the coordination geometry around the zinc(II) ions in the two isotypic complexes is distorted tetrahedral. The Schiff-base ligand (3,4-MeO-ba)2en acts as a chelating ligand and coordinates via two N atoms to the metal center and adopts an (E,E) conformation. The coordination spheres of the metal atoms are completed by the two halide atoms, which are also involved in weak non-classical hydrogen-bonding interactions of the type C–H···X–Zn. 相似文献27.
In this paper, the p-version finite element method and its fictitious domain extension, the finite cell method, are extended to the finite strain J2 plasticity. High-order shape functions are used for the finite element approximation of volume-preserving plastic dominated deformations. The accuracy and efficiency of p-version elements and cells in the finite plastic strain range are evaluated by the computation of two benchmark problems. It is shown that they provide locking free behavior and simplified meshing. These results are verified in comparison with the results of h-version elements in F-bar formulation. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
28.
Matsuda and coworkers demonstrated that imidazopyridopyrimidine nucelobases (N N , O O , N O , tO O , and O N ) can mimic Watson–Crick nucleobase in forming H-bonds in DNA double helix. In the present study, we address the question about the strengths of the H-bonds in imidazopyridopyrimidine base pairs compared to those in Watson–Crick ones by focusing particularly on the nature of these interactions. Optimized structures of imidazopyridopyrimidine, imidazopyridopyrimidine–Watson–Crick, and Watson–Crick base pairs are obtained at the DFTB3LYP/6-311++G (d,p). The nature and strength of the intramolecular H-bonds in these base pairs have been investigated based on natural bond orbital (NBO method) to consider the effect of charge transfer, “atoms-in-molecules” (AIM) topological parameters, and decomposition of the interaction energies using the energy decomposition analysis (EDA). These investigations imply that N N –O O and N O –O N can form base pairs with four H-bonds (most stable than those of Watson–Crick base pairs) when they incorporated into DNA double helix. Furthermore, it can be deduced that O N and N N nucleobases form energetically more favorable pairs with adenine and guanine than the normal Watson–Crick counter parts. These results can be helpful for the stabilization and regulation of a variety of new base-pairing motif of DNA structures. 相似文献
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Gholamhossein Grivani Aliakbar Dehno Khalaji Karla Fejfarová Michal Dušek Vida Tahmasebi Shadi Delkhosh 《Journal of the Iranian Chemical Society》2014,11(4):953-962
A new oxidovanadium(IV) Schiff base complex, VOL2 (1), containing furfuryl pendant group was synthesized by the reaction of the related bidentate O, N-type Schiff base ligand and VO(acac)2 in the ratio of 2:1 in methanol in the reflux conditions. The Schiff base ligand and its vanadyl complex were characterized by 1H-NMR and FT-IR spectra and elemental analysis. The crystal structure of 1 was also determined the single-crystal X-ray analysis. It showed that the metal center located in a distorted tetragonal pyramidal (N2O3) geometry in which the two bidentate Schiff base ligands were coordinated to the vanadium(IV) ion in four equatorial positions, and one oxygen atom in its axial position. The catalytic activity of the vanadyl Schiff base complex was elucidated in the epoxidation of cyclooctene as a model substrate. Different reaction parameters were investigated in this reaction and the results showed that it was an effective and selective catalyst in these optimal conditions. Thermogravimetric analysis of 1 showed that it was decomposed in two stages by losing two methoxy groups and other organic residuals, respectively, in the temperature range of 253–532 °C. In addition, the vanadyl Schiff base complex (1) was thermally decomposed in air at 660 °C and the XRD pattern of the obtained solid showed the formation of the V2O5 nano-particles with the average size of 52 nm. 相似文献
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Dr. Raoul Blume Dr. Wolfram Calvet Dr. Aliakbar Ghafari Dr. Thomas Mayer Dr. Axel Knop-Gericke Prof. Dr. Robert Schlögl 《Chemphyschem》2023,24(23):e202300231
NiOx films on Si(111) were put in contact with oxygen at elevated temperatures. During heating and cooling in oxygen atmosphere Near Ambient Pressure (NAP)-XPS and -XAS and work function (WF) measurements reveal the creation and replenishing of oxygen vacancies in dependence of temperature. Oxygen vacancies manifest themselves as a distinct O1s feature at 528.9 eV on the low binding energy side of the main NiO peak as well as by a distinct deviation of the Ni2p3/2 spectral features from the typical NiO spectra. DFT calculations reveal that the presence of oxygen vacancies leads to a charge redistribution and altered bond lengths of the atoms surrounding the vacancies causing the observed spectral changes. Furthermore, we observed that a broadening of the lowest energy peak in the O K-edge spectra can be attributed to oxygen vacancies. In the presence of oxygen vacancies, the WF is lowered by 0.1 eV. 相似文献