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61.
Basem Fares Ali Rawhi Al-Far Salim F. Haddad 《Journal of chemical crystallography》2010,40(8):696-701
Abstract
In the crystal structures of (2,6-lutidinium)2[CuCl4], 1 and (2,6-lutidinium)2[CuBr4], 2, the anion CuX4 2− is connected to eight and four surrounding cations in 1 and 2, respectively, through (N–H···X) (H2C–H···X) and (C–H···X) hydrogen bonds to form two-dimensional layers approximately normal to the crystallographic b-axis. These layers are further connected by means of offset face-to-face interactions (parallel to b-axis) to give three-dimensional structures. The hydrogen bonding (type and number) around each anion could be influenced by the anion size, as same cation is used, allowing different cation…anion interpenetrations. 相似文献62.
Volpe G Fares G delli Quadri F Draisci R Ferretti G Marchiafava C Moscone D Palleschi G 《Analytica chimica acta》2006,572(1):11-16
This paper reports the assembly of a disposable immunosensor based on the direct competitive enzyme-linked immunosorbent assay (ELISA), for simple and fast measurement of 17β-estradiol (17β-E2) in bovine serum, using screen-printed electrodes (SPEs) and a Palm-Sens portable electrochemical detector. The immunosensor strip was assembled immobilising, by passive adsorption, anti-rabbit IgG onto the surface of the working SPE electrode. After the interaction between anti-rabbit IgG and rabbit anti-17β-E2 polyclonal antibodies (PAb), the competition was performed using 17β-estradiol-alkaline phosphatase conjugate (17β-E2-AP) synthesised in our laboratory. The enzymatic substrate used for signal generation was 1-naphthylphosphate and its conversion to an electroactive product (1-naphthol) was measured using differential pulse voltammetry (DPV). To develop a prototype for field measurements, the entire competitive protocol has been optimised directly in a blank non-extracted bovine serum.According to the new EU criteria established by the Commission Decision 2002/657/EC for qualitative and quantitative screening methods, the detection capability (CCβ), was determined. The CCβ value resulted below the action limit (40 pg mL−1) fixed for 17β-E2.Spiked and real samples were analysed using the electrochemical immunostrips obtaining precision values (relative standard deviation, R.S.D.%) ranging from 8.6 to 17.0% and a recovery (R%) from 88.2 to 120.0%.Results obtained on real samples were confirmed by liquid chromatography coupled on-line with tandem mass spectrometry (LC-MS/MS) using an atmospheric pressure chemical ionisation (APCI) source and a heated nebulizer (HN) interface; this is the method currently used to confirm illegal hormone administration for regulatory purposes. The disposable immunosensor appears suitable as a screening tool for field analysis of bovine serum estradiol. 相似文献
63.
Fares Maalouf 《Journal of Pure and Applied Algebra》2018,222(5):1003-1005
We show that if k is an infinite field, then there exists a subspace of dimension , such that no nonzero member of W has infinitely many zeros. This generalizes a result from a paper by Bergman and Nahlus, and partly answers another question from the same paper. 相似文献
64.
Hichem Khelifi & Fares Mokhtari 《偏微分方程(英文版)》2020,33(1):1-16
This paper is devoted to the study of a nonlinear anisotropic
elliptic equation with degenerate coercivity, lower order term and L1 datum in appropriate
anisotropic variable exponents Sobolev spaces. We obtain the existence of distributional solutions. 相似文献
65.
In this article, we propose a quantum regime for Cherenkov free-electron laser (CFEL) and surface plasmon polaritons (SPPs) excited in dielectric and multilayer graphene waveguides, respectively. This quantum regime is realized when the momentum spread induced in the interaction is smaller than the photon recoil. The discrete momentum exchange characterizing this interaction yields a significantly narrow single emission line. To determine the condition of the quantum regime, we derive an expression for the gain in the Cherenkov effect using a quantum mechanical treatment. It is assumed that the effective spread in momentum is due to the finite interaction length L (or the propagation length in the case of SPPs). For both cases, CFEL and SPPs, the effects of electron beam and waveguide parameters on the possibility of the quantum regime are studied. We conclude that the quantum regime can be basically verified at low electron beam energy (<40 keV) and at emission wavelengths in the near infrared range (<5 μm) when L is in the order of millimeters. In the case of SPPs, we also show that the feasibility to realize quantum SPPs is enhanced by increasing the chemical potential and number of graphene layers. 相似文献
66.
We show that a polymer tip, integrated by free-radical photopolymerization at the end of a telecommunication optical fiber, allows high-efficiency coupling between the fiber and an infrared laser diode. A coupling efficiency of 70% (1.5-dB loss) was achieved. We obtained this result by controlling the radius of curvature of the tip, the origin of which is discussed in terms of the photochemical influence of oxygen during tip formation. The experimental data were found to be in agreement with results of electromagnetic calculations based on the finite-element method. 相似文献
67.
Among the methods that may be used to carry out multicenter integrals over STOS, the one-center two-range expansion is probably the oldest one. However, the convergence of the leading series is generally slow and, hence, time-consuming. Therefore, it was the aim of the present work to show that the so-called nonlinear sequence transformations may be of substantial help for improving the rate of convergence of such series. © 1994 John Wiley & Sons, Inc. 相似文献
68.
Hijazi Abu Ali Suhad N. Omar Mohanad D. Darawsheh Hadeel Fares 《Journal of Coordination Chemistry》2016,69(6):1110-1122
Metal carboxylate complexes possess different carboxylate coordination modes, e.g. monodentate, bidentate, and bridging bidentate. Five Zn(II) complexes were prepared and characterized in order to examine their coordination modes in addition to their biological activity. The syntheses were started by preparation of [Zn(ibup)2(H2O)2] (1). Then, different nitrogen-donor ligands reacted with 1 to produce [Zn(ibup)2(2-ampy)2] (2), [Zn(ibup)(2-ammethylpy)] (3), [Zn(ibup)(2,2′-bipy)] (4), and [Zn2(ibup)4(2-methylampy)2] (5) (ibup = ibuprofen, 2-ampy = 2-aminopyridine, 2-ammethylpy = 2-aminomethylpyridine, 2,2′-bipy = 2,2′-bipyridine, 2-methylampy = 2-(methylamino)pyridine). IR, 1H NMR, 13C{1H}-NMR and UV–vis spectroscopies were used for characterization. The crystal structures of 2 and 5 were determined by single-crystal X-ray diffraction. Investigation of in vitro antibacterial activities for the complexes against Gram-positive (Micrococcus luteus, Staphylococcus aureus and Bacillus subtilis) and Gram-negative (Escherichia coli, Klebsiella pneumoniae and Proteus mirabilis) bacteria were done using agar well-diffusion method. Complex 1 showed antibacterial activity against Gram-positive bacteria. Complexes 2 and 3 did not exhibit antibacterial activity. Complex 4 showed antibacterial activity and was chosen for further studies to determine the inhibition zone diameter for different concentrations and to set the minimum inhibitory concentration. The antibacterial activity against most of the bacteria was minimized as a result of the complexation of zinc ibuprofen with 2,2′-bipy in 4. 相似文献
69.
Francesca R CibinNicoletta Di Bello Giancarlo Doddi Vincenzo Fares Paolo Mencarelli Elio Ullucci 《Tetrahedron》2003,59(50):9971-9978
The intramolecular photocycloaddition of chalcones to give cyclobutanes has proved to be a fast and convenient method to shrink a cyclophane ring to a tricyclic system, in order to prepare potential ditopic receptors. X-Ray results confirm the previously indicated structure for the cyclobutanes 2a (n=1, m=1), in which the cyclization occurs by a head-to-head syn ring closure. NMR results indicate that the same process occurs for the cyclobutanes 2b (n=2, m=2) and 2c (n=1, m=3). 相似文献
70.