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71.
Zacharias Amara 《Photochemistry and photobiology》2023,99(2):863-865
New molecular architectures with triplet sensitization properties can have a big impact on photochemistry and photobiology. In their recent work, de Bonfils et al. have tackled this challenge in a very systematic way using a powerful synthetic strategy. This consists of an elegant yet practical organocatalyzed cyclization/oxidation rearrangement sequence which they now apply to the synthesis of pyrroloquinolines, a new scaffold for photosensitizers. However, beyond this new class of compounds, the strategy has potential to produce a myriad of compact organic chromophores with promising photoinduced intersystem crossing properties. The study therefore provides interesting clues to serve the rational design of biocompatible molecular photosensitizers but also raises puzzling questions on the intriguing excited state reactivity of these molecular architectures. 相似文献
72.
The paper deals with the spectral and oscillatory properties of a linear operator pencilA ? λB, where the coefficient A corresponds to the differential expression (py″)″ and the coefficient B corresponds to the differential expression ?y″ + cry. In particular, it is shown that all negative eigenvalues of the pencil are simple and, under some additional conditions, the number of zeros of the corresponding eigenfunctions is related to the serial number of the corresponding eigenvalue. 相似文献
73.
74.
Hasna Jerbi Benoit Glorieux Alain Garcia Mongi Ben Amara 《Journal of solid state chemistry》2010,183(8):1752-1760
Two new isostructural rare earth phosphates Na7Mg13Ln(PO4)12 (Ln=La, Eu) have been synthesized and investigated by X-ray diffraction and optical measurements. They crystallize in the orthorhombic system with the Cmc21 space group (Z=4). The crystal structure exhibits a new type of framework built up from LnO8 (Ln=La, Eu), MO6 (M=0.5Mg+0.5Na) and MgOx (x=5, 6) polyhedra and PO4 tetrahedra linked by common corner, edge or face. It can be described in terms of [Mg4MP4O22]∞ layers stacked along the a direction. These layers are interconnected by [Mg4LnP4O36]∞ undulating chains spreading along the b direction. This framework delimits 6 distinct cavities occupied by Na+ cations. The results of the optical study of Na7Mg13La1−xEux(PO4)12 (x=0, 0.02, 0.1, 1) reveal the presence of two different Eu3+ ion environments whereas the X-ray study predicts the existence of only one Eu site. This difference can be explained by the possible presence of the europium element in the sodium sites with small occupancies which cannot be detected by the X-ray structural determination. 相似文献
75.
76.
Mohamed Amara Christine Bernardi Vivette Girault Frédéric Hecht 《Comptes Rendus Mathematique》2006,342(8):617-622
We consider the formulation of the Stokes problem in a multiply connected two-dimensional domain where the unknowns are the stream-function and the vorticity. We derive its equivalence with a finite system of several variational problems. This leads to the construction of a finite element discretization of this problem. The analysis and a numerical experiment prove the convergence of the method. To cite this article: M. Amara et al., C. R. Acad. Sci. Paris, Ser. I 342 (2006). 相似文献
77.
Abderrazek Karoui Amara Ammari Belgacem Selmi 《Journal of Fourier Analysis and Applications》2007,13(5):533-550
In this work, we study the existence of solutions of the deconvolution problems in the discrete setting. More precisely, we
prove the existence of solutions of the discrete multichannel deconvolution problems DMDP with convolvers being the characteristic
functions of finite sets of positive integers. Also, we provide the reader with a simple method and a fast algorithm for finding
the closed forms of the discrete deconvolvers with minimal supports that constitute exact solutions of the DMDP. Moreover,
we show that unlike the singular value decomposition scheme, the multichannel deconvolution scheme based on the use of these
discrete deconvolvers is not very sensitive to small 2-norm perturbation of the data. Finally, we show how to generalize our
method for solving the 2-D version of the DMDP. 相似文献
78.
Efficient capillary electrophoresis separation and determination of free amino acids in beer samples
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Miaomiao Tian Junfu Zhang Amara Camara Mohamed Yingzi Han Liping Guo Li Yang 《Electrophoresis》2014,35(4):577-584
Simultaneous detection of various o‐phthalaldehyde (OPA)‐labeled amino acids (AAs) in food samples was reported based on CE separation. Ionic liquid was used for the first time for CE analysis of AAs with in‐capillary derivatization. Several other additives, including SDS, α/β‐CD, and ACN, as well as key parameters for CE separation (buffer pH value, separation voltage), were also investigated. Our results show that the multiple additive strategy exhibits good stable and repeatable character for CE analysis of OPA‐labeled AAs, for either in‐capillary derivatization or CE separation, and allows simultaneous quantification of different OPA‐labeled AAs in a large concentration range of 50 μM to 3.0 mM with LOD down to 10 μM. Seventeen OPA‐labeled AAs, except for two pairs of AAs (His/Gln and Phe/Leu), which were separated with resolutions of 1.1 and 1.2, respectively, were baseline separated and identified within 23 min using the present multiple additive strategy. The method was successfully applied for simultaneous analysis of AAs in seven beer samples and as many as eleven trace‐amount AAs were detected and quantified, indicating the valuable potential application of the present method for food analysis. 相似文献
79.
The removal and separation of Cu(II), Zn(II) and Ni(II) from nitrate aqueous solutions were studied by competitive transport across cellulose triacetate plasticized membranes modified with polyelectrolytes: polyethyleneimine (PEI) and polyethyleneglycol (PEG). Competitive transport of trace ions from aqueous solutions across polymer inclusion membranes containing a mixture of the three polymers (cellulose triacetate as the support) and tris(2-ethylhexyl-phosphate) (TEHP) as the plasticizer provide the selectivity order: Cu(II) > Ni(II) > Zn(II). A long-term transport experiment was carried out to demonstrate the durability of polymer inclusion membranes. A separation of bivalents cations (Cu2+, Ni2+, Zn2+) and monovalent cations (K+ and Na+) is achieved. 相似文献
80.
Mohamed Amine Djebbi Saber Boubakri Mohamed Braiek Nicole Jaffrezic‐Renault Philippe Namour Abdesslem Ben Haj Amara 《Electroanalysis》2020,32(6):1186-1197
Nanocomposite of nanoscale zero‐valent iron (nZVI) and layered double hydroxide (LDH) was used as modifier for boron‐doped diamond electrode in determination of anti‐psychotic drug chlorpromazine (CPZ). nZVI nanoparticles were prepared by liquid phase reduction of ferric chloride with sodium borohydride on the surface of NiAl LDH matrix owing to the strong exchange and confinement efficiency of LDH. The structure, binding and surface properties of the nZVI@LDH nanocomposite were monitored using powder X‐ray diffractometry, FT‐IR spectroscopy, scanning and transmission microscopy and BET techniques. The electrochemical properties of the modified electrode were investigated by CV and EIS, performed in a phosphate buffer containing ferro/ferricyanide as redox probe. The modified electrode exhibited excellent electrochemical performance compared with unmodified electrode. As regard potential application of the nanocomposite surface to the CPZ detection, square‐wave voltammetric signals showed a good linear correlation over CPZ concentrations in a broad range from 0.1 to 8.0 μM with low detection limit of 0.005 μM. Nevertheless, these results suggest that the proposed nanocomposite modifier surface provides exceptional synergy and significant enhancement effect to the voltammetric response of CPZ and thus could be applied as highly efficient and stable platform of sensors in clinical analysis. 相似文献