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1.
Crystallography Reports - A new mixed-valence coordination polymer [Cu3(SCN)4(DMSO)2] n (SCN– = thiocyanato and DMSO = dimethyl sulfoxide) was prepared and characterized by single crystal... 相似文献
2.
Ines Walha 《Mathematical Methods in the Applied Sciences》2014,37(14):2135-2149
In this paper, we deal with the M‐essential spectra of unbounded linear operators in Banach spaces where some generalizations of earlier work are given. Furthermore, we give an application from transport theory. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
3.
This paper gives a survey on some recent results on the spectral theory of block operator matrices. We study the closeness in the product space and we give some conditions to characterize the essential spectra in the Browder resolvent set case. Furthermore, we apply the obtained results to several models such as delay equations, Sturm–Liouville problem and transport equations. 相似文献
4.
In this paper a new concept for a 3×3 block operator matrix is studied on a Banach space. It is shown that, under certain conditions, it defines a closable operator and its essential spectra are determined. Application to transport operators in L1-space is given. 相似文献
5.
Chemical preparation, X-ray single crystal diffraction, IR and NMR spectroscopic investigations of a novel nonlinear optical organic compound (C17H22NO2Cl) are described. The compound crystallizes in the orthorhombic system with the non-centrosymmetric sp. gr. P212121. In the crystal structure, molecules are interconnected by N–H…O hydrogen bonds forming infinite chains along a axis. The Hirshfeld surface and associated fingerprint plots of the compound are presented to explore the nature of intermolecular interactions and their relative contributions in building the solid-state architecture. The molecular HOMO–LUMO compositions and their respective energy gaps are also drawn to explain the activity of the compound. The first hyperpolarizability βtot of the title compound is determined using DFT calculations. The optical properties are also investigated by UV–Vis absorption spectrum. 相似文献
6.
Marwa Belghith Nedra Moalla Ines Walha 《Mathematical Methods in the Applied Sciences》2017,40(18):7218-7230
We define an abstract setting to treat essential spectra of unbounded coupled operator matrix. We prove a well‐posedness result and develop a spectral theory which also allows us to prove an amelioration to many earlier works. We point out that a concrete example from integro‐differential equation fit into this abstract framework involving a general class of regular operator in L1 spaces. 相似文献
7.
Nadia Belfguira Siwar Walha Abdelhamid Ben Salah Frédéric Hatert André Mathieu Fransolet Ahlem Kabadou 《Journal of chemical crystallography》2010,40(12):1125-1128
Abstract
Single crystals of iron and manganese phosphate Fe6.36Mn0.64(PO3(OH))4(PO4)2 was synthesized by hydrothermal method. The compound crystallizes in the Fe7(PO4)6 structure type and is isotypic with the solid solution \textM7 - \textx \textM\textx¢ ( \textHPO4 )4 ( \textPO4 )2 {\text{M}}_{{7 - {\text{x}}}} {\text{M}}_{\text{x}}^{\prime} \left( {{\text{HPO}}_{4} } \right)_{4} \left( {{\text{PO}}_{4} } \right)_{2} where M is Fe, Co, Mg, Mn. The compound is triclinic, P-1, a = 6.571(5), b = 7.993(3), c = 9.547(2) Ǻ, α = 103.97(1)°, β = 109.29(2)°, γ = 101.57(3)°. The structure is based on a three-dimensional framework of distorted edge-sharing MO6 and MO5 polyhedra, forming infinite chains, which are interlinked by corner-sharing with PO4 tetrahedra. The formula unit is centrosymmetric, with all atoms in general positions except for one Fe atom, which has site symmetry −1. 相似文献8.
Nadia Belfguira Siwar Walha Abdelhamid Ben Salah Andr Mathieu Fransolet Ahlem Kabadou 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(3):i33-i36
Single crystals of the solid solution iron aluminium tris(dihydrogenphosphate), (Fe0.81Al0.19)(H2PO4)3, have been prepared under hydrothermal conditions. The compound is a new monoclinic variety (γ‐form) of iron aluminium phosphate (Fe,Al)(H2PO4)3. The structure is based on a two‐dimensional framework of distorted corner‐sharing MO6 (M = Fe, Al) polyhedra sharing corners with PO4 tetrahedra. Strong hydrogen bonds between the OH groups of the H2PO4 tetrahedra and the O atoms help to consolidate the crystal structure. 相似文献
9.
Monia Hamdouni Lamya Agengui Siwar Walha Ahlem Kabadou Abdelhamid Ben Salah 《Journal of chemical crystallography》2011,41(11):1742-1750
Abstract
In the present study we report the synthesis, crystal structure, spectroscopic and thermal analysis of mixed alkali A1−x (NH4) x (H2C2O4)(HC2O4)(H2O)2 with A = K, Rb. Single crystal refinements showed that the two compounds Rb0.86(NH4)0.14(H2C2O4)(HC2O4)(H2O)2 and K0.53(NH4)0.47(H2C2O4)(HC2O4)(H2O)2 adopt P − 1 space group. The nine fold coordination cationic sites are randomly occupied by Rb+/NH4 + and K+/NH4 + respectively for rubidium and potassium compounds. The structure consists of a three-dimensional network formed by the succession along (c) axis of corrugated sheets formed by alkali polyhedra layers in the packing of four-membered rings [A4(HC2O4)2(H2C2O4)2] linked and bridged by oxalate groups that behave as bi and tetradentate ligand under three different coordination modes. The stability of the crystal lattice is ensured by interesting hydrogen bonding contacts: N–H···O and O–H···O. The thermal behavior under air reveals two anomalies at 368 and 402 K attributed respectively to a structural phase transition probably due to the reorientation of ammonium tetrahedral and to the release of crystalline water. IR spectroscopy further confirms that this material loses crystallization water gradually in the temperature range 400–460 K. 相似文献10.
Siwar Walha Mahmoud Bouchaala Abdelhamid Ben Salah 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(4):315-318
Mixed lithium/ammonium perchlorate, Li0.41(NH4)0.59ClO4, has been prepared by gel diffusion using agar agar gel as the medium of growth at ambient temperature. The Cl and mixed Li/N atoms are located on the 4a (, , ) and 4b (, 0, ) special positions, respectively, in the space group I2d. The structure features a twofold interpenetrated three‐dimensional entanglement architecture, in which single three‐dimensional networks are constructed from tetrahedral coordination based on [–(ClO4)–(Li/NH4)–(ClO4)–]∞ diamondoid arrays. A comparison of the crystal structures of Li0.41(NH4)0.59ClO4, LiClO4·3H2O, LiClO4 and NH4ClO4 is given. 相似文献