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41.
Alexandre Gonçalves Dal Bó Yasmine Miguel Serafini Micheletto Fernando Carlos Giacomelli Georgina Lopez Maria Julia Recco Sartor Jamal Rafique 《Liquid crystals》2016,43(3):292-304
This article describes the synthesis and liquid crystal properties of new compounds that are derived from gallic acid. All the compounds were characterised by 1H and 13C nuclear magnetic resonance spectroscopy (1H NMR and 13C NMR), Infrared spectroscopy (IR) and Elemental analysis (CHN). The mesophases of these compounds were characterised using polarising optical microscopy (POM), differential scanning calorimetry (DSC) and SAXS measurements. The morphology of the surface of the films was investigated using atomic force microscopy (AFM). Compounds 9 and 13, which remain in a supercooled state until room temperature, do not exhibit liquid crystalline behaviour. The other compounds (i.e., 5, 7 and 8) self-assemble into tubular supramolecular architectures generating hexagonal columnar (Colh) mesophases, which was confirmed by SAXS measurements. 相似文献
42.
Stéphane Bouchonnet Sophie Bourcier Yasmine Souissi Christophe Genty Michel Sablier Pascal Roche Véronique Boireau Valérie Ingrand 《Journal of mass spectrometry : JMS》2012,47(4):439-452
The degradation of the chloracetamide herbicide acetochlor has been studied under simulated ozonation treatment plant conditions. The degradation of acetochlor included the formation of several degradation products that were identified using GC/ion‐trap mass spectrometry with EI and CI and HPLC/electrospray‐QqTOF mass spectrometry. Thirteen ozonation products of acetochlor have been identified. Ozonation of the deuterated herbicide combined to MSn and high‐resolution mass measurement allowed effective characterization of the degradation products. At the exception of one of them, the product B (2‐chloro‐2', ethyl‐6', methyl‐acetanilide), none of the identified degradation products has been already reported in the literature. Post‐ozonation kinetics studies revealed that the concentrations of most degradation products evolved noticeably with time, particularly during the first hours following the ozonation treatment. This raises concerns about the fate of degradation products in the effluents of treatment plants and suggests the need for a better control on these products if their toxicity was demonstrated. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
43.
Bouchonnet S Bourcier S Souissi Y Genty C Sablier M Roche P Boireau V Ingrand V 《Journal of mass spectrometry : JMS》2012,47(4):439-452
The degradation of the chloracetamide herbicide acetochlor has been studied under simulated ozonation treatment plant conditions. The degradation of acetochlor included the formation of several degradation products that were identified using GC/ion-trap mass spectrometry with EI and CI and HPLC/electrospray-QqTOF mass spectrometry. Thirteen ozonation products of acetochlor have been identified. Ozonation of the deuterated herbicide combined to MS(n) and high-resolution mass measurement allowed effective characterization of the degradation products. At the exception of one of them, the product B (2-chloro-2', ethyl-6', methyl-acetanilide), none of the identified degradation products has been already reported in the literature. Post-ozonation kinetics studies revealed that the concentrations of most degradation products evolved noticeably with time, particularly during the first hours following the ozonation treatment. This raises concerns about the fate of degradation products in the effluents of treatment plants and suggests the need for a better control on these products if their toxicity was demonstrated. 相似文献
44.
This paper describes a new numerical method for the solution of large linear discrete ill-posed problems, whose matrix is a Kronecker product. Problems of this kind arise, for instance, from the discretization of Fredholm integral equations of the first kind in two space-dimensions with a separable kernel. The available data (right-hand side) of many linear discrete ill-posed problems that arise in applications is contaminated by measurement errors. Straightforward solution of these problems generally is not meaningful because of severe error propagation. We discuss how to combine the truncated singular value decomposition (TSVD) with reduced rank vector extrapolation to determine computed approximate solutions that are fairly insensitive to the error in the data. Exploitation of the structure of the problem keeps the computational effort quite small. 相似文献
45.
We propose and study the use of convex constrained optimization techniques for solving large-scale Generalized Sylvester Equations
(GSE). For that, we adapt recently developed globalized variants of the projected gradient method to a convex constrained
least-squares approach for solving GSE. We demonstrate the effectiveness of our approach on two different applications. First,
we apply it to solve the GSE that appears after applying left and right preconditioning schemes to the linear problems associated
with the discretization of some partial differential equations. Second, we apply the new approach, combined with a Tikhonov
regularization term, to restore some blurred and highly noisy images. 相似文献
46.
In many problems of linear image restoration, the point spread function is assumed to be known even if this information is usually not available. In practice, both the blur matrix and the restored image should be performed from the observed noisy and blurred image. In this case, one talks about the blind image restoration. In this paper, we propose a method for blind image restoration by using convex constrained optimization techniques for solving large-scale ill-conditioned generalized Sylvester equations. The blur matrix is approximated by a Kronecker product of two matrices having Toeplitz and Hankel forms. The Kronecker product approximation is obtained from an estimation of the point spread function. Numerical examples are given to show the efficiency of our proposed method. 相似文献
47.
Detry JG Sindic M Servais MJ Adriaensen Y Derclaye S Deroanne C Rouxhet PG 《Journal of colloid and interface science》2011,355(1):210-221
The factors influencing the adherence of starch were examined to improve the understanding of the mechanisms affecting soiling and cleanability. Therefore an aqueous suspension of starch granules was sprayed on four model substrates (glass, stainless steel, polystyrene and PTFE) and dried, and the substrates were cleaned using a radial-flow cell. The morphology of the soiled surfaces and the substrate chemical composition were also characterized. By influencing droplet spreading and competition between granule-substrate and granule-granule interfaces regarding the action of capillary forces, substrate wettability affected the shape and compactness of the adhering aggregates, the efficiency of shear forces upon cleaning, and finally the adherence of soiling particles. The rate of drying had an influence explained by the duration left to capillary forces for acting. X-ray photoelectron spectroscopy demonstrated the presence of macromolecules, mainly polysaccharides, which were adsorbed from the liquid phase, or carried by the retracting water film and deposited at the granule-substrate interface. These macromolecules acted as an adhesive joint, the properties of which seemed to be influenced by the detailed history of drying and subsequent exposure to humidity. In summary, the substrate surface energy affects the adherence of starch aggregates by different mechanisms which are all linked together: suspension droplet spreading, action of capillary forces, direct interaction with starch particles and interfacial macromolecules. 相似文献
48.
We discuss multivariate interpolation with some radial basis function, called radial basis function under tension (RBFT). The RBFT depends on a positive parameter which provides a convenient way of controlling the behavior of the interpolating surface. We show that our RBFT is conditionally positive definite of order at least one and give a construction of the native space, namely a semi-Hilbert space with a semi-norm, minimized by such an interpolant. Error estimates are given in terms of this semi-norm and numerical examples illustrate the behavior of interpolating surfaces. 相似文献
49.
Yasmine B. Sanderson 《Journal of Algebraic Combinatorics》2000,11(3):269-275
We show that the specialization of nonsymmetric Macdonald polynomials at t = 0 are, up to multiplication by a simple factor, characters of Demazure modules for
. This connection furnishes Lie-theoretic proofs of the nonnegativity and monotonicity of Kostka polynomials. 相似文献
50.
Arabi Malika Elias Abdelhamid Kamel Ziane Ait younes Yasmine Mansouri Belkacem Toumert Idir 《Journal of Radioanalytical and Nuclear Chemistry》2018,317(2):1095-1106
Journal of Radioanalytical and Nuclear Chemistry - Gamma irradiation was applied to olive mill wastewater and synthetic samples prepared from Gallic acid. The effects, generated on the... 相似文献