排序方式: 共有86条查询结果,搜索用时 812 毫秒
21.
Caroline Sperandio Claire Arnoult Abdelghani Laachachi Jean Di Martino David Ruch 《Micron (Oxford, England : 1993)》2010,41(2):105-111
The aim of this work is to introduce the use of low vacuum scanning electron microscopy (LVSEM) coupled with an X-ray energy dispersive spectrometer (EDS) in the field of structural adhesives, more precisely aluminium/epoxy resin assembly. Such assembly is characterized by the creation of an interphase resulting from the metal diffusion inside the resin during cross-linking. As the performance of the final bond is strongly links by the interphase properties, fine characterization of this interphase, in particularity the evaluation of its thickness is essential to understand the macroscopic properties of the adhesive assembly. First, the EDS acquisition parameters were investigated in order to limit the sample/resin damage/degradation due to the incident electrons beam irradiation. Then a specific methodology of stacked profiles was defined to improve the precision of the measures. To evaluate the true Al diffusion profile, the impact of the interaction volume of incident electron in the material on the Al signal variation during the interface crossing was calculated and the effect of the gas pressure on the electron beam characteristic and so on the measured profiles was examinated.According to our developed methodology and data treatments, Al diffusion profile was interpreted and interphase thickness was qualitatively determined by comparison with an experimental baseline. This innovative methodology promotes the use of LVSEM–EDS in the field of adhesive structural assemblies, but also, deals with a comparative study on the effect of the gas pressure on the EDS profile analysis. 相似文献
22.
Teggar Mohamed Laouer Abdelghani Arıcı Müslüm Ismail Kamal A. R. 《Journal of Thermal Analysis and Calorimetry》2022,147(21):11611-11632
Journal of Thermal Analysis and Calorimetry - Thermal resistance of ice slows down the charging/discharging process of ice storage systems which results in long operating cycles and thus high... 相似文献
23.
Mouna Hnaien Walid Mohamed Hassen Adnane Abdelghani Stéphane Cotte Didier Leonard François Bessueille Nicole Jaffrezic-Renault 《Electrochemistry communications》2009,11(1):165-168
A conductometric enzyme biosensor using proteinase K was developed and then tested to relate its electrical signal to the number of proteinase K hydrolysis sites in bovine serum albumin (BSA) and angiotensin, a ten amino acid peptide, with one cleaving site.The conductometric sensor presents a large linear range of response for BSA and angiotensin ranging from 0.5 to 8 mg/l and from 4 to 8 mg/l, respectively. For a same tested concentration (mg/l), the response for native BSA is 12 times higher than for angiotensin. Aspartam was used as negative test and no response was obtained with the proteinase K biosensor. The conductometric sensor permitted also to detect difference on enzyme activity on native and non-native BSA, a response three times higher was obtained for non-native BSA. 相似文献
24.
25.
Nicola Bellomo Abdelghani Bellouquid Juan Soler 《Mathematical and Computer Modelling》2009,49(11-12):2083-2093
This paper deals with the derivation of macroscopic equations from the underlying kinetic model delivered by the kinetic theory of active particles with discrete microscopic states. Hyperbolic models for local density and mean velocity are obtained with the aim at adding further knowledge to mathematical methods for modelling living matter. 相似文献
26.
Chiboub-Fellah Abdelghani Meullemeestre Jean Spies Catrin Vierling François Khan Mustayeen A. 《Transition Metal Chemistry》1999,24(2):135-140
Four NiII chloro complexes were identified spectrophotometrically in aprotic media such as DMSO, DMF and propylene carbonate for the first time. An original multiwavelength numerical treatment, based on a Marquardt method, results in the determination of the individual electronic spectra of the mononuclear chloro complexes and of their stability constants, the values of which indicate the presence of rather weak complexes in DMSO and DMF, much stronger in the less solvating propylene carbonate solvent. The overall stability constants calculated for the NiII chloro complexes are: 1=52, 2=140, 3=160, 4=210 in DMSO, 1=60, 2=110, 3=900, 4=15000 in DMF, 1=1.6×109, 2=6.4×1015, 3=2.7×1021, 4= 5.1×1026 in PC.The solvent effect is discussed in terms of the quantitative results obtained from this spectrophotometric study and reveals that the stability of the complexes is an inverse function of the donor properties of the solvent. This result illustrates the general behavior of complex formation in dipolar aprotic solvents, i.e. the substitution of one solvent molecule in the inner coordination sphere by the ligand is easier if the solvation strength of the solvent is lower. The solvent effect is also described in terms of the variation of shifts of the calculated absorption maxima for the individual electronic spectra of the chloro complexes. This result is used to identify clearly at which step of coordination the octahedral configuration of the nickel ion changes to the tetrahedral configuration, by comparison with the well-known structural properties of these complexes in the solid state. 相似文献
27.
Abdelghani Zeghib 《Mathematische Annalen》1998,310(4):695-716
This article deals with the structure of the fundamental group of compact anti de Sitter spacetimes, i.e. Lorentz manifolds
with constant negative curvature. Algebraically such a manifold is the quotient of the universal cover of the homogeneous
space by a discrete group acting properly and co-compactly on it. This exists if and only if is even. Indeed, as this was observed by Kulkarni, is contained in , and acts properly transitively on . It then suffices to take as a co-compact lattice in . The results of the present article give evidence to the question: in dimension , are all compact anti de Sitter spacetimes constructed in this way?
Received: 18 May 1996 / Revised version: 3 January 1997 相似文献
28.
Degenerate Riemannian metrics exist naturally in various contexts. Unfortunately, their study stops to the ‘admission of failure’ that they are too poor, for instance, to generate a coherent intrinsic or extrinsic differential geometry, e.g. a kind of Levi-Civita connection. In this first text, we start the investigation of rigidity aspects of these structures, from the point of view of isometric actions of ‘big’ (e.g. semi-simple) Lie groups. To cite this article: E. Bekkara et al., C. R. Acad. Sci. Paris, Ser. I 343 (2006). 相似文献
29.
Abdelghani Hajlane Hamid Kaddami Roberts Joffe Lennart Wallström 《Cellulose (London, England)》2013,20(6):2765-2778
This paper describes an approach to manufacture hierarchical composites from environmentally friendly materials by grafting cellulose whiskers onto regenerated cellulose fibers (Cordenka 700). Fourier Transform Infrared spectroscopy, Scanning Electron Microscopy and X-ray diffraction analysis were performed to verify the degree of modification. The mechanical properties of the unmodified and modified fibers were analyzed using fiber bundle tensile static and loading–unloading tests. To show the effect of cellulose whiskers grafting on the Cordenka fibers, epoxy based composites were manufactured and tensile tests done on transverse uni-directional specimens. The mechanical properties were significantly increased by fiber modification and addition of the nano-phase into composite reinforced with micro-sized fibers. 相似文献
30.
Blandine Friederich Abdelghani Laachachi Rodolphe Sonnier Michel Ferriol Marianne Cochez Valérie Toniazzo David Ruch 《先进技术聚合物》2012,23(10):1369-1380
A comparison of alumina (Al2O3) and boehmite (AlOOH) in (ammonium polyphosphate/melamine polyphosphate/metal oxide) ternary system was performed in poly(methyl methacrylate) on thermal and fire‐resistance properties. A Design of Experiments (DoE) was then done for highlighting the best formulation out of both ternary systems. Laser flash analysis and scanning electron microscopy helped to explain some of the observations made by DoE. Mechanisms in both ternary systems during degradation also were investigated and modes of action could be presented based on pyrolysis‐combustion flow calorimetry, Raman spectroscopy and X‐ray diffraction. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献