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101.
Barberon F Baroghel-Bouny V Zanni H Bresson B d'Espinose de la Caillerie JB Malosse L Gan Z 《Magnetic resonance imaging》2005,23(2):267-272
The durability of cement-based materials with respect to exterior aggressions is one of the current priorities in civil engineering. Depending on their use, the cement-based materials can be exposed to different types of aggressive environments. For instance, damages to concrete structures in contact with a saline environment (sea water on bridges, deicing salts on roads, etc.) are of utmost importance. Upon exposure to saline water, Cl- ions penetrate into the structures and subsequently lead to reinforcement corrosion. Chloride attack is often combined with other aggressive influences such as temperature (e.g., freezing) or the ingress of other ions (e.g., sulfates in sea water). We therefore aim to explore the effect of sodium chloride (NaCl) on the structural chemistry of cement paste. Existing studies about reinforcement corrosion by chloride have focused on the penetration of Cl- ions and the comparison between "free" ions (water-soluble ions) and bound ones. However, little is known about the fixation mechanisms, the localization of Cl in the cement matrix and the structural interaction between Cl and the silicate and aluminate hydrate phases present in cement paste. We present here results of a multinuclear nuclear magnetic resonance study on the fixation of chloride in the hydration products and the characterization of new phases potentially appearing due to chloride ingress. 相似文献
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Dr. Silvia Voci Prof. Jean-Baptiste Verlhac Dr. Federico Polo Guillaume Clermont Dr. Jonathan Daniel Prof. Frédéric Castet Dr. Mireille Blanchard-Desce Prof. Neso Sojic 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(38):8407-8416
We synthesized and characterized a series of dyes built from a spirofluorene or truxene core. The quadrupolar spirofluorene system is the initial building unit for the design and preparation of more complex star-shaped dyes consisting of a truxene core bearing three di- or triphenylamine moieties with or without a thiophene connector. Their photophysical, electrochemical, and electrochemiluminescence (ECL) properties were first investigated in solution. Structure/activity relationships were derived and rationalized by comparing the quadrupolar system and trigonal truxene-core derivatives using computational studies. The photophysical and redox characteristics are drastically tuned by the introduction of a thiophene bridge and electron-donor substituents at their terminal branches. These comparative studies show the essential role of the stability of both radical cations and anions to obtain efficient ECL dyes. The stabilization of the radicals is directly related to the charge delocalization due to the π-conjugation by the thiophene bridge. The brightest ECL is achieved by annihilation and coreactant (benzoyl peroxide) pathways with the blue-emitting truxene dye, which is 2- and 4.5-times greater than that of the quadrupolar compound and reference [Ru(bpy)3]2+ emitter, respectively. Such an extensive study on these extended π-conjugated molecules presenting different core structures may guide the design and synthesis of new ECL dyes with a strong efficiency. 相似文献
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We derive an original direct imaging method of an object. It is based on topological derivatives, and aims at inverting the amplitude of waves that are retropropagated after laser illuminations. 相似文献
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Damien Polet Xavier Rathgeb Caroline A. Falciola Jean-Baptiste Langlois Samir El Hajjaji Alexandre Alexakis Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(5):1205-1216
We describe herein the development of the first iridium-catalyzed allylic substitution using arylzinc nucleophiles. High enantioselectivities were obtained from the reactions, which used commercially available Grignard reagents as the starting materials. This methodology was also shown to be compatible with halogen/metal exchange reactions. Its synthetic potential is demonstrated by its application towards the formal synthesis of (+)-sertraline. 相似文献
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Roni Ginzburg-Turgeman Jean-Baptiste Guion Daniel Mandler 《Journal of Solid State Electrochemistry》2011,15(11-12):2401-2407
Indium tin oxide (ITO) is the most commonly used transparent conducting substance. It has been used in numerous applications such as light-emitting diodes. In most applications and studies, the ITO surface is further coated with additional layers. The interface between the ITO and the coating is of utmost importance since it affects the physical and chemical properties of the final device. Improving the adhesion between ITO and a coating layer can be achieved by applying a ??molecular adhesive?? as an inter-phasing molecular layer. In this study, we used 3-(trimethoxysilyl)propyl methacrylate as a ??molecule adhesive?? for better connection between ITO and a polymethacrylate layer. The samples were studied by electrochemistry, contact angle goniometry, atomic force microscopy, and nano scratch microscopy. These studies clearly show that a simple silanization process formed a thin molecular adhesive layer, which did not influence the physical and chemical properties of the final coated electrode and at the same time increased significantly the adhesion between the ITO and the polymethacrylate coating. 相似文献
110.
A simple test is proposed for examining the correctness of a given completely specified response function against unspecified general alternatives in the context of univariate regression. The usual diagnostic tools based on residual plots are useful but heuristic. We introduce a formal statistical test supplementing the graphical analysis. Technically, the test statistic is the maximum length of the sequences of ordered (with respect to the covariate) observations that are consecutively overestimated or underestimated by the candidate regression function. Note that the testing procedure can cope with heteroscedastic errors and no replicates. Recursive formulae allowing one to calculate the exact distribution of the test statistic under the null hypothesis and under a class of alternative hypotheses are given. 相似文献