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381.
Armand Soldera Jean-François Nicoud Yves Galerne Antoine Skoulios Daniel Guillon 《Liquid crystals》2013,40(2):347-353
Abstract The synthesis and the properties of new ferroelectric liquid-crystalline compounds with a tolane rigid core and an optically active alkyl sulphinate group are reported. These compounds contain two chiral centres: a sulphinate group and a branched aliphatic chain. The two pure diastereomers having opposite configurations on the sulphur have been isolated. The mesomorphic behaviour of these two compounds is different, only one exhibiting an enantiotropic chiral smectic C phase; this clearly demonstrates the role of the sulphur configuration in determining the thermotropic properties. The mesomorphic transition temperatures, the structural behaviour as a function of temperature and preliminary measurements of the spontaneous polarization are presented. 相似文献
382.
New mesogens are always a source of interest, especially when they possess a non‐conventional architecture. In this article are presented the synthesis and polymorphism of a series of compounds possessing a 1,4‐diaryl‐1‐buten‐3‐yne moiety as the rigid core with an alkoxy chain on each side. Such a core is termed an enyne core. The alkoxy chain is lengthened on each side of the enyne core according to two different fashions: symmetrically and asymmetrically. In this way a rich polymorphism is achieved in some compounds. At lower chain length, the compounds exhibit smectic H and nematic phases where cybotactic groups are observed in X‐ray diffraction patterns. As the alkoxy chains extend, smectic C and smectic F phases appear. The non‐cylindrical shape of these compounds involves a molecular packing that is preserved throughout the polymorphism. A comparison between symmetric and asymmetric compounds, from X‐ray diffraction pattern analysis of their smectic H phases, reveals a parallel molecular stacking. It also discloses the importance of the moiety that is lengthened since different polymorphisms are obtained. 相似文献
383.
A. S. Shaplov D. O. Ponkratov P. S. Vlasov E. I. Lozinskaya L. I. Komarova I. A. Malyshkina F. Vidal G. T. M. Nguyen M. Armand C. Wandrey Ya. S. Vygodskii 《Polymer Science Series B》2013,55(3-4):122-138
A number of methacrylate ionic monomers with different structures and mobilities of ionic centers were synthesized. The free-radical polymerization of these monomers in solution affords high-molecular-mass (M sD = 0.5 to 2.5 × 106) thermally stable (T dec > 170°C) polyelectrolytes or cationic or anionic “polymeric ionic liquids.” The conductivities of polycation- and polyanion-derived coatings are (7.4 × 10?10)?(7.6 × 10?7) and (4.9 × 10?10)-(1.6 × 10?7) S/cm (25°C), respectively. As exemplified by poly(1-[3-(methacryloyloxy)propyl]-3-methylimidazolium bis[(trifluoromethanesulfonyl)imide]), the molecular mass and glasstransition temperature of the polymer affect the ionic conductivity of the film coating. The transition from linear polyelectrolytes to crosslinked systems based on ionic monomers and poly(ethylene glycol dimethacrylate) 750 leads to the formation of elastic films featuring satisfactory strength, reduced glass-transition temperatures (?8 to +15°C), and increased ionic conductivity (up to 3.2 × 10?6 S/cm (25°C)). 相似文献
384.
Kazi Akikur Rahman Tadeusz Bak Armand Atanacio Mihail Ionescu Janusz Nowotny 《Ionics》2018,24(2):309-325
The present chain of five papers considers the concept of defect engineering in processing TiO2-based photosensitive semiconductors for solar-to-chemical energy conversion. The papers report the effect of chromium on the key performance-related properties of polycrystalline TiO2 (rutile), including (i) electronic structure, (ii) chromium-related photocatalytic properties, (iii) oxygen-related photocatalytic properties, (iv) electrochemical coupling and (v) surface versus bulk properties. The present work reports the effect of chromium on defect disorder and the related electronic structure of TiO2, including the band gap and mid-gap energy levels. It is shown that chromium incorporation into the TiO2 lattice results in a decrease of the band gap from 3.04 eV for pure TiO2 to 1.4 and 1.3 eV, for Cr-doped TiO2 (1.365 at% Cr) after annealing at 1373 K in the gas phase of controlled oxygen activity, 21 kPa and 10?10 Pa, respectively. The optical properties determined using the ultraviolet-vis spectroscopy (in the reflectance mode) indicate that chromium incorporation results in the formation of mid-band energy levels. In this work, we show that chromium at and above the concentrations levels of 0.04 and 0.376 at% results in the formation of acceptor-type energy levels at 0.57 and 1.16 eV (above the valence band), respectively, which are related to tri-valent chromium in titanium sites and titanium vacancies, respectively. Application of well-defined protocol leads to the determination of data that are well reproducible. The new insight involves the determination of the band gap of TiO2 processed in the gas phase of controlled oxygen activity. 相似文献
385.
Kasprzyk-Kucewicz Teresa Cholewka Armand Bałamut Karolina Kownacki Patryk Kaszuba Natalia Kaszuba Michał Stanek Agata Sieroń Karolina Stransky Jiri Pasz Adam Morawiec Tadeusz 《Journal of Thermal Analysis and Calorimetry》2021,143(1):139-150
Journal of Thermal Analysis and Calorimetry - Coal has played a significant role in daily life. However, the highly effective combustion and reducing combustion-caused hazards of the coal still... 相似文献
386.
Antoine Rousseau Dr. Sylvie Armand Prof. Sylvain Cottaz Dr. Sébastien Fort 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(70):17637-17646
Chitin and peptidoglycan fragments are well recognized as pathogen associated molecular patterns (PAMPs). Long-chain oligosaccharides of β(1→4)-linked N-acetyl-D-glucosamine (GlcNAc) units indeed activate plants and mammals innate immune system. However, the mechanisms underlying PAMPs perception by lysine motif (LysM) domain receptors remain largely unknown because of insufficient availability of high-affinity molecular probes. Here, we report a two-enzyme cascade to synthesize long-chain β(1→4)-linked GlcNAc oligomers. Expression of the D52S mutant of hen egg-white lysozyme (HEWL) in Pichia pastoris at 52 mg L−1 provided a new glycosynthase catalyzing efficient polymerization of α-chitintriosyl fluoride. Selective N-deacetylation at the non-reducing unit of the glycosyl fluoride donor by Sinorhizobium meliloti NodB chitin-N-deacetylase abolished its ability to be polymerized by the glycosynthase but not to be transferred onto an acceptor. Using NodB and D52S HEWL in a one-pot cascade reaction allowed the synthesis on a milligram scale of chitin hexa-, hepta- and octasaccharides with yields up to 65 % and a perfect control over their size. 相似文献
387.
Armand Müller 《Fresenius' Journal of Analytical Chemistry》1873,12(1):117-118
Ohne Zusammenfassung 相似文献
388.
Armand Bertrand 《Fresenius' Journal of Analytical Chemistry》1881,20(1):109-110
Ohne Zusammenfassung 相似文献
389.
Armand de Waele 《Fresenius' Journal of Analytical Chemistry》1916,55(5-6):285
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