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71.
The liquid‐crystalline polymorphism of the homologous series of 4‐hexyloxybenzylidene‐4′‐alkyloxyanilines is investigated. Basing on the polarization microscopy (POM, TOA), the DSC calorimetry and miscibility studies the following mesophases were detected: nematic, smectic A, smectic C and smectic I. The phase diagrams of the compounds of these series with 4‐hexyloxybenylidene‐4′‐pentylaniline (as the standard of mesophases) show induction of the smectic F mesophases. Their dependence on the alkyl chain length and mole fraction is shown. 相似文献
72.
Rupali Vaid Monika Gupta Vivek K. Gupta 《Journal of the Iranian Chemical Society》2017,14(10):2199-2210
73.
Monika Dhariwal T. Maitra Ishwar Singh S. Koley A. Taraphder 《Solid State Communications》2012,152(20):1912-1916
The debate over the orbital order in the layered triangular lattice system NaTiO2 has been rekindled by the recent experiments of McQueen et al. [Phys. Rev. Lett. 101 (2008) 166402] on NaVO2. In view of this, the nature of orbital ordering, in both high and low temperature phases, is studied using an ab-initio electronic structure calculation. The orbital order observed in our calculations in the low temperature structure of NaTiO2 is consistent with the predictions of McQueen et al. An LDA plus dynamical mean-field calculation shows considerable transfer of spectral weight from the Fermi level but no metal–insulator transition, confirming the poor metallic behavior observed in transport measurements. 相似文献
74.
Argus Adrian Dunca Kara E. Kohler Monika Neda Leo G. Rebholz 《Mathematical Methods in the Applied Sciences》2012,35(10):1205-1219
This work presents a rigorous analysis of mathematical and physical properties for solutions of multiscale deconvolution turbulence models. We show that solutions of these models exactly conserve model quantities for the integral invariants of fundamental physical importance: kinetic energy, helicity, and (in two dimensions) enstrophy. The kinetic energy conservation is the key that allows us to next apply the phenomenology of homogeneous, isotropic turbulence to establish the existence of a model energy cascade and, in particular, that the cascade exhibits enhanced energy dissipation in a secondary accelerated cascade, which ends at the model's microscale (which we establish is larger than the Kolmogorov microscale). We also prove that the model dissipates energy at the same rate as true turbulent flow, ~ O(U3 ∕ L), independent of Reynolds number. Lastly, we prove the existence of global attractors for the model solutions; the proof of which also shows that solutions are actually one degree of regularity higher than previously known. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
75.
Regioselective formation of β‐(E)‐ and α‐alkenylsilane moiety attached to silsesquioxane core via Pt‐ and Ru‐based hydrosilylation 下载免费PDF全文
The first attempts to use ethynylsiloxysilsesquioxanes as reagents for hydrosilylation in the presence of Pt‐ and Ru‐based catalysts are reported. The results obtained strongly depend on the catalytic system used. The catalysts are proved to promote regioselective introduction of β‐(E)‐ and α‐fragments of the alkenylsilane group to the silsesquioxane core. The favourable features of these catalytic systems are their high selectivity and the requirement for relatively mild conditions. This methodology was also successfully applied to dihydro‐substituted organosilicon compounds to obtain a new class of silsesquioxane‐based compounds. 相似文献
76.
Back Cover: Large‐Scale Synthesis of Helicene‐Like Molecules for the Design of Enantiopure Thin Films with Strong Chiroptical Activity (Chem. Eur. J. 10/2016) 下载免费PDF全文
77.
A new class of stereoregular vinylene‐arylene copolymers with double‐decker silsesquioxane in the main chain 下载免费PDF全文
Michał Dutkiewicz Monika Ludwiczak Bogdan Marciniec Marek Nowicki 《Journal of polymer science. Part A, Polymer chemistry》2016,54(8):1044-1055
A synthesis of a new macromolecular class of vinylene‐arylene copolymers with double‐decker silsesquioxane in the main chain is presented. Two transition‐metal‐catalyzed processes, which is silylative‐coupling copolycondensation (SCC) and ADMET copolymerization of divinyl‐substituted double‐decker silsesquioxanes (DDSQ‐2SiVi) with selected diolefins, are reported to be highly efficient tools for the formation of stereoregular copolymers containing DDSQ‐silylene‐vinylene‐arylene units. The copolymeric products are studied in terms of their structural, thermal, and mechanical properties. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1044–1055 相似文献
78.
Large‐Scale Synthesis of Helicene‐Like Molecules for the Design of Enantiopure Thin Films with Strong Chiroptical Activity 下载免费PDF全文
Dr. Amina Bensalah‐Ledoux Delphine Pitrat Thibault Reynaldo Dr. Monika Srebro‐Hooper Barry Moore II Prof. Jochen Autschbach Dr. Jeanne Crassous Prof. Stéphan Guy Dr. Laure Guy 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(10):3333-3346
Helicenes are fascinating molecules owing to their unusual properties and applications in many fields from catalysis to organic electronics. Herein, we report a straightforward pathway for the synthesis of helicene‐like molecules on a gram scale in an enantiopure form. Thin‐film materials with good propagating optical properties and very high chiroptical responses have been grown by using pulsed laser ablation without altering the structure or the enantiopurity of the molecules. Moreover, electronic and vibrational circular dichroism spectroscopies coupled with theoretical calculations enabled some dependences of the chiroptical properties with the structure to be highlighted, for example, effects of rigidification, aromatization, or the state of matter (liquid versus solid). 相似文献
79.
Influence of the degree of ionization on the growth mechanism of poly(diallyldimethylammonium)/poly(acrylic acid) multilayers 下载免费PDF全文
Dörte Bütergerds Christian Kateloe Cornelia Cramer Monika Schönhoff 《Journal of Polymer Science.Polymer Physics》2017,55(5):425-434
pH‐dependent growth laws of the mass coverage Γ(n) of poly(diallyldimethylammonium) chloride and poly(acrylic acid) (PAA) layer‐by‐layer films are analyzed by Quartz Crystal Microbalance‐D. (Attenuated Total Reflection)‐FTIR spectroscopy shows a degree of dissociation of acrylic acid groups in the films identical to that in solution. Apart from pH‐regimes of differently pronounced exponential and linear growth, the corresponding kinetics indicate pH‐dependent adsorption, reorganization, and diffusion processes. As the thickest films form with almost uncharged PAA (low pH), the results can only partly be explained by the dissociation degree of PAA in the film. For intermediate and high pH values chain interdiffusion as a mechanism for nonlinear growth is strongly dependent on the charge density of the PAA chains. However, at low pH other types of interactions, most likely ion–dipole interactions, play a major role in the multilayer growth. Furthermore, a change in the symmetry of growth can be observed in the low to intermediate pH range. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 425–434 相似文献
80.