Role of reaction atmosphere in preparation of potassium tantalate through sol–gel method

Potassium tantalate (KT) thin films and powders of both K₂Ta₂O₆ (KT pyrochlore) and KTaO₃ (KT perovskite) structures were prepared by means of chemical solution deposition method using Si(111) with ZnO and MgO buffer layers as a substrate. The influence of reaction atmosphere on reaction pathway and phase composition for both KT powders, and KT thin films has been studied mainly by means of powder diffraction and infrared spectroscopy. When an oxygen flow instead of static air atmosphere has been used the process of pyrolysis in oxygen runs over much narrower temperature interval (200–300 °C), relatively to air atmosphere (200–600 °C) and almost no (in case of powders), or no (in case of thin films) pyrochlore intermediate phase has been detected in comparison with treatment in air, where the pyrochlore phase is stable at temperatures 500–600 °C (powders). KT perovskite phase starts to crystallize at temperatures 50° and 150 °C lower compared to air atmosphere in case of powders and thin films, respectively. Microstructure formed by near-columnar grains and small grains of equiaxed shape was observed in films treated in oxygen and air atmosphere, respectively.     

New Reactions of N‐tert‐Butylimines; Formation of N‐Heterocycles by Methyl Radical Elimination on Flash Vacuum Thermolysis of N‐Benzylidene‐ and N‐(2‐Pyridylmethylidene)‐tert‐butylamines

Thermal reactions of N‐benzylidene‐ and N‐(2‐pyridylmethylidene)‐tert‐butylamines ( 5 and 13 ) under FVT conditions have been investigated. Unexpectedly, at 800 °C, compound 5 yields 1,2‐dimethylindole and 3‐methylisoquinoline. In the reaction of 13 at 800 °C, 3‐methylimidazo[1,5‐a]pyridine was obtained as the major product. Mechanisms of these reactions have been proposed on the basis of DFT calculations. Furthermore, UV‐photoelectron spectroscopy combined with FVT has been applied for direct monitoring and characterization of the thermolysis products in situ.     

A Supersymmetric AKNS Problem and Its Darboux‐Bäcklund Transformations and Discrete Systems

In this paper, we consider a supersymmetric AKNS spectral problem. Two elementary and a binary Darboux transformations are constructed. By means of reductions, Darboux and Bäcklund transformations are given for the supersymmetric modified Korteweg‐de Vries, sinh‐Gordon, and nonlinear Schrödinger equations. These Darboux and Bäcklund transformations are adopted for the constructions of integrable discrete super systems, and both semidiscrete and fully discrete systems are presented. Also, the continuum limits of the relevant discrete systems are worked out.     

On existence and multiplicity of similarity solutions to a nonlinear differential equation arising in magnetohydrodynamic Falkner–Skan flow for decelerated flows

Previously, existence and uniqueness of a class of monotone similarity solutions for a nonlinear differential equation arising in magnetohydrodynamic Falkner–Skan flow were considered in the case of accelerating flows. It was shown that a solution satisfying certain monotonicity properties exists and is unique for the case of accelerated flows and some decelerated flows. In this paper, we show that solutions to the problem can exist for decelerated flows even when the monotonicity conditions do not hold. In particular, these types of solutions have nonmonotone second derivatives and are, hence, a distinct type of solution from those studied previously. By virtue of this result, the present paper demonstrates the existence of an important type of solution for decelerated flows. Importantly, we show that multiple solutions can exist for the case of strongly decelerated flows, and this occurs because of the fact that the solutions do not satisfy the aforementioned monotonicity requirements. Copyright © 2015 John Wiley & Sons, Ltd.     

In search for chelating TAMLs (tetraamido macrocyclic ligands) with peripheral bidentate donor centers: a cobalt(III) complex of the 3,3′-(2,2′-bipyridindiyl)-tailed TAML

The synthesis of 1,2-C₆H₄(NHCOCMe₂NHCO)₂-3,3′-(2,2′-bpy) (3), a TAML (tetraamido macrocyclic ligand) incorporating the peripheral 2,2′-bipyridine unit, is described. Its geometry after optimization by density functional theory (DFT) indicated a rather unfavorable conformation of four N–H amide units for forming macrocyclic transition metal complexes. This explains why the iron(III) derivative of 3 could not be obtained even after deprotonation of the N–H bonds by n-BuLi. Nevertheless, the macrocyclic complex of Co^III was synthesized in moderate yield, characterized, and explored by DFT. Our data suggest a strongly distorted square-planar geometry of the macrocyclic complex between Co^III and 3. The dihedral angle between the pyridine rings equals 80° ruling out the possibility of metal chelation by the bipyridine unit.     

High dynamic range proteome imaging with the structured illumination gel imager

A current challenge for proteomics is detecting proteins over the large concentration ranges found in complex biological samples such as whole‐cell extracts. Currently, no unbiased, whole‐proteome analysis scheme is capable of detecting the full range of cellular proteins. This is due in part to the limited dynamic range of the detectors used to sense proteins or peptides. We present a new technology, structured illumination (SI) gel imager, which detects fluorescently labeled proteins in electrophoretic gels over a 1 000 000‐fold concentration range. SI uses computer‐generated masks to attenuate the illumination of highly abundant proteins, allowing for long exposures of low‐abundance proteins, thus avoiding detector saturation. A series of progressively masked gel images are assembled into a single, very high dynamic range image. We demonstrate that the SI imager can detect proteins over a concentration range of approximately 1 000 000‐fold, making it a useful tool for comprehensive, unbiased proteome‐wide surveys.     

Efficient access to fluorinated homoallylic alcohols through an indium promoted fluoroallylation reaction

Herein, an efficient access to fluorinated homoallylic alcohol is reported. The fluorinated alcohols were obtained in good to excellent yield using indium and halo-fluorinated allylic derivatives. The developed methodology using γ-substituted halo-fluorinated allylic derivatives gave the corresponding α-substituted fluorinated homoallylic alcohol in good yields and good diastereoselectivities up to 86:14.