Recently discovered reactivity of nitrostyrenes in phosphorous acid to facilitate the diastereoselective [4 + 1]-cycloaddition of indoles in combination with unusual oxazoline ring cleavage and subsequent 1,2-alkyl shift afforded stereochemically defined 2-(3-oxoindolin-2-yl)-2-arylacetonitriles as sole products.
An
acid-assisted [4 + 1]-cycloaddition of indoles with nitrostyrenes
affords 4′H-spiro[indole-3,5′-isoxazoles]
in a diastereomerically pure form. Several of these spirocyclic molecules
exhibit promising anticancer activity by reducing viability and inducing
differentiation of neuroblastoma cells.
Experimental analyses of shrinkage and distortion kinetics during sintering of bilayered porous and dense gadolinium-doped ceria Ce 0.9 Gd 0.1 O 1.95Àd structures are carried out, and compared with the theoretical models developed in Part I of this work. A novel approach is developed for the determination of the shear viscosities ratio of the layer fully dense materials. This original technique enables the derivation of all the input parameters for the bilayer sintering modeling from one set of optical dilatometry measurements, including the conversion between real and specific times of sintering, the layers' relative sintering intensity, and the shear viscosities ratio of the layer fully dense materials. These optical dilatometry measurements are conducted simultaneously for each individual layer and for a symmetric trilayered porous structure based on the two layers utilized in the bilayered system. The obtained modeling predictions indicate satisfactory agreement with the results of sintering of a bilayered cerium-gadolinium oxide system in terms of distortion and shrinkage kinetics.
This paper reviews research articles published in the former USSR and post-soviet countries on the consolidation of powder materials using electric current that passes through the powder sample and/or a conductive die-punch set-up. Having been published in Russian, many of the reviewed papers are not included in the mainstream electronic databases of the scientific articles and thus are not known to the scientific community. The present review is aimed at filling this information gap. In the paper, the electric current-assisted sintering techniques based on high- and low-voltage approaches are presented. The main results of the theoretical modeling of the processes of electromagnetic field-assisted consolidation of powder materials are discussed. Sintering experiments and related equipment are described and the major experimental results are analyzed. Sintering conditions required to achieve the desired properties of the sintered materials are provided for selected material systems. Tooling materials used in the electric current-assisted consolidation set-ups are also described.
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