Perfect Plasticity Theory: State of the Art and Development Trends

The state of the art and development trends of model conceptions in perfect plasticity theory are overviewed. The paper does not consider limit equilibrium theorems, theory of optimum design and adaptability, flow problems in metal forming, dynamic behavior of rigid–plastic and elastic–plastic bodies, etc     

Solubility of Calcium Sulfate Dihydrate in Nitric Acid at 20°C

The solubility of gypsum in 0-30 wt % nitric acid solutions at 20°C was studied. The data were compared with the results obtained at 60°C.     

Experimental and Computational Studies on Cobalt(I)-Catalyzed Regioselective Allylic Alkylation Reactions

Here, we report the development of cobalt(I)-catalyzed regioselective allylic alkylation reactions of tertiary allyl carbonates with 1,3-dicarbonyl compounds. A family of well-defined tetrahedral cobalt(I) complexes bearing commercially available bidentate bis(phosphine) ligands [(P,P)Co(PPh₃)Cl] are synthesized and explored as catalysts in allylic alkylation reactions. The catalyst [(dppp)Co(PPh₃)Cl] (dppp=1,3-Bis(diphenylphosphino)propane) enables the alkylation of a large variety of tertiary allyl carbonates with high yields and excellent regioselectivity for the branched product. Remarkably, this methodology is selective for the activation of tertiary allyl carbonates even in the presence of secondary allyl carbonates. This contrasts with the selectivity observed in cobalt-catalyzed allylic alkylations enabled by visible light photocatalysis. Mechanistic insights by means of experimental and computational investigations support a Co(I)/Co(III) catalytic cycle.     

Kinetic characterization of strongly coupled systems

We propose a simple method to determine the local coupling strength Gamma experimentally, by linking the individual particle dynamics with the local density and crystal structure of a 2D plasma crystal. By measuring particle trajectories with high spatial and temporal resolution we obtain the first maps of Gamma and temperature at individual particle resolution. We employ numerical simulations to test this new method, and discuss the implications to characterize strongly coupled systems.     

General procedure for the synthesis of spirocyclic 3-hydroxy- and 3-oxotetrahydrofurans containing carboand heterocyclic fragments

Reactions of cyclopentanone, cyclohexanone, N-substituted pyrrolidin-3-one and piperidin-4-one, and tetrahydropyran-4-one with allyl bromide in the presence of zinc and ammonium chloride gave the corresponding geminal hydroxy allyl derivatives. Treatment of the latter with sodium periodate in the presence of sodium metabisulfite resulted in their oxidative cyclization with formation of oxa spirocyclic alcohols containing carbo- and heterocyclic fragments. Swern oxidation of the spiro alcohols afforded the corresponding ketones which were characterized as 2,4-dinitrophenylhydrazones.