Strain hardening during constrained deformation of metal foams - Effect of shear displacement

The crush bands that form during plastic deformation of closed-cell metal foams are often inclined at 11-20 degrees to the loading axis, allowing for shear displacement of one part of the foam with respect to the other. Such displacement is prevented by the presence of a lateral constraint. This was analysed in this study, which shows that resistance against shear by the constraint leads to the strain-hardening effect in the foam that has been reported in a recent experimental study. (C) 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Rudolf Simonis working at desk; Albert Bonniers Foerlag; Stockholm Portraits Men

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Students of Willy Marckwald working in laboratory; Friedrich-Wilhelms-Universitaet Berlin Institutions; Universities

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Students of Willy Marckwald working in laboratory; Friedrich-Wilhelms-Universitaet Berlin Institutions; Universities

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Students of Willy Marckwald working in laboratory; Friedrich-Wilhelms-Universitaet Berlin Institutions; Universities

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Students of Willy Marckwald working in laboratory; Friedrich-Wilhelms-Universitaet Berlin Institutions; Universities

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Students of Willy Marckwald working in laboratory; Friedrich-Wilhelms-Universitaet Berlin Institutions; Universities

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Students of Willy Marckwald working in laboratory; Friedrich-Wilhelms-Universitaet Berlin Institutions; Universities

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Students of Willy Marckwald working in laboratory; Friedrich-Wilhelms-Universitaet Berlin Institutions; Universities

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Students of Willy Marckwald working in laboratory; Friedrich-Wilhelms-Universitaet Berlin Institutions; Universities

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Students of Willy Marckwald working in laboratory; Friedrich-Wilhelms-Universitaet Berlin Institutions; Universities

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Students of Willy Marckwald working in laboratory; Friedrich-Wilhelms-Universitaet Berlin Institutions; Universities

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Students of Willy Marckwald working in laboratory; Friedrich-Wilhelms-Universitaet Berlin Institutions; Universities

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Studies in metal-ammonia reduction. Part 4. Reduction and reductive methylation of 7-methoxy-3,4-dihydrophenanthren-1(2H)-one and 7-methoxy-1,2-dihydrophenanthren-4(3H)-one

Birch reduction and reductive methylations of the title compounds have been investigated. 7-Methoxy-3,4-dihydrophenanthren-1(2H)-one (2) yields the cis-3,4,9,10,11,12-hexahydro-derivative (15) while the 7-methoxy-1,2-dihydrophenanthren-4(3H)-one (5) is reduced to the corresponding 1,2,9,10-tetrahydro-derivative (7). The factors influencing the mechanism of the reduction process have been discussed. The reductive methylation products of the ketone (2) are useful substrates in the synthesis of 9-methyl steroids.

ESR study of metal ion-guanosine monophosphate interaction

The addition of guanosine 5-monophosphate (5′-GMP) to an aqueous solution of Mn2+ ions results in a decrease in ESR signal intensity and an increase in line-width of Mn2+ ions. This can be interpreted in terms of stepwise formation of outersphere and inner-sphere complexes as When Mg2+ is added to a mixture of Mn2+ and 5′-GMP, ESR signal intensity increases, presumably due to the replacement of Mn2+ by Mg2+ in the complex. From the variation of ESR signal intensity as a function of concentration of Mg2+, the product K1K2 for the magnesium complex i s calculated as 125 M−1. This difference in stability constants may indicate that both phosphate group and guanine base are involved in the formation of Mn2+-5′-GMP complex.