The effect of changes in grain size on corrosion resistance of the pure tough pitch copper stripwas investigated in acidic and alkaline NaCl solutions. Accumulative roll bonding as sever plastic process was applied up to 8 cycles to produce the ultrafine graincopper. Polarization and electrochemical impedance tests were used for corrosion resistance investigations. Corrosion morphologies were analyzed by FE-SEM. Results showed that the corrosion resistance decreased up to cycle 2 and increased after rolled for the fourth time due to UFG grain formation after cycle 4. The corrosion degradation in cycle 8 was uniformand it was more intergranular for the sample of cycle 2 and the unrolled counterpart.

An Euclidean graph associated with a molecule is defined by a weighted graph with adjacency matrix M = [d ij], where for i≠ j, d ij is the Euclidean distance between the nuclei i and j. In this matrix dii can be taken as zero if all the nuclei are equivalent. Otherwise, one may introduce different weights for distinct nuclei.In this paper, the automorphism group of the Bis Benzene Chromium(0) with D6d point group symmetry is computed. We also find an euclidean graph with an odd number of automorphisms. This solved a problem posed by the author in an earlier paper.

Un gráfico euclidiano asociado a una molécula es definido por un gráfico con matriz adyacente M = [d ij] donde i≠ j, d ij es la distancia euclidiana entre los nucleos i y j. En esta matriz dii puede ser tomada como cero si todos los núcleos son equivalentes. De otra manera, se pueden introducir diferentes pesos para distintos núcleos. En este trabajo se calcula el grupo de automorfismo del Bis Benceno Cromo(0) con simetría D6d. Se encontró también un gráfico euclidiano con un número impar de automorfismos. Este resultado resuelve un problema planteado por el autor en un artículo publicado previamente