Roughness of Crack Interfaces in Two-Dimensional Beam Lattices

The roughness of crack interfaces is reported in quasistatic fracture, using an elastic network of beams with random breaking thresholds. For strong disorders we obtain 0.86(3) for the roughness exponent, a result which is very different from the minimum energy surface exponent, i.e., the value 2/3. A cross-over to lower values is observed as the disorder is reduced, the exponent in these cases being strongly dependent on the disorder.Comment: 9 pages, RevTeX, 3 figure

Human peripheral blood lymphocytes as a cell model to evaluate the genotoxic effect of coal tar treatment

Peripheral blood lymphocytes (PBL) from psoriatic patients therapeutically exposed to polycyclic aromatic hydrocarbons (PAH) during coal tar (CT) treatment were used to evaluate the in vivo formation of benzo[a]pyrene diol epoxide(BaPDE)-DNA adducts by an ELISA technique and by the 32P-postlabeling method. Moreover, we controlled if the pretreatment with CT influences the formation of BaP-DNA adducts and the BaP metabolism in the PBL obtained from psoriatic patients, treated in vitro with BaP. Our data did not show any significant influence of the CT treatment on the levels of PAH-DNA adducts. Moreover, the use of PBL from psoriatic patients, treated in vitro with BaP, did not allow to detect significant modifications of the metabolic activation of BaP and of the ability of its metabolites to bind to DNA, before and after CT treatment. Thus, PBL do not seem to represent an useful cell model to evaluate the possible genotoxic effect of the exposure through the skin of psoriatic patients to the PAH contained in CT