The influence of localized damage in a sample on its resonance spectrum.

A nonlinear version of resonance ultrasound spectroscopy (RUS) theory is presented. This is important for NDT-purposes as damage manifests itself more pronounced and in an earlier stage by changes in the nonlinear elastic constants. General equations are derived for the 1-D case, describing the interaction between the modes due to the presence of nonlinearity.

Resonant bar simulations in media with localized damage.

As a rule, problems of wave propagation in finite media with non-uniform spatial distribution of material properties can only be tackled by numerical models. In addition, the modeling of damage features in a material requires the introduction of locally non-linear and--more important--non-unique equations of state. Using a multiscale approach, we have implemented a non-linear hysteretic stress-strain relation based on the Preisach-Mayergoyz (PM) model, into a numerical elastodynamic finite integration technique program, which has originally been developed for linearly elastic wave propagation in inhomogeneous media.

Antimicrobial peptides from scorpion venom induce Ca(2+) signaling in HL-60 cells.

Parabutoporin (PP) and opistoporin 1 (OP1) are amphipathic alpha-helical antimicrobial peptides that were recently isolated from scorpion venom. In assays in which single granulocyte-like HL-60 cells as well as cells in suspension were used, both peptides were able to induce a reversible Ca(2+) release from intracellular stores and to increase Ca(2+) influx. Both effects could be clearly differentiated for OP1, inducing Ca(2+) release at lower concentrations.