An embedded-atom-method (EAM) interatomic potential [1] for bcc-iron is derived. It is fitted exactly to the lattice parameter, elastic constants, an approximation to the unrelaxed vacancy formation energy, and Rose's expression for the cohesive energy [2]. Formation energies and relaxation volumes of point defects are calculated. We find that the relative energies of the defect configurations depend on the functional fitting details of the potential considered, mainly its range: the experimental interstitial configuration of lowest energy can be reproduced by changing this parameter. This result is confirmed by calculating the same defect energies using other EAM potentials, based on the ones developed by Harrison et al. [3].

Up to date, tissue regeneration of large bone defects is a clinical challenge under exhaustive study. Nowadays, the most common clinical solutions concerning bone regeneration involve systems based on human or bovine tissues, which suffer from drawbacks like antigenicity, complex processing, low osteoinductivity, rapid resorption and minimal acceleration of tissue regeneration. This work thus addresses the development of nanofibrous synthetic scaffolds of polycaprolactone (PCL)-a long-term degradation polyester-compounded with hydroxyapatite (HA) and variable concentrations of ZnO as alternative solutions for accelerated bone tissue regeneration in applications requiring mid-and long-term resorption. In vitro cell response of human fetal osteoblasts as well as antibacterial activity against Staphylococcus aureus of PCL:HA:ZnO and PCL:ZnO scaffolds were here evaluated. Furthermore, the effect of ZnO nanostructures at different concentrations on in vitro degradation of PCL electrospun scaffolds was analyzed. The results proved that higher concentrations ZnO may induce early mineralization, as indicated by high alkaline phosphatase activity levels, cell proliferation assays and positive Alizarin-RedS stained calcium deposits. Moreover, all PCL:ZnO scaffolds particularly showed antibacterial activity against S. aureus which may be attributed to release of Zn 2+ ions. Additionally, results here obtained showed a variable PCL degradation rate as a function of ZnO concentration. Therefore, this work suggests that our PCL:ZnO scaffolds may be promising and competitive short-, mid-and long-term resorption systems against current clinical solutions for bone tissue regeneration.

Nonvolatile, electric-pulse-induced resistance switching is reported on S and Co doped ZnO thin films deposited on different substrates using magnetron sputtering and laser ablation. Two resistance states were obtained by applying voltage pulses of different polarity. The switching was observed regardless of the substrate, dopant species, or microstructure of the samples. In the Co doped ZnO samples, the two resistance states are remarkably stable and uniform.

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Phonons in bcc Mo, Fe, and Cr have been calculated using embedded-atom-method ͑EAM͒-type and embedded-defect ͑ED͒ potentials. The latter is an extension of the EAM that introduces angular interactions through a many-body approach. In contrast with the EAM formalism, the ED calculated elastic constants can be fitted to the experimental values even in those metals with a negative Cauchy pressure. The contributions of the pair and many-body interaction terms to the phonon frequencies are studied. It is found that the EAM and ED interatomic potentials show some limitations to reproduce the experimental dispersion curves for bcc and fcc structures; such limitations are analyzed. ͓S0163-1829͑97͒04610-9͔

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Magnetic field dependent photoresistivity was measured at 280 K in ZnO ferromagnetic films grown on r-plane Al2O3 under a N2 atmosphere. A correlation between the negative magneto photoresistivity and the existence of defect-induced magnetic order was found. The effect of magnetic field on the transient photoresistivity is to slow down the recombination process enhancing the photocarriers density. The experimental results demonstrate the possibility of tuning photocarriers life time using magnetic field in diluted magnetic semiconductors.