Cytochrome c peroxidase (CCP) catalyses the reduction of H2O2 to H2O, an important step in the cellular detoxification process. The crystal structure of the di-heme CCP from Pseudomonas nautica 617 was obtained in two different conformations in a redox state with the electron transfer heme reduced. Form IN, obtained at pH 4.0, does not contain Ca2+ and was refined at 2.2 Angstrom resolution. This inactive form presents a closed conformation where the peroxidatic heme adopts a six-ligand coordination, hindering the peroxidatic reaction from taking place. Form OUT is Ca2+ dependent and was crystallized at pH 5.3 and refined at 2.4 Angstrom resolution. This active form shows an open conformation, with release of the distal histidine (His71) ligand, providing peroxide access to the active site. This is the first time that the active and inactive states are reported for a di-heme peroxidase.

The thermal decomposition of 2-azidoacetamide (N3CH2CONH2) has been studied by matrix-isolation infrared spectroscopy and real-time ultraviolet photoelectron spectroscopy. N2, CH2NH, HNCO, CO, NH3, and HCN are observed as high-temperature decomposition products, while at lower temperatures, the novel imine intermediate H2NCOCHNH is observed in the matrix-isolation IR experiments. The identity of this intermediate is confirmed both by ab initio molecular orbital calculations of its IR spectrum and by the temperature dependence and distribution of products in the photoelectron spectroscopy (PES) and IR studies. Mechanisms are proposed for the formation and decomposition of the intermediate consistent both with the observed results and with estimated activation energies based on pathway calculations.

We present a systematic study of atomic binding energies, in the Dirac–Fock approximation, for the Lithium (3 electrons) to the Dubnium (105 electrons) isoelectronic series. In each series we have considered all atomic numbers from the one corresponding to the neutral atom up to Z=118. We have obtained the ground state configurations for several heavy ions with charge larger than one.

The fabrication of high field-effect mobility ZnO thin film transistor (ZnO-TFT) at room temperature by rf magnetron sputtering was discussed. The ZnO used was deposited onto borosilicate glass substrate with a thickness of 1 mm with 100 x 100 mm surface area, coated with a 200 nm sputtered ITO film. The hall mobilities of about 2 cm2 / V s and a carrier concentration of 3 x 1016cm-3 were measured for the films with lower resistivity. It was observed that the ZnO-TFT presented an average optical transmission of 80% in the visibility part of the spectrum.

A study of intrinsic zinc oxide thin film as ozone sensor based on the ultraviolet (UV) photoreduction and subsequent ozone re oxidation of zinc oxide as a fully reversible process was presented. It was found that the film described were produced by spray pyrolysis, dc and rf magnetron sputtering. The dc resistivity of the films changed more than eight orders of magnitude when exposed to an UV dose of 4 mW/cm2. Analysis shows that the porous and textured zinc oxide films produced by spray pyrolysis at low substrate exhibit an excellent ac impedance response.

Ga-doped polycrystalline zinc oxide (GZO) thin films have been deposited at high growth rates by rf magnetron sputtering. The dependence of electrical, optical and morphological properties on the rf power density were investigated. The lowest resistivity of 1.9×10-4 Ωcm was obtained for a rf power density of 9 W/cm2 and an argon sputtering pressure of 0.15 Pa at room temperature. The films are polycrystalline with a hexagonal structure and a strong crystallographic c-axis orientation (002) perpendicular to the substrate surface. The films present an overall transmittance in the visible spectra of about 85%. The low resistivity, accomplished with a high growth rate deposited at room temperature, enables the deposition of these films onto polymeric substrates for flexible optoelectronic devices and displays.

Titanium aluminides are arising as a valuable alternative to superalloys in applications where the ratio resistance/density is important. Together with excellent mechanical and corrosion properties at high temperatures, such characteristics are very attractive for applications in the aeronautical, aerospace and automotive industries. However, the current high selling price, due to high costs of production and raw materials and the need of very specific equipment, are limitative factors for further applications. With the end of the cold war, and the decrease of traditional markets of TiAl, the strategy to develop other applications, strongly depends on the decrease of production costs. An alternative to the present production routes might be the use of traditional casting techniques, by induction melting of the alloy in a ceramic crucible and pouring into ceramic moulds, made by the investment casting process. However, due to the high reactivity of Ti alloys, the use of traditional ceramic materials cannot be used, as they lead to oxide formation and oxygen pick up both from the crucible and the moulding materials. In this work, the relative oxygen concentration of Ti-48Al castings was measured by SIMS ó Secondary Ion Mass Spectrometry. This technique provides a direct measurement of the isotopic composition with high sensitivity. The cylindrical samples were specially prepared to allow the analysis of the area close to the border. Oxygen profiles were acquired for samples obtained with different mould materials. The comparison of such profiles with hardness ones gives insight in the role of the oxygen concentration in the properties of the alloy and in the choice of the most suitable materials for TiAl production

Titanium aluminides are a valuable alternative to superalloys in applications where the ratio resistance/density is important. Since the ordinary production routes lead to high final costs, an alternative might be the use of traditional casting techniques by induction melting of the alloy in a ceramic crucible and pouring into ceramic moulds, made by the investment casting process. However, due to the high reactivity of Ti alloys, the use of traditional ceramic materials cannot be used, as they lead to oxide formation and oxygen pick up from both the crucible and the moulding materials. In this work, the effect of low level contamination was studied by SIMS. Special attention was given to the oxygen concentration for samples obtained with different mould materials. The comparison of SIMS in-depth profiles with hardness profiles, gives insight concerning the significance of the oxygen concentration in the properties of the alloy and regarding the choice of the most suitable materials for TiAl production.

Ion scattering spectroscopy (ISS) is normally considered a non-destructive technique for surface analysis, while secondary ion mass spectrometry (SIMS) is intrinsically destructive. However, both SIMS and ISS use similar primary beams in the kilo-electron-volt region to perform surface analysis. Although energies and projectile mass are chosen in order to minimize or maximize sputtering for each technique, care should be taken when ISS is performed. Indeed, while sputtering is essential for SIMS, it is unwelcome in ISS. In this paper, we discuss how sputtering may become possible by light ions in the energy range of some 100 eV to some keV. We describe the mechanisms and threshold energies, what is preferential sputtering and how large the absolute value of the sputtering yields should be. We also give details about the emission anisotropy of the sputtered particles for single crystals. Finally, we suggest a way to evaluate the erosion rate under typical ISS conditions and we present examples of Heþ and Ar+ on a Ba target.