n/a

n/a

n/a

In this paper we present results of intrinsic/non-doped zinc oxide deposited at room temperature by radio frequency magnetron sputtering able to be used as a semiconductor material on electronic devices, like for example ozone gas sensors, ultra-violet detectors and thin film transistors. These films present a resistivity as high as 2.5×108 Ω cm with an optical transmittance of 90%. Concerning the structural properties, these films are polycrystalline presenting a uniform and very smooth surface. © 2005 Elsevier B.V. All rights reserved.

The gene for pseudoazurin was isolated from Paracoccus pantotrophus LMD 52.44 and expressed in a heterologous system with a yield of 54.3 mg of pure protein per liter of culture. The gene and protein were shown to be identical to those from P. pantotrophus LMD 82.5. The extinction coefficient of the protein was re-evaluated and was found to be 3.00 mM(-1) cm(-1) at 590 nm. It was confirmed that the oxidized protein is in a weak monomer/dimer equilibrium that is ionic-strength-dependent. The pseudoazurin was shown to be a highly active electron donor to cytochrome c peroxidase, and activity showed an ionic strength dependence consistent with an electrostatic interaction. The pseudoazurin has a very large dipole moment, the vector of which is positioned at the putative electron-transfer site, His81, and is conserved in this position across a wide range of blue copper proteins. Binding of the peroxidase to pseudoazurin causes perturbation of a set of NMR resonances associated with residues on the His81 face, including a ring of lysine residues. These lysines are associated with acidic residues just back from the rim, the resonances of which are also affected by binding to the peroxidase. We propose that these acidic residues moderate the electrostatic influence of the lysines and so ensure that specific charge interactions do not form across the interface with the peroxidase.

The phase behaviour of the binary mixture of carbon dioxide and the cobalt complex dicarbonyl(eta(5)-cyclopentadienyl)-cobalt, CPCo(CO)(2), has been investigated. This organometallic compound is one of the most effective catalysts of cyclotrimerization reactions of arylisocyanates and alkynes. Vapour-liquid equilibrium (VLE) measurements were undertaken in a static analytical apparatus at 313.15, 323.15 and 363.15 K at pressures up to 15 MPa. p, T isopleths were measured by a synthetic method in a Cailletet apparatus. Nine different compositions ranging from 17.56 to 94.23 mol% of CO2 were measured up to 15 MPa. Modelling with the Peng-Robinson equation of state (PR EOS) gave reasonable results in the correlation of the experimental phase equilibrium compositions using two temperature-dependent interaction parameters. (C) 2003 Elsevier B.V. All rights reserved.

n/a

The gene for pseudoazurin was isolated from Paracoccus pantotrophus LMD 52.44 and expressed in a heterologous system with a yield of 54.3 mg of pure protein per liter of culture. The gene and protein were shown to be identical to those from P. pantotrophus LMD 82.5. The extinction coefficient of the protein was re-evaluated and was found to be 3.00 mM(-1) cm(-1) at 590 nm. It was confirmed that the oxidized protein is in a weak monomer/dimer equilibrium that is ionic- strength-dependent. The pseudoazurin was shown to be a highly active electron donor to cytochrome c peroxidase, and activity showed an ionic strength dependence consistent with an electrostatic interaction. The pseudoazurin has a very large dipole moment, the vector of which is positioned at the putative electron-transfer site, His81, and is conserved in this position across a wide range of blue copper proteins. Binding of the peroxidase to pseudoazurin causes perturbation of a set of NMR resonances associated with residues on the His81 face, including a ring of lysine residues. These lysines are associated with acidic residues just back from the rim, the resonances of which are also affected by binding to the peroxidase. We propose that these acidic residues moderate the electrostatic influence of the lysines and so ensure that specific charge interactions do not form across the interface with the peroxidase.

The search for new dielectric materials to be used in metal-insulator- semiconductor (MIS) structures to replace the silicon oxide (SiO2) has been growing up. The aim is to have materials with high dielectric constants that could allow the use of thicker films and so, to reduce the role of leakage currents that happens in devices using very thin SiO2 layers or to allow the MIS devices to support high currents, besides having a retain memory effect. In this work, we present data concerning the production of hafnium oxide (HfO2) thin films by radio frequency (rf) sputtering that present suitable characteristics to be used as a gate dielectric, taking advantage of its high dielectric constant and stoichiometry reached under certain deposition conditions. Data concerning the role of the deposition parameters in the films structure and in the electrical properties of the films produced using capacitance-voltage (C-V) and current-voltage (I-V) measurements will be shown, together with data concerning the degree of films' compactness measured by spectroscopic ellipsometry (SE). © 2003 Elsevier B.V. All rights reserved.