Amongst applications of high temperature superconductors, fault current limiters are foreseen as one of the most promising in power systems. Several topologies have been developed in the last years, taking advantage of different superconductors? properties. Increasing distributed generation (DG) penetration, based on renewable energy, adds new short-circuit sources to electrical grids, which brings several energy quality and protection issues. Superconducting fault current limiters can obviate these problems, representing thus an enabling technology for DG penetration. In this paper current limiter topologies are presented, its operations principles, strengths and weaknesses, in the context of these DG grids. In the end, future trends are discussed.

The invention consists in a polyphase motor and operating system thereof that allows obtaining an arbitrary relation of the number of magnetic poles without mechanical commutations within the stator. The number of slots of the latter is ideally given by the least common multiple between the required pole relations. The stator is polyphasic, and the rotor is that of an induction or hysteresis motor. The motor is designed for applications where a large range of operation requiring maximum yield and?or smooth speed?torque (or force, depending on whether the motor is rotary or linear) transitions. This is the case of electric vehicle traction. The operating system receives control references via a controller that compares them with the signals read by the sensor(s). The control action feeds a polyphase inverter for generating the voltages or currents that feed the stator. The speed, torque, or position values are measured in the rotor.

High temperature superconducting (HTS) machines are recognized to offer several advantageous features when comparing to conventional ones. Amongst these, highlights the decrease in weight and volume of the machines, due to increased current density in conductors or the absence of iron slots' teeth; or the decrease in AC losses and consequent higher efficiency of the machines, even accounting for cryogenics. These concepts have been already demonstrated and some machines have even achieved commercial stage. In this paper, several alternative approaches are applied to electrical motors employing HTS materials. The first one is an all superconducting linear motor, where copper conductors and permanent magnets are replaced by Bi-2223 windings and trapped flux magnets, taking advantage of stable levitation due to flux pinning, higher current densities and higher excitation field. The second is an induction disk motor with Bi-2223 armature, where iron, ironless and hybrid approaches are compared. Finally, an innovative command strategy, consisting of an electronically variable pole pairs' number approach, is applied to a superconducting hysteresis disk motor. All these concepts are being investigated and simulation and experimental results are presented.

A fluorene-based pi-conjugated copolymer with on-chain dibenzoborole units was used in the development of a nanocoated gold interdigitated microelectrode array device which successfully detects fluoride in a broad range of concentrations (10(-11)-10(-4) M) in aqueous solution, upon impedance spectroscopy measurements. A calibration curve obtained over this range of concentrations and a new analytical method based on impedance spectroscopy measurements in aqueous solution is proposed. The sensor nanofilm was produced by spin-coating and diagnosed via spectroscopic ellipsometry, AFM, and electrically conductivity techniques. Changes in the conductivity due to the boron-fluoride complex formation seem to be the major mechanism behind the dependence of impedimetric results on the fluoride concentration. (C) 2010 Elsevier B.V. All rights reserved.

A fluorene-based pi-conjugated copolymer with on-chain dibenzoborole units was used in the development of a nanocoated gold interdigitated microelectrode array device which successfully detects fluoride in a broad range of concentrations (10(-11)-10(-4) M) in aqueous solution, upon impedance spectroscopy measurements. A calibration curve obtained over this range of concentrations and a new analytical method based on impedance spectroscopy measurements in aqueous solution is proposed. The sensor nanofilm was produced by spin-coating and diagnosed via spectroscopic ellipsometry, AFM, and electrically conductivity techniques. Changes in the conductivity due to the boron-fluoride complex formation seem to be the major mechanism behind the dependence of impedimetric results on the fluoride concentration. (C) 2010 Elsevier B.V. All rights reserved.

Pressure perturbation calorimetry measurements on a range of cyclodextrin adamantane, protein ligand (lysozyme-(GlcNac)(3) and ribonuclease-2'CMP) and protein-protein (cytochrome c peroxidase-pseudoazurin) complexes in aqueous solution show consistent reductions in thermal expansibilities compared to the uncomplexed molecules. Thermodynamic data for binding, obtained by titration calorimetry, are also reported. Changes in molar expansibilities can be related to the decrease in solvation during complexation. Although reasonable estimates for numbers of displaced water molecules may be obtained in the case of rigid cyclodextrin-adamantane complexes, protein expansibility data are less easily reconciled. Comparison of data from this wide range of systems indicates that effects are not simply related to changes in solvent-accessible surface area, but may also involve changes in macromolecular dynamics and flexibility. This adds to the growing consensus that understanding thermodynamic parameters associated with noncovalent interactions requires consideration of changes in internal macromolecular fluctuations and dynamics that may not be related to surface area-related solvation effects alone.

The retrofit of reinforced concrete columns with FRP jackets has received considerable attention in recent years. The advantages of this technique compared to other similar techniques include the high strength-weight and stiffness-weight ratios of FRP (Fibre Reinforced Plastics), the strength and ductility increase of RC columns confined with FRP jackets as well as the fact that FRP external shells prevent or mitigate environmental degradation of the concrete and consequent corrosion of the steel reinforcement. Furthermore, this method also reduces the column transversal deformation and prevents the buckling of longitudinal reinforcement. Twenty five experimental tests were carried out on reinforced concrete columns confined with CFRP composites, and subjected to axial monotonic compression. In order to evaluate the influence of several parameters on the mechanical behavior of the columns, the height of the columns was maintained, while changing other parameters: the diameter of the columns, the type of material (plain or reinforced concrete), the steel hoop spacing of the RC columns and the number of CFRP layers. Predictive equations, based on the experimental analysis, are proposed to estimate the compressive strength of the confined concrete, the maximum axial load and the axial or the lateral failure strain of circular RC columns jacketed with CFRP. A stress-strain model for CFRP confined concrete in compression, which considers the effect of the CFRP and the transversal reinforcement on the confined compressive strength of the column is also proposed. The curves, axial load versus axial or lateral strain of the RC column, are simulated based on the stress-strain model and include the longitudinal reinforcement effect. The results demonstrate that the model and the predictive equations represent very well the axial compression behavior of RC circular columns confined with CFRP. The applicability of this model to a large spectrum of RC column dimensions is its main advantage.

The final step of bacterial denitrification, the two-electron reduction of N2O to N-2, is catalyzed by a multi-copper enzyme named nitrous oxide reductase. The catalytic centre of this enzyme is a tetranuclear copper site called CuZ, unique in biological systems. The in vitro reconstruction of the activity requires a slow activation in the presence of the artificial electron donor, reduced methyl viologen, necessary to reduce CuZ from the resting non-active state (1Cu(II)/3Cu(I)) to the fully reduced state (4Cu(I)), in contrast to the turnover cycle, which is very fast. In the present work, the direct reaction of the activated form of Pseudomonas nautica nitrous oxide reductase with stoichiometric amounts of N2O allowed the identification of a new reactive intermediate of the catalytic centre, CuZA degrees, in the turnover cycle, characterized by an intense absorption band at 680 nm. Moreover, the first mediated electrochemical study of Ps. nautica nitrous oxide reductase with its physiological electron donor, cytochrome c-552, was performed. The intermolecular electron transfer was analysed by cyclic voltammetry, under catalytic conditions, and a second-order rate constant of (5.5 +/- A 0.9) x 10(5) M-1 s(-1) was determined. Both the reaction of stoichiometric amounts of substrate and the electrochemical studies show that the active CuZA degrees species, generated in the absence of reductants, can rearrange to the resting non-active CuZ state. In this light, new aspects of the catalytic and activation/inactivation mechanism of the enzyme are discussed.

This paper analyses and compares the dynamic behavior of superelastic shape memory alloy (SMA) systems based on two different constitutive models. The first model, although being able to describe the response of the material to complex uniaxial loading histories, is temperature and rate independent. Thesecond model couples the mechanical and kinetic laws of the material with a balance equation considering the thermal effects. After numerical validation and calibration, the behavior of these two models is tested in single degree of freedom dynamic systems, with SMAs acting as restoring elements. Different dynamic loads are considered, including artificially generated seismic actions, in a numerical model of a railway viaduct. Finally, it is shown that, in spite of its simplicity, the temperature- and rate-independent modelproduces a set of very satisfying results. This, together with its robustness and straightforward computational implementation, yields a very appealing numerical tool to simulate superelastic passive control applications.

In view of the increasing need for larger-area display devices with improved image quality it becomes increasingly important to decrease resistivity while maintaining transparency in transparent conducting oxides (TCOs). Accomplishing the goal of increased conductivity and transparency will require a deeper understanding of the relationships between the structure and the electro-optical properties of these materials. In this work we study the role of tin doping in InOx thin films. Undoped indium oxide (InOx) and indium tin oxide (ITO) thin films were deposited at room temperature by radio-frequency plasma enhanced reactive thermal evaporation (rf-PERTE), a new technique recently developed in our laboratory using as evaporation source either In rods or a 90%In:10%Sn alloy, respectively. The two most important macroscopic properties-optical transparency and electrical resistivity-seem to be independent of the tin content in these deposition conditions. Results show that the films present a visible transmittance of the order of 82%, and an electrical resistivity of about 8 x 10(-4) Omega . cm. Surface morphology characterization made by atomic force microscopy (AFM) showed that homogeneity of the films deposited from a 90%In:10%Sn alloy is enhanced (a film with small and compact grains is produced) and consequently a smooth surface with reduced roughness and with similar grain size and shape is obtained. Films deposited from pure In rods evaporation source show the presence of aggregates randomly distributed above a film tissue formed of thinner grains.