Thin Films for Medical and Environmental Applications

A material that presents both the appropriate set of bulk properties in conjunction with an optimal surface performance is hardly found. For this reason, there is the need of modifying its surface. This is a standard procedure in many application fields but particularly important in the medical and environmental research. In this chapter, we describe the use of sputtering, as the chosen technology for the deposition of thin films. The use of the modified surfaces in the medical and environmental fields will be highlighted by two case studies in each one. In biomedicine, the surface modification of medical invasive devices for orthopedic and neural applications will be presented. For the environmental aspect, the results of two bioremediation tools, for arsenic and uranium removal, based on the immobilization of bacterial cells will be discussed

Electrochemical characterization of thin passive films on Nb electrodes in H3PO4 solutions

The electrical and semiconducting properties of thin anodic passive films potentiostatically formed (1 V £ Ef £ 5 V vs. sce) on polycrystalline niobium electrodes in aqueous 0.5 mol/L H3PO4 solutions (pH 1.3) were studied, at room temperature, using electrochemical impedance spectroscopy. The data were analysed with a transfer function using a non-linear fitting routine, assuming that the resistance of the film is coupled in series with the faradaic impedance of the Nb(0) Nb(V) reaction, and these in parallel with the capacitance of the passive film/electrolyte interface. The relative permittivity of the films was estimated as about 44. The number concentration of donors (N D) in the films was found to decrease with Ef (i.e., with increasing film thickness). A flat band potential value of -0.72 V was also obtained from Mott-Schottky plots

Chiral forces in longitudinally invariant dielectric photonic waveguides

Optical forces can be chiral when they exhibit opposite signs for the two enantiomeric versions of a chiral molecule or particle. Such forces could be eventually used to separate enantiomers, which could find application in numerous disciplines. Here, we analyze numerically the optical chiral forces arising in the basic element of photonic integrated circuitry: a dielectric waveguide with rectangular cross-section. Such waveguides are inherently lossless thus generating chiral forces that are invariant in the longitudinal direction and therefore enable enantiomeric separation over long (cm-scale) distances. Assuming Brownian motion in a liquid environment, we calculate first the force strength and time span needed to perform the separation of chiral nanoparticles as a function of the radii. Then we analyze the chiral forces produced by the fundamental quasi-TE guided mode in a silicon nitride waveguide and show that it can lead to enantiomeric separation via the transverse spin at short wavelengths (405 nm). At longer wavelengths (1310 nm), the proper combination of degenerate quasi-TE and quasi-TM modes would result in a quasi-circularly polarized mode with intrinsic chirality (helicity), leading to chiral gradient forces that also enable the enantiomeric separation of smaller nanoparticles. We report particle tracking simulations where the optical force field produced by a quasi-TE and a quasi-circular mode proved to separate enantiomers under a time span of two seconds. Our results suggest the viability of enantiomeric separation using simple photonic integrated circuits, though different wavelength windows should be selected according to the nanoparticle size.Comment: 19 pages, 6 figure

University training in energy efficiency to respond to European EPBD objectives. USE Efficiency Project

[EN] Energy efficiency in buildings is one of the main challenges in EU policy, since it is difficult to find common strategies and policies among Member States. This article describes the USE Efficiency project, an initiative to create a common training framework for energy efficiency systems in buildings based on the Energy Performance Building Directive (EPBD), through university actions. Universities and students are proposed as shining examples both for energy efficiency solutions and for energy efficiency behaviour. Moreover, involving university students guarantees acting on closest future market players and most convincing actor in diffusion of public opinions. The project aims to improve energy efficiency in university buildings and to establish training program for students around European countries. In fact, this activity involves 9 Universities (Technology Faculties and Faculties of Engineering) and 4 technological and market players from widespread countries in EU.Initially, a mapping of the methodologies used for evaluating energy efficiency at the different countries is carried out. Students are trained in energy efficiency methods and strategies, having real work experience implementing these Energy Performance Assessment (EPA) methodologies in their own buildings. The wide geographical coverage of the consortium allows an important crossover of methodologies to achieve technical results even to a professional and technological level. Then, the analysed buildings at each university are monitored in order to collect data, which are then used to plan solutions to improve energy performance of the university buildings. This paper describes this innovative training initiative, which involves students as main actors, working and interacting together with professors and technicians in order to improve energy efficiency in their educational centres.This initiative responds to a common effort between 9 European universities and 3 market players, funded by the “Universities and Students for Energy Efficiency (USE Efficiency)” project (Ref. CIP-IEE-2008). The work was completed by the Institute for Energy Engineering located at the Universitat Politècnica de València. The authors deeply thanks the Universitat Politècnica de Valencia and all the organizations involved in this project for their support and, specially, to the European Commission for their funding provision.Peñalvo López, E.; Cárcel Carrasco, FJ.; Montañana Romeu, J.; León Martínez, V. (2019). University training in energy efficiency to respond to European EPBD objectives. USE Efficiency Project. En INNODOCT/18. International Conference on Innovation, Documentation and Education. Editorial Universitat Politècnica de València. 151-165. https://doi.org/10.4995/INN2018.2018.8844OCS15116

Target spinor calibration (TSC) for polarimetric radar cross-section measurements

A new polarimetric calibration method is proposed based on scattering matrix decomposition, via Pauli matrices. This scheme operates with the Pauli target vectors instead of the scattering matrix. The base elements of the Pauli target vectors are the vectors corresponding to the usual calibrators such as sphere, dihedral and 45° rotated dihedral. This fact allows direct and easy calculation of the error coefficients. An experimental validation of this method is presented.Peer Reviewe

Low cost transmission line demonstrator for a novel intermediate level communication engineering laboratory

This paper is devoted to the description of a transmission line laboratory demonstrator for intermediate level communication engineering students, within a course on radiation and guided waves. Student activities have been organized according to the needs of intermediate level students and the objectives of an introductory laboratory, which are substantially different from those of specialized laboratory activities aimed at higher level students and placed just before graduation. Since a large number of students attend these laboratory sessions before they choose their specialty, low cost is an unavoidable requirement to be considered. For this reason, the measurement set-up makes use of standard instrumentation, usually available in a basic electronic laboratory, which allows multiplication of work places at a reasonable cost. Both time domain reflectometry and sinusoidal steady state measurements are presented to characterize the main parameters of a coaxial line. However, discussions are mainly focused on sinusoidal measurements, which are scarce in the literature and exclusively devoted to slotted line measurements. The experimental work undertaken by the students gives them insight into main transmission line parameter and features: line impedance, propagation speed, its behavior as an impedance transformer, the complex nature of the measured magnitudes and the standing wave behavior of voltage and attenuation.Peer Reviewe