Publications

The hematite films were prepared via anodic electrodeposition on FTO and FTO/mesoporous TiO2 substrates. The hematite photoanodes were characterized by X-ray diffraction and scanning electron microscopy. The performance of the prepared hematite photoanodes was assessed based on photocurrent-voltage curves and electrochemical impedance spectra. The modification of the hematite surface with nickel oxide nanoparticles improved the performance of the hematite photoanode while phosphorous doped hematite photoanode shows poor photoactivity. The onset of water oxidation photocurrent was cathodically shifted for hematite photoanodes prepared on FTO/TiO2 substrate.

The aim of our study was to synthesize and evaluate the physicochemical and biological properties of composite films based on poly(lactic-co-glycolic acid) copolymer and quercetin (PLGA/Q) microspheres. During our experiments, we firstly synthesized the PLGA/Q microspheres by using an oil-in-water emulsion-diffusion-evaporation method. Subsequently, the as-prepared composite material was subjected to the matrix assisted pulsed laser evaporation (MAPLE) technique, in order to obtain the PLGA/Q coatings. Relevant compositional and microstructural features of the synthesized samples were obtained by means of Fourier transform infrared spectroscopy (FTIR) and AFM (atomic force microscopy). The long-term biocompatibility of the synthesized films was in vitro evaluated by cellular viability and immunofluorescence assays.

Tungsten trioxide (WO3) is a widely studied material for electrochromic applications. The structure, morphology and optical properties of WO3 thin films, grown by matrix assisted pulsed laser evaporation (MAPLE) from monoclinic WO3 nano-sized particles, were investigated for their possible application as electrochromic layers. A KrF* excimer (lambda = 248 nm, .zeta(FWHM)=25 ns) laser source was used in all experiments. The MAPLE deposited WO3 thin films were studied by atomic force microscopy (AFM), grazing incidence X-ray diffraction (GIXRD) and Fourier transform infrared spectroscopy (FTIR). Cyclic voltammetry measurements were also performed, and the coloring and bleaching were observed. The morpho-structural investigations disclosed the synthesis of single-phase monoclinic WO3 films consisting of crystalline nano-grains embedded in an amorphous matrix. All thin films showed good electrochromic properties, thus validating application of the MAPLE deposition technique for the further development of electrochromic devices.

When a quantum dot is embedded into a superconducting environment, it leads to the formations of localized Shiba states inside the gap. If the Coulomb interaction is sufficiently small, the Shiba states consist of a pair of singlet states and a doublet, that compete for the ground state and induce a quantum phase transition. In the presence of an external microwave field, the Shiba energy spectrum is significantly modified. Moreover, the transmission of the cavity inherits features that can pinpoint the exact location of the quantum critical point. In terms of methods used, our analytical calculations are supplemented by state of the art numerical renormalization group calculations.

The electrospinning technique was employed for the preparation of SnO2 fibers starting from a precursor solution consisting of a tin salt, polyvinylpyrrolidone as carrier polymer and N,N-dimethylformamide as dispersion medium. In order to achieve single-phase crystalline structures, the as-spun fibers were calcined at 500, 700 or 900 degrees C, with two different heating rates of 1 or 10 degrees C/min. The thermally treated samples were characterized in terms of structure, morphology and bandgap by employing X-ray diffraction, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy and UV-Vis spectroscopy. A fine tuning of the bandgap width was attained through the selection of different values for the electrospinning and calcination parameters.

The electrical and photosensing properties correlated with structure and morphology of TiO2/(GeSi/TiO2)(2) multilayers are investigated. The multilayers are prepared by magnetron sputtering followed by rapid thermal annealing. Studies of Raman spectroscopy, transmission electron microscopy and X-ray diffraction are carried out. Measurements of dark current versus voltage and temperature are done. The photosensing properties are studied by measuring photocurrent spectra at different temperatures. We obtain multilayers with 10 - 15 nm Ge0.6Si0.4 nanocrystals (NCs) by annealing at 800 degrees C. We evidence the tunneling mechanism between neighbor NCs (T-1/2 law) in the dark current-temperature dependence. The photocurrent spectrum has a maximum with position shifting from 940 to 980 nm when the measurement temperature increases from 150 to 300 K, being due to the GeSi NCs.

The aim of this study was to investigate the antifungal activity of samarium doped hydroxyapatite (Ca10-xSmx(PO4)(6)(OH)(2), x(Sm) = 0.02 and x(Sm) = 0.05) layers deposited on titanium substrate by a thermal evaporation technique. The morphology of the samarium doped hydroxyapatite layers deposited on a Ti (Ti-Sm:HAp_2 and Ti-Sm: HAp_5) substrate were investigated using scanning electron microscopy (SEM). The antifungal activity of the Sm:HAp layers was assessed using Candida albicans ATCC 10231 fungal strain. The biofilm development of the C. albicans on the Sm: HAp layers was investigated by confocal laser scanning microscopy (CLSM). The results have evidenced a significant inhibition of the fungal cells adherence and biofilm development on the Sm: HAp layers.