Publications

A two-dimensional array of a large number of identical densely-packed indium-oxide nano-columns was prepared by pulsed laser deposition. The structure closely mimics tubular structure of the under-cap layer of tubular mushrooms. The growth was initiated by a dense array of gold or silver nanodots. The resulting structure forms a transparent semiconducting layer whose resistance is highly sensitive to composition of gases in atmosphere. A simple device based on the array of nano-columns is able to accurately monitor gas balance in an open or closed-space environment. The simplicity of the device, its compactness and a well-established process of deposition would allow incorporating it in various equipment of general or personal use. The application of the sensor could range from health monitoring during the exhale to the check of the car exhaust or gas content in homes, offices, workplaces or in the dangerous and threatening environment.

Bioactive materials play an increasingly important role in the biomaterials industry, and are extensively used in a range of applications, including biodegradable metallic implants. We report on Bioactive Glasses (BG) films deposition by pulsed laser techniques onto biodegradable substrates. The BG coatings were obtained using a KrF* excimer laser source (lambda= 248 nm, t(FWHM) <= 25 ns). Their thickness has been determined by Profilometry measurements, whilst their morphology has been analysed by Scanning Electron Microscopy (SEM). The obtained coatings fairly preserved the targets composition and structure, as revealed by Energy Dispersive X-Ray Spectroscopy, Grazing Incidence X-Ray Diffraction, and Fourier Transform Infra-Red Spectroscopy analyses.

One of the simplest routes to prepare polycrystalline Zn(OH)(2) is by coprecipitation, with zinc nitrate as a cation source. However, the addition of even minute amounts of manganese nitrate to the precursors used to prepare pure Zn(OH)(2) results in Mn2+ doped nanostructured ZnO. The comparison with other Mn2+ doped metal hydroxides prepared by the same coprecipitation method, involving metal nitrates precursors, shows that this behavior is unique, pertaining only to Zn(OH)(2). A systematic study of the samples prepared without and with variable amounts of Mn2+ ions, in the 1 to 5000 ppm nominal concentrations range showed that the re-routing of the reaction takes place even for the lowest nominal dopant concentration of 1 ppm. According to X-ray diffraction, transmission electron microscopy and Fourier transform infrared spectroscopy investigations, both crystallite size and morphology of the resulting nanostructured ZnO samples varied with the Mn2+ nominal concentration. Moreover, quantitative electron paramagnetic resonance investigations showed that the incorporation rate of the Mn2+ ions at different sites in the nanostructured ZnO depended on the nominal Mn2+ concentration. The results are discussed in terms of the coordination properties of the Mn2+ and Zn2+ ions and the nature of the reaction precursors.

An alternative and simple coprecipitation method was developed to obtain carbon nanotube-hydroxyapatite (CNTs:HAp) based nanocomposites. The incorporation of CNTs (in a concentration of 5% and 10% of total weight of the nanocomposite) and their impact on both structural and biological properties were studied by using a set of standard complementary biological, microscopic, and spectroscopic techniques. The characteristic peaks of carbon structure in CNTs were not observed in the CNTs-HAp composites by X-ray diffraction analysis. Moreover, FTIR and Raman spectroscopies confirmed the presence of HAp as the main phase of the synthesized CNTs: HAp nanocomposites. The addition of CNTs considerably affected the nanocomposite morphology by increasing the average crystallite size from 18.7 nm (for raw HAp) to 28.6 nm (for CNTs:HAp-10), confirming their proper incorporation. The biocompatibility evaluation of CNTs:HAp-5 and CNTs:HAp-10 nanocomposites included the assessment of several parameters, such as cell viability, antioxidant response, and lipid peroxidation, on human G-292 osteoblast cell line. Our findings revealed good biocompatibility properties for CNTs: HAp nanocomposites prepared by the coprecipitation method supporting their potential uses in orthopedics and prosthetics.

The present work reports a simple adapted co-precipitation method for the synthesis of stable Ce-substituted Ca hydroxyapatite (HAp) nanoparticles. The structural and morphological properties of the Ce-doped hydroxyapatite (Ce:HAp) were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX). The optical properties of the Ce-doped hydroxyapatite were also investigated using Fourier transform infrared (FTIR) spectroscopy, Fourier transform Raman spectroscopy and photoluminescence analysis. The results of the XRD studies revealed the progressive increase in the a-and c-axes with increasing Ce concentration. In the FTIR studies of Ce: HAp powders, a structure similar to that of hydroxyapatite was observed. The IR and Raman wavenumbers and the peak strengths of the bands associated with the P-O and O-H bonds decreased progressively with increasing Ce concentration. All the emission maxima could be attributed to 5d-4f transitions of the Ce ions. The displacements of the maximum emission bands with increasing Cerium in the samples were in agreement with the results obtained by XRD studies. The Ce: HAp samples with x(Ce) = 0.03 and 0.05 exhibited significant antibacterial activity against Staphylococcus aureus and Escherichia coli bacterial strains compared to Ce: HAp samples with xCe = 0 (pure HAp) and 0.01.

The study of various types of nanoparticles with different biomedical applications is of high interest in the last decades. For this purpose, among other techniques, ultrasounds have been used to characterize the aqueous solutions. A non-invasive method is preferable for the characterization of these materials, due to the fact that they are designed to be used for targeted delivery of a chemotherapeutic solution to the tumor site. The present research is focused on ultrasound characterization of solutions based on maghemite and 5-fluorouracil.

Aluminum Nitride (AlN) films were deposited at 450 degrees C in nitrogen ambient at a pressure of 0.1 Pa and at a laser incident fluence of similar to 3 J/cm(2) and pulse repetition rate of 40 Hz. Grazing Incidence X-ray Diffraction patterns evidenced the presence of nanocrystallites in the amorphous AlN matrix. In the FTIR spectra the characteristic Reststrahlen band of AlN crystal with a hexagonal lattice is observed but it is quite broadened (950-550 cm(-1)). The angular dependence of the reflectance spectra in p-polarised incidence radiation demonstrates the sensitivity of the A(1)LO phonon mode of the AlN nanocrystallites to their orientation toward the normal to the substrate surface. With decrease of the incidence beam angle the intensity of the A(1)LO phonon mode diminishes and softening of the resonance frequency occurs.

The aim of this study was to evaluate the adhesion of different bioceramic coatings deposited by radio frequency magnetron sputtering on the biodegradable implant-type magnesium-calcium (MgCa) alloys. Hydroxyapatite (HA) and bioactive glass (BG) were chosen as coating materials, due to their remarkable biological potential. The morphology, composition, structure and adhesion of the deposited thin coatings was characterized by scanning electron microscopy, atomic force microscopy, energy dispersive X-ray spectroscopy, grazing incidence X-ray diffraction, Fourier transform infrared spectroscopy and pull-out adherence measurements. A variation of the coating-to-substrate adhesion has been recorded and correlated with the physico-chemical results. The bonding strength values of the coatings were promising (being superior to the ISO13779-2:2008 fabrication standard for load-bearing biomedical coatings), and thus, encourage us to further proceed with the biological evaluation of the HA or BG coatings-MgCa substrate couples.

The influence of the heat treatments on the martensitic transformation, magnetic properties and thermo- and magnetic induced strain on Ni50Fe20Ga27Cu3 ferromagnetic shape memory alloy prepared as ribbons by melt spinning technique are investigated. The degree of atomic order as effect of different thermal treatments produces important changes in the magneto-crystalline anisotropy of the martensite phase. The anomalies evidenced in the thermo-and magnetic-strain curves are discussed and correlated with the thermo-magnetic data. The transformation-induced strains with and without magnetic field have been measured, the results setting out the influence of the pre-martensitic transformation. Copyright (C) 2016 The Authors. Published by Elsevier B.V.

In this paper, the design of aperture-couplet rectangular dielectric resonator antennas arrays is illustrated. The effect of slot feed on the dielectric resonator antenna (DRA) and the effect of the spacing between array elements is observed. This paperwork can be useful for WLAN applications with the operating frequency 5.8 GHz.