Shallow hydroxyapatite coatings pulsed laser deposited onto Al2O3 substrates with controlled porosity: correlation of morphological characteristics with in vitro testing results

We studied the influence of porous Al₂O₃ substrates on Ce-stabilized ZrO₂-doped hydroxyapatite thin films morphology pulsed laser deposited on their top. The porosities of substrates were monitored by changing sintering temperatures and measured with a high pressure Hg porosimeter.The depositions were conducted in 50 Pa water vapors by multipulse ablation of the targets with an UV KrF* (λ = 248 nm, τ ∼ 25 ns) excimer laser. The surface morphology of synthesized nanostructures was investigated by scanning electron microscopy and atomic force microcopy. Ca/P ratio within the range 1.67-1.70 was found for hydroxyapatite coatings by energy dispersive spectroscopy.The films were further seeded with mesenchymal stem cells for in vitro tests. The cells showed good attachment and spreading uniformly covering the entire surface of samples. The complexity of film morphology which is increasing with substrate porosity was shown to have a positive influence on cultivated cells density.     

Characterization of pulsed laser deposited chalcogenide thin layers

In this work we report on pulsed laser deposition (PLD) of chalcogenide thin films from the systems (AsSe)_100−xAgI_x and (AsSe)_100−xAg_x for sensing applications. A KrF* excimer laser (λ = 248 nm; τ_FWHM = 25 ns) was used to ablate the targets that had been prepared from the synthesised chalcogenide materials. The films were deposited in either vacuum (4 × 10⁻⁴ Pa) or argon (5 Pa) on silicon and glass substrates kept at room temperature. The basic properties of the films, including their morphology, topography, structure, and composition were characterised by complementary techniques. Investigations by X-ray diffraction (XRD) confirmed the amorphous nature of the films, as no strong diffraction reflections were found. The film composition was studied by energy dispersive X-ray (EDX) spectroscopy. The morphology of the films investigated by scanning electron microscopy (SEM), revealed a particulate-covered homogeneous surface, typical of PLD. Topographical analyses by atomic force microscopy (AFM) showed that the particulate size was slightly larger in Ar than in vacuum. The uniform surface areas were rather smooth, with root mean square (rms) roughness increasing up to several nanometers with the AgI or Ag doping. Based upon the results from the comprehensive investigation of the basic properties of the chalcogenide films prepared by PLD and their dependence on the process parameters, samples with appropriate sorption properties can be selected for possible applications in cantilever gas sensors.     

Structural investigations of ITO-ZnO films grown by the combinatorial pulsed laser deposition technique

Mixtures of transparent and conductive oxides such as ITO-ZnO have been grown by a combinatorial pulsed laser deposition technique from two targets that were located 15 mm apart. The films were deposited on (1 0 0)Si and quartz substrates that were heated at temperatures from 300 to 500 °C. Measurements of the In to Zn ratios along the transversal axis of the substrates, which passes through the maximum thickness points corresponding to each target position were performed using energy dispersive X-ray spectroscopy and spectroscopic ellipsometry. From simulations of the X-ray reflectivity spectra, collected with a 2 mm mask on different locations along the transversal axis of the samples, the density and thickness of the deposited films were calculated and then the In to Zn ratios. The crystalline structure and electrical properties of the deposited films were also investigated along the same axis. Changes in the ratio of In/Zn along this axis resulted in changes of the film lattice constant and texture.     

Systèmes triples de variétés non holonomes linéaires de l'espace projectif ordinaire

Résumé En employant la méthode du repère mobile, l' A. étudie les systèmes triples de variétés non holonomes en établissant un système complet d'invariants tant finis qu'infinitésimaux dont il donne les significations géométriques. Après avoir considéré des figures et des correspondances locales, l'A. présente des classes de systèmes triples et donne un critère concernant la correspondance d'applicabilité projective entre deux systèmes triples en utilisant les invariants infinitésimaux du typeBompiani. à M. Enrico Bompiani pour son Jubilè scientifique.     

MAPLE applications in studying organic thin films

Thin films of various organic materials have been created by the matrix assisted pulsed laser evaporation (MAPLE) technique. The principles, advantages, and difficulties of deposition are discussed. The focus is on target preparation, solvents, studied materials, and growth rate. Measured solvent transmissions and the results obtained are reported, and an overview of MAPLE applications is presented.     

An interferometric electron density estimate of a TE-CO2 laser sustained plasma in front of a metallic target

A Mach-Zehnder interferometer, using a Q-switched ruby laser as a light source was constructed. It was used for the prime investigation of a TE-CO₂ laser produced plasma in front of a solid target. Plasma refractivity analysis indicates an electron density of 10¹⁸ cm^-3 on the detonation front.     

Entropy Production for a Class of Inverse SRB Measures

We study the entropy production for inverse SRB measures for a class of hyperbolic folded repellers presenting both expanding and contracting directions. We prove that for most such maps we obtain strictly negative entropy production of the respective inverse SRB measures. Moreover we provide concrete examples of hyperbolic folded repellers where this happens.     

Clean,cold, and liquid-free laser transfer of biomaterials

Blister-based laser induced forward transfer (BB-LIFT) is proposed as a promising tool for clean, cold and liquid-free local transfer of various organic substances. The feature of the given technique is that ejection of the material from the target results from non-destructive blistering of a thin metal film covering a transparent support. Applicability of the BB-LIFT driven by nanosecond laser pulses for micro-patterning of few organic Langmuir films was examined. Clean laser transfer with negligible material heating has been demonstrated for the nanoaggregated porphyrin films under optimized processing conditions. However, laser transfer of biopolymers, which form elastic and durable films at the target, meets essential problems and requires new solutions.     

Pulsed laser deposition of semiconducting crystalline double-doped barium titanate thin films on nickel substrates

We synthesized by pulsed laser deposition (Ba,Sr,Y)TiO₃ and (Ba,Pb,Y)TiO₃ thin films on mechanically polished nickel substrates.The synthesized thin films were analyzed for: crystalline structure by X-ray diffractometry, morphology and surface topography by atomic force microscopy, optical and scanning electron microscopy, and elemental composition by energy dispersive X-ray spectroscopy and electrical properties by electrical measurements.We have shown that film properties were determined by the dopants, target composition, and deposition parameters (oxygen pressure, substrate temperature and incident laser fluence). All films exhibited a semiconducting behavior, as proved by the decrease of electrical resistance with heating temperature.