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This paper presents some studies about the preparation by matrix-assisted pulsed laser evaporation (MAPLE) technique of organic bulk heterojunctions made from the mixture of a star-shaped arylenevinylene compound, 4,4′,4″-tris[(4′-diphenylamino)styryl] triphenylamine as donor and fullerene derivative, [6, 6]-phenyl C61 butyric acid butyl ester, as acceptor, in the weight ratio 1:2. The mixed layer has been characterized by spectroscopic (UV-Vis, Fourier transform infrared) and microscopic (AFM) methods, and the effects of the deposition conditions (number of pulses) and of a buffer layer of poly(aniline-co-aniline propane sulfonic acid) or poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) have been analyzed. The study of the electrical properties has revealed a typical solar cell behavior for the heterostructure glass/ITO/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)/4,4′,4″-tris[(4′-diphenylamino)styryl] triphenylamine: [6, 6]-phenyl C61 butyric acid butyl ester/Al, confirming that MAPLE could be an adequate method for the preparation of active layer based on bulk heterojunction for solar cells. [ABSTRACT FROM AUTHOR]

Cobalt-doped vanadium oxide thin layers prepared by pulsed laser ablation are investigated from the following points of view: (1) the chemical states by X-ray photoelectron spectroscopy (XPS), (2) the local atomic order by X-ray absorption fine structure at both vanadium and cobalt K-edges, (3) the morphology of the films by atomic force microscopy (AFM) and (4) the magnetic properties by magneto-optical Kerr effect (MOKE). The chemical composition of the host matrix was found to be close to VO2 at the sample surface, with V2O3 in the bulk. Co ions are found near the surface in high ionisation states Co4+ (for the samples synthesised in a high vacuum condition, denoted by VO1), or with Co(4-δ)+ (for the samples synthesised in an oxygen atmosphere, denoted by VO2), whereas in the bulk, Co1.5+ is obtained for VO1 and Co2+ is obtained for VO2. The AFM revealed nanoparticles with sizes 10-25 nm for VO1 samples, whereas a few bigger nanoparticles are observed for VO2 samples. The VO1 samples presented high coercitive fields with a relatively low saturation magnetisation at room temperature, superposed with a superparamagnetic component attributed to the observed nanoparticles, whereas the VO2 samples presented double-loop hysteresis curves, indicating the co-existence of two kinds of magnetic moieties with antiparallel coupling at zero applied field. The proposed two magnetic phases are Co-doped V2O3 and VO2. [ABSTRACT FROM AUTHOR]

Abstract: ZrC films were grown on (100) Si substrates by the pulsed laser deposition (PLD) technique using a KrF excimer laser working at 40Hz. The nominal substrate temperature during depositions was set at 300°C and the cooling rate was 5°C/min. X-ray diffraction investigations showed that films deposited under residual vacuum or under 2×10−3 Pa of CH4 atmosphere were crystalline, exhibiting a (200)-axis texture, while those deposited under 2×10−2 Pa of CH4 atmosphere were found to be equiaxed and with smaller grain size. The surface elemental composition of as-deposited films, analyzed by Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS), showed the usual high oxygen contamination of carbides. Once the topmost 2–4nm region was removed, the oxygen concentration rapidly decreased, down to around 3–8% only in bulk. Simulations of the X-ray reflectivity (XRR) curves indicated a smooth surface morphology, with roughness values below 1nm (rms) and films density values of around 6.30–6.45g/cm3, very close to the bulk density. The growth rate, estimated from thickness measurements by XRR was around 8.25nm/min. Nanoindentation results showed for the best quality ZrC films a hardness of 27.6GPa and a reduced modulus of 228GPa. [Copyright &y& Elsevier]

Abstract: The increasing interest in strontium incorporation into biomaterials for hard tissue repair is justified by the growing evidence of its beneficial effect on bone. We successfully synthesized hydroxyapatite (HA) thin films with different extents of strontium substitution for calcium (0, 1, 3 or 7at.%) by pulsed-laser deposition. The coatings displayed a granular surface and a good degree of crystallinity, which slightly diminished as strontium content increased. Osteoblast-like MG63 cells and human osteoclasts were cultured on the thin films up to 21 days. MG63 cells grown on the strontium-doped HA coatings displayed normal morphology, good proliferation and increased values of the differentiation parameters, whereas the number of osteoclasts was negatively influenced by the presence of strontium. The positive effect of the ion on bone cells was particularly evident in the case of coatings deposited from HA at relatively high strontium contents (3–7%), where significantly increased values of alkaline phosphatase activity, osteocalcin, type I collagen and osteoprotegerin/TNF-related activation-induced cytokine receptor ratio, and considerably reduced values of osteoclast proliferation, were observed. [Copyright &y& Elsevier]

Abstract: Pulse shaping introduces the method that makes possible the production of tunable arbitrary shaped pulses. We extend this method to control the prevalent growth of cubic SiC films on Si (100) substrates by pulsed laser deposition at temperatures around 973K from a SiC target in vacuum. We used a laser system generating 200fs pulses duration at 800nm with 600μJ at 1kHz. The obtained structures are investigated by electron microscopy, X-ray diffraction and profilometry. We observed grains embedded in an amorphous texture, characteristic in our opinion to the depositions obtained with very short pulses. We present a comparison of deposited films with and without pulse shaping. Pulse shaping promotes increased crystallization and results in the deposition of thin structures of cubic SiC with a strongly reduced density of particulates, under similar deposition conditions. [Copyright &y& Elsevier]

We extended for the first time pulsed laser ablation to the deposition of octacalcium phosphate Ca8H2(PO4)6·5H2O (OCP) thin films. The depositions were performed with a pulsed UV laser source (λ=248 nm, τ⩾20 ns) in a flux of hot water vapors. The targets were sintered from crystalline OCP powder and the laser ablation fluence was set at values of 1.5–2 J/cm2. During depositions the collectors, Si or Ti substrates, were maintained at a constant temperature within the range 20–200°C. The resulting structures were submitted to heat treatment in hot water vapors for up to 6 h. The best results were obtained at a substrate temperature of 150°C during both deposition and post-deposition treatment. High-resolution electron microscopy and XRD at grazing incidence indicated that the coatings obtained were made of nanocrystalline OCP. Cross-section TEM investigations showed that the coatings contained droplets stacked on Ti substrates as well as distributed across the entire thickness of the arborescence-like structure layers. The results of WST-1 assay, cell adherence, DNA replication, and caspase-1 activity confirmed the good biocompatibility of the coatings. [Copyright &y& Elsevier]

Abstract: We achieved the growth of cubic silicon carbide (SiC) films on (100)Si substrates by pulsed laser deposition (PLD) at moderate temperatures such as 750°C, from a SiC target in vacuum. The as-deposited films are morphologically and structurally characterized by scanning electron microscopy (SEM), conventional and high-resolution transmission electron microscopy (TEM/HRTEM). The morphology of deposited films is dominated by columns nucleated from a thin nanostructured beta silicon carbide (β-SiC) interface layer. The combined effects of columnar growth, tilted facets of the emerging columns and the presence of particulates on the film surface, lead to a rather rough surface of the films. [Copyright &y& Elsevier]

Abstract: We have performed spectroscopic analysis of the plasma produced by pulsed laser ablation of brass in a low pressure argon atmosphere. The intensities of several spectral lines of copper, zinc and lead were measured for succeeding laser pulses applied to the same irradiation site. The intensities and spectral shapes of the observed transitions were compared to the spectral radiance computed for plasma in local thermal equilibrium. At a delay of 600ns after the laser pulse, the plasma is characterized by typical values of temperature and electron density of 1.1×104 K and 1.2×1017 cm−3, respectively, and an elemental composition equal to that of the sample. Small changes of spectral line intensities were observed with increasing number of applied laser pulses. They were attributed to the alteration of the plume expansion dynamics as a consequence of crater formation on the sample surface. The results indicate that the mass transfer from the solid to the plasma is stoichiometric. [Copyright &y& Elsevier]

Abstract: Octacalcium phosphate (OCP) and Mn2+-doped carbonate hydroxyapatite (Mn-CHA) thin films were deposited on pure, highly polished and chemically etched Ti substrates with pulsed laser deposition. The coatings exhibit different composition, crystallinity and morphology that might affect their osteoconductivity. Human osteoblasts were cultured on the surfaces of OCP and Mn-CHA thin films, and the cell attachment, proliferation and differentiation were evaluated up to 21 days. The cells showed a normal morphology and a very good rate of proliferation and viability in every experimental time. Alkaline phosphatase activity was always higher than the control and Ti groups. From days 7 to 21 collagen type I production was higher in comparison with control and Ti groups. The level of transforming growth factor beta 1 (TGF-β1) was lower at 3 and 7 days, but reached the highest values during following experimental times (14 and 21 days). Our data demonstrate that both calcium phosphate coatings favour osteoblasts proliferation, activation of their metabolism and differentiation. [Copyright &y& Elsevier]