1,720,974 research outputs found
Cycling behaviour of sponge-like nanostructured ZnO as thin-film Li-ion battery anodes
No full textSingle phase wurtzitic porous ZnO thin films are obtained by a simple two-step method, involving the sputtering deposition of a sponge-like metallic Zn layer, followed by a moderately low temperature treatment for the complete zinc oxidation. Thanks to its 3D nanostructuration, the superimposition of small branches able to grow in length almost isotropically and forming a complex topography, sponge-like ZnO can combine the fast transport properties of one dimensional material and the high surface area usually provided by nanocrystalline electrodes. When galvanostatically tested in lithium cell, after the initial decay, it can provide an almost stable specific capacity higher than 50 μAh cm−2 after prolonged cycling at estimated 0.7 C, with very high Coulombic efficienc
Acquisizione in tempo reale dello spettro emesso dalla plume durante un processo di fotoablazione
No full textAlNx and a-SiOx coatings with corrosion resistance properties for dental implants
No full textAluminium nitride thin films were deposited on titanium fixtures, while silicon oxide thin films were deposited on titanium fixtures and chromium–cobalt substrates, using the RF magnetron sputtering technique. Each coating showed different corrosion behaviours when electrochemical characterisations were
made in a simulated biological environment, i.e. Hank's solution. Although aluminium nitride was more effective in reducing the localised corrosion on titanium implants, silicon oxide showed the best behaviour against general corrosion and results were consistent for the two kinds of substrates. Moreover the application of a SiO2/AlN bilayer onto the Ti fixtures improved the performances of each separate coating. When the coated surfaces were compared to uncoated substrates, there was no statistically significant difference in cell viability in the response of two different human osteoblastic cell lines — Saos-2 and MG-63. Field emission scanning electron microscopy assessed the surface morphology of coated and uncoated samples, whilst Fourier transform infrared spectroscopy was applied to investigate the bonding structure of barrier layers on silicon samples. On the basis of the data obtained, we are of the opinion that the tested
materials show some promising characteristics for the fabrication of novel dental implants with reduced ion release properties
A possible route to minimisation of strain in thick garnet films grown by pulsed laser deposition for optical waveguide applications
No full textPulsed laser deposition (PLD) of Gd3Ga5O12 (GGG) with high crystalline and optical quality has recently been achieved by several research groups. However, the potential of such films (when doped with a laser ion) for device applications such as high-power planar waveguide lasers is still to be realised. Deposition parameters have been optimised in terms of crystalline and optical quality, but, in our experience, the large amount of residual strain in GGG films grown on Y3Al5O12 (YAG) substrates can lead to problems (delamination, cracking etc) during edge-polishing for film thicknesses >40 µm.Films deposited during optimisation runs have been analysed and the effects of deposition parameters on composition and lattice size have been determined. In particular, the results showed that growth at different substrate temperatures can lead to films with the same nominal composition but varying lattice size. Differential thermal expansion between the film and substrate is expected to produce this effect with a trend of increased change in lattice for higher temperatures due to increased residual strain. Lattice values, however, were not found to increase continuously with increasing substrate temperature. This suggests that temperature optimisation may result in reduced thermal expansion mismatch and hence less residual strain. We will discuss optimised deposition parameters for three different PLD systems and report on efforts to obtain strain-free thick films of GGG on YAG
Si-Based Amorphous Thin Films for the Performance Improvement of Dental Prostheses and Implants
No full textIt is well known that determining the physico-chemical surface properties of both dental and intrabony prostheses is a powerful means that may help elucidating some fundamental features of the interface between the recipient tissues and the prosthesis itself. When dealing with dental prostheses (total dentures, fixed dental prostheses, partial removable dental prostheses), a continuous contact with different tissues and body fluids is required for their different parts. Indeed roughness, porosity and surface energy, as well as surface elemental composition, will strongly influence the response of the tissues, eventually contributing to the success or fail of the prosthesis. This is even more true for the implant-supported fixed dental prostheses, where an intra-bony part, i.e. the dental implant, is connected through a transmucous structure, i.e. the implant abutment, to the intraoral part, i.e. the fixed prosthesis. Thus the same titanium material is supposed to enhance both bone and epithelial healing, whilst the intraoral framework and artificial teeth –which may be made by several different materials- are to avoid bacterial adhesion as much as possible. Several surface modification processes are currently used in order to improve the prostheses performances, but many of them are still not completely satisfactory, and a continuous research effort is still required to improve their effectiveness. In this chapter, we describe the use of silicon-based amorphous thin film alloys to improve the performances of dental prostheses and implants. Indeed,
hydrogenated amorphous silicon-based alloys, such as amorphous hydrogenated silicon-oxygen (a-SiOx:H) alloys possess interesting properties, which can be exploited for the surface modification of dental prostheses and implants. They are inert and largely biocompatible materials and do not embed dangerous metallic elements, such as Ni, Al, Cr, or Mo, which could be released into the body during the long term contact within living tissues. Moreover, the hydrogen incorporation, which is typical of amorphous material grown by plasma-assisted CVD techniques, has already been proven helpful in enhancing the biocompatibility of silicon and silicon-based materials. We studied the effects of amorphous silicon-based alloys for the performance improvement of several bulk materials used for the fabrication of prostheses and implants, including ceramics, resins, titanium and cobalt-chromium alloys. The films showed interesting properties as for the bacterial adhesion reduction, the biocompatibility improvement and the corrosion protection of bulk materials under study
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Femtosecond laser-induced forward transfer of thin films using a Triazene polymer sacrificial layer and an active carrier
No full textLaser Induced Forward Transfer (LIFT) is a novel direct write technique for material transfer from thin film precursors. In conventional LIFT the material to be transferred is required to act as its own propellant. This requirement is not compatible with the objective of intact material transfer. Recently, UV-absorbing triazene polymers have been reported to be used as sacrificial layers in LIFT experiments. We report the use of these polymers as sacrificial layers at infrared wavelength (800nm) for transferring gadolinium gallium oxide amorphous thin films. A 150 nm thick film was deposited on a 100 nm thick polymer layer by Pulsed Laser Deposition (PLD), to be used as the donor film. Intact thin films were successfully deposited on a silicon receiver kept at a distance of 400nm. The concept of using the carrier in an active role is a completely new and exciting approach for LIFT
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Current state of the art of pulsed laser deposition: existing capabilities and future trends
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