1,720,964 research outputs found
The synergistic role of pH and calcination temperature in sol–gel titanium dioxide powders
No full textTitanium dioxide (TiO2) nanoparticles were prepared by the sol–gel method starting from a volume of 1.5 mL of titanium tetraisopropoxide (TTIP) dissolved in 10 mL of ultrapure water milliQ grade (pH 5). The pH of the solution was adjusted by adding HNO3 and NaOH to reach an acidic and basic character of the sol, respectively. A wide pH range from 1 to 10 was explored. The prepared TiO2 nanopowders were annealed at three different calcination temperatures, 100, 450 and 800 °C for 3 h. The synergic effect of pH and calcination temperature on the structural and morphological properties of TiO2 nanoparticles was investigated by XRD and Raman analyses. At the lowest (100 °C) and highest (800 °C) calcination temperatures, we observed the dominance of anatase and rutile phases, respectively. A mixture of these phases was observed for the titania powders calcinated at 450 °C. In particular, the nanoparticles produced in strong acidic medium showed a coexistence of anatase and rutile with a dominance of rutile, whereas the anatase was the crystalline phase favored in alkaline medium environment
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
TiO2 films by sol-gel spin-coating deposition with microbial antiadhesion properties
No full textIntensive use of antibiotics induced adaptations in bacteria, which developed antibiotic resistance. This is becoming a serious health problem, particularly in the hospital, food industry, or public transport. It is also important to produce surfaces that not only are bactericidal but also prevent adhesion and the consequent biofilm formation, which can make the bacteria resistant to conventional disinfection methods. In this work, a simple and inexpensive method to obtain surfaces TiO2 film coated has been realized to prevent attachment and bacterial proliferation on surfaces. The synthesis and deposition procedure has been finalized to the realization of a uniform coating, whose physical, morphological, and structural features are suitable to inhibit the proliferation of the bacteria and in particular the adhesion of the biofilm. The suitability of the obtained coating has been attested by RBS, X-ray diffraction (XRD), SEM, UV-vis, and Raman techniques. The obtained coatings were homogeneous anatase titania films with an excellent adherence to the substrate and a transmittivity higher than 80% in the visible region. The results show that the TiO2 films considerably reduce microbial contamination on the surface (~98% reduction) feature that makes this coating suitable for antibacterial applications
Nickel doped TiO2 films by a modified laser plasma source for photocatalytic applications
No full textWe reports a study on pure and Ni-doped TiO2 thin films produced via laser ablation technique. The novelty of the work consists that both synthesis and doping were carried out in a single process, using a modified laser ion source to simultaneously make pulsed laser deposition (PLD) and low-energy ion implantation (by post-acceleration method). In particular, two titania films were synthesized via PLD starting from a rutile target. One of the two films was doped with Ni ions, accelerated with a voltage of 20 kV. The total implanted dose, evaluated by a Faraday cup, resulted to be 1 x 10(14) ions/cm(2). The crystalline phase of the obtained TiO2 films was analysed by Raman spectroscopy. A higher photocatalytic activity, measured under UV irradiation using methylene blue, was estimated for the Ni-doped titania film with respect the pure one
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
Nickel doped TiO2 films by a modified laser plasma source for photocatalytic applications
No full textWe reports a study on pure and Ni-doped TiO2 thin films produced via laser ablation technique. The novelty of the work consists that both synthesis and doping were carried out in a single process, using a modified laser ion source to simultaneously make pulsed laser deposition (PLD) and low-energy ion implantation (by post-acceleration method). In particular, two titania films were synthesized via PLD starting from a rutile target. One of the two films was doped with Ni ions, accelerated with a voltage of 20 kV. The total implanted dose, evaluated by a Faraday cup, resulted to be 1 × 1014 ions/cm2. The crystalline phase of the obtained TiO2 films was analysed by Raman spectroscopy. A higher photocatalytic activity, measured under UV irradiation using methylene blue, was estimated for the Ni-doped titania film with respect the pure one
Synthesis and doping of TiO2 thin films via a new type of laser plasma source
No full textThe paper reports the characterization of doped TiO2 films produced by a modified laser plasma source. The peculiarity of the utilized apparatus was that both synthesis and doping were carried out in the same process, via Pulsed Laser deposition (PLD) in vacuum (growth) and by means of low-energy ion implantation or PLD in background gas (doping). Four TiO2 films were produced using a titania sample as target for laser ablation: one pure (used as reference and grown in vacuum), two doped with Cu and Ni ions (the accelerating voltage was 20 kV) and another one doped with nitrogen (using N2 as background gas). The chemical structure of the obtained films was characterized by Raman spectroscopy, whereas their uniformity and thickness by Rutherford Backscattering Spectrometry. We also investigated the photocatalytic activity of the TiO2 films under sunlight and UV irradiations by using methylene blue
Development and application of facilities at the Centre for Applied Physics, Dating and Diagnostics (CEDAD) at the University of Salento during the last 15 years
No full textThe Centre for Dating and Diagnostics was established in 2001 at the University of Salento with the aim of becoming a National Centre for radiocarbon dating by AMS. After more than fifteen years of operation this goal has been fully achieved with thousands of dated samples for researches spanning from Archaeological, Earth and Forensics sciences to industrial and environmental applications. Furthermore, in the frame of different large scale National projects, the experimental potential of the facility has been substantially improved through the installation of new beam lines and experimental set-ups
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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