1,720,984 research outputs found
Palladium oxide nanoparticles: Preparation, characterization and catalytic activity evaluation
Full text linkStable palladium oxide nanoparticles were prepared in aqueous suspension with a very simple procedure, by dissolving palladium nitrate in water at a concentration around 10-4 M. UV-visible absorption spectroscopy was adopted to follow the formation of these nanoparticles, which were characterized by TEM microscopy, along with XRD, XPS and Raman measurements. DFT calculations allowed to interpret the Raman data and to clarify the species present at the surface of the nanoparticles. The catalytic activity of the latter was evaluated by monitoring the reduction of p-nitrophenol to p-aminophenol. This investigation paves the way to the use of these colloidal nanoparticles in processes of heterogeneous catalysis, in particular those concerning the catalytic degradation of aromatic derivatives that represent a serious danger for the environment as pollutants, as in the case of p-nitrophenol
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
A new route for caesium lead halide perovskite deposition
No full textInorganic metal halide perovskites are relevant semiconductors for optoelectronic devices. The successful deposition of thin films of CsPbBr3 and CsPbCl3 has recently been obtained by Radio-Frequency magnetron sputtering. In this work we compare the morphological, structural and optical characteristics of the two materials obtained with this deposition technique. A detailed photoluminescence (PL) spectroscopy study of the as-grown samples was conducted at the macro and micro scale in a wide temperature range (10-300 K) to fully characterize the PL on sample areas of square centimeters, to assess the origin of the inhomogeneous broadening and to quantify the PL quantum yield quenching. Our results prove that this technique allows for the realization of high quality nanometric films with controlled thickness of relevance for optoelectronic applications
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
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
Electrochemical stability of steel, Ti, and Cu current collectors in water-in-salt electrolyte for green batteries and supercapacitors
Full text linkThe electrochemical behaviour of steel, copper, and titanium current collectors was studied in aqueous solutions of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) at various concentrations, from 0.5 up to 20 m. As the concentration of the electrolyte increases, the electrochemical window of water stability widens according to the “water-in-salt” concept. The metal grids have been studied electrochemically, both under anodic and cathodic conditions, by means of cyclic voltammetry and chronoamperometry. Subsequently, a microscopic analysis with SEM and compositional analysis with XPS was carried out to evaluate the surface modifications following electrochemical stress. We found that copper is not very suitable for this kind of application, while titanium and steel showed interesting behaviour and large electrochemical window
Characterization of the Response of Magnetron Sputtered In2O3−x Sensors to NO2
Full text linkThe response of resistive In2O3−x sensing devices was investigated as a function of the NO2 concentration in different operative conditions. Sensing layers are 150 nm thick films manufactured by oxygen-free room temperature magnetron sputtering deposition. This technique allows for a facile and fast manufacturing process, at same time providing advantages in terms of gas sensing performances. The oxygen deficiency during growth provides high densities of oxygen vacancies, both on the surface, where they are favoring NO2 absorption reactions, and in the bulk, where they act as donors. This n-type doping allows for conveniently lowering the thin film resistivity, thus avoiding the sophisticated electronic readout required in the case of very high resistance sensing layers. The semiconductor layer was characterized in terms of morphology, composition and electronic properties. The sensor baseline resistance is in the order of kilohms and exhibits remarkable performances with respect to gas sensitivity. The sensor response to NO2 was studied experimentally both in oxygen-rich and oxygen-free atmospheres for different NO2 concentrations and working temperatures. Experimental tests revealed a response of 32%/ppm at 10 ppm NO2 and response times of approximately 2 min at an optimal working temperature of 200 °C. The obtained performance is in line with the requirements of a realistic application scenario, such as in plant condition monitoring
Magnetron Sputtered CsPbCl3 Perovskite Detectors as Real-Time Dosimeters for Clinical Radiotherapy
No full textThe aim of this study is to investigate the feasibility of manufacturing thin real-time relative dosimeters for clinical radiotherapy (RT) with potential applications for transmission monitoring in vivo dosimetry and pre-treatment dose verifications. Thin (≈1 μm) layers of a high sensitivity, wide bandgap semiconductor, the inorganic perovskite CsPbCl3, have been grown for the first time by magnetron sputtering on plastic substrates equipped with electrode arrays. Prototype devices have been tested in real-time configuration to evaluate the dose delivered by a 6 MV photon beam from a linear accelerator. Linearity of the charge with the dose has been verified over three order of magnitudes, linearity of the current signal with the dose rate has been also successfully tested in the range 0.5-4.3 Gy/min. The combination of high sensitivity per unit volume and wide bandgap provides high signal-to-noise ratios, up to 70, even at moderate applied voltages. The Schottky diode configuration allows the detector to operate without bias voltage (null bias).The blocking-barrier structure allows to confine the active volume within sub-millimetric sizes, a quite attractive feature in view to increase granularity and achieve the high spatial resolutions required in modern RT techniques. All the above-mentioned features indeed pave the way to a novel generation of flexible, transmission, real time dosimeters for clinical radiotherapy
Publisher Correction: Fe-functionalized paramagnetic sporopollenin from pollen grains: one-pot synthesis using ionic liquids (Scientific Reports, (2020), 10, 1, (12005), 10.1038/s41598-020-68875-6)
No full textIn the original version of this Article, F. Rossella was incorrectly listed as a corresponding author. The correct corresponding author for this Article is C.S. Pomelli. Correspondence and request for materials should be addressed to [email protected]. This error has now been corrected in the HTML and PDF versions of the Article
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