1,721,064 research outputs found
Dispositivo a cristalli liquidi per la realizzazione di maschere ad oscuramento pilotato nella saldatura elettrica
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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 proposal of microtomography evaluation for restoration interface gaps
No full textNowadays, several adhesive systems are used in dental restoration and they're evaluated by clinical research. In vitro evaluations are often made by means of traditional observation techniques (for example scanning electron microscope (SEM), while 3D cone-beam microtomography technique (3D micro-CT), that can be able to generate 3D sample images without any sample treatment during acquisition data, is going to be used a lot in the next few years. In dental cavity restored with composite, it is possible to predict the presence of gaps due to polymerization shrinkage; that is the reason this work purpose is to reveal by 3D images and measure by micro-CT analysis the voids generated applying the most used adhesive systems at the moment. By means of microtomographic analysis is proposed an aid to overcome bidimensional SEM investigation limits like random observation of sample surface, sample sectioning (to see inside it with the relative possible structural alterations induced on the same sample) and the gold sputtering treatment. For this experimental work, human crown teeth have been selected, all restored with the same composite material, using five adhesive systems. After about 48 hours each tooth has been acquired by means of Skyscan 1072 micro-CT instrument and then processed by 3D reconstruction and micro-CT analyser software. Three adhesive systems have showed 3D micro-CT images with not as much voids as expected, with a very little extent. This kind of micro-CT in vitro evaluation proposal suggests a method to observe and quantify the voids generated after polymerization shrinkage during tooth restoration
Gas-in-Liquid Foam Templating as a Method for the Production of Highly Porous Scaffolds
No full textIn the present work, a novel synthetic methodology for the preparation of scaffold of biopolymeric nature is described. In particular, a porous gelatin scaffold was prepared by foam templating. The gas phase, nitrogen, was
generated by means of the reaction between sulfamic acid and sodium nitrite in situ a concentrated solution of gelatin and in the presence of a suitable polymeric surfactant in association with sodium dodecyl sulfate. The
foam was prepared at a temperature of 45 °C and then let gel at 5 °C. After purification, the physical gel was auto-cross-linked with EDC and freeze-dried. The scaffold synthesized with this technique presents a morphology
characterized by voids of spherical symmetry highly interconnected by a plurality of interconnects, and, as a consequence, is particularly suited for cell culturing. In more quantitative terms, voids and interconnects are
characterized by an average diameter of 230 and 90 μm, respectively. Preliminary tests of cell culturing demonstrated the suitability of such a scaffold for tissue engineering applications
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