1,720,965 research outputs found
Novel lead battery recycling process combining pyrometallurgical anode preparation and electrorefining
No full textLead acid batteries are processed mainly by using pyrometallurgical operations with problems related to SO2 evolution. Many efforts have been devoted to solving this concern. In this work, where only the anode preparation was a pyrometallurgical process, this problem has been overcome by limiting the process temperature. Several tests have been carried out in order to determine the starting mix composition that allows to reduce the process temperature and then SO2 emissions. Three different anode types were cast and tested. Independently on the anode type, the complex composition of the anode requires to design a special electrolytic cell composed by two different compartments. Preliminary electrorefining tests highlighted that the best results were obtainable by using the anode cast in a titanium holder that allowed to obtain high-purity lead, high anode durability, and low quantity of anodic mud. By using this anode, the specific energy consumption varied over the 0.04–0.17 kWh/kg range. Graphic Abstract: [Figure not available: see fulltext.
Neodymium recovery from scrap magnet using ammonium persulfate
Full text linkThis study proposes a novel leaching methodology to recover neodymium from scrap magnet using ammonium persulfate ((NH4)2S2O8) solutions. The NdFeB magnets from obsolete Hard-Disk-Drives were physically treated by thermal demagnetization (400 °C, 45 min) and mechanical crushing (< 420 μm). The chemical composition of the ground sample was Nd: 31.5 wt%, Fe: 64.8 wt%, Co: 1.9 wt%, Ni: 0.6 wt%. Diagrams of equilibrium phases (Eh vs. pH) were designed to determine the predominance of the formed species in the (NH4)2S2O8 system. Ammonium persulfate aqueous solutions were prepared to generate oxidative sulfate radicals. These radicals allowed to leach the ground samples of NdFeB magnets and recover of neodymium sulfate. The influence of (NH4)2S2O8 concentration (0.7–1.3 M), temperature (25–75 °C) and L/S ratio (25–50 mL/g) on NdFeB magnets leaching was investigated employing analysis of variance in a 23 full factorial experimental design. At the optimal conditions, quantities >98% of NdFeB magnets were leached after 15 min reaction time. Neodymium sulfate was selectively recovered as crystals, and evaluated by chemical and crystallographic analyses. The findings presented in this investigation suggest that neodymium could be recovered from scrap magnet using an eco-friendly leaching methodology assisted by ammonium persulfate
Elaboración de un cemento óseo de fosfato de calcio con una adición de biovidrio
Full text linkResumenUn cemento óseo se sintetizó a partir CaCO3 y CaHPO4, en un tratamiento térmico a 1.400°C, el material sintetizado fue enfriado rápidamente, con un chorro de aire. El cemento óseo fue mezclado con biovidrio en un 10% en peso (BC-10BG) y luego molido y caracterizado mediante Distribución de Tamaño de Partícula (DTP), Difracción y Fluorescencia de rayos X (DRX y FRX). La mezcla, cemento-biovidrio, y el cemento sólo fueron caracterizados fisicomecánicamente con pruebas de resistencia a la compresión, microdureza, tiempo de cohesión y fraguado. Con el fin de observar tendencias a la precipitación en los estudios in-vitro, se evaluaron adicionalmente otras dos composiciones con biovidrio del 5 y del 15% en peso, por DRX, SEM y FTIR-ATR. Las fases cristalinas encontradas inicialmente corresponden en el cemento óseo al α-TCP, β-TCP, Ca2P2O7 y CaHPO4, por su parte en el biovidrio se detectó, en una parte de su estructura cristalina, la fase whitlockita. En términos físicos, los tiempos de manipulación y las propiedades mecánicas corresponden a un cemento para el relleno de cavidades óseas. Las pruebas in-vitro mostraron un efecto bioactivo progresivo conforme aumenta el tiempo de exposición.AbstractBone cement is synthesized using CaCO3 and CaHPO4, in a thermal treatment at 1400°C. The mixture was rapidly cooled with a stream of forced air; bone cement was mixed with 10%wt. Bioglass (BC-10BG) later milled and characterized milled and characterized by Particle Size Distribution (PSD), X-ray diffraction and fluorescence (XRD and XRF). The mixing (Bone cement-Bioglass) and bone cement alone were characterized physicmechamically through testing compressive strength, microhardness, cohesive and setting times; in order to see precipitation trends were carried out in-vitro tests. Additionally, two compositions more of bioglass (5 and 15% wt.) were evaluated by XRD, SEM and FTIR-ATR. The crystalline phases of α-TCP y β-TCP, Ca2P2O7 y CaHPO4 were related to bone cement and whitlockita phase was in agreement with bioglass in one part of its crystalline structure. Physically handling times and the mechanical properties correspond to bone cement for filling cavities. The in-vitro tests showed a progressive bioactive effect with increase the exposition time
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
Static and dynamic weighing of rolling stocks by mean of a customized FBG-Sensorized-Patch
Full text linkThe structural health monitoring (SHM) of an infrastructure is of fundamental importance for the structure and people safety. Fiber Bragg Grating (FBG) sensors allow to design for each application, a tailored array of quasi-distributed sensors integrated to the infrastructure. To ensure the structural integrity of the railways is crucial to verify that the infrastructures comply with safety requirements to carry out their task. Railways rolling stock must comply with speed limits, the maximum number of wagons, maximum weight limit distributed on each axis of the wagons and the allowed number of trains on specific routes. The identification of the vertical load acting on each wheel is fundamental for the safety of a rolling-stock moving on a railway line. This paper presents the results of a test campaign on sensitive smart patches for static and dynamic weighing of trains. The system aims to generate a gripping system based on the magnetic force of a plastoferrite patch, taking advantage of the peculiarity that the rails are made of ferritic steel. This solution has the benefit of simplifying and speeding up the installation process and enabling a fast and easy removal or change in the configuration of the sensors array on the rail
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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