Publications by authors named "G N Constantinides"

This study considers the influence of purity and surface area on the thermal and oxidation properties of hexagonal boron nitride (h-BN) nanoplatelets, which represent crucial factors in high-temperature oxidizing environments. Three h-BN nanoplatelet-based materials, synthesized with different purity levels and surface areas (~3, ~56, and ~140 m/g), were compared, including a commercial BN reference. All materials were systematically analyzed by various characterization techniques, including gas pycnometry, scanning electron microscopy, X-ray diffraction, Fourier-transform infrared radiation, X-ray photoelectron spectroscopy, gas sorption analysis, and thermal gravimetric analysis coupled with differential scanning calorimetry.

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The adsorption of actinide ions (Am(III) and U(VI)) from aqueous solutions using pristine and oxidized carbon fabrics was investigated by means of batch experiments at different pH values (pH 4, 7 and 9) and temperatures (25, 35 and 45 °C) under ambient atmospheric conditions. The experimental results indicated that both the pH and the fabric texture affected the adsorption rate and the relative removal efficiency, which was 70% and 100% for Am(III) and U(VI), respectively. The K (L/kg) values for U(VI) were generally found to be higher (2 < log(K)< 3) than the corresponding values for Am(III) adsorption (1.

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Objective: The present study determined the mechanical properties and the wear behavior, as results of the micro(nano)structure, of the enamel, transition, and dentine layers, which comprise the polychromic multilayer zirconia materials of hybrid composition fabricated by milling technology.

Materials And Methods: Prismatic blocks were fabricated from two commercial pre-sintered dental polychromic multilayer zirconia materials of hybrid composition, IPS e.max ZirCAD Prime (medium and high translucency, from the dentine to the incisal layer) and 3D Pro ML (translucency gradient, from the dentine to the incisal layer) by milling technique, and then, cut into 3 distinct parts to separate the enamel, transition, and dentine layers.

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Article Synopsis
  • Microbial electrosynthesis (MES) is being researched for its ability to convert CO into useful products, but the use of costly ion exchange membranes limits its commercial application.
  • This study focused on converting CO to methane (CH) using membraneless MES with anaerobic granular sludge, testing both plain carbon cloth and carbon cloth functionalized with copper nanoparticles (Cu NPs).
  • Results showed that while methane production was highest in the second cycle, the system performed better with Cu NPs on the electrodes, and microbial analysis revealed specific bacterial genera thriving in the system, particularly on cathodes with Cu NPs.
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The current study presented a novel process of biogas upgrading to biomethane (higher than 97%) based on anaerobic sludge and zero-valent iron (ZVI) system. When ZVI was added into an aquatic system with anaerobic granular sludge (AnGrSl) under anaerobic abiotic conditions, H was generated. Then, the H and CO were converted by the hydrogenotrophic methanogens to CH.

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