Dielectrical Properties of CeO2 Nanoparticles at Different Temperatures

A template-free precipitation method was used as a simple and low cost method for preparation of CeO2 nanoparticles. The structure and morphology of the prepared nanoparticle samples were studied in detail using X-ray diffraction, Raman spectroscopy and Scanning Electron Microscopy (SEM) measurements. The whole powder pattern modelling (WPPM) method was applied on XRD data to accurately measure the crystalline domain size and their size distribution. The average crystalline domain diameter was found to be 5.2 nm, with a very narrow size distribution. UV-visible absorbance spectrum was used to calculate the optical energy band gap of the prepared CeO2 nanoparticles. The FT-IR spectrum of prepared CeO2 nanoparticles showed absorption bands at 400 cm(-1) to 450 cm(-1) regime, which correspond to CeO2 stretching vibration. The dielectric constant (er) and dielectric loss (tan delta) values of sintered CeO2 compact consolidated from prepared nanoparticles were measured at different temperatures in the range from 298 K (room temperature) to 623 K, and at different frequencies from 1 kHz to 1 MHz

Hydroxyapatite and chloroapatite derived from sardine by-products

In this paper, phosphate-based compounds used in biomedicine were extracted from bones and scales of European sardines (Sardina pilchardus); this is the first time that different parts of the same fish are used for the extraction of these kinds of materials. The bones and scales behave very differently with processing, producing different materials when annealed between 600 and 1000 °C. The bones formed a mixture of hydroxyapatite (Ca10(PO 4)6(OH)2, HAp) and β-tri-calcium phosphate (β-Ca3(PO4)2, β-TCP), with a higher content of β-TCP obtained with increasing temperature. This bi-phasic material has a high added value, as it is employed as a bioceramic; in fact HAp has good biocompatibility while β-TCP has better resorbability than HAp, despite being less biocompatible. With scales, on the other hand, either a HAp-based material or a chlorine-substitute HAp containing material (chloroapatite (Ca10(PO4)6Cl2, ClAp) were produced. HAp-based material was obtained with a simple annealing process; for ClAp, on the other hand, a combined washing-annealing process was used. ClAp is also used in biomedicine, due to its improved resorption, mechanical properties and bioactivity. This is the first time ClAp of marine origin was produced. © 2014 Elsevier Ltd and Techna Group S.r.l

Hydroxyapatite and chloroapatite derived from sardine by-products

In this paper, phosphate-based compounds used in biomedicine were extracted from bones and scales of European sardines (Sardina pilchardus); this is the first time that different parts of the same fish are used for the extraction of these kinds of materials. The bones and scales behave very differently with processing, producing different materials when annealed between 600 and 1000 degrees C. The bones formed a mixture of hydroxyapatite (Ca-10(PO4)(6)(OH)(2), HAp) and beta-tri-calcium phosphate (beta-Ca-3(PO4)(2), beta-TCP), with a higher content of beta-TCP obtained with increasing temperature. This bi-phasic material has a high added value, as it is employed as a bioceramic; in fact HAp has good biocompatibility while beta-TCP has better resorbability than HAp, despite being less biocompatible. With scales, on the other hand, either a HAp-based material or a chlorine-substitute HAp containing material (chloroapatite (Ca-10(PO4)(6)Cl-2, ClAp) were produced. HAp-based material was obtained with a simple annealing process; for ClAp, on the other hand, a combined washing-annealing process was used. ClAp is also used in biomedicine, due to its improved resorption, mechanical properties and bioactivity. This is the first time ClAp of marine origin was produced. (C) 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved

Functionalised exposed building materials: Self-cleaning, photocatalytic and biofouling abilities

With the advent of urbanisation, there was a considerable and progressive worsening of urban air quality. Amongst the solutions proposed by scientific research, photocatalysis proved itself to be one of the most promising. In the present work, commercial glazed ceramic tiles were functionalised with a micrometric TiO2 layer adopting an industrial-like process. It was purposely chosen to avoid the use of nanoparticles because they might be inhaled and come into direct contact with the cells of the human organism during the industrial processing. Additionally, the self-cleaning, photocatalytic – the former by means of liquid-solid phase photocatalytic tests and water contact angle measurements; the latter against nitrogen oxides abatement – and biofouling abilities of the functionalised materials were thoroughly investigated. Results showed that the functionalised glazed ceramic tile possessed excellent self-cleaning and photocatalytic properties. As per the algal growth, surface roughness showed itself to be a key-point: the TiO2 surface layer, giving the material a higher surface roughness compared to the untreated one, had an accelerated algal growth proces

Light induced antibacterial activity and photocatalytic properties of Ag/Ag3PO4 -based material of marine origin

Fish bones were converted into materials consisting of silver phosphate (Ag3PO4), beta-calcium phosphate (beta-Ca-3(PO4)(2), beta-TCP) and hydroxyapatite (Ca-10(PO4)(6)(OH)(2), HAp), as well as of metallic silver (Ag-0), with a simple treatment in solution and calcination (650 or 1000 degrees C). The antibacterial activity of the material was measured in the dark and under UV and white light irradiation; this is the first time that an Ag3PO4-based material was tested under these conditions. Results showed light-enhanced antibacterial properties toward Gram-positive and Gram-negative strains (Methicillin-resistant Staphylococcus aureus -MRSA, Escherichia coli,Pseudomonas aeruginosa), with inactivation rates of up to 99.999% under UV light, and 99% for E. coli under white light (artificial indoor lighting). The photocatalytic activity was also tested, and the degradation of methylene blue dye was observed under both UV and white light. Even if the MB degradation was to a smaller extent under white light, it was approximately twice that of the commercial photocatalyst P25. This work demonstrates the valorisation of a food industry by-product such as fish bones to form a potentially valuable material, with important applications in self sterilizing surfaces and environmental remediation. (C) 2014 Published by Elsevier B.V

Light induced antibacterial activity and photocatalytic properties of Ag/3PO4 -based material of marine origin

Fish bones were converted into materials consisting of silver phosphate (Ag3PO4), β-calcium phosphate (β-Ca3(PO4)2, β-TCP) and hydroxyapatite (Ca10(PO4)6(OH)2, HAp), as well as of metallic silver (Ag0), with a simple treatment in solution and calcination (650 or 1000°C). The antibacterial activity of the material was measured in the dark and under UV and white light irradiation; this is the first time that an Ag3PO4-based material was tested under these conditions. Results showed light-enhanced antibacterial properties toward Gram-positive and Gram-negative strains (Methicillin-resistant Staphylococcus aureus - MRSA, Escherichia coli, Pseudomonas aeruginosa), with inactivation rates of up to 99.999% under UV light, and 99% for E. coli under white light (artificial indoor lighting). The photocatalytic activity was also tested, and the degradation of methylene blue dye was observed under both UV and white light. Even if the MB degradation was to a smaller extent under white light, it was approximately twice that of the commercial photocatalyst P25. This work demonstrates the valorisation of a food industry by-product such as fish bones to form a potentially valuable material, with important applications in self sterilizing surfaces and environmental remediation

The influence of TiO2 nanoparticles and poliacrilonitrile fibers on the rheological behavior and hardened properties of mortars

This experimental research evaluates the individual and combined influence of poliacrilonitrile (PAN) fibers and nanoTiO(2) (nT) particles on the fresh and hardened properties of mortars up to 28 days. Samples with 0-0.125 wt% PAN, 0-1.0 wt% nT and 0.83-0.87 W/B were prepared. Samples with similar workability showed distinct rheological behavior along time and the yield stress was the best rheological parameter to represent such variations. The very high specific surface area and wettability of nT was dominant over the one induced by PAN fibers and severely limited the rheological behavior maintenance up to 0.050PAN + 1.00nT sample. The physical properties (apparent density, water absorption, apparent porosity) indicate that PAN is dependent on the correct correlation with nT particles. In addition, the optimal concentration of PAN is about 0.05 wt% to the flexural and compressive strength, while the most active NOx degradation reached similar to 77% to those containing 1 wt% nT, regardless the concentration of PAN. (C) 2014 Elsevier Ltd. All rights reserved