Scavenging activity of Magnéli phases as a function of Ti(4+)/Ti(3+) ratios

TiO2 is able to scavenge reactive oxygen and nitrogen species (ROS and RNS) in the absence of light. The scavenging mechanism has been related to the chemistry of defects (oxygen vacancy reduced oxidation states of Ti) but it is still unknown. This study describes the ROS scavenging activity of different titanium oxide phases and relates their scavenging activities with the Ti4+/Ti3+ molar ratio as well as the band gap value. The Ti5O9 phase, with a mixture of both oxidation states, presented a substantially higher percentage of 2,2-diphenyl-1-picrylhydracyl radicals (DPPH) eliminated per m2 of specific surface area in comparison to phases with predominant oxidation states Ti4+ or Ti3+ such as TiO2 and Ti2O3, respectively. The obtained results indicate that the DPPH scavenging mechanism corresponds to a catalytic process on the Ti5O9 surface which is facilitated by the presence of charges that can easily move through the material. The mobility of charges and electrons in the semiconductor surface, related to the presence of oxidation states Ti4+ and Ti3+ and a small band gap, could create an attractive surface for radical species such as DPPH. This puts forward Ti5O9 as a promising candidate coating for implantable biomedical devices, as an electrode, since it can cushion inflammatory processes which could lead to device encapsulation and, consequently, failure.The authors would like to thank the Fundación General CSIC and Obra Social “La Caixa” (Project BIOAMD) for providing financial support to this work. Dr Canillas acknowledges the financial support received from the CSIC for her PhD JAEpre grant and Dr Moreno is grateful to the Fondo Social Europeo and CSIC for her JAEDoc contract

Properties of LZS/nanoAl2O3 glass-ceramic composites

[EN] The LZS glass-ceramic (19.58 Li2O center dot 11.10ZrO(2)center dot 69.32SiO(2)) have a high coefficient thermal expansion (CTE) which can be a limitation in some applications. The addition of alumina in a LZS glass-ceramic matrix is able to reduce the CTE significantly. This happens because of the alumina affinity with respect to lithium silicates to form beta-spodumene (LiAlSi2O6), a crystalline phase having a CTE nearly zero (0.9 x 10(-6) degrees C-1).In this work, (1-5 vol%) Al2O3 nanoparticles (13 nm) were added to a LZS (3.5 mu m) glass-ceramic matrix to prepare composites with the main goal of evaluation the influence of Al2O3 on their mechanical, thermal and electrical properties. Each composition was wet homogenized and then dried at 110 degrees C for 48 h for disaggregation. The composites, sintered at 900 degrees C for 30 min, with relative densities between 92% and 98%, showed zircon and beta-spodumene as main crystalline phases. The incorporation of increasing additions of nanosized alumina progressively decreases the final density. This makes the properties to slightly decrease, also. The Young's modulus significantly decreases from 111 to 78 GPa of hardness due to the exponential variation with porosity, but the changes of toughness and hardness are much lower. The electrical conductivity was maintained within +/- 10-7 S. cm(-1), and the dielectric constant ranged from 5 to 6 for all compositions. Thermal conductivity ranged around 4.2 to 3.5 W/mK. (C) 2017 Elsevier B.V. All rights reserved.This work has been supported by CAPES in the frame of the International Cooperation Program Science without Borders for Special Visiting Researcher PVE (MEC/MCTI/CAPES/CNPq/FAPs/ No 71/2013), Project No A011/2013 (Brazil) and CNPq (National Council for Scientific and Technological Development, Brazil). This work has been also supported by Ministerio de Economia y Cornpetitividad and FEDER Funds under grant No MAT2016-67586-C3-R and grant ENE2013-49111-C2-1-R. A. Borrell acknowledges the MINECO for her Juan de la Cierva-Incorporacion contract (IJCI-2014-19839).Arcaro, S.; Moreno, B.; Chinarro, E.; Salvador Moya, MD.; Borrell Tomás, MA.; Nieto, M.; Moreno, R.... (2017). Properties of LZS/nanoAl2O3 glass-ceramic composites. Journal of Alloys and Compounds. 710:567-574. https://doi.org/10.1016/j.jallcom.2017.03.299S56757471

Around the Clock Observations of the Q0957+561 A,B Gravitationally Lensed Quasar II: Results for the second observing season

We report on an observing campaign in March 2001 to monitor the brightness of the later arriving Q0957+561 B image in order to compare with the previously published brightness observations of the (first arriving) A image. The 12 participating observatories provided 3543 image frames which we have analyzed for brightness fluctuations. From our classical methods for time delay determination, we find a 417.09 +/- 0.07 day time delay which should be free of effects due to incomplete sampling. During the campaign period, the quasar brightness was relatively constant and only small fluctuations were found; we compare the structure function for the new data with structure function estimates for the 1995--6 epoch, and show that the structure function is statistically non-stationary. We also examine the data for any evidence of correlated fluctuations at zero lag. We discuss the limits to our ability to measure the cosmological time delay if the quasar's emitting surface is time resolved, as seems likely.Comment: AAS LaTeX, 5 PostScript figure

Around-the-clock observations of the Q0957+561A,B gravitationally lensed quasar. II. Results for the second observing season

We report on an observing campaign in 2001 March to monitor the brightness of the later arriving Q0957+561B image in order to compare with the previously published brightness observations of the (first-arriving) A image. The 12 participating observatories provided 3543 image frames, which we have analyzed for brightness fluctuations. From our classical methods for time-delay determination, we find a 417.09 ± 0.07 day time delay, which should be free of effects due to incomplete sampling. During the campaign period, the quasar brightness was relatively constant and only small fluctuations were found; we compare the structure function for the new data with structure function estimates for the 1995-1996 epoch and show that the structure function during our observing interval is unusually depressed. We also examine the data for any evidence of correlated fluctuations at zero lag. We discuss the limits of our ability to measure the cosmological time delay if the quasar's emitting surface is time resolved, as seems likely

Materials directed to implants for repairing Central Nervous System

Central Nervous System (CNS) can be damaged by a wide range of injuries and disorders which entail permanent disability in some cases. Moreover, CNS repairing process presents some complications. The natural repair mechanism, which consists on the glial scar formation, is triggered by the inflammatory process. Molecules delivered during these processes, inflammation and glial scar formation as well as oxygen and glucose deficiencies due to the injury, create an inhibitory environment for axon regeneration and remyelination which is known as “secondary injury”. Biomaterials are taking up an even more important role in repairing CNS. Physicochemical properties of some ceramic materials have inspired different applications to repair CNS as substrates, electrodes or molecule vehicles. Based on their biocompatibility, capability to neutralize reactive species involved in the inflammatory processes and their versatile processing to obtain scaffolds with different shapes and sizes, ceramics are a succulent offer in nervous tissue engineering. Furthermore, their possibilities have been increased with polymeric-ceramics composites development, which have given rise to new interesting horizon.Existen diferentes tipos de lesiones o desordenes del Sistema Nervioso Central (SNC) que pueden provocar graves secuelas e incluso en algunos casos una discapacidad permanente. Además, el proceso de reparación del SNC tiene algunas complicaciones. El mecanismo natural de reacción a una lesión, el cual consiste en la formación de una cicatriz glial, es desencadenado por un proceso inflamatorio. Las moléculas liberadas durante estos procesos, la inflamación y formación de la cicatriz glial, así como la deficiencia en oxígeno y glucosa debidos a la lesión, crean un ambiente que inhibe la regeneración axonal creando la llamada “lesión secundaria”. Los biomateriales están adquiriendo un papel cada vez más importante en la reparación de SNC. Las propiedades físicoquímicas de algunos materiales han inspirado el uso de los mismos en diferentes aplicaciones para la reparación del SNC como sustratos, electrodos o moléculas transportadoras. En base a su biocompatibilidad, capacidad de neutralizar especies reactivas implicadas en el proceso inflamatorio y a la gran cantidad de posibilidades del procesamiento para obtener andamiajes con diferentes formas y tamaños, los materiales cerámicos suponen una suculenta oferta en la ingeniería del tejido nervioso. Además sus posibilidades han aumentado con el desarrollo de composites polimérico-cerámicos, los cuales ha abierto un nuevo e interesante horizonte en la materia

Electrical behaviour of ceramic breeder blankets in pebble form after γ-radiation

Lithium orthosilicate (Li4SiO4) ceramics in from of pebble bed is the European candidate for ITER testing HCPB (Helium Cooled Pebble Bed) breeding modules. The breeder function and the shielding role of this material, represent the areas upon which attention is focused. Electrical measurements are proposed for monitoring the modification created by ionizing radiation and at the same time provide information on lithium movement in this ceramic structure. The electrical tests are performed on pebbles fabricated by Spray-dryer method before and after gamma-irradiation through a 60Co source to a fluence of 4.8 Gy/s till a total dose of 5 ∗ 105 Gy. The introduction of thermal annealing treatments during the electrical impedance spectroscopy (EIS) measurements points out the recombination effect of the temperature on the γ-induced defects

Una revisión del uso del TiO₂ en terapias e ingeniería tisular

Titanium dioxide is considered a multifuctional biomaterial with long established application on bone reemplacement. Nevertheless, this oxide, due to its unique properties, has shown a potential use in new areas of biomedicine as tissue engineering. This review shows new applications of TiO2-x, based on the study of its interaction with different cell types. Those physico-chemical properties that can explain the nature of its exceptional biocompatibility are studied, demonstrating the suitability of the TiO2-x substrata for the adhesion, growth and development of hepatic, endothelial and neural cells.El óxido de titanio es considerado un biomaterial multifuncional con una experimentada aplicación en el reemplazo óseo. Sin embargo, gracias a sus propiedades, en los últimos años se ha demostrado la viabilidad de este óxido en nuevas áreas de la biomedicina, como es la ingeniería de tejidos. En esta revisión se pretenden exponer nuevas aportaciones del TiO2-x en su interacción con diferentes tipos celulares, revisando aquellas características físico-químicas del material que pueden explicar la naturaleza de su elevada biocompatibilidad. Se demuestra la idoneidad del TiO2-x como sustrato para el crecimiento de células hepáticas, endoteliales vasculares o neuronales