Potential reactivity of the andesitic rocks from Cabo de Gata (SE Spain)

8 páginas, 4 figuras, 3 tablas.[ES] Las rocas andesíticas producen una reacción álcalis-sílice con los componentes de la fase intersticial del hormigón. Esta reacción puede encuadrarse dentro de las de cinética lenta, ya que la disolución incongruente de los minerales constituyentes de las rocas, da lugar a la formación tardía de geles silicocalco- alcalinos. En consecuencia, la utilización convencional del método de ensayo de barras de mortero no detecta la reacción hasta transcurridos al menos 90 días.[EN] Andesitic rocks produce an alkali-silica reaction with the components of the interstitial phase of concrete. This reaction can be considered as belonging to the slow-kinetic type, since the incongruent dissolution of the rock-forming minerals leads to the late formation of siliceous calc-alkaline gel. As a conquence, the conventional mortar-bar method does not detect such reaction until 90 days later.Peer reviewe

Periodic venting of MABR lumen allows high removal rates and high gas-transfer efficiencies

The membrane-aerated biofilm reactor (MABR) is a novel treatment technology that employs gas-supplying membranes to deliver oxygen directly to a biofilm growing on the membrane surface. When operated with closed-end membranes, the MABR provides 100-percent oxygen transfer efficiencies (OTE), resulting in significant energy savings. However, closed-end MABRs are more sensitive to back-diffusion of inert gases, such as nitrogen. Back-diffusion reduces the average oxygen transfer rates (OTR), consequently decreasing the average contaminant removal fluxes (J). We hypothesized that venting the membrane lumen periodically would increase the OTR and J. Using an experimental flow cell and mathematical modeling, we showed that back-diffusion gas profiles developed over relatively long timescales. Thus, very short ventings could re-establish uniform gas profiles for relatively long time periods. Using modeling, we systematically explored the effect of the venting interval (time between ventings). At moderate venting intervals, opening the membrane for 20 s every 30 min, the venting significantly increased the average OTR and J without substantially impacting the OTEs. When the interval was short enough, in this case shorter than 20 min, the OTR was actually higher than for continuous open-end operation. Our results show that periodic venting is a promising strategy to combine the advantages of open-end and closed end operation, maximizing both the OTR and OTE.Primary funding for this work was from Water Environment Research Foundation (WERF) project U2R14. Additional funding was provided by the Basque Government, partially financing Patricia Pérez, and the Spanish Ministry of Economics and Competitiveness and the European Regional Development Fund (FEDER), project “Innovative Integrated Biological Processes for Nutrients Removal (PBi2)” (CTM2012-36227)

Oxygen photo-adsorption related quenching of photoluminescence in group-III nitride nanocolumns

GaN and InGaN nanocolumns of various compositions are studied by room-temperature photoluminescence (PL) under different ambient conditions. GaN nanocolumns exhibit a reversible quenching upon exposure to air under constant UV excitation, following a t−1/2 time dependence and resulting in a total reduction of intensity by 85–90%, as compared to PL measured in vacuum, with no spectral change. This effect is not observed when exposing the samples to pure nitrogen. We attribute this effect to photoabsorption and photodesorption of oxygen that modifies the surface potential bending. InGaN nanocolumns, under the same experimental conditions do not show the same quenching features: The high-energy part of the broad PL line is not modified by exposure to air, whereas a lower-energy part, which does quench by 80–90%, can now be distinguished. We discuss the different behaviors in terms of carrier localization and possible composition or strain gradients in the InGaN nanocolumns

A strategic reflection for the management and implementation of CAR-T therapy in Spain: an expert consensus paper

CAR-T cell therapy represents a therapeutic revolution in the prognosis and treatment of patients with certain types of hematological cancer. However, they also pose new challenges in the healthcare, regulatory and financial fields. The aim of the RET-A project was to undertake a strategic reflection on the management of CAR-T therapies within the Spanish National Health System, to agree on recommendations that will help to better deal with the new context introduced by these cell therapies in the present and in the future. This think tank involved 40 key agents and opinion leaders. The experts identified three great challenges for implementing advanced therapies in Spain: therapeutic individualisation, with a multidisciplinary approach; acceleration of access times, by minimizing bureaucracy; and increase in the number of centers qualified to manage the CAR-T therapies in the NHS. The experts agreed on the ideal criteria for designating those qualified centers. They also agreed on a comprehensive CAR-T care pathway with the timings and roles which would ideally be involved in each part of the process.This study was funded by Gilead Sciences, Inc.Peer reviewe

Evaluación de la reactividad árido-álcali en diversos áridos silicatados. Alternativas para minimizar esta reacción

Siliceous aggregates are characterized for presenting certain chemical reactivity opposite to the calcium hydroxide liberated in the hydration of the Portland cement. The consequence of this reaction between the aggregate and the components of the intermediate concrete phase is the formation of gels very eager for water that can generate important disruptive pressures in the deeper structure of concrete. We have assessed the potential reactivity of several siliceous aggregates (granites, gneiss, hornfels, granites, quartzite and serpentine) by means of the accelerated method in concrete bars (normalized method) and the superficial reactivity method, observing by scanning electron microscopy (SEM) the formation of silica calcium alkaline gels. On the other hand, we explore the way of minimizing this disruptive reaction employing ground clay bricks and cement type CEM IV UNE-EN 197-1.Los áridos silíceos se caracterizan por reaccionar con el hidróxido cálcico liberado en el proceso de hidratación del cemento, lo que debido a su elevada avidez por el agua genera geles expansivos, que provocan importantes tensiones disruptivas en el seno del hormigón. En este trabajo hemos evaluado la reactividad potencial de varios áridos silíceos (granitos, gneis, corneanas, granitos, cuarcita y serpentina) mediante el método acelerado de barras de mortero (normalizado), y el método de reactividad superficial, observando los geles silicocalcoalcalinos formados mediante microscopía electrónica de barrido (SEM). Por otra parte, aportamos dos vías de minimización de esta reacción disruptiva, empleando ladrillo cerámico molido en un caso, y cemento CEM IV UNE-EN 197-1 en el otro

Effect of different buffer layers on the quality of InGaN layers grown on Si

This work studies the effect of four different types of buffer layers on the structural and optical properties of InGaN layers grown on Si(111) substrates and their correlation with electrical characteristics. The vertical electrical conduction of n-InGaN/buffer-layer/p-Si heterostructures, with In composition near 46%, which theoretically produces an alignment of the bands, is analyzed. Droplet elimination by radical-beam irradiation was successfully applied to grow high quality InGaN films on Si substrates for the first time. Among several buffer choices, an AlN buffer layer with a thickness above 24 nm improves the structural and optical quality of the InGaN epilayer while keeping a top to bottom ohmic behavior. These results will allow fabricating double-junction InGaN/Si solar cells without the need of tunnel junctions between the two sub-cells, therefore simplifying the device design

Emission polarization control in semiconductor quantum dots coupled to a photonic crystal microcavity

8 páginas, 5 figuras.-- OCIS codes: (160.4760) Optical properties; (230.5298) Photonic crystals; (230.5590) Quantumwell, -wire and –dot devices.We study the optical emission of single semiconductor quantum dots weakly coupled to a photonic-crystal micro-cavity. The linearly polarized emission of a selected quantum dot changes continuously its polarization angle, from nearly perpendicular to the cavity mode polarization at large detuning, to parallel at zero detuning, and reversing sign for negative detuning. The linear polarization rotation is qualitatively interpreted in terms of the detuning dependent mixing of the quantum dot and cavity states. The present result is relevant to achieve continuous control of the linear polarization in single photon emitters.This work has been supported by research contracts of the Spanish Ministry of Education Grants MAT2008-01555/NAN, Consolider CSD 2006-19 and Naninpho-QD TEC2008-06756-C03- 01, and the Community of Madrid Grant Grant CAM (S2009/ESP-1503).Peer reviewe