1,657 research outputs found

    Ceramics with photonic and optical applications

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    There is a fast growing interest in new applications for advanced ceramic systems in the field of functional materials and in particular for optical materials. Ceramics are entitled to fulfil the gap between glasses and single crystals in the area of photonic materials. The processing versatility and unpaired resistance to high temperature corrosive environments of some ceramics make them good candidates for such applications. However, the critical dependence of the material optical properties on microstructure makes the deep understanding of the processing conditions even more necessary than before for the fabrication of well ordered, transparent, efficient optical ceramics. This review is directed towards ceramists interested in new applications. In the paper we address some fundamental aspects of the relationship between processing, microstructure and optical properties that are illustrated with some examples related with transparent ceramics, glass ceramics, luminescence, random lasers, thermo-emissive applications, scintillators and dielectric metamaterials

    Directionally solidified cobalt-doped MgO-MgAl2O4 eutectic composites for selective emitters

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    Cobalt-doped MgO-MgAl2O4 eutectic composites were explored for their use as selective emitters for thermophotovoltaic devices. Eutectic ceramic rods with different cobalt content were directionally solidified by using the laser floating zone technique at two processing rates to obtain microstructures with different domain sizes. Thermal emission between 1000 °C and 1500 °C and optical properties (reflectance and transmittance) at room temperature were measured in the Co-doped composites and the effect on microstructure and cobalt content was investigated. Thermal emission consisted of an intense broad band at about 1.67 µm matching with the bandgap of the InGaAs cell. The emission was ascribed to the de-excitation from the 4T1(F) multiplet to the 4A2(F) ground state of the thermally excited Co ions located in the tetrahedral sites of the MgAl2O4 phase. The selectivity of the thermal emission showed a decrease with the cobalt content due to the enhancement of other electronic transitions, which leads to keeping the cobalt content in these composites at low levels (<0.15% at Co) for their use as selective emitters

    Ionic self-assembly of pillar[5]arenes: proton-conductive liquid crystals and aqueous nanoobjects with encapsulation properties

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    Liquid crystal (LC) pillar[n]arenes have been barely explored due to their time-consuming and complicated synthesis, despite their promising properties for metal-ion separation, drug delivery, or surface functionalization. Herein, we report an easy and reliable method to functionalize pillar[n]arene macrocycles through electrostatic interactions. These ionic materials were prepared by ionically functionalizing a pillar[n]arene containing ten amine terminal groups with six different carboxylic acids. This supramolecular approach results in ionic pillar[n]arenes which self-organize into LC phases with good proton-conducting properties. Moreover, ionic functionalization provides a new amphiphilic character to the pillar[n]arenes, which self-assemble in water to produce a variety of nanoobjects (i.e., spherical or cylindrical micelles, vesicles, solid nanospheres, or nanotubes) that are capable of encapsulating a model hydrophobic drug. Interestingly, the presence of coumarin moieties in the chemical structure of the ionic pillar[n]arenes results in self-organized materials with light-responsive properties due to the ability of coumarins to undergo photo-induced [2+2] cycloaddition. In particular, we demonstrate that coumarin pohotodimerization can be employed to fabricate mechanically stable proton-conductive LC materials, as well as to obtain photo-responsive nanocarriers with light-induced release of encapsulated molecules

    A performance evaluation of MM5/MNEQA/CMAQ air quality modelling system to forecast ozone concentrations in Catalonia

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    We examine the ability of a modelling system to forecast the formation and transport of ozoneover Catalonia, at the NE of the Iberian Peninsula. To this end, the Community MultiscaleAir Quality (CMAQ) modelling system developed by the United States Environmental ProtectionAgency (US EPA) and the PSU/NCAR mesoscale modelling system MM5 are coupled to a newemission model, the Numerical Emission Model for Air Quality (MNEQA). The outputs of themodelling system for the period from May to October 2008 are compared with ozone measure-ments at selected air-monitoring stations belonging to the Catalan Government. Results indicatea good behaviour of the model in reproducing diurnal ozone concentrations, as statistical valuesfall within the EPA and EU regulatory frameworks

    Projecte campus multimodal: pilotatge del suport de veu en lectura. Memòria final

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    El projecte va ser acceptat a la convocatòria PID 2011-2012Memòria final del projecte d'innovació docent "Campus multimodal" en el què es va experimentar amb dues eines de suport de veu en la lectura en una assignatura de Tècniques de Treball en diverses carreres associades amb Dret. Les eines van ser ClaroRead, un programari de PC que llegeix en veu alta tot el contingut de l'ordinador ressaltant la paraula llegida i amb altres utilitats de resum i creació de mapes conceptuals; i ReadSpeaker, una eina instal.lada al campus virtual que llegeix en veu alta el contingut web i contingut dels fitxers PDF. S'explica l'experiència i els resultats. Es conclou amb la necessitat de facilitar eines de suport a la lectura per als alumnes amb necessitats especials.ReadSpeaker, Integrate

    Accidentabilidad laboral con productos biológicos en profesionales sanitarios de Atención Primaria de Guadalajara (1994-2000)

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    Infections by Human Inmunodeficiency Virus (HIV),Hepatitis B Virus (HBV) and Hepatitis C virus (HCV),with important medical and social consequences, can be transmitted by contact with human fluids. Health care workers can be infected from these fluids and they can also infect their patients. The objetive of this study is to know the magnitude and distribution of occupational accidents with biological products in Primary Health Care workers and Community, in Guadalajara (Spain) and to know the transmission of these viruses between 1994 and 2000. This is neccesary to reduce infections in heath workers with Health Educacional programmes designed to reduce the number of occupational accidents.Descriptive analysis of the occupational accidents notified by Primary Care workers of Guadalajara throughout 1994-2000 period.We registered an increasing number of occupational accidents registered in the period. 71.25% of Primary Care workers have received VHB vaccination, but this percentage in doctors was only 52.9%. 45% of the workers were using protection equipment when the accidetn took place. We have not registered any infection in a worker during the period of study.Las infecciones por Virus de la Inmunodeficiencia Humana (VIH),Virus de la Hepatitis B (VHB) y Virus de la Hepatitis C (VHC), de graves consecuencias médicas y sociales, se transmiten por contacto con sangre u otros fluídos orgánicos. El personal sanitario puede infectarse mediante el contacto con fluídos corporales y también transmitir dichas infecciones a los pacientes. Los objetivos de este estudio son conocer la magnitud y distribución de la accidentabilidad laboral con productos biológicos en los trabajadores de Atención Primaria de Guadalajara, así como la magnitud de la transmisión de la infección por VIH, VHC y VHB durante un período de siete años como paso previo para intentar reducir las infecciones transmitidas a personal sanitario y para implementar políticas de educación sanitaria que reduzcan este tipo de accidentes.Se realizó un estudio descriptivo de los accidentes laborales notificados por los trabajadores de Atención Primaria de Guadalajara y Comunidad que notificaron un accidente laboral entre 1994 y 2000.Se ha objetivado un aumento en las declaraciones de accidentes laborales con productos biológicos a lo largo del tiempo. El 71.25% de los trabajadores de centros sanitarios están vacunados frente a VHB, proporción que se ve reducida al 52.9% si se considera exclusivamente al personal facultativo. La protección con equipos de protección individual se mantenía en el 45% de los trabajadores en el momento del accidente. No se ha objetivado ninguna infección en el personal sanitario ni en población general estudiada durante el período de seguimiento

    Measuring membrane permeation rates through the optical visualization of a single pore

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    Membranes are a critical technology for energy-efficient separation processes. The routine method of evaluating membrane performance is a permeation measurement. However, such measurements can be limited in terms of their utility: membrane microstructure is often poorly characterized; membranes or sealants leak; and conditions in the gas phase are poorly controlled and frequently far-removed from the conditions employed in the majority of real processes. Here, we demonstrate a new integrated approach to determine permeation rates, using two novel supported molten-salt membrane geometries. In both cases, the membranes comprise a solid support with laser-drilled pores, which are infiltrated with a highly CO2-selective molten carbonate salt. First, we fabricate an optically transparent single-crystal, single-pore model membrane by local laser drilling. By infiltrating the single pore with molten carbonate, monitoring the gas-liquid interface optically, and using image analysis on gas bubbles within the molten carbonate (because they change volume upon controlled changes in gas composition), we extract CO2 permeation rates with exceptional speed and precision. Additionally, in this arrangement, microstructural characterization is more straightforward and a sealant is not required, eliminating a major source of leakage. Furthermore, we demonstrate that the technique can be used to probe a previously unexplored driving force region, too low to access with conventional methods. Subsequently, we fabricate a leak-free tubular-supported molten-salt membrane with 1000 laser-drilled pores (infiltrated with molten carbonate) and employ a CO2-containing sweep gas to obtain permeation rates in a system that can be described with unprecedented precision. Together, the two approaches provide new ways to measure permeation rates with increased speed and at previously inaccesible conditions

    Scientific Advice on the estimation of surplus for Sustainable Fisheries Partnership Agreements.

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    Scientific advice on the concept of surplus, as defined by the UNCLOS, was provided for three types of Sustainable Fisheries Partnership Agreements (SFPAs): i) Mixed SFPAs in West Africa, ii) Tuna SFPAs and iii) SFPA with Greenland. For Mixed SFPAs in West Africa, methods for surplus computation were defined, including alternatives for cases of data limited stocks. These methods may use as input five parameters that could be obtained from those recent stocks assessments that are representative of the current stock status. Surplus estimates would need to be regularly updated (ideally, yearly), according to every new stock assessments and following the enforcement of a management plan (or, by default, according to a transition scheme towards reaching Fmsy in 2020). In the case of West African transboundary stocks, a theoretical share of the surplus could be calculated using a standard rule based on historical catches within EEZs. The Surplus concept is not applicable for Tuna SFPAs, due to the high migratory character of tuna or tuna-like species, the fact that these stocks are mostly found in areas beyond national jurisdictions, the lack of direct estimates of local abundance and impossibility to calculate the capacity of the coastal States. For the SFPA with Greenland, Surplus is considered as any TAC allocated to Greenland and not utilised by this coastal State
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