Dioxouranium(VI) extraction in microchannels using ionic liquids

The extraction of uranium(VI) from aqueous nitric acid solutions by tributylphosphate {TBP; 30%(v/v)} dissolved in the ionic liquid 1-butyl-3-methylimidazolium bis{(trifluoromethyl)sulfonyl}amide was investigated. The experiments were performed in a Teflon microchannel of 0.5 mm internal diameter, while the dioxouranium(VI) concentrations in the aqueous and the ionic liquid phases were determined by UV-Vis spectroscopy. The effects of initial nitric acid concentration (0.01-3 M), residence time, and phase flow rate ratio were studied. It was found that, with increasing nitric acid concentration, the percentage of dioxouranium(VI) extracted decreased and then increased again, while the extraction efficiency followed a slightly different trend. Overall mass transfer coefficients varied between 0.049 s and 0.312 s . © 2012 Elsevier B.V. All rights reserved.

Electrochemical sensor for catechol and dopamine based on a catalytic molecularly imprinted polymer-conducting polymer hybrid recognition element

One of the difficulties with using molecularly imprinted polymers (MIPs) and other electrically insulating materials as the recognition element in electrochemical sensors is the lack of a direct path for the conduction of electrons from the active sites to the electrode. We have sought to address this problem through the preparation and characterization of novel hybrid materials combining a catalytic MIP, capable of oxidizing the template, catechol, with an electrically conducting polymer. In this way a network of "molecular wires" assists in the conduction of electrons from the active sites within the MIP to the electrode surface. This was made possible by the design of a new monomer that combines orthogonal polymerizable functionality; comprising an aniline group and a methacrylamide. Conducting films were prepared on the surface of electrodes (Au on glass) by electropolymerization of the aniline moiety. A layer of MIP was photochemically grafted over the polyaniline, via N,N'-diethyldithiocarbamic acid benzyl ester (iniferter) activation of the methacrylamide groups. Detection of catechol by the hybrid-MIP sensor was found to be specific, and catechol oxidation was detected by cyclic voltammetry at the optimized operating conditions: potential range -0.6 V to +0.8 V (vs Ag/AgCl), scan rate 50 mV/s, PBS pH 7.4. The calibration curve for catechol was found to be linear to 144 µM, with a limit of detection of 228 nM. Catechol and dopamine were detected by the sensor, whereas analogues and potentially interfering compounds, including phenol, resorcinol, hydroquinone, serotonin, and ascorbic acid, had minimal effect (=3%) on the detection of either analyte. Nonimprinted hybrid electrodes and bare gold electrodes failed to give any response to catechol at concentrations below 0.5 mM. Finally, the catalytic properties of the sensor were characterized by chronoamperometry and were found to be consistent with Michaelis-Menten kinetics. © 2009 American Chemical Society.

Studies of the Room-Temperature Multiferroic Pb(Fe>0.5>Ta>0.5>)>0.4>(Zr>0.53>Ti>0.47>)>0.6>O>3>: Resonant Ultrasound Spectroscopy, Dielectric, and Magnetic Phenomena

Recently, lead iron tantalate/lead zirconium titanate (PZTFT) was demonstrated to possess large, but unreliable, magnetoelectric coupling at room temperature. Such large coupling would be desirable for device applications but reproducibility would also be critical. To better understand the coupling, the properties of all 3 ferroic order parameters, elastic, electric, and magnetic, believed to be present in the material across a range of temperatures, are investigated. In high temperature elastic data, an anomaly is observed at the orthorhombic mm2 to tetragonal 4mm transition, Tot = 475 K, and a softening trend is observed as the temperature is increased toward 1300 K, where the material is known to become cubic. Thermal degradation makes it impos- sible to measure elastic behavior up to this temperature, however. In the low temperature region, there are elastic anomalies near ≈40 K and in the range 160–245 K. The former is interpreted as being due to a magnetic ordering transition and the latter is interpreted as a hysteretic regime of mixed rhom- bohedral and orthorhombic structures. Electrical and magnetic data collected below room temperature show anomalies at remarkably similar temperature ranges to the elastic data. These observations are used to suggest that the three order parameters in PZTFT are strongly coupled.

One-dimensional porous La>0.5>Sr>0.5>CoO>2.91> nanotubes as a highly efficient electrocatalyst for rechargeable lithium-oxygen batteries

>The electrochemical performance of one-dimensional porous La>0.5>Sr>0.5>CoO>2.91> nanotubes as a cathode catalyst for rechargeable nonaqueous lithium-oxygen (Li-O>2>) batteries is reported here for the first time. In this study, one-dimensional porous La>0.5>Sr>0.5>CoO>2.91> nanotubes were prepared by a simple and efficient electrospinning technique. These materials displayed an initial discharge capacity of 7205 mAh g>-1> with a plateau at around 2.66 V at a current density of 100 mA g>-1>. It was found that the La>0.5>Sr>0.5>CoO>2.91> nanotubes promoted both oxygen reduction and oxygen evolution reactions in alkaline media and a nonaqueous electrolyte, thereby improving the energy and coulombic efficiency of the Li-O>2> batteries. The cyclability was maintained for 85 cycles without any sharp decay under a limited discharge depth of 1000 mAh g>-1>, suggesting that such a bifunctional electrocatalyst is a promising candidate for the oxygen electrode in Li-O>2> batteries.>

Investigation into the effect of molybdenum-site substitution on the performance of Sr>2>Fe>1.5>Mo>0.5>O>6-δ >for intermediate temperature solid oxide fuel cells

>In this paper, niobium doping is evaluated as a means of enhancing the electrochemical performance of a Sr>2>Fe>1.5>Mo>0.5>O>6-δ> (SFM) perovskite structure cathode material for intermediate temperature solid oxide fuel cells (IT-SOFCs) applications. As the radius of Nb approximates that of Mo and exhibits +4/+5 mixed valences, its substitution is expected to improve material performance. A series of Sr>2>Fe>1.5>Mo>0.5-x>Nb>x>O>6-δ> (x = 0.05, 0.10, 0.15, 0.20) cathode materials are prepared and the phase structure, chemical compatibility, microstructure, electrical conductivity, polarization resistance and power generation are systematically characterized. Among the series of samples, Sr>2>Fe>1.5>Mo>0.4>Nb>0.10>O>6-δ> (SFMNb>0.10>) exhibits the highest conductivity value of 30 S cm>-1> at 550°C, and the lowest area specific resistance of 0.068 Ω cm>2> at 800°C. Furthermore, an anode-supported single cell incorporating a SFMNb>0.10> cathode presents a maximum power density of 1102 mW cm>-2> at 800°C. Furthermore no obvious performance degradation is observed over 15 h at 750°C with wet H>2>(3% H>2>O) as fuel and ambient air as the oxidant. These results demonstrate that SFMNb shows great promise as a novel cathode material for IT-SOFCs.>

Investigation into the effect of Fe-site substitution on the performance of Sr>2>Fe>1.5>Mo>0.5>O>6-δ >anodes for SOFCs

>Ni-substituted Sr>2>Fe>1.5-x>Ni>x>Mo>0.5>O>6-δ> (SFNM) materials have been investigated as anode catalysts for intermediate temperature solid oxide fuel cells. Reduced samples (x = 0.05 and 0.1) maintained the initial perovskite structure after reduction in H>2>, while metallic nickel particles were detected on the grain surface for x = 0.2 and 0.3 using transmission electron microscopy. Temperature programmed reduction results indicate that the stable temperature for SFNM samples under reduction conditions decreases with Ni content. In addition, X-ray photoelectron spectroscopy analysis suggests that the incorporation of Ni affects the conductivity of SFNM through changing the ratios of Fe>3+>/Fe>2+> and Mo>6+>/Mo>5+>. Sr>2>Fe>1.4>Ni>0.1>Mo>0.5>O>6-δ> shows the highest electrical conductivity of 20.6 S cm>-1> at 800 °C in H>2>. The performance of this anode was further tested with electrolyte-supported cells, giving 380 mW cm>-2> at 750 °C in H>2>, hence demonstrating that Ni doping in the B-site is beneficial for Sr>2>Fe>1.5>Mo>0.5>O>6-δ> anode performance. >

Characterisation of a two-dimensional liquid-filled ion chamber detector array using flattened and unflattened beams for small fields, small MUs and high dose-rates

In this study, the PTW 1000SRS array with Octavius 4D phantom was characterised for FF and FFF beams. MU linearity, field size, dose rate, dose per pulse (DPP) response and dynamic conformal arc treatment accuracy of the 1000SRS array were assessed for 6MV, 6FFF and 10FFF beams using a Varian TrueBeam STx linac. The measurements were compared with a pinpoint IC, microdiamond IC and EBT3 Gafchromic film. Measured dose profiles and FWHMs were compared with film measurements. Verification of FFF volumetric modulated arc therapy (VMAT) clinical plans were assessed using gamma analysis with 3%/3 mm and 2%/2 mm tolerances (10% threshold). To assess the effect of cross calibration dose rate, clinical plans with different dose rates were delivered and analysed. Output factors agreed with film measurements to within 4.5% for fields between 0.5 and 1 cm and within 2.7% for field sizes between 1.5 and 10 cm and were highly correlated with the microdiamond IC detector. Field sizes measured with the 1000SRS array were within 0.5 mm of film measurements. A drop in response of up to 1.8%, 2.4% and 5.2% for 6MV, 6FFF and 10FFF beams respectively was observed with increasing nominal dose rate. With an increase in DPP, a drop of up to 1.7%, 2.4% and 4.2% was observed in 6MV, 6FFF and 10FFF respectively. The differences in dose following dynamic conformal arc deliveries were less than 1% (all energies) from calculated. Delivered VMAT plans showed an average pass percentage of 99.5(±0.8)% and 98.4(±3.4)% with 2%/2 mm criteria for 6FFF and 10FFF respectively. A drop to 97.7(±2.2)% and 88.4(±9.6)% were observed for 6FFF and 10FFF respectively when plans were delivered at the minimum dose rate and calibrated at the maximum dose rate. Calibration using a beam with the average dose rate of the plan may be an efficient method to overcome the dose rate effects observed by the 1000SRS array.

O uso do software de edição áudio Audacity 2.0.5: aprendizagens decorrentes da sua utilização

Contém CD com áudio como anexo

Selective N-monomethylation of aniline over Zn1-xNixFe2O4 (x=0, 0.2, 0.5, 0.8 and 1) type systems

The reaction of aniline with methanol was carried out over Zn1-xNixFe2O4 (x= 0, 0.2, 0.5, 0.8 and 1) type systems in a fixed-bed down-flow reactor. It was observed that systems possessing low ``x'' values are highly selective and active for mono N-alkylation of aniline leading to N-methyl aniline. Selectivity for N-methyl aniline over ZnFe2O4 was more than 99% under the optimized reaction conditions. Even at methanol to aniline molar ratio of 2, the yield of N-methyl aniline was nearly 55.5%, whereas its yield exceeded 67% at the molar ratio of 7. The Lewis acid sites of the catalysts are mainly responsible for the good catalytic performance. Cation distribution in the spinel lattice influences their acido-basic properties, and hence, these factors have been considered as helpful to evaluate the activity and stability of the systems.

Selective N-monomethylation of aniline using Zn1-x CoxFe2O4( x=0, 0.2, 0.5, 0.8 and 1.0)type systems

A series of ferrites having the general formula Zn1-xCoxFe2O4 (x=0, 0.2, 0.5, 0.8 and 1.0)were prepared by soft chemical route. The materials were characterized by adopting various physico-chemical methods. The reaction of aniline with methanol was studied in a fixed-bed reactor system as a potential source for the production of various methyl anilines. It was observed that systems possessing low ‘ x’ values are highly selective and active for N-monoalkylation of aniline leading to N-methylaniline. Reaction parameters were properly varied to optimize the reaction conditions for obtaining N-methylaniline selectively and in better yield. Among the systems Zn0.8Co0.2Fe2O4 is remarkable due to its very high activity and excellent stability. Under the optimized conditions N-methylaniline selectivity exceeded 98%. Even at a methanol to aniline molar ratio of 2, the yield of N-methylaniline was nearly 50%, whereas its yield exceeded 71% at the molar ratio of 5. ZnFe2O4, though executed better conversion than Zn0.8Co0.2Fe2O4 in the initial period of the run, deactivates quickly as the reaction proceeds. The Lewis acidity of the catalysts is mainly responsible for the good performance. Cation distribution in the spinel lattice influences their acido-basic properties and, hence, these factors have been considered as helpful parameters to evaluate the activity of the systems.

Study of cyclohexanol decomposition reaction over the ferrospinels, A1−xCuxFe2O4 (A=Ni or Co and x=0, 0.3, 0.5, 0.7 and 1), prepared by ‘soft’ chemical methods

Preparation of simple and mixed ferrospinels of nickel, cobalt and copper and their sulphated analogues by the room temperature coprecipitation method yielded fine particles with high surface areas. Study of the vapour phase decomposition of cyclohexanol at 300 °C over all the ferrospinel systems showed very good conversions yielding cyclohexene by dehydration and/or cyclohexanone by dehydrogenation, as the major products. Sulphation very much enhanced the dehydration activity over all the samples. A good correlation was obtained between the dehydration activities of the simple ferrites and their weak plus medium strength acidities (usually of the Brφnsted type) determined independently by the n-butylamine adsorption and ammonia-TPD methods. Mixed ferrites containing copper showed a general decrease in acidities and a drastic decrease in dehydration activities. There was no general correlation between the basicity parameters obtained by electron donor studies and the ratio of dehydrogenation to dehydration activities. There was a leap in the dehydrogenation activities in the case of all the ferrospinel samples containing copper. Along with the basic properties, the redox properties of copper ion have been invoked to account for this added activity.

Psicopedagogía preventiva de 0-5 años.

Estudiar las características del niño de preescolar, para su completo desarrollo, planteado desde un enfoque ambiental, teniendo en cuenta factores influyentes en el proceso de maduración del niño. Se ha tenido en cuenta tres enfoques teóricos, el enfoque médico, psicológico, y pedagógico. El trabajo consta de cuatro capítulos. El primer capítulo explica las medidas preventivas que pueden tomarse antes de la concepción, durante el embarazo y en el momento del nacimiento del niño, al considerarse periodos importantes y determinantes del posterior desarrollo de éste. En el segundo capítulo hace referencia a la importancia del primer año de vida del niño: cómo deben cubrirse las necesidades biofísicas y psicológicas del niño para favorecer su maduración y el papel que desempeñan la exploración neurológica y la estimulación precoz. En el tercer capítulo trata de una forma general los proceso madurativos en el niño y como van a verse influenciados positiva o negativamente por una serie de factores, así como su repercusión en los procesos de aprendizaje. En el capítulo cuarto incluye la orientador familiar como medio para favorecer la actuación educativa de los padres, las medidas que pueden llevar a cabo la administración de un país y los centros de acción preventiva. 1) Es importante ofrecer un asesoramiento genético preconcepcional así como la detección y tratamiento precoz de enfermedades maternas que pueden afectar desfavorablemente al desarrollo, durante el periodo de gestación. 2) El estado de salud, tanto físico como emocional, de la gestante, va a condicionar la evolución del embarazo. Ante la posibilidad de que aparezcan complicaciones que puedan ser de gravedad para la madre y el futuro hijo, surge la necesidad de que éste se desarrolle dentro de unas condiciones favorables. 3) El control médico llevado a cabo en el periodo prenatal puede preveer las posibles complicaciones que surjan en el parto. 4) La observación del recién nacido durante las primeras horas de vida, facilita la detección precoz de anomalías que con el tratamiento adecuado se pueden evitar o al menos paliar sus consecuencias. 5) El primer año de vida es clave para el desarrollo posterior. 6) Una actuación psicopedagógica oportuna, con los métodos de diagnóstico y tratamiento de que disponemos y aplicados desde su nacimiento actuarán como medidas preventivas ante los trastornos que pudieran surgir con posterioridad. 7) Un objetivo esencial será conseguir una influencia favorable de todos aquellos factores que condicionan los procesos madurativos. 8) La herencia y el entorno son dos factores básicos del desarrollo. Las alteraciones de origen genético pueden corregirse con la adecuada y oportuna intervención del entorno. 9) La maduración es fundamental para el progreso del individuo. 10) El estado físico del niño repercute en su estado psicológico y en todo su proceso evolutivo. 11) La evolución psicológica del niño está determinada por la personalidad de los padres: orientándoles acerca de su actuación y prestándoles la ayuda necesaria para resolver sus conflictos mediante terapia y tratamientos adecuados, se puede evitar la influencia de personalidades paternas nocivas. 12) La administración del país debería favorecer la creación de instituciones de acción preventivas que adopten todas las medidas necesarias para que la orientación e información llegue a todos los sectores de la población.

Avaliação dos padrões de dose em radiologia pediátrica : comparação entre sistemas convencionais de películas e sistemas de digitalização de imagem em crianças dos 0-5 anos de idade, na radiografia do tórax em incidência antero-posterior

As evidências indicam que os sistemas de digitalização de imagem deveriam possibilitar uma redução da dose de radiação utilizada na execução de um determinado exame radiológico mas, na prática, nem sempre a dose utilizada é menor que em sistemas convencionais, por um lado, devido às características inerentes dos detectores utilizados e, por outro, ao papel preponderante da intervenção do Técnico de Radiologia. Pretendeu-se comparar a dose à entrada da pele (DEP) em crianças dos 0-5 anos, submetidas a radiografia do tórax, em Incidência Antero-Posterior (AP), em dois hospitais com diferentes sistemas de aquisição de imagem, comparando, também, os valores obtidos, com os níveis de referência de diagnóstico regulamentados pela ICRP. A média da dose à entrada da pele, no hospital que utiliza sistema de digitalização de imagem é de 26,64 Gy, enquanto que no hospital que utiliza sistema convencionail de películas é de 6,85 Gy. Observou-se que a média da dose à entrada da pele, nos sistemas de digitalização de imagem foram superiores à média das doses à entrada da pele nos sistemas convencionais de películas. Em ambos os hospitais a média da dose para as respectivas faixas etárias dos pacientes, não ultrapassou os limites estipulados por lei.

Protocolo de diagnóstico e intervención psicopedagógica: Guía No.1 de diagnóstico rápido; 0-5 años

La escuela en la comunidad se constituye como el espacio articulador y movilizador, pieza fundamental para la organización, la toma de decisiones y la acción transformadora. El proceso de aprendizaje por ende debe ser comprendido desde una visión integral e integradora, que considere la diversidad como una oportunidad de aprendizaje y que trascienda la mera transmisión de conocimientos curriculares hacia verdaderos programas integrales que incorporan activamente a los niños/as, adolescentes y sus familias. En este contexto, la presente guía surge en medio de múltiples retos a los que se enfrentan las escuelas ubicadas en territorios rurales, de frontera o de afectación por problemáticas sociales y ambientales.

Effect of mycorrhizae and pH change at the root-soil interface on phosphorus uptake by Sorghum using a rhizocylinder technique

Sorghum (Sorghum bicolor) was grown for 40 days in. rhizocylinder (a growth container which permitted access to rh zosphere and nonrhizosphere soil), in two soils of low P status. Soils were fertilized with different rates of ammonium and nitrate and supplemented with 40 mg phosphorus (P) kg(-1) and inoculated with either Glomus mosseae (Nicol. and Gerd.) or nonmycorrhizal root inoculum.. N-serve (2 mg kg(-1)) was added to prevent nitrification. At harvest, soil from around the roots was collected at distances of 0-5, 5-10, and 10-20 mm from the root core which was 35 mm diameter. Sorghum plants, with and without mycorrhiza, grew larger with NH4+ than with NO3- application. After measuring soil pH, 4 3 suspensions of the same sample were titrated against 0.01 M HCl or 0.01 M NaOH until soil pH reached the nonplanted pH level. The acid or base requirement for each sample was calculated as mmol H+ or OFF kg(-1) soil. The magnitude of liberated acid or base depended on the form and rate of nitrogen and soil type. When the plant root was either uninfected or infected with mycorrhiza., soil pH changes extended up to 5 mm from the root core surface. In both soils, ammonium as an N source resulted in lower soil pH than nitrate. Mycorrhizal (VAM) inoculation did not enhance this difference. In mycorrhizal inoculated soil, P depletion extended tip to 20 mm from the root surface. In non-VAM inoculated soil P depletion extended up to 10 mm from the root surface and remained unchanged at greater distances. In the mycorrhizal inoculated soils, the contribution of the 0-5 mm soil zone to P uptake was greater than the core soil, which reflects the hyphal contribution to P supply. Nitrogen (N) applications that caused acidification increased P uptake because of increased demand; there is no direct evidence that the increased uptake was due to acidity increasing the solubility of P although this may have been a minor effect.