Structural and optical properties of Zn0.9 Mn0.1 O/ZnO core-shell nanowires designed by pulsed laser deposition

Partilhar documento na coleção da comunidade Laboratório Associado I3NCore-shell ZnO/ZnMnO nanowires on a-Al2O3 and GaN (buffer layer)/Si (111) substrates were fabricated by pulsed laser deposition using a Au catalyst. Two ZnO targets with a Mn content of 10% were sintered at 1150 and 550 °C in order to achieve the domination in them of paramagnetic MnO2 and ferromagnetic Mn2O3 phases, respectively. Cluster mechanism of laser ablation as a source of possible incorporation of secondary phases to the wire shell is discussed. Raman spectroscopy under excitation by an Ar+ laser revealed a broad peak related to the Mn-induced disorder and a redshift in the A1-LO phonon. Resonant Raman measurements revealed an increase in the multiphonon scattering caused by disorder in ZnO upon doping by Mn. Besides the UV emission, a vibronic green emission band assisted by a ∼ 71 meV LO phonon is also observed in the photoluminescence spectra. Core-shell structures with smooth shells show a high exciton to green band intensity ratio ( ∼ 10) even at room temperature. © 2009 American Institute of PhysicsSANDiE Network of Excellence of the EUFCT-PTDC/FIS/72843/200

In Situ Synchrotron Radiation Small-angle X-ray Scattering Study Of The Kinetics Of Growth Of Cdte Nanocrystals In Borosilicate Glass

A number of isolator-semiconductor nanocrystal composites exhibit quantum confinement effects and nonlinear optical properties. In this work, the formation and growth of CdTe and CdTe0.9S0.1 nanocrystals immersed in a borosilicate glass host matrix were studied by small-angle x-ray scattering using synchrotron radiation during in situ annealing in the 560-580°C temperature range. The values of the average radii of the CdTe nanocrystals determined by using Guinier plots for different annealing times (20-30 Å) agree with those obtained from optical absorption spectroscopy measurements. The nanocrystal size distribution depends on the thermal history and composition of the samples. The existence of other structural heterogeneities having an average size of several hundred ångstroms was detected. © 1995 American Institute of Physics.6621338134

Influence of the concentrations of xanthan gum, hydroxypropyl starch and potassium chloride on the flow properties of drilling fluid formulations

Drilling operation of oil wells involves high costs and risks. With recent discoveries of deeper reservoirs and difficult to access, there was an increase in the number of horizontal wells drilled and far-reaching, and, thereat, new challenges with operational problems. Fluids, or muds, drilling are essential to the well drilling process, confirming the need to study and find physical, rheological, and filtration properties, appropriate to the complexities in each section and the drilling stage. Optimized formulation is the one that comprises a safe operation, mitigation of operational problems, environmental protection, low cost, and high productivity. Thus, this paper offers the study of the rheological properties, and determination of filtrate volume, of the aqueous base fluid formulations, developed with polymeric additives. A high performance formulation, presenting technical-economical feasibility for drilling operations, was achieved using 0.43% m/v of viscosifier (xanthan gun), 0.57% m/v of filtrate controller (hydroxypropyl starch) and 4.57% m/v of clay swelling inhibitor (KCl).La operación de perforación de pozos de petróleo implica altos costos y riesgos. Con los recientes descubrimientos de depósitos más profundos y de difícil acceso, hubo un aumento en el número de pozos horizontales perforados y de largo alcance y, por lo tanto, nuevos desafíos con problemas operacionales. Los fluidos o los lodos de perforación son esenciales para el proceso de perforación del pozo, confirmando la necesidad de estudiar y encontrar propiedades físicas, reológicas y de filtración, adecuadas a las complejidades de cada sección ya la fase de perforación. La formulación optimizada es aquella que comprende una operación segura, mitigación de problemas operacionales, protección ambiental, bajo costo y alta productividad. Así, este trabajo ofrece el estudio de las propiedades reológicas y de volumen de filtrado de las formulaciones de fluidos de base acuosa, desarrolladas con aditivos poliméricos. Una formulación de alto rendimiento, presentando viabilidad técnico-económica para operaciones de perforación, fue alcanzada utilizando 0,43% mv de viscosificante (goma xantana), 0,57% m / v de controlador de filtrado (hidroxipropilamido) y 4,57% m / v de inhibidor de la hinchazón de arcilla (KCl)

Tin determination in fistula seals from Conimbriga and Augusta Emerita

info:eu-repo/semantics/publishedVersio

O AVANÇO DA OCUPAÇÃO ANTRÓPICA EM ÁREA DE RISCO NA SERRA DO TEPEQUÉM - RR

A serra do Tepequém, no Norte do estado de Roraima, tem passado por intensas modificações em sua paisagem ocasionada tanto por ação natural como antrópica. A ocupação na região tem contribuído para retirada da vegetação e abertura de estradas, o que intensifica a vulnerabilidade do solo e os impactos ambientais e antrópicos. Na serra, as construções ocupam áreas próximas a encostas, rede de drenagem e feições erosivas lineares que apresentam dinâmica constante em decorrência da ação climática

EFEITO DA LASERTERAPIA EM TENDINITE EXPERIMENTAL NO TENDÃO FLEXOR DIGITAL SUPERFICIAL EM EQÜINOS: ESTUDO HISTOLÓGICO E ULTRA-SONOGRÁFICO

Foi analisado o efeito da laserterapia com emissão do raio laser arsenieto de gálio na reparação tendínea de eqüinos após indução de tendinite experimental. Foram utilizados 10 eqüinos, SRD, com idade média de 2 a 5 anos, selecionados quanto a normalidade do aparelho locomotor. A tendinite foi induzida pela injeção de colagenase C1639 Tipo I-S na concentração de 2,5 mg/ml na dose de 0,5 ml nos tendões flexores superficiais de ambos os membros anteriores. Após 48 horas da injeção da colagenase, foram realizados exames ultra-sonográficos consecutivos com intervalos de 24 horas, para avaliação das alterações ocorridas no tendão e instituído a laser terapia diária por 15 dias com emissão local do raio laser Arsenieto de Gallium na dose de 8 joules/cm² no membro anterior esquerdo, permanecendo o contra-lateral (direito) como controle. No 40º dia de avaliação ultra-sonográfica realizou-se biópsia na região da lesão para exames histológicos. Os exames ultrasonográfico e histológico não demonstraram diferenças entre os membros tratados e os membros controle. Esses resultados demonstraram que o raio laser Arsenieto de Gallium na dosimetria de 8 joules/cm² não interferiu de forma significativa no processo de reparação tendínea. Effects of laser therapy on experimental tendinitis in horses: ultrasonographic and histologic study Abstract Ultrasonography is being used very successfully for the evaluation of equine soft tissues, improving the diagnosis and monitoring soft tissue musculskeletal injury accurately and noninvasively. The superficial digital flexor tendon is by far the most frequently involved tendon in sport horse injury, being this way, highly adequate for ultrasonographic characterization and healing. Colagenase was injected bilaterally in the superficial digital flexor tendon, at the medium third metacarpus in ten horses. Ultrasonography was performed 24 hours later in order to study the effect if this inflammatory agent on the tendon ultrasongraphy was performed using a real time ultrasound with 7.5 MHz transducer. According to GENOVESE et al. (1986) classification, types II and III injuries were observed. One limb of each horse was treated with soft laser daily for 15 consecutive days using 8 joules/cm. The opposite limb was used as control. Ultrasonography was performed every 48 hours for 40 days showing no difference in the healing between treated and untreated limbs. No significant differences were observed between the histological aspects of the superficial digital flexor tendon healing and the ultrasonographic images. It was possible then to conclude that laser therapy did not interfere in the tendon healing

Yield response of field beans (Vicia faba) to plant population and sowing date in a temperate climate

peer-reviewedSowing date and seed rate influence crop establishment, growth, yield and profitability. The growth and yield of field beans (Vicia faba) in response to sowing date and seed rate was examined over three seasons, 2016–2019, in Teagasc, Oak Park, Carlow, Ireland. Early winter sowings (October) established better than late winter sowings in November and January. No significant difference was found in establishment from mid-February to mid-March. Yield was generally highest from October sowings for the winter cultivar. Yields were similar from February, March and April sowings for the spring cultivar, with March generally yielding higher across the three seasons. Yield was also found to increase significantly with seed rate for both winter and spring cultivars. The economic optimum plant population was estimated for the October and March sowing dates, by fitting a standard (linear + exponential) curve. There is no published information on the optimum plant populations for field beans in Ireland and we believe we are the first to report these findings. The estimated economic optimum plant populations varied between 13 and 38 plants/m2 for both varieties, with an average optimum of 25.5 plants/m2. This range falls within the current recommendations for sowing field beans in Ireland, demonstrating that increasing plant populations above the current commercial practice for field beans in Ireland, will not increase yield or profitability

Incorporating oldman saltbush hay and prickly pear in diets for red Sindhi calves

This study was designed to evaluate the nutrient intake, digestibility, degradability, and ruminal characteristics of Sindhi heifers fed diets that contained a combined total of 75% oldman saltbush hay (hereafter saltbush hay) and prickly pear cactus. Eight 12-month old intact male red Sindhi calves (four fistulated and four non-fistulated) with an initial mean weight of 170 ± 5 kg were assigned to 4 × 4 Latin squares, where factors consisted of four diets, namely 15% hay and 60% cactus; 30% hay and 45% cactus; 45% hay and 30% cactus; and 60% hay and 15% cactus, and four times at which rumen fluid was collected. Neutral detergent fibre (NDF) and acid detergent fibre (ADF) intakes in kg/day and NDF in percentage live weight (LW), water intake, salinity, and conductivity increased with hay level. Intake and digestibility of non-fibrous carbohydrates were curvilinear with higher values in diets containing 30% saltbush hay. The apparent digestibility of dry matter (DM) and organic matter decreased linearly as the concentration of saltbush hay increased in the diet. The pH of the rumen fluid was within the acceptable range for favourable microbial growth. The low temperature and high salinity and conductivity indices in the diets should be viewed with caution at higher concentrations of saltbush hay, because of a possible decrease in nutrient absorption and the development of health problems in the animals. Apparent degradability coefficients of DM and NDF were affected significantly by inclusion of prickly pear and saltbush hay in the diets.Keywords: animal nutrition, apparent digestibility, Atriplex nummularia Lindl, Opuntia ficus, ruminal degradation, semi-arid environmen

Microwave dielectric permittivity and photoluminescence of Eu 2O3 doped laser heated pedestal growth Ta 2O5 fibers

Partilhar documento na coleção da comunidade Laboratório Associado I3NWe report the microwave dielectric properties and photoluminescence of undoped and europium oxide doped Ta2O5 fibers, grown by laser heated pedestal growth technique. The effects of Eu2O3 doping 1–3 mol % on the structural, optical, and dielectric properties were investigated. At a frequency of 5 GHz, the undoped material exhibits a dielectric permittivity of 21 and for Eu2O3 doped Ta2O5 samples it increases, reaching up to 36 for the highest doping concentration. Nevertheless, the dielectric losses maintain a very low value. For this wide band gap oxide, Eu3+ optical activation was achieved and the emission is observed up to room temperature. Thus, the transparency and high permittivity make this material promising for electronic devices and microwave applications. © 2008 American Institute of Physics.FCT-PTDC/FIS/66262/06FCT-PTDC/CTM/66195/200