Magnetic-field effects in defect-controlled ferromagnetic Ga_{1-x}Mn_xAs semiconductors

We have studied the magnetic-field and concentration dependences of the magnetizations of the hole and Mn subsystems in diluted ferromagnetic semiconductor Ga_{1-x}Mn_xAs. A mean-field approximation to the hole-mediated interaction is used, in which the hole concentration p(x) is parametrized in terms of a fitting (of the hole effective mass and hole/local moment coupling) to experimental data on the Tc critical temperature. The dependence of the magnetizations with x, for a given temperature, presents a sharply peaked structure, with maxima increasing with applied magnetic field, which indicates that application to diluted-magnetic-semiconductor devices would require quality-control of the Mn-doping composition. We also compare various experimental data for Tc(x) and p(x) on different Ga_{1-x}Mn_xAs samples and stress the need of further detailed experimental work to assure that the experimental measurements are reproducible.Comment: RevTeX 4, 3 two-column pages, 4 colour figures; to appear in J Appl Phy

Influence of lanthanum doping on the structure and transport properties of CeO2

LaxCe1-xO2-x/2 materials are oxide and/or proton conductors depending on the La-content and they are of interest for numerous electrochemical applications at high temperatures, including membranes for hydrogen separation and fuel cell electrolytes. Samples with low La-content exhibit (x0.4) crystallize with cubic fluorite type structure; while for x>0.4 the structure is still unclear. The crystal structure of these materials is still unknown, some authors reported that the materials exhibit fluorite type structure in the whole compositional range. However, another authors reported a pyrochlore type structure for x0.5. The stabilization of the fluorite or pyrochlore type structure depends mainly on the oxygen sublattice and the vacancy ordering1. In this contribution, LaxCe1-xO2-δ (0<x0.7) materials are prepared by the freeze-drying precursor method and the sintering conditions have been optimized to obtain dense ceramic samples. A complete structural characterization has been carried out by X-ray powder diffraction and scanning electron microscopy. The average structure determined by conventional XRD indicates that the materials are single fluorite compounds for x0.6. However, the local structure determined by combined electron diffraction and HRTEM is more complex. The SAED patterns reveal diffuse scatterings for x0.5 that have been associated with O-vacancy ordering, leading to a superstructure relative to a single fluorite . This finding is further confirmed by the HRTEM images in the same zone axis. Thermogravimetric and Raman analysis confirmed an increase of oxygen vacancy concentration with La-doping. The overall conductivity was determined by complex impedance spectroscopy in different atmospheres. The samples with high La-content exhibit an important proton contribution at low temperature. In addition, all samples are mixed ion-electronic conductors in hydrogen containing atmosphereUniversidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Failure Evaluation of Reinforced Concrete Beams Using Damage Mechanics and Classical Laminate Theory

The prediction of the behavior of reinforced concrete beams under bending is essential for the perfect design of these elements. Usually, the classical models do not incorporate the physical nonlinear behavior of concrete under tension and compression, which can underestimate the deformations in the structural element under short and long-term loads. In the present work, a variational formulation based on the Finite Element Method is presented to predict the flexural behavior of reinforced concrete beams. The physical nonlinearity due cracking of concrete is considered by utilization of damage concept in the definition of constitutive models, and the lamination theory it is used in discretization of section cross of beams. In the layered approach, the reinforced concrete element is formulated as a laminated composite that consists of thin layers, of concrete or steel that has been modeled as elasticperfectly plastic material. The comparison of numerical load-displacement results with experimental results found in the literature demonstrates a good approximation of the model and validates the application of the damage model in the Classical Laminate Theory to predict mechanical failure of reinforced concrete beam. The results obtained by the numerical model indicated a variation in the stress–strain behavior of each beam, while for under-reinforced beams, the compressive stresses did not reach the peak stress but the stress–strain behavior was observed in the nonlinear regime at failure, for the other beams, the concrete had reached its ultimate strain, and the beam’s neutral axis was close to the centroid of the cross-section

Influence of preparation procedures on the phenolic content, antioxidant and antidiabetic activities of green and black teas

The influence of common tea preparation procedures (temperature, infusion time, consumption time interval and tea bag/loose-leaf) and the type of water used, on the total phenolic content (TPC), the radical scavenging activity and the alpha-glucosidase inhibitory activity were assessed. Higher TPC and antioxidant activity were obtained when using lower mineralized waters. Tea bags also evidenced higher antioxidant activity than loose-leaf samples. Under the same conditions (90 degrees C and five minutes of infusion time) green tea contains almost twice the quantity of polyphenols and the free radical scavenging ability of black tea. In the alpha-glucosidase assay all infusions were active (97-100 %). Furthermore, HPLC allowed to identify some of the polyphenols present in both teas and to monitor their composition change with time. After twenty-four hours, the antioxidant activity was maintained without significant changes, but a small decrease in enzyme inhibition was observed, although this activity was still very high.info:eu-repo/semantics/publishedVersio

Tentativa de controle de Hymenolepis nana através de tratamentos clínicos repetidos, com praziquantel, em uma comunidade fechada

Praziquantel was used repeatedly in an orphanage to determine its effectiveness in controlling hymenolepis. At the same time, the possible mechanisms of the transmission of this parasitosis were studied. The first group examined consisted of 161 people of which 109 were the orphanage children, who varied in age from days or months to eight years, and 52 adults, employees of the institution. Stool tests of all were made about every two months, using the Hoffman, Pons and Janer method; cure control was carried out by the same method seven to fourteen days after treatment. Every two weeks, H. nana eggs were searched for under the finger nails of the children, in insects, in domestic wastes, on door knobs and refrigerator handles, and on toilet flush knobs and strings. Water collected from rinsed urinals and shower floors was also tested. Eggs and larva of helminths and protozoa cysts were found in domestic waste and cockroaches and on door knobs. H. nana eggs were found in puddles of water left on shower floors and the rinse water of urinals. Every patient whose feces had H. nana eggs was treated with a single oral 25mg/kg dose of praziquantel, taken after lunch. In the four groups treated (66 patients in all), no important side effects were observed, and follow-up indicated 100% cure. For the 5th and last treatment, a group of both positive and negative (for H. nana) people was divided into sub-groups and treated with one (25mg/kg) or two doses of the medicine for a period of four days (total: 50mg/kg). Follow-up examination two months after treatment showed that only six patients were still eliminating eggs of the parasite; all belonged to the sub-group treated with a single dose of the drug. In spite of the treatments given an of the high percentage of cure, control of hymenolepiasis was not achieved.Foi feita tentativa de controle do Hymenolepis nana em uma comunidade fechada utilizando-se o praziquantel em repetidos tratamentos. Concomitantemente, foram estudados os prováveis mecanismos de transmissão da parasitose. A comunidade trabalhada possuia inicialmente 161 pessoas, sendo 109 crianças internas, com idade variando de dias e/ou meses a 8 anos, e de 52 adultos, funcionários da instituição. O diagnóstico parasitológico foi realizado aproximadamente de 2 em 2 meses em toda a população, pelo método de Hoffman, Pons e Janer, e o controle de cura, pelo mesmo método, entre o 7.º e o 14.º dia. Quinzenalmente foram realizadas pesquisas para ovos de H. nana no leito ungueal das crianças, em insetos, no lixo doméstico, nas maçanetas das portas e geladeiras, nos botões e cordões de descarga. Posteriormente examinou-se água recolhida dos urinóis e do chão do "box" do chuveiro. Todos os pacientes eliminando ovos de H. nana nas fezes foram tratados com praziquantel, após exame clínico, na dose única oral de 25mg/kg, após o almoço. Em 4 tratamentos realizados (66 pacientes), não foram observadas reações colterais importantes, e o controle de cura foi sempre de 100%. No 5.º e último tratamento, grupos de pacientes positivos e negativos para H. nana foram divididos em subgrupos e tratados com uma dose da droga (25mg/kg) ou duas doses espaçadas de 4 dias (total: 50mg/kg). No levantamento realizado dois meses após o tratamento, foram encontrados apenas 6 indivíduos eliminando ovos do parasita. Estes pertenciam ao subgrupo de crianças com himenolepíase tratado com uma única dose da droga. Ovos e larvas de helmintos e cistos de protozoários foram encontrados no lixo doméstico, insetos (baratas) e maçanetas de portas, enquanto ovos de H. nana só foram achados em água aspirada do "box" do chuveiro e da lavagem dos urinóis. Apesar da elevada percentagem de cura e dos vários tratamentos realizados, não se conseguiu o controle da himenolepíase

Beyond good intentions: the role of the building passport for the sustainable conservation of built heritage to behavioural change

Despite the recognised importance of built heritage for sustainable development, and the multiple tools, recommendations, guidelines, and policies developed in recent years to support decision-making, good sustainable conservation practices often fail to be implemented. Challenges faced by practitioners often relate to external factors, and there is a gap in the understanding of the role of the nature of the designer and the behavioural dimension of the challenges in implementation. This research applies the Theory of Planned Behaviour (TPB) to verify how a building passport for sustainable conservation (BPSC) impacts design students’ intentions and actual design decisions towards built heritage conservation. This research aims to ascertain the role of the BPSC to affect attitudes, subjective norms, and intentions and ultimately change conservation behaviours. The results show that this tool has a positive contribution to reinforce existing attitudinal beliefs. Still, no significant changes were found in the overall conservation behaviours, suggesting that beliefs hindering implementation may more often be related to aesthetic reasons, creativity and innovation, and program requirements, than with beliefs regarding the sustainable performance of the building. This study demonstrates that using the TPB to analyse design processes in the context of built heritage is an innovative methodological approach that contributes to a deeper understanding of the psychological factors affecting sustainability and built heritage conservation decisions.This research was funded by Foundation for Science and Technology (FCT), grant number PD/BD/127853/2016. The APC was funded by TU Delft Library

Sitematización de la asistencia de enfermería al paciente con síndrome de la abstinencia alcohólica en la unidad de emergencia

Este trabalho trata de uma pesquisa bibliográfica cujo objetivo foi identificar o corpo de conhecimentos essenciais para prestar assistência de enfermagem a pacientes portadores da Síndrome da Abstinência Alcoólica na unidade de Pronto Socorro. A fonte principal de dados foi a Base de Dados LILACS, usando-se expressões de pesquisa pertinentes ao tema. Para compor um corpo de conhecimentos essenciais na assistência, os resultados identificaram a necessidade de usar escalas de avaliação da síndrome, ter conhecimentos sobre as manifestações clínicas, saber as terapêuticas existentes e as respectivas intervenções. Concluiu- se que a identificação deste corpo de conhecimentos pode contribuir para dispensar-se uma assistência de enfermagem efetiva a pacientes portadores desta síndrome.This paper is a literature review that aimed to identify a body of essential nursing knowledge to assess patients withAlcoholicWithdrawal Syndrome in Emergency Units. Primary data source was LILACS database using pertinent descriptors. To compose the body of essential knowledge for nursing care, results identified a need to use assessment scales, to have knowledge about clinical manifestations, to know existing therapeutics, and its related interventions. It was concluded that the identification of this body of knowledge can contribute for an effective nursing care to patients with that syndrome.Este artículo es una investigación bibliográfica que tuvo como objetivo identificar un cuerpo esencial de conocimientos de enfermería para el cuidado de pacientes con la Síndrome de la Abstinencia Alcohólica en una unidad de emergencia. Los datos primarios fueran encontrados en la Base de Datos LILACS con el uso de descriptores pertinentes. Para la composición del cuerpo de conocimientos para la asistencia de enfermería, los resultados identificaron la necesidad del uso de escalas de evaluación, tener conocimiento acerca e las manifestaciones clínicas, conocer las terapéuticas existentes y sus respectivas intervenciones. Se concluyó que la identificación de ese cuerpo de conocimientos puede contribuir para una asistencia de enfermería efectiva a pacientes con ese síndrome