Fluxo de potência ótimo reativo via método da função lagrangiana barreira modificada

Este artigo apresenta uma nova abordagem para a resolução do problema de Fluxo de Potência Ótimo Reativo. Nesta abordagem, as restrições de desigualdade são tratadas pela associação dos métodos de Barreira Modificada e Primal-Dual Barreira Logarítmica (PDBL). As restrições de desigualdade são transformadas em igualdades introduzindo variáveis de folga positivas e são relaxadas através do parâmetro de barreira. Uma função Lagrangiana é associada ao problema modificado. As condições necessárias de primeira ordem são aplicadas à função Lagrangiana, gerando um sistema de equações não-lineares, o qual é linearizado pelo método de Newton. A relaxação das variáveis de folga resulta na expansão da região factível do problema original, permitindo que os limites das restrições de desigualdade sejam atingidos. Testes numéricos utilizando os sistemas CESP-440kV e SUL-SUDESTE BRASILEIRO e um teste comparativo com o método PDBL indicam que a nova abordagem é eficiente na resolução do problema Fluxo de Potência Ótimo Reativo.This work presents a new approach for the resolution of Optimal Reactive Power Flow problem. In this approach, the inequality constraints are treated by the Modified Barrier and Primal-Dual Logarithmic Barrier (PDLB) methods. The inequality constraints are transformed into equalities by introducing positive slack variables and are perturbed by the barrier parameter. A Lagrangian function is associated to the modified problem. The first-order necessary conditions are applied to the Lagrangian function generating a nonlinear system, which is solved by Newton's method. The perturbation of the slack variables results in an expansion of the feasible set of the original problem, allowing the limits of the inequality constraints to be reached. Numeric tests using the CESP and the SOUTH-SOUTHEAST BRAZILIAN systems and a comparative test with PDLB method indicate that the new approach is efficient in the resolution of Optimal Reactive Power Flow problem

Prenormative verification and validation of a protocol for measuring magnetite–maghemite ratios in magnetic nanoparticles

An important step in establishing any new metrological method is a prenormative interlaboratory study, designed to verify and validate the method against its stated aims. Here, the 57Fe Mössbauer spectrometric ‘centre of gravity’ (COG) method was tested as a means of quantifying the magnetite/maghemite (Fe3O4/γ-Fe2O3) composition ratio in biphasic magnetic nanoparticles. The study involved seven laboratories across Europe and North and South America, and six samples—a verification set of three microcrystalline mixtures of known composition, and a validation set of three nanoparticle samples of unknown composition. The spectra were analysed by each participant using in-house fitting packages, and ex post facto by a single operator using an independent package. Repeatability analysis was performed using Mandel’s h statistic and modified Youden plots. It is shown that almost all (83/84) of the Mandel h statistic values fall within the 0.5% significance level, with the one exception being borderline. Youden-based pairwise analysis indicates the dominance of random uncertainties; and in almost all cases the data analysis phase is only a minor contributor to the overall measurement uncertainty. It is concluded that the COG method is a robust and promising candidate for its intended purpose

Prevalence, awareness, treatment, and control of high low-density lipoprotein cholesterol in Brazil : baseline of the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil)

BACKGROUND AND OBJECTIVES: Dyslipidemia is a pivotal risk factor for coronary heart disease (CHD). The purpose of this study was to identify the profile of dyslipidemia in a Brazilian population, according to high low-density lipoprotein (LDL-C) levels. We used the classification of the 2004 update of National Cholesterol Education Program Adult Treatment Panel III (ATP-III). METHODS: Of the 15,105 men and women aged 35 to 74 years enrolled in the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil), we included 14,648 subjects (97%). They had data to categorize them according to the NCEP-ATP-III criteria. We compared 4 categories: ‘‘0–1’’ risk factors, ‘‘2 or more risk factors’’, ‘‘CHD or CHD risk equivalent’’, and ‘‘CHD at very high risk’’. The sociodemographic determinants used were sex, age, ethnicity, income, education, and health insurance. Poisson regression was used to estimate the prevalence ratios for cholesterol (LDL-C), frequency, awareness, treatment, and control of high LDL-C

Synthesis of γ-(Al1-xFex)2O3 solid solutions from oxinate precursors and formation of carbon nanotubes from the solid solutions using methane or ethylene as carbon source

This work reports for the first time the synthesis of ?-(Al1-xFex)2O3 solid solutions with a high specific surface area (200-230 m2/g) by the decomposition of metal oxinate [(Al1-xFex)(C9H6ON)3] and investigated the potential of these materials as catalysts for the synthesis of carbon nanotubes by catalytic chemical vapor deposition using methane or ethylene as carbon the source. The nanocomposite powders prepared by reduction in H2-CH4 contain carbon nanotubes (CNTs), which are mostly double-walled but also contain a fair amount of undesirable carbon nanofibers, hollow carbon particles, and metal particles covered by carbon layers. Moreover, abundant metallic particles are observed to cover the surfaces of the matrix grains. By contrast, the nanocomposite powders prepared by reduction in N2-C2H4 are not fully reduced, and the CNTs are much more abundant and homogeneous. However, they are multiwalled CNTs with a significant proportion of defects. The powders were studied by several techniques including Mössbauer spectroscopy and electron microscopy

Citocalasinas produzidas por Xylaria sp., um fungo endofítico de Piper aduncum (piperaceae)

A chemical study on the EtOAc extract produced by Xylaria sp., an endophytic fungus from Piper aduncum, resulted in the isolation of a new cytochalasin 1, along with five known 19,20-epoxycytochalasin D (2), C (3), N (4), Q (5), and R (6). The 1-6 were evaluated against the fungi C. cladosporioides and C. sphaerospermum and only 5 showed weak activity. The cytotoxicity in vitro against HeLA and CHO cells lines were investigated and the cytochalasins 2-4, and 6 showed a strong activity against HeLA. The DNAdamaging activity of 1-6 were also investigated against mutant strains of S. cerevisiae

Cytochalasins produced by xylaria sp., an endophytic fungus from piper aduncum

A chemical study on the EtOAc extract produced by Xylaria sp., an endophytic fungus from Piper aduncum, resulted in the isolation of a new cytochalasin 1, along with five known 19,20-epoxycytochalasin D (2), C (3), N (4), Q (5), and R (6). The 1-6 were evaluated against the fungi C. cladosporioides and C. sphaerospermum and only 5 showed weak activity. The cytotoxicity in vitro against HeLA and CHO cells lines were investigated and the cytochalasins 2-4, and 6 showed a strong activity against HeLA. The DNAdamaging activity of 1-6 were also investigated against mutant strains of S. cerevisiae331020382041CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPSem informaçãoSem informaçãoSem informaçã

Cytochalasins produced by Xylaria sp., an endophytic fungus from Piper aduncum

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)A chemical study on the EtOAc extract produced by Xylaria sp., an endophytic fungus from Piper aduncum, resulted in the isolation of a new cytochalasin 1, along with five known 19,20-epoxycytochalasin D (2), C (3), N (4), Q (5), and R (6). The 1-6 were evaluated against the fungi C. cladosporioides and C. sphaerospermum and only 5 showed weak activity. The cytotoxicity in vitro against HeLA and CHO cells lines were investigated and the cytochalasins 2-4, and 6 showed a strong activity against HeLA. The DNAdamaging activity of 1-6 were also investigated against mutant strains of S. cerevisiae.331020382041Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)FAPESP_BrasilCNPq_BrasilCAPES_Brasi