Caracterização de correntes de inrush em transformadores monofásicos e desenvolvimento de um circuito para mitigação

Este projeto de diplomação tem como propósito o estudo e entendimento do comportamento das correntes transitórias de magnetização (inrush), especificamente do núcleo de um transformador monofásico, e posterior desenvolvimento de um dispositivo eletrônico que implemente um processo de acionamento proporcionando uma mitigação desta corrente de inrush. O circuito tem seu funcionamento baseado no controle do campo magnético residual do núcleo do transformador através da aplicação de uma corrente CC no enrolamento primário e posterior comando do ângulo de acionamento da fonte alternada da rede de alimentação. O dispositivo desenvolvido pode ter aplicação em manobras de energização de transformadores de subestações se tiver seu projeto adequado. Nesta etapa, o desenvolvimento tem foco didático, pois permite visualizar e controlar o fenômeno da corrente de inrush, permitindo produzir desde a pior como a melhor condição de energização.The purpose of this project is to study and understand the behavior of transient magnetizing currents (inrush) specifically of the core of a single-phase transformer and subsequent development of an electronic device that implements a drive process providing an attenuation of this inrush current. The circuit has its operation based on the control of the residual magnetic field of the transformer core by the application of a DC current in the primary winding and subsequent command of the drive angle of the alternating source of the mains. The developed device may have application in energizing maneuvers of substation transformers if it has its proper design. In this stage, the development has didactic focus, since it allows visualizing and controlling the phenomenon of the inrush current, allowing to produce from the worst as the best condition of energization

Photonic Crystal Fibers infiltrated with Ferroelectric Liquid Crystals

In the letter we present preliminary results of research on thermal and electrical tunability of photonic crystal fibers (PCF) infiltrated with ferroelectric liquid crystal (FLC) molecules. From this combination we expect new spectral properties to be observed, mainly due to the fast switching time of FLC molecules that can lead to the design of a new kind of optical filters. We have also obtained promising results about the spectral properties of photonic ferroelectric liquid crystal fibers (PFLCF), as well as orientation of FLC molecules inside PCF microholes

Influence of Angular Orientation of the Embedded Highly Birefringent Fiber on Pmd Changes Under Axial Stress

In the paper we present results of the research on polarization mode dispersion changes inside the polarimetric optical fiber sensors based on highly birefringent optical fibers embedded into composite materials with different angular orientations of the optical axes. Based on measurements made for different types of highly birefringent optical fiber sensors we have shown that strain sensitivities after lamination process are different in comparison to the data obtained before lamination. Our results indicate that polarization mode dispersion in side-hole highly birefringent fibers under axial stress strongly depends on fiber orientation in the composite material suggesting that orientation of the polarization axes of the highly birefringent fiber can be responsible for behavior of the fiber inside the composite material

Bovine leukemia viral DNA found on human breast tissue is genetically related to the cattle virus

Bovine leukemia virus (BLV) infection is widespread in cattle and associated with B cell lymphoma. In a previousstudy we demonstrated that bovine leukemia viral DNA was detected in human breast tissues and significantly associated with breast cancer. Our current study aimed to determine whether BLV DNA found in humans and cattle at the same geographical region were genetically related. DNA was extracted from the breast tissue of healthy (n = 32) or cancerous women patients (n = 27) and from the blood (n = 30) of cattle naturally infected with BLV, followed by PCR-amplification and partial nucleotide sequencing of the BLV env gene. We found that the nucleotide sequence identity between BLV env gene fragments obtained from human breast tissue and cattle blood ranged from 97.8 to 99.7% and grouped into genotype 1. Thus, our results further support the hypothesis that this virus might cause a zoonotic infection

Identification of enteric viruses circulating in a dog population with low vaccine coverage

Although the use of vaccines has controlled enteric diseases in dogs in many developedcountries, vaccine coverage is still under optimal situation in Brazil. There is a large popula-tion of nonimmunized dogs and few studies about the identification of the viruses associated with diarrhea. To address this situation, stool samples from 325 dogs were analyzed bypolymerase chain reaction for the detection of common enteric viruses such as Canine ade-novirus (CAdV), Canine coronavirus (CCoV), Canine distemper virus (CDV), Canine rotavirus (CRV)and Carnivorous protoparvovirus 1 (canine parvovirus 2; CPV-2). At least one of these specieswas detected in 56.6% (184/325) of the samples. The viruses detected most frequently ineither diarrheic or nondiarrheic dog feces were CPV-2 (54.3% of the positive samples), CDV(45.1%) and CCoV (30.4%), followed by CRV (8.2%) and CAdV (4.9%). Only one agent wasdetected in the majority of the positive samples (63%), but co-infections were present in 37%of the positive samples and mainly included CDV and CPV-2. The data presented herein canimprove the clinical knowledge in regions with low vaccine coverage and highlight the needto improve the methods used to control these infectious diseases in domestic dogs

Photonic crystal fibers infiltrated with metallic nanoparticles dispersed in polydimethylsiloxane

An experimental results on birefringent photonic crystal fiber (PCF) selectively infiltrated with metallic nanoparticles (NPs) dispersed in polydimethylsiloxane (PDMS) are presented. In general, PCFs are structures consisting of periodic matrix of microholes surrounding core region, that can be either solid or hollow

Brain zinc chelation by diethyldithiocarbamate increased the behavioral and mitochondrial damages in zebrafish subjected to hypoxia

The increase in brain levels of chelatable zinc (Zn) in dysfunctions involving oxygen deprivation has stimulated the treatment with Zn chelators, such as diethyldithiocarbamate (DEDTC). However, DEDTC is a redox-active compound and it should be better evaluated during hypoxia. We use the hypoxia model in zebrafish to evaluate DEDTC effects. The exploratory behavior, chelatable Zn content, activities of mitochondrial dehydrogenases, reactive species levels (nitric oxide, superoxide anion, hydroxyl radical scavenger capacity) and cellular antioxidants (sulfhydryl, superoxide dismutase) of zebrafish brain were assessed after recovery, with or without 0.2mM DEDTC. The increased brain levels of chelatable Zn induced by hypoxia were mitigated by DEDTC. However, the novel tank task indicated that DEDTC did further enhance the exploratory deficit caused by hypoxia. Furthermore, these behavioral impairments caused by DEDTC were more associated with a negative action on mitochondrial activity and brain oxidative balance. Thus, due to apparent pro-oxidant action of DEDTC, our data do not support its use for neuroprotection in neuropathologies involving oxygen deprivation

Caracterização do perfil de crises epiléticas e dos efeitos comportamentais induzidos por pilocarpina em peixe-zebra adulto

Epilepsia é um grupo de desordens neurológicas caracterizada por crises epilépticas recorrentes não provocadas, afligindo 50 milhões de pessoas no mundo. Embora grande parte dos casos possa ser controlada através de medicação um número significativo de pacientes torna-se refratários apesar do tratamento com drogas anticonvulsivantes. Apesar do desenvolvimento bemsucedido de várias novas drogas antiepilépticas, a busca por novas terapias com maior eficácia e tolerabilidade ainda permanece um objetivo importante. O modelo de epilepsia induzido por pilocarpina tem sido amplamente utilizado em roedores para o estudo da patogênese da epilepsia do lobo temporal. Embora estes estudos com modelos animais tenham aumentado nossa compreensão das bases patológicas da epilepsia, os complexos mecanismos epileptogênicas e a geração de crises epilépticas ainda não foram completamente elucidados. Ultimamente, foram desenvolvidos estudos avaliando as características comportamentais de peixe-zebra e peixe-zebra (Danio rerio). Esse vertebrado é um modelo experimental que vem se consolidando em áreas da ciência por ter características bastante atrativas como pequeno custo e espaço requerido para manutenção, homologia genética e anatômica tornando-se de grande valia para uma maior compreensão dos mecanismos envolvidos nas crises epilépticas. A partir disso, o objetivo deste trabalho foi avaliar e caracterizar comportalmentalmente as crises epilépticas induzidas por pilocarpina em peixezebra adulto. Para isso, os animais foram pré-tratados com uma curva de concentrações de pilocarpina nas doses de 150, 200, 300, 350 e 400 mg/Kg e filmados por 30 minutos. Com a maior dose foi observado um perfil claro de crise tônico-clônica. O uso do anticonvulsivo escopolamina na dose de 1mg/Kg, ip, 30 minutos antes da aplicação de PILO na maior concentração 400mg/Kg mostrou-se capaz de prevenir a crise tônico-clônica induzida pela PILO. A avaliação comportamental pós-crise foi realizada no aparato open-tank três dias após a crise quando os animais foram filmados por 6 minutos. Foram analisados distância percorrida, tempo móvel, tempo no topo e tempo no fundo. Os resultados deste estudo permitiram uma caracterização temporal das manifestações comportamentais das crises epliepticas em peixe-zebra adulto induzidas por diferentes concentrações de pilocarpina.Epilepsy is a group of neurological disorders characterized by recurrent seizures. It affect about 50 million people worldwide, therefore a public health problem of great importance. While most cases can be controlled through medication, a significant number of patients continue to have seizures despite treatment with anticonvulsant drugs. Despite the successful development of several new antiepileptic drugs, the search for new and more effective therapies and greater tolerability remains an important goal. The pilocarpine model has been extensively used in rodents for the study of neural molecular cascades and mechanisms involved in the pathogenesis of temporal lobe epilepsy. Although studies with animal models have increased our understanding of the pathological bases of epilepsy, the epileptogenic complex mechanisms and the generation of epileptic seizures have not yet been fully elucidated. Lately, studies evaluating behavioral characteristics of zebrafish (Danio rerio) were developed. This vertebrate is an experimental model that has been consolidated in various areas of science for having very attractive features as small cost and space requirements for maintenance, rapid development and life cycle, large offspring, translucent embryos and susceptibility to manipulation and microinjection. Hence, the use of new models becomes of huge value to a greater understanding of the mechanisms involved in this pathology and thus the zebrafish emerges as a complementary alternative for the study of seizures and epilepsy. This study aimed to evaluate and characterize the seizures induced by pilocarpine in adult zebrafish. First, animals were treated with a pilocarpine at different concentrations (150, 200, 300 and 400 mg/kg) and filmed for 30 minutes. Tonic-clonic seizures were observed in the higher dose. When scopolamine, an anticholinergic anticonvulsant, was injected 30 minutes before the higher dose treatment, the pilocarpine-induced seizure was prevented. The post seizure behavioral evaluation was performed in the opentank apparatus three days after injection and filmed for 6 minutes. Measures analyzed in open-tank were distance traveled, moving time and time at the top and in the background. Taken together, our results allowed a temporal characterization of the seizures behavioral manifestations induced by different concentrations of pilocarpine in adult zebrafish

Efeitos promovidos pelo etanol sobre parâmetros do comportamento de grupo em peixe-zebra adulto

A utilização do peixe-zebra como modelo em pesquisas farmacológicas e comportamentais vem crescendo consideravelmente. Isto se deve ao fato da espécie possuir muitas vantagens quando comparada a outros modelos vertebrados. O repertório comportamental descrito é relativamente complexo permitindo a análise de uma série de parâmetros tanto individuais quanto sociais. O comportamento social em peixe-zebra reflete uma interação complexa entre número de animais que se movem juntos de maneira coordenada em um determinado ambiente. O etanol está entre uma das substâncias psicoativas mais ingeridas, exercendo diversos efeitos no sistema nervoso central (SNC). Apesar do número crescente de trabalhos investigando os mecanismos moleculares envolvidos nos efeitos do álcool sobre o SNC, poucos trabalhos avaliam os efeitos da exposição ao etanol sobre o comportamento social do peixe-zebra. Portanto, o objetivo deste trabalho foi avaliar os efeitos promovidos pela exposição aguda ao etanol sobre parâmetros do comportamento de grupo em peixe-zebra adulto. Foram utilizados peixes-zebra adultos expostos a concentrações de 0,5% de etanol durante uma hora. As análises comportamentais foram realizadas em um tanque circular e os parâmetros avaliados foram freqüência das distâncias entre indivíduos, distância média entre indivíduos, área média e distância média dos animais em relação ao centro do aparato ao longo do tempo. Os animais tratados apresentaram maior porcentagem de freqüência em intervalos de maiores distâncias, bem como um aumento das distâncias médias entre indivíduos e quando comparados ao grupo controle. Além disso, os animais expostos ao etanol apresentaram uma maior área formada pelo grupo ao longo do tempo quando comparados ao grupo controle. Não houve alteração significativa nas distâncias em relação ao centro do aparato em ambos os grupos testados. Estes resultados nos indicam que as modificações comportamentais ocasionadas pelo etanol sobre o peixe-zebra levam a uma menor coesão do cardume