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1. The IRAK1/IRF5 axis initiates IL-12 response by dendritic cells and control of Toxoplasma gondii infection

Author

Milton Pereira, Theresa Ramalho, Warrison A. Andrade, Danielle F. Durso, Maria C. Souza, Katherine A. Fitzgerald, Douglas T. Golenbock, Neal Silverman, and Ricardo T. Gazzinelli

Subjects
CP: Immunology, CP: Microbiology, Biology (General), QH301-705.5
Abstract

Summary: Activation of endosomal Toll-like receptor (TLR) 7, TLR9, and TLR11/12 is a key event in the resistance against the parasite Toxoplasma gondii. Endosomal TLR engagement leads to expression of interleukin (IL)-12 via the myddosome, a protein complex containing MyD88 and IL-1 receptor-associated kinase (IRAK) 4 in addition to IRAK1 or IRAK2. In murine macrophages, IRAK2 is essential for IL-12 production via endosomal TLRs but, surprisingly, Irak2−/− mice are only slightly susceptible to T. gondii infection, similar to Irak1−/− mice. Here, we report that upon T. gondii infection IL-12 production by different cell populations requires either IRAK1 or IRAK2, with conventional dendritic cells (DCs) requiring IRAK1 and monocyte-derived DCs (MO-DCs) requiring IRAK2. In both populations, we identify interferon regulatory factor 5 as the main transcription factor driving the myddosome-dependent IL-12 production during T. gondii infection. Consistent with a redundant role of DCs and MO-DCs, mutations that affect IL-12 production in both cell populations show high susceptibility to infection in vivo.

Published
2024
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2. Arachidonic acid inhibition of the NLRP3 inflammasome is a mechanism to explain the anti-inflammatory effects of fasting

Author

Milton Pereira, Jonathan Liang, Joy Edwards-Hicks, Allison M. Meadows, Christine Hinz, Sonia Liggi, Matthias Hepprich, Jonathan M. Mudry, Kim Han, Julian L. Griffin, Iain Fraser, Michael N. Sack, Christoph Hess, and Clare E. Bryant

Subjects
CP: Metabolism, CP: Immunology, Biology (General), QH301-705.5
Abstract

Summary: Elevated interleukin (IL)-1β levels, NLRP3 inflammasome activity, and systemic inflammation are hallmarks of chronic metabolic inflammatory syndromes, but the mechanistic basis for this is unclear. Here, we show that levels of plasma IL-1β are lower in fasting compared to fed subjects, while the lipid arachidonic acid (AA) is elevated. Lipid profiling of NLRP3-stimulated mouse macrophages shows enhanced AA production and an NLRP3-dependent eicosanoid signature. Inhibition of cyclooxygenase by nonsteroidal anti-inflammatory drugs decreases eicosanoid, but not AA, production. It also reduces both IL-1β and IL-18 production in response to NLRP3 activation. AA inhibits NLRP3 inflammasome activity in human and mouse macrophages. Mechanistically, AA inhibits phospholipase C activity to reduce JNK1 stimulation and hence NLRP3 activity. These data show that AA is an important physiological regulator of the NLRP3 inflammasome and explains why fasting reduces systemic inflammation and also suggests a mechanism to explain how nonsteroidal anti-inflammatory drugs work.

Published
2024
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3. Regulation of innate immune signaling by IRAK proteins

Author

Milton Pereira and Ricardo T. Gazzinelli

Subjects
TLR, IRAK, innate immunity, cell signaling, IL-1R, inflammation, Immunologic diseases. Allergy, RC581-607
Abstract

The Toll-like receptors (TLRs) and interleukin-1 receptors (IL-1R) families are of paramount importance in coordinating the early immune response to pathogens. Signaling via most TLRs and IL-1Rs is mediated by the protein myeloid differentiation primary-response protein 88 (MyD88). This signaling adaptor forms the scaffold of the myddosome, a molecular platform that employs IL-1R-associated kinase (IRAK) proteins as main players for transducing signals. These kinases are essential in controlling gene transcription by regulating myddosome assembly, stability, activity and disassembly. Additionally, IRAKs play key roles in other biologically relevant responses such as inflammasome formation and immunometabolism. Here, we summarize some of the key aspects of IRAK biology in innate immunity.

Published
2023
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4. El problema de la obediencia moral del derecho desde los presupuestos teóricos y conceptuales de la ética normativa

Author

Yezid Carrillo De la Rosa, Milton Pereira Blanco, and Fernando Luna Salas

Subjects
obediencia moral, derecho, ética normativa, jurisprudencia constitucional, justicia, Philosophy (General), B1-5802
Abstract

El presente artículo de reflexión es el resultado de una investigación que tuvo un enfoque metodológico cualitativo que se expresó en dos dimensiones: uno analítico-conceptual y otro crítico-hermenéutico, y está dirigido primordialmente a examinar el problema de la obediencia moral al derecho desde los presupuestos teóricos y conceptuales de la ética normativa. Sosteniendo como tesis principal que la ética no puede equipararse a una moral aplicada, en la medida que esto implicaría confundir la ética con la moral y por el contrario, el cumplimiento de las normas se da por ser lo moralmente correcto, en consecuencia, será posible concluir a través del presente trabajo que existe una obligación moral de cumplir el derecho, salvo juicios morales concretos frente a ciertas regulaciones de conductas establecidas por normas que no estén acorde a los valores críticos o morales.

Published
2022
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5. Volume total e número de repetições máximas durante séries de treinamento resistido: método tradicional vs série agonista-antagonistado

Author

William Peneda Tozei, Milton Pereira Amaral, Washington Pires, Renato Melo Ferreira, and Everton Rocha Soares

Subjects
Treinamento Resistido, Métodos de Treinamento, Repetições máximas, Sports, GV557-1198.995
Abstract

OBJETIVO: Comparar volume total e número repetições máximas (nRM) que pode ser realizado nos exercícios rosca direta (RD) e tríceps na polia (TP), variando a ordem de execução, nos métodos tradicional (TRAD) e série pareada agonista-antagonista (SPAA). MÉTODOS: Doze indivíduos (22±3,5 anos) com experiência em treinamento resistido (TR), compareceram a 10 sessões com intervalo de 48 a 72 horas entre elas. Após avaliação antropométrica, três sessões de familiarização e realização de testes de uma repetição máxima (1-RM) e reprodutibilidade de 1-RM, foram realizados quatro protocolos experimentais para mensuração do nRM, utilizando 70% de 1-RM: TRAD1 (quatro séries no exercício RD + quatro séries no exercício TP); TRAD2 (quatro séries no exercício TP + quatro séries no exercício RD); SPAA1 (quatro séries no exercício RD e TP) e; SPAA2 (quatro séries no exercício TP e RD). Sob o método TRAD, foram implementados intervalos de 90 segundos entre todas séries realizadas; um intervalo de descanso de dois minutos foi implementado entre a conclusão da última série do primeiro exercício e a primeira série do segundo exercício (RD + TP ou TP + RD). Sob o método SPAA, nenhum intervalo foi implementado entre o primeiro e segundo exercício (RD e TP ou TP e RD); noventa segundos de intervalo de descanso foram implementados após conclusão do primeiro e do exercício subsequente. RESULTADOS: Não foram observadas diferenças no volume total e percepção subjetiva do esforço (PSE) entre os protocolos experimentais, enquanto foi verificado maior nRM no exercício TP em comparação com o RD em todos os protocolos utilizados. CONCLUSÃO: Na intensidade de 70% de 1-RM, o volume total não é influenciado pelo método de TR (TRAD ou SPAA) e pela ordem dos exercícios (RD e TP ou TP e RD). Adicionalmente, observou-se que o nRM parece ser influenciado pelo grupamento muscular utilizado.

Published
2020
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6. CARD9 negatively regulates NLRP3-induced IL-1β production on Salmonella infection of macrophages

Author

Milton Pereira, Panagiotis Tourlomousis, John Wright, Tom P. Monie, and Clare E. Bryant

Subjects
Science
Abstract

IL-1β is important for control of bacterial infections, but when deregulated can lead to excessive inflammation. The authors show that the adaptor protein CARD9 suppresses levels of IL-1β and is downregulated during S. Typhimuriuminfection, thus facilitating an inflammatory response

Published
2016
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7. Principio de proporcionalidad, argumentación jurídica y potestad discrecional de la administración pública: análisis desde los límites a los derechos y garantías fundamentales

Author

Yezid Carrillo-de la Rosa and Milton Pereira-Blanco

Subjects
Argumentación jurídica, Principio de proporcionalidad, Potestad reglada encubierta, Potestad discrecional aparente, Public law, K3150
Abstract

En este trabajo se analiza el problema jurídico referente a qué implicaciones tiene la aplicación del principio de proporcionalidad frente a las decisiones administrativas de las autoridades que limiten o restrinjan libertades y garantías fundamentales. A partir de lo anterior se sostiene, como tesis central, que la facultad discrecional de la administración pública para la expedición de actos administrativos que impliquen restricciones a los derechos y garantías fundamentales de las personas es supuesta e hipotética, teniendo en cuenta que el margen de libertad de la autoridad para escoger las condiciones de tiempo, modo y lugar es inexistente, ya que la autoridad se obliga necesariamente a la adopción del medio necesario para el logro del fin que sacrifique en menor medida los principios constitucionales afectados por el uso de esos medios.

Published
2017
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8. SISTEMA ALTERNATIVO PARA O DESAGUAMENTO EM MACIÇOS ROCHOSOS DE BAIXA PERMEABILIDADE

Author

Ana Carolina Ferreira Xavier, Antônio Carlos Bertachini, Daniel Perez Bertachini, and Milton Pereira Filho

Subjects
River, lake, and water-supply engineering (General), TC401-506, Physical geography, GB3-5030
Abstract

O desaguamento de materiais de baixa condutividade hidráulica é um desafio recorrente para o desenvolvimento de minas abaixo do nível d’água subterrâneo. Nesse contexto, os estudos hidrogeológicos aqui apresentados buscaram fornecer subsídios para a execução de um sistema de drenagem para o talude leste da Mina Várzea do Lopes, no município de Itabirito, MG. Devido sua composição de baixa condutividade hidráulica, esse talude, representado principalmente por MDD, apresenta grande dificuldade de desaguamento, acarretando problemas de estabilidade geotécnica. Com intuito de aprimorar o rebaixamento do nível d’água na mina, foi proposto um projeto alternativo, utilizando-se da elevada condutividade hidráulica do aquífero Cauê para o desaguamento das unidades de baixa condutividade hidráulica. O princípio básico desse sistema foi criar zonas de conexão entre o aquífero Cauê subjacente e o aquitardo MDD, através de drenos no talude os quais alimentariam o Cauê, cujo nível d’água é rebaixado por poços tubulares de alta vazão. Para seu dimensionamento, foi utilizado o software Visual ModFlow, no qual realizou-se simulações numéricas do projeto proposto. Com base nos resultados foi realizada a instalação de baterias de drenos, sendo obtidos resultados satisfatórios para o rebaixamento do aquitardo, deixando o talude leste em melhores condições de drenagem e estabilidade geotécnica.

Published
2017

9. Principio de confianza legítima y acción de lesividad: elementos para una discusión

Author

Milton Pereira Blanco

Subjects
Acción de Lesividad, principio de confianza legítima, nulidad de actos administrativos, buena fe, seguridad jurídica, Law in general. Comparative and uniform law. Jurisprudence, K1-7720
Abstract

En este trabajo se sostiene, como tesis central, que la declaratoria de nulidad de actos administrativos demandados en acción de lesividad no siempre lesiona el principio de confianza legítima. Se precisa, en este sentido, que el único presupuesto para lesionar tal principio, en las condiciones descritas anteriormente, se presenta cuando el acto administrativo tiene apariencia de licitud pero dentro de su contexto normativo encierra una nulidad. Lo anterior, a partir del problema jurídico planteado, así: ¿Existe lesión a la confianza legítima por parte del Estado cuando se declara la nulidad de los actos administrativos mediante la acción de lesividad?

Published
2013

11. Efeito da suplementação dietética de arginina na cicatrização das anastomoses colônicas em ratos Effects of oral arginine supplementation on the healing of colonic anastomoses in rats

Author

Milton Pereira Corrêa-Neto, Antonio Carlos Ligoki Campos, Alessandra Borges Branco, and Jorge Eduardo Fouto Matias

Subjects
Arginina, Cicatrização, Tensiometria, Colágeno, Angiogênese, Arginine, Healing, Tensiometer, Collagen, Angiogenesis, Surgery, RD1-811, Diseases of the digestive system. Gastroenterology, RC799-869
Abstract

RACIONAL: A arginina, aminoácido condicionalmente essencial, participa de diversos processos fisiológicos, em particular na cicatrização e na função imune. OBJETIVO: Avaliar o efeito da suplementação por via oral da arginina na cicatrização colônica em ratos. MÉTODO: Foram utilizados 47 ratos Wistar machos, adultos, com peso médio de 345,45 ± 8,35g, alocados em gaiolas coletivas em grupos cinco ou seis animais. Todos receberam água e ração ad libitum, pesados a cada dois dias e randomizados para receberem por gavagem suplementação com arginina a 10% (grupo ARG) ou solução de aminoácidos a 10% (grupo AA) de forma isovolumétrica, isocalórica e isonitrogenada (1,5 g/kg/dia) por sete dias antes do procedimento operatório e quatro após. Um terceiro grupo recebeu solução salina isotônica (grupo SSI), isovolumetricamente. Os ratos foram submetidos a duas colônicas término-terminais confeccionadas 3 cm distais à válvula ileocecal e outra 5 cm distais à primeira, em plano único com fio monofilamentar de nylon 5-0, e foram sacrificados no 5º dia de pós-operatório Neste dia, as duas anastomoses foram ressecadas, sendo uma conservada em solução salina para medidas de tração e a outra enviada à anatomia patológica, para análise do colágeno (total, maduro e imaturo), e imunoistoquímica para a pesquisa de miofibroblastos e neovascularização. Foi avaliado o peso corpóreo ao longo do experimento. A análise estatística foi realizada com os testes t de Student e de Mann-Whitney. RESULTADOS: A comparação referente ao peso nos três grupos não evidenciou diferença significativa nos pesos iniciais, mas foi observada diferença entre os finais nos grupos SSI e AA (324,7g vs. 298g, P=0,04). A tensão foi significativamente maior no grupo AA quando comparado ao grupo SSI (0,94kgf/cm² vs 0,67 kgf/cm², P=0,04), mas não em relação ao grupo ARG (0,94kgf/cm² vs 0,70 kgf/cm², P=0,09). Quanto à força máxima de tração observou-se diferença significativa entre o grupo AA e o grupo SSI (0,18kgf vs 0,13 kgf, P=0,04) mas não em relação ao grupo ARG (0,18kgf vs 0,14 kgf, P=0,08). A força de ruptura total evidenciou valor significativamente maior para o grupo AA quando comparado ao grupo ARG (0,10kgf vs 0,06 kgf, P=0,05), mas não em relação ao grupo SSI (0,10kgf vs 0,09 kgf, P=0,54). Não foi observada diferença significativa quanto à concentração dos colágenos subtipo I e III e nem do índice de maturação de colágeno nos três grupos. Não foi observada também diferença significativa em relação à contagem de vasos sanguíneos ou miofibroblastos pela imunoistoquímica entre os três grupos. CONCLUSÃO: A administração de solução contendo 20 aminoácidos se mostrou mais efetiva do que a administração isolada de arginina nas provas de tração das anastomoses colônicas.BACKGROUND: Arginine, a conditionally essential amino acid, participates in various physiological processes, particularly in wound healing and immune function. AIM: To evaluate the effect of oral supplementation of arginine on colonic healing in rats. METHODS: Forty-seven male adult Wistar rats, with an average weight of 345.45 ± 8.35 g were used. They were placed in collective cages in groups five or six animals. All received water and food ad libitum, were weighed every two days and randomized to receive supplementation by gavage with a 10% arginine solution (ARG group) or an isovolumetric, isocaloric and isonitrogenous (1, 5 g / kg / day) 10% amino acids solution (group AA) for seven days before the procedure and four after surgery. A third group received isovolumetric isotonic saline solution (group SSI). All rats were subjected to two end to end colonic anastomoses, one 3 cm distal to the ileocecal valve and another 5 cm distal from the first, in a single layer with monofilamentar nylon 5-0, and were sacrificed at 5 days post-surgery. At sacrifice, both anastomoses were resected, one was kept in a saline solution for traction measurements while the other was sent to pathology for analysis of collagen (total, mature and immature) and immunohistochemistry for the detection of myofibroblasts and neovascularization. We evaluated the body weight throughout the experiment. Statistical analysis was performed using the Student t test and Mann-Whitney test. RESULTS: The comparison of body weight in the three groups showed no significant difference in initial weights, but a difference was observed between the groups SSI and AA in final weight (324.7 g vs. 298g, P = 0.04). The tension strength was significantly higher in the AA group as compared to SSI (0.94 kgf / cm ² vs. 0.67 kgf / cm ², P = 0.04) but not when compared to the ARG group (0.94 kgf / cm ² vs. 0.70 kgf / cm ², P = 0.09). For the maximal tension strength there was a significant difference between the AA group and the SSI group (0.18 vs 0.13 kgf kgf, P = 0.04) but not when compared to the ARG group (0.18 vs 0.14 kgf kgf , P = 0.08). The total rupture strength of showed significantly higher values for the AA group as compared to the ARG group (0.10 vs 0.06 kgf kgf, P = 0.05) but not when compared to the SSI group (0.10 vs 0.09 kgf kgf, P = 0.54). There was no significant difference in the concentration of collagen subtypes I and III and also no difference in the collagen maturation index in the three groups. There was also no significant difference on the number of blood vessels (angiogenesis) or myofibroblasts by immunohistochemistry among the three groups. CONCLUSIONS: The administration of a solution containing 20 amino acids was more effective than arginine alone on the healing of colonic anastomoses in rats.

Published
2009
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12. Down regulation of NO signaling in Trypanosoma cruzi upon parasite-extracellular matrix interaction: changes in protein modification by nitrosylation and nitration.

Author

Milton Pereira, Chrislaine Soares, Gisele André Baptista Canuto, Marina Franco Maggi Tavares, Walter Colli, and Maria Julia M Alves

Subjects
Arctic medicine. Tropical medicine, RC955-962, Public aspects of medicine, RA1-1270
Abstract

BACKGROUND:Adhesion of the Trypanosoma cruzi trypomastigotes, the causative agent of Chagas' disease in humans, to components of the extracellular matrix (ECM) is an important step in host cell invasion. The signaling events triggered in the parasite upon binding to ECM are less explored and, to our knowledge, there is no data available regarding •NO signaling. METHODOLOGY/PRINCIPAL FINDINGS:Trypomastigotes were incubated with ECM for different periods of time. Nitrated and S-nitrosylated proteins were analyzed by Western blotting using anti-nitrotyrosine and S-nitrosyl cysteine antibodies. At 2 h incubation time, a decrease in NO synthase activity, •NO, citrulline, arginine and cGMP concentrations, as well as the protein modifications levels have been observed in the parasite. The modified proteins were enriched by immunoprecipitation with anti-nitrotyrosine antibodies (nitrated proteins) or by the biotin switch method (S-nitrosylated proteins) and identified by MS/MS. The presence of both modifications was confirmed in proteins of interest by immunoblotting or immunoprecipitation. CONCLUSIONS/SIGNIFICANCE:For the first time it was shown that T. cruzi proteins are amenable to modifications by S-nitrosylation and nitration. When T. cruzi trypomastigotes are incubated with the extracellular matrix there is a general down regulation of these reactions, including a decrease in both NOS activity and cGMP concentration. Notwithstanding, some specific proteins, such as enolase or histones had, at least, their nitration levels increased. This suggests that post-translational modifications of T. cruzi proteins are not only a reflex of NOS activity, implying other mechanisms that circumvent a relatively low synthesis of •NO. In conclusion, the extracellular matrix, a cell surrounding layer of macromolecules that have to be trespassed by the parasite in order to be internalized into host cells, contributes to the modification of •NO signaling in the parasite, probably an essential move for the ensuing invasion step.

Published
2015
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13. Experimental models of 'Basement'-controlled salients - application to the proterozoic fold-thrust belt of the quadrilátero ferrífero (Minas Gerais, Southeastern Brazil)

Author

Caroline J. S. Gomes, Milton Pereira-Filho, and Silvia C. M. Braga

Subjects
modelagem física, saliências, deformação rúptil, deformação dúctil, Quadrilátero Ferrífero, experimental modelling, salients, brittle deformation, ductile deformation, Science
Abstract

Scaled sandbox models are used to simulate the development of ´basement´-controlled, salients. We investigate the controlling factors on the development of closed curvatures in map-view, considering constant both the sand pack thickness and the space between obstacles. These models are compared with the Fundão-Cambotas Fault System in the Proterozoic fold-thrust belt in the Quadrilátero Ferrífero region, along the southeastern margin of the São Francisco craton. In the experiments, a pronounced curvature resulted from the margin-controlled salient process in the presence (i) of a basal ductile detachment, or (ii) of pre-existing structures. The results suggest that the convex-to-the-foreland, west-vergent Fundão-Cambotas Fault System that borders the Archean basement highs and displaced older Transamazonian structures westward, is partly a consequence of interaction of propagating thrusts with obstacles in the foreland.Em presente trabalho são desenvolvidos experimentos, em escala, em caixas de areia, para a simulação de saliências pelo processo de propagação de sistemas compressivos ao longo de margens irregulares. Estes modelos visam analisar a configuração estrutural do Sistema de Cisalhamento Fundão-Cambotas, no cinturão de dobras e falhas proterozóico, do domínio leste do Quadrilátero Ferrífero, sudeste do Craton São Francisco. Investigaram-se as possíveis causas para a formação de curvaturas, em planta, mantendo-se constantes os parâmetros, espessura do pacote de areia e distância entre obstáculos no antepaís. Os experimentos demonstram que a formação de saliências fortemente curvas ocorre ao longo de margens irregulares, na presença de um descolamento basal dúctil ou pela ação de estruturas pré-existentes. Assim, relaciona-se a geometria convexa do Sistema de Cisalhamento Fundão-Cambotas, ladeado, a norte e a sul, por altos estruturais do embasamento arqueano, vergente para oeste e que desloca estruturas transamazônicas, mais antigas, parcialmente à ação de obstáculos laterais.

Published
2003
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14. ESTUDOS SOBRE OS EFEITOS DA RECARGA ARTIFICIAL (RA) SOBRE O AQUÍFERO CAUÊ, NO QUADRILÁTERO FERRÍFERO-MG

Author

MAURÍCIO NICOLAU BERTACHINI, ANTÔNIO CARLOS BERTACHINI, BRENO ALEXANDRE PEREIRA, CÉSAR AUGUSTO PAULINO GRANDCHAMP, FLÁVIO SOARES NUNES, and MILTON PEREIRA FILHO

Subjects
River, lake, and water-supply engineering (General), TC401-506, Physical geography, GB3-5030
Abstract

O presente estudo buscou avaliar o efeito de uma cava fechada como uma estrutura de recarga artificial (RA) em um ambiente de mineração de ferro. Para tanto, foram escolhidas regiões onde existem minerações de ferro e áreas com características hidrogeológicas similares, porém sem atividades de mineração. As regiões selecionadas encontram-se sobre o Aquífero Cauê, no contexto geológico do Quadrilátero Ferrífero. Foram então calculados os valores de escoamento de base a partir do monitoramento das vazões de descarga do Aquífero Cauê. Os números encontrados foram então correlacionados às taxas de recarga conforme metodologia apresentada por CUSTÓDIO & LLAMAS (2001). Os resultados encontrados indicam que em uma região onde houve a formação de uma cava fechada de lavra de ferro, a mesma funcionou como uma excelente estrutura de RA para o Aquífero Cauê, elevando a taxa de recarga e até mesmo dobrando a mesma.

Published
2012

18. Evaluation of FeCrNiMo coating Tribological performance produced through laser directed energy deposition sliding under biodegradable oils

Author

Éddie Magnus Da Luz, Richard de Medeiros Castro, Milton Pereira, Rafael Gomes Nunes Silva, and Adriano de Souza Pinto Pereira

Abstract

Improving the performance of mechanical components and reducing machine energy consumption involves the correct selection of lubricants and their contact surfaces. The use of biodegradable hydraulic fluids along with less environmental impact surfaces is one example. In this sense, the following paper aims to analyze the behavior of mineral oil (HLP) and biodegradable oils (HEPR and HETG) submitted to a sliding with pins manufactured in PTFE and Al2O3 against a flat substrate coated with FeCrNiMo by the Laser Directed Energy Deposition (L-DED) process. Coatings by this replacement deposition process are proving to be a promising alternative in the replacement of hard chromium, a harmful material to human health. The slip tests were performed in a pin-on-disk tribometer using different loads in order to assess lubrication and wear regimes. In the tests, the average of the friction coefficients (μ) obtained was μHETG = 0.072, μHLP = 0.026 and μHEPR = 0.011, besides well-defined lubrication regimes. In the wear analysis, it was observed that the highest concentrations of Zn and P additives, found in HEPR, reduced surface damage. The main wear mechanisms identified were scratching, microcracking, microploughing and detachment. Consistent with the results mentioned, the largest volume removed from the coating was with the use of HETG vegetable oil, about 41% more than HEPR.

Published
2023

19. ANARQUISMO E HACKTIVISMO: APROXIMAÇÕES A PARTIR DO WIKILEAKS E ANONYMOUS

Author

PIMENTEL, Alexandre Freire, NETTO, Milton Pereira de França, and NETO, Gabriel de Oliveira Cavalcanti

Subjects
Hacking, Hacktivismo, WikiLeaks, Anonymous, Anarquismo
Abstract

Este artigo discute a prática do hacking como expressão de um novo ativismo político, marcado pela incorporação dos hackers e das redes de comunicação. Para tanto, discute sobre as influências do anarquismo nessa militância política e remete-se aos coletivos WikiLeaks e Anonymous, a fim de identificar sua estrutura e modo de ação enquanto expressões do cyberativismo. A fim de lançar bases teóricas acerca do hacktivismo, levanta bibliograficamente reflexões sobre o tema. Conclui-se que o hacking é um novo ativismo político, pois visa a subversão da ordem de poder sobre a tecnologia e as formas de circulação de informação na sociedade global promovida pelo advento da internet., {"references":["CASTELLS, Manuel. Redes de indignação e esperança. Movimentos sociais na era da internet. Rio de Janeiro: Zahar, 2013.","COSENTINO, Carlo. O Direito do Trabalho na Revolução Informacional e nas Teorias dos Movimentos Sociais: impactos no postulado autonomia, nas relações individuais e coletivas de trabalho. 2017. Tese (Doutorado em Direito) – Programa de Pós-Graduação em Direito, Universidade Federal de Pernambuco, Recife, 2017.","FOUCAULT, Michael. Vigiar e punir: nascimento da prisão. Tradução Lígia M. Pondé Vassalo. Petrópolis, RJ: Vozes, 1977","ZERZAN, J. ‎Future Primitive: And Other Essays (Autonomedia New Autonomy). New York: Autonomedia, 1994.","GREEN ANARCHY COLLECTIVE. What is green anarchy? An introduction to anti-civilization anarchist thought and practice. Back to Basics, [s. l.], v. 4, n. 17, p. 35–41, 2004.","BOOKCHIN, Murray. Social Anarchism or Lifestyle Anarchism: an unbridgeable chasm. San Francisco, CA: AK Press, 1995. Disponível em: https://libcom.org/files/Social%20Anarchism%20or%20Lifestyle%20Anarchism.pdf. Acesso em: 15 jul. 2021.","JORDAN, Tim. Hacktivism: All Together in the Virtual. In: JORDAN, Tim. Activism!: Direct Action, Hacktivism and the Future of Society. London, UK: Reaktion Books Ltd., 2002. p. 119-137.","NAUGHTON, John. A brief history of the future: from radio days to Internet years in a lifetime. Woodstock, NY: Overlook Press. 2000.","EVANGELISTA, Rafael. O movimento software livre do brasil: política, trabalho e hacking. Horizontes Antropológicos, Porto Alegre, ano 20, n. 41, p. 173-200, jan./jun. 2014.","TAYLOR, Paul. A. Editorial: Hacktivism. The Semiotic Review of Books, [online], v. 12, n. 1, p. 1-9, 2001. Disponível em: http://projects.chass.utoronto.ca/semiotics/srb/Hacktivism.pdf. Acesso em: 15 jul. 2021.","CONWAY, Maura. Hackers as Terrorists? Why It Doesn't Compute? Computer Fraud and Security, United Kingdom, n. 12, p. 10-13, 2003. Disponível em: http://doras.dcu.ie/493/1/comp_fraud_12_2003.pdf. . Acesso em: 15 jul. 2021.","TAYLOR, Paul A. From Hackers to Hacktivists: Speed Bumps on the Global Superhighway?. New Media Society, United Kingdom, v. 7, n. 5, p. 625-646, 2005. Disponível em: http://atc.berkeley.edu/201/readings/PTaylor.pdf. Acesso em: 15 jul. 2021.","PAPADIMITRIOU, Fivos. A Geography of 'Notopia': Hackers et al., Hacktivism, Urban Cyber-Groups/Cyber-Cultures and Digital Social Movements. City, United Kingdom, v. 10, n. 3, p. 317-326, 2006. Disponível em: http://www.tandfonline.com/doi/pdf/10.1080/13604810600982289. Acesso em: 15 jul. 2021.","VAN LAER, Jeroen; VAN AELST, Peter. Internet and Social Movement Action Repertories: Opportunities and Limitations. Information, Communication & Society, United Kingdom, v. 13, n. 8, p. 1146-1171, 2010. Disponível em: http://www.academia.edu/262038/Internet_and_Social_Movement_Action_Repertoires_Opportunities_and_Limitations. Acesso em: 15 jul. 2021.","BEYER, Jessica L. The Emergence of a Freedom of Information Movement: Anonymous, WikiLeaks, the Pirate Party, and Iceland. Journal of Computer- Mediated Communication, Oxford, v. 19, n. 2, p. 141-154, 2014. Disponível em: http://onlinelibrary.wiley.com/doi/10.1111/jcc4.12050/abstract. Acesso em: : 15 jul. 2021.","FITRI, Nofia. Democracy Discourses Through the Internet Communication: Understanding the Hacktivism for the Global Changing. Online Journal of Communication and Media Technologies. 1(2): 1-20. 2011. Disponível em: http://www.academia.edu/1344217/Democracy_Discourses_through_the_Interne t_Communication_Understanding_the_Hacktivism_for_the_Global_Changing. Acesso em: 15 jul. 2021.","KRAPP, Peter. Terror and Play, Or What Was Hacktivism?. Grey Room, Massachusetts, n. 21, p. 70-93, 2005. Disponível em: http://www.academia.edu/307639/Terror_and_Play_or_What_Was_Hacktivism. Acesso em: 15 jul. 2021.","GILLEN, Martina. Human Versus Inalienable Rights: Is There Still a Future for Online Protest in the Anonymous World? European Journal of Law and Technology, Belfast, v. 3, n. 1, p. 1-19, 2012. Disponível em: http://eprints.uwe.ac.uk/21065/1/Gillen%20Human%20Rights.pdf. Acesso em: 15 jul. 2021.","WRAY, Stefan. Electronic Civil Disobedience and the World Wide Web of Hacktivism: A Mapping of Extraparliamentarian Direct Action Net Politics. Switch, Switzerland, v. 4, n. 2, 1998. Disponível em: http://switch.sjsu.edu/web/v4n2/stefan/. Acesso em: 15 jul. 2021.","JORDAN, Tim; TAYLOR, Paul. A Sociology of Hackers. The Sociological Review, United Kingdom, v. 46, n. 4, p. 757-780, 1998. Disponível em: http://onlinelibrary.wiley.com/doi/10.1111/1467-954X.00139/abstract. Acesso em: 15 jul. 2021","FUCHS, Christian. Anonymous: Hacktivism and Contemporary Politics. In: TROTTIER, Daniel; FUCHS, Christian (ed.). Social Media, Politics and the State. New York: Routledge, 2014. p. 88-106.","MANION, Mark; GOODRUM, Abby. Terrorism or Civil Disobedience: Toward a Hacktivist Ethic. ACM SIGCAS Computers and Society, [s. l.], v., 30, n. 2, p. 14-19, 2000; Disponível em: http://www.csis.pace.edu/cis101/CIS_101_Fall_2007_Spring_2008/LearningPodTopics/SocialResponsibility/Terrorism-or-Civil-Disobedience.pdf. Acesso em: 15 jul. 2021.","HIMMA, Kenneth Einar. Hacking As Politically Motivated Digital Civil Disobedience: Is Hacktivism Morally Justified?. Social Science Research Network, United States, p. 1-24, 2005. Disponível em: http://papers.ssrn.com/sol3/papers.cfm?abstract_id=799545. Acesso em: 15 jul. 2021.","LEVY, Steven. Hackers: Heroes of the Computer Revolution. Sebastopol: O'Reilly Media, Inc., 2010.","LIRA, Isadora Teixeira de. Hacktivismo e organizações midiáticas: hackeamento de narrativas em WikiLeaks e mídia ninja. 2017. 105 f. Dissertação (Mestrado em Comunicação) – Programa de Pós-Graduação em Comunicação, Universidade Federal da Paraíba, João Pessoa, 2017.","LÉVY, Pierre (1996). O Que é Virtual?. Rio: Editora 34.","YIP, Michael; WEBBER, Craig. Hacktivism: A Theoretical and Empirical Exploration of China's Cyber Warriors. In: ACM WEB SCIENCE, 3., 2011, Koblenz. Proceedings […]. Koblenz: University of Southampton, 2011. Disponível em: https://eprints.soton.ac.uk/272350/2/hacktivism.pdf/. Acesso em: 15 jul. 2021.","FUCHS, Christian. The Anonymous Movement in the Context of Liberalism and Socialism. A Journal For and About Social Movements, v. 5, n. 2, p. 345-376, 2013. Disponível em: http://fuchs.uti.at/wp-content/Interface.pdf. Acesso em: 15 jul. 2021.","FUCHS, Christian. \"The Anonymous Movement in the Context of Liberalism and Socialism.\" A Journal For and About Social Movements 5(2): 345-376. Disponível em: (http://fuchs.uti.at/wp-content/Interface.pdf). Acesso em 15 de julho de 2021. 2013.","HEARN, Kay; MAHNCKE, Rachel J.; WILLIAMS, Patricia A. Culture Jamming: From Activism to Hacktivism. Australia: Cowan University, 2009. Disponível em: http://ro.ecu.edu.au/cgi/viewcontent.cgi?article=1002&context=isw. Acesso em: 15 jul. 2021.","MONGE, Yolanda. EUA acusam Assange de conspirar para se infiltrar em sistemas do Governo com informação classificada. El País, Washington, 11 abr. 2019. Disponível em: https://brasil.elpais.com/brasil/2019/04/11/internacional/1554994445_197405.html. Acesso em: 10 jan. 2022.","WONG, Wendy H.; BROWN, Peter A. E-Bandits in Global Activism: WikiLeaks, Anonymous, and the Politics of No One. American Political Science Association, United States, v. 11, n. 4, p. 1015-1033, 2013. Disponível em: http://politics.utoronto.ca/wp-content/uploads/2013/12/wong-and-brown-2013.pdf. Acesso em: 15 jul. 2021.","COLEMAN, Gabriella. Anonymous in Context: The Politics and Power behind the Mask. Waterloo: CIGI, 2013. Disponível em: http://www.cigionline.org/sites/default/files/no3_8.pdf. Acesso em: 15 jul. 2021.","HAI-JEW, Shalin. Action Potentials: Extrapolating an Ideology from the Anonymous Hacker Socio-Political Movement (A Qualitative Meta-Analysis). In: AKRIVOPOULOU, Christina; GARIPIDIS, Nicolaos. Digital Democracy and the Impact of Technology on Governance and Politics: New Globalized Practices. Hershey, PA: Information Science Reference, 2013. p. 51-107. Disponível em: http://krex.k-state.edu/dspace/bitstream/handle/2097/15352/Hai-JewIGI2013.pdf?sequence=1. Acesso em: 15 jul. 2021.","PORTAL DE NOTÍCIAS G1, 2020. Disponível em: https://g1.globo.com/politica/noticia/2020/06/02/grupo-de-hackers-vaza-em-rede-social-supostos-dados-pessoais-de-bolsonaro-filhos-e-apoiadores.ghtml. Acesso em 14 jul. 2021."]}

Published
2023
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20. A Thermal Analysis of LASER Beam Welding Using Statistical Approaches

Author

Silva, Ariel Flores Monteiro de Oliveira, Elisan dos S. Magalhães, Luiz E. dos S. Paes, Milton Pereira, and Leonardo R. R. da

Subjects
LASER welding, heat transfer simulation, parameter optimization, Taguchi’s design, parallel computing, Compute Unified Device Architecture (CUDA-C)
Abstract

Implementing input parameters that match the experimental weld shape is challenging in LASER beam welding (LBW) simulation because the computed heat input and spot for temperature acquisition strongly affect the outcomes. Therefore, this study focuses on investigating the autogenous LBW of AISI 1020 using a three-dimensional heat transfer model that assumes a modified Gaussian heat flux distribution depending on LASER power (Qw), radius (R), and penetration (hp). The influence of such variables on the simulated weld bead was assessed through analysis of variance (ANOVA). The ANOVA returns reliable results as long as the data is normally distributed. The input radius exerts the most prominent influence. Taguchi’s design defined the studied data reducing about 65% of the simulations compared to a full factorial design. The optimum values to match the computed outcomes to lab-controlled experiments were 2400 W for power (80% efficiency), 0.50 mm for radius, and 1.64 mm for penetration. Moreover, the experimental errors regarding thermocouples positioning were corrected using linear interpolation. A parallel computing algorithm to obtain the temperature field reduces computational costs and may be applied in real-world scenarios to determine parameters that achieve the expected joint quality. The proposed methodology could reduce the required time to optimize a welding process, saving development and experimental costs.

Published
2023
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22. Lack of fusion mitigation in directed energy deposition with laser (DED-L) additive manufacturing through laser remelting

Author

Luiz Eduardo dos Santos Paes, Milton Pereira, Louriel Oliveira Vilarinho, Fabio Antonio Xavier, and Walter Lindolfo Weingaertner

Subjects
Materials science, Strategy and Management, Substrate (electronics), Management Science and Operations Research, Inconel 625, Laser, Industrial and Manufacturing Engineering, law.invention, Hot isostatic pressing, law, Fiber laser, Deposition (phase transition), Composite material, Inconel, Dispersion (chemistry)
Abstract

The void level of a component produced by additive manufacturing can be used to predict the mechanical properties and in most cases it is important to develop processing methodologies able to minimize it. Conventional techniques include parameter optimization and the hot isostatic pressing (HIP). However, in the former there is a limit where improvement becomes minimal and the latter, although it is effective for internal voids, is not efficient in the case of voids located near the surface, which are considered critical. This paper describes a study in which laser remelting was used as an alternative to achieve higher densification after processing using directed energy deposition with laser (DED-L). This technique has been investigated for powder bed (PB) processes, but has not been explored for DED. Understanding the behavior of different materials considering the same processing parameters is also relevant and has not been previously addressed. An ytterbium (Yb) fiber laser with a maximum nominal power of 10 kW and wavelength of 1070 nm was used. Iron and Inconel 625 powders were deposited on an SAE 1010 steel substrate to form beads with intentional voids. The DED-L was performed with a power of 450 W, scanning speed of 600 mm/min and powder feed rate of 10 g/min. The laser radiation was applied over the produced surface at three energy levels: 31.5 kJ/m, 38.2 kJ/m and 45 kJ/m. An in-house MATLAB image processing code was developed in order to assess the void percentage. The results indicated that most of the voids originating from the DED-L process were due to lack of fusion between beads and between the deposit and the substrate. For iron, the void percentage after DED-L varied between 5.3% and 7.1%. After remelting, this value reduced to 1.7% applying 45 kJ/m. It was also noted that in all samples the voids that were initially connected to the surface coalesced because of material redistribution. However, a low repeatability was observed. For Inconel, the void percentage after DED-L varied between 4.4% and 7.1%, and reduced to 3.7% applying 31.5 kJ/m. This reduction is not as significant as that observed for iron and also the degree of dispersion was lower for iron. Hence, laser remelting is able to mitigate voids resultant from DED-L and, consequently, achieve better quality due to a lower probability of component failure. Simultaneously, productivity can be enhanced since the equipment required is the same as that used for the deposition. However, new strategies are needed to increase the process robustness and reduce the degree of dispersion.

Published
2022

25. Understanding the behavior of laser surface remelting after directed energy deposition additive manufacturing through comparing the use of iron and Inconel powders

Author

Ana Sofia C. M. D’Oliveira, Erick Cardoso Costa, Luiz Eduardo dos Santos Paes, Milton Pereira, Louriel Oliveira Vilarinho, Américo Scotti, Fabio Antonio Xavier, and Walter Lindolfo Weingaertner

Subjects
Materials science, Waviness, Strategy and Management, Metallurgy, Surface finish, Management Science and Operations Research, Laser, Inconel 625, Thermal diffusivity, Industrial and Manufacturing Engineering, law.invention, Machining, law, Surface roughness, Inconel
Abstract

Laser directed energy deposition with powder (pDED-L) is one of the most popular techniques for additive manufacturing. However, for some applications, the resulting surface finish requires post-processing machining. Laser remelting processing has been cited as a means of decreasing machining needs in other applications. The objective of this study was to assess the performance and gain a better physical understanding of the laser remelting process as an alternative to the conventional post-processing techniques applied after pDED-L. pDED-L and remelting were performed using a 10 kW fiber laser source and iron and Inconel 625 powders as feedstock to compare the surface roughness and waviness under different processing conditions (three heat input levels). Through 2D and 3D surface measurements, as well as scanning electron microscopy (SEM), surface features were qualified and quantified. SEM and optical microscopy (OM) were also employed for metallurgical characterization of the roughness. The surface micro-notch effect was assessed through the stress concentration factor (kt). The results indicated attenuation of the average roughness (Ra) by around 30% for iron and 70% for Inconel when laser remelting was employed. In addition, kt presented a 31% reduction for iron and 29% reduction for Inconel. The performance varied according to the type of material used and was mainly related to differences in thermal diffusivity and electrical resistivity. It was concluded that laser remelting is a promising technology for coupling with pDED-L aimed at producing 3D metal components with superior quality while allowing a faster production rate in comparison to current practices.

Published
2021

26. The IRAK4 scaffold integrates TLR4-driven TRIF and MYD88 signaling pathways

Author

Milton Pereira, Danielle F. Durso, Clare E. Bryant, Evelyn A. Kurt-Jones, Neal Silverman, Douglas T. Golenbock, Ricardo T. Gazzinelli, Bryant, Clare [0000-0002-2924-0038], Apollo - University of Cambridge Repository, and Pereira, Milton [0000-0003-2977-1565]

Subjects
LPS, IRAK, CP: Immunology, macrophage, General Biochemistry, Genetics and Molecular Biology, Gram-negative, Toll-Like Receptor 3, Toll-Like Receptor 4, Adaptor Proteins, Vesicular Transport, Interleukin-1 Receptor-Associated Kinases, Toll-like receptor, TLR, Myeloid Differentiation Factor 88, cell signaling, Humans, NF-kB, innate immunity, TRAF6, Adaptor Proteins, Signal Transducing, Signal Transduction
Abstract

Funder: Conselho Nacional de Desenvolvimento Científico e Tecnológico, Funder: Fundação de Amparo à Pesquisa do Estado de Minas Gerais, Interleukin-1 receptor-associated kinases (IRAKs) -4, -2, and -1 are involved in transducing signals from Toll-like receptors (TLRs) via the adaptor myeloid differentiation primary-response protein 88 (MYD88). How MYD88/IRAK4/2/1 complexes are formed, their redundancies, and potential non-enzymatic roles are subjects of debate. Here, we examine the hierarchical requirements for IRAK proteins in the context of TLR4 activation and confirmed that the kinase activity of IRAK4 is essential for MYD88 signaling. Surprisingly, the IRAK4 scaffold is required for activation of the E3 ubiquitin ligase TNF receptor-associated factor 6 (TRAF6) by both MYD88 and TIR domain-containing adaptor protein inducing IFN-β (TRIF), a unique adaptation in the TLR4 response. IRAK4 scaffold is, therefore, essential in integrating MYD88 and TRIF in TLR4 signaling.

Published
2022

27. Os 'selvagens bruxos' do Araguaia Paraense: Representações discursivas missionárias na Revista Cayapós e Carajás

Author

Milton Pereira Lima and Idelma Santiago da Silva

Subjects
General Medicine
Abstract

Este artigo versa sobre as representações discursivas dos missionários dominicanos em relação aos indígenas do Araguaia Paraense, tendo como fonte a Revista Cayapós e Carajás (RCC), editada entre 1922 e 1933. O ponto de partida são os enunciados dos missionários representados como acusações de que os indígenas seriam “selvagens” e praticantes de “bruxarias e curandeirismo”. Todavia, essas nomeações, classificações e rótulos colaboravam com a ação pacificadora, clerical e leiga, que pretendia convencer que o batismo apagaria as práticas “do feitiço e do feiticeiro”; e a catequese transfiguraria o indígena em “cidadão/cristão”. A eliminação do paganismo dos Cayapós e Carajás, englobando também outros grupos, deveria, em última instância, resultar na “conversão” dos indígenas aos costumes ocidentais. O funcionamento discursivo desenrolava-se no combate a autoridade dos “velhos”, “velhas” e “pajés”, a fim de quebrar sua hierarquia e influência social. A análise discursiva sobre a materialidade da documentação, antecedida da metodologia de tematização e classificação de “recortes” do periódico, orientou-se nas formulações teóricas de Bakhtin (1997; 2006) e Orlandi (1990), entre outros, para dimensionar os “signos ideológicos” e “praticas divisoras”, articulados dentro de um dado campo cultural.

Published
2021

30. O colégio Santa Rosa na dinâmica da 'Educação-Pacificação' dos 'Selvagens' do Araguaia paraense, a partir da revista Cayapós e Carajás/Memória Dominicana (1902-1952)

Author

Milton Pereira Lima

Abstract

No presente artigo foi realizada uma investigação a respeito do Colégio Santa Rosa, sua fundação e o perfil dos seus estudantes. O surgimento de tal instituição foi articulado por padres dominicanos do Araguaia Paraense, se tornando um marco educacional na fronteira do Araguaia Paraense, que atendia crianças indígenas de variados grupos étnicos, moradores do imenso território de Conceição do Araguaia. Utilizou-se como fonte a narrativa constituinte da revista Cayapós e Carajás/Memória dominicana, além de corpus documentais produzidos pelos missionários entre os anos de 1902 a 1952. O resultado da criação dessa escola foi a articulação de uma educação de perfil elementar para formar cidadãos cristãos. Todavia, se objetivou uma adequação do comportamento dos indígenas ao padrão cultural ocidental, o que ajudou na promoção da “pacificação”, na evacuação e na extinção de grupos indígenas araguaianos.

Published
2021

31. Incidência de traumas raquimedulares causados por acidentes de trânsitos no nordeste de 2020 a 2022: Uma análise transversal

Author

Romerio Alves Soares, Felipe Bezerra Zabulon de Figueiredo, Pedro Alves Leal Neto, Wanderson Souza Pais, João Victor Araújo Ciriaco Amaral, Gabriel Albuquerque de Lucena, Márcio Elon Ferreira de Souza Filho, José Milton Pereira Neto, Guilherme Henrique de Ataíde Melo, and Antônio Ferreira de Souza Neto

Subjects
General Earth and Planetary Sciences, General Environmental Science
Abstract

Tendo em vista, as altas taxas de acidentes automobilísticos ocorridos na região nordeste, especialmente levando em consideração a incidência de internações pelo fato dos Traumas Raquimedulares, ressalta-se portanto, a importância deste estudo, dada na qual os acidentes de trânsito são uma das principais causas de mortalidade. Assim, o objetivo da pesquisa foi avaliar a incidência dos casos de Traumas Raquimedulares causados por acidentes de trânsitos na região nordeste. O método utilizado para o estudo foi uma análise transversal. A realização da coleta de dados ocorreu entre os meses de Janeiro e Fevereiro de 2023, utilizando o Sistema de Informações Hospitalares do SUS (SIH/SUS) e o Banco de Dados do Sistema Único de Saúde (DATASUS). Os resultados obtidos apontam que a região que menos notificou os casos de TRM foi a região Centro-Oeste, com um resultado total de 514 casos confirmados nos últimos 3 anos. Estes dados apontam à necessidade de intensificar e delimitar estes achados, visto que, é necessário conhecer os principais fatores responsáveis por estes resultados e delimitar os Estados que mais possuem evidências e notificações de Acidentes de Trânsitos com Traumas Raquimedulares. Nesse desfecho, delimitou-se as pesquisas, utilizando-se os Estados da região nordeste para avaliar as notificações.

Published
2023

32. Effect of power modulation frequency on porosity formation in laser welding of SAE 1020 steels

Author

Luiz Fernando Bossa, Luiz Eduardo dos Santos Paes, Francisco Cavilha Neto, Márcio Celso Fredel, and Milton Pereira

Subjects
0209 industrial biotechnology, Materials science, Mechanical Engineering, Laser beam welding, 02 engineering and technology, Square wave, Welding, Industrial and Manufacturing Engineering, Computer Science Applications, law.invention, 020901 industrial engineering & automation, Control and Systems Engineering, law, Weld pool, Composite material, Penetration depth, Porosity, Frequency modulation, Keyhole, Software
Abstract

This study aimed to assess and to understand the effect of modulation frequency on weld bead porosity. A fiber laser source with a maximum power of 10 kW was used on SAE 1020 plates. A square wave modulation with pulse power at 4 kW and base power at 0 kW was applied, which resulted in a power average of 2 kW. Welding speed was set at 1 m/min, and frequency varied from 20 to 100 Hz. To analyze the pores, longitudinal cross-sections were prepared. The results indicate that the welds produced at low frequencies (20 Hz and 25 Hz) contained a significant amount of large spherical pores. On the other hand, a reduced number of smaller pores were found for high frequencies (50 Hz and 100 Hz). This can be correlated to the penetration depth oscillation, linked to the weld pool fluid flow and the keyhole collapse, which was greater at lower frequencies. In addition, other effects could be noted, such as the widening of the weld bead for low-frequency values, which can be beneficial when the process requires low geometrical tolerances and higher penetration depths for increased degrees of overlap at higher frequencies.

Published
2021

33. Wear resistance of a Metco 1030A hard coating deposited on Hadfield steel by laser cladding for ore comminution application

Author

Alexsandro Rabelo, Milton Pereira, Leandro João da Silva, Moisés Felipe Teixeira, Jeferson T. Pacheco, and Carlos E. Niño

Subjects
0209 industrial biotechnology, Materials science, Mechanical Engineering, Metallurgy, Alloy, 02 engineering and technology, engineering.material, Microstructure, Indentation hardness, Industrial and Manufacturing Engineering, Computer Science Applications, Carbide, Grinding, 020901 industrial engineering & automation, Coating, Control and Systems Engineering, engineering, Comminution, Laser power scaling, Software
Abstract

The premature wear and/or failure of components and equipment used for ore comminution can result in unscheduled downtime and, therefore, significant losses for the mining industry, in which it is estimated that about half of the total maintenance cost in mining is due to the manufacture of damaged parts and the other half due to downtime and labor. In this sense, approaches to improve the wear resistance of this kind of equipment are of great interest. Therefore, the present work aims to evaluate the potential of coating a high manganese Hadfield steel used to manufacture grinding hammers with Metco 1030A alloy (Fe–C–Mo–V–B) via laser cladding (DED-L). The coatings were deposited on Hadfield steel substrates (cast) using different levels of laser power and scanning speed. The coatings were characterized in relation to the presence of surface and internal defects, morphology, microstructure, chemical composition, and microhardness. The wear resistance of the coatings was evaluated by pin-on-drum tests. For all deposition conditions, continuous tracks were formed. Despite the superficial cracks, the layers did not detach, confirming the metallurgical bond with the substrate. The microstructure of the coatings is typically composed of vanadium carbides (VCs) and molybdenum borides (Mo2B) in a martensitic matrix. For the same scanning speed, carbides and borides tend to become larger and more widely spaced with increasing laser power. Compared with the Hadfield steel substrate, the coatings have significantly higher hardness and wear resistance. Despite the cracks, normally acceptable in the intended application, it can be said that the application of the Metco 1030 alloy via laser cladding has the potential to increase the service life of Hadfield grinding hammers.

Published
2021

34. MEDIAÇÕES INTERÉTNICAS NA FRONTEIRA DA AMAZÔNIA: MISSIONÁRIOS, INDÍGENAS E SERTANEJOS NO ARAGUAIA PARAENSE - (1897-1952) / INTERETHNIC MEDIATIONS ON THE AMAZON FRONTIER: MISSIONARIES, INDIGENOUS AND BACKWOODSMEN IN ARAGUAIA PARAENSE - (1897-1952)

Author

Milton Pereira Lima, José Rodrigues de Carvalho, and Gilberto Ribeiro Borges

Subjects
Marketing, Pharmacology, Organizational Behavior and Human Resource Management, Frontier, Geography, Amazon rainforest, Strategy and Management, Drug Discovery, Pharmaceutical Science, Ethnology, Indigenous
Published
2021

36. A comparison between LBW and hybrid laser-GMAW processes based on microstructure and weld geometry for hardenable steels

Author

Jurandir Marcos Sá de Sousa, Milton Pereira, Mateus Barancelli Schwedersky, Bruno Borges Ramos, Régis Henrique Gonçalves e Silva, Max Baranenko Rodrigues, Caroline Mano Monteiro de Paço, and Rafael Gomes Nunes Silva

Subjects
0209 industrial biotechnology, Materials science, Mechanical Engineering, Metallurgy, Laser beam welding, 02 engineering and technology, Welding, Microstructure, Indentation hardness, Industrial and Manufacturing Engineering, Computer Science Applications, Gas metal arc welding, law.invention, 020901 industrial engineering & automation, Brittleness, Control and Systems Engineering, law, Laser power scaling, Arc welding, Software
Abstract

Welding processes are present in most industry sectors. Conventional arc welding processes, such as the gas metal arc welding (GMAW) process, have limitations when applied to join thick materials. In this scenario, the laser beam welding (LBW) process has proved to be an alternative to achieve high penetration depths, eliminating the need for joint beveling, although not without limitations. Proneness to surface and internal discontinuities are some of them. Recently, hybrid laser-arc welding (HLAW) process has come up as a promising joining process, combining the advantages of the GMAW and LBW processes on a single melting pool, counteracting defects, and enhancing process efficiency. Despite the high complexity of the hybrid process, its advantages derive not only from geometrical and mechanical issues but also from metallurgical features or characteristics. Twelve LBW and HLAW welding tests were performed using 5, 6, 7, 8, 9, and 10 kW of laser power. The HLAW results show higher robustness against weld defects, as well as greater penetration depths and bead widths then pure LBW. The microstructures in all regions of the welds were analyzed, showing their correlation between the welding parameters and processes performed. Due to a distinct thermal cycle resulting from the two simultaneous heat sources, the weld bead produced by the HLAW process presented reduction of 100 HV in the microhardness on the upper region and consequently reduction of its brittleness. The results obtained clearly indicate the metallurgical and operational advantages of the HLAW process compared with the individual LBW process.

Published
2020

37. Evaluation of High Penetration Hybrid Laser-GMAW Welding Process Productivity Applied in the Joining of Thick Plates and Pipelines

Author

Rafael Gomes Nunes Silva, Max Baranenko Rodrigues, Milton Pereira, and Koen Faes

Abstract

Welding processes are present in all sectors of the industry, highlighting the manufacturing industry of thick plates and pipelines. In these applications, welding processes have a major influence on costs, schedules, risk analysis and project feasibility. Conventional arc welding processes, such as the gas metal arc welding (GMAW) process, have limitations when applied to high thickness joints due to their maximum achievable penetration depth. On the other hand, the laser beam welding (LBW) welding process, despite reaching high penetration depths, has several limitations mainly regarding the geometric tolerance of the joint. In this regard, the hybrid laser-arc welding (HLAW) process emerges as a promising bonding process, combining the advantages of the GMAW and LBW processes into a single melting pool. Despite the many operational and metallurgical advantages, the HLAW process presents a high complexity due to the high number of parameters involved and the interaction between the laser beam and the electric arc. The present work discusses the challenges involved in the parametrization of the HLAW process applied to the joining of thick plates and pipes, and empirically evaluated a comparison between the HLAW and GMAW processes, showing a reduction of operating time of approximately 40 times, and a reduction of consumption of shielding gas and filler material of approximately 20 times, evidencing the technical and financial contribution of the hybrid process.

Published
2022

41. Qual deve ser o regime de responsabilidade civil aplicável à inteligência artificial no Brasil?

Author

Ehrhardt Júnior, Marcos and Netto, Milton Pereira de França

Abstract

Submitted by rcaetano@stj.jus.br (rcaetano@stj.jus.br) on 2022-06-28T21:08:07Z No. of bitstreams: 2 qual_deve_regime_ehrhardt.pdf: 186477 bytes, checksum: d7f7664fa2c88d55be150dc365741a75 (MD5) license.txt: 1239 bytes, checksum: c9b4c351324448672315a00808efb725 (MD5) Approved for entry into archive by betanial@stj.jus.br (betanial@stj.jus.br) on 2022-06-29T19:09:33Z (GMT) No. of bitstreams: 2 qual_deve_regime_ehrhardt.pdf: 186477 bytes, checksum: d7f7664fa2c88d55be150dc365741a75 (MD5) license.txt: 1239 bytes, checksum: c9b4c351324448672315a00808efb725 (MD5) Made available in DSpace on 2022-06-29T19:09:33Z (GMT). No. of bitstreams: 2 qual_deve_regime_ehrhardt.pdf: 186477 bytes, checksum: d7f7664fa2c88d55be150dc365741a75 (MD5) license.txt: 1239 bytes, checksum: c9b4c351324448672315a00808efb725 (MD5) Previous issue date: 2022

Published
2022

44. A convolutional neural network approach on bead geometry estimation for a laser cladding system

Author

Denise Albertazzi Gonçalves, Marcelo Ricardo Stemmer, and Milton Pereira

Subjects
0209 industrial biotechnology, Traverse, Materials science, Mechanical Engineering, Acoustics, Process (computing), 02 engineering and technology, Convolutional neural network, Industrial and Manufacturing Engineering, Computer Science Applications, 020901 industrial engineering & automation, Dimension (vector space), Control and Systems Engineering, Deposition (phase transition), Millimeter, Laser power scaling, Coaxial, Software
Abstract

Laser cladding is a complex manufacturing process. As the laser beam melts the feedstock powder, small changes in laser power or traverse speed reflect on deviations of the deposition’s geometry. Thus, fine-tuning these process parameters is crucial to achieve desirable results. In order to monitor and further understand the laser cladding process, an automated method for clad bead final geometry estimation is proposed. To do so, six different convolutional neural network architectures were developed to analyze the process’ molten pool image acquired by a 50-fps coaxial camera. Those networks receive both the camera image and the process parameters as inputs, yielding width and height of the clad beads as outputs. The results of the network’s performances show testing error mean values as little as 8 μm for clad beads around a millimeter in height. For the width dimension, in 95% of the cases, the error remained under 15% of the bead’s width. Plots of the target versus the estimated values show coefficients of determination over 0.95 on the testing set. The architectures are then compared, and their performances are discussed. Deeper convolutional layers far exceeded the performance of shallower ones; nonetheless, deeper densely connected layers decreased the performances of the networks when compared with shallower ones. Those results represent yet another alternative on intelligent process monitoring with potential for real-time usage, taking the researches one step further into developing a closed-loop control for this process.

Published
2019

46. O DISCURSO SOBRE OS 'SELVAGENS' NA REVISTA CAYAPÓS E CARAJÁS

Author

Lima, Milton Pereira and Ribeiro Junior, Ribamar

Abstract

Este trabalho é parte de um estudo interdisciplinar que tematiza o “discurso dos missionários dominicanos sobre os indígenas do Araguaia na Revista Cayapós e Carajás na primeira metade do século XX”. Dessa forma, o texto narra o contexto histórico das relações interétnicas na margem do Araguaia Paraense, e discute a migração e sua territorialização, tendo como referencial teórico a própria literatura dominicana, além de textos de viajantes e pesquisadores. A metodologia adotada compõe uma revisão da literatura em uma perspectiva qualitativa do corpus documental, além da classificação, sistematização e tematização, tendo os missionários, indígenas e sertanejos em situação de fronteira como foco. Ao se analisar o discurso missionário, foi possível perceber seu viés notadamente ideológico, próprio da dinâmica da representação sobre o indígena e sobre sertanejo do “Araguaia Paraense”.

Published
2021
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47. Thermocouple positioning through capacitive discharge for temperature monitoring in laser welding

Author

Luiz Eduardo dos Santos Paes, Elisan dos Santos Magalhães, Milton Pereira, Louriel Oliveira Vilarinho, and Claudio Abilio da Silveira

Subjects
Heat-affected zone, Materials science, Mechanical Engineering, Applied Mathematics, Acoustics, General Engineering, Aerospace Engineering, Laser beam welding, Overheating (economics), Welding, Temperature measurement, Industrial and Manufacturing Engineering, law.invention, law, Thermocouple, Automotive Engineering, Arc welding, Keyhole
Abstract

Temperature measurement in welding constitutes relevant information for process understanding and simulation, as it can be used to validate and predict microstructure. Monitoring can be performed at specific points through transducers. The typical one is the thermocouple. In laser welding processes, due to the high energy concentration of the beam, the acquisition with thermocouples should be performed closer to the bead when compared to electric arc welding processes. This measurement is critical because of overheating by spatters, which can result in damage. The present work covers developing a Capacitive Discharge Welding device for thermocouple fixing and assessing possible temperature acquisition positions in keyhole laser welding. The study performed all tests with a fiber laser of 9 kW power and 3 m/min scanning speed. When placed at 2 mm from the weld centerline, the results showed a high probability of spattering due to the 71° range of incidence angle. Therefore, the thermocouple should be placed far from the weld centerline to minimize the spattering. However, it must be close enough to acquire temperatures above 727 °C. This temperature corresponds to the envisaged austenitization microstructure correlation. The study found the maximum distance at 3.5 mm based on an interpolation map, where the incidence spatters angle reduced to 59°. At a 2 mm distance from the weld centerline, the weld cross section temperatures reached more than 727 °C. However, the microstructural changes did not occur due to insufficient austenitization time. The Heat Affected Zone boundary was at 1.64 mm from the weld centerline. Therefore, to correlate microstructure with thermal cycles, it is necessary to place thermocouples at a distance below this value. However, spatter can be a problem since the range of incidence angle is about 75°. Therefore, this work recommends using more than one thermocouple for each position (redundancy) to increase valuable data.

Published
2021

48. Tribological performance of Ni-Cr-B-Si coatings deposited via laser cladding process

Author

Jurandir Marcos Sá de Sousa, Adriano de Souza Pinto Pereira, Rafael Gomes Nunes Silva, Milton Pereira, Richard de Medeiros Castro, Elvys Isaías Mercado Curi, and Paulo Cordeiro Machado

Subjects
Process Chemistry and Technology, Materials Chemistry, Instrumentation, Surfaces, Coatings and Films
Abstract

Ni-Cr-B-Si alloy coatings deposited by the laser cladding process have high tribological resistance, good metallurgical bonding with the substrate, and an interesting set of mechanical properties. Aiming to correlate microstructure and the mechanical behavior of coatings in wear environments, three coatings were deposited over an ASTM A36 carbon steel substrate, them being C1 (1.05 kW–5 mm s−1), C2 (1.40 kW–21.7 mm s−1), and C3 (1.75 kW–30 mm s−1). The microstructure and microhardness of the coatings were analyzed, the former by using SEM and EDS. Ball-on-disk tests were performed to determine wear and friction coefficients. In order to evaluate the worn surfaces, SEM-EDS techniques were also employed. The different solidification rates affected the behavior of microstructure and microhardness. Coating C1, deposited with a lower cooling speed, provided a longer dwell time for the nucleation and growth of Cr-carbides (CrC) in the Ni-matrix, a factor that gave it a lower dilution, higher carbide concentration, and higher microhardness when compared to C2 and C3. In the ball-on-disk test, coatings with higher concentration and CrC size presented a higher variaton of their friction coefficient, but a lower volumetric loss and wear coefficient. Analysis of the worn surfaces showed that the CrC characteristics, deterioration of tribolayers, and coating material detachment close to the solidification cracks were the main features that change the coatings’ tribological performance.

Published
2022

49. Assessment of power modulation formats on penetration depth for laser welding

Author

Luiz Eduardo dos Santos Paes, Márcio Celso Fredel, Francisco Cavilha Neto, and Milton Pereira

Subjects
0209 industrial biotechnology, Materials science, Maximum power principle, business.industry, Mechanical Engineering, Applied Mathematics, General Engineering, Aerospace Engineering, Laser beam welding, 02 engineering and technology, Square wave, Welding, Penetration (firestop), Industrial and Manufacturing Engineering, Power (physics), law.invention, 020901 industrial engineering & automation, Optics, law, Fiber laser, Automotive Engineering, business, Penetration depth
Abstract

Penetration depth is a relevant output for laser welding, since its increment enables the joining of thick plates in one pass, thus contributing to productivity. A usual way of achieving higher penetration is utilizing heat input, increasing power, decreasing welding speed, or decreasing laser diameter. However, this approach may result in defects. Power modulation can be an alternative to reach this objective without discontinuities, but it is usually applied in a square format. It is still unclear how different power wave shapes can influence penetration. The present paper aims to assess the effect of different power modulation formats (square, triangle, and trapezium) on penetration while maintaining the same energy input (power to welding speed ratio). A YLS 10,000 fiber laser source from IPG Photonics with a nominal maximum power of 10 kW was used on SAE 1020 plates. Results show that it is possible to achieve a 77% improvement in penetration after power modulation for a 120 kJ/m energy and square wave, which is greater than found in the literature. For 240 kJ/m energy and different power wave formats, penetration level can be enhanced through time balancing on higher powers. Beads presented depth values between 18 and 67% deeper when compared to continuous emission conditions. Square and trapezium waves are recommended when penetration is envisaged.

Published
2021

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