477 research outputs found

    Elastic Constitutive Laws and Stability Analyses

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    In this paper, the influence of several elastic constitutive laws upon the stability analyses of plane trusses is discussed. The chosen laws are connected to the engineering strain, Green’s strain and logarithmic strain concepts. A geometrically exact nonlinear formulation for a truss bar element is developed for each of them and the correspondent tangent stiffness matrices are obtained. The stability analyses of some sample plane trusses are performed by finding the conditions when the determinant of their respective global tangent stiffness matrices is found to be zero. The first example is a symmetric two-bar structure and both limit loads and buckling loads are plotted for the full range of possible initial inclination angles of the bars for the three chosen constitutive laws. A similar truss with an extra vertical bar is studied to discuss possible material instability if Green’s strain concept is adopted

    On positioning and vibration control application to robotic manipulators with a nonideal load carrying

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    In recent years, the evolution of artificial intelligence techniques has widely grown such that it gives new ways to improve human life, not only at work but also living. Nowadays, to the human being, physical human-robot interactions (PHRIs) have been presented very important and present itself as a major challenge for the current engineering. Therefore, this work designs and analyses a two-degree-of-freedom robotic arm with flexible joints driven by a DC motor. Due to the interaction between the robot links and flexible joints, the arm may present overshoots when it is moved such that it becomes difficult to manipulate the arm. Therefore, Magnetorheological dampers (MR damper or MR brake) are attached to the links of the arm in order to control such overshoot and provide a way to adjust the mechanical limitations of the arm. The dynamics of the system will be investigated, showing the appearance of chaotic behavior due to the coupling of the manipulator to the motors. After that, the feedback control is obtained through the state-dependent Riccati equation (SDRE) aiming the control of the positioning of the manipulator and the torque applied on the MR damper. Numerical results showed that the proposed control using hybrid actuators, DC motor, and MR brake was effective to control the position and behavior of the flexible joints of the manipulators

    Museu 347

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    Um Museu no centro da Cidade de Foz do Iguaçu, PR que terá como objetivo principal a preservação histórica da região das 3 fronteiras; a conscientização ambiental pelo amplo Meio Ambiente natural dos 4 elementos da natureza e o profundo potencial cultural e turístico das 7 maravilhas da natureza, Cataratas doIguaçu

    Whipple's Disease With Neurological Manifestations: Case Report.

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    Whipple's disease (WD) is an uncommon multisystem condition caused by the bacillus Tropheryma whipplei. Central nervous system involvement is a classical feature of the disease observed in 20 to 40% of the patients. We report the case of a 62 year old man with WD that developed neurological manifestations during its course, and discuss the most usual signs and symptoms focusing on recent diagnostic criteria and novel treatment regimens.62342-

    The step of incorporation of Bacillus coagulans GBI-30 6086 into “requeijão cremoso” processed cheese does not affect metabolic homeostasis of rats

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    Dairy product consumption is a common habit in Brazil. These products present a good matrix for probiotic incorporation. Thus, in this study the feasibility of producing a probiotic "requeijao cremoso" incorporated with Bacillus coagulans GBI-30 6086 in three different steps and its metabolic effect in an animal model for 2 weeks has been evaluated. Wistar adult health rats were randomized into one to five groups (n = 8 for each group): Control (C); "requeijao cremoso" without probiotic (RC); probiotic inoculated in the milk before pasteurization at 65 degrees C/30 min (RPP); "requeijao cremoso" inoculated before the fusion step and consequently exposed to 90 degrees C/5 min (RPF); and "requeijao cremoso" inoculated after fusion step, i.e., once the product temperature reached 50 degrees C (RPAF). At the end of treatment, analysis of molecular markers of proteins of stress and antioxidant system, HSP 25, 60, 70 and 90, SOD and catalase were performed in the animals' muscles by Western Blot technique. The HSP25, HSP90 and catalase levels of C, RPP, RPF, and RPAF were similar, indicating that the homeostasis remained unchanged. The incorporation of B. coagulans GBI-30 6086 in the "requeijao cremoso" was shown to be stable and the microorganism remained viable in all steps tested. The incorporation of the probiotic strain in the fusion stage facilitated the technological process, since it allowed a better homogenization of the product and did not affect the maintenance of the metabolic homeostasis of rats10CONSELHO 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 informação302763/2014-7; 305804/2017-013/21544-9; 18/24540-8; 2019/21188-

    Therapeutic effects of avocado (Persea americana Mill.) seed powder against reproductive toxicity induced by Mancozeb (herbicide) in female rabbits

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    DATA AVAILABILITY STATEMENT : The authors declare no competing interests.Pesticides like Mancozeb are being increasingly indispensable in the control of crop pests. Unfortunately, they have been implicated in genotoxicity due to their ubiquity, toxicological properties, persistence and presence in the food chain. This study sought to evaluate the efficacy of powdered avocado seed on reproductive parameters in the management of oxidative stress in female rabbits caused by the herbicide Mancozeb. Twenty-eight female rabbits aged 7–8 months and weighing between 2780.4 g and 3143.7 g were randomly divided into four groups of seven rabbits each. Each group received for 90 consecutive days distilled water or Mancozeb associated or not with avocado seed powder orally as follows: T1: 10 ml distilled water; T2, T3 and T4: 100 mg/kg bw Mancozeb. This was followed by oral administration of 250, 500, and 0 mg/kg of avocado seed powder for T2, T3, and T4, respectively. Water and feed were distributed ad libitum. Collected data concerned growth, carcass and reproductive performances, hematological and biochemistry characteristics. Results demonstrated that pregnant and lactating female rabbits administered Mancozeb exhibited a significant decrease (P < 0.05) in food intake, body weight, and body weight gain. Female rabbits exposed to Mancozeb had a decrease in litter size and weight from birth to weaning, as well as in weaning body weight and weight increase, fertility and prolificacy rate, milk yield, and daily milk efficiency. However, administration of avocado seed powder reversed (P < 0.05) the trends in these parameters in a dose-dependent manner. The increase in relative weight of the kidney and liver, concentrations of urea, creatinine, alanine and aspartate aminotransferases, mean cell volume, white blood cells, and lymphocytes were all associated with increased Mancozeb rates (P < 0.05). On the contrary, administration of the Mancozeb caused decrease in hemoglobin (Hb), Red blood Cell (RBC) and protein content. Administration of avocado seed powder significantly (P < 0.05) ameliorated the Mancozeb effects on these parameters. Applying 500 mg/kg b.w Avocado seed powder may be suggested as an alternative therapy for reproductive defects induced by Mancozeb in female rabbits.https://www.cell.com/heliyon/homeZoology and Entomolog
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