Desenvolvimento de um programa dos elementos contornos para contato unilateral com atrito

Monografia (graduação)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Mecânica, 2013.O presente trabalho apresenta a implementação de um código numérico para análise de problemas de contato unilateral em corpos elásticos com atrito seco. Primeiramente será apresentada uma revisão bibliográfica sobre o assunto e a formulação do problema a ser trabalhada. Baseado nas formulações encontrados na bibliografia, foram desenvolvidos algoritmos utilizando o método dos elementos de contorno na imposição das condições de contato unilateral com ou sem atrito. O programa foi desenvolvido na linguagem MATLAB® e foi avaliado pela comparação com problemas com as solução analítica conhecida e também com resultados numéricos obtidos usando o método dos elementos finitos. Os resultados numéricos apresentaram boa concordância a soluções analíticas de Hertz e também com soluções numéricas obtidas pelo método dos elementos finitos. ____________________________________________________________________________ ABSTRACTThis work presents the implementation of a numerical code for the analysis of unilateral contact of elastic bodies with dry friction. First, it will be presented a literature review on the subject and the formulation of the problem to be worked. Based on the formulations found on the literature, algorithms were developed using the boundary element method with the imposition of conditions of unilateral contact with or without friction. The program was developed in MATLAB® and was assessed with problems that have known analytical solutions and with numerical results obtained by the finite element method. The numerical results showed a good agreement with Hertz analytical solutions presented in the literature for frictionless contact condition and some solutions obtained by the finite element method to problems of contact with friction

Cultures et géopolitique en Iran

Les réfugiés Afghans représentent plus de 14,5 % de la population de la province iranienne du Khorâssân. La plupart d’entre eux resteront définitivement en Iran. Cette population, étant très concentrée du point de vue géographique, ethnique et religieux, gardera ses caractères et sera difficilement assimilée. Alors que la frontière Iran-Afghanistan séparajadis les populations persanes et pashtunes, le sud du Khorâssân est devenu une région sunnite pashtunophone que les autorités iraniennes ne contrôlent quasiment plus. Désormais, le peuplement sunnite est continu de la mer d’Oman à l’Asie centrale. Cette nouvelle réalité culturelle facilite beaucoup l’influence de l’Arabie Saoudite dans ces provinces et pourrait ëtre à la source de revendications territoriales futures de l’Afghanistan, ou des pays d’Asie centrale qui voudraient obtenir un accès à la mer d’Oman. L’État iranien sera peut-être tenté de lutter contre les forces centrifuges qui poussent ces régions hors du monde persan, par une politique de dispersion des réfugiés qui veulent rester en Iran sur l’ensemble du territoire national, loin de la frontière afghane

Phage Therapy as a New Approach in Treating Emerging Antibiotic Resistant Infections

Despite the progress in treatment of infectious diseases, ability of microorganisms to develop the resistance to routine antibiotics has still remained as a big global challenge in clinics. This subject matter keeps the infections top in the list of life threatening diseases especially in those individuals suffering from nosocomial infections. The importance of this global health challenge urges researchers to find an alternative solution with more efficacies to treat infections. There are some alternative approaches by which the global spread of resistant bacteria could be controlled. Through these ways, using bacteriophages instead of different generation of antibiotics brings many promises. According to results of different studies using bacteriophages in the management of infectious disease especially in nosocomial infections not only helps to reduce the spread of antibiotics resistance but also raises the hopes for the rescue of the suffering patients. Bacteriophages can open a new therapeutic window in the control and the treatment of the infectious disease with better efficacy.HIGHLIGHTS•Bacteriophage can be used as an antimicrobial agent for treatment of bacterial infection.•Bacterial resistance to routine antibiotics is a big challenge in the world.•Specificity toward bacteria is one of the important characteristic of phages

Synergistic Antiparkinsonian Effect of Flunarizine, Glibenclamide and B Vitamins in a Rate 6-Hydroxydopamine Model; The Role of Malondialdehyde

Background: The current study evaluated the effects of a combination of flunarizine (flu) a calcium channel blocker, glibenclamide (Glib), a KATP channels blocker and B vitamins (B com) on the behavioral symptoms of 6-hydroxydopamine (6-OHDA)-induced model of Parkinson disease to evaluate the synergistic antiparkinsonian effects of the drugs and supplements. Also the level of malondialdehyde (MDA) was measured in blood and brain suspensions to find probable neuroprotective mechanism of these materials. Methods: 6-OHDA was injected into striatum of rats by stereotaxic surgery. Pretreatment with flu, Glib and B com was started before the surgery and continued to three weeks after the surgery. Development and severity of Parkinson disease were evaluated by the conventional behavioral tests. MDA values were measured spectrophotometrically, using thiobarbituric acid test and the MDA standard curve. Results: Pretreatment with a combination of flu, Glib and B com ameliorated the behavioral symptoms of Parkinson disease. The effect of the combination was significantly more potent than those of flu, Glib or B com, solely. Pretreatment with the combination or using only Glib or B com separately, reduced the level of MDA in blood and brain, significantly. However, the effect of the combination was significantly more potent than those of Glib or B com, solely. Conclusions: Since the severity of the behavioral symptoms in the 6-OHDA-induced model of Parkinson disease reflects the degree of the lesion in substantia nigra (SN) dopaminergic neurons, it is suggested that using the combination had neuroprotective effects. The obtained data suggest a synergistic neuroprotective and antiparkinsonian effect for flu, Glib and B com. At least, a part of this effect was mediated through inhibition of oxidative stress. Keywords: 6-Hydroxydopamine, Flunarizine, Glibenclamide: B Vitamins, Behavioral Symptoms, Malondialdehyd

The Toxicity of Synthetic and Biogenic Selenium Nanoparticles on Human Brain Glioblastoma Cell Line: An in vitro Comparison

Background: Brain tumors can be serious and life-threatening when they are treated effectively. Many therapeutic approaches, such as chemotherapy, radiotherapy, and surgery have been used to treat brain tumors. In this regard, selenium supplements have been reported effective.Methods: Selenium Nanoparticles (SeNPs) were produced in two forms of synthetic and biogenic to evaluate their cytotoxicity on brain glioblastoma cell lines. A-172 cell line was cultured in DMEM medium. The cytotoxicity of the synthetic and biogenic SeNP was assessed by MTT assay. Results: There was a significant difference between the group treated with biogenic and synthetic SeNP compared with non-treated cells after 24, 48, and 72 h. Both biogenic and synthetic SeNP increased Bax gene and decreased Bcl-2 gene expression. Conclusion: It seems that biogenic SeNP was more lethal than its synthetic form. Therefore, it should be considered that the method of NP construction may be an important parameter for its bioactivity

STRATIGRAPHY OF THE LOWER OLIGOCENE NUMMULITIC LIMESTONES, NORTH OF SONQOR (NW IRAN)

The lower Oligocene hyaline and porcellaneous larger foraminifera of a carbonate platform setting, north of Sonqor, were studied for high-resolution biostratigraphy in the context of European standard zonation (Shallow Benthic Zones). According to the geological map of Kermanshah, these beds were previously ascribed to the Miocene. The identified larger foraminifera include Nummulites fichteli Michelotti, Nummulites vascus Joly & Leymerie, Operculina complanata (Defrance), Asterigerina rotula (Kaufmann), Planorbulina bronnimanni Bignot & Decrouez, Discogypsina discus (Goës), Gypsina mastelensis Bursch, Halkyardia maxima Cimerman, Stomatorbina concentrica (Parker & Jones), Praerhapydionina delicata Henson, Penarchaias glynnjonesi (Henson), Austrotrillina aff. paucialveolata Grimsdale, and Haddonia heissigi Hagn, associated with the coralline alga Subterraniphyllum thomasii Elliott. The foraminiferal association characterises the SBZ 21 Zone (early Rupelian)

Ground state of the staggered Heisenberg-Γ\Gamma honeycomb model in a magnetic field

We study the ground state properties of the $S=\frac{1}{2}$ staggered Heisenberg-$\Gamma$ honeycomb model under a magnetic field based on analytical and numerical methods. Our calculations show that the conventional zigzag and stripy phases are favored because of the staggered Heisenberg interaction away from the pure $\Gamma$ limit. In our classical analysis, we find that the field induces a series of competing magnetic phases with relatively large unit cells in the region sandwiched between the two magnetic phases with long-range ordering. In the quantum treatment, these large magnetic unit cells are destabilized by strong quantum fluctuations that result in the stabilization of a gapless quantum spin liquid behavior. In a honeycomb $\Gamma$ magnet, we disclose an intermediate-field gapless quantum spin liquid phase driven by a tilted field away from the out-of-plane direction only for a narrow region between the low-field zigzag and high-field fully polarized phases.Comment: 12 pages, 12 figure

Glucomannan enhanced the macrophage activity in exposure to methicillin-resistant Staphylococcus aureus (MRSA): in-vitro study

Background and Objectives: The increasing number of methicillin-resistant Staphylococcus aureus persuade the need for preventive measures. Glucomannan is a polysaccharide choice for developing immunological strategies. This study aimed to investigate changes in gene expression and phagocytic activity of macrophage cells in the presence of glucomannan. Materials and Methods: The effect of different concentrations of glucomannan (25, 50, and 100 µg/mL) on the phagocytic activity of macrophage cells was measured using the colony count method. The expression of Tumor Necrosis Factor-alpha (TNF-α) and Inducible Nitric Oxide Synthase (iNOS) genes was evaluated by Real-Time PCR. Results: The concentrations of glucomannan significantly reduced the bacterial Colony-Forming Unit (CFU) and increased the phagocytic activity of macrophage cells. The maximum effect of glucomannan on iNOS and TNF-Α genes expression was 100 µg/mL. Conclusion: Glucomannan should be considered an adjuvant that stimulates the immune system. It may increase the expression of TNF-α and iNOS genes and the phagocytic activity of macrophage cells against methicillin-resistant Staphylococcus aureus

Axial-torsional dynamics of a drilling bit with non-uniform blade arrangement

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