Evaluation of standard API casing connections and parametric API buttress improvement by finite element analysis.

Threaded and coupled connections generally present a non-uniform stress distribution, which is related to the higher stiffness of the box when compared to the pin. The non-uniform stress distribution can contribute to fatigue cracks and other failure modes in high pressure oil wells. An API 5CT P110 steel obtained from a seamless pipe was mechanically characterized. FEA models were carried out to investigate and compare two API casing connections under make-up torque and tensile efforts. A parametric study was performed using numerical models to determine the influence of some geometric features on the behavior of the API Buttress threaded connection. The API Buttress connection supported higher tensile loads than the API Short Round, however both standard connections showed high stress concentration in the last engaged thread and a non-uniform stress distribution. The manufacturing of grooves at the first and the last engaged threads proved to be an efficient way to reduce the stress concentration of Buttress casing connection and could be an alternative to the development of new products

Recommendations of Neuroendocrinology Department from Brazilian Society of Endocrinology and Metabolism for diagnosis and treatment of acromegaly in Brazil

A acromegalia é uma doença associada à elevada morbidade e à redução da expectativa de vida. Em virtude do seu caráter insidioso e do seu não reconhecimento, o diagnóstico é frequentemente realizado com atraso, o que, associado às complicações relacionadas ao excesso do GH/IGF-I, determina elevada morbimortalidade. No entanto, um diagnóstico precoce e um tratamento efetivo minimizam a morbidade e normalizam a taxa de mortalidade. Nesta publicação, o objetivo do Departamento de Neuroendocrinologia da Sociedade Brasileira de Endocrinologia e Metabologia é divulgar quando suspeitar clinicamente da acromegalia e como diagnosticá-la. Além disso, discute-se a maneira mais eficaz e segura de realizar o tratamento da acromegalia, enfatizando que este deve ser realizado em centros de referência. Assim, com base em dados publicados em periódicos de nível científico reconhecido e na experiência dos autores, são apresentadas as recomendações para o diagnóstico e tratamento da doença.Acromegaly is a disease associated with increased morbidity and reduced life expectancy. Because of its insidious character and its non-recognition, the diagnosis is often made with delay, which, along with the complications related to GH/IGF-I excess, determines high morbidity and mortality. However, an early diagnosis and an effective treatment reduce the morbidity and normalize the mortality rate. In this publication, the goal of Neuroendocrinology Department from Brazilian Society of Endocrinology and Metabolism is to disclose which clinical set should arouse the suspicious of acromegaly and how to diagnose it. Furthermore, we discuss the most effective and safe approach to perform the treatment of acromegaly, emphasizing that it must be carried out in reference centers. Therefore, based on data published in journals with recognized scientific level and authors' experience, recommendations are presented for diagnosis and treatment of the disease

Simulation of flash-butt welding process of a railway steel. Part 1 : residual stress analysis via FEM.

Trilhos longos, soldados pelo processo Flash Butt Welding (FBW), s?o a realidade das ferrovias brasileiras de m?dia e alta carga por eixo. Embora apresentem caracter?sticas desej?veis do ponto de vista do comportamento din?mico da via, as soldas s?o regi?es de descontinuidade estrutural e mec?nica onde se originam tens?es residuais, e que est?o associadas a falhas prematuras por fadiga. Simula??es num?ricas termomec?nicas, fisicamente n?o-lineares, no dom?nio do tempo, pelo M?todo dos Elementos Finitos (MEF), foram empregadas para avaliar o desenvolvimento de tens?es residuais originadas durante o processo de soldagem. Uma nova abordagem para a inclus?o do aporte de calor envolvido no processo ? proposta. Os resultados num?ricos s?o comparados a medidas experimentais de tens?es residuais superficiais e aspectos macrogr?ficos das juntas, incluindo largura da Zona Termicamente Afetada (ZTA) e dados de taxas de resfriamento. Os resultados mostram boa correla??o entre as an?lises num?ricas e medidas experimentais de tens?es residuais. Aspectos fundamentais relacionados ao desenvolvimento de tens?es residuais s?o esclarecidos a partir da correla??o entre an?lises num?rica e experimental. Ademais, verifica-se que os modelos computacionais podem ser utilizados na previs?o de pontos cr?ticos para nuclea??o de trincas por fadiga e/ou avaliar efeitos de vari?veis de processo sobre o campo de tens?es residuais.Long rails, welded by the Flash-Butt Welding (FBW) process, are the reality of the Brazilian railroads for medium and high axle loads. Although they present desirable characteristics concerning the dynamic behavior of the track, welded joints are regions of structural and mechanical discontinuity where high residual stresses originate, and, consequently, premature fatigue failures may take place. This paper employs the Finite Element Method (FEM) to carry out transient, physically non-linear thermo-mechanical analyses to evaluate residual stresses evolved in the welding process. A new approach is proposed to take into account the heat input involved in the process. The numerical results are compared to experimentally measured surface residual stresses, and to the macrographic joint aspects, including the HAZ width and cooling rate data. The results show a good correlation between the numerical and experimental measurements of residual stresses. Fundamental aspects related to the development of residual stresses are clarified, correlating numerical and experimental analyses. In addition, it is verified that the computational models can be used to predict critical crack nucleation points by fatigue, and/or to evaluate effects of process parameters on the residual stress field

Adsorption of cobalt ferrite nanoparticles within layer-by-layer films: a kinetic study carried out using quartz crystal microbalance

The paper reports on the successful use of the quartz crystal microbalance technique to assess accurate kinetics and equilibrium parameters regarding the investigation of in situ adsorption of nanosized cobalt ferrite particles (CoFe2O4-10.5 nm-diameter) onto two different surfaces. Firstly, a single layer of nanoparticles was deposited onto the surface provided by the gold-coated quartz resonator functionalized with sodium 3-mercapto propanesulfonate (3-MPS). Secondly, the layer-by-layer (LbL) technique was used to build multilayers in which the CoFe2O4 nanoparticle-based layer alternates with the sodium sulfonated polystyrene (PSS) layer. The adsorption experiments were conducted by modulating the number of adsorbed CoFe2O4/PSS bilayers (n) and/or by changing the CoFe2O4 nanoparticle concentration while suspended as a stable colloidal dispersion. Adsorption of CoFe2O4 nanoparticles onto the 3-MPS-functionalized surface follows perfectly a first order kinetic process in a wide range (two orders of magnitude) of nanoparticle concentrations. These data were used to assess the equilibrium constant and the adsorption free energy. Alternatively, the Langmuir adsorption constant was obtained while analyzing the isotherm data at the equilibrium. Adsorption of CoFe2O4 nanoparticles while growing multilayers of CoFe2O4/PSS was conducted using colloidal suspensions with CoFe2O4 concentration in the range of 10-8 to 10-6 (moles of cobalt ferrite per litre) and for different numbers of cycles n = 1, 3, 5, and 10. We found the adsorption of CoFe2O4 nanoparticles within the CoFe2O4/PSS bilayers perfectly following a first order kinetic process, with the characteristic rate constant growing with the increase of CoFe2O4 nanoparticle concentration and decreasing with the rise of the number of LbL cycles (n). Additionally, atomic force microscopy was employed for assessing the LbL film roughness and thickness. We found the film thickness increasing from about 20 to 120 nm while shifting from 3 to 10 CoFe2O4/PSS bilayers, using the 8.9 × 10-6 (moles of cobalt ferrite per litre) suspension.MCT/CNPqFINEPCAPESFUNAPEFINATE

Assessment of the genetic risks of a metallic alloy used in medical implants

The use of artificial implants provides a palliative or permanent solution for individuals who have lost some bodily function through disease, an accident or natural wear. This functional loss can be compensated for by the use of medical devices produced from special biomaterials. Titanium alloy (Ti-6Al-4V) is a well-established primary metallic biomaterial for orthopedic implants, but the toxicity of the chemical components of this alloy has become an issue of concern. In this work, we used the MTT assay and micronucleus assay to examine the cytotoxicity and genotoxicity, respectively, of an extract obtained from this alloy. The MTT assay indicated that the mitochondrial activity and cell viability of CHO-K1 cells were unaffected by exposure to the extract. However, the micronucleus assay revealed DNA damage and an increase in micronucleus frequency at all of the concentrations tested. These results show that ions released from Ti-6Al-4V alloy can cause DNA and nuclear damage and reinforce the importance of assessing the safety of metallic medical devices constructed from biomaterials

Genomics and epidemiology of the P.1 SARS-CoV-2 lineage in Manaus, Brazil

Cases of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in Manaus, Brazil, resurged in late 2020 despite previously high levels of infection. Genome sequencing of viruses sampled in Manaus between November 2020 and January 2021 revealed the emergence and circulation of a novel SARS-CoV-2 variant of concern. Lineage P.1 acquired 17 mutations, including a trio in the spike protein (K417T, E484K, and N501Y) associated with increased binding to the human ACE2 (angiotensin-converting enzyme 2) receptor. Molecular clock analysis shows that P.1 emergence occurred around mid-November 2020 and was preceded by a period of faster molecular evolution. Using a two-category dynamical model that integrates genomic and mortality data, we estimate that P.1 may be 1.7- to 2.4-fold more transmissible and that previous (non-P.1) infection provides 54 to 79% of the protection against infection with P.1 that it provides against non-P.1 lineages. Enhanced global genomic surveillance of variants of concern, which may exhibit increased transmissibility and/or immune evasion, is critical to accelerate pandemic responsiveness