High Pressure Characterization of the Viscous and Volumetric Behavior of Three Transmission Oils

Measurements of viscosity and density of three lubricating oils (two synthetic and one mineral) were performed. The density of these lubricants was measured at atmospheric pressure by means of a density measuring cell which works on the proven principle of the oscillating tube. Using the same device, the viscosity of these lubricants was measured at 0.1 MPa by using a rotational viscometer. The volumetric behavior of the tested lubricants at high pressure is also reported. Density was measured from 278.15 to 398.15 K up to 120 MPa with a high pressure vibrating tube densimeter. The isobaric thermal expansivity and the isothermal compressibility were determined with a Tammann–Tait equation. A falling body viscometer was used to determine the viscosity behavior at high pressure from 303.15 to 353.15 K up to 150 MPa. From the experimental data obtained in these measurements, the film pressure–viscosity coefficient of these lubricants was calculated and their ability to generate a lubricant film in rolling concentrated contacts was discussed.The authors gratefully acknowledge the funding through several projects and grants without whom this work would not have been possible: IACOBUS exchange program (2017); ENE2014-55489-C2-1-R and ENE2017-86425-C2-2-R cofinanced by the Spanish Ministry of Economy and Competitiveness and the European ERDF program; GRC ED431C 2016/001 financed by Xunta de Galicia (Spain); ED431E 2018/08 financed by Xunta de Galicia (Spain); Principia program JMLR of Xunta de Galicia (Spain); NORTE-01-0145-FEDER-000022—SciTech—Science and Technology for Competitive and Sustainable Industries, cofinanced by Programa Operacional Regional do Norte (NORTE2020), through Fundo Europeu de Desenvolvimento Regional (FEDER); LAETA under the project UID/EMS/50022/2013.S

Thermophysical and Tribological Properties of Highly Viscous Biolubricants

Two new highly viscous biodegradable oils are investigated for use in wind turbine gearboxes (BIO-G00) and in mechanical transmissions of agricultural tractors (BIO-G02). Studies on their thermophysical and tribological properties were performed. High-pressure–viscosity measurements were obtained up to 250 MPa and 363.15 K using a falling-body apparatus. The viscosity of BIO-G00 and BIO-G02 reaches maximum values of 14720 and 7072 mPa·s, respectively. The film thickness and the tribological performance, from boundary to full-fluid lubrication regimes, under a slide-to-roll ratio of 5% obtained in an EHD2 ball-on-disk test rig are reported. Film thickness has also been computed through the Hamrock and Dowson equation, considering the inlet shear heating (thermal correction factor) due to the high viscosity of both biolubricants. Differences between the experimental and theoretical film thicknesses are around 4% at 353.15 K and 14% at 303.15 K for both oils. The universal pressure–viscosity coefficients, αfilm, for both oils are lower than those of other mineral and synthetic oils. Higher friction coefficients are obtained for BIO-G00 in all of the studied lubrication regimes for the different rough disks and in the entire temperature range. A suitable wetting behavior on steel surfaces is observed for both selected oils.Spanish Ministry of Economy and Competitiveness and the Xunta de Galicia have supported this work through GRC ED431C 2020/10 and ENE2017-86425-C2-2-R projects. The authors are grateful to the BIOVESIN (PSE-420000-2008-4) partners for the advice and for providing them the samples of the vegetable formulated oils and the reference lubricants. Dr. M.J.G.G. acknowledges a postdoctoral fellowship (ED481B-2019-015) from the Xunta de Galicia (Spain), and Dr. L.d.R. acknowledges the financial support through the Margarita Salas program (Ministry of Universities, Spain). The authors express their gratitude to Dr. K.R. Harris (University of New South Wales, Australia) for his high-pressure–viscosity study of DiPEiC9 and also to M.A. Marcos from the University of Vigo for his help with rheology tests.S

Anéis vasculares na infância: diagnóstico e tratamento

Objetivo: apresentar a experiência do Serviço de Cirurgia Pediátrica do Instituto da Criança do HCFMUSP no diagnóstico e tratamento de crianças com anomalias do arco aórtico e definir a importância dos exames complementares para o diagnóstico. Métodos: estudo retrospectivo de 22 crianças com diagnóstico de compressão traqueoesofágica por anel vascular tratadas no Instituto da Criança, no período de 1985 a 2000, investigando-se dados clínicos pré e pós-operatórios, exames complementares e evolução. Resultados: a anomalia vascular mais freqüente foi artéria inominada direita anômala (10 casos), seguido de duplo arco aórtico (7 casos) e arco aórtico à direita (5 casos). Os sintomas predominantes foram respiratórios (86%) e de início precoce (76% desde o período neonatal). Entretanto, o diagnóstico definitivo na maioria dos casos (60%) só foi estabelecido após 1 ano de vida. O exame mais importante para o diagnóstico foi o esofagograma. A correção de todas anomalias foi realizada por toracotomia póstero-lateral esquerda. Não ocorreram complicações cirúrgicas. A evolução foi pior nos casos operados mais tardiamente. Todas as crianças permaneceram sintomáticas por até 6 meses, apesar de significativa melhora no pós-operatório. Conclusão: o diagnóstico de anel vascular deve ser investigado nas crianças com sintomas respiratórios de início precoce e nas "chiadoras" de difícil controle. O diagnóstico pode ser realizado de forma simples através do esofagograma. Os demais exames de imagem acrescentam poucas informações e são dispensáveis na maioria dos casos. Os sintomas respiratórios podem persistir com menor intensidade por períodos variáveis no pós-operatório.<br>Objective: To present the study carried out by the Pediatric Surgery Department of Instituto da Criança at the Medical School of Universidade de São Paulo regarding the diagnosis and treatment of children with aortic arch abnormalities and to define the role of complementary exams for diagnosis. Methods: Retrospective study of 22 patients with diagnosis of tracheoesophageal compression treated at Instituto da Criança from 1985 to 2000, analyzing pre- and postoperative clinical data, diagnostic exams and outcome. Results: The most frequent diagnosis was right aberrant innominate artery (10 cases), followed by double aortic arch (7 cases) and right aortic arch (5 cases). Respiratory symptoms (86%) and early manifestation (76% since the neonatal period) were predominant. Nevertheless, most cases (60%) had the definitive diagnosis established only after 1 year of life. The most relevant examination for the diagnosis was the esophagogram. The correction of all the anomalies was carried out through left postero-lateral thoracotomy. There were no surgical complications. The outcome was worse in patients with delayed treatment. All children remained symptomatic for up to 6 months, although they had significant improvement in the postoperative period. Conclusions: The diagnosis of vascular rings should be considered in children with early respiratory symptoms and in the wheezing baby with difficult control. The diagnosis may be established just through the esophagogram. Other image studies add few information and they are unnecessary in most cases. Less severe symptoms may persist for variable periods

NEOTROPICAL XENARTHRANS: a data set of occurrence of xenarthran species in the Neotropics

Xenarthrans – anteaters, sloths, and armadillos – have essential functions for ecosystem maintenance, such as insect control and nutrient cycling, playing key roles as ecosystem engineers. Because of habitat loss and fragmentation, hunting pressure, and conflicts with 24 domestic dogs, these species have been threatened locally, regionally, or even across their full distribution ranges. The Neotropics harbor 21 species of armadillos, ten anteaters, and six sloths. Our dataset includes the families Chlamyphoridae (13), Dasypodidae (7), Myrmecophagidae (3), Bradypodidae (4), and Megalonychidae (2). We have no occurrence data on Dasypus pilosus (Dasypodidae). Regarding Cyclopedidae, until recently, only one species was recognized, but new genetic studies have revealed that the group is represented by seven species. In this data-paper, we compiled a total of 42,528 records of 31 species, represented by occurrence and quantitative data, totaling 24,847 unique georeferenced records. The geographic range is from the south of the USA, Mexico, and Caribbean countries at the northern portion of the Neotropics, to its austral distribution in Argentina, Paraguay, Chile, and Uruguay. Regarding anteaters, Myrmecophaga tridactyla has the most records (n=5,941), and Cyclopes sp. has the fewest (n=240). The armadillo species with the most data is Dasypus novemcinctus (n=11,588), and the least recorded for Calyptophractus retusus (n=33). With regards to sloth species, Bradypus variegatus has the most records (n=962), and Bradypus pygmaeus has the fewest (n=12). Our main objective with Neotropical Xenarthrans is to make occurrence and quantitative data available to facilitate more ecological research, particularly if we integrate the xenarthran data with other datasets of Neotropical Series which will become available very soon (i.e. Neotropical Carnivores, Neotropical Invasive Mammals, and Neotropical Hunters and Dogs). Therefore, studies on trophic cascades, hunting pressure, habitat loss, fragmentation effects, species invasion, and climate change effects will be possible with the Neotropical Xenarthrans dataset