The carreau-yasuda fluids: a skin friction equation for turbulent flow in pipes and kolmogorov dissipative scales

In this work the turbulent flow of the Non-Newtonian Carreau-Yasuda fluid will be studied. A skin friction equation for the turbulent flow of Carreau-Yasuda fluids will be derived assuming a logarithmic behavior of the turbulent mean velocity for the near wall flow out of the viscous sub layer. An alternative near wall characteristic length scale which takes into account the effects of the relaxation time will be introduced. The characteristic length will be obtained through the analysis of viscous region near the wall. The results compared with experimental data obtained with Tylose (methyl hydroxil cellulose) solutions showing good agreement. The relations between scales integral and dissipative obtained for length, time, velocity, kinetic energy, and vorticity will be derived for this type of fluid. When the power law index approach to unity the relations reduces to Newtonian case.

Uranium-lead dating method at the Pará-Iso isotope geology laboratory, UFPA, Belém – Brazil

ABSTRACT: Analytical procedures for U-Pb isotope dilution analyses at the Pará-Iso isotope geology laboratory of the Federal University of Pará (UFPA) are described in detail. The procedures are applied to zircon, titanite, rutile, apatite, columbite-tantalite and whole rock. Reagent preparation and chemical processing are done in clean-room conditions. Samples are dissolved using Teflon™ microcapsules in steel jacket Teflon™ Parr Instrument™ bomb or Teflon™ screw cap containers. U and Pb are separated using anion exchange AG 1x8 resin columns. Typical blanks for mineral sample amounts of 0.01 to 1.0 mg are less than 1 pg U and 20-30 pg Pb. Isotope analysis of the U and Pb from the same filament are carried out using a Finnigan MAT 262 mass-spectrometer in static and dynamic modes. The current analytical level is demonstrated on analyses of international standard zircon 91500 with three different ²³⁵U-²⁰⁵Pb and ²³⁵U-²⁰⁸Pb isotope tracers and whole rock standards. Results of analyses of two zircon samples are also presented.

Lead poisoning in cattle and chickens in the state of Pará, Brazil

O presente estudo descreve a ocorrência de intoxicação por chumbo em bovinos e galinhas no Pará, Brasil. Em um lote composto de 80 bezerros de um rebanho leiteiro, 10 animais ficaram doentes e nove morreram, e um animal se recuperou após ser removido do piquete. Após a inspeção deste piquete, foi observada a presença de baterias de caminhões usados para armazenar a energia captada por painéis solares. Os sinais clínicos observados nos bezerros incluíam dificuldade respiratória, corrimento nasal, salivação excessiva, opacidade da córnea, pressão da cabeça contra objetos e decúbito. As galinhas tinham diminuída oviposição e os ovos produzidos eram com cascas malformadas ou tinham a casca mais fina. Os achados de necropsia e as alterações histopatológicas observadas nos bovinos eram de pouco significado, com exceção de um animal que mostrou leve astrocitose no córtex cerebral. Em uma das galinhas, na histopatologia renal observou-se leve necrose tubular aguda multifocal. As concentrações de chumbo médios nos fígados e rins dos bovinos eram 93,91mg/kg e 209,76mg/kg, respectivamente, e a concentração média no fígado de galinhas foi 105,02mg/ kg. Concluiu-se que a fonte de contaminação por chumbo nesses bezerros e galinhas eram placas de bateria de caminhão, aos quais os animais tiveram acesso na pastagem.