534 research outputs found
Wax Chemical and Morphological Investigation of Brazilian Crude Oils
The waxes in petroleum can precipitate and form unwanted gels and deposition when exposed to low temperatures. The idea of this chapter is to approach methods of quantification and physicochemical and morphological characterization of waxes and how this information can help in understanding this deposition. Information such as the quantity of waxes and the chemical structures in the oil is fundamental to predict the possible deposition and its ability to aggregate with other crystals. For example, the knowledge about the wax morphology may contribute to explain the nucleation and growth of the deposits. The polarized light microscopy, the most common technique to visualize wax crystals, and the bright-field microscopy, the most simple technique, able to show crystal details that have not been seen on the polarized light, was used
Stress Concentration on PDMS: An evaluation of three numerical constitutive models using digital image correlation
The examination of hyperelastic materials’ behavior, such as polydimethylsiloxane (PDMS), is crucial for applications
in areas as biomedicine and electronics. However, the limitations of hyperelastic models for specific
stress scenarios, with stress concentration, are not well explored on the literature. To address this, firstly, three
constitutive models were evaluated (Neo-Hookean, Mooney-Rivlin, and Ogden) using numerical simulations and
Digital Image Correlation (DIC) analysis during a uniaxial tensile test. The samples were made of PDMS with
stress concentration geometries (center holes, shoulder fillets, and edge notches). Results of ANOVA analysis
showed that any of the three models can be chosen for numerical analysis of PDMS since no significant differences
in suitability were found. Finally, the Ogen model was chosen to obtain the stress concentration factors for
these geometries, a property which characterize how discontinuities change the maximum stress supported by an
element. Our study provides new values for variables needed to analyze and design hyperelastic elements and
produce a foundation for understanding PDMS stress-strain behavior.The authors acknowledge the projects EXPL/EME-EME/0732/2021
and 2022.06207.PTDC for the financial support, through national funds
(OE), within the scope of the Scientific Research and Technological
Development Projects (IC&DT) program in all scientific domains
(PTDC), PORTUGAL 2020 Partnership Agreement, European Regional
Development Fund (FEDER), via the Foundation for Science and Technology,
I.P. (FCT, I.P) and the R&D Units projects (UIDB/00690/2020
and UIDP/00690/2020) (CIMO), SusTEC (LA/P/0007/2020), UIDB/
04077/2020, UIDP/04077/2020, UIDB/04436/2020 and UIDB/00532/
2020. Andrews Souza acknowledges FCT for the Ph.D. scholarship
2021.07961.BD.info:eu-repo/semantics/publishedVersio
Cultivo de Calophyllum braziliense em várzea e terraço fluvial e seleção de espécies para a conversão agroflorestal.
O cultivo agroflorestal de Guanandi - Calophyllum braziliense nas várzeas e terraços fluviais do Vale do Paraíba é sustentável e representa baixo impacto ambiental na principal bacia hidrográfica da região Sudeste do Brasil. Este estudo de caso contém informações do Projeto desenvolvido na centenária Fazenda Coruputuba, em Pindamonhangaba, SP. Aborda aspectos ecofisiológicos do gênero Calophyllum que torna o guanandi apto ao cultivo sob inundação e contém uma seleção de espécies adaptadas aos dois ambientes: várzea inundável e terraço fluvial
Structural aspects of the fermion-boson mapping in two-dimensional gauge and anomalous gauge theories with massive fermions
Using a synthesis of the functional integral and operator approaches we
discuss the fermion-boson mapping and the role played by the Bose field algebra
in the Hilbert space of two-dimensional gauge and anomalous gauge field
theories with massive fermions. In the with quartic self-interaction
among massive fermions, the use of an auxiliary vector field introduces a
redundant Bose field algebra that should not be considered as an element of the
intrinsic algebraic structure defining the model. In the anomalous chiral
with massive fermions the effect of the chiral anomaly leads to the
appearance in the mass operator of a spurious Bose field combination. This
phase factor carries no fermion selection rule and the expected absence of
-vacuum in the anomalous model is displayed from the operator solution.
Even in the anomalous model with massive Fermi fields, the introduction of the
Wess-Zumino field replicates the theory, changing neither its algebraic content
nor its physical content.Comment: 26 pages, Revte
Oral treatment with Saccharomyces cerevisiae strain UFMG 905 modulates immune responses and interferes with signal pathways involved in the activation of inflammation in a murine model of typhoid fever
AbstractSalmonella spp. are Gram-negative, facultative, intracellular pathogens that cause several diarrheal diseases ranging from self-limiting gastroenteritis to typhoid fever. Previous results from our laboratory showed that Saccharomyces cerevisiae strain UFMG 905 isolated from ‘cachaça’ production presented probiotic properties due to its ability to protect against experimental infection with Salmonella enterica serovar Typhimurium. In this study, the effects of oral treatment with S. cerevisiae 905 were evaluated at the immunological level in a murine model of typhoid fever. Treatment with S. cerevisiae 905 inhibited weight loss and increased survival rate after Salmonella challenge. Immunological data demonstrated that S. cerevisiae 905 decreased levels of proinflammatory cytokines and modulated the activation of mitogen-activated protein kinases (p38 and JNK, but not ERK1/2), NF-κB and AP-1, signaling pathways which are involved in the transcriptional activation of proinflammatory mediators. Experiments in germ-free mice revealed that probiotic effects were due, at least in part, to the binding of Salmonella to the yeast. In conclusion, S. cerevisiae 905 acts as a potential new biotherapy against S. Typhimurium infection due to its ability to bind bacteria and modulate signaling pathways involved in the activation of inflammation in a murine model of typhoid fever
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