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1. Sublinear drag regime at mesoscopic scales in viscoelastic materials

Author

Ferreira, A. E. O., de Araújo, J. L. B., Ferreira, W. P., de Sousa, J. S., and Oliveira, C. L. N.

Subjects
Soft Condensed Matter (cond-mat.soft), FOS: Physical sciences, Condensed Matter - Soft Condensed Matter
Abstract

Stressed soft materials commonly present viscoelastic signatures in the form of power-law or exponential decay. Understanding the origins of such rheologic behaviors is crucial to find proper technological applications. Using an elastic network model of macromolecules immersed in a viscous fluid, we numerically reproduce those characteristic viscoelastic relaxations and show how the microscopic interactions determine the rheologic response. We find that exponential relaxations are indeed the most common behavior. However, power laws may arise when drag forces between the macromolecules and the fluid are sublinear, which is related to micro-deformations of the macromolecules.

Published
2023
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2. Metallic Hydrogen: Experiments on Metastability

Author

Ferreira, W., Moller, M., Linsuain, K., Song, J., Salamat, A., Dias, R., and Silvera, I. F.

Subjects
Condensed Matter - Materials Science, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences
Abstract

Molecular hydrogen was pressurized in a diamond anvil cell at temperatures between 5 and 83 K. At a sufficiently high pressure, estimated to be between 477 to 491 GPa, hydrogen became metallic, determined by its reflectance in the near infrared and fit to a Drude free-electron model. We then studied the predicted metastability of metallic hydrogen. At a temperature of 5 K the load on the metallic hydrogen was stepwise reduced until the pressure was zero. While turning the load or pressure down, the sample evidently transformed to the molecular phase and escaped; the sample hole closed. We estimate this pressure to be 113 to 84 GPa. Metallic hydrogen was not observed to be metastable at zero pressure., Comment: 8 pages, 4 figures plus SI

Published
2022
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3. Educação em Foco: Teoria e Prática

Author

João Paulo de Sousa Pio, Priscila Rodrigues Boas, Eduardo Manuel Bartalini Gallego, Helves Belmiro da Silveira, Maria Santana Alves, Maria do Socorro Cordeiro de Sousa, Andreza Cordeiro Dranka, Gilton Sampaio de Souza, Maria José Santana Silva, Mary Lange Sousa Silva, Tainã Figueiredo Cardoso, Viviane Andrade Pinheiro, Késia Kelly Vieira de Castro, Klécio de Assis Raimundo, Wilderson Alves Leite, José Leonardo Ferreira Gomes, Hianne Maravilha Dantas e Sousa Almeida, Mércia Karine da Silva, Regina Dáucia de Oliveira Braga, Caroline Izidoro dos Santos, Leociléa Aparecida Vieira, Fabrícia Gomes da Silva Diniz, Nayana Shirado, Marília Cavalcanti de Freitas Moreira, Rodrigo Lacerda Carvalho, Divina Lucia Rodrigues Barbacena Monteiro, Jorcelita Bento dos Reis Gonçalves, Hélida Maravilha Dantas e Sousa Almeida, Rosana de Vasconcelos Sousa, Jairomar de Araújo Sobrinho, Marize Marques de Freitas, Ana Coelho, Ailton Batista de Albuquerque Junior, Elizabeth de Fátima Freitas Marcelino, Maria Rosilda Vasconcelos Sousa, Josiane da Trindade Damasceno, Aida Figueiredo, Ederson Gusella Oliveira, Rosângela Maria do Nascimento Lemos, Lucas Novais Barros, Raimundo Nonato de Menezes Moreira, Lidiane Rodrigues Campêlo da Silva, Manassés dos Santos Silva, Angela Maria Visgueira Cunha, Francione Charapa Alves, Sonia Maria Chaves Haracemiv, José Renato Sousa Rodrigues, Amsranon Guilherme Felicio Gomes Silva, José Fábio Vieira de Oliveira, Virna Freitas Benévolo, Samantha Joyce Ferreira W. da Silva, Leândra Maria de Souza, Ramon Roseno Alves, Cristiane de Souza, Cassandra Ribeiro Joye, Emerson Augusto de Medeiros, Leonardo Baptista, Elielma Carneiro Coutinho, Eduarda Medran Rangel, Raquel Ramos, Gilmar Ribeiro de Lima, Eugênia Muniz Agra, Daiana Kaster Garcez, Vera do Vale, Roseneide Maria Batista Cirino, Ana Melo Trindade, Beatriz Alves Leite, Rayna de Melo Carvalho, Estela Fernandes e Silva, Isabela Nogueira Nascimento, Cícero Helton Pereira, and Marília Maia Moreira

Published
2021
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4. Estudo de Desempenho e Critérios de Abordagem para Lajes Lisas Parcialmente Protendidas com Armaduras Ativas Não Aderentes

Author

FERREIRA, W. B., LUCHI, L. A. R. E., ARAUJO, E. R., and W.G. Ferreira

Subjects
monocordoalhas, lajes lisas protendidas, Concreto protendido
Abstract

Made available in DSpace on 2016-08-29T15:10:15Z (GMT). No. of bitstreams: 1 tese_8276_Wagner Badke Ferreira.pdf: 6488524 bytes, checksum: cbdf486ef204003655ef7cc95653ef43 (MD5) Previous issue date: 2013-11-29 Este trabalho apresenta um conceito refinado de abordagem de lajes lisas parcialmente protendidas com monocordoalhas pós-tracionadas, o trabalho se desenvolve passando por métodos de análises que englobam soluções para o tratamento da fluência, da punção, da distribuição de cabos em planta, além do comportamento global da estrutura e local da laje, por meio de um processo iterativo e de analise refinada, alinhado com os conceitos recomendados pela Norma Brasileira NBR 6118:2003, além de discussões sobre alguns pontos que poderiam ser mais flexíveis, como o espaçamento dos cabos em planta. Tomando como premissa um estudo mais acurado, que visa reproduzir na prática o modelo idealizado, tanto no aspecto teórico como experimental.

Published
2013

5. Strong magneto-elastic coupling and polar properties in orthorhombic Eu1-xYxMnO3 manganite

Author

Moreira, J. Agostinho, Almeida, A., Ferreira, W. S., Araújo, J. P., Pereira, A. M., Chaves, M. R., Costa, M. M. R., Khomchenko, V. A., Kreisel, J., Chernyshov, D., and Tavares, S. M. F. Vilela And P. B.

Subjects
Condensed Matter - Strongly Correlated Electrons, Strongly Correlated Electrons (cond-mat.str-el), FOS: Physical sciences
Abstract

This work reports an experimental investigation of the magneto-elastic coupling and polarization character of magnetic phases of the orthorhombic Eu1-xYxMnO3 system at low temperatures. The temperature dependence of the polarization reversal curves clearly reveals the existence of a reentrant improper ferroelectric phase for x = 0.2 and 0.3. Although a ferroelectric phase is also stable for x = 0.4, we have no experimental evidence that it vanishing at finite temperatures. From these results and those obtained from other experimental techniques, the corresponding (x,T) phase diagram was traced, yet yielding significant differences with regard to previous reports. An expressive magneto-elastic coupling is revealed by changes observed in both Mn-O bond lengths and Mn-O1-Mn bond angle at the magnetic phase transitions, obtained by temperature dependence of synchrotron x-ray diffraction experiments. Furthermore, signatures of the lattice deformations across the magnetic phase transitions were evidenced by anomalies in the temperature dependence of the lattice mode involving rotations of the MnO6 octahedra. These anomalies confirm the important role of the spin-phonon coupling in these materials., Comment: 12 Figures, 2 Tables

Published
2010
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6. Coupling between phonons and magnetic excitations in orthorhombic Eu_{1-x}Y_xMnO_3

Author

Moreira, J. Agostinho, Almeida, A., Ferreira, W. S., Chaves, M. R., Kreisel, J., Vilela, S. M. F., and Tavares, P. B.

Subjects
Condensed Matter - Other Condensed Matter, Condensed Matter - Materials Science, Condensed Matter::Materials Science, Condensed Matter::Superconductivity, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, Condensed Matter::Strongly Correlated Electrons, Other Condensed Matter (cond-mat.other)
Abstract

In this work we present a detailed study of the structural and lattice dynamic properties of Y-doped EuMnO3 ceramics (Eu1-xYxMnO3, with 0, Comment: 34 pages, 13 figures, 1 table, submitted to Phys. Rev. B

Published
2009
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7. Structure and correlations in two-dimensional Coulomb confined classical artificial atoms

Author

Ferreira, W. P., Matulis, A., Farias, G. A., and Peeters, F. M.

Subjects
Condensed Matter - Strongly Correlated Electrons, Strongly Correlated Electrons (cond-mat.str-el), FOS: Physical sciences
Abstract

The ordering of N equally charged particles (-e) moving in two dimensions and confined by a Coulomb potential, resulting from a displaced positive charge Ze is discussed. This is a classical model system for atoms. We obtain the configurations of the charged particles which, depending on the value of N and Z, may result in ring structures, hexagonal-type configurations and for N/Z~1 in an inner structure of particles which is separated by an outer ring of particles. For N/Z<, 9 pages, 11 figures. Submitted to Phys. Rev. E. RevTeX4 format

Published
2002
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8. An electron microscope study of the regenerating nerve fibers

Author

Estable C, Acosta-Ferreira W, and Sotelo

Subjects
Microscopy, Histology, Chemistry, Electrons, macromolecular substances, Cell Biology, Anatomy, Regenerative process, Pathology and Forensic Medicine, law.invention, Guinea pig, Microscopy, Electron, Nerve Fibers, nervous system, law, Electron microscope
Abstract

Guinea pig sciatic nerves were severed in order to obtain a regenerative process of the nerve fibers. The animals were killed at different periods of time after the severing (24 hours, 6 days and 12 days) and the specimens obtained were prepared for electronmicroscopic study.

Published
1957

21. HIV-2 seroprevalence in Guinea-Bissau

Author

João Piedade, Miguel Viveiros, Costa, C., Santos Pinto, A., Prieto, E., Albuquerque, R., Paulo Silva, A., Dias, F., Mansinho, K., Champalimaud, J., Araújo, C., and Canas Ferreira, W. F.

22. Geodiversity and biodiversity: An integrated analysis as a basis for the sustainable exploitation of the mineral resources of the Albardão Continental Shelf, Pelotas Sedimentary Basin, RS, Brazil,Geodiversidade e biodiversidade: Análise integrada como subsídio à explotação sustentável dos recursos minerais da Plataforma Continental do Albardão, Bacia Sedimentar de Pelotas, RS, Brasil

Author

Mattos, P. H., Tagliani, C. R. A., Pinotti, R. M., Joao Luiz Nicolodi, Calliari, L. J., Gandra, T. B. R., and Ferreira, W. L. S.

25. Antilonomic effects of Brazilian brown seaweed extracts

Author

Domingos, T. F. S., Carvalho, C., Moura, L. D. A., Valeria Laneuville Teixeira, Pereira, R. C., Bianco, É M., Ferreira, W. J., Ramos, C. J. B., Miranda, A. L. P., Melo, P. A., Guimarães, J. A., and Fuly, A. L.

32. Rapid Ecological Assessment of benthic indicators of water quality: A successful capacity-building experience for Brazilian postgraduate students in ecology | Avaliação ecológica rápida de indicadores bentônicos de qualidade de água: Uma experiência de sucesso na formação de pós-graduandos em ecologia no brasil

Author

Callisto, M., Adauto Ribeiro, Santana, V. B., França, J. S., Ligeiro, R., Ferreira, W. R., Silva, D., Castro, D., Tupinambás, T. H., Santana, D., Souza, B., Gonçalves, F., Rodrigues, L., Andrade, C. B., Sales, S. C. M., and Souza, R.

40. Development of a method for evaluating raw materials for use in iron ore sinter in terms of lime assimilation

Author

Ferreira, W., Robert Cromarty, and Villiers, J.

Subjects
sintering, lime assimilation, properties, iron ore
Abstract

Steel is produced in a basic oxygen furnace from hot metal obtained from a blast furnace. A sintered iron ore with good high-temperature properties (strength and permeability) should be used as feed to the blast furnace. The quality of this sintered ore depends on the reactivity of the iron ore used as feed to the sinter plant during the lime assimilation step in the sintering process. The penetration test is the standard method for evaluating the reactivity of iron ore with lime. It is, however, difficult to determine the exact depth of penetration from the standard test. A new test method is proposed that allows automatic evaluation of iron ores in terms of lime assimilation with increasing temperature. A comparison of the coefficients of variation for the new and standard methods for each ore type demonstrates that the results of the new test are more reproducible and more precise than those of the standard method. The test is also less time-consuming and easier to implement.

41. Molecular epidemiology of HIV

Author

Ricardo Parreira, Aida Esteves, Venenno, T., Franco, M., João Piedade, Sousa, J., and Canas-Ferreira, W. F.

50. Micellar antibiotics of bacillus

Author

Wilfried J. J. Meijer, William T. Ferreira, Karolina Bakun, Mateusz Hess, Sisareuth Tan, Loredana Baccigalupi, Simon M. Cutting, Mikhail Soloviev, James R. G. Adams, Ezio Ricca, Enrico Ferrari, Alain Brisson, María Teresa Rejas, Huynh A. Hong, Hannah Wood, Medical Research Council (UK), Ministerio de Economía y Competitividad (España), Ferreira, W. T., Hong, H. A., Hess, M., Adams, J. R. G., Wood, H., Bakun, K., Tan, S., Baccigalupi, L., Ferrari, E., Brisson, A., Ricca, E., Rejas, M. T., Meijer, W. J. J., Soloviev, M., and Cutting, S. M.

Subjects
medicine.drug_class, Antibiotics, Pharmaceutical Science, Bacillus, Bacillus subtilis, Bacillus velezensi, Micelle, Article, Microbiology, chemistry.chemical_compound, Pharmacy and materia medica, Chlorotetaine, Bacillus velezensis, medicine, biology, Chemistry, Lipopeptide, Biosurfactant, Antimicrobial, biology.organism_classification, C510 Applied Microbiology, RS1-441, Drug delivery, Bacteria
Abstract

Members of the Bacillus genus, particularly the “Bacillus subtilis group”, are known to produce amphipathic lipopeptides with biosurfactant activity. This includes the surfactins, fengycins and iturins that have been associated with antibacterial, antifungal, and anti-viral properties. We have screened a large collection of Bacillus, isolated from human, animal, estuarine water and soil samples and found that the most potent lipopeptide producers are members of the species Bacillus velezensis. B. velezensis lipopeptides exhibited anti-bacterial activity which was localised on the surface of both vegetative cells and spores. Interestingly, lipopeptide micelles (6–10 nm diameter) were detectable in strains exhibiting the highest levels of activity. Micelles were stable (heat and gastric stable) and shown to entrap other antimicrobials produced by the host bacterium (exampled here was the dipeptide antibiotic chlorotetaine). Commercially acquired lipopeptides did not exhibit similar levels of inhibitory activity and we suspect that micelle formation may relate to the particular isomeric forms produced by individual bacteria. Using naturally produced micelle formulations we demonstrated that they could entrap antimicrobial compounds (e.g., clindamycin, vancomycin and resveratrol). Micellar incorporation of antibiotics increased activity. Bacillus is a prolific producer of antimicrobials, and this phenomenon could be exploited naturally to augment antimicrobial activity. From an applied perspective, the ability to readily produce Bacillus micelles and formulate with drugs enables a possible strategy for enhanced drug delivery., Medical Research Council (MR/R026262/1) to SMCand the Ministry of Economy and Competitiveness of the Spanish Government PID2019_108778GB_C21 (AEI/FEDER, EU)

Published
2021

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