122 research outputs found

    Transformations of Heun's equation and its integral relations

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    We find transformations of variables which preserve the form of the equation for the kernels of integral relations among solutions of the Heun equation. These transformations lead to new kernels for the Heun equation, given by single hypergeometric functions (Lambe-Ward-type kernels) and by products of two hypergeometric functions (Erd\'elyi-type). Such kernels, by a limiting process, also afford new kernels for the confluent Heun equation.Comment: This version was published in J. Phys. A: Math. Theor. 44 (2011) 07520

    Development of β-TCP-Ti6Al4V structures: Driving cellular response by modulating physical and chemical properties

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    Acknowledgments This work was supported by FCT (Fundação para a Ciência e Tecnologia) through the grants SFRH/BD/140191/2018; SFRH/BPD/112111/2015, SFRH/BD/128657/2017, SFRH/BD/141056/2018; SFRH/BPD/97701/2013, PD/BDE/127836/2016, and the projects PTDC/EMS-TEC/5422/2014_ADAPTPROSTHESIS and NORTE-01- 0145-FEDER-000018-HAMaBICo. Additionally, this work was supported by FCT with the reference project UID/EEA/04436/2013, by FEDER funds through the COMPETE 2020 – Programa Operacional Competitividade e Internacionalização (POCI) with the reference project POCI-01-0145-FEDER-006941.Load-bearing implants success is strongly dependent on several physical and chemical properties that are known to drive cellular response. In this work, multi-material β-TCP-Ti6Al4V cellular structures were designed to combine Ti6Al4V mechanical properties and β-Tricalcium Phosphate bioactivity, in order to promote bone ingrowth as the bioactive material is being absorbed and replaced by newly formed bone. In this sense, the produced structures were characterized regarding roughness, wettability, β-TCP quantity and quality inside the structures after fabrication and the pH measured during cell culture (as consequence of β-TCP dissolution) and those aspects were correlated with cellular viability, distribution, morphology and proliferation. These structures displayed a hydrophilic behavior and results showed that the addition of β-TCP to these cellular structures led to an alkalization of the medium, aspect that significantly influences the cellular response. Higher impregnation ratios were found more adequate for lowering the media pH and toxicity, and thus enhance cell adhesion and proliferation.info:eu-repo/semantics/publishedVersio

    45S5 BAG-Ti6Al4V structures: The influence of the design on some of the physical and chemical interactions that drive cellular response

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    This work was supported by FCT (Fundação para a Ciência e Tecnologia) through the grants SFRH/BPD/112111/2015, SFRH/BD/128657/2017, PD/BDE/127836/2016, SFRH/BPD/97701/2013, SFRH/ BD/141056/2018, SFRH/BD/140191/2018 and the projects PTDC/EMSTEC/5422/2014 and NORTE-01-0145-FEDER-000018-HAMaBICo. Additionally, this work was supported by FCT with the reference project UID/EEA/04436/2013, by FEDER funds through the COMPETE 2020 – Programa Operacional Competitividade e Internacionalização (POCI) with the reference project POCI-01-0145-FEDER-006941.Multi-material Ti6Al4V cellular structures impregnated with 45S5 bioactive glass were designed and produced using Selective LaserMelting (SLM), an additive manufacturing technique, combinedwith Press and Sintering focusing on load bearing components like hip implants. These structures were designed to combine Ti6Al4V mechanical properties and promote bone ingrowth into the structure as the bioactive material (45S5) is being absorbed and replaced by newly formed bone. The influence of these structures design on some of the physical and chemical aspects that drive cellular response was assessed. Roughness, wettability, bioactive glass quantity and quality on the structures after processing and the pH measured during cell culture (as a consequence of bioactive glass dissolution) were evaluated and correlated with cellular viability, cellular distribution, morphology and proliferation on the surface and inside the structures.info:eu-repo/semantics/publishedVersio

    Rumo a um Observatório Latino-Americano do Clima e da Saúde: Seminário sobre Instrumentos e Metodologias

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    The study of the relationship between health and climate requires articulating various actors and disciplines. This paper presents the experience of the Latin American Seminar on Instruments and Methodologies for a climate and health observatory— held in Buenos Aires in 2019 and supported by the Latin American Center for Interdisciplinary Training (CELFI)—as a linking and training facility referencing the projects that are being carried out in this field throughout Latin American. This paper presents the design, contents, didactic approach and execution of the seminar, as well as its results regarding participation, products and evaluation. Likewise, the methodologies that could allow articulating different disciplines in a process of gainingknowledge about the climate-health relationship are reflected throughout this process. Finally, the main guidelines for this observatory, arising from an exchange with key actors, are set forth herein. The execution of the seminar, the projects presented as the products thereof, the discussions that arose during the exchange, and the need to continue with this work over the following months point out to the importance and necessity of building this observatory for Latin America and the Caribbean in an interdisciplinary way.El estudio de la relación entre clima y salud requiere la articulación de diversos actores y disciplinas. En este artículo se presenta la experiencia del Seminario Latinoamericano Instrumentos y Metodologías para un observatorio de clima y salud, realizado en Buenos Aires en 2019, apoyado por el Centro Latinoamericano de Formación Interdisciplinaria (CELFI), como un espacio de vinculación, capacitación y referencia a experiencias que se vienen desarrollando en este campo en América Latina. En este trabajo se presenta el diseño del seminario, su contenido, didáctica y desarrollo, así como los resultados en cuanto a participación, productos y evaluación. Asimismo, durante el proceso se reflexiona en torno a las metodologías que permitan articular diferentes disciplinas en un proceso de construcción de conocimiento sobre la relación clima-salud. Finalmente, se explicitan los principales lineamientos del observatorio, surgidos de una instancia de intercambio con actores clave. El desarrollo del seminario, los proyectos presentados como producto, las discusiones surgidas durante el intercambio y la continuidad de trabajo en los meses posteriores permiten dar cuenta de la importancia y necesidad de construir interdisciplinariamente este observatorio para América Latina y el Caribe.O estudo da relação entre o clima e a saúde requere a articulação de diversos atores e disciplinas. Neste artigo, apresenta-se a experiência do Seminário Latino-americano Instrumentos e Metodologias para um observatório de clima e saúde, realizado em Buenos Aires em 2019. Foi apoiado pelo Centro Latino-americano de Formação Interdisciplinar (CELFI), como espaço de vinculação, capacitação e referência das experiências que se estão a desenvolver neste campo na América Latina. Neste trabalho, apresenta- se a conceção do seminário, o seu conteúdo, dinâmica e desenvolvimento, bem como, os resultados em termos de participação, produtos e avaliação. Da mesma forma, durante o processo, é feita uma reflexão sobre as metodologias que permitem a articulação de diferentes disciplinas, num processo de construção do conhecimento sobre a relação clima-saúde. Por fim, explicitam-se as principais diretrizes do observatório, decorrentes de uma plataforma de intercâmbio dos atores chave. O desenvolvimento do seminário, os projetos apresentados como produto, as discussões ocorridas durante o intercâmbio e a continuidade de trabalho nos meses seguintes, permitem perceber a importância e a necessidade de construir este observatório interdisciplinar, para a América Latina e Caribe

    Photoinactivation of bacterial and fungal planktonic/biofilm forms using the combination of a porphyrinic formulation with potassium iodide

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    Antimicrobial photodynamic therapy (aPDT) is a promising approach against multidrug-resistant microorganisms. In this work, we accessed the photodynamic efficiency of an affordable formulation composed of five cationic porphyrins (FORM) and its combined effect with potassium iodide (KI) on a large spectrum of microorganisms. For this purpose, the aPDT assays were conducted with FORM alone and FORM + KI on planktonic and biofilm forms of Gram(+) (Staphylococcus aureus) and Gram(−) (Escherichia coli) bacteria and of the yeast Candida albicans. The results obtained indicate that FORM, at low concentrations (0.5–5.0 μM), had an efficient photodynamic action on the planktonic forms of E. coli, S. aureus, and C. albicans. Moreover, the combination of FORM with KI improved the photodynamic action of this PS, promoting microbial inactivation with lower PS concentrations and treatment time. The combination of FORM + KI was also extremely efficient in the destruction of bacterial and fungal biofilms. This outstanding effect may be due to the action of longer-lived iodine reactive species produced by the reaction of KI with the ROS generated by FORM during the aPDT treatment.info:eu-repo/semantics/publishedVersio

    Photodynamic inactivation of a RNA-virus model using water-soluble β-octa-Substituted pyridinium-pyrazolyl phthalocyanines

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    Among the various groups of microorganisms, viruses have generally a greater capacity for mutation, especially RNA viruses, as was demonstrated by SARS-CoV2 virus mutations. This high mutation rate promotes the development of their resistance to traditional antivirals and establishes the resistance behaviour in virus populations, decreasing their susceptibility to these drugs. In this context, the photodynamic treatment appears as a potentially effective method against microorganisms and, considering its mode of action is not likely to lead to the development of resistance. In this work, two newly zinc(II) phthalocyanines (ZnPcs) bearing pyridinium-pyrazolyl groups (2a and 3a) were synthesized, characterized, and applied in photodynamic inactivation (PDI) of bacteriophage Φ6 (or Phage Phi6) as a RNA-virus model. These quaternized dyes were applied at different concentrations (from 5.0 to 20 μM, and under white light irradiation in the irradiance range between 50 and 150 mW/cm2) to test their efficiency for possible clinical or environmental applications. The results showed that the new cationic ZnPcs 2a and 3a efficiently inactivate the RNA-virus model (bacteriophage Φ6), even at the lowest tested irradiance. These compounds are thus promising photosensitizers to be used in various contexts.info:eu-repo/semantics/publishedVersio

    Caracterização de sementes de pinhão (Araucaria angustifolia) de diferentes procedências, do Estado do Paraná.

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    This study aimed to perform the characterization of raw pine nuts from Curitiba and Guarapuava, cities of Paraná State. The pine nuts showed peculiar characteristics, being influenced by genetic inheritance and or environmental conditions of different cities. The main differences found between samples were in relation to starch content 45,16 ± 1,38 and 57,26 ± 3,15 (g/100g); average mass of seeds 5,35 ± 0,79 and 7,91 ± 0,57(g); and external hardness of almond 13,87 ± 0,57 and 24,11 ± 3,49, respectively for samples from Curitiba and Guarapuava. The pine nuts show as a good source of starch, with pH near to neutrality and a high activity of water so these factors may compromise your stability. Therefore, the regions of sample collection influence the characteristics of pine nuts

    Crescimento e desenvolvimento do Pinhão manso: 1º ano agrícola.

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    bitstream/CNPA-2009-09/22147/1/DOC197.pd

    Tribological behavior of 316L stainless steel reinforced with CuCoBe + diamond composites by laser sintering and hot pressing: a comparative statistical study

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    The aim of this work was to perform a statistical analysis in order to assess how the tribological properties of a laser textured 316L stainless steel reinforced with CuCoBe - diamond composites are affected by diamond particles size, type of technology (laser sintering and hot pressing) and time of tribological test. The analysis started with the description of all response variables. Then, by using IBM® SPSS software, the Friedman’s test was used to compare how the coefficient of friction varied among samples in five-time points. From this test, results showed that there was no statistically significant difference in the coefficient of friction mean values over the selected time points. Then, the two-samples Kolmogorov-Smirnov (K-S) test was used to test the effect of the diamond particles size and the type of technology on the mean of the coefficient of friction over time. The results showed that, for both sintering techniques, the size of the diamond particles significantly affected the values of the coefficient of friction, whereas no statistical differences were found between the tested sintering techniques. Also, the two-way ANOVA test was used to evaluate how these factors influence the specific wear rate, which conducted to the same conclusions drawn for the previous test. The main conclusion was that the coefficient of friction and the specific wear rate were statistically affected by the diamond particles size, but not by the sintering techniques used in this work.This work was supported by FCT national funds, under the national support to R&D units grant, through the reference projects UIDB/04436/2020 and UIDP/04436/2020. Additionally, this work was supported by FCT with the reference projects UIDB/00319/2020 and PTDC/CTM-COM/30416/2017
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