An indirect numerical method for a time-optimal state-constrained control problem in a steady two-dimensional fluid flow

This article concerns the problem of computing solutions to state-constrained optimal control problems whose trajectory is affected by a flow field. This general mathematical framework is particularly pertinent to the requirements underlying the control of Autonomous Underwater Vehicles in realistic scenarii. The key contribution consists in devising a computational indirect method which becomes effective in the numerical computation of extremals to optimal control problems with state constraints by using the maximum principle in Gamkrelidze's form in which the measure Lagrange multiplier is ensured to be continuous. The specific problem of time-optimal control of an Autonomous Underwater Vehicle in a bounded space set, subject to the effect of a flow field and with bounded actuation, is used to illustrate the proposed approach. The corresponding numerical results are presented and discussed

Regular path-constrained time-optimal control problems in three-dimensional flow fields

This article concerns a class of time-optimal state constrained control problems with dynamics defined by an ordinary differential equation involving a three-dimensional steady flow vector field. The problem is solved via an indirect method based on the maximum principle in Gamkrelidze's form. The proposed computational method essentially uses a certain regularity condition imposed on the data of the problem. The property of regularity guarantees the continuity of the measure multiplier associated with the state constraint, and ensures the appropriate behavior of the corresponding numerical procedure which, in general, consists in computing the entire field of extremals for the problem in question. Several examples of vector fields are considered to illustrate the computational approach.Comment: 23 page

Síntese e caraterização de fotoanodos nanoestruturados para aplicação em células fotoeletroquímicas

Anais do VI Encontro de Iniciação Científica e II Encontro Anual de Iniciação ao Desenvolvimento Tecnológico e Inovação – EICTI 2017 - 04 a 06 de outubro de 2017 - temática Coências Exatas e da TerraO presente trabalho surge num contexto de crescente demanda energética, na busca de soluções eficientes que permitam diminuir a dependência de combustíveis fósseis através do avanço das tecnologias associadas as fontes renováveis de energia, especificamente a energia solar. Em termos de mercado as principais células solares são feitas a base de silício, porem, novas tecnologias que buscam um aumento da eficiência associado a custos mais baixos de produção estão ganhando visibilidade, e dentre elas, encontram-se as células solares sensibilizadas com corante (CSSC). Embora estas células sejam estudadas desde os anos 70 (Tributsch,1972), só ganharam maior atenção quando O ́Regan & Grätzel (1991) conseguiram um aumento significativo na eficiência de conversão de energia nas CSSC desenvolvidas a partir de óxido de titânio (TiO 2 ), passando de 2,5 para 7,1% na eficiência de conversão de energia. Atualmente este tipo de células já alcançaram um máximo de eficiência de 14% (Kakiage et al., 2015)Universidade Federal da Integração Latino-Americana (Unila); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Fundação Araucária; Parque Tecnológico Itaipu (PTI) e Companhia de Saneamento do Paraná (SANEPAR

Síntese e caracterização de fotoanodos nanoestruturados de TIO2 e ZNO para aplicação em células fotoeletroquímicas

Anais do V Encontro de Iniciação Científica e I Encontro Anual de Iniciação ao Desenvolvimento Tecnológico e Inovação – EICTI 2016 - 05 e 07 de outubro de 2016 – Sessão Ciências Exatas e da TerraO presente trabalho surge num contexto de crescente demanda energética, na busca de soluções eficientes que permitam diminuir a dependência de combustíveis fósseis por meio do avanço das tecnologias associadas as fontes renováveis de energia. Este trabalho visa contribuir na área de pesquisa em materiais semicondutores desenvolvidos para aplicação em células fotoeletroquímicas mediante o entendimento de mecanismos cinéticos e termodinâmicos dos dispositivos que compõem esses dispositivos de conversão de energia

Ferric citrate and ferric EDTA but not ferrous sulfate drive amphiregulin-mediated activation of the MAP kinase ERK in gut epithelial cancer cells.

Ferric chelates may be used as oral iron supplements or phosphate binders but both ferric citrate and ferric EDTA have been shown to promote tumor burden in murine models of colon cancer. Here we studied their effects on cancer cell growth, at typical supplemental iron levels encountered in the gastrointestinal tract (0.01-0.2 mM). Caco-2 and/or Hutu-80 cells were exposed to these forms of chelated iron or to ferrous sulfate and outcomes were assessed using cell proliferation assays, proteome profiler arrays, western blot, and ELISA. Ferric EDTA and ferric citrate increased cellular levels of the onco-protein amphiregulin and its receptor (EGFr) which in turn stimulated the activation of the MAP kinase ERK. Simultaneously, the expression of the negative Wnt regulator, DKK-1, increased suggesting that cell proliferation through the Wnt pathway may be less pronounced in the presence of ferric EDTA and ferric citrate, unlike for ferrous sulfate. Moreover, ferrous sulfate did not increase levels of cellular amphiregulin or EGFr. We conclude that specific iron compounds affect cell signaling differently and some may increase the risk of colon cancer advancement in an amphiregulin-dependent fashion. Further scrutiny of safe oral iron use is merited

Suplementação nutricional de creatina e saúde gastrintestinal: um estudo de revisão

Nos últimos anos, os pesquisadores têm investigado o potencial papel terapêutico da suplementação de creatina como adjuvante no tratamento ou na prevenção de doenças. Tem sido sugerido que a suplementação de creatina pode ser valiosa em doenças inflamatórias intestinais devido à sua capacidade postulada de modular a resposta imune e reduzir a dor induzida por inflamação. O trabalho foi realizado objetivando a análise da suplementação com creatina aprovada na literatura científica e que pode ser utilizada visando melhoria na inflamação e doenças inflamatórias intestinais. Uma pesquisa nos sites Tripdatabase, Google Schol, LILACS, Pubmed e Scielo foi conduzida para identificar artigos relevantes sobre a o uso terapêutico da suplementação nutricional da creatina, avaliando os possíveis benefícios por indivíduos, em doenças gastrintestinais. A suplementação com monohidrato de creatina demonstrou ser segura e muito eficiente para saúde gastrintestinal, tendo em vista a creatina pode diminuir os marcadores de inflamação e reduzir à sensibilidade à dor, associada à inflamação, modulando a formação de barreira epitelial do intestino

How Bulk Sensitive is Hard X-ray Photoelectron Spectroscopy: Accounting for the Cathode-Electrolyte Interface when Addressing Oxygen Redox.

Sensitivity to the "bulk" oxygen core orbital makes hard X-ray photoelectron spectroscopy (HAXPES) an appealing technique for studying oxygen redox candidates. Various studies have reported an additional O 1s peak (530-531 eV) at high voltages, which has been considered a direct signature of the bulk oxygen redox process. Here, we find the emergence of a 530.4 eV O 1s HAXPES peak for three model cathodes-Li2MnO3, Li-rich NMC, and NMC 442-that shows no clear link to oxygen redox. Instead, the 530.4 eV peak for these three systems is attributed to transition metal reduction and electrolyte decomposition in the near-surface region. Claims of oxygen redox relying on photoelectron spectroscopy must explicitly account for the surface sensitivity of this technique and the extent of the cathode degradation layer

Modification of the mycobacteriophage Ms6 attP core allows the integration of multiple vectors into different tRNA(ala )T-loops in slow- and fast-growing mycobacteria

BACKGROUND: Mycobacteriophage Ms6 integrates into Mycobacterium smegmatis and M. bovis BCG chromosome at the 3' end of tRNA(ala )genes. Homologous recombination occurs between the phage attP core and the attB site located in the T-loop. Integration-proficient vectors derived from Ms6 are useful genetic tools, but their insertion sites in the BCG chromosome remain poorly defined. The primary objective of this study was to identify Ms6 target genes in M. smegmatis and BCG. We then aimed to modify the attP site in Ms6-derived vectors, to switch integration to other tRNA(ala )loci. This provided the basis for the development of recombinant M. bovis BCG strains expressing several reporter genes inserted into different tRNA(ala )genes. RESULTS: The three tRNA(ala )genes are highly conserved in M. smegmatis and BCG. However, in the T-loop of tRNA(alaU )and tRNA(alaV )containing the attB site, a single base difference was observed between the two species. We observed that the tRNA(alaU )gene was the only site into which Ms6-derived integration-proficient vectors integrated in M. smegmatis, whereas in BCG, the tRNA(alaV )gene was used as the target. No integration occurred in the BCG tRNA(alaU )T-loop, despite a difference of only one base from the 26-base Ms6 attP core. We mutated the attP core to give a perfect match with the other tRNA(ala )T-loops from M. smegmatis and BCG. Modification of the seven-base T-loop decreased integration efficiency, identifying this site as a possible site of strand exchange. Finally, two Ms6 vectors were constructed to integrate two reporter genes into the tRNA(alaU )and tRNA(alaV )T-loops of the same BCG chromosome. CONCLUSION: Small changes in the 7 bp T-loop attP site of Ms6 made it possible to use another attB site, albeit with a lower integration efficiency. These molecular studies on BCG tRNA(ala )genes made it possible to create valuable tools for the site-directed insertion of several genes in the same BCG strain. These tools will be useful for the development of novel multivalent vaccines and genetic studies

Antibacterial Effect of Silver Nanoparticles on Klebsiella spp

Silver nanoparticles (AgNP) can be incorporated into medical devices, such as tissues, to circumvent bacterial resistance such as Klebsiella spp, which can lead to skin and mucosal infections. Thus, the aim of the present study was to synthesize silver nanoparticles for later incorporation into cotton fabrics and in vitro tests against Klebsiella spp. The AgNP colloidal solution was synthesized (AgNO3 - 0.1 mM, 100 mM trisodium citrate, polyvinylpyrrolidone - 0.24 g, H2OH2) and then impregnated into the cotton fabric pretreated with poly diallyl dimethylammonium chloride (PDDA) of 100/500 tissue, shaken for 30 minutes). The material produced was analyzed by the FTIR; DLS and reflectance spectroscopy. The tests of the antimicrobial activities were by the microdilution technique against Klebsiella spp, in tubes containing Brain Heart Infusion (BHI), with the solution of silver (1); Tissue containing AgNP - 4 mm (2); Negative control (3) and positive control - ceftriaxone (4). Regarding MIC, the inhibitory activity occurred of the dilutions between 1/2 and 1/16. The AgNP particles had an average size of 24.75 nm. As synthesized AgNPs demonstrate the excellent antimicrobial activity against Klebsiella spp, with special emphasis on applications in nanotechnology and nanomedicine, targeting multiresistant antibiotic bacteria