Resonant couplings in U-shaped fibers for biosensing Londero, Carolina; Delgado-Pinar, Martina; Cuadrado-Laborde, Christian ...
Journal of lightwave technology,
07/2023, Letnik:
41, Številka:
13
Journal Article
Recenzirano
Odprti dostop
U-shaped tight curvatures in optical fibers lead to resonant couplings between the fundamental and higher order modes that are sensible to different parameters, such as strain or temperature, for ...example. The optical response of the sensor consists on the shift of the resonant wavelength of the coupling. In the case of singlemode fibers, the coupling involves a so-called "cladding mode" and, due to its evanescent field, the curved region will be sensible to changes in the external medium, as well. In this paper, we present the fabrication and characterization of a robust, easy-to-make, U-shaped fiber sensor based on singlemode telecom fiber and its application for biosensing. The resonant nature of the sensing mechanism presents the advantage of large dynamic ranges for RI variations without the ambiguity of other techniques such as interferometry. We studied the performance of the U-shaped fiber sensor for different bending radii, to optimize its sensitivity and detection limit at 1550 nm operation wavelength, as well as the effect of temperature on its response. The shift of the resonant wavelength was measured in detail as a function of the external RI within the range 1.33-1,37; the detection limit was established in (3.71±0.03)×10 -5 RIU. Furthermore, the device was successfully tested as a proof of concept biosensor, using a system model antigen-antibody (BSA-aBSA.)
The simultaneous determination of adhesion and deformability parameters of erythrocytes was carried out through a microfluidic device, which uses an inverted optical microscope with new image ...acquisition and analysis technologies. Also, an update of the models describing erythrocyte adhesion and deformation was proposed. Measurements were carried out with red blood cells suspended in saline solution with human serum albumin at different concentrations. Erythrocytes adhered to a glass surface were subjected to different low shear stress (from 0.04 to 0.25 Pa), causing cellular deformation and dissociation. The maximum value obtained of the erythrocyte deformability index was 0.3, and that of the adhesion energy per unit area was 1.1 × 10
−6
Pa m, both according to previous works. The obtained images of RBCs adhered to glass reveal that the adhesion is stronger in a single point of the cell, suggesting a ligand migration that concentrates the adhesion in a “spike-like tip” in the cell. Moreover, adhesion energy results indicate that the energy required to separate erythrocytes in media with a lower albumin concentration is greater. Both results could be explained by the mobility of membrane receptors.
The cement production is responsible for about 7% of global emissions of carbon dioxide (CO2) into the atmosphere. One way to mitigate this impact is through the consolidation of techniques involving ...the production of environmentally sustainable mixtures, such as partially replacing cement for mineral admixtures. This paper aims to use a mix-design method based on particle packing techniques to produce and evaluate the properties of a low-cement concrete (LCC). This mix-design method is based on cyclic interactions, where the particle packing, the water demand and a prediction of the concrete compressive strength is performed. Granular optimization studies of the aggregates and the fine materials, rice husk ash and quartz powder, were carried out to reduce the number of voids in the concrete and partially replace Portland cement. A concrete designed by a conventional mix-design method was taken as a starting point for the application of the particle packing techniques, in the quest to reduce cement consumption, so that it was called initial concrete (C0). Concrete properties evaluated, in the fresh state, were consistency through slump test and specific gravity. In the hardened state, properties of compressive strength, tensile strength by diametrical compression, specific gravity and water absorption tests by immersion and capillarity were studied. As a result, it was possible to reduce 40% of the cement consumption by applying the particle packing techniques, resulting in 164 kg of cement/m³. The LCC presented compressive and tensile strengths, at 28 days, of 31 MPa and 2.9 MPa, respectively.
•Cyclic mix-design method allowed to reduce cement consumption by 164 kg/m³.•Reduction of voids promoted by high packing of particle fines.•LCC approached the desired compressive strength in mechanical tests.•Low porosity in the LCC concrete resulted in low absorption values.
Objetiva-se relatar o processo de curadoria realizada em cursos MOOC, disponíveis pela plataforma Lumina educação para todos- Universidade do Rio Grande do Sul (UFRGS), destinados a profissionais da ...saúde, da educação, da assistência social, da segurança e do conselho tutelar, pois o cuidado deve permear áreas multiprofissionais. Trata-se de uma pesquisa documental que buscou obter materiais cientificamente validados por meio de revisão da literatura e dos meios de comunicação, no período compreendido entre junho e julho de 2022. A curadoria, atentou-se primordialmente ao contexto social, em particular à conturbada pandemia do Covid-19, inextricavelmente entrelaçada com a disseminação desenfreada de informações, denominadas infodemias. Ainda assim, para sustentar as discussões, propõe-se a exposição do processo de construção individual de cada curso. A realização das curadorias nos cursos MOOCs gerou uma ampla discussão em relação ao LS, o que permitiu uma abrangência temática para os profissionais da área da saúde.
Palavras-chave: Curadoria de Dados; Educação; Letramento em Saúde; Cursos.
OBJETIVO: Compreender as situações e repercussões de violência doméstica na saúde das mulheres abrigadas em uma casa de passagem. MÉTODO: Trata-se de uma pesquisa descritiva exploratória de caráter ...qualitativa realizada durante novembro e dezembro de 2020. Fizeram parte do estudo oito mulheres que se encontravam na casa de passagem, durante o período de coleta dos dados. Entrevistas individuais em sala reservadas, guiadas por roteiro semiestruturado com questões norteadoras foi a técnica utilizada para a obtenção dos dados, que foram registrados, organizados e posteriormente categorizados por temas. RESULTADOS: Da análise dos dados, emergiram duas categorias, construídas a partir de respostas das entrevistas, sendo: a violência que se repete e as relações entre violência e saúde. A primeira categoria diz respeito ao modo como as mulheres vivenciaram violências em diferentes trajetórias de vida. Já a segunda, refere-se a como essas situações interferem em aspectos relacionados à sua saúde. CONSIDERAÇÕES FINAIS: O estudo revelou, por meio das falas, que há medo na busca de ajuda devido à falta de informações.
Orientador : Profª. Drª. Nayara Soares Klein
Co-orientador : Prof. Dr. Wellington Mazer
Dissertação (mestrado) - Universidade Federal do Paraná, Setor de Tecnologia, Programa de Pós-Graduação em ...Construção Civil. Defesa: Curitiba, 29/04/2016
Inclui referências : f. 119-126
Area de concentração : Materiais e estruturas
Resumo: As questões ambientais que envolvem a produção de concreto vêm sendo muito estudadas, uma vez que o consumo elevado de cimento Portland causa impactos ambientais. A produção de cimento é responsável por cerca de 7% das emissões de gás carbônico (CO2) na atmosfera, geradas por processos industriais no mundo, necessitando também de um alto consumo energético. Uma forma de amenizar isso é investir no produto final, o concreto, consolidando técnicas que envolvam a produção de composições ambientalmente sustentáveis. A redução do consumo de cimento consiste em uma alternativa interessante, principalmente quando se associa esta à utilização de um subproduto pozolânico, como a sílica de casca de arroz. Por esta adição ser um resíduo, é importante que seja prevista a sua destinação correta. No concreto, em substituição parcial do cimento, esse material pode promover o refinamento dos poros e a consequente alteração das propriedades mecânicas e de durabilidade. Por conseguinte, o presente trabalho tem por objetivo utilizar um método de dosagem baseado em técnicas de empacotamento de partículas para dosar, produzir e avaliar as propriedades de um concreto ecológico, cujo consumo de cimento Portland tenha sido reduzido por consequência da aplicação do método de dosagem. Foram realizados estudos de otimização dos agregados e de materiais finos (sílica de casca de arroz e pó de quartzo) para reduzir a quantidade de vazios no concreto e substituir o cimento Portland. As propriedades avaliadas, no estado fresco, foram a consistência, através de slump test, e a massa específica. No estado endurecido, foram estudadas as propriedades de resistência à compressão, resistência à tração por compressão diametral e massa específica. Além disso, foram executados ensaios de absorção de água por imersão e capilaridade, resistividade elétrica e módulo de elasticidade dinâmico através de ultrassom. Estes ensaios estão associados à durabilidade do concreto. As propriedades do concreto ecológico foram, então, comparadas com as obtidas para um concreto convencional. Como resultado do estudo, foi possível produzir dois concretos, cujos consumos de cimento foram reduzidos em 115 kg/m³ (Concreto Ecológico A) e 163 kg/m³ (Concreto Ecológico B). No estado fresco, ambos apresentaram consistência seca, sendo necessário acrescentar aditivo superplastificante e alterar a quantidade de golpes para o adensamento, tendo em vista a elevada compacidade do esqueleto granular. Entretanto, o Concreto Ecológico B apresentou resistência à compressão, aos 28 dias, de 31,0 MPa, estatisticamente equivalente ao concreto de referência que alcançou 35,2 MPa, enquanto que o Ecológico A resultou em 54,1 MPa. Tendências similares foram observadas para o ensaio de resistência à tração. Os ensaios de durabilidade demonstraram baixa porosidade dos concretos ecológicos em relação ao de referência. Por fim, os concretos ecológicos se apresentaram mais caros que o convencional devido ao valor elevado das adições, porém ambos representaram economia de cimento, devido à redução no consumo.
Abstract: Environmental issues evolving cement production have been widely studied, since the high consumption of Portland cement causes environmental impact. Its production is responsible for about 7% of carbon dioxide emissions (CO2) in the atmosphere, generated by industrial processes in the world, also requiring high energy consumption. One way to mitigate this situation is to invest in the final product, concrete, consolidating cementing techniques that involve the production of eco-friendly compositions. The reduction in cement consumption provides an interesting alternative, particularly when this is associated with the use of a pozzolanic by-product, such as rice husk ash. As this admixture is a residue, it is important to predict its correct destination. In concrete, as a replacement for cement, this material can promote pore refinement and modifications of mechanical and durability properties. Therefore, this study aims to use a design method based on particle packing techniques to dose, produce and evaluate the properties of an ecological concrete, which Portland cement consumption has been reduced as a result of the application of the method. Optimization studies of aggregates and fine materials (rice husk ash and quartz powder) were performed to reduce the amount of voids in the concrete and replace Portland cement. The properties evaluated in fresh concrete were consistency through slump test, and density. In the hardened condition, the compressive strength properties were evaluated, like the tensile strength by diametrical compression and density. Furthermore, it was performed tests to evaluate water absorption and capillarity, electrical resistivity and dynamic modulus of elasticity by ultrasound. These assays are associated with the durability of concrete. The properties of ecological concrete were then compared with those obtained for a conventional concrete. As a result of the study, it was possible to produce two concretes, whose cement consumption was reduced in 115 kg/m³ (Ecological Concrete A) and 163 kg/m³ (Ecological Concrete B). In the fresh condition, both presented dry consistency, being necessary to add a superplasticizer. In addition, due to a high packability of the granular skeleton, the concrete densification was complicated, so it was needed to change the amount of strokes to compaction. However, the Ecological Concrete B presented compressive strength at 28 days, of 31.0 MPa, statistically equivalent to the reference concrete which reached 35.2 MPa, while the Ecological Concrete A resulted in 54.1 MPa. Similar tendencies were observed for the tensile strength test. The durability tests showed low porosity of the ecological concretes in relation to the reference. Finally, the ecological concretes performed more expensive than conventional due to the large amount of additions, but both represented cement savings due to reduction in its consumption.
Chagas disease is a neglected tropical disease, caused by the protozoan parasite Trypanosoma cruzi, which affects more than eight million people in Tropical and Subtropical countries especially in ...Latin America. Current treatment is limited to nifurtimox and benznidazole, both with reduced effectiveness and high toxicity. In this work, the n-hexane extract from leaves of Nectandra leucantha (Lauraceae) displayed in vitro antitrypanosomal activity against T. cruzi.
Using several chromatographic steps, four related neolignans were isolated and chemically characterized as dehydrodieugenol B (1), 1-(8-propenyl)-3-3′-methoxy-1′-(8-propenyl)-phenoxy-4,5-dimethoxybenzene (2), 1-(7S)-hydroxy-8-propenyl-3-3′-methoxy-1′-(8′-propenyl)-phenoxy-4-hydroxy-5-methoxybenzene (3), and 1-(7S)-hydroxy-8-propenyl-3-3′-methoxy-1′-(8′-propenyl)-phenoxy-4,5-dimethoxybenzene (4). These compounds were tested against intracellular amastigotes and extracellular trypomastigotes of T. cruzi and for mammalian cytotoxicity. Neolignan 4 showed the higher selectivity index (SI) against trypomastigotes (>5) and amastigotes (>13) of T. cruzi. The investigation of the mechanism of action demonstrated that neolignan 4 caused substantial alteration of the plasma membrane permeability, together with mitochondrial dysfunctions in trypomastigote forms. In silico studies of pharmacokinetics and toxicity (ADMET) properties predicted that all compounds were non-mutagenic, non-carcinogenic, non-genotoxic, weak hERG blockers, with acceptable volume of distribution (1.66–3.32 L/kg), and low rodent oral toxicity (LD50 810–2200 mg/kg). Considering some clinical events of cerebral Chagas disease, the compounds also demonstrated favorable properties, such as blood-brain barrier penetration. Unfavorable properties were also predicted as high promiscuity for P450 isoforms, high plasma protein binding affinity (>91%), and moderate-to-low oral bioavailability. Finally, none of the isolated neolignans was predicted as interference compounds (PAINS). Considering the promising chemical and biological properties of the isolated neolignans, these compounds could be used as starting points to develop new lead compounds for Chagas disease.
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•Neolignans 1–4 were isolated from leaves of Nectandra leucantha (Lauraceae).•Neolignans 1–4 displayed activity against T. cruzi and reduced cytotoxicity.•Neolignan 4 showed selectivity against trypomastigotes (>5) and amastigotes (>13).•Neolignan 4 alters plasma membrane permeability and mitochondrial dysfunction.•None of the isolated neolignans was predicted as interference compounds (PAINS).
To analyze how nephrotic syndrome (NS) correlates to increased intracranial pressure (ICP), and to present a case of an adult patient whose initial manifestation of NS was cephalalgia, with the later ...identification of raised ICP.
Data were retrospectively retrieved from the patient’s record, and a literature search with the keywords “nephrotic syndrome”, “intracranial hypertension” and “headache” was conducted in PubMed and Embase.
This is a rare description of co-occurrence of NS and raised ICP in a 48-year-old man, in which ICP normalizes after NS remits. There is no known cause for the raised ICP of our patient. Ten reports (n = 13) of concomitant occurrence of increased ICP and NS were described in the literature, both in children and adults. Cerebral venous thrombosis (CVT) was the most likely underlying cause for the majority of them. For one patient, the underlying cause was meningoencephalitis. Finally, in one case, the cause is unknown, but CVT was not discarded.
The early suspicion of elevated ICP is warranted in patients with new-onset headache and NS. It is possible that NS could both directly and indirectly lead to increased ICP through yet unknown mechanisms, although this direct causal relationship cannot be currently established.
•The early suspicion of elevated ICP is warranted in patients with new-onset headache and NS.•It is possible that NS could both directly and indirectly lead to increased ICP through yet unknown mechanisms.•However, this direct causal relationship cannot be currently established.•We could hypothesize that the hyperaldosteronism originated from the RAAS system led to the increased ICP of our patient.•Notwithstanding, it would be too speculative to try to disseminate any possible pathophysiological connections at this moment.
This paper presents the impacts caused by the integration of variable speed wind turbines on long-term voltage stability. The technologies used are fully rated converter (FRC) and doubly fed ...induction generator (DFIG) with two control strategies: grid-side converter (GSC) at unity power factor, which is usually adopted, and GSC controlling reactive power. Also, this paper considers wind turbines capability curves and its variable limits, since they are subject to several limitations that changes with the operating point and wind speed. This study also considers the dynamic models of over excitation limiter (OEL) and on-load tap changers (OLTC) combined with static and dynamic loads using time domain simulations. Different penetration levels of wind generation are analyzed. The results show that long-term voltage stability can be improved when GSC of DFIG is controlling reactive power. Moreover, the capability curve plays an important role in this analysis since reactive power is a key requirement to maintain voltage stability.
•The SVC applied to a DFIG-based wind park postponing voltage instability.•The SVC applied to RSC can impose a PWM index limitation of the GSC.•SVC leads the GSC to absorb significant amount of ...reactive power.•SVC leads the GSC to lose capability of injecting additional reactive power.•Two novel control strategies assist the SVC applied in a DFIG-based wind park.
This paper investigates the use of secondary voltage control (SVC) in a wind park based on doubly fed induction generator (DFIG) and its effect on long-term voltage stability. The performance of the SVC applied to wind park is compared with the case when only the primary voltage control (PVC) is adopted. A detailed analysis is conducted with time-domain simulations, considering high and low wind speed regimes, control variable limits of wind generators, static and dynamic loads, and dynamic models of overexcitation limiter (OEL) and load tap changing (LTC) transformer. Based on the results, the use of secondary voltage control in a DFIG-based wind park can postpone long-term voltage instability. Further, some interesting findings were obtained showing that SVC can lead the grid-side converter (GSC) of DFIG to absorb a significant amount of reactive power and lose the capability of injecting additional reactive power. To address this problem, two novel auxiliary control strategies are presented, and the results indicate the effectiveness of the proposed strategies in postponing voltage instability.
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