Desenvolvimento de membranas eletrofiadas de poli (fluoreto de vinilideno) com polipirrol para aplicação em sensores de compressão

Tese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Ciência e Engenharia de Materiais, Florianópolis, 2014Nesta tese foram desenvolvidas membranas eletrofiadas constituídas de poli (fluoreto de vinilideno) (PVDF) e polipirrol (PPy) com propriedades eletromecânicas para utilização como materiais eletroativos em sensores de compressão. As membranas eletrofiadas foram preparadas a partir de duas rotas distintas: i) recobrimento da membrana eletrofiada de PVDF com PPy a partir da polimerização oxidativa in situ do monômero; ii) técnica de eletrofiação direta, em que as membranas foram obtidas a partir da eletrofiação de uma mistura contendo o PVDF e o PPy dopado com ácido dodecil benzeno sulfônico (DBSA). Foi investigado o efeito dos diferentes parâmetros de eletrofiação do PVDF, as condições reacionais para o incorporação do PPy na superfície das fibras eletrofiadas de PVDF e o efeito da quantidade de PPy na estrutura e propriedades das membranas eletrofiadas. As propriedades físico-químicas e as variações da resistividade elétrica durante repetidos ciclos de compressão e descompressão das membranas eletrofiadas foram investigadas e comparadas com membranas densas de PVDF/PPy. DBSA. A morfologia, resistividade elétrica, propriedades mecânicas e resposta eletromecânica foram substancialmente influenciadas pelo método de preparação e pela quantidade de PPy presente na membrana. As membranas obtidas pelos diferentes métodos apresentaram variação na resistividade elétrica sob tensão de compressão, porém, a magnitude da resposta e sua reprodutibilidade foi significativamente diferente de acordo com a morfologia e a quantidade de PPy presente na membrana. Membranas eletrofiadas de PVDF/PPy. DBSA obtidas por eletrofiação direta apresentaram variação na resistividade elétrica superior às membranas obtidas pelos outros métodos. A máxima variação na resistividade elétrica foi obtida para a membrana eletrofiada de PVDF/PPy. DBSA contendo 13 %m de PPy. DBSA, com variações de 9 ordens de grandeza, apresentando uma redução de 1016 até 107 O.cm, com a aplicação de tensão de compressão de até 5 MPa. Essa peculiar resposta pode ser atribuída à formação de uma rede condutora induzida pela tensão de compressão. Considerando as significativas mudanças na resistividade e a reprodutibilidade da resposta depois de repetidos ciclos de compressão e descompressão, essas membranas eletrofiadas tem grande potencial para serem utilizadas como materiais sensíveis a esforços compressivos.Abstract: In this thesis were developed non-woven electrospun mats of poly(vinylidene fluoride) (PVDF) and polypyrrole (PPy) with pressure-sensitive electrical resistivity for pressure sensors applications. The electrospun mats were produced by two different approaches: i) an indirect method, in which the PVDF electrospun mats were coated with PPy through pyrrole oxidative polymerization and ii) direct electrospinning technique, in which fibers were electrospun from a mixture containing PVDF, and PPy particles synthesized by using dodecylbenzenesulfonic acid (DBSA) as a dopant. The effect of PVDF electrospinning parameters, the reaction conditions to coat the electrospun PVDF mats surface with PPy, and the PPy amount on the structure and properties of electrospun mats were investigated. It were investigated the physicochemical properties and the electrical resistivity changes during loading-unloading compressive cycles of electrospun mats and compared with PVDF/PPy. DBSA dense films. The morphology, electrical resistivity, mechanicals properties and electromechanical response were significantly influenced by the preparation method and the PPy amount present on the mat. The mats obtained through different techniques displayed electrical resistivity changes under compressive stress. However, the magnitude of response and the reproducibility were plenty different according to the morphology and PPy amount on the mat. PVDF/PPy. DBSA electropsun mats prepared by direct electrospinning showed higher electrical resistivity changes than the membranes obtained by others techniques. The maximum sensitivity was obtained for the PVDF/PPy. DBSA electrospun mat containing 13 wt% of PPy. DBSA, and manifests an electrical resistivity drop of 9 orders of magnitude, i.e. from 1016 to 107 O.cm under application of a compressive stress of 5 MPa. This peculiar response can be attributed to the formation of stress-induced conducting pathways in the electrospun network. Considering the remarkable resistivity change and the reproducibility of the phenomenon after repeated loading-unloading cycles, these mats have potential to be used as pressure-sensitive materials

Análise experimental de compósitos de poliuretano derivado de óleo de mamona e fibras de bananeira

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Ciência e Engenharia de Materiais, Florianópolis, 2011A crescente preocupação global com relação ao meio ambiente e preservação de recursos naturais não renováveis têm incentivado pesquisas em diferentes áreas buscando a utilização de materiais oriundos de fontes renováveis. Nesse contexto, a utilização de fibras vegetais e poliuretano derivado do óleo de mamona em compósitos poliméricos mostram-se como uma boa alternativa. Este trabalho tem como objetivo avaliar a influência da fração volumétrica, comprimento e tratamento alcalino das fibras de bananeira nas propriedades de compósitos com poliuretano derivado do óleo de mamona. As fibras de bananeira foram modificadas superficialmente com solução de hidróxido de sódio 10% por 1, 4 e 8 horas e caracterizadas por espectroscopia no infravermelho por transformada de Fourier (FTIR), microscopia eletrônica de varredura (MEV), análise termogravimétrica (TG), resistência a tração e densidade. A partir dos espectros FTIR observou-se que com apenas 1 hora de tratamento já ocorreu modificações superficiais e na estrutura química das fibras. Compósitos poliméricos, com diferentes frações volumétricas e comprimentos de fibras sem e com tratamento alcalino por 1 hora, foram preparados a partir da moldagem por compressão. Os compósitos foram analisados por MEV, TG, calorimetria exploratória diferencial (DSC), FTIR, resistência a tração, absorção de água e ensaio de pull-out. Observou-se que o tratamento alcalino das fibras resultou em aumento na resistência a tração e módulo elástico dos compósitos, devido à mudança na morfologia da superfície das fibras tratadas, somado à maior concentração de grupos hidroxila livres que promovem maior adesão mecânica e química, respectivamente, entre as fibras e a matriz. Com o aumento da fração volumétrica e comprimento das fibras também se verificou uma melhora nas propriedades mecânicas dos compósitos

Regulation of mating in the budding yeast Saccharomyces cerevisiae by the zinc cluster proteins Sut1 and Sut2

This article is made available through the Brunel Open Access Publishing Fund. Copyright @ The Authors. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.The zinc cluster proteins Sut1 and Sut2 play a role in sterol uptake and filamentous growth in the budding yeast Saccharomyces cerevisiae. In this study, we show that they are also involved in mating. Cells that lack both SUT1 and SUT2 were defective in mating. The expression of the genes NCE102 and PRR2 was increased in the sut1 sut2 double deletion mutant suggesting that Sut1 and Sut2 both repress the expression of NCE102 and PRR2. Consistent with these data, overexpression of either SUT1 or SUT2 led to lower expression of NCE102 and PRR2. Furthermore, expression levels of NCE102, PRR2 and RHO5, another target gene of Sut1 and Sut2, decreased in response to pheromone. Prr2 has been identified as a mating inhibitor before. Here we show that overexpression of NCE102 and RHO5 also reduced mating. Our results suggest that Sut1 and Sut2 positively regulate mating by repressing the expression of the mating inhibitors NCE102, PRR2 and RHO5 in response to pheromone.Deutsche Forschungsgemeinschaf

Screen printing of cotton fabric with hydrochromic paste: evaluation of color uniformity, reversibility and fastness properties

Smart textiles are promising for the future of the textile industry, providing natural fibers with attractive and interactive features. Within this context, it is possible to emphasize the chromic materials, as, for example, the hydrochromic, which alter their visual properties (color) through an external stimulus (water). The purpose of this work is to functionalize and characterize cotton knitted fabric with hydrochromic agent studying the reversibility and fastness properties of the print. It was observed that the particles are well dispersed and adhered to the natural fiber surface and did not display significant changes in the color after subsequent washing and rubbing fastness cycles.智能纺织品为纺织工业的未来带来了希望, 它提供了具有吸引力和互动功 能的天然纤维. 在这种情况下, 可以强调铬材料, 例如水变色材料, 通过外部 刺激（水）改变其视觉特性（颜色）. 本研究的目的是利用水致变色剂对 棉针织物进行功能化和表征, 研究印花的可逆性和牢度性能. 经观察, 这些 颗粒在天然纤维表面分散良好, 粘附在纤维表面, 在随后的洗涤和摩擦牢度 循环后, 颜色没有明显变化

Evaluation of the Properties of Iron Oxide-Filled Castor Oil Polyurethane

The aim of this study was to obtain and evaluate the electrical, thermal and mechanical properties of iron oxide-filled castor oil polyurethane (PU/Fe2O3). The iron oxide used in this study was a residue derived from the steel pickling process of a Brazilian steel rolling industry. Polymeric composites with different iron oxide volume fractions (2.5, 5.0, 7.5, 10.0 and 12.5%) were prepared through the casting process followed by compression molding at room temperature. The composites were analyzed by FTIR, XRD and densities, tensile strength, Young’s modulus, electrical and thermal conductivities measurements. By increasing the iron oxide content, the apparent density, tensile strength, Young’s modulus and electrical conductivity values of the composites were also increased. The iron oxide additions did not change significantly the value of thermal conductivity (from 0.191 W.mK–1 for PU up to 0.340 W.mK–1 for PU enriched with 12.5% v/v of iron oxide). Thus, even at the higher iron oxide concentration, the compounds as well as the pure polyurethane can be classified as thermal insulators

Psychosocial burden and professional and social support in patients with hereditary transthyretin amyloidosis (ATTRv) and their relatives in Italy

Hereditary transthyretin amyloidosis (hATTR), alias ATTR variant (ATTRv) is a severe and disabling disease causing sensory and motor neuropathy, autonomic dysfunction, and cardiomyopathy. The progressive decline of patient's functional autonomy negatively affects the patient's quality of life and requires increasing involvement of relatives in the patient's daily life. Family caregiving may become particularly demanding when the patient is no longer able to move independently. This study is focused on the psychosocial aspects of ATTRv from the patient and relative perspectives. In particular, it explored: the practical and psychological burdens experienced by symptomatic patients with ATTRv and their key relatives and the professional and social network support they may rely on; whether burden varied in relation to patients' and relatives' socio-demographic variables, patients' clinical variables, and perceived professional and social network support; and, any difference in burden and support between patients and their matched relatives

Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London

The polymorphism L412F in TLR3 inhibits autophagy and is a marker of severe COVID-19 in males

The polymorphism L412F in TLR3 has been associated with several infectious diseases. However, the mechanism underlying this association is still unexplored. Here, we show that the L412F polymorphism in TLR3 is a marker of severity in COVID-19. This association increases in the sub-cohort of males. Impaired macroautophagy/autophagy and reduced TNF/TNFα production was demonstrated in HEK293 cells transfected with TLR3L412F-encoding plasmid and stimulated with specific agonist poly(I:C). A statistically significant reduced survival at 28 days was shown in L412F COVID-19 patients treated with the autophagy-inhibitor hydroxychloroquine (p = 0.038). An increased frequency of autoimmune disorders such as co-morbidity was found in L412F COVID-19 males with specific class II HLA haplotypes prone to autoantigen presentation. Our analyses indicate that L412F polymorphism makes males at risk of severe COVID-19 and provides a rationale for reinterpreting clinical trials considering autophagy pathways. Abbreviations: AP: autophagosome; AUC: area under the curve; BafA1: bafilomycin A1; COVID-19: coronavirus disease-2019; HCQ: hydroxychloroquine; RAP: rapamycin; ROC: receiver operating characteristic; SARS-CoV-2: severe acute respiratory syndrome coronavirus 2; TLR: toll like receptor; TNF/TNF-α: tumor necrosis factor