Structure-property relationships in high barrier multilayer film/foam systems

Thermoplastic foams nowadays are widely used in a variety of applications, such as packaging, construction, and the automotive industry because of their wide range of properties such as lightweight, excellent strength/weight ratio, insulation properties, energy absorption performance, and material cost. However, there are still issues on the gas barrier and mechanical properties in use because of the cellular structure. This work targeted to unveil the processing-structure-property relationships of three film/foam multilayer polymeric systems with diverse transport properties. The first part of the thesis (Chapter 2) focuses on the understanding of the effect of the number of layers and composition on mechanical properties and barrier properties of multilayer film/foam material with alternating ethylene-vinyl alcohol copolymer (EVOH) film layers and low-density polyethylene (LDPE) foam layers. Tensile properties of the film/foams at elevated temperatures were used to optimize thermoforming conditions. Uniaxial orientation was discovered as an efficient approach to evaluate the potential for thermoforming. Oxygen transmission showed a strong correlation with the thickness reduction which could be used as an indicator for barrier properties of the packaging materials. Film/foam materials with 32 layers demonstrated optimum performance with low oxygen transmission along with high drawing capability. In the third chapter, the previous system (Chapter 2) was innovated with high-density polyethylene (HDPE) skin layer. High oxygen and water vapor barrier film/foam system had been developed using multilayer co-extrusion technology. The film/foams contained alternating low-density polyethylene (LDPE) foam layers and ethylene–vinyl alcohol (EVOH) copolymer film layers with HDPE skin layer. The lightweight film/foams showed oxygen and water vapor transmission rate are correlated with the EVOH film layer and HDPE skin layer composition. The layered film/foam was successfully thermoformed at 80 °C with low oxygen transmission along with high drawing capability. The fourth chapter introduces a novel approach, to produce PLA/PLA multilayer film/foams structures having 16, 32, and 64 alternating layers. The lightweight multilayered PLA/PLA film/foam has a unique solid/porous alternating horizontal architecture, in which the film layers can effectively control the growth of the cells and suppress the premature rupture of cells during coextrusion process. Tensile properties at elevated temperatures of the PLA film were used to optimize thermoforming conditions. The effects of annealing temperature and time on the crystallinity and oxygen permeability of PLA/PLA multilayer film/foams were investigated. Oxygen transmission showed a strong correlation with the crystallinity of PLA/PLA multilayer film/foam. The material demonstrated high performance with low oxygen transmission which could be used as high barrier material

Bound states in disclinated graphene with Coulomb impurities in the presence of a uniform magnetic field

AbstractIn this contribution, we study the effects caused by an impurity on the quantum dynamics of massive excitations in a disclinated graphene in the presence of an external magnetic field. Within a continuum approach, the problem is mathematically modeled by the definition of a special vector potential containing all the information about the topology and the interacting fields. The presence of disclination is introduced by a term in the Dirac equation that translates the appearance of a phase associated with the transport of the spinor around the apex of the cone. We solve exactly the Dirac equation for this problem and the eigenvalues are obtained. We observe the influence of the disclination on the spectrum of energy and the allowed values of magnetic field

Degradação de corantes reativos e remediação de efluentes têxteis por processos avançados envolvendo ferro metálico

Orientador: Patricio Peralta-ZamoraDissertação (mestrado) - Universidade Federal do Paraná, Setor de Ciências Exatas, Programa de Pós-Graduação em Química. Defesa: Curitiba, 2006Inclui bibliografi

TABAGISMO COMO FATOR DE RISCO PARA O CÂNCER DE PRÓSTATA NA POPULAÇÃO DO SUDOESTE DA BAHIA

 O câncer de próstata é considerado a quarta neoplasia mais comum em todo mundo e a segunda mais comum entre homens. No Brasil, foram diagnosticados 61.200 novos casos em 2016, correspondendo a um risco de 61,82 novos casos a cada 100 mil homens. Idade avançada, etnia e o histórico familiar são fatores de risco confirmados para a doença, o tabagismo, entretanto, consta como um fator de risco ainda incerto, sendo sua relação com o câncer de próstata bastante controversa na literatura. O presente estudo teve como objetivo avaliar a possível relação entre o tabagismo e câncer de próstata na população masculina com mais de 50 anos no sudoeste da Bahia. Foi realizado um estudo de caso controle, em que, foram selecionados 319 indivíduos do sexo masculino com idade igual ou superior a 50 anos. A coleta de dados se deu por meio de aplicação de questionários, sendo as entrevistas realizadas no ambiente da unidade de saúde onde se encontrava o sujeito de pesquisa. Não foi encontrada relação entre o tabagismo câncer de próstata (OR= 0.80, IC95%: 0,39 – 1,61) (p= 0,32), entretanto, observou-se relação significativa com o tabagismo passado (OR= 2,52; IC 95%, 1,52 – 4,18) (p=0,0002) em indivíduos que mantiveram o hábito por mais de 30 anos (OR= 8,25; IC95%, 3,92 -17,37) (p<0,0001). Este estudo demonstrou existir maior risco de câncer de próstata entre ex-fumantes. Aponta também que uso de tabaco por período superior a 30 anos aumenta a chance em desenvolver o câncer de próstata

A percepão dos gestores de MES e EPPS do ramo de materiais de construção sobre a relevância das informações geradas pelo sistema de informação

In a globalized scenario, there are uncertainties and great competitiveness between companies, it is necessary to have accurate, necessary and reliable information so that managers can make a decision and stand out in the market. This research had as general objective to analyze the perception of the managers of the micro and small companies, of the branch of construction materials, in Tomé-Açu, and in the district of Quatro Bocas, Pará, about the relevance of the information generated by the information system managing your business and supporting decision making. Through an exploratory and descriptive research, with a qualitative and quantitative approach, it was researched in the month of September 2019, in 14 companies in the branch of construction materials, in the city of the research, in order to analyze the perception of managers regarding the use information system. It was found that 71.4% of companies use some information system, and of those that do, it was concluded that an information system, which is reliable, capable of meeting the needs of its managers, can provide information that if used in a correct, ensures the development and continuity of the company in the market, thus ensuring the success of the enterprise.                                       Em um cenário globalizado, existem incertezas e uma grande competitividade entre as empresas, é necessário ter informações precisas, necessárias e confiáveis para que os gestores possam tomar uma decisão e se sobressair no mercado. Esta pesquisa teve como objetivo geral analisar a percepção dos gestores das microempresas e empresas de pequeno porte, do ramo de materiais de construção, em Tomé-Açu, e no distrito de Quatro Bocas, Pará, sobre a relevância das informações geradas pelo sistema de informação no gerenciamento de seus negócios e no suporte à tomada de decisões. Por meio de uma pesquisa de caráter exploratório e descritiva, de abordagem qualitativa e quantitativa, foi pesquisado no mês de setembro de 2019, em 14 empresas do ramo de materiais de construção, na cidade da pesquisa, com intuito de analisar a percepção dos gestores quanto a utilização do sistema de informação. Foi verificado que 71,4% das empresas utilizam algum sistema de informação, e das que utilizam, concluiu-se que um sistema de informação, que seja confiável, capaz de suprir as necessidades de seus gestores, pode fornecer informações que se utilizadas de forma correta, garante o desenvolvimento e a continuidade da empresa no mercado, garantindo assim o sucesso do empreendimento.   &nbsp

Habilidades dos recém-formados em Contabilidade: análise da percepção dos profissionais de recrutamento

Estudos recentes indicam maior necessidade de qualificação dos profissionais contábeis brasileiros, principalmente acerca de suas soft skills. Para que os profissionais em formação (estudantes de ciências contábeis) possam atingir as expectativas dos recrutadores, é necessário, primeiramente, identificar o perfil traçado por aqueles profissionais no preenchimento das vagas demandadas pelo mercado. Diante desse cenário, o presente estudo objetivou identificar as principais competências e habilidades requisitadas aos profissionais contábeis vis-à-vis aquelas encontradas pelos recrutadores em geral, por meio de uma websurvey com profissionais de recrutamento e gerentes de recursos humanos, visando obter o perfil esperado dos profissionais formados em Contabilidade. O presente estudo contribui para a discussão das habilidades e competências dos profissionais de contabilidade, bem como apresenta potencial reflexivo para os coordenadores de curso que desejam aumentar seu nível de empregabilidade e diálogo com profissionais de recrutamento e seleção

Single Er3+, Yb3+: KGd3F10 Nanoparticles for Nanothermometry

Among several optical non-contact thermometry methods, luminescence thermometry is the most versatile approach. Lanthanide-based luminescence nanothermometers may exploit not only downshifting, but also upconversion (UC) mechanisms. UC-based nanothermometers are interesting for biological applications: they efficiently convert near-infrared radiation to visible light, allowing local temperatures to be determined through spectroscopic investigation. Here, we have synthesized highly crystalline Er3+, Yb3+ co-doped upconverting KGd3F10 nanoparticles (NPs) by the EDTA-assisted hydrothermal method. We characterized the structure and morphology of the obtained NPs by transmission electron microscopy, X-ray diffraction, Raman spectroscopy, and dynamic light scattering. Nonlinear spectroscopic studies with the Er3+, Yb3+: KGd3F10 powder showed intense green and red emissions under excitation at 980 and 1,550 nm. Two- and three-photon processes were attributed to the UC mechanisms under excitation at 980 and 1,550 nm. Strong NIR emission centered at 1,530 nm occurred under low 980-nm power densities. Single NPs presented strong green and red emissions under continuous wave excitation at 975.5 nm, so we evaluated their use as primary nanothermometers by employing the Luminescence Intensity Ratio technique. We determined the temperature felt by the dried NPs by integrating the intensity ratio between the thermally coupled H-2(11/2)-> I-4(15/2) and S-4(3/2)-> I-4(15/2) levels of Er3+ ions in the colloidal phase and at the single NP level. The best thermal sensitivity of a single Er3+, Yb3+: KGd3F10 NP was 1.17% at the single NP level for the dry state at 300 K, indicating potential application of this material as accurate nanothermometer in the thermal range of biological interest. To the best of our knowledge, this is the first promising thermometry based on single KGd3F10 particles, with potential use as biomarkers in the NIR-II region