UV-LED curable acrylic films containing phosphate glass powder: effect of the filler loading on the thermal, optical, mechanical and flame retardant properties

In this work, we thoroughly investigate the effects of the incorporation of a phosphate glass micrometric powder on the morphology, as well as on the thermal, optical, mechanical and flame retardant properties of UV-LED curable acrylic films. To this aim, the filler loading was changed within 10 and 50 wt.%. UV-LED initiated curing was selected as a fast and reliable system, as the standard UV-curing process was not suitable because of the presence of the glass powder that decreased the quantum efficiency during the UV exposure, hence preventing the transformation of the liquid system into a solid network. The glass powder slightly increased the glass transition temperature of the acrylic network, hence showing a limited effect on the chain segments mobility; besides, increasing filler loadings were responsible for a progressive decrease of the transparency of films, irrespective of a marginal effect on their refractive index. Conversely, the presence of increasing amounts of phosphate glass improved the thermal and thermo-oxidative stability of the cured products. Besides, phosphate glass was capable of remarkably enhancing the flame retardance of the acrylic network at 50 wt.% loading, which achieved self-extinction in vertical flame spread tests (and was V-0 rated). This formulation, as assessed by forced-combustion tests, also displayed a remarkable decrease of peak of Heat Release Rate and Total Heat Release (by 44 and 33%, respectively) and of Total Smoke Release and Specific Extinction Area (by 53 and 56%, respectively). Further, the filler promoted an increase of the stiffness and surface hardness of the films, at the expense of a decrease in ductility. All these findings may justify the potential use of these composite films as flame retardant coatings for different flammable substrates

N- and S-doped carbons derived from polyacrylonitrile for gases separation

The CO2 capture using adsorption can reduce the carbon footprint, increasing the sustainability of the process without the production of wastes present in commonly used industrial operations. The present research work analyses the effect of the doping-agents incorporation in carbon materials upon adsorption and separation of gases, specifically for carbon dioxide and nitrogen. The carbons precursor was polyacrylonitrile (PAN), which enabled the incorporation of nitrogen atoms in the structure, whereas sulphur doping was reached using pure sulphur after the carbonisation step. The influence of several variables (such as temperature or pressure) and characteristics of synthesised materials (mainly corresponding to surface characteristics) on carbon dioxide separation has been evaluated. Adsorption isotherms were determined for each gas (CO2 and N2) at different temperatures and pressures. Different adsorption models were evaluated to fit the experimental data. In general, the Toth isotherm described better the adsorption for both gases. Important parameters such as CO2/N2 selectivity and heat of adsorption were determined using the IAS theory and the experimental isotherms at different temperatures, respectively. Non-activated carbons generated from PAN carbonisation without sulphur addition showed the highest values of selectivity (up to 400) and adsorption heat (up to 40 kJ mol−1), mainly at low pressures and at low carbon dioxide uptakes, respectively. Furthermore, thanks to their high adsorption capacity, these carbons can be applied for carbon dioxide separation from mixtures with nitrogen

UV-LED Curable Acrylic Films Containing Phosphate Glass Powder: Effect of the Filler Loading on the Thermal, Optical, Mechanical and Flame Retardant Properties

In this work, we thoroughly investigate the effects of the incorporation of a phosphate glass micrometric powder on the morphology, as well as on the thermal, optical, mechanical and flame retardant properties of UV-LED curable acrylic films. To this aim, the filler loading was changed within 10 and 50 wt.%. UV-LED initiated curing was selected as a fast and reliable system, as the standard UV-curing process was not suitable because of the presence of the glass powder that decreased the quantum efficiency during the UV exposure, hence preventing the transformation of the liquid system into a solid network. The glass powder slightly increased the glass transition temperature of the acrylic network, hence showing a limited effect on the chain segments mobility; besides, increasing filler loadings were responsible for a progressive decrease of the transparency of films, irrespective of a marginal effect on their refractive index. Conversely, the presence of increasing amounts of phosphate glass improved the thermal and thermo-oxidative stability of the cured products. Besides, phosphate glass was capable of remarkably enhancing the flame retardance of the acrylic network at 50 wt.% loading, which achieved self-extinction in vertical flame spread tests (and was V-0 rated). This formulation, as assessed by forced-combustion tests, also displayed a remarkable decrease of peak of Heat Release Rate and Total Heat Release (by 44 and 33%, respectively) and of Total Smoke Release and Specific Extinction Area (by 53 and 56%, respectively). Further, the filler promoted an increase of the stiffness and surface hardness of the films, at the expense of a decrease in ductility. All these findings may justify the potential use of these composite films as flame retardant coatings for different flammable substrates

Estudo da prevalência de hipoacusia em indivíduos com diabetes mellitus tipo 1 Hearing loss prevalence in patients with diabetes mellitus type 1

Diabetes mellitus (DM) é uma doença crônica causada pela não produção e uso inadequado de insulina. Enfermidade crônico-degenerativa. Complicações crônicas do DM, no sistema auditivo, podem causar atrofia do gânglio espiral, degeneração da bainha de mielina do VIII par craniano, diminuição de fibras nervosas na lâmina espiral ou espessamento das paredes capilares da estria vascular e das pequenas artérias. OBJETIVO: Verificar os limiares auditivos em indivíduos portadores de DM tipo 1. MATERIAL E MÉTODOS: Estudo clínico envolvendo 60 indivíduos, divididos em Grupo Estudo (GE) e Grupo Controle (GC), indivíduos diabéticos e não diabéticos. Realizada anamnese, exame físico, otorrinolaringológico e exame audiométrico. RESULTADOS:Quanto aos limiares de audibilidade, no GE, houve diferença estatisticamente significante nas frequências 250, 500, 10.000, 11.200, 12.500, 14.000 e 16.000 Hz em ambas as orelhas e médias das orelhas. Na comparação dos GE e GC, houve diferença estatisticamente significativa com maior probabilidade de ocorrência de hipoacusia em alguma frequência independente da orelha testada no GE. CONCLUSÕES: Houve diferenças estatisticamente significativas nos achados audiológicos no GE quando comparado com GC, justificando avaliação audiológica completa em pacientes diabéticos tipo 1, incluindo audiometria de altas frequências.<br>Diabetes mellitus (DM) is a chronic degenerative disease that impairs normal insulin production and use. DM chronic auditory complications may include spiral ganglion atrophy, degeneration of the vestibulocochlear nerve myelin sheath, reduction of the number of spiral lamina nerve fibers, and thickening of the capillary walls of the stria vascularis and small arteries. OBJECTIVE: This paper aims to verify the hearing thresholds of individuals with type 1 DM. MATERIALS AND METHODS: Sixty patients were enrolled in this trial and divided into case and control groups featuring diabetic and non-diabetic subjects respectively. All individuals were interviewed and underwent physical examination, ENT examination, and audiometric tests. RESULTS: Statistically significant difference was observed in hearing thresholds of case group subjects at 250, 500, 10,000, 11,200, 12,500, 14,000 and 16,000 Hz for both ears and ear average. Case group subjects had higher likelihood of having hypacusis at any frequency regardless of ear than controls. CONCLUSION: Statistically significant differences were seen in the audiological findings of case group subjects when compared to controls. Thorough audiological examination including high frequency audiometry is required for subjects with diabetes mellitus type 1

Investigação das falhas técnicas verificadas em próteses auditivas de usuários de um programa público de saúde auditiva

Objetivo analisar as falhas t&#233;cnicas em pr&#243;teses auditivas de um grupo de usu&#225;rios do Programa de Sa&#250;de Auditiva de uma Universidade em Curitiba. M&#233;todos analisou-se o relat&#243;rio t&#233;cnico de 104 pr&#243;teses de usu&#225;rios que compareceram ao servi&#231;o para a consulta de acompanhamento. Resultados o relat&#243;rio apontou para defeitos em: 21% receptor; 15% caixa; 12% suspens&#227;o; 9% microfone; 2% amplificador. Com rela&#231;&#227;o &#224; causa prov&#225;vel do defeito: 58% desgaste em fun&#231;&#227;o do tempo de uso; 25% umidade; 23% mau uso. Quanto ao valor dos consertos: m&#237;nimo de R44,00 para revisão e limpeza (36%) e máximo de R900,00 para substitui&#231;&#227;o de pe&#231;as (9,6%); 21% da amostra teve o or&#231;amento realizado entre R$100,00 e R$500,00; 37% dos aparelhos foram substitu&#237;dos. Conclus&#227;o Os defeitos detectados deveram-se a problemas de manuseio entre os usu&#225;rios recentes, e desgaste entre os usu&#225;rios mais antigos

Biodegradation of unvulcanized natural rubber by microorganisms isolated from soil and rubber surface: A preliminary study

The Natural rubber (NR) biodegradation by three microorganisms has been evaluated: a yeast (Rhodotorula mucilaginosa) and a bacterium (Pseudomonas sp.), isolated in a liquid culture from soil, and a filamentous fungus (Alternaria alternata), isolated on a solid culture from an NR surface, were tested. The biodegradation was conducted for four months in liquid culture, at 30C, in agitated and stationary conditions, using a Mineral Salt Medium with NR as the only carbon source. The growth behaviour of the yeast and the bacterium was evaluated by means of optical density measurements (OD650). At the end of the incubation, the dry weight biomass of the microorganisms was measured. R. mucilaginosa showed a higher biomass production in the agitated culture, while a more efficient production was observed in static conditions for the Pseudomonas and A. alternata strains. The highest enzymatic activity of Lignin peroxidase (LiP) and Manganese-dependent peroxidase (MnP) was obtained in static conditions for A. alternata. The laccase production was probed by guaiacol oxidative polymerization on agar plates. The microorganism biodegradation capability was assessed through a combination of SEM analysis, FTIR-ATR spectroscopy, and Size Exclusion Chromatography techniques. An extended mycelium-substrate interphase and a decrease in the NR molecular weight were observed

Relaxation Dynamics in Polyethylene Glycol/Modified Hydrotalcite Nanocomposites

Polyethylene glycol-based nanocomposites containing an organo-modified hydrotalcite with loadings ranging from 0.5 to 5 wt.% were prepared by melt mixing performed just above the melting point of the polymer matrix. In these conditions, the dispersion of the nanofiller within the polymer matrix was quite homogeneous as revealed by TEM analyses. The effect of various thermal treatments and filler loadings was thoroughly investigated by means of rheological, morphological and gas chromatography-mass spectrometry, hyphenated to thermogravimetry analysis tests. Unfilled polyethylene glycol exhibited a continuous decrease in complex viscosity upon heating. In contrast, the complex viscosity of nanocomposites containing nanofiller loadings higher than 1 wt.% showed first a decrease, followed by an increase in the complex viscosity as the temperature increases, exhibiting a minimum between 130 and 140 &#176;C. Annealing at 180 &#176;C for different times further increased the viscosity of the system. This unusual behavior was explained by the occurrence of grafting reactions between the &#8315;OH terminal groups of the polyethylene glycol chains and the hydroxyl groups of the organo-modified filler, thus remarkably affecting the relaxation dynamics of the system

EFFECT OF FILLER ASPECT RATIO AND TEMPERATURE ON THE RELAXATION DYNAMICS IN PEG-BASED NANOCOMPOSITES

Polymer-based nanocomposites have attracted a growing attention in the last few years, as the incorporation of solid nanoparticles into a soft polymeric matrix allows obtaining multi-functional materials with tailored properties, potentially suitable for advanced applications. However, the final properties of the resulting composite systems are strictly dependent on several factors, including the shape and size of the embedded nanoparticles and the interactions taking place between polymer macromolecules and nanofillers (2). In addition, the polymer/nanofillers and nanofillers/nanofillers interactions can significantly affect the viscoelastic properties of polymer-based materials, which have a significant importance from a technological point of view. Furthermore, the study of the rheological response of polymeric nanocomposites can be used as a tool to investigate their microstructure, offering the possibility to gain a fundamental understanding of their structure-properties relationships. In this work, nanostructured composites based on a low molecular weight polyethylene glycol (PEG) and containing hydrotalcite or boehmite nanoparticles have been prepared through melt mixing, aiming at evaluating the effect of the introduction of nanoparticles having different aspect ratios and morphologies on the rheological properties of the polymer matrix. Furthermore, the influence of the temperature on the viscoelastic response of the PEG/modified hydrotalcites nanocomposites was thoroughly investigated

Achados otoneurológicos em um caso de miopatia inflamatória Otoneurological findings in an inflammatory myopathy case

TEMA: a polimiosite é uma enfermidade sistêmica idiopática caracterizada por um processo inflamatório não supurativo que acomete a musculatura esquelética e manifesta-se clinicamente por fraqueza muscular proximal e simétrica. Possui incidência variável, cerca de um caso para cada 100 mil habitantes, havendo predominância no sexo feminino. PROCEDIMENTOS: avaliou-se no Setor de Otoneurologia de uma Instituição, um paciente com diagnóstico de polimiosite, com 60 anos, do sexo feminino, que referiu dificuldade para escutar no ouvido direito, zumbido, ansiedade, insônia, dificuldade nos movimentos do pescoço e dor irradiada para ombros e braços. Foram realizados os seguintes procedimentos: anamnese, inspeção otológica, avaliação audiológica e vestibular. RESULTADOS: a) na avaliação audiológica apresentou, perda auditiva neurossensorial de grau moderado na orelha direita e limiares auditivos dentro dos padrões de normalidade na orelha esquerda; b) na imitanciometria apresentou, curva timpanométrica do tipo "A" e presença dos reflexos estapedianos bilateralmente; c) no exame vestibular observou-se, nistagmo semi-espontâneo do tipo múltiplo e ausência do efeito inibidor da fixação ocular. CONCLUSÃO: observou-se alteração nos exames realizados, principalmente, no exame labiríntico que demonstrou a importância de sua realização e a sensibilidade na captação de alteração que sugeriu envolvimento do sistema nervoso central contribuindo dessa forma, para uma intervenção e acompanhamento terapêutico mais rápido e eficaz.BACKGROUND: polymyositis is an idiopathic systematic disease characterized by a non-suppurative inflammatory process which attacks the skeletal musculature and manifests itself clinically by proximal and symmetrical muscular debility. It shows a variable incidence, approximately one in every hundred thousand inhabitants, predominately in females. PROCEDURES: a patient, 60 years, female and diagnosed with polymyositis was evaluated in the Otoneurology Sector of an Institution, referred having hearing difficulties in the right ear, tinnitus, anxiety, insomnia, difficulties in neck movement and shoulders and arms disseminated pain. The following procedures were carried out: anamnesis, otological inspection, audiological evaluation and vestibular exam. RESULTS: a) in the audiological evaluation there was sensorineural hearing loss from moderate degrees in the right ear and normal hearing thresholds in the left ear; b) in the imitanciometry there was a type "A" tympanometric curve and the presence of the stapedial reflexes, bilaterally; c) in the vestibular exam, semi-spontaneous multiple nystagmus and an absence of the inhibiting effect for ocular fixation were observed. CONCLUSION: alterations were observed in the accomplished exams, mainly in the vestibular exam, which demonstrated the importance for being carried out; and the sensitivity in the acquisition of the alteration which suggested an involvement of the central nervous system, contributing, thus, to a faster and more effective intervention and therapeutic accompaniment