Propriedades térmicas, mecânicas e de barreira de poli(etileno-co-acetato de vinila) com bentonita modificada visando aplicação em filmes para embalagens alimentícias

Orientador : Prof. Dr. Ronilson Vasconcelos BarbosaCo-orientadora : Profª Drª Juliana Regina Kloss WeberTese (doutorado) - Universidade Federal do Paraná, Setor de Ciências Exatas, Programa de Pós-Graduação em Química. Defesa: Curitiba, 19/12/2014Inclui referências : f. 179-193Resumo: Uma das principais propriedades requeridas aos polímeros que são aplicados em embalagens alimentícias é a barreira física a gases e vapor d'água. Os polímeros com estas características ou modificados para este fim, geralmente, apresentam a inconveniência do alto custo e a necessidade de equipamentos de processamento mais complexos. Nesse contexto, o interesse no emprego e na produção de materiais com cargas orgânicas e inorgânicas com dimensões nanométricas têm-se tornado uma tendência. Em especial, as argilas organofílicas apresentam características favoráveis à formação de materiais poliméricos com boa propriedade de barreira, além de em alguns casos também conferir resistência mecânica e térmica. Diante do exposto, o presente trabalho consiste no estudo das propriedades térmicas, mecânicas e morfológicas do poli(etileno-co-acetato de vinila) (EVA) com bentonita modificada visando aplicação em filmes para embalagens alimentícias. As bentonitas naturais foram caracterizadas, antes e após a modificação química com os surfactantes AMS-32TM e brometo de cetiltrimetilamônio, por determinação da capacidade de troca iônica, espectroscopia na região do infravermelho com transformada de Fourier, difração de raios X, capacidade de inchamento, espectrometria de fluorescência de raios X e termogravimetria. As argilas naturais e organofílicas foram adicionadas ao EVA através da técnica melt blending, em extrusora monorrosca ou dupla rosca e a caracterização foi através da difração de raios X, microscopia eletrônica de varredura e/ou transmissão, comportamento térmico (calorimetria exploratória diferencial e termogravimetria), ensaio mecânico de tração e permeação a vapor d'água. Em relação às argilas, o perfil estrutural e químico das duas bentonitas foram muito semelhantes, visto pelos resultados de difração de raios X, por espectroscopia na região do infravermelho e fluorescência de raios X. Ambas apresentaram boa capacidade de troca iônica e inchamento, tornando-as compatíveis com o processo de organofilização. Os resultados das composições obtidas pela extrusora monorrosca indicaram uniformidade nas condições de preparo, indiferente da origem e da quantidade de bentonita ou de argila organofílica adicionada. Com relação às composições obtidas na extrusora dupla rosca, estas também apresentaram uniformidade nas condições de preparo, mas algumas apontaram a tendência à intercalação do polímero à bentonita natural e as argilas organofílicas, possivelmente em função do teor destas argilas e do tipo do modificador. Este fato foi verificado principalmente pelas imagens de microscopia eletrônica de transmissão. Sendo assim, diante de todos os resultados apresentados, a proposta de preparar um material com finalidade a barreira a vapor d'água, visando aplicação em embalagens alimentícias foi atingido, a partir de um filme de poli(etileno-co-acetato de vinila) contendo uma argila organofílica isento de sal de amônio. Sendo, portanto, a composição EVA/Vulgel-AM 1,5d apresentou propriedades e características satisfatórias para justificar o êxito de um material, tornando-o uma alternativa relevante para a área de estudo. Palavras-chave: poli(etileno-co-acetato de vinila); argilas organofílicas; embalagens alimentícias; barreira a vapor d'água.Abstract: One of the main properties required for polymers that are used in food packaging is a physical barrier to gases and water vapor. Polymers having these characteristics or modified for this purpose, generally have the inconvenience of high cost and the need for more complex processing equipment. In this context, the interest in employment and production of materials with organic and inorganic fillers with nanometric dimensions has become a trend. In particular, organoclays have favorable characteristics to the formation of polymeric materials with good barrier property, and in some cases also check mechanical and thermal resistance. Given the above, the present work is the study of thermal, mechanical and morphological of poly(ethylene-co-vinyl acetate) (EVA) with modified bentonite order application in films for food packaging. The natural bentonite were characterized before and after chemical modification with AMS-32TM cetyltrimethylammonium bromide surfactant by determination of ion exchange capacity, Fourier transform infrared spectroscopy, X-ray diffraction, swelling capacity, X-ray fluorescence spectroscopy and thermogravimetric analysis. Natural and organoclays were added to the EVA by melt blending technique in single or twin screw extruder and the characterization was by X-ray diffraction, scanning electron microscopy and transmission, thermal behavior (differential scanning calorimetry and thermogravimetry), mechanical tests and the water vapor permeation. In relation to clays, both structural and chemical profiles were very similar as the results of X-ray diffraction, infrared spectroscopy and X-ray fluorescence. Both offer a good capacity of ion exchange and swelling, making them compatible with organophilization process. The results of the compositions obtained by the single screw extruder indicated uniformity in the preparation conditions, regardless of the origin and quantity of bentonite or added organoclay. With respect to the compositions obtained in the twin screw extruder, these also showed uniformity in the preparation conditions, although some of them showed tendency to intercalation the polymer natural bentonite and organoclays, possibly due to the content of these clays and type of modifier. This fact was verified mainly by transmission electron microscopy images. So, the proposal to prepare a material with purpose barrier of water vapor, order application in food packaging was achieved from a poly(ethylene-co-vinyl acetate) film containing a free organoclay ammonium salt. It is, therefore, the EVA/Vulgel AM-1,5d composition showed satisfactory characteristic properties to justify the success of a material, making it an important alternative for the study area. Keywords: poly(ethylene-co-vinyl acetate); organoclays; food packaging; barrier water vapor

Controladores de rastreamento de ângulo de esterço e velocidade longitudinal de um veículo inclinável de três rodas

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia de Automação e Sistemas, Florianópolis, 2016.Este trabalho trata o problema de controle de rastreamento do ângulo de esterço e velocidade longitudinal desejados pelo condutor de um veículo inclinável de 3 rodas, enquanto mantém o ângulo de inclinação dentro de uma margem de segurança pré-estabelecida de modo a alcançar uma condução segura e fácil em malha-fechada. A idéia principal é projetar controladores que forcem o ângulo de inclinação e a velocidade longitudinal do veículo a rastrearem trajetórias de referências adequadas, onde a trajetória de referência para o ângulo de inclinação evolui dentro de uma margem de segurança pré-estabelecida. A prática comum utilizada na literatura é determinar a estrutura do controlador com base em modelos aproximados de ordem reduzida do veículo. No presente trabalho, serão projetados controladores lineares e não-lineares para tal problema de rastreamento diretamente em um modelo de um protótipo de um veículo inclinável de 3 rodas com 9-GL (graus de liberdade). Seis diferentes metodologias são usadas: controladores PID, Regulador Quadrático Linear (LQR), realimentação linearizante, controle por modos deslizantes de Slotine, Controle Vetorial Unitário (UVC) de Utkin, e uma extensão do UVC proposta recentemente. Os resultados de simulação comparam os desempenhos destes controladores sob condições nominais, assim como sob perturbações de ventos externos e incertezas paramétricas de massa e altura do centro de massa do veículo.Abstract : This works treats the control problem of tracking the steering angle and longitudinal velocity desired by the driver of a tilting 3-wheeled vehicle, while keeping its tilt angle within a pre-established safety margin, so as to achieve safe and easy driving in closed-loop. The key idea is to design controllers that force the tilt angle and the longitudinal velocity of the vehicle to track adequate reference trajectories, where the reference trajectory for the tilt angle evolves within a pre-established safety margin. A common practice in the literature is to determine the controller structure based upon reduced order approximate models of the vehicle. In the present work, one designs linear and nonlinear controllers for such tracking problem directly on a 9-DOF model of a prototype of a tilting 3-wheeled vehicle. Six different approaches are used: PID controllers, Linear Quadratic Regulator (LQR), feedback linearization, sliding mode control of Slotine, Unity Vector Control (UVC) of Utkin, and a recently proposed extension of UVC. The simulation results compare the performance of these controllers under nominal conditions, as well as under disturbances of the external wind and parametric uncertainties on the mass and center of mass height of the vehicle

Electrophysiological features of familial amyloid polyneuropathy in endemic area

The process of deterioration of peripheral nerve function in familial amyloid polyneuropathy (FAP) with amyloidogenic transthyretin (ATTR) Val30Met has not been systematically evaluated hitherto. We performed nerve conduction studies in 69 patients with FAP with ATTR Val30Met from one of the endemic areas in Japan. Sensory conduction velocity (SCV), motor conduction velocity (MCV), the size of the compound muscle action potential (CMAP) and distal latency (DL) were measured in the ulnar and tibial nerves. SCV was evaluated using the orthodromic method with needle recording electrodes. These electrophysiological parameters were compared with clinical stage of FAP and duration of neuropathy. When subjects noted minimal neuropathic symptoms only in the feet, motor and sensory nerve function in both the hands and feet had already been disturbed. Sensory nerve action potential on the foot disappeared more rapidly than CMAP. CMAP on foot muscle rapidly decreased during the initial 2 years and completely disappeared within 10 years. The duration of illness and deterioration parameters (CMAP of the abductor digiti minimi muscle, MCV and SCV of the ulnar nerve and DL of both ulnar and tibial nerves) were linearly correlated. CMAP was the most sensitive and reliable parameter to evaluate motor nerve degeneration in FAP.</.ArticleAMYLOID-JOURNAL OF PROTEIN FOLDING DISORDERS. 18(1):10-18 (2011)journal articl

IDE Gene Polymorphism Influences on BPSD in Mild Dementia of Alzheimer's Type

Insulin degrading enzyme (IDE) degrades amyloid β (Aβ), which may inhibit the accumulation of Aβ in a brain affected with dementia of Alzheimer's type (DAT). A decrease in the activity of IDE results in changes in glucose utilization in the brain, which could affect the cognitive and psychiatric symptoms of DAT. We investigated a possible association of IDE gene polymorphism and the behavioral and psychological symptoms of dementia (BPSD) in mild DAT. The genotyping for IDE and apolipoprotein E (ApoE) was determined in 207 patients with mild DAT and 215 controls. The occurrence of BPSD was demonstrated using the Behavioral Pathology in Alzheimer's Disease Rating Scale (BEHAVE-AD). IDE gene polymorphism is unlikely to play a substantial role in conferring susceptibility to DAT, but it may be involved in the development of affective disturbance through the course of mild DAT, regardless of the presence of an ApoE ε4 allele. The present data could be the result of a small sample size. Further investigations using larger samples are thus required to clarify the correlation between IDE gene polymorphism, susceptibility to DAT, and emergence of BPSD

High temperature tensile behavior of zirconia ceramics under DC current

These Flash sintering phenomena, which occurs by applying DC current directly to ceramic powder compacts, has been the subject of many paper of ceramic sintering. This is because the flash event can succeed to lower the sintering temperature/time of several ceramic powders. On the other hand, Conrad and his colleagues examined the effect of electric fields on the high temperature tensile properties of 3Y-TZP and confirmed that the fields can lower the tensile flow stresses of 3Y-TZP enough to attain superplasticity. The enhanced deformation was explained by suppressed grain growth due to the electric bias effect. However, the mechanism/phenomena of the flash event are still unclear. In order to clarify the effect of electric current on high temperature deformation, therefore, the present study was carried out to examine the tensile behavior of polycrystalline zirconia ceramics under the several temperature and electric field/current conditions. By applying the DC electric power higher than a critical value Ec, the flash event similar to that of powder sintering occurs even in dense zirconia ceramics. At around 1000 °C, for example, the Ec value is about 100 - 200 mW/mm3, which is slightly larger than those reported in the powder compacts. For lower than Ec, the applied electric current increases sample temperature depending on the applied value, but does not enhance the rate of deformation. For higher than Ec, on the other hand, the electric current enhances the rate of the deformation to about several times as compared with that of without current conditions. The enhanced deformation cannot be interpreted only by the increment of sample temperatures and is likely to occur by the flash event. After the deformation under the electric current conditions, the tested sample shows slight gray color even under air condition. This suggests that the enhanced deformation would be related to oxygen vacancy formation. In the presentation, we will discuss the detailed current effect obtained at wide range testing conditions

Caldesmon suppresses cancer cell invasion by regulating podosome/invadopodium formation

AbstractThe podosome and invadopodium are dynamic cell-adhesion structures that degrade the extracellular matrix (ECM) and promote cell invasion. We recently reported that the actin-binding protein caldesmon is a pivotal regulator of podosome formation. Here, we analyzed the caldesmon’s involvement in podosome/invadopodium-mediated invasion by transformed and cancer cells. The ectopic expression of caldesmon reduced the number of podosomes/invadopodia and decreased the ECM degradation activity, resulting in the suppression of cell invasion. Conversely, the depletion of caldesmon facilitated the formation of podosomes/invadopodia and cell invasion. Taken together, our results indicate that caldesmon acts as a potent repressor of cancer cell invasion

Apoio multicritério na priorização de recursos em trabalhos cartográficos: um estudo em bases de dados: Multicriteria support in the prioritization of resources in cartographic works: a study in databases

O objetivo do presente trabalho é evidenciar a utilidade dos métodos multicritério na priorização de recursos na produção de informações cartográficas. Para tal foi realizada uma revisão sistemática da literatura em bases de dados científicas no período de 2007 a 2022. Foram observados na literatura conceitos e procedimentos relacionados a caracterização da produção científica sobre priorização e métodos de apoio multicritério à decisão, examinando as contribuições de diferentes países, periódicos, autores e tendências de pesquisas. A análise dos trabalhos demonstrou uma significativa preponderância dos métodos multicritério AHP e MCDA-C

The safety of transcranial magnetic stimulation with deep brain stimulation instruments

Objectives: Transcranial magnetic stimulation (TMS) has been employed in patients with an implanted deep brain Stimulation (DBS) device. We investigated the safety of TMS using Simulation models with an implanted DBS device. Methods: The DBS lead was inserted into plastic phantoms filled with dilute gelatin showing impedance similar to that of human brain. TMS was performed with three different types of magnetic coil. During TMS (I) electrode movement, (2) temperature change around the lead, and (3) TMS-induced current in various Situations were observed. The amplitude and area of each evoked current were measured to calculate charge density of the evoked current. Results: There was no movement or temperature increase during 0.2 Hz repetitive TMS with 100% stimulus intensity for 1 h. The size of evoked current linearly increased with TMS intensity. The maximum charge density exceeded the safety limit of 30 mu C/cm(2)/phase during Stimulation above the loops of the lead with intensity over 50% using a figure-eight coil. Conclusions: Strong TMS on the looped DBS leads should not be administered to avoid electrical tissue injury. Subcutaneous lead position should be paid enough attention for forthcoming Situations during surgery.ArticlePARKINSONISM & RELATED DISORDERS. 16(2):127-131 (2010)journal articl

A Case of Acute Superior Mesenteric Artery Embolism with Severe Ischemic Liver Injury Successfully Treated by Endovascular Treatment

We describe an interesting clinical course of a patient who developed severe ischemic liver injury due to acute embolism of the superior mesenteric artery (SMA) and celiac artery. A 70-year-old man was hospitalized for abdominal pain and diarrhea. Abdominal computed tomography demonstrated a variant common hepatic artery arising from the SMA and multiple thromboembolic occlusions of visceral arteries, including the SMA and celiac artery. Laboratory data showed markedly elevated hepatic enzymes, which increased after admission despite the initiation of systemic anticoagulant and thrombolytic therapy. The patient was successfully treated by endovascular recanalization of the SMA occlusion via transcatheter embolus aspiration, thrombolysis, balloon angioplasty, and stent placement. Severe ischemic liver injury may occur in the setting of synchronous embolism of the SMA and celiac artery, and these phenomena may have a critical impact on the choice of treatment strategies and prognosis. Endovascular treatment appears to an effective treatment option