944 resultados para Rugosidade superficial


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Until 2008, Macedonia was leading the process of EU and NATO integration, and (after Croatia) was the fastest-reforming Western Balkan country. However, since Macedonia’s negotiations on joining the EU and NATO were blocked, in connection with its dispute with Greece, the Macedonian government has moved away from a policy of reform towards reinforcing its autocratic system and consolidating society behind nationalist slogans. Also the EU, which had hitherto been the driving force behind the changes, has due to its internal crises been paying little attention to violations of democratic standards in the Republic of Macedonia, tensions in relations between the Slavic Macedonians and the Albanian minority (which make up over 25% of the population), and the country’s permanent political domestic crises.

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Dissertação para obtenção do grau de Mestre no Instituto Superior de Ciências da Saúde Egas Moniz

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O objetivo deste estudo foi avaliar a topografia de superfície dos fios estéticos, antes e após teste de deflexão. A amostra foi composta por 70 corpos de prova de fios 0,014 redondos, sendo 10 de cada uma das marcas comerciais avaliadas: Orthocosmetic Elastinol (Masel), Flexy Super Elastic Esthetic (Orthometric), InVu (TP Orthodontics) e ProForm Nitanium (Ortho Organizers) fios de NiTi revestidos por Teflon®; Optis (TP Orthodontics) fio de resina reforçado por fibra de vidro ou FRP; Niticosmetic (Tecnident) fio de NiTi revestido por resina epoxídica; e Nitinol SE (3M Unitek) fio de NiTi superelástico, usado para controle. A topografia de superfície de cada fio foi avaliada por rugosímetro e por microscópio óptico, antes e após ser submetido a ensaio de deflexão, no lado em que a força foi aplicada e no lado oposto a este. Cada fio foi defletido em 3,1mm, a uma velocidade de 1mm/min, com célula de carga de 5N a 36⁰C + 1⁰C. A análise de variância a três critérios (p<0,05) mostrou diferença significante entre os fios e o teste de Tukey mostrou que o fio Optis (TP Orthodontics) apresentou aumento nos parâmetros de rugosidade Ra, Rt e Rz, após a deflexão. O fio Niticosmetic (Tecnident) apresentou aumento na rugosidade média (Ra). O fio InVu (TP Orthodontics) foi o único que mostrou aumento na rugosidade no lado em que a força foi aplicada. A análise visual por meio de microscopia óptica revelou alterações na superfície em todos os fios estéticos após o teste de deflexão, desde delaminações do revestimento, observadas nos fios Orthocosmetic Elastinol e InVu, riscos permanentes na superfície, como visto nos fios Flexy Super Elastic Esthetic, Niticosmetic e ProForm Nitanium, e até mesmo fratura incompleta, no fio Optis. Concluiu-se que o fio Niticosmetic apresentou topografia de superfície similar ao fio metálico, e os demais fios estéticos apresentaram maior rugosidade e alterações visuaisna superfície.

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The entorhinal cortex (EC) controls hippocampal input and output, playing major roles in memory and spatial navigation. Different layers of the EC subserve different functions and a number of studies have compared properties of neurones across layers. We have studied synaptic inhibition and excitation in EC neurones, and we have previously compared spontaneous synaptic release of glutamate and GABA using patch clamp recordings of synaptic currents in principal neurones of layers II (L2) and V (L5). Here, we add comparative studies in layer III (L3). Such studies essentially look at neuronal activity from a presynaptic viewpoint. To correlate this with the postsynaptic consequences of spontaneous transmitter release, we have determined global postsynaptic conductances mediated by the two transmitters, using a method to estimate conductances from membrane potential fluctuations. We have previously presented some of this data for L3 and now extend to L2 and L5. Inhibition dominates excitation in all layers but the ratio follows a clear rank order (highest to lowest) of L2>L3>L5. The variance of the background conductances was markedly higher for excitation and inhibition in L2 compared to L3 or L5. We also show that induction of synchronized network epileptiform activity by blockade of GABA inhibition reveals a relative reluctance of L2 to participate in such activity. This was associated with maintenance of a dominant background inhibition in L2, whereas in L3 and L5 the absolute level of inhibition fell below that of excitation, coincident with the appearance of synchronized discharges. Further experiments identified potential roles for competition for bicuculline by ambient GABA at the GABAA receptor, and strychnine-sensitive glycine receptors in residual inhibition in L2. We discuss our results in terms of control of excitability in neuronal subpopulations of EC neurones and what these may suggest for their functional roles. © 2014 Greenhill et al.

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The diatomite is a natural material that has numerous applications due to changes in their physical and chemical properties after processing. It is currently used in the industry as a sound insulator , filter aid and industrial load . The filter material shall be inert chemical composition , which will diatomite confers a high commercial value and performance not found in other particulate materials , for this application. The diatomite surface undergoes changes after thermal treatment at high temperatures , from 800ºC , with properties that enable its application in the food , beverage , pharmaceutical , cosmetic and textiles . In this work , we developed a study on thermal treatment on natural diatomite to adapt their properties to the application as a filter aid . The heat treatments were performed in an open oven at temperatures of 800ºC , 1000ºC and 1200ºC for a time of 24 hours. Reagents were added in the constitution of the samples analyzed. The reagents used were sodium carbonate (Na2CO3 ) and sodium chloride (NaCl) . The samples were characterized by x - ray diffraction , x -ray fluorescence , scanning electron microscopy , analysis and particle size distribution , specific surface area by the BET method , and pore volume by BJH method. The results showed a reduction in porosity of the material as well as a significant increase in specific surface area after heat treatment and the reactants in the ratio of 3 wt%. The diatomaceous earth , after heat treatment , undergone changes in its coloration , varying in white, cream and beige , which directly interferes with the speed of filtration materials process. All results obtained before and after heat treatment of the material with the values obtained for samples already used industrially , Brazilian and American industry , which were characterized using the same test methods performed with the samples in the study were compared and showed promising efficiency when material studied in the region of Punaú - RN , after processing , reagent addition and heat treatment, as an element in the composition of filter .

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Adsorption is a process that has become indispensable due to pollution caused by industrial activity. More economically viable adsorbents are being tested to replace the high cost of materials used. The clays can be used as adsorbents and are low cost materials, natural properties feasible for the application in the adsorption process, structural modifications are performed with ease promoting selective adsorption in these materials. The objective of this study was to synthesize and characterize adsorbents used in the adsorption of organic compounds. The adsorbents were characterized by the techniques of XRD, SEM, FTIR and TG. The results show that the studied materials have affinity to organic compounds and can be applied as adsorbents. The materials studied are viable and can be applied in the treatment of effluents contaminated in industrial scale.

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Urinary tract infections (UTIs) are typically caused by bacteria that colonize different regions of the urinary tract, mainly the bladder and the kidney. Approximately 25% of women that suffer from UTIs experience a recurrent infection within 6 months of the initial bout, making UTIs a serious economic burden resulting in more than 10 million hospital visits and $3.5 billion in healthcare costs in the United States alone. Type-1 fimbriated Uropathogenic E. coli (UPEC) is the major causative agent of UTIs, accounting for almost 90 % of bacterial UTIs. The unique ability of UPEC to bind and invade the superficial bladder epithelium allows the bacteria to persist inside epithelial niches and survive antibiotic treatment. Persistent, intracellular UPEC are retained in the bladder epithelium for long periods, making them a source of recurrent UTIs. Hence, the ability of UPEC to persist in the bladder is a matter of major health and economic concern, making studies exploring the underlying mechanism of UPEC persistence highly relevant.

In my thesis, I will describe how intracellular Uropathogenic E.coli (UPEC) evade host defense mechanisms in the superficial bladder epithelium. I will also describe some of the unique traits of persistent UPEC and explore strategies to induce their clearance from the bladder. I have discovered that the UPEC virulence factor Alpha-hemolysin (HlyA) plays a key role in the survival and persistence of UPEC in the superficial bladder epithelium. In-vitro and in-vivo studies comparing intracellular survival of wild type (WT) and hemolysin deficient UPEC suggested that HlyA is vital for UPEC persistence in the superficial bladder epithelium. Further in-vitro studies revealed that hemolysin helped UPEC persist intracellularly by evading the bacterial expulsion actions of the bladder cells and remarkably, this virulence factor also helped bacteria avoid t degradation in lysosomes.

To elucidate the mechanistic basis for how hemolysin promotes UPEC persistence in the urothelium, we initially focused on how hemolysin facilitates the evasion of UPEC expulsion from bladder cells. We found that upon entry, UPEC were encased in “exocytic vesicles” but as a result of HlyA expression these bacteria escaped these vesicles and entered the cytosol. Consequently, these bacteria were able to avoid expulsion by the cellular export machinery.

Since bacteria found in the cytosol of host cells are typically recognized by the cellular autophagy pathway and transported to the lysosomes where they are degraded, we explored why this was not the case here. We observed that although cytosolic HlyA expressing UPEC were recognized and encased by the autophagy system and transported to lysosomes, the bacteria appeared to avoid degradation in these normally degradative compartments. A closer examination of the bacteria containing lysosomes revealed that they lacked V-ATPase. V-ATPase is a well-known proton pump essential for the acidification of mammalian intracellular degradative compartments, allowing for the proper functioning of degradative proteases. The absence of V-ATPase appeared to be due to hemolysin mediated alteration of the bladder cell F-actin network. From these studies, it is clear that UPEC hemolysin facilitates UPEC persistence in the superficial bladder epithelium by helping bacteria avoid expulsion by the exocytic machinery of the cell and at the same time enabling the bacteria avoid degradation when the bacteria are shuttled into the lysosomes.

Interestingly even though UPEC appear to avoid elimination from the bladder cell their ability to multiple in bladder cells seem limited.. Indeed, our in-vitro and in-vivo experiments reveal that UPEC survive in superficial bladder epithelium for extended periods of time without a significantly change in CFU numbers. Indeed, we observed these bacteria appeared quiescent in nature. This observation was supported by the observation that UPEC genetically unable to enter a quiescence phase exhibited limited ability to persist in bladder cells in vitro and in vivo, in the mouse bladder.

The studies elucidated in this thesis reveal how UPEC toxin, Alpha-hemolysin plays a significant role in promoting UPEC persistence via the modulation of the vesicular compartmentalization of UPEC at two different stages of the infection in the superficial bladder epithelium. These results highlight the importance of UPEC Alpha-hemolysin as an essential determinant of UPEC persistence in the urinary bladder.

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Spectral albedo has been measured at Dome C since December 2012 in the visible and near infrared (400 - 1050 nm) at sub-hourly resolution using a home-made spectral radiometer. Superficial specific surface area (SSA) has been estimated by fitting the observed albedo spectra to the analytical Asymptotic Approximation Radiative Transfer theory (AART). The dataset includes fully-calibrated albedo and SSA that pass several quality checks as described in the companion article. Only data for solar zenith angles less than 75° have been included, which theoretically spans the period October-March. In addition, to correct for residual errors still affecting data after the calibration, especially at the solar zenith angles higher than 60°, we produced a higher quality albedo time-series as follows: In the SSA estimation process described in the companion paper, a scaling coefficient A between the observed albedo and the theoretical model predictions was introduced to cope with these errors. This coefficient thus provides a first order estimate of the residual error. By dividing the albedo by this coefficient, we produced the "scaled fully-calibrated albedo". We strongly recommend to use the latter for most applications because it generally remains in the physical range 0-1. The former albedo is provided for reference to the companion paper and because it does not depend on the SSA estimation process and its underlying assumptions.