Evaluation of the use of PetrifilmTM EB count plates for the enumeration of Enterobacteriaceae in poultry samples.

Um teste rápido, que apresente o resultado em curto período de tempo, que seja simples, sensível para detectar baixos níveis de micro-organismos, preciso e que não seja caro, seria o mais adequado para a rotina laboratorial da indústria de alimentos ou mesmo para os laboratórios de Saúde Pública. Um dos métodos alternativos prontos para o uso, comercialmente disponíveis no mercado, são as placas PetrifilmTM. O objetivo deste estudo foi avaliar se há diferença estatística significativa entre o método convencional - empregando o ágar vermelho violeta bile glicose ? e o método alternativo, PetrifilmTM EB (3M Company), para a enumeração de Enterobacteriaceae em carcaças de frango.

CHARACTERIZATION OF THERMAL AND MECHANICAL PROPERTIES OF POLYPROPYLENE–BASED COMPOSITES FOR FUEL CELL BIPOLAR PLATES AND DEVELOPMENT OF EDUCATIONAL TOOLS IN HYDROGEN AND FUEL CELL TECHNOLOGIES

In this project we developed conductive thermoplastic resins by adding varying amounts of three different carbon fillers: carbon black (CB), synthetic graphite (SG) and multi–walled carbon nanotubes (CNT) to a polypropylene matrix for application as fuel cell bipolar plates. This component of fuel cells provides mechanical support to the stack, circulates the gases that participate in the electrochemical reaction within the fuel cell and allows for removal of the excess heat from the system. The materials fabricated in this work were tested to determine their mechanical and thermal properties. These materials were produced by adding varying amounts of single carbon fillers to a polypropylene matrix (2.5 to 15 wt.% Ketjenblack EC-600 JD carbon black, 10 to 80 wt.% Asbury Carbons’ Thermocarb TC-300 synthetic graphite, and 2.5 to 15 wt.% of Hyperion Catalysis International’s FIBRILTM multi-walled carbon nanotubes) In addition, composite materials containing combinations of these three fillers were produced. The thermal conductivity results showed an increase in both through–plane and in–plane thermal conductivities, with the largest increase observed for synthetic graphite. The Department of Energy (DOE) had previously set a thermal conductivity goal of 20 W/m·K, which was surpassed by formulations containing 75 wt.% and 80 wt.% SG, yielding in–plane thermal conductivity values of 24.4 W/m·K and 33.6 W/m·K, respectively. In addition, composites containing 2.5 wt.% CB, 65 wt.% SG, and 6 wt.% CNT in PP had an in–plane thermal conductivity of 37 W/m·K. Flexural and tensile tests were conducted. All composite formulations exceeded the flexural strength target of 25 MPa set by DOE. The tensile and flexural modulus of the composites increased with higher concentration of carbon fillers. Carbon black and synthetic graphite caused a decrease in the tensile and flexural strengths of the composites. However, carbon nanotubes increased the composite tensile and flexural strengths. Mathematical models were applied to estimate through–plane and in–plane thermal conductivities of single and multiple filler formulations, and tensile modulus of single–filler formulations. For thermal conductivity, Nielsen’s model yielded accurate thermal conductivity values when compared to experimental results obtained through the Flash method. For prediction of tensile modulus Nielsen’s model yielded the smallest error between the predicted and experimental values. The second part of this project consisted of the development of a curriculum in Fuel Cell and Hydrogen Technologies to address different educational barriers identified by the Department of Energy. By the creation of new courses and enterprise programs in the areas of fuel cells and the use of hydrogen as an energy carrier, we introduced engineering students to the new technologies, policies and challenges present with this alternative energy. Feedback provided by students participating in these courses and enterprise programs indicate positive acceptance of the different educational tools. Results obtained from a survey applied to students after participating in these courses showed an increase in the knowledge and awareness of energy fundamentals, which indicates the modules developed in this project are effective in introducing students to alternative energy sources.

Dynamic mechanical-thermal, microstructural and mechanical analysis of ultra-light polymer-metal composites: influence of forming

A really particular and innovative metal-polymer sandwich material is Hybrix. Hybrix is a product developed and manufactured by Lamera AB, Gothenburg, Sweden. This innovative hybrid material is composed by two relatively thin metal layers if compared to the core thickness. The most used metals are aluminum and stainless steel and are separated by a core of nylon fibres oriented perpendicularly to the metal plates. The core is then completed by adhesive layers applied at the PA66-metal interface that once cured maintain the nylon fibres in position. This special material is very light and formable. Moreover Hybrix, depending on the specific metal which is used, can achieve a good corrosion resistance and it can be cut and punched easily. Hybrix architecture itself provides extremely good bending stiffness, damping properties, insulation capability, etc., which again, of course, change in magnitude depending in the metal alloy which is used, its thickness and core thickness. For these reasons nowadays it shows potential for all the applications which have the above mentioned characteristic as a requirement. Finally Hybrix can be processed with tools used in regular metal sheet industry and can be handled as solid metal sheets. In this master thesis project, pre-formed parts of Hybrix were studied and characterized. Previous work on Hybrix was focused on analyze its market potential and different adhesive to be used in the core. All the tests were carried out on flat unformed specimens. However, in order to have a complete description of this material also the effect of the forming process must be taken into account. Thus the main activities of the present master thesis are the following: Dynamic Mechanical-Thermal Analysis (DMTA) on unformed Hybrix samples of different thickness and on pre-strained Hybrix samples, pure epoxy adhesive samples analysis and finally moisture effects evaluation on Hybrix composite structure.

Vortex evolution in the wake of accelerating low-aspect-ratio plates and three-dimensional bodies of revolution

To find examples of effecient locomotion and manoeuvrability, one need only turn to the elegant solutions natural flyers and swimmers have converged upon. This dissertation is specifically motivated by processes of evolutionary convergence, which have led to the propulsors and body shapes in nature that exhibit strong geometric collapse over diverse scales. These body features are abstracted in the studies presented herein using low-aspect-ratio at plates and a three-dimensional body of revolution (a sphere). The highly-separated vortical wakes that develop during accelerations are systematically characterized as a function of planform shape, aspect ratio, Reynolds number, and initial boundary conditions. To this end, force measurements and time-resolved (planar) particle image velocimetry have been used throughout to quantify the instantaneous forces and vortex evolution in the wake of the bluff bodies. During rectilinear motions, the wake development for the flat plates is primarily dependent on plate aspect ratio, with edge discontinuities and curvature playing only a secondary role. Furthermore, the axisymmetric case, i.e. the circular plate, shows strong sensitivity to Reynolds number, while this sensitivity quickly diminishes with increasing aspect ratio. For rotational motions, global insensitivity to plate aspect ratio has been observed. For the sphere, it has been shown that accelerations play an important role in the mitigation of flow separation. These results - expounded upon in this dissertation - have begun to shed light on the specific vortex dynamics that may be coopted by flying and swimming species of all shapes and sizes towards efficient locomotion.

Phase-field analysis of finite-strain plates and shells including element subdivision

With the theme of fracture of finite-strain plates and shells based on a phase-field model of crack regularization, we introduce a new staggered algorithm for elastic and elasto-plastic materials. To account for correct fracture behavior in bending, two independent phase-fields are used, corresponding to the lower and upper faces of the shell. This is shown to provide a realistic behavior in bending-dominated problems, here illustrated in classical beam and plate problems. Finite strain behavior for both elastic and elasto-plastic constitutive laws is made compatible with the phase-field model by use of a consistent updated-Lagrangian algorithm. To guarantee sufficient resolution in the definition of the crack paths, a local remeshing algorithm based on the phase- field values at the lower and upper shell faces is introduced. In this local remeshing algorithm, two stages are used: edge-based element subdivision and node repositioning. Five representative numerical examples are shown, consisting of a bi-clamped beam, two versions of a square plate, the Keesecker pressurized cylinder problem, the Hexcan problem and the Muscat-Fenech and Atkins plate. All problems were successfully solved and the proposed solution was found to be robust and efficient.

Vibro-acoustic analysis of additively manufactured acoustic metamaterials

In the last decade it emerged the interest in new types of acoustic insulating materials, called acoustic metamaterials. These materials are composed by a host and inclusions and are arranged periodically or non-periodically in sub-wavelength elements called meta-atoms. Their inclusions and internal geometries can be manipulated to tailor the acoustic properties, reducing weight, and increasing at the same time their efficiency. Thanks to the high absorbing characteristics that they can achieve, their usage is of particularly interest as material of the core in sandwich panels of aerospace structures to reduce vibrations and noise inside passengers aircraft’s cabin. In addition, since the low frequency signals are difficult to be damped with conventional materials, their usage can guarantee a high transmission loss at low frequencies, obtaining a positive benefit on passengers’ comfort. The performances and efficiency of these materials are enhanced thanks to the new additive manufacturing techniques opposed to the conventional ones uncapable to pro- duce such complex internal geometries. The aim of this work is to study, produce and redesign micro-perforated sandwich panels of a literature case study to achieve high performances in the low frequency range, e.g., below 2000 Hz. Some geometrical parameters, such as perforation ratio and diameter of holes, were considered to realize different models and see the differences in the sound transmission loss. The models were produced by means of Fused Deposition Modelling using an Acrylonitrile Butadiene Styrene (ABS Plus p430) material on a commercial additive manufacturing system. Finally, the frequency response analysis was carried out with Mul2 software, based on the Carrera’s Unified Formulation (CUF) to understand the acoustic and structural properties of the material employed, analyzing the plates’ displacements and the TL results.

Computational design of a new type of sandwich cross-section for a defined solution of a tree-like column produced by wire-and-arc additive manufacturing

When it comes to designing a structure, architects and engineers want to join forces in order to create and build the most beautiful and efficient building. From finding new shapes and forms to optimizing the stability and the resistance, there is a constant link to be made between both professions. In architecture, there has always been a particular interest in creating new shapes and types of a structure inspired by many different fields, one of them being nature itself. In engineering, the selection of optimum has always dictated the way of thinking and designing structures. This mindset led through studies to the current best practices in construction. However, both disciplines were limited by the traditional manufacturing constraints at a certain point. Over the last decades, much progress was made from a technological point of view, allowing to go beyond today's manufacturing constraints. With the emergence of Wire-and-Arc Additive Manufacturing (WAAM) combined with Algorithmic-Aided Design (AAD), architects and engineers are offered new opportunities to merge architectural beauty and structural efficiency. Both technologies allow for exploring and building unusual and complex structural shapes in addition to a reduction of costs and environmental impacts. Through this study, the author wants to make use of previously mentioned technologies and assess their potential, first to design an aesthetically appreciated tree-like column with the idea of secondly proposing a new type of standardized and optimized sandwich cross-section to the construction industry. Parametric algorithms to model the dendriform column and the new sandwich cross-section are developed and presented in detail. A catalog draft of the latter and methods to establish it are then proposed and discussed. Finally, the buckling behavior of this latter is assessed considering standard steel and WAAM material properties.

Staphylococcus Aureus Enterotoxins A And B Inhibit Human And Mice Eosinophil Chemotaxis And Adhesion In Vitro.

Staphylococcus aureus aggravates the allergic eosinophilic inflammation. We hypothesized that Staphylococcus aureus-derived enterotoxins directly affect eosinophil functions. Therefore, this study investigated the effects of Staphylococcal enterotoxins A and B (SEA and SEB) on human and mice eosinophil chemotaxis and adhesion in vitro, focusing on p38 MAPK phosphorylation and intracellular Ca(2+) mobilization. Eosinophil chemotaxis was evaluated using a microchemotaxis chamber, whereas adhesion was performed in VCAM-1 and ICAM-1-coated plates. Measurement of p38 MAPK phosphorylation and intracellular Ca(2+) levels were monitored by flow cytometry and fluorogenic calcium-binding dye, respectively. Prior incubation (30 to 240 min) of human blood eosinophils with SEA (0.5 to 3 ng/ml) significantly reduced eotaxin-, PAF- and RANTES-induced chemotaxis (P<0.05). Likewise, SEB (1 ng/ml, 30 min) significantly reduced eotaxin-induced human eosinophil chemotaxis (P<0.05). The reduction of eotaxin-induced human eosinophil chemotaxis by SEA and SEB was prevented by anti-MHC monoclonal antibody (1 μg/ml). In addition, SEA and SEB nearly suppressed the eotaxin-induced human eosinophil adhesion in ICAM-1- and VCAM-1-coated plates. SEA and SEB prevented the increases of p38 MAPK phosphorylation and Ca(2+) levels in eotaxin-activated human eosinophils. In separate protocols, we evaluated the effects of SEA on chemotaxis and adhesion of eosinophils obtained from mice bone marrow. SEA (10 ng/ml) significantly reduced the eotaxin-induced chemotaxis along with cell adhesion to both ICAM-1 and VCAM-1-coated plates (P<0.05). In conclusion, the inhibition by SEA and SEB of eosinophil functions (chemotaxis and adhesion) are associated with reductions of p38 MAPK phosphorylation and intracellular Ca(2+) mobilization.

Comparative In vitro Mechanical Evaluation Of Techniques Using A 2.0 mm Locking Fixation System For Simulated Fractures Of The Mandibular Body.

To perform a comparative evaluation of the mechanical resistance of simulated fractures of the mandibular body which were repaired using different fixation techniques with two different brands of 2.0 mm locking fixation systems. Four aluminum hemimandibles with linear sectioning simulating a mandibular body fracture were used as the substrates and were fixed using the two techniques and two different brands of fixation plate. These were divided into four groups: groups I and II were fixed with one four-hole plate, with four 6 mm screws in the tension zone and one four-hole plate, with four 10 mm screws in the compression zone; and groups III and IV were fixed with one four-hole plate with four 6 mm screws in the neutral zone. Fixation plates manufactured by Tóride were used for groups I and III, and by Traumec for groups II and IV. The hemimandibles were submitted to vertical, linear load testing in an Instron 4411 servohydraulic mechanical testing unit, and the load/displacement (3 mm, 5 mm and 7 mm) and the peak loads were measured. Means and standard deviations were evaluated applying variance analysis with a significance level of 5%. The only significant difference between the brands was seen at displacements of 7 mm. Comparing the techniques, groups I and II showed higher mechanical strength than groups III and IV, as expected. For the treatment of mandibular linear body fracture, two locking plates, one in the tension zone and another in the compression zone, have a greater mechanical strength than a single locking plate in the neutral zone.

Mechanical And Photoelastic Analysis Of Four Different Fixation Methods For Mandibular Body Fractures.

The aim of the present study was to compare four methods of fixation in mandibular body fractures. Mechanical and photoelastic tests were performed using polyurethane and photoelastic resin mandibles, respectively. The study groups contained the following: (I), two miniplates of 2.0 mm; (II) one 2.0 mm plate and an Erich arch bar; (III) one 2.4 mm plate and an Erich arch bar, and (IV) one 2.0 mm plate and one 2.4 mm plate. The differences between the mean values were analyzed using Tukey's test, the Mann-Whitney test and the Bonferroni correction. Group II recorded the lowest resistance, followed by groups I, IV and III. The photoelastic test confirmed the increase of tension in group II. The 2.4 mm system board in linear mandibular body fractures provided more resistance and the use of only one 2.0 mm plate in the central area of the mandible created higher tension.

Análise epidemiológica das fraturas acetabulares

This aim of this work was to carry out an epidemiological study on acetabular fractures in the city of Campinas and surrounds, in view of the few published papers on this subject. Medical files with a diagnosis of acetabular fracture between the years 2004 and 2008 that were made available by the Medical Archiving Service of Hospital das Clínicas, State University of Campinas (UNICAMP) were analyzed by six observers. Data on patients' ages, sex, side affected by the fracture, mechanism of injury, material used for synthesis, complications of the operation, associated fractures, length of hospitalization before and after the surgery, time of total internment and number of physiotherapy sessions before and after the surgery were gathered. It was observed in this population that the left side was more affected; the mechanism of injury that most often caused this type of fracture was automobile accidents; injuries to the sciatic nerve were the commonest surgical complications; and the synthesis material most used was reconstruction plates.

Estudo inicial da degradação in vivo de poli(L-co-D,L ácido lático), sintetizado em laboratório, aplicado como prótese tibial em coelhos

The copolymer poly (L-co-D,L lactic acid), PLDLA, has gained prominence in the field of temporary prostheses due to the fact that their time of degradation is quite compatible with the requirement in the case of osseous fracture. In this work the in vivo degradation of devices from copolymer, as a system of plates and screws, used in fixation of the tibia of rabbits was studied. The devices were implanted in 15 adult rabbits, albinos, New Zealand race, and they were used as control devices of alloys of titanium (Ti-6Al-4V/ V grade). The use of copolymers, synthesized in the laboratory, was tested in the repair of fracture in rabbits'tibias, being assessed in the following times: 2 weeks, 2 months and 3 months. Morphological analysis of tissue surrounding the plate and screw system, for 2 weeks of implantation, showed the presence of osteoblasts, indicating a pre bone formation. After 2 months there was new bone formation in the region in contact with the polymer. This bone growth occurred simultaneously with the process of PLDLA degradation, invading the region where there was polymer and after 3 months there was an intense degradation of the copolymer and hence greater tissue invasion compared to 2 months which characterized bone formation in a region where the polymer degraded. The in vivo degradation study of the devices for PLDLA by means of histological evaluations during the period of consolidation of the fracture showed the efficiency of plate and screw system, and it was possible to check formation of bone tissue at the implantation site, without the presence of inflammatory reaction

Morfologia alveolar sob a perspectiva da tomografia computadorizada: definindo os limites biológicos para a movimentação dentária

INTRODUÇÃO: a tomografia computadorizada (TC) permite a visualização do osso alveolar que recobre os dentes por vestibular e lingual. OBJETIVO: o propósito deste estudo foi expor e discutir as implicações da morfologia do osso alveolar, visualizado por meio da TC, sobre o diagnóstico e plano de tratamento ortodôntico. MÉTODOS: foram descritas as evidências sobre a inter-relação entre características dentofaciais e a morfologia das tábuas ósseas vestibular e lingual, assim como evidências sobre a repercussão da movimentação ortodôntica sobre o nível e espessura dessas estruturas periodontais. RESULTADOS: pacientes adultos podem apresentar deiscências ósseas previamente ao tratamento ortodôntico, principalmente na região dos incisivos inferiores. Os pacientes com padrão de crescimento vertical parecem apresentar menor espessura das tábuas ósseas vestibular e lingual no nível do ápice dos dentes permanentes, comparados a pacientes com padrão de crescimento horizontal. O movimento dentário vestibulolingual descentraliza os dentes do rebordo alveolar e ocasiona deiscências ósseas. CONCLUSÃO: a morfologia do rebordo alveolar constitui um fator limitante para a movimentação dentária e deve ser considerada, de forma individual, na realização do plano de tratamento ortodôntico.

Reprodutibilidade das mensurações da espessura das tábuas ósseas na tomografia computadorizada Cone-Beam utilizando diferentes protocolos de aquisição de imagem

INTRODUÇÃO: quanto menor a dimensão do voxel, maior a nitidez da imagem de tomografia computadorizada Cone-Beam (TCCB), porém, maior a dose de radiação emitida. OBJETIVOS: avaliar e comparar a reprodutibilidade da mensuração da espessura das tábuas ósseas vestibular e lingual em imagens de TCCB, utilizando diferentes protocolos de aquisição de imagem com variação da dimensão do voxel. MÉTODOS: exames de TCCB foram tomados de 12 mandíbulas humanas secas, com dimensão do voxel de 0,2; 0,3 e 0,4mm, no aparelho i-CAT Cone-Beam 3-D Dental Imaging System. No software i-CAT Viewer, foi mensurada a espessura das tábuas ósseas vestibular e lingual, em um corte axial passando 12mm acima do forame mentoniano do lado direito. A reprodutibilidade intraexaminador foi avaliada por meio da aplicação do teste t pareado. Para a comparação interexaminadores, foi utilizado o teste t independente. Os resultados foram considerados com o nível de significância de 5%. RESULTADOS: observou-se uma excelente reprodutibilidade interexaminadores para os três protocolos avaliados. A reprodutibilidade intraexaminadores foi muito boa, com exceção de algumas regiões dos dentes anteriores, que mostraram diferenças estatisticamente significativas, independentemente da dimensão do voxel. CONCLUSÃO: a mensuração da espessura das tábuas ósseas vestibular e lingual em imagens de TCCB mostrou boa precisão para exames obtidos com voxel de 0,2; 0,3 ou 0,4mm. A reprodutibilidade das mensurações na região anterior da mandíbula foi mais crítica do que na região posterior.

Padronização de um método para mensuração das tábuas ósseas vestibular e lingual dos maxilares na Tomografia Computadorizada de Feixe Cônico (Cone Beam)

INTRODUÇÃO: a espessura das tábuas ósseas que recobrem os dentes por vestibular e lingual constitui um dos fatores limitantes da movimentação dentária. O avanço tecnológico em Imaginologia permitiu avaliar detalhadamente essas regiões anatômicas por meio da utilização da tomografia computadorizada de feixe cônico (TCFC). OBJETIVO: descrever e padronizar, pormenorizadamente, um método para mensuração das tábuas ósseas vestibular e lingual dos maxilares nas imagens de tomografia computadorizada de feixe cônico. METODOLOGIA: a padronização digital da posição da imagem da face deve constituir o primeiro passo antes da seleção dos cortes de TCFC. Dois cortes axiais de cada maxilar foram empregados para a mensuração da espessura do osso alveolar vestibular e lingual. Utilizou-se como referência a junção cemento-esmalte dos primeiros molares permanentes, tanto na arcada superior quanto na inferior. RESULTADOS: cortes axiais paralelos ao plano palatino foram indicados para avaliação quantitativa do osso alveolar na maxila. Na arcada inferior, os cortes axiais devem ser paralelos ao plano oclusal funcional. CONCLUSÃO: o método descrito apresenta reprodutibilidade para utilização em pesquisas, assim como para a avaliação clínica das repercussões periodontais da movimentação dentária, ao permitir a comparação de imagens pré e pós-tratamento.