Este trabalho teve como propósito investigar a cinética de floculação de água bruta com baixa turbidez, utilizando o sulfato de alumínio (Al2(SO4)3o18H2O) e o cloreto férrico (FeCl3o6H2O) como coagulantes. Os resultados experimentais foram obtidos em ensaios de \"jar test\". A água bruta utilizada nos ensaios foi preparada em laboratório, simulando um manancial superficial eutrofizado contendo células da cianobactéria Microcystis aeruginosa. Foram testadas 5 dosagens distintas de cada coagulante, 3 valores de G, 2 valores de TAS e 12 tempos de floculação. Utilizou-se a turbidez como medida principal de avaliação dos resultados experimentais. O valor de turbidez inicial (N0) foi corrigido, levando-se em consideração o acréscimo de turbidez em função das dosagens de coagulante. Determinou-se que as dosagens mais efetivas, em termos de remoção de turbidez, foram 20 mg.L-1 para o sulfato de alumínio e 40 mg.L-1 para o cloreto férrico (ambas expressas como massa de coagulante). Para ambos os coagulantes, constatou-se que G = 20 s-1 e TAS = 27 m3.m-2.dia-1 resultaram nas melhores eficiências de remoção de turbidez. Verificou-se também a variação do potencial zeta em função das dosagens de coagulante. Observou-se que o aumento da dosagem de coagulante leva à redução do potencial zeta, aproximando-o do ponto isoelétrico. Porém, o ponto isoelétrico não necessariamente coincide com a melhor eficiência em termos de remoção de turbidez. Com base nos resultados experimentais, foi proposta uma modificação ao modelo clássico da cinética de floculação de suspensões coloidais. Nesta, foi incluso um segundo termo referente à ruptura de flocos (quebra irreversível). O ajuste do modelo proposto foi obtido através de procedimentos de iteração numérica computacional com a função \"Solver\" do programa Microsoft Excel®. Foram calculados os valores das constantes KA, KB e KC do modelo proposto. Amostras do lodo gerado nos ensaios de cinética de floculação foram caracterizadas visualmente através de microscopia eletrônica de varredura (MEV). / The purpose of this work was to investigate flocculation kinetics of low-turbidity raw water, using aluminum sulfate (Al2(SO4)3o18H2O) and ferric chloride (FeCl3o6H2O) as coagulants. Experimental results were obtained in jar tests. Raw water used in the jar tests was prepared in laboratory, simulating a eutrophic natural water source containing cells of the cyanobacteria Microcystis aeruginosa. 5 different coagulant doses were tested for each coagulant, 3 G values, 2 SLR values and 12 flocculation times. Turbidity was selected as the major parameter for experimental results analysis. Initial turbidity values (N0) were corrected taking into account turbidity increase due to coagulant dosing. In terms of turbidity removal, it was determined that the most effective dosage for aluminum sulfate was 20 mg.L-1, and for ferric chloride, 40 mg.L-1 (both expressed as coagulant mass). For both coagulants, it was found that G = 20 s-1 and SLR = 27 m3.m-2.day-1 resulted in the best turbidity removal efficiencies. Zeta potential variation, due to coagulant dosing, was also verified. It was noted that increasing coagulant dosing led to zeta potential reduction, bringing it closer to the isoelectric point. However, the isoelectric point does not necessary coincides with the best turbidity removal efficiency. Based on the experimental results, it was proposed a modification to the classic colloidal suspension flocculation kinetics model. In this modification, a second term regarding floc rupture (irreversible breakage) was included. Through computer numeric iteration using Microsoft Excel®\'s \"Solver\" function, the proposed model adjustment was obtained. Kinetics constants KA, KB e KC values, from the proposed model, were calculated. Sludge samples, generated during flocculation kinetics tests, were visually characterized through scanning electronic microscopy (SEM).

La protéine FUR (Ferric Uptake Regulator) est un régulateur global ubiquitaire chez les bactéries Gram-négatives. Sa liaison au Fe2+, in vivo, entraîne la répression de l'expression des gènes qu'elle contrôle. Ce travail est une étude structurale par RMN de la forme dimérique non activée de FUR d'Escherichia coli, un dimère de 2*17 kDa contenant un ion zinc par monomère. Une forme monomérique oxydée, capable de dimériser en présence de réducteur et de zinc, a également été isolée et étudiée. Le dichroïsme circulaire et la RMN montrent que la dimérisation entraîne une structuration du domaine C-terminal lors de l'incorporation du zinc. Les structures secondaires du domaine N-terminal du monomère et du dimère sont très proches. Seuls les premiers résidus sont structurés en hélice Α dans le monomère et déstructurés dans le dimère non activé. Cette hélice, observée dans le dimère activé de FUR de P. aeruginosa, pourrait jouer un rôle dans le mécanisme de régulation. Une protéine tronquée (FUR1-82) a été construite, purifiée, cristallisée. Sa structure est superposable à celle du domaine N-terminal de FUR de P. aeruginosa et le spectre 1H-15N-HSQC est superposable aux signaux du domaine N-terminal de FUR monomère. L'étude, par anisotropie de fluorescence, de la liaison du monomère et du dimère à l'ADN montre qu'ils se lient spécifiquement à l'ADN en présence de métal, contrairement à la forme tronquée. L'affinité du monomère pour l'ADN est 5 fois plus faible que celle du dimère en excès de métal. L'ensemble de ces données nous a permis de proposer un mécanisme de dimérisation de FUR d'E. coli ainsi qu'un mécanisme d'activation mettant en jeu cette hélice Α N-terminale.

The combination of moving bed biofilm reactors and membrane bioreactors (MBBR-MR) can compensate for the drawbacks of both of these systems and further increase their acceptance and application in wastewater treatment industries. Despite the potential benefits of a MBBR-MR technology there has only been limited study of this configuration. The present study consisted of an overall assessment of the performance of a combined MBBR-MR system under high and low loading rates. Since colloidal matter in mixed liquor suspended solid (MLSS) is considered as one of the important contributors to membrane fouling, pre-treatment of membrane feed by coagulation was investigated for improving membrane performance. The performance of the MBBR-MR was assessed based on its chemical oxygen demand (COD) removal efficiency and membrane fouling mechanisms. The study was carried out using pilot-scale MBBR and bench-scale batch membrane filtration setups (Millipore Inc. Bedford, MA). The pilot MBBR had a working volume of 1.8 m3 and a 30% carrier fill fraction. The MBBR was operated with loading rates of 160 ± 44 g/m2/d (hydraulic residence time (HRT) of 4.6 h) and 223 g/m2/d (HRT of 2.6 h). The MBBR feed was obtained from a starch recovery line in a potato chip processing factory. The carriers were mixed by coarse bubble aeration and the dissolved oxygen (DO) was maintained above 2 mg/l. Preliminary jar test trials (based on turbidity removal) were performed in order to obtain an optimal dosage of coagulants for subsequent ultrafiltration (UF) tests. The efficiency of three coagulants (alum, ferric chloride and a blend of polyaluminum chloride and polyamine) was evaluated. The membranes were composed of polyethersulfone (PES) and had a pore size of 0.05 microns. The results of this study indicate that the combination of MBBR with membrane filtration can be operated at relatively high loading rates to yield a constant high quality permeate that is suitable for water reuse purposes. Fouling of the membrane by the wastewater was found to be substantially reduced by treatment with the MBBR. The reversible and irreversible fouling of the MBBR effluent were 56 and 63%, respectively, of that observed with the raw wastewater. The MBBR Loading-rate was found to affect treatment efficiency of the MBBR-MR and membrane performance. Operation under the elevated loading-rate conditions HRT = 2.6 hours) resulted in an increase in the irreversible fouling of the membranes (60% on average). The addition of all the coagulants in this study was found to decrease the fouling of the membrane. However, the extent of the pre-coagulation effect on membrane fouling was found to strongly depend on the type and dosage of the coagulant and the MBBR effluent characteristics. All the coagulants were effective in decreasing membrane fouling at their optimal dosages which was determined in preliminary jar tests. Ferric chloride performed the best as a pretreatment coagulant compared to alum (Aluminum sulfate) and the coagulant blend with reductions in both reversible and irreversible fouling (43-86% and 51-71%, respectively) and increased consistency (in decreasing fouling) as compared to the other coagulants. Alum had no effect on irreversible fouling and the coagulant blend significantly increased irreversible fouling in some trials (up to 196% or by a factor of 3 when overdosed). Additionally, alum and the blend were, on average, 29% and 7%, less effective than ferric chloride in reducing reversible fouling under the conditions and dosages tested.

Development of nanostructures as MR contrast agent will significantly improve the field of disease diagnostics. Contrast agents such as iron oxide nanoparticles are less toxic compared to more commonly used gadolinium based agents. A subclass of iron based nano particles are super paramagnetic iron oxide nano particles, (SPIOs) which are widely studied MR contrast agents useful in both imaging and drug delivery applications. In this work, SPIOs were synthesized and characterized and used for cellular tracking and multi modal labeling. A new solvent exchange method was utilized to coat different core size iron oxide nano particles. SPIOs were characterized for in-vivo imaging using MR and they had a very uniform size distribution which was determine using dynamic light scattering (DLS) and transmission electron microscopy. Furthermore, blood circulation half-life of 16nm SPIOs were determined through tail vein injection. SPIOs have many applications among which is the in vivo tracking of stem cells which is critical for determination of stem cells fate after injection. Magnetic Resonance (MR) as a non-invasive method can provide significant information about the fate of the cells as well as determination of the success rate of therapeutic cellular deliveries. Mesenchymal stem cells can be loaded with super paramagnetic iron oxide nano particles (SPIOs) and have their movements followed once planted in vivo. We present our findings on the effect of SPIO concentration and stem cell density on the MR signal and transverse relaxation time. Our preliminary results indicated that SPIOs do not cause mesenchymal stem cell cytotoxicity and do not affect proliferation ability up to 200 μg/ml concentration. The release of the nanoparticles was investigated 24 hours post internalization and the result showed that SPIOs will stay inside the cell. We also found that the contrast increases in a concentration dependent manner. Our results suggest that using MR with low concentration of SPIOs is a novel and promising method for tracking of mesenchymal stem cells. In this work SPIOs were also labeled with 64Cu to investigate their potential for multi modal positron emission tomography (PET) MR imaging. Dual modality PET MR SPIO contrast agent can be synthesized to image diseases such as cancer and atherosclerosis. The advantage is the non-invasive and early detection of disease at molecular lever before it has spread to late stages or in case of the atherosclerosis before the plaque has blocked the vessel. To develop a multi modal contrast agent, a positron emitter, 64Cu (half-life of 12.701 ± 0.002 hours), was used in labeling and synthesis was performed all in one step with the addition of 64Cu chelator, 14-PE DTPA followed by radiolabeling for both 6.5nm SPIO and 17nm SPIO. After labeling and purification with the desalting column, the amount of dissociated 64Cu in the solution was determined using radio thin layer chromotagraphy (TLC) and the particle was shown to have minimum amount of fee 64Cu. Serum stability of labeled SPIO was determined in vitro by incubating 64Cu-labeled SPIOs in mouse serum at 37 °C for 24 hr with constant shaking. Radio TLC result then revealed that 64Cu stays bounded to the SPIO after 24 hours in mouse serum. This means that 64Cu labeled SPIO has a great potential as a dual modality contrast agents and further in-vivo studies are required to verify the findings.

Diffuse Layer Modeling was used to describe single and multi-solute adsorption of Pb(II), Cu(II), Zn(II) and Cd(II) to ferrihydrite and As(V), V(V) Si and Ca(II) on granular ferric hydroxide, a commercially available iron oxide. Macroscopic data were used in conjunction with x-ray adsorption spectroscopy (XAS) data to evaluate the diffuse layer surface complexation model (DLM) for predicting sorption over a range of conditions. A self-consistent database was created for each of the adsorbents. The DLM provided excellent fits to the single solute data for the ferrihydrite system with the incorporation of spectroscopic evidence. Little competition was seen in the bisolute systems, except under very high coverages. While the DLM captured the lack of competition under low and medium coverages, competitive effects were not adequately modeled by the updated DLM for high coverages. Challenges remain in adequately describing metal removal when sorption may not be the primary mechanism of removal. The capabilities of the DLM were then evaluated for describing and predicting multisolute sorption to granular ferric hydroxide (GFH). The model can adequately describe anion competition, but the electrostatic effects due to outer sphere sorption were overpredicted, leading to an inadequate model fit for As(V) and Ca²⁺ systems. Despite the limitations of the DLM, it may be an appropriate compromise between goodness of fit and number of parameters for future integration into dynamic transport models and thermodynamic databases. / text

The combination of moving bed biofilm reactors and membrane bioreactors (MBBR-MR) can compensate for the drawbacks of both of these systems and further increase their acceptance and application in wastewater treatment industries. Despite the potential benefits of a MBBR-MR technology there has only been limited study of this configuration. The present study consisted of an overall assessment of the performance of a combined MBBR-MR system under high and low loading rates. Since colloidal matter in mixed liquor suspended solid (MLSS) is considered as one of the important contributors to membrane fouling, pre-treatment of membrane feed by coagulation was investigated for improving membrane performance. The performance of the MBBR-MR was assessed based on its chemical oxygen demand (COD) removal efficiency and membrane fouling mechanisms. The study was carried out using pilot-scale MBBR and bench-scale batch membrane filtration setups (Millipore Inc. Bedford, MA). The pilot MBBR had a working volume of 1.8 m3 and a 30% carrier fill fraction. The MBBR was operated with loading rates of 160 ± 44 g/m2/d (hydraulic residence time (HRT) of 4.6 h) and 223 g/m2/d (HRT of 2.6 h). The MBBR feed was obtained from a starch recovery line in a potato chip processing factory. The carriers were mixed by coarse bubble aeration and the dissolved oxygen (DO) was maintained above 2 mg/l. Preliminary jar test trials (based on turbidity removal) were performed in order to obtain an optimal dosage of coagulants for subsequent ultrafiltration (UF) tests. The efficiency of three coagulants (alum, ferric chloride and a blend of polyaluminum chloride and polyamine) was evaluated. The membranes were composed of polyethersulfone (PES) and had a pore size of 0.05 microns. The results of this study indicate that the combination of MBBR with membrane filtration can be operated at relatively high loading rates to yield a constant high quality permeate that is suitable for water reuse purposes. Fouling of the membrane by the wastewater was found to be substantially reduced by treatment with the MBBR. The reversible and irreversible fouling of the MBBR effluent were 56 and 63%, respectively, of that observed with the raw wastewater. The MBBR Loading-rate was found to affect treatment efficiency of the MBBR-MR and membrane performance. Operation under the elevated loading-rate conditions HRT = 2.6 hours) resulted in an increase in the irreversible fouling of the membranes (60% on average). The addition of all the coagulants in this study was found to decrease the fouling of the membrane. However, the extent of the pre-coagulation effect on membrane fouling was found to strongly depend on the type and dosage of the coagulant and the MBBR effluent characteristics. All the coagulants were effective in decreasing membrane fouling at their optimal dosages which was determined in preliminary jar tests. Ferric chloride performed the best as a pretreatment coagulant compared to alum (Aluminum sulfate) and the coagulant blend with reductions in both reversible and irreversible fouling (43-86% and 51-71%, respectively) and increased consistency (in decreasing fouling) as compared to the other coagulants. Alum had no effect on irreversible fouling and the coagulant blend significantly increased irreversible fouling in some trials (up to 196% or by a factor of 3 when overdosed). Additionally, alum and the blend were, on average, 29% and 7%, less effective than ferric chloride in reducing reversible fouling under the conditions and dosages tested.

Foi realizado um experimento com a finalidade de apresentar um protocolo preciso, simples, rápido e de baixo custo para determinar os coeficientes de metabolizabilidade dos nutrientes e o valor energético das dietas. Para tal, determinaram-se os CMMS, CMPB e CMEB e EMAn através da comparação de diferentes metodologias de digestibilidade in vivo que incluem a utilização ou não de indicador Cr2O3 a 0,5% (coleta parcial) ou marcador Fe2O3 a 1% e a aplicação ou não de jejum (0, 4, 6 e 8 horas) pré-inicio de coleta e pós-período de alimentação. Também a duração do período de coleta foi testada (3 ou 5 dias). Foi estudado o efeito dos períodos de jejum sobre o tamanho dos órgãos digestivos. Foram utilizados 81 frangos de corte, machos, com 21 dias de idade, distribuídos individualmente em gaiolas de metabolismo, constituindo 9 tratamentos (TRAT) com 9 repetições em delineamento completamente casualizado. Em todos os TRAT houve 4 dias de adaptação à uma dieta única, com 3055 kcal EM/kg, à base de milho e farelo de soja. A água foi fornecida à vontade. Após o período de coleta, 5 aves por TRAT, que receberam jejum, foram pesadas e abatidas e o papo, moela+proventrículo, intestino delgado e cólon+ceco foram pesados, bem como o conteúdo presente em cada um. Através do aparecimento do marcador foi determinada a duração da passagem de digesta pelo TGI das aves. O tempo de passagem foi considerado como o tempo entre o fornecimento da dieta com óxido férrico e o início do aparecimento das excretas marcadas. Os coeficientes de metabolismo e a energia não diferiram significativamente na coleta total comparandose 3 ou 5 dias de coleta (P>0,05). O uso do marcador Fe2O3 e três dias de coleta, resultou em menor valor do CMPB (P<0,02) em relação à coleta total sem marcador. Na metodologia de coleta parcial com 5 dias de coleta, observou-se coeficientes de menor valor para todas as respostas (P<0,05), comparados a 3 dias de coleta. O uso da metodologia de coleta total resultou em maiores CMMS e CMPB (P<0,05) comparado à coleta parcial, em função de uma taxa incompleta de recuperação do Cr2O3 na excreta. Não foi observada influencia do jejum sobre o tamanho dos órgãos, indicando que em até 8 horas de jejum não há mudança no tamanho absoluto ou relativo dos mesmos. No entanto, o peso relativo do jejuno das aves submetidas a 4, 6 e 8 horas de jejum foi maior (P<0,03) do que o das aves sem jejum. O tempo médio de passagem da ração foi estimado em 228 minutos. Conclui-se que a coleta total de excretas, por um período de 3 dias, sem o uso de jejum, resulta no melhor método de avaliação de ingredientes e ração. / One experiment was conducted in order to define a reliable, easy to apply and non expensive protocol to determinate nutrient and energy metabolizability values of broiler chicken diets. For this purpose, metabolizability coefficients (MC) of dry matter (DM); crude protein (CP); gross energy (GE) and nitrogen-corrected apparent metabolizable energy (AMEn) were calculated through the comparison of different in vivo digestibility methodologies including the utilization of Cr2O3 (0,5%) as an indicator (partial collection) or Fe2O3 (1%) as a marker; fasting, prior to excreta collection and at the end of the feeding period (0, 4, 6 and 8 hours). Also, two excreta collection periods were tested (3 and 5 days). It was assessed the effect of fasting on digestive organs weight. Eighty one 21 days male broilers were distributed individually in metabolic cages used distributed in nine treatments (T) and nine replicates per T, in a completely randomized design. Birds were held in individual metabolism cages located in a controlledtemperature room. All T had a 4 day adaptation period to a single diet of 3055 kcal ME/kg, based on corn and soybean meal. Water was offered ad libitum. At the end of fasting, 5 birds per T that received fasting were sacrificed by cervical dislocation and weighed. Crop, proventriculus+gizzard, small intestine and the ceca+colon were removed and weighed individually as their contents as well. The passage time along broiler GIT was measured with ferric oxide as a marker. The passage time was taken as the time elapsed from time of marker administration to time of the first observation of droppings red color. Metabolism coefficients and energy were not significantly different between 3 and 5 days of total collection (P>0,05). CPMC was lower (P<0,02) for Fe2O3 utilization and 3 days excreta collection compared to the total collection. With the methodology of partial collection with 5 days of collection, it was observed the lowest values for all the responses (P<0,05), compared to 3 days collection period. The use of the total collection methodology produced the highest DMMC and CPMC (P<0,05) compared to partial collection, due to the incomplete recovery of the Cr2O3 from the excreta. No fasting influence was observed on the digestive organ sizes, indicating that until 8 hours of fasting no changes are observed in either relative or absolute organs weight. However, the relative jejunum weight of birds submitted to 4, 6 and 8 hours was higher (P<0,03) than those of birds under no fasting. The mean passage time of fed through broiler GIT was 228 minutes. It was conclude that total collection, during a 3 days period, without fasting utilization, is the best methodology for poultry ingredient and fed evaluation.

Les travaux présentés dans ce mémoire sont consacrés à l'étude des processus d'adsorption des anions phosphate par la rouille verte ferrique carbonatée et la ferrihydrite. L'objectif final vise une application au traitement des eaux usées en milieu rural. La synthèse des deux oxydes de fer a été réalisée et leurs propriétés physico-chimiques caractérisées. Un intérêt particulier a été consacré à comparer les propriétés structurales de la rouille verte ferrique en fonction de différents paramètres de synthèse. Une étude approfondie des propriétés physico-chimiques de surface de la ferrihydrite par spectroscopie de photoélectrons X a quant à elle été réalisée. La réactivité de ces deux oxydes a ensuite été abordée en mode discontinu où l'équation cinétique du pseudo-second ordre et le modèle d'isotherme de Freundlich offrent les meilleurs ajustements. L'influence de divers paramètres a été prise en compte comme le pH, la force ionique, etc. Le mode continu a été envisagé sur un matériau de filtration constitué de l'oxyde de fer déposé sur de la pouzzolane. La méthode de fabrication ainsi que les conditions optimales de préparation du matériau de filtration ont été déterminées. Les mécanismes d'adsorption en condition de flux hydrodynamique ont alors mis en évidence des phénomènes advectifs, diffusifs et une régionalisation de l'eau régissant l'adsorption au sein de la colonne. Des informations telles que les capacités d'adsorption ou l'influence du débit sur le processus d'adsorption ont pu être également obtenues. Une expérience préliminaire sur une eau usée prétraitée met finalement en évidence une quantité adsorbée particulièrement intéressante pour une application industrielle potentielle / The Ph.D. work, presented in this manuscript, is devoted to evaluating phosphate adsorption process on carbonate ferric green rust and ferrihydrite. The main objective concerns an application for the treatment of waste water in rural areas. Both iron oxides are first synthesized and their physico-chemical properties characterized. The ferric green rust structural properties differences as a function of synthesis parameters such as aging period and addition of hydrogen peroxide solution is of particular interest. A detailed study of surface physico-chemical properties by X Photoelectron Spectroscopy is carried out in the case of ferrihydrite. The reactivity of these two iron oxides is then evaluated in batch experiments. Adsorption process follows the pseudo-second order kinetic equation and Freundlich isotherm model which give the best adjustments of experimental data. The influence of various parameters such as pH, ionic strength, etc on phosphate adsorption is also taken into account. Column experiments are afterwards carried out by using filtration material constituted of iron oxide deposited onto pozzolana. The optimal conditions to prepare this filtration material are naturally predetermined. Phosphate adsorption in hydrodynamic mode is characterized by advective and diffusive mechanisms and water regionalization which govern the adsorption process in the column. Moreover, phosphate adsorption capacity and flow rate influence on adsorption process are obtained. Finally, a preliminary experiment on a pre-treated waste water finally shows that the filtration material is potentially interesting for an industrial application

soldagem de aços inoxidáveis duplex AID SAF 2205 utilizando o processo Metal Active Gas (MAG) ainda tem poucos dados e referências, estes aços são conceituados devido ao seu equilíbrio entre resistência mecânica e à corrosão, resultado de sua microestrutura composta por austenita e ferrita. A soldagem dos aços inoxidáveis duplex exige um controle de aporte térmico, da composição química do metal de adição e gás de proteção. Mínimas mudanças em parâmetros e composição dos consumíveis podem afetar diretamente a estrutura formada na região da solda. Neste trabalho, o objetivo foi estudar a influência da utilização do processo de soldagem MAG com diferentes energias aplicadas ao AID SAF 2205, sobre a resistência à corrosão das amostras resultantes. Foram usados quatro valores de energias de soldagem, entre 0,6 e 1,1 kJ/mm, sendo a maior energia limitada à espessura das chapas, que era de 5 mm. Quando foi analisada a microestrutura formada na região da solda, a quantificação de ferrita na zona afetada pelo calor apresentou uniformidade nas amostras, independendo da energia de soldagem. Contudo, a quantidade de ferrita no metal de solda diminuiu à medida que a energia aumentou. A precipitação de nitretos de cromo foi observada no interior de alguns grãos de ferrita e/ou próximo a regiões com austenita secundária intragranular. Os perfis de microdureza Vickers não apresentaram nenhum valor acima de 300 HV, e nenhum comportamento diferenciado de acordo com área de indentação. A resistência à corrosão não apresentou mudanças consideráveis, o metal base e as regiões da solda nas quatro condições se comportaram de forma muito similar. Os ensaios de imersão em cloreto férrico, seguindo a ASTM G48, permitiram observar a formação de pites, mas a quantidade e densidade destes não pode ser associada a uma região da solda específica ou variação de energia de soldagem. Os valores de parâmetros eletroquímicos, OCP, ECORR, e EPIT, após os ensaios de polarização potenciodinâmica de acordo com a ASTM G5, tiveram pouca variação, mostrando um comportamento em corrosão similar para o metal base e para os metais de solda das quatro diferentes condições de energia de soldagem empregadas. / Welding of AID SAF 2205 duplex stainless steels using the Metal Active Gas (MAG) process still has few data and references, these steels are conceptualized due to their balance between mechanical resistance and corrosion, resulting from their microstructure composed of austenite and ferrite. The welding of duplex stainless steels requires a control of the thermal input, the chemical composition of the addition metal and the shielding gas. Minimal changes in parameters and composition of consumables will directly affect the structure formed in the region of the weld. In this work, the objective was to study the influence of the MAG welding process with different energies applied to AID SAF 2205, on the corrosion resistance of the resulting samples. Four values of welding energies were used, between 0.6 and 1.1 kJ / mm, with the greatest energy limited to the thickness of the plates, which was 5 mm. When the microstructure formed in the region of the weld was analyzed, the quantification of ferrite in the zone affected by the heat showed uniformity in the samples, independent of the welding energy. However, the amount of ferrite in the weld metal decreased as the energy increased. The precipitation of chromium nitrides was observed in the intermetallic was associated with grain boundaries α / γ, inside some ferrite grains, close to regions with secondary intragranular austenite. The Vickers microhardness profiles showed no value above 300 HV, and no behavior differed according to the indentation area. The corrosion resistance did not change considerably, the base metal and the regions of the weld in the four conditions behaved very similarly. Ferric chloride immersion assays, following ASTM G48, allowed to observe the formation of pites, but the amount and density thereof can not be associated with a specific weld region or weld energy variation. The values of electrochemical parameters, OCP, ECORR, and EPIT, after the potentiodynamic polarization tests according to ASTM G5, showed little variation, showing a similar corrosion behavior for the base metal and the solder metals of the four Different welding energy conditions employed.

Foi realizado um experimento com a finalidade de apresentar um protocolo preciso, simples, rápido e de baixo custo para determinar os coeficientes de metabolizabilidade dos nutrientes e o valor energético das dietas. Para tal, determinaram-se os CMMS, CMPB e CMEB e EMAn através da comparação de diferentes metodologias de digestibilidade in vivo que incluem a utilização ou não de indicador Cr2O3 a 0,5% (coleta parcial) ou marcador Fe2O3 a 1% e a aplicação ou não de jejum (0, 4, 6 e 8 horas) pré-inicio de coleta e pós-período de alimentação. Também a duração do período de coleta foi testada (3 ou 5 dias). Foi estudado o efeito dos períodos de jejum sobre o tamanho dos órgãos digestivos. Foram utilizados 81 frangos de corte, machos, com 21 dias de idade, distribuídos individualmente em gaiolas de metabolismo, constituindo 9 tratamentos (TRAT) com 9 repetições em delineamento completamente casualizado. Em todos os TRAT houve 4 dias de adaptação à uma dieta única, com 3055 kcal EM/kg, à base de milho e farelo de soja. A água foi fornecida à vontade. Após o período de coleta, 5 aves por TRAT, que receberam jejum, foram pesadas e abatidas e o papo, moela+proventrículo, intestino delgado e cólon+ceco foram pesados, bem como o conteúdo presente em cada um. Através do aparecimento do marcador foi determinada a duração da passagem de digesta pelo TGI das aves. O tempo de passagem foi considerado como o tempo entre o fornecimento da dieta com óxido férrico e o início do aparecimento das excretas marcadas. Os coeficientes de metabolismo e a energia não diferiram significativamente na coleta total comparandose 3 ou 5 dias de coleta (P>0,05). O uso do marcador Fe2O3 e três dias de coleta, resultou em menor valor do CMPB (P<0,02) em relação à coleta total sem marcador. Na metodologia de coleta parcial com 5 dias de coleta, observou-se coeficientes de menor valor para todas as respostas (P<0,05), comparados a 3 dias de coleta. O uso da metodologia de coleta total resultou em maiores CMMS e CMPB (P<0,05) comparado à coleta parcial, em função de uma taxa incompleta de recuperação do Cr2O3 na excreta. Não foi observada influencia do jejum sobre o tamanho dos órgãos, indicando que em até 8 horas de jejum não há mudança no tamanho absoluto ou relativo dos mesmos. No entanto, o peso relativo do jejuno das aves submetidas a 4, 6 e 8 horas de jejum foi maior (P<0,03) do que o das aves sem jejum. O tempo médio de passagem da ração foi estimado em 228 minutos. Conclui-se que a coleta total de excretas, por um período de 3 dias, sem o uso de jejum, resulta no melhor método de avaliação de ingredientes e ração. / One experiment was conducted in order to define a reliable, easy to apply and non expensive protocol to determinate nutrient and energy metabolizability values of broiler chicken diets. For this purpose, metabolizability coefficients (MC) of dry matter (DM); crude protein (CP); gross energy (GE) and nitrogen-corrected apparent metabolizable energy (AMEn) were calculated through the comparison of different in vivo digestibility methodologies including the utilization of Cr2O3 (0,5%) as an indicator (partial collection) or Fe2O3 (1%) as a marker; fasting, prior to excreta collection and at the end of the feeding period (0, 4, 6 and 8 hours). Also, two excreta collection periods were tested (3 and 5 days). It was assessed the effect of fasting on digestive organs weight. Eighty one 21 days male broilers were distributed individually in metabolic cages used distributed in nine treatments (T) and nine replicates per T, in a completely randomized design. Birds were held in individual metabolism cages located in a controlledtemperature room. All T had a 4 day adaptation period to a single diet of 3055 kcal ME/kg, based on corn and soybean meal. Water was offered ad libitum. At the end of fasting, 5 birds per T that received fasting were sacrificed by cervical dislocation and weighed. Crop, proventriculus+gizzard, small intestine and the ceca+colon were removed and weighed individually as their contents as well. The passage time along broiler GIT was measured with ferric oxide as a marker. The passage time was taken as the time elapsed from time of marker administration to time of the first observation of droppings red color. Metabolism coefficients and energy were not significantly different between 3 and 5 days of total collection (P>0,05). CPMC was lower (P<0,02) for Fe2O3 utilization and 3 days excreta collection compared to the total collection. With the methodology of partial collection with 5 days of collection, it was observed the lowest values for all the responses (P<0,05), compared to 3 days collection period. The use of the total collection methodology produced the highest DMMC and CPMC (P<0,05) compared to partial collection, due to the incomplete recovery of the Cr2O3 from the excreta. No fasting influence was observed on the digestive organ sizes, indicating that until 8 hours of fasting no changes are observed in either relative or absolute organs weight. However, the relative jejunum weight of birds submitted to 4, 6 and 8 hours was higher (P<0,03) than those of birds under no fasting. The mean passage time of fed through broiler GIT was 228 minutes. It was conclude that total collection, during a 3 days period, without fasting utilization, is the best methodology for poultry ingredient and fed evaluation.