Os impactos na qualidade da água e do solo de um manancial tropical do semiárido devido ao uso e ocupação e evento de seca extrema

Human activities alter soil features, causing the deterioration of its quality. Land use and occupation in drainage basins of water supply reservoirs can change the environmental soil quality and, thus, lead to the expansion of the soil potential of being a diffuse pollution source. In the Brazilian semiarid region, the soils are generally shallow with high susceptibility to erosion, favoring the sediment and nutrients input into the superficial waterbodies, contributing to the eutrophication process. Moreover, this region has high temperatures and high evapotranspiration rates, that are generally higher than the precipitation rates, causing a negative hydric balance and big volume losses by evaporation. The water volume reduction increases the nutrients’ concentration and, therefore, exacerbates the eutrophication process, deteriorating the water quality. Thereby, we hypothesized that the eutrophication process of semiarid reservoirs is intensified both by the extreme climatic events of prolonged drought, and by the diffuse pollution due to the basin land use and occupation. The study aimed to test whether the land use and occupation activities of the basin and the severe drought events intensify the eutrophication process of a semiarid tropical reservoir. To verify the influence of human activities carried out in the water supply of drainage basin on the soil quality and the eutrophication process, we conducted the mapping of the kind of use and occupation, as well the calculation of erosion for each activity and the soil quality evaluation of the riparian zone and water quality of the water supply. For the water analyses, the samplings were carried out monthly in the deeper point, near dam. For the soil, deformed composite samples were taken for the physical and chemical attributes analysis, according to the identified land use and occupation classes. The results showed that extreme droughts drastically reduces the water volume and elevates the nutrients concentration, contributing, thus, to a bigger degradation of water quality. Furthermore, we verified that human activities in the drainage basin promote the diffuse pollution, by increasing the soil susceptibility to erosion and nutrients contents. Summarizing, our results support the investigated hypothesis that activities of land use and occupation and extreme drought generate a combined effect that provide the intensification of eutrophication process of semiarid reservoirs.

Concentração do óleo de girassol em compostos insaturados utilizando destilação molecular

Vegetable oils are characterized as important raw materials in the supplying of natural substances of interest pharmaceutical, food and cosmetic industry. Sunflower oil stands out for its important composition present in unsaturated fatty acids such as oleic acid (C18:1) and linoleic (C18:2), responsible for many health benefits. The main objective of this study is obtain enriched fractions in unsaturated compounds from refined sunflower oil. The oil used in this study was characterized by the determination of some properties, like iodine number, acid number and viscosity. A transesterification was done to transform the triglycerides into their corresponding methyl esters of fatty acids. These was submitted the molecular distillation process, for present as an efficient alternative to separation and purification of these substances, using high vacuum and low temperatures. Of the esters fractions that was obtained, were analyzed by gas chromatography. The experimental design technique was used to evaluate the influence of the temperature variation of evaporation and condensation system on the percentage obtained residue. The evaporator temperature proved to be the most influential variable on the studied response. The optimized conditions for the answer was studied at 100 °C for evaporator temperature and 10 °C for the condenser temperature. The graph of "split ratio" showed that for the lowest flow feed (1 mL/min) and higher evaporator temperature (110 °C) was obtained in the largest fraction of distillate. It also used the study of the influence of evaporator temperature on the concentration of unsaturated compounds. The best operating conditions for temperature was 90 °C reached 82.21 % of unsaturated compounds. Elimination curves of the unsaturated compounds present in the distillate stream were obtained. The simulation results of the molecular distillation process of sunflower oil showed the concentration profiles for three different feed flow rates. The speed, temperature and thickness profiles of the liquid film were obtained. The speed of the film increases as the fluid flows through the walls of the evaporator, reaching a maximum on length of 0.075 m. The film thickness decreases on the route, since many compounds are volatilized. The result of the temperature profile had to be consistent with the literature reproduced, being constant after reaching the maximum operating temperature in the length of 0.15 m. This study allowed characterizing and focusing, through experimental analysis, unsaturated compounds and observing the sunflower oil´s behavior through process simulation.

Concentração do óleo de girassol em compostos insaturados utilizando destilação molecular

Vegetable oils are characterized as important raw materials in the supplying of natural substances of interest pharmaceutical, food and cosmetic industry. Sunflower oil stands out for its important composition present in unsaturated fatty acids such as oleic acid (C18:1) and linoleic (C18:2), responsible for many health benefits. The main objective of this study is obtain enriched fractions in unsaturated compounds from refined sunflower oil. The oil used in this study was characterized by the determination of some properties, like iodine number, acid number and viscosity. A transesterification was done to transform the triglycerides into their corresponding methyl esters of fatty acids. These was submitted the molecular distillation process, for present as an efficient alternative to separation and purification of these substances, using high vacuum and low temperatures. Of the esters fractions that was obtained, were analyzed by gas chromatography. The experimental design technique was used to evaluate the influence of the temperature variation of evaporation and condensation system on the percentage obtained residue. The evaporator temperature proved to be the most influential variable on the studied response. The optimized conditions for the answer was studied at 100 °C for evaporator temperature and 10 °C for the condenser temperature. The graph of "split ratio" showed that for the lowest flow feed (1 mL/min) and higher evaporator temperature (110 °C) was obtained in the largest fraction of distillate. It also used the study of the influence of evaporator temperature on the concentration of unsaturated compounds. The best operating conditions for temperature was 90 °C reached 82.21 % of unsaturated compounds. Elimination curves of the unsaturated compounds present in the distillate stream were obtained. The simulation results of the molecular distillation process of sunflower oil showed the concentration profiles for three different feed flow rates. The speed, temperature and thickness profiles of the liquid film were obtained. The speed of the film increases as the fluid flows through the walls of the evaporator, reaching a maximum on length of 0.075 m. The film thickness decreases on the route, since many compounds are volatilized. The result of the temperature profile had to be consistent with the literature reproduced, being constant after reaching the maximum operating temperature in the length of 0.15 m. This study allowed characterizing and focusing, through experimental analysis, unsaturated compounds and observing the sunflower oil´s behavior through process simulation.

Análise tribo-termodinâmica da aplicação de nanopartículas de Al2O3 como aditivo lubrificante em compressor hermético de refrigeração

The thermodynamic performance of a refrigeration system can be improved by reducing the compression work by a particular technique for a specific heat removal rate. This study examines the effect of small concentrations of Al2O3 (50 nm) nanoparticles dispersion in the mineral oil based lubricant on the: viscosity, thermal conductivity, and lubrication characteristics as well as the overall performance (based on the Second Law of Thermodynamics) of the refrigerating system using R134a or R600a as refrigerants. The study looked at the influences of variables: i) refrigerant charge (100, 110, 120 and 130 g), ii) rotational speed of the condenser blower (800 and 1100 RPM) and iii) nanoparticle concentration (0.1 and 0.5 g/l) on the system performance based on the Taguchi method in a matrix of L8 trials with the criterion "small irreversibility is better”. They were carried pulldown and cycling tests according to NBR 12866 and NBR 12869, respectively, to evaluate the operational parameters: on-time ratio, cycles per hour, suction and discharge pressures, oil sump temperature, evaporation and condensation temperatures, energy consumption at the set-point, total energy consumption and compressor power. In order to evaluate the nanolubricant characteristics, accelerated tests were performed in a HFRR bench. In each 60 minutes test with nanolubricants at a certain concentration (0, 0.1 and 0.5 g/l), with three replications, the sphere (diameter 6.00 ± 0.05 mm, Ra 0.05 ± 0.005 um, AISI 52100 steel, E = 210 GPa, HRC 62 ± 4) sliding on a flat plate (cast iron FC200, Ra <0.5 ± 0.005 um) in a reciprocating motion with amplitude of 1 mm, frequency 20 Hz and a normal load of 1,96 N. The friction coefficient signals were recorded by sensors coupled to the HFRR system. There was a trend commented bit in the literature: a nanolubricant viscosity reduction at the low nanoparticles concentrations. It was found the dominant trend in the literature: increased thermal conductivity with increasing nanoparticles mass fraction in the base fluid. Another fact observed is the significant thermal conductivity growth of nanolubricant with increasing temperature. The condenser fan rotational speed is the most influential parameter (46.192%) in the refrigerator performance, followed by R600a charge (38.606%). The Al2O3 nanoparticles concentration in the lubricant plays a minor influence on system performance, with 12.44%. The results of power consumption indicates that the nanoparticles addition in the lubricant (0.1 g/L), together with R600a, the refrigerator consumption is reduced of 22% with respect to R134a and POE lubricant. Only the Al2O3 nanoparticles addition in the lubricant results in a consumption reduction of about 5%.

Análise tribo-termodinâmica da aplicação de nanopartículas de Al2O3 como aditivo lubrificante em compressor hermético de refrigeração

The thermodynamic performance of a refrigeration system can be improved by reducing the compression work by a particular technique for a specific heat removal rate. This study examines the effect of small concentrations of Al2O3 (50 nm) nanoparticles dispersion in the mineral oil based lubricant on the: viscosity, thermal conductivity, and lubrication characteristics as well as the overall performance (based on the Second Law of Thermodynamics) of the refrigerating system using R134a or R600a as refrigerants. The study looked at the influences of variables: i) refrigerant charge (100, 110, 120 and 130 g), ii) rotational speed of the condenser blower (800 and 1100 RPM) and iii) nanoparticle concentration (0.1 and 0.5 g/l) on the system performance based on the Taguchi method in a matrix of L8 trials with the criterion "small irreversibility is better”. They were carried pulldown and cycling tests according to NBR 12866 and NBR 12869, respectively, to evaluate the operational parameters: on-time ratio, cycles per hour, suction and discharge pressures, oil sump temperature, evaporation and condensation temperatures, energy consumption at the set-point, total energy consumption and compressor power. In order to evaluate the nanolubricant characteristics, accelerated tests were performed in a HFRR bench. In each 60 minutes test with nanolubricants at a certain concentration (0, 0.1 and 0.5 g/l), with three replications, the sphere (diameter 6.00 ± 0.05 mm, Ra 0.05 ± 0.005 um, AISI 52100 steel, E = 210 GPa, HRC 62 ± 4) sliding on a flat plate (cast iron FC200, Ra <0.5 ± 0.005 um) in a reciprocating motion with amplitude of 1 mm, frequency 20 Hz and a normal load of 1,96 N. The friction coefficient signals were recorded by sensors coupled to the HFRR system. There was a trend commented bit in the literature: a nanolubricant viscosity reduction at the low nanoparticles concentrations. It was found the dominant trend in the literature: increased thermal conductivity with increasing nanoparticles mass fraction in the base fluid. Another fact observed is the significant thermal conductivity growth of nanolubricant with increasing temperature. The condenser fan rotational speed is the most influential parameter (46.192%) in the refrigerator performance, followed by R600a charge (38.606%). The Al2O3 nanoparticles concentration in the lubricant plays a minor influence on system performance, with 12.44%. The results of power consumption indicates that the nanoparticles addition in the lubricant (0.1 g/L), together with R600a, the refrigerator consumption is reduced of 22% with respect to R134a and POE lubricant. Only the Al2O3 nanoparticles addition in the lubricant results in a consumption reduction of about 5%.

Alteração do estado trófico durante um evento de seca prolongada e seus impactos na biomassa algal de um manancial tropical da região semiárida

The main consequence of eutrophication is an increase in algal biomass, mainly cyanobacterial blooms. The high evaporation and low precipitation, characteristics of semiarid regions, contribute to the nutrients availability increase in drought periods and consequent aggravation of eutrophic condition in reservoirs. Climate changes tend to intensify eutrophication symptoms, mostly in a semiarid region. Therefore, the aim of this study was to evaluate the impact of an extended drought in algal biomass in Parelhas’s Boqueirão, a mesotrophic reservoir located in a semiarid tropical region. The low volume was associated to water quality degradation and to the high nutrients concentrations and low water transparency. The increase in nutrients availability in the water column, consequence of reduced precipitation and low reservoir’s volume, provided the necessary resources for algal growth and allowed a change in trophic state in Boqueirão reservoir. This study showed how an extended drought decreases water quality. The effect of drought in Boqueirão was late detected due to the reservoir´s low initial nutrients concentration. The reservoir´s volume reduction increased the nutrient availability along with the algal biomass increase and the reservoir´s trophic state change of mesotrophic to eutrophic.

Diversidade funcional em matas de galeria inundável e não inundável

As florestas ribeirinhas se dividem em matas ciliares e matas de galeria. As matas de galeria são importantes na manutenção dos recursos hídricos e da fauna a elas associada. Esses ambientes sofrem degradação e para a conservação e restauração são necessários estudos que entendam o funcionamento das espécies na comunidade. Os objetivos desse trabalho foram avaliar a variabilidade na área foliar específica em mata de galeria inundável do córrego do Glória (Uberlândia/MG) e mata de galeria não-inundável do ribeirão do Panga (Uberlândia/MG) e utilizar atributos reprodutivos como síndrome de polinização, síndrome de dispersão e sistema sexual, para comparação entre distintas áreas de mata de galeria inundável e também comparando com a mata de galeria não-inundável do Panga. Foram utilizados os dados florísticos já realizados nas matas de galeria não inundável do Panga (Uberlândia/MG), da mata de galeria inundável do Glória (Uberlândia/MG) e diversas outras matas de galeria inundável. A partir desses estudos foram calculados o IVC (Índice de Valor de Cobertura) e selecionadas as espécies. Para avaliar a variabilidade da área foliar específica foram utilizadas e as médias de AFE (área foliar específica) das espécies para comparação entre as duas áreas com o teste t de Student; já para analisar os padrões reprodutivos entre as matas de galeria inundável e compará-las com os padrões do Panga foram feitos testes de qui-quadrado. Os resultados do teste t mostraram que as médias das espécies da mata de galeria do Glória foram significativamente maiores do que as médias da mata de galeria do Panga. Protium heptaphyllum foi a única espécie co-ocorrente e também apresentou média significativamente maior na mata de galeria do Glória. As espécies vegetais com maiores AFE possuem uma maior captação de luz por unidade de biomassa investida, mas tendem a ter maior evaporação e perda de água. Por isso, a mata de galeria inundável, que não tem restrição hídrica para as espécies, pode apresentar maiores lâminas foliares. Com relação aos três atributos reprodutivos analisados, as áreas mostraram ser diferentes entre si e através de representação gráfica pode-se analisar que não houve padrões definidos entre as áreas, mas uma tendência a semelhanças entre várias áreas, principalmente em áreas próximas geograficamente, como as áreas de Uberlândia/MG. Quando comparados a padrões encontrados em outros estudos, as matas de galeria são semelhantes a outras áreas de floresta tropical, como alto índice de dioicia, que é relacionado a ambientes úmidos, maior porcentagem de dispersão zoocórica, especialmente por aves, e maior porcentagem de polinizadores generalistas, que são geralmente associados à dioicia.

DISPERSÕES AQUOSAS DE POLIURETANO COMO MATERIAL BASE PARA O DESENVOLVIMENTO DE SISTEMAS DE LIBERTAÇÃO CONTROLADA DE CETOPROFENO

O cetoprofeno (ácido 2-(3-benzoilfenil) propiónico) é um anti-inflamatório não esteroidal (AINE) utilizado no tratamento de uma grande variedade de doenças inflamatórias agudas e crónicas incluindo a artrite reumatoide, osteoartrite e espondilite anquilosante. A sua administração oral prolongada está associada a diversas reações gastrointestinais, tais como irritações e ulcerações. Neste contexto, é importante desenvolver sistemas alternati-vos, nomeadamente sistemas de libertação controlada para administração oral, transdér-mica ou intradérmica. Este trabalho tem como objetivo testar a possibilidade de utilização de dispersões aquosas de poliuretano (PUDs) como material de suporte para a produção de sistemas de liberta-ção controlada de cetoprofeno. Numa primeira etapa, foram sintetizadas PUDs de base poliéster (policaprolactona, PCL) e poliéter (polipropileno-glicol, PPG) utilizando o méto-do de pré-polímero modificado. As dispersões obtidas foram caracterizadas em termos de pH, viscosidade, teor de sólidos e tamanho de partícula. Numa segunda etapa, foi testada a incorporação do cetoprofeno nas PDUs produzidas utilizando duas estratégias para incre-mentar a sua solubilidade em água: (i) utilização de um co-solvente (acetona, DMSO e HYD) e (ii) utilização de um surfactante não iónico (Tween 80). A incorporação foi testada para teores de 5% e 10% (razão fármaco/polímero, m/m). Os filmes produzidos pelo méto-do da evaporação do solvente foram avaliados quanto à sua homogeneidade e caracteriza-dos por FTIR e DSC. Numa terceira fase realizaram-se estudos de libertação em tampão de fosfato salino (PBS) de pH 7.5 tendo como objetivo avaliar a viabilidade de desenvolvimen-to de diferentes tipologias de dispositivos dependendo de um compromisso entre as pro-priedades dos filmes e o comportamento de libertação. Os resultados obtidos podem ajudar na seleção do material de base mais adequado para um determinado fim. Adicionalmente, e mais importante, comprovou-se a viabilidade de utilizar PUDs como material base para o desenvolvimento de sistemas de libertação con-trolada, utilizando como exemplo o cetoprofeno. A avaliação da toxicidade e da atividade anti-inflamatória dos filmes produzidos foi considerada estando em curso neste momento no grupo do Professor Armando Cunha Júnior.

Development and characterization of Poly(L-lactic acid) (PLLA) platforms for bone tissue engineering

The development of scaffolds based on biomaterials is a promising strategy for Tissue Engineering and cellular regeneration. This work focuses on Bone Tissue Engineering, the aim is to develop electrically tailored biomaterials with different crystalline and electric features, and study their impacts onto cell biological behavior, so as to predict the materials output in the enhancement of bone tissue regeneration. It is accepted that bone exhibits piezoelectricity, a property that has been proved to be involved in bone growth/repair mechanism regulation. In addition electrical stimulations have been proved to influence bone growth and repair. Piezoelectric materials are therefore widely investigated for a potential use in bone tissue engineering. The main goal is the development of novel strategies to produce and employ piezoelectric biomaterials, with detailed knowledge of mechanisms involved in cell-material interaction. In the current work, poly (L-lactic) acid (PLLA), a synthetic semi-crystalline polymer, exhibiting biodegradibility, biocompatibility and piezoelectricity is studied and proposed as a promoter of enhanced tissue regeneration. PLLA has already been approved for implantation in human body by the Food and Drug Administration (FDA), and at the moment it is being used in several clinical strategies. The present study consists of first preparing films with different degrees of crystallinity and characterizing these PLLA films, in terms of surface and structural properties, and subsequently assessing the behavior of cells in terms of viability, proliferation, morphology and mineralization for each PLLA configuration. PLLA films were prepared using the solvent cast technique and submitted to different thermal treatments in order to obtain different degrees of crystallinity. Those platforms were then electrically poled, positively and negatively, by corona discharge in order to tailor their electrical properties. The cellular assays were conducted by using two different osteoblast cell lines grown directly onto the PLLA films:Human osteoblast Hob, a primary cell culture and Human osteosarcoma MG-63 cell line. This thesis gives also a comprehensive introduction to the area of Bone Tissue Engineering and provides a review of the work done in this field in the past until today, in that same field, including the one related with bone’s piezoelectricity. Then the experimental part deals with the effects of the crystallinity degrees and of the polarization in terms of surface properties and cellular bio assays. Three different degrees of crystallinity, and three different polarization conditions were prepared; which results in 9 different configurations under investigation.

Projeto de reabilitação energética de piscinas interiores

O presente relatório de projeto explicita as etapas da elaboração e os resultados obtidos através da realização de um projeto de reabilitação energética de um complexo de piscinas interiores. Esta reabilitação energética tem por objetivo a redução dos custos energéticos através da subtração de consumos supérfluos de energia ou da melhoria da eficiência energética dos equipamentos. Para alcançar estes objetivos recorreu-se à simulação dinâmica do edifício de modo a estimar múltiplas variáveis energéticas e identificar quais os setores e equipamentos que maior influência têm no consumo energético do complexo em estudo. Para a realização da simulação, recorreu-se a um software desenvolvido pelo DOE dos Estados Unidos da América, o Energy Plus, com o auxílio do Design Builder, que permite a criação e edição do modelo de forma mais fácil e acessível. Os valores retirados da simulação foram posteriormente comparados com valores reais. Com o complexo caraterizado e os principais consumidores identificados foi possível iniciar o estudo das medidas de melhoria da eficiência energética. As principais medidas estudadas incidiram na instalação de coberturas isotérmicas nas piscinas para reduzir a perda de energia através da evaporação e da radiação, a introdução de fontes de energia renovável como alternativa energética, substituição de elementos do sistema de iluminação e o aproveitamento de energia dissipada em equipamentos. Com este estudo, a entidade gestora do complexo encontra-se mais informada e pronta a tomar decisões que influenciem de forma significativa o consumo de energia no complexo, podendo optar pela instalação de alguma das medidas propostas.

Impact of natural and/or chemical stressors on the freeze-tolerant and euryhaline enchytraeid, Enchytraeus albidus

Rapid climatic changes are taking place in Arctic, subarctic and cold temperate regions, where predictions point to an increase in freeze-thaw events, changes in precipitation, evaporation and salinity patterns. Climate change may therefore result in large impacts in ecosystem functioning and dynamics, especially in the presence of contaminants due to intense anthropogenic activities. Even though multiple stress approaches have received increasing interest in the last decades, the number of such studies is limited. In particular, knowledge on the effect of freezethaw events and salinity fluctuations on ecotoxicology of soil invertebrates is lacking, especially important when considering supralittoral species. Therefore, the aim of this thesis was to investigate the effects of low temperature and salinity fluctuations, singly and in combination with contaminants, in the freeze-tolerant and euryhaline enchytraeid Enchytraeus albidus. The assessment of population level endpoints (survival and reproduction), along with physiological and biochemical parameters such as levels of cryoprotectants, ice/water content, oxidative stress biomarkers, cellular energy allocation, and tissue concentration of chemicals (when applied), provided new and valuable knowledge on the effects of selected physical and chemical stressors in E. albidus, and allowed the understanding of adjustments in the primary response mechanisms that enable worms to maintain homeostasis and survival in harsh environments such as polar and temperate-cold regions. The presence of moderate levels of salinity significantly increased freeze-tolerance (mainly evaluated as survival, cryoprotection and ice fraction) and reproduction of E. albidus. Moreover, it contributed to the readjustments of cryoprotectant levels, restoration of antioxidant levels and changed singnificantly the effect and uptake of chemicals (copper cadmium, carbendazim and 4-nonylphenol). Temperature fluctuations (simulated as daily freeze-thaw cycles, between -2ºC and -4ºC) caused substancial negative effect on survival of worms previsouly exposed to non-lethal concentrations of 4-nonylphenol, as compared with constant freezing (-4ºC) and control temperature (2ºC). The decrease in cryoprotectants, increase in energy consumption and the highest concentration of 4-nonylphenol in the tissues have highlighted the high energy requirements and level of toxicity experienced by worms exposed to the combined effect of contaminants and freezing-thawing events. The findings reported on this thesis demonstrate that natural (physical) and chemical stressors, singly or in combination, may alter the dynamics of E. albidus, affecting not only their survival and reproduction (and consequent presence/distribution) but also their physiological and biochemical adaptations. These alterations may lead to severe consequences for the functioning of the ecosystems along the Arctic, subarctic and cold temperate regions, where they play an important role for decomposition of dead organic matter. This thesis provides a scientific basis for improving the setting of safety factors for natural soil ecosystems, and to underline the integration of similar investigations in ecotoxicology, and eventually in risk assessment of contaminants.

Fumonisina B1 em arroz: validação de método e efeito de tratamento térmico nos níveis da micotoxina

O arroz (Oryza sativa, L.), como todos os cereais, pode ser contaminado por fungos responsáveis por danos tecnológicos, nutricionais e toxicológicos, dentre eles a produção de micotoxinas. Diversas toxinas fúngicas produzidas pelo gênero Fusarium tem sido relatadas em arroz, no entanto a fumonisina B1 (FB1) é pouco estudada neste grão. As principais características da FB1 é a alta solubilidade em solventes polares, estabilidade a altas temperaturas além de efeitos neurotóxicos e carcinogênicos. Assim o objetivo deste trabalho foi avaliar o efeito do tratamento térmico e hidrotérmico nos teores de fumonisina B1 e nas características químicas de arroz comercial. Na primeira etapa do trabalho foi adaptado um método para detecção e quantificação de FB1 em arroz cru e após cocção, por HPLC-FL. O método foi avaliado quanto aos indicativos de eficiência destacando-se o LOD (30 µg.kg-1) e a recuperação ( 90% para arroz cru e 86% pra arroz cozido). Na segunda etapa realizou-se o levantamento de ocorrência de FB1 em 05 diferentes amostras comerciais de arroz integral, branco e parboilizado da cidade de Rio Grande, RS, totalizando 9 amostras. Foi detectada a presença de FB1 em 7 das 9 amostras, sendo que os maiores índices foram encontrados em amostras de arroz parboilizado e integral apresentando níveis de contaminação entre 30 e 170 µg.kg-1. A terceira etapa do trabalho consistiu no estudo do efeito de tratamentos térmicos sobre os níveis de FB1 em amostras após aplicação de calor. Foram testados tratamento hidrotérmico com evaporação, tratamento hidrotérmico com autoclavagem e tratamento térmico seco. O maior nível de redução dos teores iniciais de FB1 foi 82,8% quando se empregou tratamento térmico seco a 125 °C/3 min. Ainda foram avaliados os efeitos do t ratamento hidrotérmico com evaporação de água na composição química e na digestibilidade protéica. Esta característica proporcionou aumento de até 100% na digestibilidade in vitro das proteínas e reduziu em média 73% do teor de contaminação com FB1.

Influência da profundidade e dos parâmetros ambientais sobre o desenvolvimento de Gracilaria birdiae (Rhodophyta, Gracilariales) em viveiro de camarão

This study evaluates the influence of depth and environmental parameters on the development of Gracilaria birdiae Plastino & Oliveira (Gracilariaceae Rhodophyta) in an organic shrimp pound (Litopenaeus vannamei) under euthrophical conditions. PVC structures (module) witch four ropes laden with 150 g of macroalgae each, were kept during 35 days at three different depths (surface, 10 and 20 cm depth). Wet biomass weighing and environmental parameters (temperature, salinity, turbidity, pH, transparence, precipitation, evaporation, insolation, accumulated solar radiation, nitrite, nitrate, ammonium and orthophosphate) were measured weekly. At all three proposed depths, the macroalgae displayed a higher biomass at the end of experiment than at the initial inoculations. The module kept at a 10 cm depth presented the greatest average biomass (186,3), followed by that kept at 20 cm (180,4 g) and the surface module (169,9 g). Biomass variations showed algae to suffer the direct effects of depths. Biomass loss was associated with the factors that influence light penetration, such as sediment deposits above the thallus, rate of evaporation and precipitation. The smallest loses occurred in the algae kept on surface (0,16%), followed by the algae kept at 20 cm (0,20%) and 10 cm (0,22%). The specific growth rate (SGR) of G. birdiae showed no significant difference between the three depths nor the sample periods. Nevertheless, the modules kept at 10 and 20 cm depths presented similar growth evolution, both growing 0,38%·per day-1, while the module kept on surface had an average SGR of 0,36%·day-1. The models related to growth rate demonstrated temperature, salinity, pH, orthophosphate, ammonium, precipitation and turbidity as the principal environmental parameters influencing the development of G. birdiae

Análisis y simulación de un rectificador trifásico controlado Active Front End (AFE)

Este artículo presenta un resultado de investigación financiado con recursos propios en el que se expone un modelo en espacio de estados de un rectificador trifásico controlado active front end. Utilizando este modelo se deriva una ley de control orientado al voltaje (VOC), enfocado en el comportamiento como carga resistiva, factor de potencia unitario, el cual es probado mediante simulación usando el Toolbox SimPowerSystem en Simulink de Matlab®.

Biodiesel a partir de óleos de alta acidez: desenvolvimento de um processo catalítico homogêneo

O presente trabalho visa o desenvolvimento de um processo para a produção de biodiesel partindo de óleos de alta acidez, aplicando um processo em duas etapas de catálise homogênea. A primeira é a reação de esterificação etílica dos ácidos graxos livres, catalisada por H2SO4, ocorrendo no meio de triglicerídeos e a segunda é a transesterificação dos triglicerídeos remanescentes, ocorrendo no meio dos ésteres alquílicos da primeira etapa e catalisada com álcali (NaOH) e álcool etílico ou metílico. A reação de esterificação foi estudada com uma mistura modelo consistindo de óleo de soja neutro acidificado artificialmente com 15%p de ácido oleico PA. Este valor foi adotado, como referência, devido a certas gorduras regionais (óleo de mamona advinda de agricultura familiar, sebos de matadouro e óleo de farelo de arroz, etc.) apresentarem teores entre 10-20%p de ácidos graxos livres. Nas duas etapas o etanol é reagente e também solvente, sendo a razão molar mistura:álcool um dos parâmetros pesquisados nas relações 1:3, 1:6 e 1:9. Outros foram a temperatura 60 e 80ºC e a concentração percentual do catalisador, 0,5, 1,0 e 1,5%p, (em relação à massa de óleo). A combinatória destes parâmetros resultou em 18 reações. Dentre as condições reacionais estudadas, oito atingiram acidez aceitável inferior a 1,5%p possibilitando a definição das condições para aplicação ótima da segunda etapa. A melhor condição nesta etapa ocorreu quando a reação foi conduzida a 60°C com 1%p de H2SO4 e razão molar 1:6. No final da primeira etapa foram realizados tratamentos pertinentes como a retirada do catalisador e estudada sua influência sobre a acidez final, utilizando-se de lavagens com e sem adição de hexano, seguidas de evaporação ou adição de agente secante. Na segunda etapa estudaram-se as razões molares de óleo:álcool de 1:6 e 1:9 com álcool metílico e etílico, com 0,5 e 1%p de NaOH assim como o tratamento da reação (lavagem ou neutralização do catalisador) a 60°C, resultando em 16 experimentos. A melhor condição nesta segunda etapa ocorreu com 0,5%p de NaOH, razão molar óleo:etanol de 1:6 e somente as reações em que se aplicaram lavagens apresentaram índices de acidez adequados (<1,0%p) coerentes com os parâmetros da ANP.