874 resultados para micro structure effects


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The effects of eucalyptol were evaluated against the house fly, Musca domestica L., and blow fly, Chrysomya megacephala (F.). The bioassay of adults, using topical application, indicated that M. domestica males were more susceptible than females, with the LD50 being 118 and 177 µg/fly, respectively. A higher LD50 of C. megacephala was obtained; 197 µg/fly for males and 221 µg/fly for females. Living flies of both species yielded a shorter life span after being treated with eucalyptol. The bioassay of larvae, using the dipping method on the third instar, showed that M. domestica was more susceptible than C. megacephala, with their LC50 being 101 and 642 µg/µl, respectively. The emergence of adults, which had been treated with eucalyptol in larvae, decreased only in M. domestica. Having the volatile property, fumigation or impregnated paper test of eucalyptol or the efficacy of repellence or attractiveness merits further investigations to enhance bio-insecticidal efficacy.

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Background Over the years, food industry wastes have been the focus of a growing interest due to their content in high added-value compounds. A good example are the olive oil by-products (OOBP), which retain a great amount of phenolic compounds during olive oil production. Their structure and biological properties justify their potential use as antioxidants in other food products. The efficient recovery of phenolic compounds has been extensively studied and optimized in order to maximize their reintroduction in the food chain and contribute to a higher valorization and better management of wastes from olive oil industry. Scope and approach This paper reviews the most representative phenolic compounds described in OOBP and their biological properties. New extraction procedures to efficiently recover these compounds and the most advanced chromatographic techniques that have been used for a better understanding of the phenolic profile of these complex matrices are also referred. Finally, this paper reports the main applications of OOBP, with emphasis on their phenolic content as natural antioxidants for food applications. Key findings and conclusions Besides their antioxidant activity, phenolic compounds from OOBP have also shown antimicrobial and antitumoral properties. Their application as food antioxidants requires new extraction techniques, including the use of non-toxic solvents and, in a pilot scale, the use of filters and adsorbent resins. The inclusion of phenolic compounds from OOBP in some food matrices have improved not only their antioxidant capacity but also their sensory attributes.

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Sapindus mukorossi is an extremely valuable medicinal plant, distributed in tropical and sub-tropical regions of Asia. The aim of present review is to form a short compilation of the phytochemical composition and pharmacological properties of this multipurpose tree. The main phytoconstituents isolated and identified from different parts of this plant are triterpenoidal saponins of oleanane, dammarane and tirucullane type. The structure and chemical names of all the types of triterpenoidal saponins reported in Sapindus mukorossi are included in this review. Many research studies have been conducted to prove the plant's potential as being spermicidal, contraceptive, hepatoprotective, emetic, anti-inflammatory and anti-protozoal. The present review highlights some of the salient pharmacological uses of Sapindus mukorossi.

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Dissertation presented to obtain the Ph.D degree in Evolutionary Biology

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Dissertation presented at Faculdade de Ciências e Tecnologia from Universidade Nova de Lisboa to obtain the degree of Master in Chemical and Biochemical Engineering

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A Work Project, presented as part of the requirements for the Award of a Masters Degree in Management from the NOVA – School of Business and Economics

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Increasingly stringed regulations for diesel engine emissions have a significant impact on the required efficiency of DOC. Lowered DOC oxidation efficiency due to thermal aging effects influences the efficiency of the exhaust aftertreatment systems downstream of the DOC. In this work carried out in the Jean Le Rond d’Alembert Institute the effect of hydrothermal aging on the reactivity and structure of a commercial DOC was investigated. The characterization of the catalytic performance was carried out on a synthetic gas bench using carrots catalyst under conditions close to the realistic conditions i.e. using a synthetic gas mixture, representative of the exhaust gases from diesel engines. Different structural characterization techniques were performed: textural and morphological proprieties were analyzed by BET and TEM, the characterization of the presented crystallographic phases was performed by DRX and the determination of the number of reducible species was possible by TPR. TEM results shown, an increase of the metal particle size with the aging caused by the agglomeration of metal particles, revealing the presence of metal sintering. DRX results also suggest the presence of support sintering. Furthermore, DRX and BET results unexpectedly reveal that the most drastic aging conditions used actually activated the catalyst surface. As expected, the aging affected negatively the catalyst performance on the oxidation of methane and CO, however an improvement of the NO oxidation performance with the aging was observed. Nevertheless, for the aging conditions used, catalytic activity results show that the influence of aging in DOC performance was not significant, and therefore, more drastic aging conditions must be used.

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In this study in the field of Consumer Behavior, brand name memory of consumers with regard to verbal and visual incongruent and congruent information such as memory structure of brands was tested. Hence, four experimental groups with different constellations of verbal and visual congruity and incongruity were created to compare their brand name memory performance. The experiment was conducted in several classes with 128 students, each group with 32 participants. It was found that brands, which are presented in a congruent or moderately incongruent relation to their brand schema, result in a better brand recall than their incongruent counterparts. A difference between visual congruity and moderately incongruity could not be confirmed. In contrast to visual incongruent information, verbal incongruent information does not result in a worse brand recall performance.

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With the projection of an increasing world population, hand-in-hand with a journey towards a bigger number of developed countries, further demand on basic chemical building blocks, as ethylene and propylene, has to be properly addressed in the next decades. The methanol-to-olefins (MTO) is an interesting reaction to produce those alkenes using coal, gas or alternative sources, like biomass, through syngas as a source for the production of methanol. This technology has been widely applied since 1985 and most of the processes are making use of zeolites as catalysts, particularly ZSM-5. Although its selectivity is not especially biased over light olefins, it resists to a quick deactivation by coke deposition, making it quite attractive when it comes to industrial environments; nevertheless, this is a highly exothermic reaction, which is hard to control and to anticipate problems, such as temperature runaways or hot-spots, inside the catalytic bed. The main focus of this project is to study those temperature effects, by addressing both experimental, where the catalytic performance and the temperature profiles are studied, and modelling fronts, which consists in a five step strategy to predict the weight fractions and activity. The mind-set of catalytic testing is present in all the developed assays. It was verified that the selectivity towards light olefins increases with temperature, although this also leads to a much faster catalyst deactivation. To oppose this effect, experiments were carried using a diluted bed, having been able to increase the catalyst lifetime between 32% and 47%. Additionally, experiments with three thermocouples placed inside the catalytic bed were performed, analysing the deactivation wave and the peaks of temperature throughout the bed. Regeneration was done between consecutive runs and it was concluded that this action can be a powerful means to increase the catalyst lifetime, maintaining a constant selectivity towards light olefins, by losing acid strength in a steam stabilised zeolitic structure. On the other hand, developments on the other approach lead to the construction of a raw basic model, able to predict weight fractions, that should be tuned to be a tool for deactivation and temperature profiles prediction.

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Large chromosomal rearrangements are common in natural populations and thought to be involved in speciation events. In this project, we used experimental evolution to determine how the speed of evolution and the type of accumulated mutations depend on the ancestral chromosomal structure and genotype. We utilized two Wild Type strains and a set of genetically engineered Schizosaccharomyces pombe strains, different solely in the presence of a certain type of chromosomal variant (inversions or translocations), along with respective controls. Previous research has shown that these chromosomal variants have different fitness levels in several environments, probably due to changes in the gene expression along the genome. These strains were propagated in the laboratory at very low population sizes, in which we expect natural selection to be less efficient at purging deleterious mutations. We then measured these strains’ changes in fitness throughout this accumulation of deleterious mutations, comparing the evolutionary trajectories in the different rearrangements to understand if the chromosomal structure affected the speed of evolution. We also tested these mutations for possible epistatic effects and estimated their parameters: the number of arising deleterious mutations per generation (Ud) and each one’s mean effect (sd).

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Doctoral Program in Computer Science

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This paper presents the assessment of the out-of-plane response due to seismic loading of a masonry structure without rigid diaphragm. This structure corresponds to real scale brick masonry specimen with a main façade connected to two return walls. Two modelling approaches were defined for this evaluation. The first one consisted on macro modelling, whereas the second one on simplified micro modelling. As a first step of this study, static nonlinear analyses were conducted to the macro model aiming at evaluating the out-of-plane response and failure mechanism of the masonry structure. A sensibility analyses was performed in order to assess the mesh size and material model dependency. In addition, the macro models were subjected to dynamic nonlinear analyses with time integration in order to assess the collapse mechanism. Finally, these analyses were also applied to a simplified micro model of the masonry structure. Furthermore, these results were compared to experimental response from shaking table tests. It was observed that these numerical techniques simulate correctly the in-plane behaviour of masonry structures. However, the

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Tese de Doutoramento em Ciência e Engenharia de Polímeros e Compósitos

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Tese de Doutoramente em Ciências (área de especialização em Química).

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The study of the interaction between hair filaments and formulations or peptides is of utmost importance in fields like cosmetic research. Keratin intermediate filaments structure is not fully described, limiting the molecular dynamics (MD) studies in this field although its high potential to improve the area. We developed a computational model of a truncated protofibril, simulated its behavior in alcoholic based formulations and with one peptide. The simulations showed a strong interaction between the benzyl alcohol molecules of the formulations and the model, leading to the disorganization of the keratin chains, which regress with the removal of the alcohol molecules. This behavior can explain the increase of peptide uptake in hair shafts evidenced in fluorescence microscopy pictures. The model developed is valid to computationally reproduce the interaction between hair and alcoholic formulations and provide a robust base for new MD studies about hair properties. It is shown that the MD simulations can improve hair cosmetic research, improving the uptake of a compound of interest.