Homogenization of nonlinear composites for multiscale analysis

A composite is a material made out of two or more constituents (phases) combined together in order to achieve desirable mechanical or thermal properties. Such innovative materials have been widely used in a large variety of engineering fields in the past decades. The design of a composite structure requires the resolution of a multiscale problem that involves a macroscale (i.e. the structural scale) and a microscale. The latter plays a crucial role in the determination of the material behavior at the macroscale, especially when dealing with constituents characterized by nonlinearities. For this reason, numerical tools are required in order to design composite structures by taking into account of their microstructure. These tools need to provide an accurate yet efficient solution in terms of time and memory requirements, due to the large number of internal variables of the problem. This issue is addressed by different methods that overcome this problem by reducing the number of internal variables. Within this framework, this thesis focuses on the development of a new homogenization technique named Mixed TFA (MxTFA) in order to solve the homogenization problem for nonlinear composites. This technique is based on a mixed-stress variational approach involving self-equilibrated stresses and plastic multiplier as independent variables on the Reference Volume Element (RVE). The MxTFA is developed for the case of elastoplasticity and viscoplasticity, and it is implemented into a multiscale analysis for nonlinear composites. Numerical results show the efficiency of the presented techniques, both at microscale and at macroscale level.

Multiscale comparative analysis of marine biominerals and their ecological implications

Marine biomineralizing organisms provide a fundamental link between biology and environment. Calcified structure are important archives that can provide us main means of understanding organism adaptation, habits, environmental characteristics, and to look back in time and explore the past climate and their evolutionary history. In fact, biomineralized structures retain an unparalleled record of current and past ocean conditions through the investigation of their microchemistry and isotopes. This thesis considers aspects of two different biomineralization systems: fish otolith and coral skeletons at macro-, micro- and nanoscale, with the aim to understand how their morphology, structural characteristics and compositions can provide information of their functionality, and the environmental, behavioural, and evolutionary context in which organisms are framed. To this end, I applied a multidisciplinary approach in the scope to investigate calcified structures as “information recorders” and as models to study the phenotypic plasticity.

Orchestration of multiscale model for computational oncology

Cancer is a challenging disease that involves multiple types of biological interactions in different time and space scales. Often computational modelling has been facing problems that, in the current technology level, is impracticable to represent in a single space-time continuum. To handle this sort of problems, complex orchestrations of multiscale models is frequently done. PRIMAGE is a large EU project that aims to support personalized childhood cancer diagnosis and prognosis. The goal is to do so predicting the growth of the solid tumour using multiscale in-silico technologies. The project proposes an open cloud-based platform to support decision making in the clinical management of paediatric cancers. The orchestration of predictive models is in general complex and would require a software framework that support and facilitate such task. The present work, proposes the development of an updated framework, referred herein as the VPH-HFv3, as a part of the PRIMAGE project. This framework, a complete re-writing with respect to the previous versions, aims to orchestrate several models, which are in concurrent development, using an architecture as simple as possible, easy to maintain and with high reusability. This sort of problem generally requires unfeasible execution times. To overcome this problem was developed a strategy of particularisation, which maps the upper-scale model results into a smaller number and homogenisation which does the inverse way and analysed the accuracy of this approach.

Multiscale modeling of light-harvesting systems based on rhodamine B aggregates

Rhodamine B (RB) has been successfully exploited in the synthesis of light harvesting systems, but since RB is prone to form dimers acting as quenchers for the fluorescence, high energy transfer efficiencies can be reached only when using bulky and hydrophobic counterions acting as spacers between RBs. In this PhD thesis, a multiscale theoretical study aimed at providing insights into the structural, photophysical and optical properties of RB and its aggregates is presented. At the macroscopic level (no atomistic details) a phenomenological model describing the fluorescence decay of RB networks in presence of both quenching from dimers and exciton-exciton annihiliation is presented and analysed, showing that the quenching from dimers affects the decay only at long times, a feature that can be exploited in global fitting analysis to determine relevant chemical and photophysical information. At the mesoscopic level (atomistic details but no electronic structure) the RB aggregation in water in presence of different counterions is studied with molecular dynamics (MD) simulations. A new force field has been parametrized for describing the RB flexibility and the RB-RB interaction driving the dimerization. Simulations correctly predict the RB/counterion aggregation only in presence of bulky and hydrophobic counterion and its ability to prevent the dimerization. Finally, at the microscopic level, DFT calculations are performed to demonstrate the spacing action of bulky counterions, but standard TDDFT calculations are showed to fail in correctly describing the excited states of RB and its dimers. Moreover, also standard procedures proposed in literature for obtaining ad hoc functionals are showed to not work properly. A detailed analysis on the effect of the exact exchange shows that its short-range contribution is the crucial quantity for ameliorating results, and a new functional containing a proper amount of such an exchange is proposed and successfully tested.

Fat Substitutes In Processing Of Sausages Using Piramutaba Waste.

The aim of this study was to evaluate fat substitute in processing of sausages prepared with surimi of waste from piramutaba filleting. The formulation ingredients were mixed with the fat substitutes added according to a fractional planning 2(4-1), where the independent variables, manioc starch (Ms), hydrogenated soy fat (F), texturized soybean protein (Tsp) and carrageenan (Cg) were evaluated on the responses of pH, texture (Tx), raw batter stability (RBS) and water holding capacity (WHC) of the sausage. Fat substitutes were evaluated in 11 formulations and the results showed that the greatest effects on the responses were found to Ms, F and Cg, being eliminated from the formulation Tsp. To find the best formulation for processing piramutaba sausage was made a complete factorial planning of 2(3) to evaluate the concentrations of fat substitutes in an enlarged range. The optimum condition found for fat substitutes in the sausages formulation were carrageenan (0.51%), manioc starch (1.45%) and fat (1.2%).

Preference Mapping Of Dulce De Leche Commercialized In Brazilian Markets.

Dulce de leche samples available in the Brazilian market were submitted to sensory profiling by quantitative descriptive analysis and acceptance test, as well sensory evaluation using the just-about-right scale and purchase intent. External preference mapping and the ideal sensory characteristics of dulce de leche were determined. The results were also evaluated by principal component analysis, hierarchical cluster analysis, partial least squares regression, artificial neural networks, and logistic regression. Overall, significant product acceptance was related to intermediate scores of the sensory attributes in the descriptive test, and this trend was observed even after consumer segmentation. The results obtained by sensometric techniques showed that optimizing an ideal dulce de leche from the sensory standpoint is a multidimensional process, with necessary adjustments on the appearance, aroma, taste, and texture attributes of the product for better consumer acceptance and purchase. The optimum dulce de leche was characterized by high scores for the attributes sweet taste, caramel taste, brightness, color, and caramel aroma in accordance with the preference mapping findings. In industrial terms, this means changing the parameters used in the thermal treatment and quantitative changes in the ingredients used in formulations.

Amostragem e variabilidade espacial de atributos químicos do solo em área de vegetação natural em regeneração

The objectives of this work was to estimate the number of soil subsamples considering the classical statistics and geostatistics and determine the spatial variability of soil fertility attributes of an Ultisol, with clay texture, in an area of regenerating natural vegetation in Alegre - ES. Soil samples were collected in a depth of 0.0-0.2 m, at the crossing points of a regular grid, comprising a total of 64 points located at 10 m-intervals. The area presented low fertility soil. Considering a variation of 5% around the mean in the classic statistics, it is necessary a larger number of samples in relation to geostatistics. All the chemical attributes showed moderate to high spatial dependence, except for the effective cation exchange capacity (CECe), which showed pure nugget effect. The spherical semivariogram model gave the best fit to the data. Isoline maps allowed visualizing the differentiated spatial distribution of the contents of soil chemical attributes.

Influência do processo de secagem na qualidade do cogumelo shiitake

Edible mushroom are highly perishable foods. Drying is an alternative to provide safe storage. In this work, the effects of some drying parameters on the quality of Shiitake mushroom were investigated: geometry of the raw material (whole and sliced), drying temperature (50 °C and 70 ºC) and final moisture content (5% and 15% wb). Experimental kinetics of drying was built and color and texture analyses were done in fresh and in rehydrated dried product. The effect of parameters was evaluated by analysis of variance and test of multiple comparisons. Drying kinetics showed that drying happened in falling-rate period and sliced mushroom dried at 70 ºC required lesser drying time than other treatments. Mushroom dried at 70 ºC showed less darkening. Drying time affected mushroom quality, evaluated by great hardness, gummosis and darkening.

Utilização de 1-metilciclopropeno e resfriamento rápido na conservação de pêssegos

Postharvest losses vary among the different vegetable products. However, among fruits and vegetables the losses generally range from 30% to 50%. Thus, this paper aimed the application of 1-methylcycloprene (1-MCP) and fast cooling with forced air (PC) on peaches, in order to estimate their effects in the ripening process of this fruit. Physiological analyses were performed, such as loss of fresh mass, firmness, pH, titratable acidity, soluble solids, ratio and CO2 production, as well as sensorial analyses such as color, texture and flavor. The experiment was divided in two phases. In the first one, concentrations of 30, 60, and 90 nL/L 1-MCP, applied at 0 ºC and 20 ºC, were tested. The fruits treated without 1-MCP were denominated control for both temperatures studied. The second phase was composed by the following treatments: cold storage (CS) or control, cooling with forced air (CFA), cooling with forced air followed by 1-MCP application (CFA + 1-MCP) and 1-MCP application (1-MCP). Among these, the CFA + 1-MCP treatment provided more firmness of the fruits in comparison to the control fruits. The respiratory rate of peaches under CFA and CFA + 1-MCP treatments decreased in comparison to the control fruit respiratory rates.

Avaliação de índices de firmeza para abacaxi minimamente processado em fatias tratadas com soluções de sais de cálcio

Fresh-cut sliced fruits and vegetables are ready to eat immediately and their sensorial characteristics should be similar to fresh product. Although most of the studies in this area are focused on vegetables, there is a great market potential for fresh-cut sliced fruits, mainly for those which exhibit some commercialization or preparation difficulties such as pineapple. The objective of this work was to evaluate the effect of 1% and 3% concentrations of calcium salts (chloride, sulphate and lactate) on pH, total soluble solids and firmness values of minimally processed pineapple slices. Two types of indenters and three firmness indexes were investigated aiming to identify the best index. Results showed that calcium sulphate 3% kept average firmness index up to 44.45% higher than the index value of the control. Even though both indenters exhibited similar variability the cylindrical one was able to point out more differences between control and treatments than the cylindrical borer indenter.

Caracterização morfológica das sementes e plântulas de seis espécies invasoras do gênero Solanum L

Morphological caracterization of the seeds and seedlings of six weed especies of the genus Solanum L. The seeds of the genus Solanum are very similar, however, the association of their external characteristics with the anatomical features, such as hilum shape, the texture and the type of the seed coat sculptures, as well as the curved (circulated or coiled) shape of the embryo, are parameters of great importance in the taxonomical identification at the species level. It is are presented the morphological descriptions of the genus Solanum and a more detailed description of each studied species in terms of seed and seedling structures, including illustrations and taxonomical keys for the identification of Solanum aculeatissimum Jacq., S. americanum Mill., S. ciliatum Lam., S. sisymbriifolium Lam., S. sordidum Sendt. e S. viarum Dunal. There are also indications of the common names, the type of reproduction and dispersion, the crops in which the species is considered as a weed and the agricultural seeds in which it is found as a weed seed.

Variabilidade espacial da textura de um latossolo sob cultivo de citros

Relief influences soil texture variability, since it contributes to the time of exposition of the materials to weathering factors. Our work was carried out in the city of Gavião Peixoto (SP), with the objective of characterizing the spatial variability of texture of a dystrophic Red Latosol cultivated with citrus. The hillside was divided into three segments: top, stocking lean and inferior lean. Soil samples were collected in a grid with regular intervals of 50 m, at the depths of 0.0-0.2 m and 0.6-0.8 m, comprising a total of 332 points in an area of 83.5 ha. The data were submitted to descriptive and geostatistics analyses (semivariogram modeling and kriging maps). The spatial behavior of the texture of oxisols is directly related to the relief forms in this study, which controls the direction of surface and subsurface water flows. The concept of homogeneity of clay distribution in the Oxisol profile is a piece of information that can be adjusted by knowing the spatial pattern of this distribution in different relief forms.

CARACTERÍSTICAS DE QUALIDADE DO CONTRAFILÉ (m. L. dorsi) DE TOUROS JOVENS DA RAÇA NELORE

Quality traits of boneless rib cut (L. dorsi muscle) from Nelore young bulls. To study the meat quality traits of Nelore breed young bulls, and the effect of age (690-780 days) on them, 113 animals were slaughtered after 109 days of intensive feeding with 20% concentrate and 80% roughage. All the carcasses were graded at the slaughter floor by the Federal Inspection and chilled for 24 hours (Tinitial=5°C, Tfinal=2°C). Fifty one half carcasses (right side), type B - B R A S I L `s grading system - from animals of 23 to 26 months were boned and separated into commercial cuts. Two steaks (2.5cm thick) were removed from each boneless rib cut (m. L. dorsi), vacuum packaged and aged for 7 days (0-2°C). The pH varied from 5.44 to 5.83 and only two samples had pH ³ 5.70. The L* (brightness) average value was 34.85. The water and fat content were 75.65% and 1.71%, respectively. The average WB shear force was 6.70kg, and it was not affected by age (690-734 days), but presented a trend (t test, p=0.22) for increasing values between 735 and 780 days. Animal age did not affect other quality traits (t test, p>0.20). It was concluded that the rib cut from Nelore young bulls may not have a good acceptability in exigent markets, and that carcasses graded B, presumed to be the best grade, do not necessarily present the best meat quality characteristics.

Avaliação do amaciamento de carne bovina de dianteiro (Triceps brachii) pelos métodos de maturação, estimulação elétrica, injeção de ácidos e tenderização mecânica

Twenty-two Triceps brachii muscle obtained from 11 cows aged 3 and 4 years , killed in an experimental slaughter plant, were submitted to mechanical tenderization, injection with acetic acid 0,1M and lactic acid 0,2M, ageing for 9 and 14 days and electrical stimulation (250v - 60Hz - 90s), some of them were reserved as a control group, without treatment. The 14 days ageing time presented 21% of increase in subjective tenderness and 12% of reduction in shear force, these values were similar to the electrical stimulated meat. However the injection with acids and the ageing time 9 days did not present significant effect in the texture. Although the shear force values of mechanical tenderized meat was the shortest among all treatments, suspect of superestimation because of the fractures plan created by this process. Another analyses were carried out: pH reduction curve, R value; colour analysis; weight losses by cooking and by treatment; and microbiological analysis.

Caracterização sensorial de amêndoas de castanha-de-caju fritas e salgadas

Shelled, roasted and salted cashew nut kernels were packaged in three different flexible materials (PP/PE= polypropylene / polyethylene; PETmet/PE= metallized polyethylene terephthalate / polyethylene; PET/Al/LDPE= polyethylene terephthalate / aluminum foil / low density polyethylene ), with different barrier properties. Kernels were stored for one year at 30° C and 80% relative humidity. Quantitative descriptive sensory analysis (QDA) were performed at the end of storage time. Descriptive terms obtained for kernels characterization were brown color, color uniformity and rugosity for appearance; toasted kernel, sweet, old and rancidity for odor; toasted kernel, sweet, old rancidity, salt and bitter for taste, crispness for texture. QDA showed that factors responsible for sensory quality decrease, after one year storage, were increase in old aroma and taste, increase in rancidity aroma and taste, decrease in roasted kernel aroma and taste, and decrease of crispness. Sensory quality decrease was higher in kernels packaged in PP/PE.