The objective of this study was to evaluate the reduction on the levels of mycotoxins in wheat products and by-products: deoxynivalenol (DON) in whole wheat flour, wheat bran and the efluent from wet milling of wheat flour, and zearalenone (ZEN) in wheat bran. Firstly, the reduction of DON contamination was studied on whole wheat flour, naturaly contaminated, and considering different moisture levels, as well as in wet milling effluent of wheat flour. Further, the impact of the ozonation process on the rheological properties of the processed flour was evaluated. Secondly, the wheat bran naturally co-contaminated with DON and ZEN was studied, considering the degradation of both mycotoxins and the impact of the ozonation process on the bran phenolic compound content and on the antioxidant capacity. The DON degradation in the whole wheat flour increased with both processing time and moisture content. By changing these process parameters, it was possible to obtain products in accordance with the legal limits of Brazil and the European Union, even starting with concentration 2-4 times higher than the legal limits. However, the rheological properties of the whole wheat flour were affected by the process, probably due to protein modifications. The DON concentration on the wet milling effluent was linearly reduced by the ozonation. In wheat bran naturally contaminated and in its equilibrium moisture, the ozonation reduced both DON and ZEN contamination. The degradation of ZEN was higher and faster than the degradation of DON, which could be explained by their molecular structures. It was also observed that the ozonation process did not negatively affect the phenolic compounds and the antioxidant capacity, which is high desirable from a nutritional point of view. Consequently, this work concludes that the ozonation process was effective in reducing DON and ZEN in different wheat products and efluent. It is noteworthy that the results obtained are promising for future studies and to elucidate the mechanism of action of ozone on mycotoxins and constituents of food. / O objetivo deste estudo foi avaliar a redução nos níveis de micotoxinas em produtos e subprodutos de trigo: desoxinivalenol (DON) em farinha de trigo integral, farelo de trigo e efluente de moagem da farinha de trigo e zearalenona (ZEA) em farelo de trigo. No primeiro momento, a redução da contaminação por DON foi estudada em farinha de trigo integral, naturalmente contaminada e considerando diferentes níveis de umidade, bem como no efluente de moagem úmida da farinha. Além disso, o impacto do processo de ozonização nas propriedades reológicas da farinha processada foi avaliado. Em segundo lugar, estudou-se o farelo de trigo naturalmente co-contaminado com DON e ZEA, considerando a degradação de ambas as micotoxinas e o impacto do processo de ozonização no conteúdo do composto fenólico do farelo e na capacidade antioxidante. A degradação de DON na farinha de trigo integral aumentou tanto com o tempo de processamento quanto com o teor de umidade. Ao alterar esses parâmetros de processo, foi possível obter produtos de acordo com os limites legais do Brasil e da União Européia, mesmo com a concentração 2-4 vezes superior aos limites legais. Contudo, as propriedades reológicas da farinha de trigo integral foram afetadas pelo processo, provavelmente devido a modificações de proteínas. A concentração de DON no efluente de moagem úmida foi linearmente reduzida pela ozonização. Em farelo de trigo naturalmente contaminado e em sua umidade de equilíbrio, a ozonização reduziu a contaminação DON e ZEA. A degradação do ZEA foi maior e mais rápida que a degradação do DON, o que poderia ser explicado pelas suas estruturas moleculares. Observou-se também que o processo de ozonização não afetou negativamente os compostos fenólicos e a capacidade antioxidante, o que é altamente desejável do ponto de vista nutricional. Consequentemente, este trabalho conclui que o processo de ozonização foi efetivo na redução de DON e ZEA em diferentes produtos de trigo e efluentes. Vale ressaltar que os resultados obtidos são promissores para futuros estudos e elucidar o mecanismo de ação do ozônio sobre micotoxinas e constituintes dos alimentos.

Probiotic bacteria are live microorganisms, which manifest health benefits in humans. The goal of this work was to characterize rheological properties of probiotic bacteria (Lactobacillus reuteri) formulation in which maltodextrin and sucrose used as excipients. To fulfil the goal, first, thermal, structural and rheological properties of maltodextrin, sucrose solutions and probiotic bacteria slurry were investigated. Probiotic bacteria formulations were prepared by adding probiotic bacteria slurry to maltodextrin and sucrose solutions at different mass fractions. Finally, rheological properties of probiotic bacteria formulations were evaluated. From TGA, the water content of PB slurry including intracellular water found 81%. In DLS, three different types of aggregations of maltodextrin were observed and characteristic size of Probiotic bacteria found 1μm. The optical microscopy results indicate that at the liquid - air interface and in dehydrated state the bacteria are birefringent and arranged in an ordered fashion resembling a nematic phase. Most of the MD, SU and MD+SU solutions show Newtonian behaviour. MD and SU solutions show strong increase of viscosity with increasing concentration. This dependence can be described by using the Spurlin–Martin–Tennent’s model. The viscosities of MD+SU solutions increase with increasing proportion of maltodextrin. The oscillation data of MD and MD+SU solutions can be described by Maxwell model. The viscosities of MD, SU, MD+SU mixed solutions decrease with increasing temperature. This temperature dependency can be described by Arrhenius model of viscosity. At very high concentrations of MD, a deviation from this behaviour is observed. The probiotic bacteria slurry shows shear thinning behaviour at low shear stress and Newtonian behaviour at higher stresses. All probiotic formulations in which probiotic bacteria dispersed in maltodextrin and sucrose solutions show Newtonian behaviour. The viscosities of maltodextrin solutions and MD+SU mixed solutions decrease by addition of probiotic bacteria whereas mixed effects of probiotic bacteria addition on the viscosity of sucrose solutions were observed. The viscosity of probiotic bacteria slurry decreases with increasing temperature, although deviations from this behavior are seen at certain conditions.

We develop a two-fluid model (TFM) for heat transfer in dense non-Brownian suspensions. Specifically, we propose closure relations for the inter-phase heat transfer coefficient and the thermal diffusivity of the particle phase based on calibration against experimental data. The model is then employed to simulate non-isothermal flow in an annular Couette cell. We find that, when the shear rate is controlled by the rotation of the inner cylinder, both the shear and thermal gradients are responsible for particle migration. Within the TFM framework, we identify the origin and functional form of a "thermo-rheological" migration force that rationalizes our observations. Furthermore, we apply our model to flow in eccentric Couette cells. Our simulations reveal that the system's heat transfer coefficient is affected by both the classic shear-induced migration of particles and the newly identified thermo-rheological migration effect. Finally, we employed the proposed computational TFM framework to analyze electronics cooling by forced convection for microchannel cooling. We used a suspensions of high thermal conductivity (Boron Nitride) particles in a 3M Fluorinert FC-43 cooling fluid. Three-dimensional simulations were run to quantify the temperature distributions under uniform heating (5 W) and under hot-spot heating (2 W/cm^2) conditions. A 100 K junction level temperature improvement (enhanced thermal spreading) was seen for hot-spot heating and 15 K was observed for uniform heating, demonstrating the enhanced cooling capabilities of dense particulate suspensions of high-conductivity particles, over a clear FC-43 fluid.

The thesis deals with HDPE modification by crosslinking. In the theoretical part, data available in the literature were reviewed. Modifications of the selected HDPE copolymer grade were carried out in a kneading device Brabender using 25 ml chamber size. After having optimized process conditions, there were performed a series of experiments in dependence on concentration of the initiator. Reological properties of polymer samples were investigated by melt flow indexes measured under different conditions. Changes in crystallinity and melting temperatures were evaluated from DSC heat flow measurements. The samples meeting characteristics supposed were selected for measuring complex viscosity on the Rheometer AR-G2 TA and for testing some mechanical properties on the device Zwick.

Steel corrosion is one of the major distress mechanisms that causes the deterioration of reinforced concrete structures around the world. It is an electrochemical reaction between the reinforcing steel and the surrounding concrete that produces a mass loss of the metal. Through the process of corrosion in reinforced concrete, iron ions get oxidized to form corrosion products (CP). Although multiple experiments and studies have been developed to understand the rheological behavior of corrosion products, this topic stays inconclusive. This work aims to characterize corrosion products at micro-scale in order to trace the progress of the formation of rust, to determine its nature and to analyse its rheological behavior in reinforced concrete. An experimental procedure to produce CP in the laboratory is also presented in this research. In addition, material characterization methods have been used to identify the iron oxide phases present in CP, determine their viscosity and rheological behavior and to study how CP flows in a porous media. In order to identify the different stages in the corrosion process, the CP was analysed at 2, 4, 6 and 8 weeks. The experiments identified four phases of iron oxide for each period. Furthermore, it was found that CP behaves as a shear-thinning slurry and as a result, its viscosity decreases with the applied shear rate. In addition, the damage caused by CP on concrete depends on the w/c ratio of the concrete mix and the exposure time to a corroding environment. The rebar mass loss results show that CP is formed in layers around the rebar, and the flow of each CP layer can differ.

No description available.

Yes / The principal aim of this paper is to investigate the effect of sand grading, surface morphology, and content on the rheological properties—that is, yield stress and plastic viscosity—of fresh mortar. Mortars were produced from four different types of sand at two volumetric cement-sand ratios of 1/0.9 and 1/0.6. Each blend was prepared with five water-cement ratios of 0.60, 0.55, 0.50, 0.45, and 0.40. The rheometer was used to determine yield stress and plastic viscosity parameters of each cement paste and mortar. Test results show that the relative yield stress and plastic viscosity of mortar to cement paste is inversely proportional to the excess paste thickness up to low values, below which the surface texture of sand particles becomes significant.

This study seeks to develop smart hydrogel formulations for injectable controlled drug delivery from Pluronics to enhance patients compliance, decrease side effects, reduce dose and frequency. A biocompatible copolymer, Pluronic F127 was probed as the main ingredient for the injectable systems owing its low gelation concentration and ease of modification the system properties through excipients addition. The matrix properties were studied through a series of thermal, rheological and structural (SAXS/SANS) experiments as a function of concentration and shear rate, covering both static and dynamic environments. It has shown that gelled viscosity (and structure) can be critically controlled by shear rate and the structures recorded do not match those predicted for sheared colloids. Two further Pluronics F68 and F108, were studied showing similar but shifted gelation properties to F127. Effects of additives were studied by introducing different Mw PEGs and a model hydrophobic drug ‘ibuprofen’ to a F127 20% formulation. PEGs addition effects on the system properties and gelation transition were largely dependent on the Mw used in the blend, which became more prominent with increasing chain length. Ibuprofen’s addition has resulted in reduced gelation temperature and smaller hard spheres without having a great effect on the system rheological properties compared to neat gels. Blends containing both additives PEG and ibuprofen exhibited a synergistic effect, where comparisons show that Ibuprofen had the largest effect on the blends lowering gelation boundaries and slightly increasing the size of the hard spheres indicating the necessity of full characterisation of the formulation with any API.

No description available.

No description available.