Eliria Maria de Jesus Agnolon Pallone

Development of solid lipid microparticles loaded with a proanthocyanidin-rich cinnamon extract (Cinnamomum zeylanicum): Potential for increasing antioxidant content in functional foods for diabetic population

Cinnamon proanthocyanidins play an important role on the attenuation of complications associated to diabetes, but the daily ingestion of these compounds is not always satisfactory due to several aspects such as low stability and unpleasant taste. Thus, in the present study, a proanthocyanidin-rich cinnamon extract (Cinnamomum zeylanicum) was incorporated into solid lipid microparticles (SLMs) by spray chilling technique using vegetable fat as carrier. The microparticles were characterized with regard to their physical and chemical properties, morphology, proanthocyanidin stability and sensory properties. SLMs were spherical with a unimodal size distribution between 60 and 130μm, and proanthocyanidins were highly stable in SLM stored for up to 90days at 5, 25 and 37°C. Moreover, SLMs were able to mask the bitter taste and astringent sensation of proanthocyanidins and other polyphenols from cinnamon extract. Taken together, these results show the potential of SLM loaded with cinnamon proanthocyanidins for improving functional properties in new foods.

Evaluation of the release profile, stability and antioxidant activity of a proanthocyanidin-rich cinnamon (Cinnamomum zeylanicum) extract co-encapsulated with α-tocopherol by spray chilling

Cinnamon has many health improving compounds such as proanthocyanidins, which also have potential for the prevention of damages caused by diabetes. Similarly, α-tocopherol is a natural antioxidant with important role on protection of fatty acids in membranes and lipoproteins. However, the addition of antioxidants in food may result in interaction with food matrix, low stability and unpleasant taste. In the present study, a proanthocyanidin-rich cinnamon extract (PRCE) (Cinnamomum zeylanicum) was co-encapsulated with α-tocopherol into solid lipid microparticles (SLMs) by spray chilling. The microparticles were characterized with regard to the physical and chemical properties, morphology, proanthocyanidin stability and release profile. SLMs were spherical with an average diameter of ca. 80μm. Proanthocyanidins were highly stable in SLMs stored for up to 90days at 5, 25 and 37°C. Moreover, SLMs gradually released proanthocyanidins in simulated gastrointestinal fluids by a diffusional process, following a Korsmeyer-Peppas kinetic. Analyses of the antioxidant compounds indicated that PRCE components exhibited a higher scavenging capacity against reactive oxygen species (ROS) and reactive nitrogen species (RNS). Thus, the SLMs produced in the present study have potential for application in the development of new functional foods and nutraceuticals, also providing an alternative for the controlled release of proanthocyanidins and α-tocopherol into the intestine.

Mechanisms of Microstructure Control in Conventional Sintering

The manner and mechanisms involved on the sintering process are essential investigation to achieve the required microstructure and final properties in solids. During the conventional sintering of a compacted powder, densification and grain growth occur simultaneously through atomic diffusion mechanisms. Many researchers have been working on reducing the grain size below 1 μm aiming to improve some properties, such as strength, toughness and wear resistance in ceramics (Greer, 1998; Inoue & Masumoto, 1993; Morris, 1998). In order to obtain ultra-fine ceramic microstructures, nanocrystalline powders can be used. Although the sinterability of nanoparticles is superior to that of fine particles due to the higher sintering stress, densification of these powders is often accompanied by grain growth (Suryanarayana, 1995).

Effects of the Pin-on-Disc Parameters on the Wear of Alumina

There is a growing interest in the application of ceramic as high wear resistance materials due to the unique properties. Although brittleness and low toughness, recent improvements in alumina processing have lessen this restrictions and suggest improvements in wear resistance which in turn have driven some research on this. Since a direct comparison between the many published works regarding this wear improvement is complicated due to the fact that wear resistance is a response of the microstructure, material and testing condition, the work herein presented aims to first do a literature review on the main parameters to be controlled in a pin-on-disc apparatus on the wear of alumina and then discuss preliminary test results and analyze the influence of critical parameters as load and sliding speed in a pin-on-disc wear test in a dense and sub micrometer grain size alumina.

Preparação e caracterização de catalisadores ácidos de zircônia sulfatada para aplicação na esterificação do óleo de algodão

This work aimed to produce zirconia by combustion synthesis, to analyze the structure and morphology comparatively with a commercial monoclinic ZrO2, as well as, to investigate the sulfation, aiming to obtain acid catalysts for its use in the esterification of cotton oil for biodiesel. The samples were characterized by X-ray diffraction, scanning electron microscopy (SEM), specific surface area by BET method, infrared spectroscopy (FTIR), thermal analysis (TG/DrTG/DTA), granulometric distribution, pH and chromatography. The synthesized sample evidenced the formation of the monoclinic phase with traces of the orthorhombic phase, while in the commercial sample only the monoclinic phase was observed. In the sulfation process, traces of the tetragonal phase, typical of sulfated zirconia, were observed with the presence of the monoclinic phase in the two samples. With the impregnation of the sulfate ion on the surface of the samples, an increase in the particle size was observed, as seen in the characterization of BET, granulometric distribution and SEM, which also indicated a homogeneous morphology consisting of fine particles of approximately spherical shape for both samples. The chromatography indicated conversion of 65.5 and 91.8% in methyl esters to the synthesized and commercial SO4 2-/ZrO2, respectively. The results indicated that the sulfation increased the acidity, which was evidenced by the decrease in the pH, ranging from 5.12 to 2.65, which contributed significantly to the increase of the conversion, indicating that the SO4 2-/ZrO2 is a promising catalyst in the esterification.

Microstructural Evolution of Alumina-Zirconia Nanocomposites

Ceramic materials have limited use due to their brittleness. The inclusion of nanosized particles in a ceramic matrix, which are called nanocomposites, and ceramic processing control by controlling the grain size and densification can aid in obtaining ceramic products of greater strength and toughness. Studies showed that the zirconia nanoinclusions in the matrix of alumina favor an increase in mechanical properties by inhibiting the grain growth of the matrix and not by the mechanism of the transformation toughening phase of zirconia. In this work, the microstructural evolution of alumina nanocomposites containing 15% by volume of nanometric zirconia was studied. From the results it was possible to understand the sintering process of these nanocomposites.

PAINEL AGLOMERADO HÍBRIDO DE CASCA DE AMENDOIM REFORÇADO COM PARTÍCULAS DE MADEIRA ITAÚBA

In this paper, it was considered the study of the potential use of peanut hulls and wood particles of itauba (Mezilaurus itauba) species in order to add value to these materials through the manufacture of hybrid particle board in order to compare the physical and mechanical performances as well as durability. For these procedures, it was used the bi-component polyurethane resin based on castor beans (mammon) oil and urea-formaldehyde. The product quality was evaluated based on the requirements of the standards NBR 14.810:2006 APA PRP and 108, through physico-mechanical and microstructural durability. The results indicate that the incorporation of wood particles warrants an increase in physical-mechanical properties of the particleboard manufactured with peanut hulls, the polyurethane resin based on castor oil was effective as a particle adhesive binder and the durability assay indicated that the material should be used under conditions of low exposure to moisture.

Densification of Reactive Milled Al2O3-TiC Composite Powders

The synthesis of Al 2 O 3 - TiC composite powder can be achieved by reactive milling of powder mixtures of TiO 2 , Al and C. In this case the reactive milling occurs through a sudden highly exothermic self-sustaining reaction started after a certain milling time. Due to the high temperatures reached during the reaction, the products are formed as strong agglomerates. For the synthesis of the Al 2 O 3 + TiC, probably due the high melting point of the reaction products, particularly of the TiC, these agglomerates are formed by crystallites in the nanometric range. In the present work, Al 2 O 3 - TiC composite was synthesized by reactive milling in a shaker/mill apparatus, followed by a deagglomeration processing. The products of reactive milling were mixed with a commercial ultra-fine alumina powder to produce alumina matrix composites with 5 wt% of TiC. The powder densification was performed by hot pressing and by pressureless sintering between 1400 and 1600 °C. We report on the microstructure characterization of the dense TiC+Al 2 O 3 composites by SEM and TEM. It was observed that TiC is dispersed in the alumina matrix microstructure as both agglomerated inclusions and also dispersed nanometric inclusions. Vickers Hardness measurements of the sintered composites indicated values of about 13.0GPa.

Microstructural and Mechanical Properties of Al2O3/HAp Composites for Use as Bone Substitute Material

This work involved the development of alumina/hydroxyapatite (Al2O3/HAp) composites for use as bone graft material in maxillofacial reconstruction. The effect of introducing 20 and 30 wt% of hydroxyapatite into the alumina matrix was also investigated. The composites were produced from hydroxyapatite synthesized by the precipitation method, using commercial alumina as a matrix. Samples of the composite material were compacted under 260 MPa of isostatic pressure, followed by sintering at 1200°C/2h and characterization by X-ray diffraction (XRD), scanning electron microscopy (SEM), and diametral compression. The XRD results confirmed the presence of Al2O3 and Ca10(PO4)6(OH)2 – HAp crystalline phases in all composites. The addition of HAp to the alumina matrix inhibited alumina grain growth, reducing intergranular porosity and thus promoting greater densification and mechanical strength of the composites.

Surface modification using the biomimetic method in alumina-zirconia porous ceramics obtained by the replica method: SURFACE MODIFICATION USING THE BIOMIMETIC METHOD

The modification of biomaterials approved by the Food and Drug Administration could be an alternative to reduce the period of use in humans. Porous bioceramics are widely used as support structures for bone formation and repair. This composite has essential characteristics for an implant, including good mechanical properties, high chemical stability, biocompatibility and adequate aesthetic appearance. Here, three-dimensional porous scaffolds of Al2 O3 containing 5% by volume of ZrO2 were produced by the replica method. These scaffolds had their surfaces chemically treated with phosphoric acid and were coated with calcium phosphate using the biomimetic method simulated body fluid (SBF, 5×) for 14 days. The scaffolds, before and after biomimetic coating, were characterized mechanically, morphologically and structurally by axial compression tests, scanning electron microscopy, microtomography, apparent porosity, X-ray diffractometry, near-infrared spectroscopy, inductively coupled plasma optical emission spectroscopy, energy dispersive X-ray spectroscopy and reactivity. The in vitro cell viability and formation of mineralization nodules were used to identify the potential for bone regeneration. The produced scaffols after immersion in SBF were able to induce the nodules formation. These characteristics are advantaged by the formation of different phases of calcium phosphates on the material surface in a reduced incubation period.