Extração supercrítica do óleo de linhaça: construção do extrator, estudo de parâmetros de processo, avaliação química e antioxidante do produto

The aim of the present study was to extract vegetable oil from brown linseed (Linum usitatissimum L.), determine fatty acid levels, the antioxidant capacity of the extracted oil and perform a rapid economic assessment of the SFE process in the manufacture of oil. The experiments were conducted in a test bench extractor capable of operating with carbon dioxide and co-solvents, obeying 23 factorial planning with central point in triplicate, and having process yield as response variable and pressure, temperature and percentage of cosolvent as independent variables. The yield (mass of extracted oil/mass of raw material used) ranged from 2.2% to 28.8%, with the best results obtained at 250 bar and 50ºC, using 5% (v/v) ethanol co-solvent. The influence of the variables on extraction kinetics and on the composition of the linseed oil obtained was investigated. The extraction kinetic curves obtained were based on different mathematical models available in the literature. The Martínez et al. (2003) model and the Simple Single Plate (SSP) model discussed by Gaspar et al. (2003) represented the experimental data with the lowest mean square errors (MSE). A manufacturing cost of US$17.85/kgoil was estimated for the production of linseed oil using TECANALYSIS software and the Rosa and Meireles method (2005). To establish comparisons with SFE, conventional extraction tests were conducted with a Soxhlet device using petroleum ether. These tests obtained mean yields of 35.2% for an extraction time of 5h. All the oil samples were sterilized and characterized in terms of their composition in fatty acids (FA) using gas chromatography. The main fatty acids detected were: palmitic (C16:0), stearic (C18:0), oleic (C18:1), linoleic (C18:2n-6) and α-linolenic (C18:3n-3). The FA contents obtained with Soxhlet dif ered from those obtained with SFE, with higher percentages of saturated and monounsaturated FA with the Soxhlet technique using petroleum ether. With respect to α-linolenic content (main component of linseed oil) in the samples, SFE performed better than Soxhlet extraction, obtaining percentages between 51.18% and 52.71%, whereas with Soxhlet extraction it was 47.84%. The antioxidant activity of the oil was assessed in the β-carotene/linoleic acid system. The percentages of inhibition of the oxidative process reached 22.11% for the SFE oil, but only 6.09% for commercial oil (cold pressing), suggesting that the SFE technique better preserves the phenolic compounds present in the seed, which are likely responsible for the antioxidant nature of the oil. In vitro tests with the sample displaying the best antioxidant response were conducted in rat liver homogenate to investigate the inhibition of spontaneous lipid peroxidation or autooxidation of biological tissue. Linseed oil proved to be more efficient than fish oil (used as standard) in decreasing lipid peroxidation in the liver tissue of Wistar rats, yielding similar results to those obtained with the use of BHT (synthetic antioxidant). Inhibitory capacity may be explained by the presence of phenolic compounds with antioxidant activity in the linseed oil. The results obtained indicate the need for more detailed studies, given the importance of linseed oil as one of the greatest sources of ω3 among vegetable oils

Influência do teor e granulometria da calcita e da temperatura de sinterização no desenvolvimento de massas cerâmicas para revestimento poroso(BIII)

This work aims at studying the influence of the concentration of calcite, its grain size and sintering temperature to obtain porous coating formulations that meet the design specifications. The experiments involved the physical-chemical and mineralogical caracterization of the raw materials, and mechanical tests on specimens dried and sintered, performing a planning mixture and factorial experiment, using the response surface methodology. The ceramic bodies studied were prepared by dry process, characterized, placed in conformity by uniaxial pressing and sintered at temperatures of 940 º C, 1000ºC, 1060ºC, 1120°C and 1180°C using a fast-firing cycle. The crystalline phases formed during sintering at temperatures under study, revealed the presence of anorthite and wolastonite, and quartz-phase remaining. These phases were mainly responsible for the physical and mechanical properties of the sintered especimens. The results shown that as increases the participation of carbonate in the composition of ceramic bodies there is an increase of water absorption and a slight reduction in linear shrinkage for all sintering temperatures. As for the mechanical strength it was observed that it tended to decrease for sintering at temperatures between 940 ° C and 1060 ° C and to increase for sintering at temperatures above 1060 ° C occurring with greater intensity for compositions with higher content of calcite. The resistence decreased with increasing participation of quartz in all sintering temperatures. The decrease in grain size of calcite caused a slight increase in water absorption for formulation with the same concentration of carbonate, remaining virtually unchanged the results of linear shrinkage and mechanical strength. In conclusion, porous ceramic coating (BIII) can be obtained using high concentrations of calcite and keeping the properties required in technical standards and that the particle size of calcite can be used as tuning parameter for the properties of ceramic products.

GREEN MACHINING ORIENTED TO DIMINISH DENSITY GRADIENT FOR MINIMIZATION of DISTORTION IN ADVANCED CERAMICS

After sintering advanced ceramics, there are invariably distortions, caused in large part by the heterogeneous distribution of density gradients along the compacted piece. To correct distortions, machining is generally used to manufacture pieces within dimensional and geometric tolerances. Hence, narrow material removal limit conditions are applied, which minimize the generation of damage. Another alternative is machining the compacted piece before sintering, called the green ceramic stage, which allows machining without damage to mechanical strength. Since the greatest concentration of density gradients is located in the outer-most layers of the compacted piece, this study investigated the removal of different allowance values by means of green machining. The output variables are distortion after sintering, tool wear, cutting force, and the surface roughness of the green ceramics and the sintered ones. The following results have been noted: less distortion is verified in the sintered piece after 1mm allowance removal; and the higher the tool wear the worse the surface roughness of both green and sintered pieces.

Evaluation of Electrical Properties of Lap Joints for BSCCO and YBCO Tapes

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Structural Evaluation of Mechanically Alloyed and Heat-Treated Ti-25at-%Si Powders

This work discusses on the structural evaluation of mechanically alloyed and heat-treated Ti-25at%Si powders. The milling process was conducted in a planetary ball mill using stainless steel balls/vials, 200 rpm and ball-to-powder weight ratio of 5:1, whereas the heat treatment was conducted under Ar atmosphere at 1100 C for 4 h. Samples were characterized by X-ray diffraction, differential scanning calorimetry, scanning electron microscopy and energy dispersive spectrometry. The Si peaks disappeared after milling for 30h, indicating that the Si atoms were dissolved into the Ti lattice in order to form an extended solid solution. The Ti peaks were broadened and their intensities reduced for longer milling times whereas a halo was formed in Ti-25Si powders milled for 200h suggesting that an amorphous structure was achieved. The crystallite size was decreased with increasing milling times. A large Ti3Si amount was found in mechanically alloyed Ti-25at%Si powders after heating at 1100 degrees C for 4h.

Effect of high pressure in the Li2O-2SiO(2) crystallization

The aim of this work was to investigate the effect of previous treatments at high pressures on the crystallization kinetics of monolithic samples of a Li2O-2SiO(2) (LS2) glass. The glass transition temperature (T-g) and the temperature of the onset of crystallization (T-p) obtained by differential thermal analyses (DTA) were measured for LS2 glass samples submitted to isostatic pressures ranging from 2.5 to 7.7 GPa during 5 min at room temperature. The observed systematic changes in T-g and T-p were probably related to the cracks induced by high pressure inside the monolithic samples and in its surface. Away from the cracks, the nucleation density slightly decreased as a function of pressure but along the cracks, the nucleation density was significantly higher. (C) 2010 Elsevier B.V. All rights reserved.

Structural Evaluation of Mechanically Alloyed (67-x)Ti-xZr-22Si-11B Powders

The present work reports on the structural evaluation of mechanically alloyed Ti-xZr-22Si-11B (x = 5, 7, 10, 15 and 20 at-%) powders. Milled powders and hot-pressed alloys were characterized by X-ray diffraction, electron scanning microscopy, and electron dispersive spectrometry. The Si and B atoms were preferentially dissolved into the Ti and Zr lattices during ball milling of Ti-xZr-22Si-11B (x = 7, 10, 15 and 20 at-%) powders, and extended solid solutions were achieved. The displacement of Ti peaks was more pronounced to the direction of lower diffraction angles with increasing Zr amounts in mechanically alloyed Ti-Zr-Si-B powders, indicating that the Zr atoms were also dissolved into the Ti lattice.

Surface Corrosion of Ti-16Si-4B Powder Alloy Implanted With Nitrogen by Plasma-Based Technique

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

A new route to obtain PVDF/PANI conducting blends

Electrically conductive poly(vinylidene fluoride)(PVDF) - polyaniline blends of different composition were synthesized by chemical polymerization of aniline in a mixture of PVDF and dimethylformamide (DMF) and studied by electrical conductivity measurement, UV-Vis-NIR and FTIR spectroscopy. The samples were obtained as flexible films by pressing the powder at 180 degrees C for 5 min. The electrical conductivity showed a great dependence on the syntheses parameters. The higher value of the electrical conductivity was obtained for the oxidant/aniline molar ratio equal to 1 and p-toluenesulfonic acid-TSA/aniline ratio between 3 and 6. UV-Vis-NIR and FTIR spectra of the blend are similar to the doped PANI, indicating that the PANI is responsible for the high electrical conductivity of the blend. The electrical conductivity of blend proved to be stable as a function of temperature decreasing about one order at temperature of 100 degrees C. The route used to obtain the polymer blend showed to be a suitable alternative in order to obtain PVDF/PANI-TSA blends with high electrical conductivity. (c) 2006 Elsevier Ltd. All rights reserved.

Compósitos de borracha natural com polianilina

Compósitos de borracha natural (Hevea brasiliensis)-BN/polianilina - PANI, com diferentes composições foram obtidos através da polimerização por emulsão do monômero anilina na presença da BN e do ácido dodecilbenzeno sulfônico (DBSA). Filmes finos e homogêneos foram obtidos por prensagem a quente. Os compósitos foram caracterizados por condutividade elétrica, FTIR, UV-vis-NIR, DSC e difração de raios X. Compósito com condutividade elétrica cerca de 14 ordens de grandeza maior que a BN foi obtido. Este alto valor de condutividade é atribuído à formação da PANI no estado dopado no compósito, que foi verificado através das técnicas de UV-vis-NIR e FTIR. Os resultados obtidos com a técnica de DSC e difratometria de raios X indicaram que os polímeros são imiscíveis e que a presença da borracha não altera significantemente a fase cristalina da PANI-DBSA no compósito.

Pyroelectric composite film for X-ray intensity detection

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of the sintering conditions on the electrical properties of Nd(3+) modified PLZT ceramics

The effect of the sintering method on the microstructural and electrical properties of (Pb(0.89)Nd(0.02)La(0.09))(Zr(0.65)Ti(0.35))O(3) (PNLZT) ceramics was studied by impedance spectroscopy. Structural and microstructural analyses were performed using x-ray and scanning electron microscopy techniques. Two different sintering routes were employed: the conventional and the hot-pressing sintering methods. The impedance analysis provided a convincing evidence for the existence of both grain (g) and grain boundary (gb) contributions to the conduction process. An equivalent circuit for the impedance behaviour has been proposed and discussed. The variation in the sintering method produces significant changes in the grain and grain boundary conductivities. For the grain effect, the main conduction mechanism has been associated with oxygen vacancy migration. Otherwise, for grain boundary conductivity the impedance behaviour has been discussed in terms of the brick-layer and the constriction resistance models (BLM and CRM, respectively).

Piezo and Dielectric Properties of PHB-PZT Composite

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Photopyroelectric response of PTCa/PEEK composite

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Silenciosas e silenciadas: descortinando as violências contra a mulher no cotidiano da prostituição em Natal-RN

The prostitution is known as the world's oldest "profession", according to some historians, "the contemporary civilization itself." However, to refer it that way, we can systematically emptying it of expressions of violence that permeate. Furthermore, this statement tries to legitimize prostitution as a practical historically related to the natural condition of women. The main objective of the research is to examine how the activity prostitucional potentiates in different forms of violence in everyday development of prostitution in the city of Natal. Accordingly, the spot of the categories of gender relations and patriarchal violence against women, refute the thesis advocated by much of feminist studies on of prostitution as an expression of autonomy of women and overcoming the patriarchal order of gender. Procedures as set methodological quali-quantitative approach, guided by the method historicalmaterialist dialectic that allows us to apprehend the object of study beyond their immediate, unmasking its contradictions. We conducted nine interviews with prostitutes belonging to the classes of People who develop the activities in the streets and prostitutes Natals` cabarets. We hand with the systematic observation activities promoted by the Association of Prostitutes in Rio Grande do Norte ASPRORN, as the visits to cabarets, as well as participation in seminars held by this entity, at which establish contacts with informants-c which have facilitated access to interviewed. We note that the economic dimension is the factor determinant for their inclusion in prostitution, all to recognize as who found an alternative for survival, since most do not has no professional training and education. Another issue important to be emphasized concerns the areas where unhealthy develop programs which by itself is characterized as a denial of rights, expressed in the socioeconomic inequality that are subject. As the expressions of violence in their daily lives, the main forms identified were the physical and social, however, there is a trend in naturalizes them, the secondary-over other issues identified as most pressing, such as not service payment by the customers. The determinants of violence identified by respondents were assigned to the woman, or is its boldness. We also, the omission of the State in the issue of prostitution, mainly embodied in absence of public policies directed to sexual rights and reproductive and generation of employment and income. Regarding the regulation of prostitution, the majority of the interviewees is contrary, arguing that exacerbate the stigma in this practice