999 resultados para Biodiesel. Transesterificação. Estabilidade Oxidativa. P-DSC.Rancimat


Relevância:

30.00% 30.00%

Publicador:

Resumo:

A atual demanda por produtos alternativos que substituam os combustíveis fósseis, causadores de alto impacto ambiental negativo, tem fomentado pesquisas em diferentes áreas como o emprego de lipases microbianas como biocatalisadores no setor de energia. Como mais uma forma de busca por tecnologias limpas, há também interesse no aproveitamento de resíduos agroindustriais. Nessa vertente, o Brasil como grande produtor agrícola se destaca na geração de subprodutos como o bagaço de cana-de-açúcar. Uma alternativa mais ecológica para atender a essa demanda é a produção de biodiesel, produzido a partir da transesterificação de triglicerídeos de origem animal ou vegetal, tendo como características não ser tóxico, ser biodegradável e fonte renovável de energia. As lipases são enzimas que aceleram reações de hidrólise e síntese, podendo ser obtidas de microorganismos por meio de processos de fermentação em estado sólido, porém com alta demanda de recursos financeiros para sua produção. Hoje em dia, o que está em alta na indústria de tecnologia com enzimas é a utilização de resíduos agroindustriais e processos de imobilização com o intuito de diminuir os gastos em sua produção, um dos gargalos para seu uso mais amplo. Neste trabalho foi analisada a viabilidade do uso do bagaço de cana-de-açúcar misturado a farelos de soja ou trigo como meios de cultivo em fermentação semi-sólida, assim como a melhor concentração de umidade para o desenvolvimento de lipases pelo microorganismos estudados. Foi testada também a viabilidade de imobilização das lipases produzidas em suporte de celite

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Ultimamente várias áreas da ciência vêm se unindo a fim de compreender, elucidar, retardar e reverter o processo do envelhecimento da pele. Tal processo deve ser estudado, pois as mudanças no aspecto exterior podem revelar disfunções que ocorrem internamente, além de trazer conseqüências psíquicas sobre o comportamento da pessoa, tanto diante de si mesma como diante das outras. A utilização de matérias-primas naturais orgânicas em formulações farmacêuticas e cosméticas segue uma tendência de mercado, haja vista o grande impulso que o mercado orgânico tem ocasionado na economia. Dentre estas matérias-primas, destaca-se a utilização do cacau orgânico que, pelo fato de ser rico em compostos polifenólicos e taninos condensados, acredita-se apresentar potencial ação antioxidante. Associados a sistemas nanoestruturados inovadores, como os sistemas líquido-cristalinos constituídos por silicones formadores de filme, a ação antioxidante do cacau orgânico pode, dessa forma, ser potencializada. Este trabalho tem como objetivos desenvolver e caracterizar sistemas líquido-cristalinos acrescidos de extrato de semente de cacau orgânico, avaliar a estabilidade físico-química e a atividade antioxidante das formulações obtidas. Realizou-se a caracterização do pó de cacau por microscopia óptica. A partir do pó do cacau, obteve-se extratos hidroalcóolicos do pó, a partir do qual foram quantificados compostos fenólicos utilizando o reagente Folin-Ciocalteu e determinada a atividade antioxidante com base na ação seqüestrante do radical 1,1-difenil-2-picrilhidrazila (DPPH). Posteriormente, o extrato foi incorporado em um sistema constituído por acido oléico e polioxietileno 20 cetil éter, o qual foi caracterizado estruturalmente empregando análises de microscopia de luz polarizada, espalhamento de raios-X a baixo ângulo (SAXS) e comportamento reológico... (Resumo completo, clicar acesso eletrônico abaixo)

Relevância:

30.00% 30.00%

Publicador:

Resumo:

In this study, the drug indomethacin, a non-steroidal anti-inflammatory indoleacetic acid derivative and the complex of indomethacin and lanthanum (III) in solid form were synthesized and characterized by Thermogravimetry (TGA), Differential Thermal Analysis (DTA), Differential Scanning Calorimetry (DSC) and powder X-ray diffractometry (XRD), infrared vibrational spectroscopy by diffuse reflectance (FTIR) and complexometric titration with EDTA. With the TG curves it was possible to determine the stoichiometry of the complex as La(Ind)3·3.5H2O where Ind is the drug indomethacin. The result of thermal analyzes provided information on the thermal stability, enthalpy of dehydration and thermal behavior of the compounds. The infrared spectrum and with the aid of theoretical calculations suggests that the indomethacin is coordinated by the carboxylate group in the bidentate mode

Relevância:

30.00% 30.00%

Publicador:

Resumo:

This Final Paper had as it main goal to make a thermoanalytical study of lighter trivalent lanthanides (Lanthanum, Cerium, Praseodymium, Neodymium, Samarium and Europium) with the Ibuprofen ligand (nonsteroidal anti-inflammatory) that have a general formula LnL3.nH2O, on solid state, where Ln are the Lanthanides, L is the Ibuprofen ligand and n = number of water molecules of hydration that went from 1,0 to all the compounds. In order to characterize this compounds, it has been used the thermoanalytical techniques TG-DTA (thermogravimetry - Diferential Thermal Analysis) and DSC (Diferential Scanning Calorimetry), Fourier transformed infrared spectroscopy (FTIR) and complexometric titration with EDTA. Through the TG-DTA technique, it has been possible to set the thermal stability of the compounds, the number of thermal decomposition steps and temperatures that ocurred that also provided stoichiometry to the synthesized compounds. The DSC technique has shown the enthalpy of dehydration of the samarium and europium compounds, it was not possible to see it in the other compounds due to a endothermic peak on the DSC curve not being formed. In the case of neodymium, a thermal event ocurred, in which it could be a oxidative decarboxylation right after the dehydration. The infrared was utilised to study the carboxilate groups streches, and so, suggest a ligand metals compound coordination, that to this present paper has been a bidentade bridged coordenation. At last, the complexometric tritation was used to very the ammount of metal present in each compound, and so, verify if the proposed stoichiometry was according to the theory

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Vulnerability of patients with Down syndrome (DS) to oxidative stress and damage has been attributed to the overexpression of the superoxide dismutase gene, which is located in the triplicated critical region 21q22.2 of chromosome 21. The objective of this study was to investigate enzymatic and non-enzymatic antioxidant systems and levels of biomarkers of oxidative damage in saliva of patients with DS. Saliva samples were collected from 30 patients with DS and 30 controls, ranging in age from 14 to 24 years. The following parameters were analyzed: superoxide dismutase activity, concentration of malondialdehyde, carbonylated proteins, uric acid, vitamin C and total protein, peroxidase activity, and total antioxidant capacity. Patients with DS presented significantly higher superoxide dismutase activity and malondialdehyde levels than controls (p<0.05). On the other hand, no difference in carbonylated proteins or antioxidants (uric acid, vitamin C, peroxidase, and total antioxidant capacity) was observed between DS patients and controls (p>0.05). Patients with DS also presented higher salivary total protein content (p<0.05). In conclusion, despite similar antioxidant levels patients with DS are more vulnerable to oxidative stress in saliva as indicated by a significant increase in malondialdehyde concentration and superoxide dismutase activity

Relevância:

30.00% 30.00%

Publicador:

Resumo:

The uninterrupted rise in emission of greenhouse gases open way to the use of biofuels, due to politics that focus on fuel safe, clean and renewable. The use of microalgae for biodiesel production has been described as one of the most promising sources of biomass for biofuels. The aim of this study was to evaluate the extraction and lipid profile of the microalgae Dunaliella tertiolecta, Isochrysis galbana and Tetraselsim gracilis. The extractions were performed with solvents chloroform /methanol and petroleum ether. The lipid profile was analyzed by gas chromatography after transesterification.The petroleum ether showed more efficiency in the extraction, the best result obtained was in the microalgae D. tertiolecta with 19.52% of lipid. The lipid profile analysis indicated a biodiesel stable to oxidation and elevated viscosity

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Volleyball is a sport in which the laterality dominant limb shows superior strength and coordination because of its preferential use. Asymmetrical tendencies during the landing after the jump when striking or blocking actions are predominant for most part of game (ARRUDA; EDUARDO, 2008). Adaptations include imbalance of forces in static and dynamic motions at the knee joint, which increases risk for injury. Also, asymmetries in balance control during jumping and landing associate with a general postural instability that can be observed during static balance tasks. The purpose of this study was to investigate relationship between unequal lower limb strength (muscle imbalance) and postural stability levels in volleyball athletes and non-athletes. Nine female volleyball athletes and 10 active non-athletes participated in this study. Four encouters with participants were scheduled: three encounters in the bodybuilding gymnasium to collect anthropometric measures (weight, height for BMI, thigh circumference, which provided an initial diagnosis about asymmetry), and to perform the isometric strength test (i.e., leg press using a load cell and a force transducer to calculate uni an bilateral strength). The last encounter was in the laboratory where a balance test on a force platform was administered under five test conditions, with three repetitions each: baseline (natural standing position), one-leg standing, right side, with full vision (D_CV), and blindfolded (D_SV), one-leg standing, left side, with full vision (E_CV), and blindfolded (E_SV). The stability levels were evaluated using the path length parameters which was based on the total displacement of the center of pressure (DTCP). . Both groups shows asymmetric strength levels between legs, with better performance for the right leg. An ANOVA three way using the DTCP for the CV condition, legs (D x E), trials (3) with repeated measures for the first two factors and with a between (three)...

Relevância:

30.00% 30.00%

Publicador:

Resumo:

The present literature review aimed to describe biodisel’s physicochemical properties obtained from different raw materials. Were studied data concerning viscosity, density, cetane number, fl ash point, pour point and calorifi c power of biodiesel produced from soybean oil, coconut, rice bran, cotton, pequi, babassu, mamona, palm, castor, sunfl ower, corn, canola, jatropha and karanja. Considering the diversity of vegetal and animal sources that can be used on the biodiesel production, it is noteworthy the lack of data concerning physicochemical properties of unexplored raw materials. This work may contribute for the creation of database about physicochemical properties of oil and biodiesel from different sources which will allow design and scale-up, both the necessary equipment to the production line and reciprocating engines.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Liquid-liquid extraction is utilized for purification of biomolecules by Aqueous Biphasic Systems (ABS), since this process does not damage the biotechnological potential of these compounds. In this work, using the free software Scilab®, the fractionated liquid-liquid extraction was studied aiming a lipase (target enzyme) partition in a water + PEG + DEX system. Lisozime was considered as contaminant. As computer simulations has been extensively used when a first estimation of technical feasibility of process is desired, this work demonstred that the system is viable for recovery the 80 % till 90 % the target enzyme, but should be noted that the trial aimed only the fractionation of the enzyme target of a contaminant, not its concentration, which should be done by another process.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

In this study, use was made of tucumã cake, in natura (TCN) and thermally treated (TCT), as potential alternative adsorbents for the adsorption of cationic and anionic dyes. The effects of the parameters: contact time, adsorbent: adsorbate mass ratio, and initial concentration of dye were analyzed. The adsorption isotherms were established from optimized adsorption parameters. The best conditions for adsorption were: equilibrium time of 7 h, concentration of 25 mg L 1 and ratio of 1:200 for the methylene blue dye; and pH 6.5, concentration of 25 mg L 1 and ratio of 1:200 for the congo red dye. The adsorption process was best represented by the Dubinin–Radushkevich and Sips isotherms. The kinetics of adsorption of the dyes were best described by the pseudo-second-order kinetic and Elovich models. TCT showed the best maximum adsorption capacity (Qm) for the methylene blue dye (63.92 mg g 1 ).

Relevância:

30.00% 30.00%

Publicador:

Resumo:

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

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Biofuels and their blends with fossil fuel are important energy resources, which production and application have been largely increased internationally. This study focus on the development of a correlation between apparent activation energy (Ea) and NOx emission of the thermal decomposition of three pure fuels: farnasane (renewable diesel from sugar cane), biodiesel and fossil diesel and their blends. Apparent Activation energy was determined by using thermogravimetry and Model-Free Kinetics. NOx emission was obtained from the European Stationary Cycle (ESC) with OM 926LA CONAMA P7/Euro 5 engine. Results showed that there is a linear correlation between apparent activation energy and NOx emission with R2 of 0,9667 considering pure fuels and their blends which is given as: NOx = 2,2514Ea - 96,309. The average absolute error of this correlation is 2.96% with respect to the measured NOx value. The main advantage of this correlation is its capability to predict NOx emission when either a new pure fuel or a blend of fuels is proposed to use in enginees.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Pós-graduação em Agronomia (Ciência do Solo) - FCAV

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Pós-graduação em Agronomia (Ciência do Solo) - FCAV