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Search Results: 1 - 10 of 468813 matches for " Adriano A. Mendes "
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Assessment of the Morphological, Biochemical, and Kinetic Properties for Candida rugosa Lipase Immobilized on Hydrous Niobium Oxide to Be Used in the Biodiesel Synthesis
Michele Miranda,Daniele Urioste,Livia T. Andrade Souza,Adriano A. Mendes,Heizir F. de Castro
Enzyme Research , 2011, DOI: 10.4061/2011/216435
Abstract: Lipase from Candida rugosa (CRL) was immobilized by covalent attachment on hydrous niobium oxide. The matrix could effectively be attached to the enzyme with high retention of activity and prevent its leakage. Following immobilization, CRL exhibited improved storage stability and performed better at higher incubation temperatures. In addition, the enzyme retained most of its catalytic efficiency after successive operational cycles. The immobilized derivative was also fully characterized with respect to its morphological properties: particle size, surface specific area, and pore size distribution. Structural integrity and conformational changes, such as surface cavities in the support, set by the lipase procedure, were observed by Scanning Electron Microscopy. Additionally, a comparative study between free and immobilized lipases was provided in terms of pH, temperature, and thermal stability. CRL derivative was evaluated for the synthesis of biodiesel employing babassu oil and short chain alcohols. The process was feasible only for oil and butanol reaction system. 1. Introduction Investigations of alternative renewable energy resources continue, with many studies focused on biodiesel fuels. One of the alternative renewable energy sources for diesel engines is vegetable oil. Studies have shown that pure vegetable oils are not a suitable direct replacement for diesel fuel, due to higher viscosity and molecular weight [1]. These properties cause incomplete combustion and engine deposits [2]. Therefore, several methods are used to reduce the viscosity of vegetable oil, such as transesterification reaction [3]. The transesterification reaction involves the reaction of alcohol with the oil, releasing glycerol as byproduct and monoalkyl esters (biodiesel), an excellent substitute for fossil fuels. In this reaction, alkali or acid are typically used as the catalysts resulting in high conversion levels in short reaction time [3, 4]. However, there are major drawbacks of such chemical process, as several problems during the steps of removal of catalyst from the product, recovery of glycerol, and the alkaline wastewater treatment, and interference of free fatty acid and water in the reaction and excessive consumption of energy [3, 4]. The use of heterogeneous catalysts, including immobilized lipases can overcome these problems which allow mild reaction conditions and no generation of chemical waste [3–7]. Lipases (E.C. 3.1.1.3) are ubiquitous enzymes with various biological activities, including triacylglycerols hydrolysis, esterification between fatty acid (FA)
Desempenho da matriz híbrida SiO2-quitosana na imobiliza??o da lipase microbiana de Candida rugosa
Sim?es, Aline S;Mori, Rodrigo Y;Faria, Raquel;Castro, Heizir F. de;Mendes, Adriano A;
Química Nova , 2011, DOI: 10.1590/S0100-40422011000100007
Abstract: lipase from candida rugosa was immobilized by covalent attachment on hybrid sio2-chitosan obtained by sol-gel technique. a comparative study between free and immobilized lipase was provided in terms of ph, temperature, kinetic parameters and thermal stability on the olive oil hydrolysis. the ph and temperature for maximum activity shifted from 7.0 and 45 oc for the free lipase to 7.5 and wide range of temperature (40-50 oc) after immobilization. kinetics parameters were found to obey michaelis-menten equation and km values indicated that immobilization process reduced the affinity of enzyme-substrate; however kd values revealed an increase of thermal stability of lipase.
Aplica??o de quitosana como suporte para a imobiliza??o de enzimas de interesse industrial
Mendes, Adriano A.;Oliveira, Pedro C. de;Castro, Heizir F. de;Giordano, Raquel de L. C.;
Química Nova , 2011, DOI: 10.1590/S0100-40422011000500019
Abstract: chitosan, poly[β-(1-4)-linked-2-amino-2-deoxy-d-glucose], is the n-deacetylated product of chitin which is a major component of arthropod and crustacean shells such as lobsters, crabs, shrimps, and cuttlefishes. in addition, chitosan has many significant biological and chemical properties such as biodegradability, biocompatibility and bioactivity as well as polycationic properties. thus, it has been widely used in many industrial and biomedical applications including wastewater treatment, chromatographic support, carriers for controlled drug delivery and enzyme immobilization. this review is an insight into the exploitation of utilization of chitosan based-supports in different geometrical configurations on the immobilization of enzymes by different protocols for further application in biotransformation reactions.
Simultaneous enzymatic hydrolysis and anaerobic biodegradation of lipid-rich wastewater from poultry industry
Gisanara Dors,Adriano A. Mendes,Ernandes B. Pereira,Heizir F. de Castro,Agenor Furigo Jr.
Applied Water Science , 2013, DOI: 10.1007/s13201-012-0075-9
Abstract: Simultaneous enzymatic hydrolysis and anaerobic biodegradation of lipid-rich wastewater from poultry industry with porcine pancreatic lipase at different concentrations (from 1.0 to 3.0 g L 1) were performed. The efficiency of the enzymatic pretreatment was measured by the Chemical Oxygen Demand (COD) removal and formation of methane. All samples pretreated with lipase showed a positive effect on the COD removal and formation of methane. After 30 days of anaerobic biodegradation the methane production varied from 569 ± 95 to 1,101 ± 10 mL for crude wastewater and pretreated at 3.0 g L 1 enzyme, respectively. COD removal of wastewater supplemented at different enzyme concentrations was found to be threefold higher than crude wastewater. The use of lipases seems to be a promising alternative for treating lipid-rich wastewaters such as those from the poultry industry.
Immobilization of a Commercial Lipase from Penicillium camembertii (Lipase G) by Different Strategies
Adriano A. Mendes,Larissa Freitas,Ana Karine F. de Carvalho,Pedro C. de Oliveira,Heizir F. de Castro
Enzyme Research , 2011, DOI: 10.4061/2011/967239
Abstract: The objective of this work was to select the most suitable procedure to immobilize lipase from Penicillium camembertii (Lipase G). Different techniques and supports were evaluated, including physical adsorption on hydrophobic supports octyl-agarose, poly(hydroxybutyrate) and Amberlite resin XAD-4; ionic adsorption on the anionic exchange resin MANAE-agarose and covalent attachment on glyoxyl-agarose, MANAE-agarose cross-linked with glutaraldehyde, MANAE-agarose-glutaraldehyde, and epoxy-silica-polyvinyl alcohol composite. Among the tested protocols, the highest hydrolytic activity (128.2 ± 8.10?IU·g?1 of support) was achieved when the lipase was immobilized on epoxy-SiO2-PVA using hexane as coupling medium. Lipase immobilized by ionic adsorption on MANAE-agarose also gave satisfactory result, attaining 55.6 ± 2.60?IU·g?1 of support. In this procedure, the maximum loading of immobilized enzyme was 9.3?mg·g?1 of gel, and the highest activity (68.8 ± 2.70?IU·g?1 of support) was obtained when 20?mg of protein·g?1 was offered. Immobilization carried out in aqueous medium by physical adsorption on hydrophobic supports and covalent attachment on MANAE-agarose-glutaraldehyde and glyoxyl-agarose was shown to be unfeasible for Lipase G. Thermal stability tests revealed that the immobilized derivative on epoxy-SiO2-PVA composite using hexane as coupling medium had a slight higher thermal stability than the free lipase. 1. Introduction Lipases (triacylglycerol acyl hydrolases EC 3.1.1.3) are hydrolases that act on carboxylic ester bonds. The natural physiologic role of lipases is the hydrolysis of triglycerides into fatty acids and glycerol, but they can also catalyze esterifications and interesterifications in nonaqueous media [1–5]. A peculiarity mechanism action of lipases is the interfacial activation. Most lipases have a α-helical oligopeptide structure covering their active site (lid or flap) and making them inaccessible to substrates. In the absence of a hydrophobic interface, the active site is secluded from the reaction medium, and the enzyme is in the so-called “closed conformation.” However, in the presence of a hydrophobic interface (a drop of oil), the lipase changes its conformation and exposes the catalytic site to the hydrophobic phase, yielding the “open conformation” [6–9]. The limitations of the industrial use of lipases have been mainly due to their high cost, which may be overcome by immobilization techniques on solid supports. Immobilization facilitates the separation of products and provides more flexibility with enzyme/substrate contact by
Modifica??o de óleos e gorduras por biotransforma??o
Castro, Heizir F. de;Mendes, Adriano A.;Santos, Júlio C. dos;Aguiar, Cláudio L. de;
Química Nova , 2004, DOI: 10.1590/S0100-40422004000100025
Abstract: the oleochemical industry has a permanent interested in controlling the physical, functional and organoleptical properties of their products and in producing useful derivatives from their raw materials. the potential of biotechnology for developing novel or well-known products at more competitive costs meets the need of this industrial segment in expanding their goals. in this work some technical aspects, problems and perspectives related to the production of oil and fat derivatives using biotransformation techniques are discussed. particular emphasis is given to the description of biotransformation processes using lipase as catalyst, in view of the great versatility of this enzyme class to mediate typical reactions in this technological sector.
Modifica o de óleos e gorduras por biotransforma o
Castro Heizir F. de,Mendes Adriano A.,Santos Júlio C. dos,Aguiar Cláudio L. de
Química Nova , 2004,
Abstract: The oleochemical industry has a permanent interested in controlling the physical, functional and organoleptical properties of their products and in producing useful derivatives from their raw materials. The potential of biotechnology for developing novel or well-known products at more competitive costs meets the need of this industrial segment in expanding their goals. In this work some technical aspects, problems and perspectives related to the production of oil and fat derivatives using biotransformation techniques are discussed. Particular emphasis is given to the description of biotransformation processes using lipase as catalyst, in view of the great versatility of this enzyme class to mediate typical reactions in this technological sector.
Application of the Concept of Terminal Value in the Analysis of Projects Based on Renewable Energy  [PDF]
Adriano Beluco, Alexandre Beluco, Carlos André Bulh?es Mendes
Journal of Power and Energy Engineering (JPEE) , 2018, DOI: 10.4236/jpee.2018.66002
Abstract: Projects for energy supply based on the exploitation of renewable energy have a very predictable cash flow. The initial costs are usually high, with the acquisition of technologically evolving equipment. However, maintenance costs are relatively low and easily predictable. Likewise, operating costs are often very low as there is no need to buy inputs. Power storage devices are often short-lived and contribute to a relative cost increase. At the same time, these projects are often not approved because they are directly compared to projects based on non-renewable resources, with cash flows that may not be so easily predictable and with much lower start-up costs. Fossil fuels have hardly predictable costs, established by non-technical criteria and related to geopolitical issues. In addition, their operating costs are usually very high, precisely because of the need to purchase fossil fuels. This paper proposes the calculation of terminal value in cash flows of power generation projects and its application for feasibility analysis of projects based on renewable resources. The proposed method suggests the calculation of terminal value as the moving average calculated for five-year intervals with constant growth rate of 5%. This method also encourages the inclusion in the cash flow of annual values that add up to the end of the analysis period the sufficient value to renew the system components at the end of the usual analysis period of 20 - 25 years. The application of the proposed method to a diesel wind system simulated with the well-known Homer software indicates the modification of the results of the Homer with the preference for systems with greater wind penetration instead of the systems with greater consumption of fossil fuels.
Tratamento com stent em tronco de artéria coronária esquerda por compress?o do tronco da artéria pulmonar em paciente com hipertens?o pulmonar esquistossomótica
Mendes, Adriano Assis;Japyassu, Flávio A. A.;Roberto, Flávio;Lamprea, Diana;Albuquerque, Eugênio;Roncal, Carlos G. P.;Cartaxo, Henrique Q.;Farias, Suela D.;
Revista Brasileira de Cardiologia Invasiva , 2010, DOI: 10.1590/S2179-83972010000100017
Abstract: pulmonary hypertension is frequently associated to chest pain with anginous characteristics and its etiology is uncertain. extrinsic compression of the left main coronary artery by the pulmonary artery is a treatable cause and should be taken into consideration. we present the case of a patient with pulmonary hypertension of schistosomotic etiology presenting angina due to compression of the left main coronary artery, who was treated with an intracoronary stent. signs and symptoms of ischemia were completely resolved and a late follow-up intravascular ultrasound confirmed the vessel patency.
Distúrbios metabólicos e adiposidade em uma popula??o rural
Silva, Daniele A.;Felisbino-Mendes, Mariana S.;Pimenta, Adriano M.;Gazzinelli, Andrea;Kac, Gilberto;Velásquez-Meléndez, Gustavo;
Arquivos Brasileiros de Endocrinologia & Metabologia , 2008, DOI: 10.1590/S0004-27302008000300009
Abstract: the aim of this cross-sectional study was to verify the prevalence of overweight and central adiposity (ca) in a sample of 287 adult subjects that lived in a rural community of minas gerais state. means lipids, lipoproteins, glucose and blood pressure levels were compared according adiposity categories using one-way anova and tukey tests. prevalence of overweight was 24.8% (37.4% for female; 11.5% for male). ca was verified in 28.1% of the individuals (50.3% for female; 4.3% for male). the associations between ca and overweight with the metabolic disorders: arterial hypertension (ah), dyslipidemia and hyperglycemia were estimated. subjects with ca presented higher mean values of blood pressure, total cholesterol, ldl, triglycerides, fasting glucose, and lower mean values of hdl. ca was associated with ah, dyslipidemia and hyperglycemia. associations between overweight and ah, dyslipidemia and hyperglycemia were also verified. these results confirm the potential effect of body composition shifting, especially at the abdominal level, on lipids, glucose metabolism and on blood pressure levels in rural populations.
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