Effects of limonene, n-decane and n-decanol on growth and membrane fatty acid composition of the microalga Botryococcus braunii.

Botryococcus braunii is a promising microalga for the production of biofuels and other chemicals because of its high content of internal lipids and external hydrocarbons. However, due to the very thick cell wall of B. braunii, traditional chemical/physical downstream processing very often is not as effective as expected and requires high amounts of energy. In this cases, the application of two-phase aqueous-organic solvent systems could be an alternative to cultivate microalgae allowing for a simultaneous extraction of the valuable compounds without significant negative effects on cell growth. Two-phase systems have been applied before, however, there are no studies so far on the mechanisms used by microalgae to survive in contact with solvents present as a second-phase. In this study, the effects of the solvents limonene, n-decane and n-decanol on growth of the microalga B. braunii as well as the adaptive cell response in terms of their phospholipid fatty acid contents were analized. A concentration-dependent negative effect of all three solvents on cell growth was observed. Effects were accompanied by changes of the membrane fatty acid composition of the alga as manifested by a decrease of the unsaturation . In addition, an association was found between the solvent hydrophobicity (given as log octanol-water partition coefficient ([Formula: see text]) values) and their toxic effects, whereby n-decanol and n-decane emerged as the most and least toxic solvent respectively. Among the tested solvents, the latter promises to be the most suitable for a two-phase extraction system.

Lipase-catalyzed process in an anhydrous medium with enzyme reutilization to produce biodiesel with low acid value.

One major problem in the lipase-catalyzed production of biodiesel or fatty acid methyl esters (FAME) is the high acidity of the product, mainly caused by water presence, which produces parallel hydrolysis and esterification reactions instead of transesterification to FAME. Therefore, the use of reaction medium in absence of water (anhydrous medium) was investigated in a lipase-catalyzed process to improve FAME yield and final product quality. FAME production catalyzed by Novozym 435 was carried out using waste frying oil (WFO) as raw material, methanol as acyl acceptor, and 3Å molecular sieves to extract the water. The anhydrous conditions allowed the esterification of free fatty acids (FFA) from feedstock at the initial reaction time. However, after the initial esterification process, water absence avoided the consecutives reactions of hydrolysis and esterification, producing FAME mainly by transesterification. Using this anhydrous medium, a decreasing in both the acid value and the diglycerides content in the product were observed, simultaneously improving FAME yield. Enzyme reuse in the anhydrous medium was also studied. The use of the moderate polar solvent tert-butanol as a co-solvent led to a stable catalysis using Novozym 435 even after 17 successive cycles of FAME production under anhydrous conditions. These results indicate that a lipase-catalyzed process in an anhydrous medium coupled with enzyme reuse would be suitable for biodiesel production, promoting the use of oils of different origin as raw materials.

Biotechnological processes for biodiesel production using alternative oils.

As biodiesel (fatty acid methyl ester (FAME)) is mainly produced from edible vegetable oils, crop soils are used for its production, increasing deforestation and producing a fuel more expensive than diesel. The use of waste lipids such as waste frying oils, waste fats, and soapstock has been proposed as low-cost alternative feedstocks. Non-edible oils such as jatropha, pongamia, and rubber seed oil are also economically attractive. In addition, microalgae, bacteria, yeast, and fungi with 20% or higher lipid content are oleaginous microorganisms known as single cell oil and have been proposed as feedstocks for FAME production. Alternative feedstocks are characterized by their elevated acid value due to the high level of free fatty acid (FFA) content, causing undesirable saponification reactions when an alkaline catalyst is used in the transesterification reaction. The production of soap consumes the conventional catalyst, diminishing FAME production yield and simultaneously preventing the effective separation of the produced FAME from the glycerin phase. These problems could be solved using biological catalysts, such as lipases or whole-cell catalysts, avoiding soap production as the FFAs are esterified to FAME. In addition, by-product glycerol can be easily recovered, and the purification of FAME is simplified using biological catalysts.

Improving fatty acid methyl ester production yield in a lipase-catalyzed process using waste frying oils as feedstock.

The application of waste frying oil (WFO) mixed with rapeseed oil as a feedstock for the effective production of fatty acid methyl esters (FAME) in a lipase-catalyzed process was investigated. The response surface methodology (RSM) was used to optimize the interaction of four variables: the percentage of WFO in the mixed feedstock, the methanol-to-oil ratio, the dosage of Novozym 435 as a catalyst and the temperature. Furthermore, the addition of methanol to the reaction mixture in a second step after 8 h was shown to effectively diminish enzyme inhibition. Using this technique, the model predicted the optimal conditions that would reach 100% FAME, including a methanol-to-oil molar ratio of 3.8:1, 100% (wt) WFO, 15% (wt) Novozym 435 and incubation at 44.5 degrees C for 12 h with agitation at 200 rpm, and verification experiments confirmed the validity of the model. According to the model, the addition of WFO increased FAME production yield, which is largely due to its higher contents of monoacylglycerols, diacylglycerols and free fatty acids (in comparison to rapeseed oil), which are more available substrates for the enzymatic catalysis. Therefore, the replacement of rapeseed oil with WFO in Novozym 435-catalyzed processes could diminish biodiesel production costs since it is a less expensive feedstock that increases the production yield and could be a potential alternative for FAME production on an industrial scale.

Teste de esforço: alteraçöes do segmento ST retritas à fase de recuperaçäo / Exercise testing: abnormal ST segments restrict to recovery phase

Objetivo. Determinar a incidência de doença coronária aterosclerótica (DCA) e/ou isquemia miocárdica em pacientes (pt) com alteraçoes do segmento ST restrita à fase de recuperaçao (ASTRR) do teste ergométrico. Casuística e Método. Estudo retrospectivo em 19 pacientes nao consecutivos com ASTRR, através da cinecoronariografia e/ou cintigrafia de esforço planar. Amostra de 18 homens, uma mulher, com idade de 58 + 9 anos, 18 sintomáticos. Resultados. ASTRR corresponderam a segmentos ST infra-desnivelados de 1 a 4 mm da linha de base, com inversao da onda T durante a recuperaçao precoce (2pt), tardia (14 pt). Foi documentada DCA em 14 pt (nove submetidos à cirurgia de revascularizaçao); miocardiopatia hipertensiva com coronárias normais em 3 pt e prolapso de válvula mitral em 1 pt. Em 13 casos a cinecoronariografia eóu cintilografia de esforço foram realizados dentro de seis meses do Teste Ergométrico, sendo a presença de DCA e ou isquemia miocárdica detectada em 8 pt. Em 3 pt, testes ergométricos sucessivos mostraram ASTRR reprodutíveis em dois casos. Conlusao. Os autores relatam a elevada prevalência de DCA e ou hipoperfusao transitória na cintigrafia de esforço em homens sintomáticos de meia idade com ASTRR no teste de esforço.

[Percutaneous retrieval of intravascular foreign bodies]. / Retirada percutânea de corpos estranhos intravasculares.

PURPOSE: To report our experience on percutaneous vascular foreign body retrieval and to analyse current techniques employed. METHODS: From 1985 to 1991, 15 (0.18%) of 7,963 procedures performed in the Cardiac Catheterization Laboratory-Hospital São Paulo were intravascular foreign body retrieval: 9 (60%) intracath, 4 (26.8%) diagnostic catheters, one Swan Ganz catheter entrapped at superior cava vein and one fragment of angioplasty guide-wire in the circumflex branch of the left coronary artery. The snare technique was used in 11 cases, a endomyocardial bioptome device in 1 case and modified snare technique for the intracoronary wire fragment retrieval was used in 1 case. In two cases of embolized fragment in peripheral arteries, no attempt was done for retrieval. RESULTS: All (100%) of the 13 attempted procedures were successful. The two foreign bodies not removed had an uneventful follow-up. CONCLUSION: The snare technique for percutaneous retrieval of intravascular foreign bodies is safe and has excellent results. The management peripheral fragments is not well defined yet.