10 resultados para SUPERCRITICAL FLUID EXTRACTION WITH CO2

em Repositório da Produção Científica e Intelectual da Unicamp


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Extracts from malagueta pepper (Capsicum frutescens L.) were obtained using supercritical fluid extraction (SFE) assisted by ultrasound, with carbon dioxide as solvent at 15MPa and 40°C. The SFE global yield increased up to 77% when ultrasound waves were applied, and the best condition of ultrasound-assisted extraction was ultrasound power of 360W applied during 60min. Four capsaicinoids were identified in the extracts and quantified by high performance liquid chromatography. The use of ultrasonic waves did not influence significantly the capsaicinoid profiles and the phenolic content of the extracts. However, ultrasound has enhanced the SFE rate. A model based on the broken and intact cell concept was adequate to represent the extraction kinetics and estimate the mass transfer coefficients, which were increased with ultrasound. Images obtained by field emission scanning electron microscopy showed that the action of ultrasonic waves did not cause cracks on the cell wall surface. On the other hand, ultrasound promoted disturbances in the vegetable matrix, leading to the release of extractable material on the solid surface. The effects of ultrasound were more significant on SFE from larger solid particles.

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The aim of this study was to compare the performance of the following techniques on the isolation of volatiles of importance for the aroma/flavor of fresh cashew apple juice: dynamic headspace analysis using PorapakQ(®) as trap, solvent extraction with and without further concentration of the isolate, and solid-phase microextraction (fiber DVB/CAR/PDMS). A total of 181 compounds were identified, from which 44 were esters, 20 terpenes, 19 alcohols, 17 hydrocarbons, 15 ketones, 14 aldehydes, among others. Sensory evaluation of the gas chromatography effluents revealed esters (n = 24) and terpenes (n = 10) as the most important aroma compounds. The four techniques were efficient in isolating esters, a chemical class of high impact in the cashew aroma/flavor. However, the dynamic headspace methodology produced an isolate in which the analytes were in greater concentration, which facilitates their identification (gas chromatography-mass spectrometry) and sensory evaluation in the chromatographic effluents. Solvent extraction (dichloromethane) without further concentration of the isolate was the most efficient methodology for the isolation of terpenes. Because these two techniques also isolated in greater concentration the volatiles from other chemical classes important to the cashew aroma, such as aldehydes and alcohols, they were considered the most advantageous for the study of cashew aroma/flavor.

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Nanorap is a new nanotechnological formulation for topical anesthesia composed of lidocaine (2.5%) and prilocaine (2.5%). The present study evaluated the pharmacokinetics (PK) of Nanorap. For the determination of lidocaine and prilocaine in human plasma a new method using high-performance liquid-chromatography coupled to tandem mass spectrometry was developed. Nanorap pharmacodynamic (PD) and its physical proprieties were also evaluated. Nanorap was administered by topical application of 2g to healthy volunteers and blood samples were collected for the PK analysis. The drugs were extracted from plasma by liquid-liquid extraction with ether/hexane (80/20, v/v). The chromatography separation was performed on a Genesis C18 analytical column 4 µm (100 x 2.1 mm i.d.) with a mobile phase of methanol/acetonitrile/water (40/30/30, for lidocaine, and 50/30/20, for prilocaine, v/v/v) + 2 mM of ammonium acetate and ropivacaine as internal standard. The drugs were quantified using a mass spectrometer with an electrospray source in the ESI positive mode (ES+) configured for multiple reaction monitoring. The PD of Nanorap was evaluated with the use of a visual analogue scale. Nanorap was characterized by cryofracture. The chromatography run time was 5.5 min for lidocaine and 3.3 min for prilocaine and the lower limit of quantification was 0.05 ng/mL for both drugs. Mean Cmax was 6.62 and 1.72 ng/mL for lidocaine and prilocaine, respectively. Median Tmax was 6.5 hours for both drugs. Nanocapsules had a mean size of 88nm and mean drug association of 92.5% and 89% for lidocaine and prilocaine, respectively. The PD study showed that Nanorap has a sufficient analgesic effect (>30% reduction in pain) after 10 minutes of application. A new simple, selective and sensitive method for determination of lidocaine and prilocaine in human plasma was developed. Nanorap generated safe plasma levels of the drugs and satisfactory analgesic effect.

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It was proposed to evaluate the hydroponic lettuce production, variety Vera, on inclined benches with channels of 100 mm, and Nutrient Film Technique, as answer to carbon dioxide application and evaporative cooling. There were five cycles of cultivation from March, 20th to April, 17th (C1); from May, 25th to June, 29th (C2); from July, 13th to August, 20th (C3); from August, 27th to October, 10th (C4); from December, 12th to January, 10th (C5). In three greenhouses were tested the following systems: (A1) without evaporative cooling air CO2 aerial injection, (A2) with CO2 aerial injection and without evaporative cooling and (A3) with CO2 aerial injection and pad-fan evaporative cooling system. The fresh and dry mass of leaves in grams, number of leaves and leaf area in square millimeter were evaluated. The completely randomized statistical analysis was used. The cycle C1 were used 48 replications, for cycles C2, C3 and C5 were used 64 replications and C5 were used 24 replications. The results showed that greenhouse with evaporative cooling system and CO2 allow better development and greater lettuce yield. It was possible to conclude that the aerial injection of CO2, in the absence of evaporative cooling system, did not lead increasing the lettuce productivity to most cycles. Bigger lettuce leaf areas were found in periods with higher temperatures.

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Evolving interfaces were initially focused on solutions to scientific problems in Fluid Dynamics. With the advent of the more robust modeling provided by Level Set method, their original boundaries of applicability were extended. Specifically to the Geometric Modeling area, works published until then, relating Level Set to tridimensional surface reconstruction, centered themselves on reconstruction from a data cloud dispersed in space; the approach based on parallel planar slices transversal to the object to be reconstructed is still incipient. Based on this fact, the present work proposes to analyse the feasibility of Level Set to tridimensional reconstruction, offering a methodology that simultaneously integrates the proved efficient ideas already published about such approximation and the proposals to process the inherent limitations of the method not satisfactorily treated yet, in particular the excessive smoothing of fine characteristics of contours evolving under Level Set. In relation to this, the application of the variant Particle Level Set is suggested as a solution, for its intrinsic proved capability to preserve mass of dynamic fronts. At the end, synthetic and real data sets are used to evaluate the presented tridimensional surface reconstruction methodology qualitatively.

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Different brands and batches of brazilian regular and instant coffee were purchased in supermarkets of Campinas? city and analysed for caffeine content. The method used involved extraction with boiling water, clarification with saturated basic acetate and determination by high performance liquid cromatography. Analysis was carried out using a Model 6000 A solvent delivery system (Waters associates), and a Model 7125 sample injector system (Reodyne, Inc.) with a 5µl sample loop. The system was also equipped with a Waters Model M440 absorbance detector set at 254 nm. A Merck ODS 5µm column (15 cm x 4.6 mm i.d.) was used to separate the caffeine. The mobile phase was methanol:water (25:75, v/v). The caffeine content varied for different brands and types of coffee and according to the beverage preparation technique. Values in the range of 0.43 to 0.85 mg/ml and 0.61 to 0.82 mg/ml were determined in regular and instant coffee, respectively.

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Evolving interfaces were initially focused on solutions to scientific problems in Fluid Dynamics. With the advent of the more robust modeling provided by Level Set method, their original boundaries of applicability were extended. Specifically to the Geometric Modeling area, works published until then, relating Level Set to tridimensional surface reconstruction, centered themselves on reconstruction from a data cloud dispersed in space; the approach based on parallel planar slices transversal to the object to be reconstructed is still incipient. Based on this fact, the present work proposes to analyse the feasibility of Level Set to tridimensional reconstruction, offering a methodology that simultaneously integrates the proved efficient ideas already published about such approximation and the proposals to process the inherent limitations of the method not satisfactorily treated yet, in particular the excessive smoothing of fine characteristics of contours evolving under Level Set. In relation to this, the application of the variant Particle Level Set is suggested as a solution, for its intrinsic proved capability to preserve mass of dynamic fronts. At the end, synthetic and real data sets are used to evaluate the presented tridimensional surface reconstruction methodology qualitatively.

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Purpose: To evaluate the onset time and quality of peribulbar anesthesia with 1% ropivacaine associated or not with hyaluronidase 100 tru/ml for cataract extraction. Methods: Prospective, randomized, double-blind and controlled study including fifty-seven patients, scheduled to undergo peribulbar anesthesia for cataract extraction, allocated to two groups. Group C: 1% ropivacaine with addition of 100 tru/ml hyaluronidase, and Group S 1% ropivacaine, without hyaluronidase. The onset time for globe akinesia was studied at intervals of 2 minutes, using Nicoll's score. We evaluated pain by analogic score during the surgery and the necessity of complementing the anaesthesia. The peribulbar block was considered satisfactory when the Nicoll's score was less than 4. Results: The mean time of onset of block in group C was 4.07 minutes (± 3.24), and in group S 5.03 (± 3.28). There was no statistically significant difference between the groups. Both were similar regarding pain score, no pain was observed in 57.14% of group C, and in 68.97% of group S. The supplementary anesthetic was necessary in 2 cases of group C and in 3 cases of group S. Two cases of bradycardia (heart rate < 50 bpm) were observed during the surgery, and in one case administration of atropine IV was necessary. Conclusion: 1% ropivacaine provided a good quality of anesthesia for cataract extraction, with a faster onset of action in the group with hyaluronidase 100 iu/ml, although without significant difference.

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The caffeine solubility in supercritical CO2 was studied by assessing the effects of pressure and temperature on the extraction of green coffee oil (GCO). The Peng-Robinson¹ equation of state was used to correlate the solubility of caffeine with a thermodynamic model and two mixing rules were evaluated: the classical mixing rule of van der Waals with two adjustable parameters (PR-VDW) and a density dependent one, proposed by Mohamed and Holder² with two (PR-MH, two parameters adjusted to the attractive term) and three (PR-MH3 two parameters adjusted to the attractive and one to the repulsive term) adjustable parameters. The best results were obtained with the mixing rule of Mohamed and Holder² with three parameters.

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Caryocar brasiliense Camb (Pequi) is a typical Brazilian Cerrado fruit tree. Its fruit is used as a vitamin source for culinary purposes and as a source of oil for the manufacture of cosmetics. C. brasiliense supercritical CO2 extracts exhibit antimicrobial activity against the bacteria Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus and also possess antioxidant activity. This study was designed to evaluate the in vitro cytotoxicity and phototoxicity of the supercritical CO2 extract obtained from the leaves of this species. In vitro cytotoxicity and phototoxicity of C. brasiliense supercritical CO2 extracts were assessed using a tetrazolium-based colorimetric assay (XTT) and Neutral Red methods. We found that the C. brasiliense (Pequi) extract obtained by supercritical CO2 extraction did not present cytotoxic and phototoxic hazards. This finding suggests that the extract may be useful for the development of cosmetic and/or pharmaceutical products.