161 resultados para extractor


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Sequential extraction is not totally effective to dissolve distinct forms of trace elements. The extractive solution, for example, can dissolve less of the target fraction and more than another not wished fraction. The goal of this work is to compare the extraction of native iron with three sequential extraction methods of the heavy metals, using three soils with different physical chemistry characteristics: a histosol, an oxisol, and a mollisol. The results obtained in this work demonstrate that a smaller relation soil/extractor results in a larger extraction in almost all phases. The use of many stages of the sequential extraction, with the purpose of more association of the metal with different components of the soil, can result, among other things, in modification of the substratum by the action of the reagents used, besides reducing the selectivity of the more specific extractors. Readsorption and redistribution of the heavy metals could have happened with larger intensity in the fraction where hidroxilamine was used with higher temperature. Sequential extraction of iron, without enrichment of soil samples, in the respective fractions in each method, it was important to better understand the behavior of the reagents considered specific to each form of the metal in soil.

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A new extraction method for sterols was tested in fruits of Ottonia martiana Miq., a shrub belonging to the family Piperaceae, popularly known as "anestésica" due to the use of its roots and aerial parts, in alcoholic preparations, in treatment of odontological problems. For this purpose, a portable extraction equipment was developed, to operate with liquified gases, which showed to be practical, fast and effective, besides being economical and ecological. In the chromatographic analysis of the extracts obtained in this equipment, it was demonstrated the presence of two sterols, isomers of b-sitosterol and stigmasterol.

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Background: As a result of the growing number of interventions that are now performed in the context of maternity care, health authorities have begun to examine the possible repercussions for service provision and for maternal and neonatal health. In Spain the Strategy Paper on Normal Childbirth was published in 2008, and since then the authorities in Catalonia have sought to implement its recommendations. This paper reviews the current provision of maternity care in Catalonia. Methods: This was a descriptive study. Hospitals were grouped according to their source of funding (public or private) and were stratified (across four strata) on the basis of the annual number of births recorded within their respective maternity service. Data regarding the distribution of obstetric professionals were taken from an official government survey of hospitals published in 2010. The data on obstetric interventions (caesarean, use of forceps, vacuum or non-specified instruments) performed in 2007, 2010 and 2012 were obtained by consulting discharge records of 44 public and 20 private hospitals, which together provide care in 98% of all births in Catalonia. Proportions and confidence intervals were calculated for each intervention performed in all full-term (3742 weeks) singleton births. Results: Analysis of staff profiles according to the stratification of hospitals showed that almost all the hospitals had more obstetricians than midwives among their maternity care staff. Public hospitals performed fewer caesareans [range between 19.20% (CI 18.84-19.55) and 28.14% (CI 27.73-28.54)] than did private hospitals [range between 32.21% (CI 31.78-32.63) and 39.43% (CI 38.98-39.87)]. The use of forceps has decreased in public hospitals. The use of a vacuum extractor has increased and is more common in private hospitals. Conclusions: Caesarean section is the most common obstetric intervention performed during full-term singleton births in Catalonia. The observed trend is stable in the group of public hospitals, but shows signs of a rise among private institutions. The number of caesareans performed in accredited public hospitals covers a limited range with a stable trend. Among public hospitals the highest rate of caesareans is found in non-accredited hospitals with a lower annual number of births.

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Background: As a result of the growing number of interventions that are now performed in the context of maternity care, health authorities have begun to examine the possible repercussions for service provision and for maternal and neonatal health. In Spain the Strategy Paper on Normal Childbirth was published in 2008, and since then the authorities in Catalonia have sought to implement its recommendations. This paper reviews the current provision of maternity care in Catalonia. Methods: This was a descriptive study. Hospitals were grouped according to their source of funding (public or private) and were stratified (across four strata) on the basis of the annual number of births recorded within their respective maternity service. Data regarding the distribution of obstetric professionals were taken from an official government survey of hospitals published in 2010. The data on obstetric interventions (caesarean, use of forceps, vacuum or non-specified instruments) performed in 2007, 2010 and 2012 were obtained by consulting discharge records of 44 public and 20 private hospitals, which together provide care in 98% of all births in Catalonia. Proportions and confidence intervals were calculated for each intervention performed in all full-term (3742 weeks) singleton births. Results: Analysis of staff profiles according to the stratification of hospitals showed that almost all the hospitals had more obstetricians than midwives among their maternity care staff. Public hospitals performed fewer caesareans [range between 19.20% (CI 18.84-19.55) and 28.14% (CI 27.73-28.54)] than did private hospitals [range between 32.21% (CI 31.78-32.63) and 39.43% (CI 38.98-39.87)]. The use of forceps has decreased in public hospitals. The use of a vacuum extractor has increased and is more common in private hospitals. Conclusions: Caesarean section is the most common obstetric intervention performed during full-term singleton births in Catalonia. The observed trend is stable in the group of public hospitals, but shows signs of a rise among private institutions. The number of caesareans performed in accredited public hospitals covers a limited range with a stable trend. Among public hospitals the highest rate of caesareans is found in non-accredited hospitals with a lower annual number of births.

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This work aimed at evaluating the contents of extractable Cd, Pb, Zn and Cu with a solution of DTPA (diethyleneaminopentacetic acid) and to relate them with the production of dry material and grain production of bean plants under two conditions of experimentally contaminated soil materials with Cd, Pb, Cu and Zn: (i) samples of distrofic red latosol and (ii) humic yellow-red latosol. A decrease in the yield of dry matter was observed for all treatments, if compared with the zero-dose control sample; the grain yield was affected for the soil samples treated with Cd and Cu but only slightly for those treated with Pb and Zn.

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The aim of the present work was to develop and optimize a method for determination of bioavailable phosphorus in samples of feces and fish feed using ultrasound extraction and subsequent quantification by visible spectrophotometry. Using as extractor solution HNO3 0.50 mol L-1, the great conditions of extraction established were: sample mass - 100 mg, samples granulometry - < 60 µm, sonification time - five cycles of 40 s and ultrasound potency - 136 W. The proposed method was applied in studies of digestibility of this nutrient in different feeds used in diets of juvenile of Nile tilapia.

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The objective of this study was to evaluate the use of the matrix solid-phase dispersion technique associated with purification at low temperature for the determination of pyrethroids in butter. Evaluated parameters included: sample/adsorbent ratio, type of adsorbent and extractor solvent. The optimized method was validated based on predetermined requirements. The detection limits of the pyrethroids cypermethrin and deltamethrin were 0.082 and 0.11 μg g-1, and quantification limit were 0.28 and 0.32 μg g-1, respectively, with extraction percentages near 90% and coefficients of variation less than of 10%..

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The aim of this study was to standardize the extractive solution of Syzygium cumini. The extractive solution was selected through a full factorial design, considering the extraction method (maceration-5-days, turbo extraction, percolation), extractor solvent (ethanol 50, 70, 96%) and plant material particle size 0.302 mm into a plant:solvent ratio (1:10), using the dried residue and antimicrobial activity determination as evaluation criteria. The tests were performed in triplicate. It appeared that the percolation is the best procedure extractive, and ethanol mixture: water (50:50) the best solvent. ANOVA analysis showed the importance of these parameters.

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Essential oils of ripe fruits from Schinus terebinthifolius (Anacardiaceae), obtained using a pilot extractor and a Clevenger apparatus were chemically characterized. Due the high amount of (-)- α-pinene in both oils, this monoterpene was tested against the protozoan parasite Trypanosoma cruzi, showing a moderate potential (IC50 63.56 µg/mL) when compared to benznidazole (IC50 43.14 µg/mL). Otherwise, (-)- α-pinene oxide did not showed anti-trypanosomal activity (IC50 > 400 µg/mL) while (-)-pinane showed an IC50 of 56.50 µg/mL. The obtained results indicated that the epoxydation of α-pinene results to the loss of the anti-parasitic activity while its hydrogenation product, contributed slightly to the increased activity.

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The objective of this study was to evaluate the relationships between the spectra in the Vis-NIR range and the soil P concentrations obtained from the PM and Prem extraction methods as well as the effects of these relationships on the construction of models predicting P concentration in Oxisols. Soil samples' spectra and their PM and Prem extraction solutions were determined for the Vis-NIR region between 400 and 2500 nm. Mineralogy and/or organic matter content act as primary attributes allowing correlation of these soil phosphorus fractions with the spectra, mainly at wavelengths between 450-550, 900-1100 nm, near 1400 nm and between 2200-2300 nm. However, the regression models generated were not suitable for quantitative phosphate analysis. Solubilization of organic matter and reactions during the PM extraction process hindered correlations between the spectra and these P soil fractions. For Prem,, the presence of Ca in the extractant and preferential adsorption by gibbsite and iron oxides, particularly goethite, obscured correlations with the spectra.

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Monet teollisuuden konenäkö- ja hahmontunnistusongelmat ovat hyvin samantapaisia, jolloin prototyyppisovelluksia suunniteltaessa voitaisiin hyödyntää pitkälti samoja komponentteja. Oliopohjaiset sovelluskehykset tarjoavat erinomaisen tavan nopeuttaa ohjelmistokehitystä uudelleenkäytettävyyttä parantamalla. Näin voidaan sekä mahdollistaa konenäkösovellusten laajempi käyttö että säästää kustannuksissa. Tässä työssä esitellään konenäkösovelluskehys, joka on perusarkkitehtuuriltaan liukuhihnamainen. Ylätason rakenne koostuu sensorista, datankäsittelyoperaatioista, piirreirrottimesta sekä luokittimesta. Itse sovelluskehyksen lisäksi on toteutettu joukko kuvankäsittely- ja hahmontunnistusoperaatioita. Sovelluskehys nopeuttaa selvästi ohjelmointityötä ja helpottaa uusien kuvankäsittelyoperaatioiden lisää mistä.

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This study aims at detailing bimodal pore distribution by means of water retention curve in an oxidic-gibbsitic Latosol and in a kaolinitic cambisol Latossol under conservation management system of coffee crop. Samples were collected at depths of 20; 40; 80; 120 and 160 cm on coffee trees rows and between rows under oxidic-gibbsitic Latosol (LVd) and kaolinitic cambisol Latossol (LVAd). Water retention curve was determined at matrix potentials (Ψm) -1; -2; -4; -6; -10 kPa obtained from the suction unit; the Ψm of -33; -100; -500; -1,500 kPa were obtained by the Richards extractor, and WP4-T psychrometer was used to determine Ψm -1,500 to -300,000 kPa. The water retention data were adjusted to the double van Genuchten model by nonlinear model procedures of the R 2.12.1 software. Was estimated the model parameter and inflection point slope. The system promoted changes in soil structure and water retention for the conditions evaluated, and both showed bimodal pores distribution, which were stronger in LVd. There was a strong influence of mineralogy gibbsitic in the water retention more negative than Ψm -1500 kPa, reflected in the values of the residual water content.

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The major type of non-cellulosic polysaccharides (hemicelluloses) in softwoods, the partly acetylated galactoglucomannans (GGMs), which comprise about 15% of spruce wood, have attracted growing interest because of their potential to become high-value products with applications in many areas. The main objective of this work was to explore the possibilities to extract galactoglucomannans in native, polymeric form in high yield from spruce wood with pressurised hot-water, and to obtain a deeper understanding of the process chemistry involved. Spruce (Picea abies) chips and ground wood particles were extracted using an accelerated solvent extractor (ASE) in the temperature range 160 – 180°C. Detailed chemical analyses were done on both the water extracts and the wood residues. As much as 80 – 90% of the GGMs in spruce wood, i.e. about 13% based on the original wood, could be extracted from ground spruce wood with pure water at 170 – 180°C with an extraction time of 60 min. GGMs comprised about 75% of the extracted carbohydrates and about 60% of the total dissolved solids. Other substances in the water extracts were xylans, arabinogalactans, pectins, lignin and acetic acid. The yields from chips were only about 60% of that from ground wood. Both the GGMs and other non-cellulosic polysaccharides were extensively hydrolysed at severe extraction conditions when pH dropped to the level of 3.5. Addition of sodium bicarbonate increased the yields of polymeric GGMs at low additions, 2.5 – 5 mM, where the end pH remained around 3.9. However, at higher addition levels the yields decreased, mainly because the acetyl groups in GGMs were split off, leading to a low solubility of GGMs. Extraction with buffered water in the pH range 3.8 – 4.4 gave similar yields as with plain water, but gave a higher yield of polymeric GGMs. Moreover, at these pH levels the hydrolysis of acetyl groups in GGMs was significantly inhibited. It was concluded that hot-water extraction of polymeric GGMs in good yields (up to 8% of wood) demands appropriate control of pH, in a narrow range about 4. These results were supported by a study of hydrolysis of GGM at constant pH in the range of 3.8 – 4.2 where a kinetic model for degradation of GGM was developed. The influence of wood particle size on hot-water extraction was studied with particles in the range of 0.1 – 2 mm. The smallest particles (< 0.1 mm) gave 20 – 40% higher total yield than the coarsest particles (1.25 – 2 mm). The difference was greatest at short extraction times. The results indicated that extraction of GGMs and other polysaccharides is limited mainly by the mass transfer in the fibre wall, and for coarse wood particles also in the wood matrix. Spruce sapwood, heartwood and thermomechnical pulp were also compared, but only small differences in yields and composition of extracts were found. Two methods for isolation and purification of polymeric GGMs, i.e. membrane filtration and precipitation in ethanol-water, were compared. Filtration through a series of membranes with different pore sizes separated GGMs of different molar masses, from polymers to oligomers. Polysaccharides with molar mass higher than 4 kDa were precipitated in ethanol-water. GGMs comprised about 80% of the precipitated polysaccharides. Other polysaccharides were mainly arabinoglucuronoxylans and pectins. The ethanol-precipitated GGMs were by 13C NMR spectroscopy verified to be very similar to GGMs extracted from spruce wood in low yield at a much lower temperature, 90°C. The obtained large body of experimental data could be utilised for further kinetic and economic calculations to optimise technical hot-water extractionof softwoods.

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Presentation at Open Repositories 2014, Helsinki, Finland, June 9-13, 2014

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The effective diffusivity of clove essential oil in subcritical liquid CO2 was estimated. The experimental apparatus employed was a fixed-bed extractor. The fixed bed was formed with grounded (mesh -32 + 65) and compacted clove buds which were considered a solid element. The effective diffusion coefficient was evaluated by fitting the experimental concentration profile to the unsteady state mass balance equation for unidirectional diffusion in a finite solid medium. The diffusion coefficient was related to the concentration of oil in the solid by an exponential function. The estimated values of the effective diffusion coefficient varied from 3.64 to 5.22x10-10 m2/s. The average relative errors were lower than 3.1%.