953 resultados para extraction method


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Intravascular ultrasound (IVUS) image segmentation can provide more detailed vessel and plaque information, resulting in better diagnostics, evaluation and therapy planning. A novel automatic segmentation proposal is described herein; the method relies on a binary morphological object reconstruction to segment the coronary wall in IVUS images. First, a preprocessing followed by a feature extraction block are performed, allowing for the desired information to be extracted. Afterward, binary versions of the desired objects are reconstructed, and their contours are extracted to segment the image. The effectiveness is demonstrated by segmenting 1300 images, in which the outcomes had a strong correlation to their corresponding gold standard. Moreover, the results were also corroborated statistically by having as high as 92.72% and 91.9% of true positive area fraction for the lumen and media adventitia border, respectively. In addition, this approach can be adapted easily and applied to other related modalities, such as intravascular optical coherence tomography and intravascular magnetic resonance imaging. (E-mail: matheuscardosomg@hotmail.com) (C) 2011 World Federation for Ultrasound in Medicine & Biology.

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This paper considers two aspects of the nonlinear H(infinity) control problem: the use of weighting functions for performance and robustness improvement, as in the linear case, and the development of a successive Galerkin approximation method for the solution of the Hamilton-Jacobi-Isaacs equation that arises in the output-feedback case. Design of nonlinear H(infinity) controllers obtained by the well-established Taylor approximation and by the proposed Galerkin approximation method applied to a magnetic levitation system are presented for comparison purposes.

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The crosstalk phenomenon consists in recording the volume-conducted electromyographic activity of muscles other than that under study. This interference may impair the correct interpretation of the results in a variety of experiments. A new protocol is presented here for crosstalk assessment between two muscles based on changes in their electrical activity following a reflex discharge in one of the muscles in response to nerve stimulation. A reflex compound muscle action potential (H-reflex) was used to induce a silent period in the muscle that causes the crosstalk, called here the remote muscle. The rationale is that if the activity recorded in the target muscle is influenced by a distant source (the remote muscle) a silent period observed in the electromyogram (EMG) of the remote muscle would coincide with a decrease in the EMG activity of the target muscle. The new crosstalk index is evaluated based on the root mean square (RMS) values of the EMGs obtained in two distinct periods (background EMG and silent period) of both the remote and the target muscles. In the present work the application focused on the estimation of the degree of crosstalk from the soleus muscle to the tibialis anterior muscle during quiet stance. However, the technique may be extended to other pairs of muscles provided a silent period may be evoked in one of them. (C) 2009 IPEM. Published by Elsevier Ltd. All rights reserved.

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The purpose of this paper is to study metal separation from a sample composed of a mixture of the main types of spent household batteries, using a hydrometallurgical route, comparing selective precipitation and liquid-liquid extraction separation techniques. The preparation of the solution consisted of: grinding the waste of mixed batteries, reduction and volatile metals elimination using electric furnace and acid leaching. From this solution two different routes were studied: selective precipitation with sodium hydroxide and liquid-liquid extraction using Cyanex 272 [bis(2,4,4-trimethylpentyl) phosphoric acid] as extracting agent. The best results were obtained from liquid-liquid extraction in which Zn had a 99% extraction rate at pH 2.5. More than 95% Fe was extracted at pH 7.0, the same pH at which more than 90% Ce was extracted. About 88% Mn, Cr and Co was extracted at this pH. At pH 3.0, more than 85% Ni was extracted, and at pH 3.5 more than 80% of Cd and La was extracted. (C) 2010 Elsevier Ltd. All rights reserved.

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This work describes the preparation and characterization of biogenic modified silica from rice hull ash and its use as a sorbent of cadmium ions. Thus, an agro-industrial residue has been used to produce a new adsorbent product which is able to remove toxic elements. Mesoporous biogenic silica was obtained by alkaline extraction of sodium silicate by hydrolysis with the sol-gel process, and it was modified with salen using 1,2-dichloroethane as a spacer. The surface area of the silica was measured by nitrogen adsorption/desorption analysis. Surface modification was measured by Fourier transform infrared spectroscopy. The degree of functionalization was obtained by elemental analysis. This work showed that biogenic modified silica can be produced in aqueous media from rice hull ash using a simple method, providing an alternative method for adsorbent preparation. Thermogravimetric analysis showed that the salen-modified silica is stable up to 209 C. The modified silica displays appropriate structural characteristics for an adsorbent. The cylindrical pores, open at both ends, allow free diffusion of cadmium ions to the adsorption sites on the silica surface. The surface modification increases cadmium adsorption on the silica surface 100-fold. The salen-modified silica showed specific adsorption for Cd2+ of 44.52 mg/g SiO2 at cadmium concentration of 100 mg/l.

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A method based on a specific power-law relationship between the hydraulic head and the Boltzmann variable was recently presented. We generalized this relationship to a range of powers and extended the solution to include the saturated zone. As a result, the new solution satisfies the Bruce and Klute equation exactly.

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The general objective of this study was to evaluate the ordered weighted averaging (OWA) method, integrated to a geographic information systems (GIS), in the definition of priority areas for forest conservation in a Brazilian river basin, aiming at to increase the regional biodiversity. We demonstrated how one could obtain a range of alternatives by applying OWA, including the one obtained by the weighted linear combination method and, also the use of the analytic hierarchy process (AHP) to structure the decision problem and to assign the importance to each criterion. The criteria considered important to this study were: proximity to forest patches; proximity among forest patches with larger core area; proximity to surface water; distance from roads: distance from urban areas; and vulnerability to erosion. OWA requires two sets of criteria weights: the weights of relative criterion importance and the order weights. Thus, Participatory Technique was used to define the criteria set and the criterion importance (based in AHP). In order to obtain the second set of weights we considered the influence of each criterion, as well as the importance of each one, on this decision-making process. The sensitivity analysis indicated coherence among the criterion importance weights, the order weights, and the solution. According to this analysis, only the proximity to surface water criterion is not important to identify priority areas for forest conservation. Finally, we can highlight that the OWA method is flexible, easy to be implemented and, mainly, it facilitates a better understanding of the alternative land-use suitability patterns. (C) 2008 Elsevier B.V. All rights reserved.

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Xanthomonas axonopodis pv. passiflorae causes bacterial spot in passion fruit. It attacks the purple and yellow passion fruit as well as the sweet passion fruit. The diversity of 87 isolates of pv. passiflorae collected from across 22 fruit orchards in Brazil was evaluated using molecular profiles and statistical procedures, including an unweighted pair-group method with arithmetical averages-based dendrogram, analysis of molecular variance (AMOVA), and an assigning test that provides information on genetic structure at the population level. Isolates from another eight pathovars were included in the molecular analyses and all were shown to have a distinct repetitive sequence-based polymerase chain reaction profile. Amplified fragment length polymorphism technique revealed considerable diversity among isolates of pv. passiflorae, and AMOVA showed that most of the variance (49.4%) was due to differences between localities. Cluster analysis revealed that most genotypic clusters were homogeneous and that variance was associated primarily with geographic origin. The disease adversely affects fruit production and may kill infected plants. A method for rapid diagnosis of the pathogen, even before the disease symptoms become evident, has value for producers. Here, a set of primers (Xapas) was designed by exploiting a single-nucleotide polymorphism between the sequences of the intergenic 16S-23S rRNA spacer region of the pathovars. Xapas was shown to effectively detect all pv. passiflorae isolates and is recommended for disease diagnosis in passion fruit orchards.

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In this work, supercritical technology was used to obtain extracts from Ocimum basilicum (sweet basil) with CO(2) and the cosolvent H(2)O at 1, 10, and 20% (w/w). The raw material was obtained from hydroponic cultivation. The extract`s global yield isotherms, chemical compositions, antioxidant activity, and cost of manufacturing were determined. The extraction assays were done for pressures of 10 to 30 MPa at 303 to 323 K. The identification of the compounds present in the extracts was made by GC-MS and ESI-MS. The antioxidant activity of extracts was determined using the coupled reaction of beta-carotene and linolenic acid. At 1% of cosolvent, the largest global yield was obtained at 10 MPa and 303 K (2%, dry basis-d.b.); at 10% of cosolvent the largest global yield was obtained at 10 and 15 MPa (11%, d.b.), and at 20% of cosolvent the largest global yield was detected at 30 MPa and 303 K (24%, d.b.). The main components identified in the extracts were eugenol, germacrene-D, epi-alpha-cadinol, malic acid, tartaric acid, ramnose, caffeic acid, quinic acid, kaempferol, caffeoylquinic acid, and kaempferol 3-O-glucoside. Sweet basil extracts exhibited high antioxidant activity compared to beta-carotene. Three types of SFE extracts from sweet basil were produced, for which the estimated cost of manufacturing (class 5 type) varied from US$ 47.96 to US$ 1,049.58 per kilogram of dry extract.

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In stored grains, smaller depositions and great variation with respect to theoretical insecticide doses are frequently found. The objective of this work was to study the effectiveness of the standard method (ISO 5682/1-1996) employed to evaluate hydraulic nozzles used in stored corn and wheat grain protection experiments. The transversal volumetric distribution and droplet spectrum of a model TJ-60 8002EVS nozzle were determined in order to calibrate a spraying system for an application rate of 5 L/t and to obtain theoretical concentrations of 10 and 0.5 mg/kg of fenitrothion and esfenvalerate, respectively. After treatment, the corn and wheat grains were processed and deposition was analyzed by gas chromatography. The type of grain did not have any influence on insecticide deposition and was dependent upon insecticide only. The insecticide deposits on the grains only reached 42.1 and 38.2% of the intended theoretical values for fenitrothion and esfenvalerate concentrations, respectively. These results demonstrate the ineffectiveness of the standard evaluation method for hydraulic nozzles employed in stored grain protection experiments.

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The present investigation is the first part of an initiative to prepare a regional map of the natural abundance of selenium in various areas of Brazil, based on the analysis of bean and soil samples. Continuous-flow hydride generation electrothermal atomic absorption spectrometry (HG-ET AAS) with in situ trapping on an iridium-coated graphite tube has been chosen because of the high sensitivity and relative simplicity. The microwave-assisted acid digestion for bean and soil samples was tested for complete recovery of inorganic and organic selenium compounds (selenomethionine). The reduction of Se(VI) to Se(IV) was optimized in order to guarantee that there is no back-oxidation, which is of importance when digested samples are not analyzed immediately after the reduction step. The limits of detection and quantification of the method were 30 ng L(-1) Se and 101 ng L(-1) Se, respectively, corresponding to about 3 ng g(-1) and 10 ng g(-1), respectively, in the solid samples, considering a typical dilution factor of 100 for the digestion process. The results obtained for two certified food reference materials (CRM), soybean and rice, and for a soil and sediment CRM confirmed the validity of the investigated method. The selenium content found in a number of selected bean samples varied between 5.5 +/- 0.4 ng g(-1) and 1726 +/- 55 ng g(-1), and that in soil samples varied between 113 +/- 6.5 ng g(-1) and 1692 +/- 21 ng g(-1). (C) 2011 Elsevier B.V. All rights reserved.

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This study was conducted to evaluate the natural variability of total, extractable and non-extractable phenolics in pigmented and non-pigmented rice genotypes (Oryza sativa L.) and to estimate whether the contents and distribution of these compounds are typical for genotypes from indica and japonica subspecies. Twenty-one samples of commercial as well as new genotypes of brown rice, including seven pigmented genotypes were obtained from two Agronomic Institutes in South Brazil. Free and conjugated phenolics were extracted with ethanol, while bound phenolics were released by alkaline hydrolysis. Total phenolics were estimated in both fractions by the Folin-Ciocalteau method. Genotypes from Japonica and indica non-pigmented subspecies were not statistically distinguishable from each other, but differences in phenolic contents were associated with pericarp color. Despite individual differences, total phenolics were four times higher in pigmented than in non-pigmented genotypes (4246 and 1073 mg ferulic acid equiv. kg(-1), respectively). These high amounts were mostly due to the presence of extractable (free and conjugated) phenolics, which comprised up to 81% of total phenolics for pigmented genotypes. Non-extractable (bound) phenolics comprised 40% of total phenolics of non-pigmented rice genotypes while pigmented genotypes presented greater absolute amounts, but their contribution on total phenolics was small. (C) 2008 Elsevier Inc. All rights reserved.

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The antioxidant capacity of the striped sunflower seed cotyledon extracts, obtained by sequential extraction with different polarities of solvents, was evaluated by three different in vitro methods: ferric reducing/antioxidant power (FRAP), 2.2-diphenyl-1-picrylhydrazyl radical (DPPH) and oxygen radical absorbance capacity (ORAC) assays. In the three methods, the aqueous extract at 30 mu g/ml showed a higher antioxidant capacity value (FRAP, 45.27 mu mol; DPPH, 50.18%; ORAC, 1.5 Trolox equivalents) than the ethanolic extract (FRAP, 32.17 mu mol; DPPH, 15.21%; ORAC, 0.50 Trolox equivalents). When compared with the synthetic antioxidant butylated hydroxyl toluene, the antioxidant capacity of the aqueous extract varied from 45% to 66%, according to the used method. The high antioxidant capacity observed for the aqueous extract of the studied sunflower seed suggests that the intake of this seed may prevent in vivo oxidative reactions responsible for the development of several diseases, such as cancer.

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Brazilian propolis contains several phenolic compounds among which 5 diprenyl-4-hydroxycinnamic acid (artepillin-C) is commonly found in areas where flora is rich in Baccharis species. The quantification of artepillin-C has become an important factor as an indicator of Brazilian propolis quality and the compound may be used as a chemical marker for quality control in exportating green propolis. This work was to validate the method and evaluate the content of artepillin-C from 33 samples collected in different Brazilian regions. The method used was HPLC with UV-vis detection and a reversed-phase C-18 Column. The validation parameters studied were: linearity, accuracy, precision, quantification and detection limits. The results obtained were: detection limit = 0.0036 mu g/mL, quantification limit = 0.012 mu g/mL, accuracy = 0.0064 and 0.078, recovery 98-102%. Artepillin-C content varied from 0 to 11% depending on the geographical origin. Propolis from the southeast region presented the highest level of artepillin-C (5.0-11.0%). Whist that from the northeast region did not show any artepillin-C. Copyright (C) 2008 John Wiley & Sons, Ltd.

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The extensive use of antineoplastic agents in chemotherapy may be at risk to health care workers involved in the preparation and administration of these drugs. In this study cyclophosphamide, a drug classified as a human carcinogen, was quantified by adapting a previous analytical method using gas chromatography coupled to mass spectrometry (GC-MS) after solid phase extraction with diatomaceous earth. The drug was measured by analysis in surfaces (wipe samples) and gloves, collected from four different hospitals, before and after the practice of cleaning procedures, and the use of a closed-system device for the preparation and administration. Validation results were satisfactory and cyclophosphamide levels ranging from below the quantification limit to 141000 ng. Our findings demonstrated that surfaces and materials contamination was found in all hospitals during the traditional open technique for preparation and administration of cyclophosphamide and a significant reduction in contamination when a closed-system device was used. However, some values were considered unexpected, especially those obtained from samples collected after the cleaning surfaces.