A leitura como um processo cognitivo
Figueiredo, Olívia Maria
1999-01-01
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You search for extraction and 8,991 records were found.
Vine pruning residue (VPR) is a by-product obtained after annual pruning of vines, abundant in Portugal, and a natural source of compounds with antioxidant activity. In a previous work, an integral valorization of this residue was proposed in which 13.7 kg of xylooligosaccharides, 3.1 kg of phenolic compounds, 13.1 kg of ethanol and 27 kg of lignin per 100 kg of vine pruning residue were extracted[1]. Here, we aim at optimizing antioxidants extraction using different fractions of organic solvent (ethanol / water).
Therefore, the objective of this work was to attain an optimum extraction condition for polyphenolic compounds from grapevine pruning using a response surface methodology. For each assay the temperature (46-114°C), the extraction time (19-221 min) and ethanol concentration (30-70%) were determined by factorial design. The s...
Aims: To compare three methods for DNA extraction from Mycobacterium
bovis, Mycobacterium tuberculosis and Mycobacterium avium subsp. avium.
Methods and Results: The DNA was extracted from mycobacterial cultures
using enzymatic extraction, combined bead beating and enzymatic extraction
and cetyltrimethylammonium bromide (CTAB) extraction. The yield and quality
of DNA were compared by spectrophotometry, agarose gel electrophoresis,
restriction endonuclease analysis and PCR. The combined bead beating and
enzymatic extraction method yielded more DNA. However, that method produced
some sheared DNA, visible either by agarose gel electrophoresis or by
restriction endonuclease analysis. All methods were appropriate for PCR amplification
of a 123 bp fragment of IS6110 in M. bovis and M. tuberculosis, and of
a 1700 bp fragment of FR300 region i...
Many municipal activities require updated large-scale maps that include both topographic and thematic information. For this
purpose, the efficient use of very high spatial resolution (VHR) satellite imagery suggests the development of approaches that enable
a timely discrimination, counting and delineation of urban elements according to legal technical specifications and quality standards.
Therefore, the nature of this data source and expanding range of applications calls for additional methods and metrics to assess the
quality of the extracted information which go beyond traditional thematic accuracy alone. The present work concerns the feasibility
of VHR satellite imagery as an alternative source of geospatial information for large scale mapping to assist urban planning in
Portugal. Feature extraction software was employed to map bui...
Lisbon is both a historical and modern city having a dynamic landscape, where increasingly diverse urban forms and materials coexist. This complex reality is possibly causing the feature extraction process from imagery to become more challenging. This study tests the semi-automated extraction of buildings from a QuickBird image in urban areas with different characteristics, and explores the impact of the heterogeneity of these features in the extraction process. Spatial metrics are used to characterize types of buildings present in the study areas. Results show that the study areas display different levels of heterogeneity even for the same type of building and suggest that the extraction may be affected by the spatial configuration of target features.
Microbial degradation of fluorinated pharmaceuticalsduring wastewater treatment
processes remains inadequate in most situations. Due to incomplete elimination, these residues are continually being introduced into the aquatic environments in which they settle throughout time since many of them are resistant to degradation. Fluoroquinolone antibiotics due to its persistence and implication on resistant-bacteria development, pose special interest in environmental analysis. Due to their zwitterionic characteristics, the extraction/pre-concentration
process of fluoroquinolones prior analyses is an unquestionable challenge. This work compares the solid phase extraction efficiency of four fluoroquinolones (Ofloxacin, Norfloxacin, Ciprofloxacin and Moxifloxacin) from wastewater effluents by different commercial sorbents.
Prior to wastewa...
The combination of pre-treatments with natural matrices processing may induce higher
extraction yields andlor reduce the treatment times involved. In this essay, the
application of a high pressure treatment prior to the supercritical fluid extraction of grape seed (Vitis vinifera) oil has been investigated.
Experiments show that, under the operating conditions adopted, the final extraction
yield slightly decreases with increasing processing pressure. Up til1 3000 bar such
effect is negligible, though a variation of 15.5% was measured at 5000 bar.
With respect to the supercritical fluid extraction results, the comparison between
cumulative curves achieved with treated and untreated grape seed evidenced faster
kinetics in the former case, despite final yields were approximately the same.
Therefore, combining a high pressure treatment wit...
Nordihydroguaiaretic acid (NDGA) is a powerful antioxidant that can be found in plants like
Larrea tridentata (Zygophyllaceae), also known as creosote bush, which grows in semidesert
areas of Southwestern United States and Northern Mexico [1]. Several studies have
demonstrated that NDGA has important biological activities with great interest in the health area,
such as antiviral, cancer chemopreventive, and antitumorgenic activities [2]. Extraction of
bioactive compounds from plants is conventionally performed using a heat‐reflux extraction
method. However, different techniques have been developed in order to decrease extraction
time and solvent consumption, as well as to increase the extraction yield and enhance the
extracts quality [3]. The objective of this study was to develop a microwave‐assisted extraction
(MAE) method f...
The extraction of the exopolymeric matrix is a prerequisite to properly study the composition of the biofilm. Several
extraction methods were already developed, however no universal method has yet been adopted because the
compromise between high yields of extraction and minimum cell lysis is difficult to establish. In fact, most of the
extraction methods promote leakage of intracellular material. The most common extraction methods, Dowex resin
and sonication, where assayed in biofilms of Pseudomonas fluorescens and Alcaligenes denitrificans submitted to
a pre-treatment with glutaraldehyde (GTA). The assessment of ATP released after extraction was used as a criterion
of cell lysis. The results showed that GTA is a protective agent against cell lysis. The pre-treatment with GTA is
particularly useful combined with sonication.
Mushrooms are appreciated worldwide, not only for their nutritional value and exquisite flavor and
texture, but also for their medicinal properties. There is scientific evidence demonstrating the benefits
of mushrooms ingestion due to their richness in bioactive compounds such as mycosterols, in
particular ergosterol [1]. Agaricus bisporus L. is the most consumed mushroom worldwide presenting
a high content of ergosterol, which represents 90% of its sterol fraction [2]. Thus, it is an interesting
matrix to obtain ergosterol, a molecule with a high commercial value. According to literature,
ergosterol concentration can vary between 3 and 9 mg per g of dried mushroom. Traditional methods
such as maceration and soxhlet extraction are being replaced by emerging methodologies such as
ultrasound assisted extraction in order to decrea...
The control of the microbiological quality of bivalve molluscs assumes particular importance because they are among the most produced seafood products and mostly consumed as a whole, raw, or lightly cooked. The composition of the bacterial community associated with bivalves depends mostly on the microbiology of the surrounding environment at growing sites. Once the relationship between microbiology of bivalves and environment is established, a better classification and monitoring of the shellfish beds and evaluation of depuration strategies can be achieved. In this work, we tested if the methods of DNA extraction commonly used for the culture-independent microbiological analysis of sediment and water could be used directly, or with modifications, for the analysis of bacteria in mussels. The commercial kits Genomic DNA Purification Kit ...
