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.
This work reports the study of the combination of soil vapor extraction (SVE) with bioremediation (BR) to
remediate soils contaminated with benzene. Soils contaminated with benzene with different water and
natural organic matter contents were studied. The main goals were: (i) evaluate the performance of SVE
regarding the remediation time and the process efficiency; (ii) study the combination of both technologies
in order to identify the best option capable to achieve the legal clean up goals; and (iii) evaluate the
influence of soil water content (SWC) and natural organic matter (NOM) on SVE and BR.
The remediation experiments performed in soils contaminated with benzene allowed concluding that:
(i) SVE presented (a) efficiencies above 92% for sandy soils and above 78% for humic soils; (b) and remediation
times from 2 to 45 h, ...
Gastrointestinal (GI) cancer is one of most common cause of cancer
-
related death over
the world. Its detection at its earliest stage
is crucial to increase the patient survival chances(1).
Optical signals extraction and analysis, specifically diffuse reflectance and intrinsic fluorescence, may
improve the ability to detect GI dysplasia, once some morphological and biochemical changes on the
tissues (related with
early
cancer progression) can modify these signals’ shape and intensity(2, 3). The
project under this paper aims to develop a chip sized spectroscopy microsystem for the early detection
of GI cancer. This paper presents the characterization of silicon photodiodes(n+/p-epilayer type)
fabricated in a standard 0.7μm
CMOS process, with different dimensions.
The main goal ...
The extraction of the exopolymeric matrix is a prerequisite to properly assessing the composition of
the biofilm. Several extraction methods have already been 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, were 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 sonicat...
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.
Brewers´ spent grain (BSG) is a by-product from beer industry that can be exploited as a source of
arabinoxylo-oligosaccharides (AXOS) with prebiotic activity. In this study, microwave-assisted extractions were
performed during 2 min at 140-210°Cin order to evaluate the feasibility of this extraction technology for quantitative
extraction of the arabinoxylans (AX) or AXOS from BSG. The AX yield increasedwith the increase of the temperature
in the range used. The best condition of extraction of the AXwas 210 ºC during 2 min, allowing the extraction of 43%
of total AX. These AX showed structural variability which allow to define specific types of compounds for different
applications and uses depending on the extraction conditions used.
Different parameters as temperature, pressure, solvent mass and sample granulometry governing the extraction yield of tagitinin C from the aerial parts of Tithonia diversifolia were optimised.
The supercritical fluid extraction (SFE) of liquids and solid materials is gaining increasing interest and commercial application in last decades, most particularly under the recent concept of green chemistry and biorefinery. Hence, it is fundamental to provide adequate modeling of the SFE, in order to optimize operating conditions and simulate the global process. This work intends to review the most significant and physically sound models published in the literature for countercurrent liquid-supercritical fluid extraction and SFE of solid matrices, such as the linear driving force, shrinking core, broken and intact cells, and the combination of BIC and shrinking core models. The main assumptions and mass transfer expressions are presented and discussed. (C) 2010 The Institution of Chemical Engineers. Published by Elsevier B.V. All rig...
Abstract publicado na página 172 do livro "7º Encontro Nacional de Cromatografia", do Departamento de Química e Bioquímica da Faculdade de Ciências da Universidade do Porto; ISBN: 978-989-97667-0-9
Thesis submitted to Faculdade de Ciências e Tecnologia of the Universidade Nova de Lisboa, in partial fulfilment of the requirements for the degree of Master in Computer Science
Airflow rate is one of the most important parameters for the soil vapor extraction of contaminated sites,
due to its direct influence on the mass transfer occurring during the remediation process. This work
reports the study of airflow rate influence on soil vapor extractions, performed in sandy soils contaminated
with benzene, toluene, ethylbenzene, xylene, trichloroethylene and perchloroethylene. The objectives
were: (i) to analyze the influence of airflow rate on the process; (ii) to develop a methodology to
predict the remediation time and the remediation efficiency; and (iii) to select the most efficient airflow
rate. For dry sandy soils with negligible contents of clay and natural organic matter, containing the contaminants
previously cited, it was concluded that: (i) if equilibrium between the pollutants and the different...
