2,249 research outputs found
Vascular Surgery and Transplantation
Rev Port Cir Cardiotorac Vasc. 2003 Oct-Dec;10(4):215-217.
[Vascular Surgery and Transplantation]
[Article in Portuguese]
Pereira MC.
Abstract
As Honorary President of the Joint Meeting of Portuguese Society for Cardiothoracic and Vascular Surgery and the Portuguese Society of Transplantation, the author addressed a conference in which he emphasized the straigth links existing between Vascular Surgery and Organ Transplantation Surgery, and describes his professional course and the historical development of transplantation in its Department and Hospital, as well as in the remaining country, an area in which he was proeminent protagonist and pionner, leading to his nomination to distinguished functions of National Coordinator of Organ Transplantation in Portugal.
PMID: 15146258 [PubMed - as supplied by publisher
Interfacial tension of reservoir fluids : an integrated experimental and modelling investigation
Interfacial tension (IFT) is a property of paramount importance in many technical areas as it deals with the forces acting at the interface whenever two immiscible or partially miscible phases are in contact. With respect to petroleum engineering operations, it influences most, if not all, multiphase processes associated with the extraction and refining of Oil and Gas, from the optimisation of reservoir engineering strategies to the design of petrochemical facilities. This property is also of key importance for the development of successful and economical CO2 geological storage projects as it controls, to a large extent, the amount of CO2 that can be safely stored in a target reservoir. Therefore, an accurate knowledge of the IFT of reservoir fluids is needed.
Aiming at filling the experimental gap found in literature and extending the measurement of this property to reservoir conditions, the present work contributes with fundamental IFT data of binary and multicomponent synthetic reservoir fluids. Two new setups have been developed, validated and used to study the impact of high pressures (up to 69 MPa) and high temperatures (up to 469 K) on the IFT of hydrocarbon systems including n-alkanes and main gas components such as CH4, CO2, and N2, as well as of the effect sparingly soluble gaseous impurities and NaCl on the IFT of water and CO2 systems. Saturated density data of the phases, required to determine pertinent IFT values, have also been measured with a vibrating U-tube densitometer. Results indicated a strong dependence of the IFT values with temperature, pressure, phase density and salt concentration, whereas changes on the IFT due to the presence of up to 10 mole% gaseous impurities (sparingly soluble in water) laid very close to experimental uncertainties.
Additionally, the predictive capabilities of classical methods for computing IFT values have been compared to a more robust theoretical approach, the Density Gradient Theory (DGT), as well as to experimental data measured in this work and collected from literature. Results demonstrated the superior capabilities of the DGT for accurately predicting the IFT of synthetic hydrocarbon mixtures and of a real petroleum fluid with no further adjustable parameters for mixtures. In the case of aqueous systems, one binary interaction coefficient, estimated with the help of a single experimental data point, allowed the correct description of the IFT of binary and multicomponent systems in both two- and three-phase equilibria conditions, as well as the impact of salts with the DGT
Assessment of ultrafine particles in Portuguese preschools: levels and exposure doses
The aim of this work was to assess ultrafine particles (UFP) number concentrations in different microenvironments of Portuguese preschools and to estimate the respective exposure doses of UFP for 3–5-year-old children (in comparison with adults). UFP were sampled both indoors and outdoors in two
urban (US1, US2) and one rural (RS1) preschool located in north of Portugal for 31 days. Total levels of indoor UFP were significantly higher at the urban preschools (mean of 1.82x104 and 1.32x104 particles/cm3 at US1 an US2, respectively) than at the rural one (1.15x104 particles/cm3). Canteens were the indoor microenvironment with the highest UFP (mean of 5.17x104, 3.28x104, and 4.09x104 particles/cm3 at US1, US2, and RS1), whereas the lowest concentrations were observed in classrooms (9.31x103, 11.3x103, and 7.14x103 particles/cm3 at US1, US2, and RS1). Mean indoor/outdoor ratios (I/O) of UFP at three preschools were lower than 1 (0.54–0.93), indicating that outdoor emissions significantly contributed to UFP indoors. Significant correlations were obtained between temperature, wind speed, relative humidity, solar radiation, and ambient UFP number concentrations. The estimated exposure doses were higher in children attending urban preschools; 3–5-year-old children were exposed to 4–6 times higher UFP doses than adults with similar daily schedules
Development of ternary diagrams for estimating water retention properties using geostatistical approaches
Most pedotransfer functions (PTFs) have adopted soil texture information as the main predictor to estimate
soil hydraulic properties, whether inputs are defined in terms of the relative proportion of different grain size
particles or texture-based classifications. The objective of this studywas to develop ternary diagrams for estimating
soil water retention (θ) at−33 and−1500 kPa matric potentials, corresponding to the field capacity and wilting
point, respectively, from particle size distribution using two geostatistical approaches. The texture triangle was
divided into a 1% grid of soil texture composition resulting in 4332 different soil textures. Measured soil water
retention values determined in 742 soil horizons/layers located in Portugal were then used to develop and
validate the hydraulic ternary diagrams. The development subset included two-thirds of the data, and the
validation subset the remaining samples. The measured soil water content values were displayed in the ternary
diagram according to the coordinates given by the particles size distribution determined in the same soil
samples. The volumetric water content values were then predicted for the entire ternary diagram using two
different geostatistical interpolation algorithms (ordinary kriging and the empirical best linear unbiased
predictor). Uncertainty analysis resulted in a root mean square error below 0.040 and 0.034 cm3 cm−3 when
comparing the interpolated water contents at −33 and −1500 kPa matric potential values, respectively, with
the measured ones included in the validation dataset. The estimation variance calculated with both methods
was also considered to access the uncertainty of the predictions. The available water content of Portuguese
soils was then derived from θ−33 kPa and θ−1500 kPa ternary diagrams developed with both approaches. The
hydraulic ternary diagrams may thus serve as simplified tools for estimating water retention properties from
particle size distribution and eventually serve as an alternative to the traditional statistical regression and data
mining techniques used to derive PTFsinfo:eu-repo/semantics/publishedVersio
Changes in carbon stocks in Eucalyptus globulus Labill. plantations induced by different water and nutrient availability
Changes in the carbon stocks under different soil water and nutrient conditions were studied in Eucalyptus globulus Labill.
stands in a field experiment, at O ´ bidos (central Portugal). The treatments were irrigation plus a complete fertiliser solution to
simulate ‘near optimal’ nutrition (IF), irrigation only (I), and fertilisers added to rain-fed plots (F). The control (C) received
neither water nor fertilisers (except a small amount at planting). The production of biomass (aboveground), the litterfall and the
soil chemical composition were evaluated regularly during the experiment. Root biomass was estimated at the end of the
experiment. Carbon in biomass, litterfall and soil, increased significantly when water and/or nutrients were supplied, in
comparison to the control. The amount of carbon accumulated in the system, 6 years after planting, was 8.22, 10.22, 11.23 and
13.76 kg C m 2 in the control, F, I and IF treatments, respectively. The increase of carbon in the system during the same period
was 5.86, 7.86, 8.87 and 11.40 kg C m 2 in the control, F, I and IF treatments, respectively. This rise in carbon resulted from the
accumulation of long-lived woody biomass, which represented between 77.7 (in IF) and 82.9% (in the control) of the total rise in
carbon. Although water was the main limiting factor for biomass accumulation, the allocation of carbon to the soil was mainly
related to nutrient supply, irrespective of water availability. The amount of carbon stored belowground, i.e. soil and forest floor,
plus stumps and roots, reached 4.2, 4.7, 4.8 and 6.3 kg C m 2 in the control, F, I and IF treatments, respectively. The increase in
C in the mineral soil regarding the initial state was, in the same order as above, 0.21, 0.75, 0.58 and 1.21 kg C m 2. These values
were 3.6, 9.6, 6.6 and 10.6% of the C accumulated in the whole system, during the experimental period
Impact of dietary plant protein levels on the consumer acceptability of senegalese sole (Solea senegalensis Kaup, 1858)
The aim of the present work was to assess the impact of different vegetable diets in the sensory
acceptability of Senegalese sole.This work was carried out by Project PROAMBIENTE for enhancing SMEs organizational and management structure
to enter foreign markets. PROAMBIENTE has the financial support of Quadro de Referência Estratégico Nacional –
QREN and Programa Operacional Regional do Norte – ON2, supported by the European fund for regional
development FEDER
Avaliação do efeito de campos eléctricos pulsados no rendimento e na presença de compostos bioactivos no azeite virgem.
Avaliação do efeito de campos eléctricos pulsados no rendimento e na presença de compostos bioactivos no azeite virgem.info:eu-repo/semantics/publishedVersio
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