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Effect of Common Vasodilators on Lung Microvascular PermeabilitySwanson, J. A., Kern, D. F. 01 January 1993 (has links)
The effect of papaverine on the albumin permeability-surface area product (PS), reflection coefficient (σ), and capillary filtration coefficient (K(f)) was examined in isolated rabbit lungs. Because PS and K(f) are functions of vascular surface area and permeability, we also compared papaverine with two other means of maximizing lung surface area: isoproterenol (1 x 10-7 M) and a mild increase in vascular pressure. Only lungs perfused with 0.1 mg/ml papaverine were significantly different from control. PS increased from control (2.80 ± 0.16 to 5.53 ± 0.20 ml · min-1 · g dry lung-1 x 10-2), whereas σ decreased from control (0.92 ± 0.01 to 0.78 ± 0.03). K(f) after papaverine was significantly lower than baseline predrug K(f) (5.60 ± 0.78 to 4.56 ± 0.53 ml · s-1 · cmH2O-1 · g dry lung-1 x 10-3). However, this group's predrug K(f) was higher than that of any other group. Our results indicate that papaverine increases albumin permeability and decreases endothelial selectivity. The isolated perfused lung appears fully recruited, because K(f) and PS did not increase with isoproterenol or increased vascular pressure. Papaverine should be used with caution in the Ringer-perfused lung.
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[en] NUMERICAL STUDY OF LOSS OF INJECTIVITY IN ROCK / [pt] ESTUDO NUMÉRICO DE DECLÍNIO DE INJETIVIDADE EM ROCHAFLAVIO ALCHAAR BARBOSA 24 February 2003 (has links)
[pt] Esta dissertação apresenta um estudo numérico, utilizando
o
método dos elementos finitos, para simular o entupimento
de
rochas provocado pela injeção de água contendo partículas
sólidas. Dentre os diferentes parâmetros que afetam o
declínio de injetividade, quatro foram analisados,
considerando-se a situação de fluxo unidimensional: fator
de dano, concentração de partículas sólidas presentes no
fluido de injeção, coeficiente de filtragem e taxa de
injeção. Um estudo paramétrico ressaltando a influência
destes fatores na perda de injetividade é também
apresentado neste trabalho, concluindo-se que os
resultados
numéricos obtidos concordam satisfatoriamente com as
observações experimentais disponíveis e soluções
analíticas
publicadas na literatura. O trabalho estuda também
numericamente a simulação do entupimento dos poros
da rocha considerando dois modelos de redução de
permeabilidade e recupera valores do coeficiente de
filtragem (Lambda ) e do fator de dano ( Beta ) através
de
análises inversa pelo método dos elementos finitos. / [en] This dissertation presents a numerical study, based on the
finite element method, to simulate rock pore plugging
caused by the injection of water containing solid particles
in suspension. Amongst the parameters that affect rock
injectivity decline, the following four were analyzed,
considering undimensional flow: damage coefficient, solid
particle concentration present in the injection fluid,
filtration coefficient and injection rate. A parametric
study standing out the influence of the these factors in
the loss of injectivity is also presented in this
work, concluding that the numerical results agree
satisfactorily with the available experimental data and
analytical solutions published in the literature. This work
also numerically investigates the process of rock pore
plugging considering two different permeability reduction
models and recovers values of the filtration coefficient
(Lambda ) and the damage factor ( Beta ) through inverse
analyses carried outn by the finite element method.
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