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Recovery Factor (recovery + factor)

Distribution by Scientific Domains

Chemistry	40%

Selected Abstracts

Recovery Factors Affecting Utilization of Small Pediatric Donor Kidneys

AMERICAN JOURNAL OF TRANSPLANTATION, Issue 1 2009
L. K. Kayler
Kidneys from small pediatric donors are underutilized. Using data from the Scientific Registry of Transplant Recipients for donors <21 kg in which at least one organ was recovered from 1997 to 2007 (n = 3341), donor and recovery factors were evaluated by multivariate analysis for associations with (a) kidney nonrecovery and (b) transplantation of recovered kidneys. Results: The proportion of kidney recoveries were 55% during liver procurements and 40% during intestine procurements amongst donors <10 kg (p < 0.01) compared to 93% and 88%, respectively, for donors weighing 10,20 kg (p = 0.003). Intestine procurement was independently associated with an 81% greater likelihood of kidney nonrecovery (p < 0.0001) and a 48% lower likelihood of transplantation (p = 0.0004). A multivariate Cox model indicated that single kidney recipients had a 63% higher risk of graft failure compared with en bloc kidney recipients (p < 0.0001); however, concurrent intestine recovery was not a significant risk factor for graft loss. Intestine recovery from donors <21 kg of age is strongly associated with higher kidney nonrecovery and lower transplantation rates. Graft survival is worse with single kidney transplantation, but is not significantly affected by intestine recovery. Small pediatric donors procurement teams should strive to increase kidney recoveries overall and en bloc recoveries in particular. [source]

Computational study of staged membrane reactor configurations for methane steam reforming.

AICHE JOURNAL, Issue 1 2010

Abstract This article and Part II report a computational study carried out to analyze the performance achievable using a staged membrane reactor in the methane steam reforming process to produce high purity hydrogen. A reaction/separation unit in which reactive stages are laid out in series to permeative stages already proposed in literature (Caravella et al., J Memb Sci. 2008;321:209,221) is modified here to increase its flexibility. The improvement includes the consideration of the Pd-based membrane along the entire length. Two- and ten-staged reactors are examined in terms of methane conversion, hydrogen recovery factor and hydrogen recovery yield, considering co- and counter-current flow configurations. Individual stage lengths are obtained by maximizing either methane conversion or hydrogen recovery yield, comparing the results to the ones of an equivalent traditional reactor and a conventional membrane reactor. The analysis allows demonstrating that the counter-current configuration leads to significant improvements in the hydrogen recovery, but proves almost irrelevant with respect to methane conversion. The influence of the number of stages and the amount of catalyst is quantified in the accompanying part II article. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source]

Effect of surface defects in Pd-based membranes on the performance of a membrane reactor

ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2010
Alessio Caravella
Abstract In this work, the influence of superficial defects over the surface of a Pd-based membrane is analyzed in a membrane reactor for the methane steam-reforming process. In order to include the presence of defects in the permeation, a previous model of a defect-free Pd-based membrane reactor is extended and integrated to include a variable portion of area with defects in the form of pinholes. As a consequence, two different permeation mechanisms are taken into account, one through the Pd-based surface and the other one through the pinholes, where a Knudsen-like transport is considered to occur. The presence of the Knudsen transport causes the membrane separation factor between the hydrogen and the other species involved in the process to decrease, affecting the reactor performances significantly. Three reactor performance indices are investigated as functions of the fraction of the defected area and the mean pore diameter of defects, namely methane conversion, the hydrogen recovery factor, the hydrogen recovery yield and the net purity of hydrogen in the permeate. The results show that the hydrogen recovery factor is positively influenced by the decrease in hydrogen selectivity, whilst methane conversion and hydrogen net purity decrease significantly with it. On the contrary, regarding the hydrogen recovery yield, it is shown that in certain conditions (low furnace temperature, , 550 °C) it decreases with hydrogen selectivity. However, it increases again at higher furnace temperatures (,650 °C). Globally, this investigation helps in identifying acceptable defect levels on a Pd-based membrane for methane steam-reforming applications and highlights that even a very small defect level (in terms of the pinhole diameter and/or amount of the defected area) can importantly compromise the reactor performances. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source]

A review of upstream development policies in Kuwait

OPEC ENERGY REVIEW, Issue 4 2004
Abdulaziz E. Al-Attar
Since 1993, Kuwait's legislative bodies have been looking closely at the prospect of opening-up the country's upstream oil sector for development and production to international oil companies (IOCs). The country has proposed doing this by means of a mechanism called an "operating service agreement" (OSA). This has generated controversy. One side argues that opening-up the oil sector embodies a pattern of denationalisation and is reminiscent of the country's former concession agreement of 1934. And the other side maintains that the proposed OSA is unquestionably different to the concession agreement, in terms of legal framework, fiscal system and the role of the state. This paper reviews and compares the two types of agreement. It then discusses the impact of improved oil recovery factors on increasing oil reserves and production in the northern and western Kuwaiti oil fields, by transferring technology from industrialised countries. [source]