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Ekechukwu Gerald K. Khishvand Mahdi Kuang Wendi Piri Mohammad Masalmeh Shehadeh 《Transport in Porous Media》2021,136(2):369-410
Transport in Porous Media - On the basis of a well-based model (Model I) developed in a previous work (Liu and Valkó in SPE J 2019. https://doi.org/10.2118/197049-PA ), in which a fractional... 相似文献
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Andrew J. Boggess Thomas L. White Mark A. Jones Christopher J. Bannochie Amy A. Ekechukwu William R. Wilmarth 《Journal of Radioanalytical and Nuclear Chemistry》2018,318(1):97-106
Organomercury species are present at regulatory levels in the tanks at the Savannah River Site. Calibration of methylmercury and ethylmercury ranged three orders of magnitude, generating detection limits of 0.033 pg and 7.50 pg, respectively. Calibration verifications maintained 101 and 103% accuracy, respectively, with mean recovery from waste samples of 104%. Dilution volume was optimized to eliminate sample distillation, decreasing method runtime by 337% and reducing total instrumentation footprint by 60.4% compared with current standard methods. Compared with standard methods, this work represents a significant improvement in safety, efficiency, and reproducibility of organomercury speciation, particularly for industrial and nuclear analysis. 相似文献
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R. A. Dewberry W. T. Boyce N . E. Bibler A. E. Ekechukwu D. M. Ferrara 《Journal of Radioanalytical and Nuclear Chemistry》2002,252(3):503-513
This paper describes development work to obtain a product phase of 151Sm pure of any other radioactive species so that it can be determined in US Department of Energy high level liquid waste and low level solid waste by liquid scintillation b-spectroscopy. The technique provides separation from mCi/ml levels of 137Cs, Pu a- and 241Pu b-decay activity, and 90Sr/90Y activity. The separation technique is also demonstrated to be useful for the determination of 147Pm. 相似文献
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Turick CE Ekechukwu AA Milliken CE Casadevall A Dadachova E 《Bioelectrochemistry (Amsterdam, Netherlands)》2011,82(1):69-73
The presence of melanin pigments in organisms is implicated in radioprotection and in some cases, enhanced growth in the presence of high levels of ionizing radiation. An understanding of this phenomenon will be useful in the design of radioprotective materials. However, the protective mechanism of microbial melanin in ionizing radiation fields has not yet been elucidated. Here we demonstrate through the electrochemical techniques of chronoamperometry, chronopotentiometry and cyclic voltammetry that microbial melanin is continuously oxidized in the presence of gamma radiation. Our findings establish that ionizing radiation interacts with melanin to alter its oxidation-reduction potential. Sustained oxidation resulted in electric current production and was most pronounced in the presence of a reductant, which extended the redox cycling capacity of melanin. This work is the first to establish that gamma radiation alters the oxidation-reduction behavior of melanin, resulting in electric current production. The significance of the work is that it provides the first step in understanding the initial interactions between melanin and ionizing radiation taking place and offers some insight for production of biomimetic radioprotective materials. 相似文献
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The presence of stratification is well known to improve the performance of stratified thermal energy storage systems (STESS). The major energy and exergy methods for modeling and assessing the performance of STESS are reviewed in this presentation. Current analytical and numerical methods for modeling STESS are surveyed, with their strengths and weaknesses. An extensive survey of performance assessment methods based on energy, entropy and exergy analyses is also presented. This survey highlights entropy generation ratios, which are based on second law considerations, as effective in quantifying the improvements in STESS performances that result from the presence of stratification unlike energy-based measures. The entropy generation number, N s is suggested as an effective tool for future performance studies on STESS. 相似文献
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