The behavior of an immobilized enzyme reactor utilizing asymmetric hollow fibers is simulated using a theoretical model. In this reactor, an enzyme solution contained within the annular open‐cell porous support structure of the fiber is separated from a substrate flowing through the fiber lumen by an ultrathin dense membrane impermeable to enzyme but permeable to substrate and product. The coupled set of model equations describing the behavior of this reactor represents an extended Graetz problem in the fiber lumen, with diffusion through the ultrathin fiber skin and reaction in the microporous sponge region. Exact analytic expressions for substrate concentration profiles throughout an idealized fiber which incorporate the membrane and hydrodynamic mass transfer resistances are obtained for a first‐order enzyme reaction, and numerical techniques for their evaluation are given. This analysis is extended to yield a numerical finite difference solution for nonlinear Michaelis‐Menten reaction kinetics, which is shown to agree with the analytic solution, as Km/C0, the ratio of the Michaelis constant to the initial substrate concentration, becomes large (> 100).

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Most importantly, all the persons named in this report, and others, from high organizational levels and principal investigators to workers, deserve real praise for the exemplary degree to which each contributed to this multi-organizational and multi-disciplinary team achievement... The three CEMs were tested simultaneously during test periods in which low, medium, and high concentration levels of seven toxic metals -antimony, arsenic, beryllium, cadmium, chromium, lead, and mercury -were maintained under carefully controlled conditions. Two methods were used to introduce the test metals into the flue gas: (1) solution atomization, introducing metalcontaining aerosol directly into the secondary combustion burner, and (2) injection of fly ash particulates. The prototype CEMs were of two types: one using inductively coupled argon plasma -atomic emission spectrometry to excite and determine the toxic metals in an extracted sample of the flue gas; and two systems using LIBS to excite and measure metals in situ in the flue gas. The testing addressed four measures of CEM performance ordinarily checked in a relative accuracy test audit (RATA) as described in 40 CFR 60 Appendix F -relative accuracy (RA), calibration drift, zero drift, and response time -but the primary focus was on the RA measurements. These were accomplished by comparing the toxic metal analyte concentrations reported by the CEMs to the concentrations measured using the EPA reference method (RM) for the same analytes. The tests included at least triplicate F W measurements at each of the three test metals concentrations. ABSTRACTThe ICP-AES system provided quantitative CEM results for the seven toxic metals at all three concentration levels. For the seven metals, the ICP-AES system achieved average relative accuracies of 74,72, and 67% for the low, medium, and high concentration levels, respectively. An RA value of 0% indicates complete agreement between the values measured by the instrument under test and the values determined by the EPA reference method. The RA values achieved by the ICP-AES system ranged between 16% and 143%.The L B S systems provided quantitative CEM results for four toxic metals at the high concentration level, three and two toxic metals, respectively, at the medium concentration level, and only two and one, respectively, at the low concentration level. The DIAL, L B S system achieved average relative accuracies of 152,55, and 65% for the low, medium and high concentration levels, respectively. The DIAL LIBS RA values ranged from 3 1 to 273%. The SNL LIBS system achieved average relative accuracies of 91,241 , and 169% for the low,

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