Application of diffusive transport model for better insight into retardation mechanisms involved in ion-imprinted membrane transport

Drug-eluting stents (DESs) perform their antiproliferative effects through the use of localized drug delivery. The delivery may be computationally modeled to determine efficacy of the DES-tissue system and utilizes coupled convective and diffusive transport. Since the movement of solutes through the wall is via the coupled effects of convective and diffusive transport, the relative influence of these factors provides insight into the governing forces of localized DES drug delivery [1].

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Radial Mixing in an Axial Turbine

Volume 1: Turbomachinery ◽

10.1115/94-gt-137 ◽

1994 ◽

Cited By ~ 1

Author(s):

Robert P. Dring

Keyword(s):

Secondary Flow ◽

Transport Model ◽

Good Prediction ◽

Diffusive Transport ◽

Axial Turbine ◽

Mixing Coefficient ◽

Coefficient Distribution ◽

Calculated Profile ◽

Flow Velocities

The objective of this work was to examine radial mixing in an axial turbine from a number of different perspectives. These include: (1) its impact on the spanwise distributions of the force on the airfoils and the change in the fluid momentum as it passed between them, (2) the mixing coefficient distribution based on measured secondary flow velocities, and (3) comparisons of measured and calculated profile redistribution for an axisymmetric inlet profile and for profiles generated by introducing hot and cold streaks upstream of the turbine. It was seen that a simple diffusive transport model could give a good prediction of most of the measured results.

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Temperature response measurements from eucalypts give insight into the impact of Australian isoprene emissions on air quality in 2050

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-6193-2020 ◽

2020 ◽

Vol 20 (10) ◽

pp. 6193-6206

Author(s):

Kathryn M. Emmerson ◽

Malcolm Possell ◽

Michael J. Aspinwall ◽

Sebastian Pfautsch ◽

Mark G. Tjoelker

Keyword(s):

Air Quality ◽

Transport Model ◽

Temperature Response ◽

Emission Factors ◽

Eucalyptus Species ◽

Chemical Transport Model ◽

Mixing Ratios ◽

The Impact ◽

Temperature Responses ◽

Insight Into

Abstract. Predicting future air quality in Australian cities dominated by eucalypt emissions requires an understanding of their emission potentials in a warmer climate. Here we measure the temperature response in isoprene emissions from saplings of four different Eucalyptus species grown under current and future average summertime temperature conditions. The future conditions represent a 2050 climate under Representative Concentration Pathway 8.5, with average daytime temperatures of 294.5 K. Ramping the temperature from 293 to 328 K resulted in these eucalypts emitting isoprene at temperatures 4–9 K higher than the default maximum emission temperature in the Model of Emissions of Gases and Aerosols from Nature (MEGAN). New basal emission rate measurements were obtained at the standard conditions of 303 K leaf temperature and 1000 µmol m−2 s−1 photosynthetically active radiation and converted into landscape emission factors. We applied the eucalypt temperature responses and emission factors to Australian trees within MEGAN and ran the CSIRO Chemical Transport Model for three summertime campaigns in Australia. Compared to the default model, the new temperature responses resulted in less isoprene emission in the morning and more during hot afternoons, improving the statistical fit of modelled to observed ambient isoprene. Compared to current conditions, an additional 2 ppb of isoprene is predicted in 2050, causing hourly increases up to 21 ppb of ozone and 24-hourly increases of 0.4 µg m−3 of aerosol in Sydney. A 550 ppm CO2 atmosphere in 2050 mitigates these peak Sydney ozone mixing ratios by 4 ppb. Nevertheless, these forecasted increases in ozone are up to one-fifth of the hourly Australian air quality limit, suggesting that anthropogenic NOx should be further reduced to maintain healthy air quality in future.

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Use of experimental isotope-exchange fluxes in reversible enzyme and membrane transport models, assessed by simultaneous computer simulation of unidirectional and net chemical rates

Biochemical Journal ◽

10.1042/bj2860295 ◽

1992 ◽

Vol 286 (1) ◽

pp. 295-303 ◽

Cited By ~ 2

Author(s):

I W Plesner

Keyword(s):

Steady State ◽

Exchange Rates ◽

Membrane Transport ◽

Isotope Exchange ◽

Transport Model ◽

Total Concentration ◽

Rate Equations ◽

Tracer Transport ◽

Transport Models ◽

Experimental Conditions

Steady-state rate equations for unidirectional (isotope-exchange) rates can become so complex, even for rather simple (reversible) enzyme or membrane transport models, that they are useless for detailed data analysis. In this paper a procedure is described for simultaneous simulation of net (chemical) and isotope-exchange rates. The method employs an expanded version of the basic model to monitor explicitly the fate of the label in an experiment. The procedure is quite general, and can be used for steady-state as well as transient kinetic situations, or it can be used in conjunction with existing interactive computer programs for steady-state model analysis. Three numerical examples are presented. First, it is shown, using the conventional (Post-Albers) model for Na+/K(+)-ATPase, that the change in concentration of a labelled intermediate after a change in experimental conditions does not in general reflect the change in the total concentration of that intermediate, and thus labelled intermediate concentrations may be misleading. Second, using a standard co-transport model and a prototype active-transport model (equivalent to a ligand-ATPase), it is shown that the ratio of tracer transport fluxes at steady state yields transport stoichiometries which depend on the experimental conditions, are different from the net apparent stoichiometries, and whose changes with conditions are also different from that of the net stoichiometries. It follows that conclusions drawn on the basis of experimentally determined tracer fluxes should be viewed with some caution. Specifically, a measured influx stoichiometry ligand/ATP (in the ATPase case) of higher than 1:1 does not necessarily imply the existence of more than one site for either ligand on the enzyme.

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