Analysis of tracer experiments in non-conservative steady-state systems

1955 ◽  
Vol 17 (2) ◽  
pp. 87-94 ◽  
Author(s):  
H. E. Hart
Keyword(s):  
Steady State ◽  
Tracer Experiments

scholarly journals Estimates of Michaelis-Menten Constants for the Two Membranes of the Brain Endothelium

1984 ◽  
Vol 4 (2) ◽  
pp. 241-249 ◽  
Author(s):  
Albert Gjedde ◽  
Ove Christensen
Keyword(s):  
Steady State ◽  
Endothelial Cell ◽  
Transport Properties ◽  
Glucose Transport ◽  
Cell Membranes ◽  
Experimental Studies ◽  
Facilitated Diffusion ◽  
Capillary Endothelial Cells ◽  
The Individual ◽  
Tracer Experiments

Tracer studies on facilitated diffusion across the blood–brain barrier lead to the calculation of Michaelis-Menten constants that describe the rate of transport. However, the barrier consists of two endothelial cell membranes, and the relevance of single Michaelis-Menten constants in relation to the two cell membranes is unknown. We have formulated a model of two endothelial cell membranes and show that the measured Michaelis-Menten constants are simple functions of the properties of the individual membranes when transport across the endothelium is rapid ( P1 > 10−6 cm s−1). We also show that the Michaelis-Menten constants determined in tracer experiments describe facilitated diffusion in the steady state only if the two membranes have similar transport properties. As an application of this observation, we have examined three experimental studies that measure glucose transport in the steady state and show that the Michaelis-Menten constants for glucose transport calculated from the tracer experiments are equal to the constants calculated from the steady-state experiments. We conclude that the luminal and abluminal membranes of brain capillary endothelial cells have equal glucose transport properties.

Transport of bromide in the Bainsvlei soil: Field experiment and deterministic/stochastic model simulation. II. Intermittent water application

Soil Research ◽  
2005 ◽  
Vol 43 (1) ◽  
pp. 81 ◽  
Author(s):  
Ketema Tilahun ◽  
J. F. Botha ◽  
A. T. P. Bennie
Keyword(s):  
Steady State ◽  
Model Simulation ◽  
Soil Core ◽  
Water Fluxes ◽  
Water Application ◽  
Concentration Data ◽  
Average Pore ◽  
Continuous Application ◽  
Average Dispersion ◽  
Tracer Experiments

Despite the fact that non-uniform soil water content and variable input water fluxes are usually encountered in the field, tracer experiments have usually been carried out under steady-state conditions. The objective of this study was to analyse solute transport in a Bainsvlei soil under intermittent water application using Br– as a tracer. Sprinkler was used to apply water on a plot 200 by 200 cm. Soil core samples were taken every 20 cm to a depth of 160 cm several times during the experiment. The soil Br– concentration data were fitted to the steady-state convection–dispersion analytical model in the CXTFIT package. The average coefficients of determination yielded by this fit (r2 = 0.810) clearly support that the data could be analysed successfully with CXTFIT. The average pore-water velocity of 1.72 cm/day and average dispersion coefficient of 26.19 cm2/day determined from this fit are lower than the fitted values of the steady-state experiments. The Br– moved slower under the intermittent application of water than in the steady case, a conclusion supported by the deeper location of Br– peaks under continuous application than intermittent application after the same amount of water is applied.

scholarly journals Identifiability of Regional Fluxes From Steady State Tracer Experiments

1997 ◽  
Vol 30 (2) ◽  
pp. 243-246
Author(s):  
Daniele Seno ◽  
Gianna Toffolo ◽  
Claudio Cobelli
Keyword(s):  
Steady State ◽  
Regional Fluxes ◽  
Tracer Experiments

Estimation of steady-state flux rates in metabolic systems by computer simulations of radioactive tracer experiments

1993 ◽  
Vol 9 (5) ◽  
pp. 573-580
Author(s):  
Hermann-George Holzhütter ◽  
Anke Schwendel ◽  
Tilman Grune ◽  
Jörn Quedenau ◽  
Werner Siems
Keyword(s):  
Steady State ◽  
Computer Simulations ◽  
Radioactive Tracer ◽  
Steady State Flux ◽  
Metabolic Systems ◽  
Tracer Experiments

Analysis of steady-state carbon tracer experiments using akaike information criteria

Metabolomics ◽  
2021 ◽  
Vol 17 (7) ◽  
Author(s):  
Jeffry R. Alger ◽  
Abu Minhajuddin ◽  
A. Dean Sherry ◽  
Craig R. Malloy
Keyword(s):  
Steady State ◽  
Information Criteria ◽  
Akaike Information Criteria ◽  
Tracer Experiments

Studies on Water in the Hydration Chamber of a Modified Electron Microscope

1970 ◽  
Vol 28 ◽  
pp. 544-545
Author(s):  
R. C. Moretz ◽  
G. G. Hausner ◽  
D. F. Parsons
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Electron Microscope ◽  
Steady State ◽  
Room Temperature ◽  
Small Mass ◽  
Equilibrium Pressure ◽  
Biological Objects ◽  
Mechanical Pump ◽  
Differential Pumping

Use of the electron microscope to examine wet objects is possible due to the small mass thickness of the equilibrium pressure of water vapor at room temperature. Previous attempts to examine hydrated biological objects and water itself used a chamber consisting of two small apertures sealed by two thin films. Extensive work in our laboratory showed that such films have an 80% failure rate when wet. Using the principle of differential pumping of the microscope column, we can use open apertures in place of thin film windows.Fig. 1 shows the modified Siemens la specimen chamber with the connections to the water supply and the auxiliary pumping station. A mechanical pump is connected to the vapor supply via a 100μ aperture to maintain steady-state conditions.

Continuous hydrogenolysis of acetal-stabilized lignin in flow

2021 ◽  
Author(s):  
Wu Lan ◽  
Yuan Peng Du ◽  
Songlan Sun ◽  
Jean Behaghel de Bueren ◽  
Florent Héroguel ◽  
...  
Keyword(s):  
Steady State ◽  
Challenges And Opportunities

We performed a steady state high-yielding depolymerization of soluble acetal-stabilized lignin in flow, which offered a window into challenges and opportunities that will be faced when continuously processing this feedstock.

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