A method for calculating the mean residence times of catenary metabolites

1991 ◽  
Vol 12 (5) ◽  
pp. 335-342 ◽  
Author(s):  
Haiyung Cheng
Keyword(s):  
Residence Times ◽  
The Mean ◽  
Mean Residence Times

Symbolic Equation for the Instantaneous Amount of Substance in Linear Compartmental Systems

2011 ◽  
pp. 348-379
Author(s):  
J.M. Villalba ◽  
R. Varón ◽  
E. Arribas ◽  
R. Diaz-Sierra ◽  
F. Garcia-Sevilla ◽  
...  
Keyword(s):  
Time Course ◽  
Open Systems ◽  
Residence Times ◽  
Transient Phase ◽  
State Equations ◽  
Amount Of Substance ◽  
The Mean ◽  
Symbolic Equation ◽  
Mean Residence Times ◽  
User Friendly

The symbolic time course equations corresponding to a general model of a linear compartmental system, closed or open, with or without traps and with zero input are presented in this chapter. From here, the steady state equations are obtained easily from the transient phase equations by setting the time towards infinite. Special attention is given to the open systems, for which an exhaustive kinetic analysis has been developed to obtain important properties. Besides, the results are particularized to open systems without traps. The software COEFICOM, easy to use and with a user-friendly format of the input of data and the output of results, allows the user to obtain the symbolic expressions of the coefficients involved in the general symbolic equation and all the information necessary to derive the symbolic time course equations for closed or open systems as well as for the derivation of the mean residence times.

scholarly journals Pharmacokinetics and tissue residue of toltrazuril in broiler chickens

2015 ◽  
Vol 4 (3) ◽  
pp. 310 ◽  
Author(s):  
Ahmed Soliman
Keyword(s):  
Broiler Chickens ◽  
Animal Health ◽  
Tissue Level ◽  
Residence Times ◽  
Once Daily ◽  
Tissue Residue ◽  
Elimination Half ◽  
The Mean ◽  
Mean Residence Times ◽  
Broiler Feed

<p>The pharmacokinetics and tissue residue of toltrazuril (Baycox<sup>®</sup>, Bayer Animal Health) were investigated in broiler chickens after repeated oral administrations of 7 mg/kg b.wt once daily for two consecutive days. Chickens were subjected to clinical diagnosis to ensure that each one is free from any Eimeria was received a standard broiler feed free from any medications. The results revealed that following repeated oral administration; toltrazuril peaked in blood with [C<sub>max</sub>] of 6.56 and 6.70 μg/ml at [T<sub>max</sub>] of 2.56 and 2.52 hours and the elimination half-life [t<sub>1/2β</sub>] of 14.92 and 16.19 hours and the mean residence times (MRT) were 21.33 and 23.14 hours after first and second doses, respectively. The tissue level concentrations were highest in the kidney and decreased in the following order: liver &gt; lung &gt; heart &gt; muscle &gt; skin and fat. No toltrazuril residues were detected in tissues and plasma after 8 days.</p>

Environmental tritium measurements and lumped parameter modelling in the Tafilalet aquifer, south-east Morocco

2007 ◽  
Vol 95 (10) ◽  
Author(s):  
S. Bouhlassa ◽  
B. Ammary ◽  
A. Elyahyaoui
Keyword(s):  
Residence Time ◽  
Subsurface Water ◽  
Residence Times ◽  
Transport Modelling ◽  
Lumped Parameter ◽  
The Mean ◽  
Mean Residence Times ◽  
Environmental Tritium ◽  
Future Work

The paper presents a case study for the application of environmental tritium to assess the mean residence time of water in the Tafilalet aquifer. This aquifer corresponds geologically to a tectonic depression with Quaternary fill. The Tafilalet area depends mainly on agriculture and herding. Groundwater is the main source of water supply for domestic, agriculture, and herding purposes.The data on the distribution of tritium in subsurface water indicate the modern water of the Tafilalet aquifer. The tritium transport modelling indicates that Quaternary alluvial waters are likely to have short mean residence times of a few years (14 to 32 years). The study addresses several difficulties concerning the detailed quantitative interpretations of the results, which must be the focus of future work.

Mean residence times and characteristics of humic substances extracted from a Taiwan soil

2001 ◽  
Vol 81 (3) ◽  
pp. 299-307 ◽  
Author(s):  
M C Wang ◽  
S H Chang
Keyword(s):  
Humic Substances ◽  
Soil Profile ◽  
Fulvic Acids ◽  
Spectroscopic Properties ◽  
Residence Times ◽  
Spin Resonance ◽  
Profile Depth ◽  
Mean Residence Times ◽  
High Degree ◽  
C Nmr

Humic substances are well known for their long-term persistence in soil environments. The relationship between the mean residence times (MRT) and characteristics of humic substances extracted from a soil with highorganic matter (OM) content in Taiwan was investigated. The MRTs of the soil organic matter (SOM) and its humic substances extracted from the soil samples taken from three depths (0–20, 40–60, and 70–150 cm) of a soil profile were determined by 14C-dating procedures. Moreover, the humic substances were subjected to elemental analysis and investigation by electron spin resonance (ESR), Fourier transform infrared (FTIR), and solid-state 13C nuclear magnetic resonance (13C NMR) spectroscopies. The ranges of the MRT of fulvic acids (FA) (MW < 1000), FA (MW > 1000), humic acid (HA) (MW > 1000), and humins (MW > 1000) were 143 ± 110 to 1740 ± 60, 213 ± 120 to 1690 ± 200, 253 ± 60 to 2200 ± 40, and 293 ± 40 to 2173 ± 70 yr, respectively. The higher standard deviations of the means of determined MRTs of FA (MW < 1000) and FAs (MW > 1000) may be due to their lability. Further, the MRTs of the FAs (MW < 1000), FAs (MW > 1000), HAs (MW > 1000), and humins (MW > 1000) increased with increasing soil profile depth, indicating the slow biological and chemical degradations of humic substances in the deeper layers. The elemental composition and spectroscopic properties of FTIR, 13C NMR, and ESR of humic substances did not change significantly with their MRTs. The MRTs in the range observed in this study were apparently long enough to render humic substances a high degree of chemical stability. Key words: Humic substances, mean residence times, ESR, FTIR, 13C NMR, humin

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