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  • Adsorption kinetics  (7)
  • Analytical Chemistry and Spectroscopy  (4)
  • NONMEM  (3)
  • 1
    Electronic Resource
    Electronic Resource
    On the importance of the purity of surfactant solutions in determining their adsorption kinetics (1982)
    Springer
    Colloid & polymer science 260 (1982), S. 1148-1150 
    Details
    ISSN: 1435-1536
    Keywords: Adsorption kinetics ; model of diffusion-kinetic-controlled adsorption ; effect of impurities on adsorption kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract By means of a theoretical experiment it is demonstrated, that a barrier in the adsorption kinetics of a surfactant can be simulated by the presence of surface-active impurities. Hence, the application of models for the diffusion-kinetic-controlled and/or kinetic controlled adsorption presumes the proof of the surface chemical purity of the surfactant solution under investigation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01411238
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  • 2
    Electronic Resource
    Electronic Resource
    Adsorption kinetics measurements of some nonionic surfactants (1986)
    Springer
    Colloid & polymer science 264 (1986), S. 357-361 
    Details
    ISSN: 1435-1536
    Keywords: Adsorption kinetics ; ring and plate method ; nonionic surfactants at solution/ air interface
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Dynamic surface tension values of aqueous surfactant solutions were measured by using the ring and plate method. The mean diffusion coefficients calculated on the basis of the purely diffusion controlled adsorption model vary between 2 · 10−6 to 7 · 10−6 cm2/s for all surfactants studied:n-alkanols,n-alkanoic acids, dimethyl and diethyln-alkyl phosphine oxides. That means the surfactants investigated adsorb with a purely diffusion controlled adsorption mechanism and no barriers excist to hinder sorption processes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01418196
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  • 3
    Electronic Resource
    Electronic Resource
    Determination of population pharmacokinetic parameters for amikacin in neonates using mixed-effect models (1998)
    Springer
    European journal of clinical pharmacology 53 (1998), S. 337-341 
    Details
    ISSN: 1432-1041
    Keywords: Key words Amikacin ; Neonate ; Pharmacokinetics ; NONMEM
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: The population pharmacokinetics of amikacin, in neonates, was investigated using the nonlinear mixed effects model (NONMEM). Methods: One hundred and six steady-state amikacin serum levels were obtained from 53 black neonates with a mean gestational age of 35.1 weeks and mean age at the start of treatment of 3.1 days. A one-compartment model was used to fit the data. Results: The final models for clearance (CL) and volume of distribution (V) were: where WT = birth weight (kg) and P = 1.28 for girls and 1.0 for boys. Inclusion of other fixed effect parameters in the model did not significantly improve the fit of the data. The inter-individual variability for CL and V were 18% and 13%, respectively. Intra-individual variability was 29%. Mean (95% CI) values of CL, V and half-life were 0.048 (0.045, 0.051) l· h−1· kg−1, 0.434 (0.414, 0.453) l· kg−1 and 6.4 (6.2, 6.6) h respectively. Conclusion: Birth weight was an important determinant of both CL and V and, in this data set, gender was also found to influence CL. Mean population pharmacokinetic values were within the range of those previously derived for other neonatal populations using traditional methods.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002280050389
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  • 4
    Electronic Resource
    Electronic Resource
    A model for the determination of carbamazepine clearance in children on mono- and polytherapy (1998)
    Springer
    European journal of clinical pharmacology 54 (1998), S. 359-362 
    Details
    ISSN: 1432-1041
    Keywords: Key words Carbamazepine ; Population pharmacokinetics ; Children ; NONMEM
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: To derive a model describing carbamazepine (CBZ) clearance in children, in terms of individual patient characteristics. Methods: One hundred and eighteen steady-state serum carbamazepine concentration measurements were gathered during normal routine care of 72 compliant out-patients (2.3–16.3 years old). Levels were obtained from patients receiving monotherapy (55%), concomitant valproate (26%), or concomitant inducers (phenytoin, phenobarbitone; 19%). A one-compartment model was used to fit the data with the computer programme Nonlinear Mixed Effects Model (NONMEM). Results: Weight, age and concomitant medication were all important determinants of clearance. The final model for clearance (l · h−1) was: CL = [0.7(WT)0.4] · M, where WT is patient weight (kg) and M is a scaling factor for concomitant medication, with a value of 1 for patients on CBZ monotherapy or concomitant valproate and 1.4 for those receiving concomitant inducers. For the purposes of this analysis, bioavailability (f) was assumed to be complete, i.e., f is thus included in the term CL. Conclusions: CBZ clearance decreased with increasing age. As age and weight were correlated, either variable was a satisfactory predictor. The influence of both the inducers and valproate on CBZ clearance was as expected. This model, which describes clearance in terms of patient-specific details, can be used when predicting the maintenance dose required to achieve a target mean steady-state CBZ concentration in children.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002280050475
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  • 5
    Electronic Resource
    Electronic Resource
    Determination of phenobarbitone population clearance values for South African children (1995)
    Springer
    European journal of clinical pharmacology 48 (1995), S. 381-383 
    Details
    ISSN: 1432-1041
    Keywords: Phenobarbitone ; children ; population pharmacokinetics ; NONMEM ; concomitant medication
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Non-linear Mixed Effects Modelling (NONMEM) was used to estimate phenobarbitone population clearance values for South African children, using 52 serum levels gathered from 32 patients during their routine care. NONMEM was also used to evaluate the influence of fixed effects such as weight, age and concomitant medication. The final model describing phenobarbitone clearance was CL=[Exp(0.0288 Wt−2.53)] M, where CL=clearance (l·h−1), Exp=the base of the natural logarithm, Wt=patient weight (kg) and M=a scaling factor for concomitant medication with a value of 1 for patients on phenobarbitone monotherapy, 0.62 for those receiving concomitant valproate and 0.87 for those patients receiving concomitant carbamazepine or phenytoin. Mean (95% confidence interval) phenobarbitone clearance values were 7.6 ml·h−1·kg−1 (6.2, 9.0 ml·h−1·kg−1) for the monotherapy group, 5.0 ml·h−1·kg−1 (4.0, 6.0 ml·h−1·kg−1) in the presence of concomitant valproate and 6.8 ml·h−1·kg−1 (5.6, 8.0 ml·h−1·kg−1) in the presence of concomitant carbamazepine or phenytoin. These values are similar to those previously reported from both traditional and NONMEM pharmacokinetic studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00194954
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  • 6
    Electronic Resource
    Electronic Resource
    On the application of quantitative models of diffusion-controlled adsorption kinetics at fluid interfaces (1988)
    Springer
    Colloid & polymer science 266 (1988), S. 532-538 
    Details
    ISSN: 1435-1536
    Keywords: Adsorption kinetics ; surfactant transport ; Langmuir isotherm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The model of diffusion-controlled adsorption kinetics can be solved by different mathematical procedures. For the most important case of a Langmuir isotherm, useful solutions are summarized and extended and the ranges of application are given. New approximations are presented which can be applied to most experiments in practice.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01420764
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  • 7
    Electronic Resource
    Electronic Resource
    On the theory of adsorption kinetics of ionic sufactants at fluid interfaces 4. Deceleration of the adsorption rate due to non-equilibrium distribution of adsorbed ions in the diffuse layer (1994)
    Springer
    Colloid & polymer science 272 (1994), S. 548-553 
    Details
    ISSN: 1435-1536
    Keywords: Adsorption kinetics ; ionic surfactants ; non-equilibrium electric double layer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract An approximate analytical solution is obtained for the adsorption kinetics equation derived earlier. On the basis of these relations the importance of the consideration of a non-equilibrium diffuse layer has been shown. To describe the retarded adsorption kinetics the distribution of adsorbed ions in the diffuse layer section of multivalent surfactant ions has been taken into account. The rate of adsorption calculated for a non-ionic surfactant is compared with the adsorption rate for monovalent and bivalent ionic surfactants, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00653220
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  • 8
    Electronic Resource
    Electronic Resource
    On the theory of adsorption kinetics of ionic surfactants at fluid interfaces (1983)
    Springer
    Colloid & polymer science 261 (1983), S. 335-339 
    Details
    ISSN: 1435-1536
    Keywords: Adsorption kinetics ; ionic surfactants ; influence of the electric double layer ; theory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The influence of the electric field caused by an electric double layer (DL) on the adsorption kinetics of charged surfactant molecules at fluid interfaces is described for the case of high surface potentials and a quasi-equilibrium state of the DL. Known relations for the description of the transport of molecules in the diffusion layer and the DL respectively are used.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01413940
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  • 9
    Electronic Resource
    Electronic Resource
    Adsorption kinetics of alkyl phosphine oxides in water/alkane systems with transfer across the interface (1997)
    Springer
    Colloid & polymer science 105 (1997), S. 346-350 
    Details
    ISSN: 1435-1536
    Keywords: Adsorption kinetics ; surfactants ; transfer across ; interface ; interfacial tension ; water/hexane ; n-alkyl dimethyl phosphine oxides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The adsorption kinetics of alkyl phosphine oxides soluble both in water and in alkanes has been experimentally studied by measuring the dynamic interfacial tension. To this aim the pendant drop method was used with an automatic acquisition of the drop shape (ASTRA). The experimental results show that under particular geometrical and initial conditions, the dynamic interfacial tension exhibits a minimum. This nonmonotonic behaviour can be explained by considering the transfer of matter through the surface during the adsorption and the depletion of one phase necessary to establish the partition equilibrium. These data can be interpreted on the basis of a diffusion controlled adsorption model involving two finite phases. Moreover a particular experimental procedure for measuring the partition coefficient has been used based on the equilibrium surface tension measurements and on the evaluation of the adsorption isotherm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01188976
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  • 10
    Electronic Resource
    Electronic Resource
    Adsorption kinetics of surfactants from micellar solutions (1981)
    Springer
    Colloid & polymer science 259 (1981), S. 1124-1128 
    Details
    ISSN: 1435-1536
    Keywords: Adsorption kinetics ; surfactants ; micellar solutions ; theory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Zusammenfassung Es wird ein Modell für die diffusionskontrollierte Adsorption von Tensiden aus mizellaren Lösungen angegeben und numerisch gelöst. Das dabei zugrundegelegte Modell für die Mizellkinetik entspricht einem Bildungs-Auflösungs-Mechanismus. Es wird der Einfluß von Parametern wie Mizellkonzentration, Assoziationsgrad, Geschwindigkeitskonstanten der Mizellkinetik auf die Adsorptionskinetik diskutiert.
    Notes: Summary A model of diffusion controlled adsorption of surfactants from micellar solutions is given and numerically solved. The model used to describe the micelle kinetics corresponds to a formation-dissolution mechanism. Parameters like micelle concentration, aggregation number, rate constant of formation or dissolution of micelles influencing the adsorption process are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01524900
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