摘要:

Mathematical models in tracer kinetics are usually based on ordinary differential equations which correspond to a system of kinetically homogeneous compartments (standard compartments). A generalization is possible by the admission of inhomogeneities in the behaviour of the elements belonging to a compartment. The important special case of the age-dependence of elimination rates is treated in its deterministic version. It leads to partial differential equations (i.e., systems with distributed coefficients) with the “age” or the “residence time” of an element of the compartment as a variable additional to “time”. The basic equations for one generalized compartment and for systems of such compartments are given together with their general solutions.

ISSN:0021-1915    

DOI:10.1080/10256019108622521

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The general theory of inhomogeneous compartments with age-dependent elimination rates given in part I in a deterministic frame by sets of partial differential equations is illustrated by examples. Mathematically, it turns out that models consisting of partial differential equations include ordinary, delayed and integro-differential equations, a general fact which is treated here in the context of linear tracer kinetics. The examples include standard compartments as a degenerate case, systems of standard compartments (compartment blocks), models resulting in special residence time distributions, models with pipes, and systems with heterogeneous particles.

ISSN:0021-1915    

DOI:10.1080/10256019108622522

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

ISSN:0021-1915    

DOI:10.1080/10256019108622523

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

If nonlinear biological processes are investigated by means of tracer experiments they can be modelled with linear kinetic equations (compartment equations) as long as the total system is in a stationary state. But if nonstationary behaviour is included considerations on the kinetics of the individual processes are necessary. Within the range of biological and agricultural investigations especially first order reactions (constant fraction processes), zero order reactions (constant amount processes) and saturation reactions (Michaelis-Menten-kinetics) are to be taken into account. A rigorous treatment of data based on system theory can be preceded by a graphic-algebraic procedure which may be more or less uncertain in its results but which can easily be handled.

ISSN:0021-1915    

DOI:10.1080/10256019108622524

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The leaching of microconstituents from granular solid wastes is often studied by column experiments. The underlying assumption is that the flow is of the one-compartment or “backmix” type. The influence of small deviations from this ideal situation on the outcome of the leaching experiment depends slightly on the specific mass-transfer function of the trace involved. The deviation itself may be measured by a simple separate radiotracer experiment.

ISSN:0021-1915    

DOI:10.1080/10256019108622525

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Gamma irradiation effects on the electric conductivity behaviour and IR absorption spectra of some thiazole and haloacetato complexes were investigated. A comparison is made between the rate and activation energies of the thermal annealing of electrical properties of pure and γ-irradiated samples. A mechanism is suggested to explain the observed decrease in the intensity of metal-oxygen bond in the IR spectra of the complexes as a result of γ-irradiation.

ISSN:0021-1915    

DOI:10.1080/10256019108622526

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The infrared spectra of poly(ethylene terephthalate) γ-irradiated in presence of organic solvents were recorded over the spectral region 200–300 cm−1. The analysis of these spectra showed that the combined effect of solvent and γ-irradiation results in appearance of two strong bands at 1550 and 1630 cm−1, increase in the intensities of the gauche bands at 1450 and 1370 cm−1and decrease in the intensity of the trans-band at 1340 cm−1. The aromatic ring C=C stretching band at 1410 cm−1was also affected. The profound spectral changes were observed only in samples irradiated in presence of solvents and were not observed in samples treated with solvents or only irradiated in atmosphere of air, these spectral changes were attributed to the changes in the intermolecular of intramolecular forces as a result of penetration of solvent molecules in the polymer and the ionizing effect of γ-iffadiation. It was found that the extent of the intensity variations depends on the nature of the solvent.

ISSN:0021-1915    

DOI:10.1080/10256019108622527

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Cotton linters is irradiated by Co-60 source with different doses (5 … 52 Mrad). The effect of γ-irradiation on the grafting of cotton linters with methylmethacrylate monomer (MMA) is clarified, crystallinity index (CrI) of irradiated samples decreases by increasing the radiation dose. A new hand appeared at 1715 cm−1(C=O) after irradiation. On the other hand, band intensities of some groups at 1600 cm−1(RCOO) are increased or decreased, e.g. OH at 3350 cm−1by irradiation.

ISSN:0021-1915    

DOI:10.1080/10256019108622528

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Direct radiometric measurements of the vapor concentration of H2S in equilibrium with aqueous diethanolamine absorbing solution were made using35S-labeled H2S. A thin-window Geiger-Müller tube viewed the gas phase only, while the absorbing solution was held in another part of the reaction flask. The equilibrium data were measured at H2S partial pressures below 0.01 mm Hg; the agreement with published results obtained by chemical analysis was good. The radiometric results were obtained very rapidly; a test run with seven data points took about two hours to complete. The results were applied to processes for reducing H2S concentrations in petroleum refinery fuel gases needed to meet tightening air pollution requirements.

ISSN:0021-1915    

DOI:10.1080/10256019108622529

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Ion mobilities of silver, cobalt, zinc, gadolinium and europium and their complexonates with NTA, EDTA and DTPA are determined. It is shown that– contrary to the published data the ion mobility of complexonates does not depend on the mobility of the central cation;– complexonates with equal charges show similar mobilities, the deviation being not more than 15% of the average value;– a tendency for the ion mobility to decrease with increasing molecular weight of the complexonate is observed.

ISSN:0021-1915    

DOI:10.1080/10256019108622530

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor