Theoretical analysis of the Rose-Fowler-Vaisberg model

Results of numerical calculations based on the Rose-Fowler-Vaisberg model of radiation-induced conductivity in a case polymer upon long (10⁴ s) irradiation at doses of 5 × 10⁵–10⁷ Gy are reported. Two irradiation modes were considered: (1) preliminary irradiation and irradiation repeated at variable times after the end of the first irradiation and (2) probing the virgin and irradiated polymer with a standard pulse of ionizing radiation. It was shown that the properties of radiation-induced conductivity, such as its overshoot kinetics, a considerable difference between current transients for the initial and the repeated irradiation, extremely long annealing times of dose effects, and the absence of a steady state, are naturally explained in terms of this model (with allowance for the generation of radiation-induced traps as regards the last property). The Rose-Fowler-Vaisberg theory should be considered at present a well-approved semiempirical model of radiation-induced conductivity in polymers.     

Anomalous Diffusion Equations with Multiplicative Acceleration

A generalization of the model of Lévy walks with traps is considered. The main difference between the model under consideration and the already existing models is the introduction of multiplicative particle acceleration at collisions. The introduction of acceleration transfers the consideration of walks to coordinate–momentum phase space, which allows both the spatial distribution of particles and their spectrum to be obtained. The kinetic equations in coordinate–momentum phase space have been derived for the case of walks with two possible states. This system of equations in a special case is shown to be reduced to ordinary Lévy walks. This system of kinetic equations admits of integration over the spatial variable, which transfers the consideration only to momentum space and allows the spectrum to be calculated. An exact solution of the kinetic equations can be obtained in terms of the Laplace–Mellin transform. The inverse transform can be performed only for the asymptotic solutions. The calculated spectra are compared with the results of Monte Carlo simulations, which confirm the validity of the derived asymptotics.     

Analysis of dispersive carrier transport based on numerical solution of multiple-trapping equations

A numerical packet has been developed to solve multiple-trapping equations with an exponential trap distribution without any restrictions on the dispersion parameter, which can be both smaller and greater than unity. Attention has been focused on current transients recorded upon the near-surface, as well as bulk, excitation of the polymer in the small-signal mode. The results have been compared with published data. The program has been used for a critical review of published experimental results obtained by the time-of-flight technique.     

Temperature dependence of the mobility of charge carriers during dispersive transport

The numerical solution of equations in terms of the multiple-trapping model with an exponential energy distribution of traps is used as a basis for the analysis of the temperature dependence of the mobility of charge carriers estimated from the results of time-of-flight experiments for near-surface (classical case) and uniform irradiation of polymer samples in the weak-signal regime.     

Regularities in adsorption of anthocyans by natural clays

Regularities of adsorption by clay of some commercial sorts of anthocyans extracted from plant materials are investigated. The interrelation between sorption ability and structure of sorbates is revealed. Introduction of organic solvent is shown providing a possibility of targeted changing sorption properties of system and sorption purification of anthocyans.     

The effect of composition of the reaction medium on the structural-textural characteristics of mesoporous silicon dioxide

The conditions for the preparation of mesoporous silicon dioxide in water-alkali, alcohol-alkali, water-ammonia, alcohol-ammonia, and acid media were determined and its textural characteristics were studied.     

Failure of immunocompetitive capillary electrophoresis assay to detect disease-specific prion protein in buffy coat from humans and chimpanzees with Creutzfeldt-Jakob disease

The emergence of a new environmentally caused variant of Creutzfeldt-Jakob disease (vCJD), the result of food-born infection by the causative agent of bovine spongiform encephalopathy (BSE), has stimulated research on a practical diagnostic screening test. The immunocompetitive capillary electrophoresis (ICCE) assay has been reported to detect disease-specific, proteinase-resistant prion protein (PrPres) in the blood of scrapie-infected sheep. We have applied this method to blood from CJD-infected chimpanzees and humans. The threshold of detection achieved with our ICCE was 0.6 nM of synthetic peptide corresponding to the prion protein (PrP) C-terminus, and 2 nM of recombinant human PrP at the optimized conditions. However, the test was unable to distinguish between extracts of leucocytes from healthy and CJD-infected chimpanzees, and from healthy human donors and patients affected with various forms of CJD. Thus, the ICCE assay as presently performed is not suitable for use as a screening test in human transmissible spongiform encephalopathies (TSEs).