We discuss the properties of the nonlinear diffusion equation for the case of diffusion in excited systems. The diffusion coefficient is directly proportional to the concentration of impurities and depends on the time in a special way. For the description of the excited systems, we used a special temperature function, which defined the time dependent diffusion coefficient and the Boltzmann's distribution of the excited vacancies or impurity atoms in solids. This model was used for approximation of very fast diffusion of metastable vacancies irradiated by soft X-rays in an excited Si crystal.

A numerical method based on the finite-element methodis developed to study active photonic bandgap materials (PBG) offinite size. After validating our method, we focus on metallicPBGs including diodes. These structures are characterized in thefar-field and the near-field, and the influence of diode statesand material finiteness is examined.

The contraction of a stressed rectangular plate-like sample has been investigated considering the mechanical stability of its two lateral free surfaces with respect to localized perturbation.The energy variation of the platehas been calculated to determine the condition of development of symmetric and non-symmetric wavelet fluctuations of the two lateral free surfaces when a constant and homogeneous stress is applied to the plate. The contraction has been then studied when a source of non-homogeneous strain is embedded into the plate.

Bunched and multi-circularly wrapped carbon nanotubes (CNT) are observed to grow on alloy substrates based on iron group metals and copper by a microwave enhanced hot-filament method with a dilute gas of ammonia at a proper RF self-bias. The grown size of CNTs embodied in the grain sizes of conducting bulk alloy catalysts such as Cu-Ni, Cu-Fe, Cu-Co, and Cu-Ni-Fe-Co are controlled by a precursor time of hydrogen plasma etching. Species with different structural features and homogenization of CNTs samples are produced crucially attributed to various reactant gases and self-bias induced by the radio frequency field.

We report a new method of fluorescence lifetime imaging that uses the ultra-fast opticaltemporal gating properties of parametric image amplification. Images with different lifetimes inthe picosecond range are resolved with reliable and reproducible results.

Composites consisting of epoxidized natural rubber (ENR) and organically modified montmorillonite (OMON) in the ratio of 70:30 by weight percent have been synthesized. X-ray diffraction (XRD) measurements were made to estimate the basal plane spacing between the layered structures of the montmorillonite (MON) before and after it was organically modified and also for the composite. The increment in basal spacing of 1.758 nm indicated that intercalation of ENR-50 chains occurred in the silicate layers with the ammonium ion being attached to the layers after the modification. TSC measurements indicated that the intercalation resulted in a suppression of the $\alpha $  peak of the ENR around -25 °C which is also referred to as the T g of the material. Two new and broader peaks around 30 °C and 73 °C appeared in the composite. The suppression of the peak may be interpreted as a result of the increasing rigidity due to the three-dimensional network of physical links formed.

The aim of this paper is the modeling of a dielectric barrier discharge at atmospheric pressure, in the Townsend regime. This model is based on an equivalent electrical circuit. It takes into account the main physical phenomena of the discharge. This model allows to have a general view of the process and to study the influence of the power supply on the discharge. It is also an interesting tool for the power supply design and the process optimization.

This paper is devoted to atactic polystyrene (aPS) thin films treatment under DC pulsed discharge in nitrogen. The experiments were performed using a symmetrical plane-to-plane of electrodes configuration in order to improve the treatment homogeneity and also to compare the treatment efficiency when the aPS is on the cathode or on the anode. During these experiments, the pressure and the electrical conditions were maintained unchanged. The experimental results were compared for the two positions of samples, when the gap length and the afterglow duration time were varied. It appears that the treatment depends on the sample position and an interpretation is proposed. The physical conditions and the reaction processes in the plasma bulk and on the aPS surface were analysed in order to understand their influence on the surface treatment. The importance of metastables is pointed out and it is deduced that these long-life excited states are firstly produced near the anode and fill the gap following the evolution and distribution of the electron current density.

A tight control of acidity is needed for performing oxidation–reduction reactions of organic compounds dissolved in liquid media, since the relevant reactions often involve the occurrence of protons; the matching kinetics are therefore acidity dependent. This feature holds for plasma treatments of aqueous wastes which are intended to abate the concentration in organic pollutants. Exposure of aqueous solutions to a gliding arc plasma in humid air induces acid and oxidising reactions in the condensed phase. Acid effect results from the occurrence of NO species formed in the plasma and leads to the formation in water of nitrous and nitric acids, which are responsible for a steep pH fall. Using selected buffers allows accurate controlling of the acidity, which is necessary for most of the plasma-chemical or plasma-biochemical reactions.