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Earlier, a number of publications presented the results of an experimental study of the free oscillations of the piezometric level of groundwater (pressure in a liquid) in wells with natural frequencies. In this case, the oscillations were initiated by a pulsed action on the aquifer through disturbing wells. The same publications proposed a theoretical interpretation of the established phenomenon. However, a critical analysis of these theoretical constructions showed their incorrectness. Accordingly, a consistent physical and mathematical model of groundwater relaxation filtration is proposed in this work, which provides a theoretical basis for the description and interpretation of the free oscillations of the piezometric level in a disturbing well with natural frequencies. Thus, the proposed physical and mathematical model made it possible to conclude that it is impossible to cause resonance during the initiation of free oscillations of the piezometric groundwater level. An analysis of the experimental data based on the model showed that the implementation of methodological developments based on the theory of relaxation filtration is possible and expedient only on fundamentally different, in comparison with existing, technical and methodological approaches to the experimental study of wave propagation in aquifers.

The results of the thermal pressure bonding of printed circuit board materials are presented. Results have shown a disposition of prepreg leakage at inner printed circuit boards layers. To estimate how the placement of cavities affects the amount of leaked prepreg a pattern of several milled squares was formed at a top layer of the circuit board. This estimation may help designers of certain technology-based boards (cavity milled) to place PCB cavities at optimal positions and provide data about critical bounds, at which positioning of circuit board cavities may be rejectable or at least less desirable.

Dihalogens readily interact with trimethylamine-N-oxide under ambient conditions. Accordingly, herein, stable 1 : 1 adducts were obtained in the case of iodine chloride and iodine bromide. The crystal and molecular structure of the trimethylamine-N-oxide–iodine chloride adduct was solved. Furthermore, the geometry and electronic structure of the trimethylamine-N-oxide–dihalogen complexes were studied computationally. Only molecular ensembles were found in the global minimum for the 1 : 1 stoichiometry. The O⋯X–Y halogen bond is the main factor for the thermodynamic stability of these complexes. Arguments for electrostatic interactions as the driving force for this noncovalent interaction were discussed. Also, the equilibrium structures are additionally stabilised by weak C–H⋯X hydrogen bonds. Consequently, formally monodentate ligands are bound in a polycentric manner.

Samples of Chernobyl fuel debris, including massive corium and &ldquo, lava&rdquo, were collected inside the Chernobyl &ldquo, Sarcophagus&rdquo, or &ldquo, Shelter&rdquo, in 1990, transported to Leningrad (St. Petersburg) and stored under laboratory conditions for many years. In 2011 aged samples were visually re-examined and it was confirmed that most of them remained intact, although some evidence of self-destruction and chemical alteration were clearly observed. Selected samples of corium and &ldquo, were affected by static leaching at temperatures of 25, 90 and 150 &deg, C in distilled water. A normalized Pu mass loss (NLPu) from corium samples after 140 days was noted to be 0.5 g/m2 at 25 &deg, C and 1.1 g/m2 at 90 &deg, C. For &ldquo, samples NLPu was 2.2&ndash, 2.3 g/m2 at 90 &deg, C for 140 days. The formation of secondary uranyl phases on the surface of corium and &ldquo, samples altered at 150 &deg, C was confirmed. The results obtained are considered as an important basis for the simulation of fuel debris aging at Fukushima Daiichi nuclear power plant (NPP).