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Compressive stress is found to improve the characteristics of all types of hot hole masers and lasers in p-Ge. Effects of the uniaxial stress of p-Ge crystal on the FIR emission in both E 11 Hand E l H fields are discussed.Mechanisms of the influence of uniaxial stress on the powlation inversion and the stimulated emission of hot holes are revealed.Dynamic heating of the charge carriers in p-Ge in strong electric and magnetic fields (streaming) is known to result in the population inversion and in the stimulated emission at different optical transitions of hot holes in the FIR region (see, for example, [l]). The uniaxial compressive stress splits the top of the valence band at p = 0 A = 4-6meVkbar-', thus affecting the hole dynamics and scattering processes in E, H fields. In the negative cyclotron mass (NCM) maser the effect of the uniaxial stress seems to result directly from the valence band splitting eliminating the band warping and the negative masses at 8 < A/2 << ho, (see figure 1) and diminishing the density

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The importance of concrete as a structural material is undeniable. The key indicator of concrete as a construction material is strength. Creating and solving a concrete strength mathematical model will allow optimizing raw material costs, increasing the financial result of concrete production, and managing the concrete strength at the stage of its production. The authors reviewed existing concrete strength mathematical models. In the considered models, the concrete strength was influenced by various factors – water-cement ratio, C3S hardness, etc. The authors used the kinetic theory of solid destruction as the basis for their mathematical model of concrete strength. The process of destruction of the sample is considered without deformation. Applying the concept of strained and broken bonds, the authors constructed and solved a concrete strength mathematical model. The main parameters of the model are the speed formation coefficient of the stressed bonds and the speed formation coefficient of destroyed bonds. The model allows estimating the time required for sample destruction at a given load. This is a non-trivial conclusion.