Luxemburg-gorky effect retooled for elastic waves: a mechanism and experimental evidence

A new mechanism is proposed for the linear and amplitude-dependent dissipation due to elastic-wave-crack interaction. We have observed one of its strong manifestations in a direct elastic-wave analog of the Luxemburg-Gorky effect consisting of the cross modulation of radio waves at the dissipative nonlinearity of the ionosphere plasma. The counterpart acoustic mechanism implies, first, a drastic enhancement of the thermoelastic coupling at high-compliance microdefects, and, second, the high stress-sensitivity of the defects leads to a strong stress dependence of the resultant dissipation.     

Comparative Effect of Low-intensity Laser Radiation in Green and Red Spectral Regions on Functional Characteristics of Sturgeon Sperm

A comparative study of the effect of low-intensity laser radiation in green (λ = 532 nm) and red (λ = 632.8 nm) spectral regions at equal average irradiance (3 mW cm⁻²) on functional characteristics of Siberian sturgeon spermatozoa is carried out. Confirmation of the photobiomodulation effect of the radiation is obtained by analyzing spermatozoa motility, percentage of motile spermatozoa and fertilization rate. It is shown that, depending on the energy dose, the laser radiation in red and green spectral regions can have both stimulatory and inhibitory effects on spermatozoa motility. Contrary to popular belief that the short-wavelength radiation has great prospects in reproductive biotechnologies (due to more efficient absorption of radiation by cellular chromophores and increased generation of ROS), convincing evidence of a more pronounced stimulatory effect of radiation in the red spectral region was obtained. For the first time, metal-free porphyrins capable of acting as endogenous photosensitizers generating ROS were detected and identified in animal sperm. Using luminol-dependent chemiluminescence, it is shown that the increased production of ROS capable of exerting an inhibitory effect on biological systems at high concentrations is among the possible reasons for reduction in the stimulatory effect of radiation when moving from red to green spectral region.     

Single machine scheduling with time-dependent linear deterioration and rate-modifying maintenance

We study single machine scheduling problems with linear time-dependent deterioration effects and maintenance activities. Maintenance periods (MPs) are included into the schedule, so that the machine, that gets worse during the processing, can be restored to a better state. We deal with a job-independent version of the deterioration effects, that is, all jobs share a common deterioration rate. However, we introduce a novel extension to such models and allow the deterioration rates to change after every MP. We study several versions of this generalized problem and design a range of polynomial-time solution algorithms that enable the decision-maker to determine possible sequences of jobs and MPs in the schedule, so that the makespan objective can be minimized. We show that all problems reduce to a linear assignment problem with a product matrix and can be solved by methods very similar to those used for solving problems with positional effects.     

Synthesis of indene derivatives via reactions of vinylidenecyclopropanes with the N-acyliminium cations generated from hydroxylactams

A novel route for the synthesis of 1H-indene derivatives via the reactions of vinylidenecyclopropanes (VCPs) with the N-acyliminium cations generated from hydroxylactams is described.     

Study of Self-Diffusion of Silicone MQ Resins in Chloroform Solutions by Pulsed Field-Gradient NMR Spectroscopy

The self-diffusion of silicone MQ copolymers in solutions with chloroform was studied by pulsed field-gradient nuclear magnetic resonance over a wide range of macromolecular concentrations. The highly branched structure of the molecules reveals some characteristic features of the translational mobility. The studies were performed with the initial MQ copolymer as well as with the narrow-dispersed fractions obtained from it. The data indicate the differences in dynamics between fractions. The appearance of the species with different self-diffusivity with increasing of the polymer concentration in solutions was observed. Such behavior was attributed to the formation of aggregates of macromolecules in solution. The results show that the molecular weight influences the diffusion behavior of the MQ resins in solutions. The diffusion of the MQ resins reveals features characteristic for rigid macromolecular structures rather than flexible polymers. Differences in translational dynamics of MQ copolymers, linear flexible polymers and particle-like macromolecules are discussed.