Electrophysical Parameters of Nanofilled Polymer Composites Based on Polyethylene

The features of the dependence of the dielectric constant and the specific volume resistance of the composite "80 wt. % SKI-3 + 20 % wt. % LDPE" from the content of nanosized filler particles - aluminum and black carbon. The use of modern methods for studying macroscopic properties and electron microscopy made it possible to study the structure and morphology of the supramolecular formations of the composite. Models and possible physical mechanisms leading to extreme changes in εʹ and ρV at low concentrations of nanoparticles are presented.

Impact of Low Volume Velocity-Controlled vs. Repetition to Failure Resistance Training Session on Measures of Explosive Performance in a Team of Adolescents Basketball Players

This study examined the short-term effects (post 6 h and 24 h) of two equated (70% of 1 repetition maximum (1-RM)) low volume resistance exercise protocols: (i) velocity-controlled (VC) and (ii) repetition to failure (RTF) on upper and lower body performance in competitive adolescent male basketball players. Following a randomized, counterbalanced design, ten participants (age: 16 ± 0.5 years) completed either VC or RTF separated by 72 h. VC consisted of 4 sets of 5 explosive repetitions (≥90% of the maximum velocity). RTF involved 2 sets of 10-RM (with no velocity control). Measurements of 20-m sprint, countermovement jump (CMJ) and medicine ball toss (MBT) were collected before (baseline), post 6 h and 24 h after either VC or RTF. Increases of CMJ post 6 h (VC, +6.7%; RTF, +2.4%) and MBT post 24 h (VC, +4.6%; RTF, +4.2%) were observed after both VC and RTF. Only VC potentiated CMJ after 24 h (+2.0 ± 2.3%). No other changes or differences between protocols were observed. Performing a low volume exercise protocol, either VC or RTF, induced similar potentiation effects on the vertical jump (post 6 h) and medicine ball toss (post 24 h) in adolescent basketball players. Only the VC protocol was still effective to potentiate CMJ performance after 24 h.

The Study of the Electrical Conductivity of Apples and Grapes as an Object of Electrical Processing

Experimental studies of the electrical conductivity of whole berries, peels, and pulp of apples and grapes were carried out according to the methods that the measurement voltage should not exceed the threshold and the measurement time should be minimal, and mechanical damage to the cells during contact with the electrodes was not allowed. To study the electrical conductivity (electrical resistance) of apples, grapes, and their constituent elements, a device is developed that represents a three–electrode system. The study of the specific volume resistance of the pulp of apple and grape. Development of a methodology for a three–electrode system to determine the electrical conductivity of the pulp and skin of fruits and grapes. Three–electrode system showed sufficient accuracy for apple and grape the electrical conductivity. The volumetric resistance of the skin was much greater than the pulp. The tissue resistance of fruits and grapes with an increase in the frequency of the measuring current decreases exponentially.