Choral singers are among intensive voice users whose excessive vocal effort puts them at risk of developing voice disorders. The aim of the work was to assess voice quality for choral singers in the choir at the Polish-Japanese Academy of Information Technology. This evaluation was carried out using the acoustic parameters from the COVAREP (A Collaborative Voice Analysis Repository For Speech Technologies) repository. A prototype of a mobile application was also prepared to allow the calculation of these parameters.

The study group comprised 6 male and 19 female choir singers. The control group consisted of healthy non-singing individuals, 50 men and 39 women. Auditory perceptual assessment (using the RBH scale) as well as acoustic analysis were used to test the voice quality of all the participants. The voice quality of the female choir singers proved to be normal in comparison with the control group.

The male choir singers were found to have tense voice in comparison with the controls. The parameters which proved most effective for voice evaluation were Peak Slope and Normalized Amplitude Quotient.

The article presents the results of the last stage of work on the impact of changes in the roll pass design on the state of residual stresses in railway rails. The discussed stage includes the summary of industrial experiments of rolling 60E1 rails with a length of 120 meters using a modified pass design of roll grooves. The rolling technology has been deeply modified, ranging from the finishing stand, through the pre-finishing stand, to the semi-finishing stand. The rails in this experiment were cooled using standard cooling technology and then straightened using innovative vertical straightener shaped rollers. Residual stresses were tested using the strain gauge method and the hole-drilling strain gauge method by drilling a hole in the rail axis and at a distance of 14 millimetres from its axis. The resulting tensile stresses in the rail foot were reduced to an average level of less than 43% in relation to the requirements of the EN13674-1 standard.

Bactericidal activity of caprylic acid (CA) and hydrogen peroxide (HP) was investigated in this study in order to design a suitable formulation for use in the food-processing industry. Antibacterial effects of the two chemicals were tested in vitro against the reference strains of Salmonella enterica subsp. enterica serotype Enteritidis CCM 4420, Escherichia coli CCM 3988, Listeria monocytogenes CCM 5578 and Staphylococcus aureus CCM 4223, as well as against the wild bacterial strains obtained from various food commodities (poultry meat, rabbit meat, raw milk sheep cheese ‘Bryndza’) and potable water. First, suspension test was carried out to determine the minimum bactericidal concentrations for individual chemical compounds. While most Gram-negative bacteria tested were effectively inhibited by HP at a 0.5% concentration, the growth of Gram-positive bacterial strains was stopped by a 2% solution. CA showed similar antibacterial effect on all bacterial strains tested except for Staph. aureus showing the same sus- ceptibility as Gram-negative bacteria. The wild strains generally had higher resistance to both chemicals than the reference strains. Combination of HP and CA at concentrations of 0.01%; 0.05% and 0.1% was further tested by the suspension test, carrier test, and carrier test with simul- taneous exposure to UV light. The total bactericidal activity against selected foodborne pathogens was already observed at a concentration of 0.1% and the efficiency was significantly increased by the use of UV radiation. A novel disinfectant based on the combination of HP with CA appears to be a suitable binary formulation for potential use in the food sector.

The paper concerns the problem of treatment of the systematic effect as a part of the coverage interval associated with the measurement result. In this case the known systematic effect is not corrected for but instead is treated as an uncertainty component. This effect is characterized by two components: systematic and random. The systematic component is estimated by the bias and the random component is estimated by the uncertainty associated with the bias. Taking into consideration these two components, a random variable can be created with zero expectation and standard deviation calculated by randomizing the systematic effect. The method of randomization of the systematic effect is based on a flatten-Gaussian distribution. The standard uncertainty, being the basic parameter of the systematic effect, may be calculated with a simple mathematical formula. The presented evaluation of uncertainty is more rational than those with the use of other methods. It is useful in practical metrological applications.