Thermoacoustic converters are devices for direct conversion of acoustic energy into thermal energy in the form of temperature difference, or vice versa – for converting thermal energy into an acoustic wave. In the first case, the device is called a thermoacoustic heat pump, in the second – thermoacoustic engine. Thermoacoustic devices can use (or produce) a standing or travelling acoustic wave. This paper describes the construction and properties of a single-stage thermoacoustic engine with a travelling wave. This kind of engine works using the Stirling cycle. It uses gas as a working medium and does not contain any moving parts. The main component of the engine is a regenerator equipped with two heat exchangers. Most commonly, a porous material or a set of metal grids is used as a regenerator. An acoustic wave is created as a result of the temperature difference between a cold and a hot heat exchanger. The influence of working gas, and such parameters as static pressure and temperature at heat exchanger on the thermoacoustic properties of the engine, primarily its efficiency, was investigated. The achieved efficiency was up to 1.4% for air as the working medium, which coincides with the values obtained in other laboratories. The efficiency for argon as working gas is equal to 0.9%.

Research in termoacoustics began with the observation of the heat transfer between gas and solids. Using this interaction the intense sound wave could be applied to create engines and heat pumps. The most important part of thermoacoustic devices is a regenerator, where press of conversion of sound energy into thermal or vice versa takes place. In a heat pump the acoustic wave produces the temperature difference at the two ends of the regenerator. The aim of the paper is to find the influence of the material used for the construction of a regenerator on the properties of a thermoacoustic heat pump. Modern technologies allow us to create new materials with physical properties necessary to increase the temperature gradient on the heat exchangers. The aim of this paper is to create a regenerator which strongly improves the efficiency of the heat pump.

The model concept, as presented in this paper, is an original solution created by the author, and can be used as a proposal to build an innovative mechanism to increase the effectiveness of programming and implementation of the development policy, and improve the quality of functioning of a building research institute. The development management system included in this model is a set of actions targeting at the effective use of human and tangible resources, undertaken in a coordinated manner and leading to the achievement of previously established objectives. The market activity of building research institutes is directly or indirectly involved in construction projects, which translates into market mechanisms, such as innovation and competitiveness. In addition, it indicates the participation of a building research institute in the engineering of construction projects as a key to entrepreneurship and implementations.

The author analyses the history of scientific and public discourses growing around the phenom-enon of Głuchoniemcy (Deaf‑Germans) in Poland. In the literature, this term refers to the des-cendants of the German‑speaking colonists who settled in the Polish‑Ruthenian border in the mid‑fourteenth century. The history of interest in this phenomenon from the eighteenth to the twentieth century reflects the cultural changes and social tensions over time. These descendants of the German‑speaking colonists living in the Carpathian Foothills were mentioned for the first time in the eighteenth and beginning of the nineteenth century as a regional phenomenon of cultural diversity. In the era of Romanticism, when the importance of national identity in Europe grew, so‑called Deaf Germans were portrayed as fully assimilated Polish settlers with only relics refer-ring to German culture. At the end of the nineteenth century, after the publication of Józef Szujski, they became the subject of a political debate and were placed in the context of peasant history. Finally, the socio‑political situation of the interwar period led to the term “Głuchoniemcy” being removed from scientific and public discourses for many decades. After World War II, the absence of the topic became permanent, still directly related to the Polish‑German antagonism that set the directions of scientific interests of ethnographers and historians in Poland. The article tries to answer the question about the course of these changes in the perception of Deaf Germans by looking for external causes as well as those resulting from the nature of the subject of interest.

The systematic position of Sorbus population occurring in the Pieniny Mts. is controversial. To verify its taxonomic status we studied the ITS sequence of closely related species of the S. aria group: Sorbus sp. from the Pieniny Mts., S. aria from the Tatra Mts., S. graeca from the Balkans, and other well-distinguished native Polish Sorbus species (S. aria, S. aucuparia, S. intermedia and S. torminalis). As a reference we examined Sorbus populations closest to the Pieniny Mts. where S. graeca was reported to occur, in Slovakia. The results indicate that the Sorbus plants found in the Pieniny Mts. differ genetically from those in the Tatra Mts. but are identical to those collected from the Vihorlat Mts. in Slovakia and are closely related to S. graeca from the Balkans

According to a fuel flexibility, fluidized bed boilers are considered as appropriate for biomass combustion as cofiring. But the burning of fuels such as forest and agricultural biomass raises a number of operational problems. Most important of these problems are bed agglomeration and deposition. Deposition appears when biomass contains significant amounts of alkali elements, such as sodium and potassium. The purpose of the work is to select a fuel additive to overcome these operational problems. Investigations were conducted in two stages at a pilot scale 0.1 MWth laboratory circulating fluidized bed reactor. As the fuel, the mixture of biomass contained forest residues, sunflower husks, straw and wood pellets from mixed woods was selected. In the first stage biomass was burnt without any additives, while in the second one the fuel was enriched with some additive. The additive (liquid mixture of chemicals) was added to the fuel in amounts of 1 dm3 per 5-10 Mg of fuel. The following operational parameters were examined: temperature profiles along the height of the circulating fluidised bed column, pressure profiles, emissions. After the tests, the laboratory reactor was inspected inside. Its results enables expression of the following conclusions: there was no agglomeration during fuel additive testing, and the deposition was reduced as well. Moreover, the parts (heating surfaces, separator) of the laboratory reactor were coated with a protective layer. The layer covered microcracks and protected the parts from deposition for a long period after the operation.

The paper presents results of hearing loss measurements provided for 81 young people (from 16 to 25 years old). The main aim of the work was to find the influence of headphones of the types used (closed, semi-open, open and in-ear) on the hearing losses. The first part of the research was to answer questions about the influence of: time of listening, loudness of music, other noise exposures as well as the type of the headphones used. It turned out that all factors mentioned above influence thresholds of hearing but the found dependencies are not explicit. The greatest hearing losses were observed for people who work as sound reinforcement engineers and, moreover, no influence of the headphone types was found for them. It turned out that the use of in-ear headphones causes the greatest hearing losses for some subjects (thresholds shifted up to about 20 dB HL at 4 kHz). The daily time of a listening also affected the hearing thresholds. It was found that for users of in-ear and close headphones, an average time of musical exposure of three hours causes the hearing loss of 10-15 dB HL at higher frequencies. The use of open as well as semi-open headphones has no influence on the hearing damage. Thus it would be stated that these kinds are safety in use. Almost 15% of the investigated young people have their thresholds shifted up at higher frequencies, particularly at 4 kHz, which means that they have the first symptoms of a permanent hearing damage.

Analytical transmission electron microscopy has been applied to characterize the microstructure, phase and chemical composition of the Ag–Al wear track throughout its thickness down to the atomic level. Microscopy findings have been correlated with Ag–Al film tribological properties to understand the effect of the hexagonal solid solution phase on the tribological properties of this film. Ag–25Al (at.%) films have been produced by simultaneous magnetron sputtering of components in Ar atmosphere under 1 mTorr pressure and subjected to pin-on-disc tribological tests. It has been shown that hcp phase with (001) planes aligned parallel to the film surface dominates both in as-deposited and in tribofilm areas of the Ag–Al alloy film. Possible mechanisms of reduced friction in easily oxidized Ag–Al system are discussed and the mechanism based on readily shearing basal planes of the hcp phase is considered as the most probable one.

Therefore, the aim of the present study was to evaluate the possible effect of bilberry fruit (Vaccinium myrtillus L.) supplement in a daily diet on the cognitive behaviour of the rats and the expression of paravalbumin (PV) in populations of hippocampal neurons. It has been postulated that the antioxidants present in bilberry fruit may act as neuroprotective factors playing also a significant role as memory enhancements. Forty Wistar rats with a similar average body weight (460 ± 0.4 g) were divided into four groups (n=10 per group). The control group received standard feed (210 g/week), whereas animals of experimental groups received standard feed supplemented with bilberry (per os) at consumed doses of 2 g (group I), 5 g (group II), and 10 g/kg b.w./ /day (group III). After three months of feeding with bilberry, the modified elevated plus-maze test (mEPM) was performed. After 32 weeks of feeding, brains were collected and PV-immunoreactive (ir) neurons were immunohistochemically visualized. In the modified elevated plus-maze test, transfer latency examined 2 h and 24 h after the acquisition session was significantly shorter (p<0.05) in the group II in comparison with the control group. In CA1 and CA2/CA3 hippocampal fields as well as dentate gyrus of all experimental groups, a significant (p<0.05) decrease in number of PV-ir neurons were found. In relation to the control group, the mean subpopulation of PV-ir neurons found in groups II and III were significantly reduced. The subpopulations of PV-ir neurons found in DG of all experimental groups were significantly reduced in comparison to the control. In conclusion the in the present paper we demonstrated a relationship between the diet rich in a bilberry fruit and process of memory as well as numbers of calcium- binding protein-expressing hippocampal neurons. Our results may be source of basic knowledge for further research aiming at neuroprotective role of the bilberry fruit.