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Open access

H. Bąkowski, A. Posmyk and J. Krawczyk

Tribological Properties of Rail Steel in Straight Moderately Loaded Sections of Railway Tracks

The paper describes the examination results of tribological properties of three types of steels used and suggested for rails manufacturing. The tests concentrated on loads, sliding and rolling speeds similar to those occurring in real conditions i.e. rolling track operation. Average loaded conditions were assumed and applied at straight railway track sections. Slight track declivity and high/low speeds of locomotive were considered. "Amsler" stand was used for laboratory tests. Three types of steels i.e. two pearlitic steels: WHT - without heat treatment, HT - with heat treatment (with the microstructure of fine pearlite) as well as one bainitic steel suggested for rail production have been tested. The measurements of wear, hardness, friction coefficient as well as structural changes at surface layers of the tested rollers have been performed during the test.

Open access

A. Krawczyk, J. Jaworska-Adamu and K. Rycerz

Abstract

High concentration of glutamate (Glu) is excitotoxic for nervous system structures. This may lead to glial reactivity ie. increased expression of glial fibrillary acidic protein (GFAP) and S100β protein, and also to hypertrophy and proliferation of cells which are determined by the presence of Ki-67 antigen. The aim of the study was to analyse the immunoreactivity of the GFAP, S100β and Ki-67 proteins in astrocytes of hippocampal CA1 region in young rats after administration of monosodium glutamate (MSG) at two doses: 2 g/kg b.w. (I group) and 4 g/kg b.w. (II group). In rats from I and II group morphologically altered astrocytes with the GFAP expression were observed in the SLM of the hippocampal CA1 region. The cells had eccentrically located nuclei and on the opposite site of the nuclei there were single or double, long and weakly branched processes. Moreover, in the SLM the increase of the number of GFAP and S100β immunopositive astrocytes and nuclei with Ki-67 expression, in contrary to control individuals, was observed. These results suggest the increased expression of the proteins in early reactions or hyperplasia which, together with cell hypertrophy, indicate late reactivity of astroglia in response to glutamate noxious effect.

Open access

Maciej Dębski and Adriana Krawczyk

Abstract

Objective: Tourist regions are characterized by a very high complexity and micro-enterprises are the largest group of entities which determine the competitiveness of the destination. However, management of such businesses has a strong specificity. The goal of this paper is to identify the capabilities of managing competitiveness and marketing of this group of entities.

Methodology: Literature review, examining and discussing the current knowledge regarding the competitiveness of family tourist micro-enterprises.

Findings: On the one hand, small companies have significant limitations compared to larger companies. However, the family nature of the company allows for high flexibility of management. Decisions can usually be made faster and easier, which means that they are able to adapt their offer to the expectations of customers faster and better than large entities. Also, an atmosphere of hospitality and friendship can be easily created. What is more, cooperation with other local entities should result in the ability to offer higher value to consumers.

Value Added: Authors, on the bases of literature review have proposed a model that shows relations as an element of building competitiveness of a family tourist micro-enterprises. It appears that these firms have unique opportunities to develop relationships with their customers. Cooperation, quality and communication have been described as key variables responsible for this process, that should result in generating the benefits of re-selecting the services of the company as well as giving them positive recommendations.

Recommendations: In the area of family businesses in tourism, there is still lack of empirical studies. That is why, the issues presented in this work should be subjected to empirical verification. Future research should concentrate on the specificity of managing a tourist family micro-enterprise and on possible sources of competitive advantage of a tourist family micro-enterprise in the eyes of customers. Especially, described model should be empirically verified.

Open access

J. Demuth, M. Hromada, A. Krawczyk, A. Malecha, M. Tobolka and P. Tryjanowski

Abstract

We investigated the occurrence of cranial lesions caused by helminth parasites in the European polecat Mustela putorius in a museum collection in Slovakia. Selected traits of polecat body morphology and condition were studied with respect to the prevalence of the parasites, and number and extent of helminth-caused lesions in crania of 183 adult polecats. The trematode Troglotrema acutum was identified as the parasitic agent (prevalence 62.6 %), with a strong relationship between number of lesions and extent of cranial damage (surface of cranium). Prevalence of infection did not differ significantly between sexes (68.9 % in females, 51.1 % in males). Females with lesions by Troglotrema acutum have significantly greater braincase breadth than uninfected ones. Among males, infected individuals were generally significantly heavier and larger than uninfected individuals. Therefore, contrary to assumptions, it seems that parasites did not influence significantly body measurements of the animals, and differences are probably rather a result of an intra-sample age variation among infected polecats (older individuals are bigger, more probably infected and damage is more pronounced).

Open access

A. Krawczyk and E. Słota

Abstract

Nematode parasites are the major animal health constraint in sheep production on pasture and cause serious economic losses. Because of failure of anthelmintic drenches, a major research effort has been underway to examine alternatives to chemical control. One of them is selecting sheep which are genetically resistant to parasitic nematodes. However, this last is not widely practiced because of the difficulty of measuring parasite resistance which mostly relies on indirect criteria such as number of nematode eggs passed in the sheep faeces (FEC) packed cell volume (PCV) or enhanced number of eosinophils in peripheral blood. Despite the well known host immune reaction it has been impossible to standardize any immunological parameter and use it as an indicator of parasitic infection. The aim of finding some genetic markers associated with resistance/susceptibility to nematodes is to make diagnostic work easier and conduct an earlier selection of desirable genotypes. However, searching for reliable genetic markers is rather difficult due to different sheep’s manifestation of resistance to either the adult or larval stages of the same parasite species and against the same parasitic stage and various manifestations of the immune responses and antigens against parasites. This review summarizes findings reported in the literature relating to genetic markers to gastrointestinal nematodes resistance in sheep.

Open access

Agata Zdyb and Stanisław Krawczyk

Abstract

Natural flavonoids quercetin, morin, fisetin and luteolin were studied as potential photosensitizers for dye-sensitized solar cells (DSSC). Spectroscopic methods were used to investigate the formation of dye/TiO2 nanoparticles assemblies and the development of their absorption spectra. The results show that the flavonoids adsorb well on TiO2 nanoparticles and this process causes the shift of absorption spectra from the near UV into the visible range of solar light. The mode of binding of the dye molecules on TiO2 surface is analyzed by comparison of spectral absorption properties and with the use of structural differences introduced by fisetin and luteolin for discrimination between several possibilities.

Open access

J. Krawczyk, A. Łukaszek-Sołek, T. Śleboda, P. Bała, S. Bednarek and M. Wojtaszek

Strain Induced Recrystallization in Hot Forged Inconel 718 Alloy

Changes in the microstructure of Inconel 718 resulting from hot forging were investigated in this work. Axisymmetrical forging characterized by the areas of different forging reduction ratios was subjected to the analysis. The investigated alloy was forged under various thermomechanical conditions. Two forging modes, differing by the geometry and the temperature of the billet were performed in industrial conditions. It was revealed, that the microstructure of the alloy after forging was in the solutionized condition with different levels of recrystallization determining the differences in the grain size.

Moreover, numerous simulations of the analyzed forging process taking into account variable thermomechanical conditions were performed using QForm 3D v. 5.1 software. The results of the simulations were compared with the results of forging the investigated alloy in industrial conditions. These results showed to be in very good agreement with the experimental observations. The changes in the microstructure of the investigated alloy forging were also compared with the results of the performed simulations. This study allowed determining both the influence of chosen thermomechanical parameters on recrystallization process in hot forged Inconel 718 alloy as well as the possibility of obtaining good quality forgings with uniform microstructure out of this alloy.

Open access

R. Kawiecka, A. Krawczyk, P. Lewińska, K. Pargieła, Stanisław Szombara, A. Tama, K. Adamek and M. Lupa

Abstract

The article presents comprehensive documentation of the situation of post-mining Miedzianka village (former town), which is located in Lower Silesia, in south-western Poland. Due to the long-term expansive mining exploitation since the 14th century, over time Miedzianka was completely destroyed and depopulated, thus nowadays, only a few inhabitants live there. The basis for the conducted research area were changes in land and urban structure that have been occurring for centuries in connection with mining operation of copper and uranium. The authors focused on presenting the changes using archival cartographic documentation, land surveying measurements and 3D modelling. That data allowed to determine on the ground specific sites related to mining operations, discover old urban buildings, performing their 3D models and finding places potentially threatened by continuous and discontinuous deformations. The combination of all the data allowed to present the full situation that occurred in Miedzianka.

Open access

K. Rycerz, A. Krawczyk, J. Jaworska-Adamu, M. Gołyński, K. Lutnicki and I. Balicki

Abstract

Habanero pepper fruits contain capsaicin (CAP) characterised by a spicy taste. Astrocytes express vanilloid receptor (TRPV1), which interacts with cannabinoids including CAP. Only a few studies revealed that CAP leads to alterations of the arcuate nucleus (ARC) structures. The aim of this study was to analyse the GFAP (GFAP-IR) and S100β (S100β-IR) immunoreactive astrocytes of ARC in adult rats after intragastric administration of habanero pepper fruits. Adult, Wistar rats received a peanut oil – control group (C) – and oil suspension of habanero pepper fruits at a dose of 0.08 g dm/kg b.w. for 7 days – E1 group – and 28 days – E2 group. After euthanasia, the brains were embedded in paraffin blocks using a routine histological technique. Frontal slices of ARC were immunohistochemically stained for GFAP and S100β using specific antibodies in the peroxidase-antiperoxidase method. Astrocytes of ARC were morphologically and morphometrically analysed under a light microscope. The results of the study did not reveal statistically significant changes in the density of GFAP-IR cells in E1 and E2 groups of rats in comparison with group C. A statistically significant increase in the density of S100β-IR astrocytes was observed in the E1 group and a decrease in the E2 group. Astrocytes with expression of both studied proteins were characterised by morphological alterations in ARC in the E2 group. The obtained results suggest an influence of CAP contained in habanero pepper fruits on the reactivity of astroglia, which may have an impact on the astrocyte-neuron interactions in order to maintain a proper activity of nervous cells in ARC.

Open access

Wójcik P, Krawczyk P, Chorostowska-Wynimko J, Reszka K, Duk K, Muszczyńska-Bernhard B, Pankowski J, Wojas-Krawczyk K, Czyżewicz G, Ramlau R, Skoczek M, Grenda A, Orłowski T, Grodzki T, Piwowar M, Roszkowski-Śliż K and Milanowski J