Repozytorium Uniwersytetu Śląskiego RE-BUŚ
Not a member yet
23505 research outputs found
Sort by
Crystallization Mechanism and Optical Properties of Antimony-Germanate-Silicate Glass-Ceramic Doped with Europium Ions
No full textGlass-ceramic is semi-novel material with many applications, but it is still problematic
in obtaining fibers. This paper aims to develop a new glass-ceramic material that is a compromise
between crystallization, thermal stability, and optical properties required for optical fiber technology.
This compromise is made possible by an alternative method with a controlled crystallization process
and a suitable choice of the chemical composition of the core material. In this way, the annealing
process is eliminated, and the core material adopts a glass-ceramic character with high transparency
directly in the drawing process. In the experiment, low phonon antimony-germanate-silicate glass
(SGS) doped with Eu3+ ions and different concentrations of P2O5 were fabricated. The glass material
crystallized during the cooling process under conditions similar to the drawing processes'. Thermal
stability (DSC), X-ray photo analysis (XRD), and spectroscopic were measured. Eu3+ ions were used
as spectral probes to determine the effect of P2O5 on the asymmetry ratio for the selected transitions
(5D0 7F1 and 5D0 7F2). From the measurements, it was observed that the material produced
exhibited amorphous or glass-ceramic properties, strongly dependent on the nucleator concentration.
In addition, the conducted study confirmed that europium ions co-form the EuPO4 structure during
the cooling process from 730 ◦ C to room temperature. Moreover, the asymmetry ratio was changed
from over 4 to under 1. The result obtained confirms that the developed material has properties
typical of transparent glass-ceramic while maintaining high thermal stability, which will enable the
fabrication of fibers with the glass-ceramic core
Antistaphylococcal Activities and ADME-Related Properties of Chlorinated Arylcarbamoylnaphthalenylcarbamates
No full textPattern 1-hydroxy-N-(2,4,5-trichlorophenyl)-2-naphthamide and the thirteen original carbamates
derived from it were prepared and characterized. All the compounds were tested against
Staphylococcus aureus ATCC 29213 as a reference and quality control strain and in addition against
three clinical isolates of methicillin-resistant S. aureus (MRSA). Moreover, the compounds were evaluated
against Enterococcus faecalis ATCC 29212, and preliminary in vitro cytotoxicity of the compounds
was assessed using the human monocytic leukemia cell line (THP-1). The lipophilicity of the prepared
compounds was experimentally determined and correlated with biological activity. While pattern
anilide had no antibacterial activity, the prepared carbamates demonstrated high antistaphylococcal
activity comparable to the used standards (ampicillin and ciprofloxacin), which unfortunately were ineffective
against E. feacalis. 2-[(2,4,5-Trichlorophenyl)carba- moyl]naphthalen-1-yl ethylcarbamate (2)
and 2-[(2,4,5-trichlorophenyl)carbamoyl]naphthalen-1-yl butylcarbamate (4) expressed the nanomolar
minimum inhibitory concentrations (MICs 0.018-0.064 gM) against S. aureus and at least two
other MRSA isolates. Microbicidal effects based on the minimum bactericidal concentrations (MBCs)
against all the tested staphylococci were found for nine carbamates, while 2-[(2,4,5-trichlorophenyl)
carbamoyl]naphthalen-1-yl heptylcarbamate (7) and 2-[(2,4,5-trichlorophenyl)carbamoyl]naphthalen-
1-yl (4-phenylbutyl)carbamate (14) demonstrated MBCs in the range of 0.124-0.461 gM. The selectivity
index (SI) for most investigated carbamates was >20 and for some derivatives even >100. The performed
tests did not show an effect on the damage to the bacterial membrane, while the compounds
were able to inhibit the respiratory chain of S. aureus
Przeciw myśleniu modelami. Jaka racjonalność teologii?
No full textTen artykuł jest kontynuacją polemiki z „myśleniem modelami” w teologii, jaka ukazała
się w Studia Bobolanum (2021, 1). Krytyka myślenia modelami została tu pogłębiona,
co pozwoliło ukazać dwa radykalnie odmienne paradygmaty uprawiania teologii,
czyli dwie jej racjonalności. Myślenie modelami jest znakiem i efektem racjonalności
opartej na myśleniu nauki nowożytnej, a przede wszystkim na logice matematycznej.
Tej racjonalności przeciwstawiam paradygmat podmiotowy: teologia powinna być
uprawiana jako myślenie wychodzące od podmiotu i uznające prymat podmiotu nad
tym, co przedmiotowe, obiektywne. Intelektualnym fundamentem takiego myślenia
jest filozofia podmiotu. Dla takiej teologii szczególnie ciekawa jest, jako metoda
myślenia, fenomenologia, a jako metafizyka ‒ myśl Levinasa. Język teologii również
odzwierciedla przyjęty paradygmat. Na koniec pokazuję, że przyjęcie paradygmatu
(przedmiotowego lub podmiotowego) w teologii ma poważne skutki w teologii praktycznej
i w dydaktyce teologii
Pirandello, czyli jak nie dowierzać swojej rzeczywistości
No full textSzkic pragnie przedstawić estetykę Pirandella jako finezyjne dziedzictwo estetyki ruin, której świetnym przedstawicielem we włoskiej tradycji był Giovanni Battista Piranesi. Pisze o tejże estetyce Umberto Eco, że to, co dostrzegamy w pisarstwie włoskiego dramaturga: „zmienia ona radykalnie koncepcję doskonałości formalnej i całkowitości dzieła sztuki”, co więcej – „dopuszcza znajdowanie przyjemności w dziele sztuki mimo tego (a może dzięki temu), że przedstawia ono zniszczenie”. A wszystko sumuje na tej samej stronie cytat z Diderota: „dlaczego piękny szkic urzeka nas bardziej od skończonego obrazu? Bo więcej w nim życia, a mniej formy. Kiedy pojawiają się formy, zanika życie”. Ten sąd francuskiego filozofa mógłby posłużyć jako ważny szlak interpretacyjny dzieła Pirandella.
Instytucja literatury sprawuje władzę nad formą, a więc i nad językiem. Ale jak wynika z rozważań Pirandella, literatura jest instytucją zimną. Litera nie jest w stanie utrzymać ciepła życia, racjonalność nie radzi sobie z „mętami” życia. A ponieważ historia powierza się literze, przechowuje się i przekazuje za jej pośrednictwem, przeto życie zawsze wymknie się z jej jurysdykcji. Dzieło Pirandella to ważny epizod w wielkiej historii zachodniego racjonalizmu, akcentujący to, iż historia to dzieje wysiłków, na ogół niezbyt udanych, do skonstruowania świata wedle zaleceń rozumności
Transforming the Use of Agricultural Premises under Urbanization Pressures : A Story from a Second-Tier Post-Socialist City
No full textDiverse aspects of de-agrarianization, which is manifested by the cessation or significant reduction in agricultural activities, have been clearly visible at the outskirts of large cities in Central Europe in recent decades. The key drivers behind this process include increased pressures to cover peri-urban agricultural land by new developments, inadequate protection of agricultural land, ineffective implementation of urban planning policies, low recognition of the importance of agriculture, and overall changes in people’s dietary habits. Urbanization pressures undoubtedly belong to the factors intensifying overall de-agrarianization, as urban farmers are usually not able to compete with other urban functions. This article focuses on more in-depth understanding of the driving forces behind de-agrarianization processes that are specific to post-socialist cities. As a case study, Brno, a second-tier city in the Czech Republic, was selected. In the first part, the conceptual framework and drivers of de-agrarianization are discussed specifically for the case of large Central European post-socialist cities. In the next part, we explore by means of a set of qualitative interviews the case study of the regeneration of the area of a former Cistercian monastery in Brno that was traditionally used for agricultural purposes, but recently was redeveloped for a university campus. Our findings signal procedural issues connected to the preservation of architectural heritage during the regeneration that frequently end up with only fragments being preserved. We also demonstrate a decline in the use of urban agricultural properties that are hastily transformed into a new urban environment under extremely strong urbanization pressures. We argue that even in economically prosperous cities with highly neoliberal competition between possible urban land uses, agriculture must be considered a relevant and highly important urban function and more protected by planning tools
Unraveling the DNA Methylation in the rDNA Foci in Mutagen-Induced Brachypodium distachyon Micronuclei
No full textMany years have passed since micronuclei were first observed then accepted as an indicator of the effect of mutagens. However, the possible mechanisms of their formation and elimination from the cell are still not fully understood. Various stresses, including mutagens, can alter gene expression through changes in DNA methylation in plants. In this study we demonstrate for the first time DNA methylation in the foci of 5S and 35S rDNA sequences in individual Brachypodium distachyon micronuclei that are induced by mutagenic treatment with maleic acid hydrazide (MH). The impact of MH on global epigenetic modifications in nuclei and micronuclei has been studied in plants before; however, no in situ analyses of DNA methylation in specific DNA sequence sites are known. To address this problem, we used sequential immunodetection of 5-methylcytosine and fluorescence in situ hybridization (FISH) with 5S and 25S rDNA probes on the non-dividing cells of B. distachyon. Such investigations into the presence or absence of DNA methylation within specific DNA sequences are extremely important in plant mutagenesis in the light of altering gene expression
Rola patogenów w kreowaniu różnorodności biologicznej. Wpływ rozkładających się hub na różnorodność gatunkową mikrostawonogów w Karkonoskim Parku Narodowym
No full textBracket fungi are organisms important to forestry, often perceived from the point of view of economic losses they cause, but they also play an important role in shaping biodiversity, e.g. by creating specific microhabitats to which their fruiting bodies belong. The fruiting bodies of this group of fungi are the place of occurrence of invertebrate assemblages specific for them, however, this topic is still poorly researched. The aim of the study was to assess the effect of the degree of decay (DD) of fruiting bodies on the microarthropod communities inhabiting them. The study material (100 fruiting bodies) was collected in the Karkonosze National Park, which areas were affected by a large-scale forest dieback process in the 1980s. 29,228 individuals of microarthropods belonging to 186 species were extracted. Oribatid mites were the most numerously represented group (87 species and 24,472 individuals) and the most numerous species was Carabodes femoralis (20,167 ind.). In addition to the species previously observed also in other substrates, species characteristic only for fruiting bodies of arboreal fungi were also observed (e.g. Hoploseius oblongus). Each DD's fauna differed from one another, in the majority of microarthropod groups there was a tendency for greater number of species and individuals in higher DDs; however, it was not a linear one. The NMDS and cluster analyses indicated that the 3 DD and 4 DD samples are similar to each other, whereas 1 DD and 2 DD samples differed from the samples belonging to the other DDs. Indicator species analysis has indicated species characteristic for each DD, among others Hoploseius oblongus for 1 DD and Zerconopsis remiger for 4 DD. The results encrease the knowledge on the poorly-understood aspekt of ecology and can be a useful source of information for effective protection of forest biodiversity and sustainable forest management
Atomistic origin of nano-silver paracrystalline structure: molecular dynamics and x-ray diffraction studies
No full textClassical molecular dynamics (MD) and x-ray diffraction (XRD) have been used to establish the origin of the paracrystalline structure of silver nanoparticles at the atomic scale. Models based on the face-centred cubic structure have been computer generated and their atomic arrangements have been optimized by the MD with the embedded-atom model (EAM) potential and its modified version (MEAM). The simulation results are compared with the experimental XRD data in reciprocal and real spaces, i.e. the structure factor and the pair distribution function. The applied approach returns the structural models, defined by the Cartesian coordinates of the constituent atoms. It has been found that most of the structural features of Ag nanoparticles are better reproduced by the MEAM. The presence of vacancy defects in the structure of the Ag nanoparticles has been considered and the average concentration of vacancies is estimated to be 3 at.%. The average nearest-neighbour Ag–Ag distances and the coordination numbers are determined and compared with the values predicted for the bulk Ag, demonstrating a different degree of structural disorder on the surface and in the core, compared to the bulk crystalline counterpart. It has been shown that the paracrystalline structure of the Ag nanoparticles has origin in the surface disorder and the disorder generated by the presence of the vacancy defects. Both sources lead to network distortion that propagates proportionally to the square root of the interatomic distances
Soil seed bank responses to edge effects in temperate European forests
No full textAim: The amount of forest edges is increasing globally due to forest fragmentation
and land-use
changes. However, edge effects on the soil seed bank of temperate forests
are still poorly understood. Here, we assessed edge effects at contrasting spatial
scales across Europe and quantified the extent to which edges can preserve the seeds
of forest specialist plants.
Location: Temperate European deciduous forests along a 2,300-km
latitudinal
gradient.
Time period: 2018–2021.
Major taxa studied: Vascular plants.
Methods: Through a greenhouse germination experiment, we studied how edge effects
alter the density, diversity, composition and functionality of forest soil seed
banks in 90 plots along different latitudes, elevations and forest management types.
We also assessed which environmental conditions drive the seed bank responses at the forest edge versus interior and looked at the relationship between the seed bank
and the herb layer species richness.
Results: Overall, 10,108 seedlings of 250 species emerged from the soil seed bank.
Seed density and species richness of generalists (species not only associated with
forests) were higher at edges compared to interiors, with a negative influence of C : N
ratio and litter quality. Conversely, forest specialist species richness did not decline
from the interior to the edge. Also, edges were compositionally, but not functionally,
different from interiors. The correlation between the seed bank and the herb layer
species richness was positive and affected by microclimate.
Main conclusions: Our results underpin how edge effects shape species diversity and
composition of soil seed banks in ancient forests, especially increasing the proportion
of generalist species and thus potentially favouring a shift in community composition.
However, the presence of many forest specialists suggests that soil seed banks still
play a key role in understorey species persistence and could support the resilience of
our fragmented forests
The Effect of Various Poly (N-vinylpyrrolidone) (PVP) Polymers on the Crystallization of Flutamide
No full textIn this study, several experimental techniques were applied to probe thermal properties,
molecular dynamics, crystallization kinetics and intermolecular interactions in binary mixtures
(BMs) composed of flutamide (FL) and various poly(N-vinylpyrrolidone) (PVP) polymers, including
a commercial product and, importantly, samples obtained from high-pressure syntheses, which
differ in microstructure (defined by the tacticity of the macromolecule) from the commercial PVP.
Differential Scanning Calorimetry (DSC) studies revealed a particularly large difference between the
glass transition temperature (Tg) of FL+PVPsynth. mixtures with 10 and 30 wt% of the excipient. In
the case of the FL+PVPcomm. system, this effect was significantly lower. Such unexpected findings
for the former mixtures were strictly connected to the variation of the microstructure of the polymer.
Moreover, combined DSC and dielectric measurements showed that the onset of FL crystallization is
significantly suppressed in the BM composed of the synthesized polymers. Further non-isothermal
DSC investigations carried out on various FL+10 wt% PVP mixtures revealed a slowing down of FL
crystallization in all FL-based systems (the best inhibitor of this process was PVP Mn = 190 kg/mol).
Our research indicated a significant contribution of the microstructure of the polymer on the physical
stability of the pharmaceutical—an issue completely overlooked in the literature