AGH University of Science and Technology in Kraków
Recent publications
In this paper, the impact of water activity regarding storage environment on mechanical and water properties is presented, as well as the structural and morphological features of triple-layered films. Furcellaran (FUR), chitosan (CHIT) and carp skin gelatin hydrolysates (HGEL) were used for the production of the film. The films were made using a casting method, in which three successive stages were applied. First stage: preparation (pouring onto the mould) of 1st layer – FUR + HGEL, second: 2nd layer preparation (pouring onto 1st layer) – FUR, and third: 3rd layer (pouring onto 1st layer) – CHIT + HGEL. The second and third steps began after gelation of the previously poured layer. The drying process of the film was carried out for 24 h under a fume hood at room temperature. The mechanical properties of control sample was: tensile strength The control sample has tensile strength 7.76 ± 0.35 MPa, elongation at break – 3.69 ± 0.33%, maximum breaking load – 15.86 ± 0.58 N. Water properties of control sample – water absorption a solubility were 25.80 ± 1.14% and 52.91 ± 1.31%, respectively. Reducing the water content in the film increased its tensile strength (from 7.76 ± 0.35 MPa for the control film to 14.36 ± 0.07 MPa) and elongation at break (from 3.69 ± 0.34% for the control film to 8.74 ± 0.69%). Reducing water content in the film also decreased its ability to absorb water, which is crucial in the case of biodegradable films due to their hydrophilic nature. The multimolecular sorption of the films was described using the BET model. Structural and morphological changes observed on the basis of surface and cross-section photographs of the films confirm the negative impact of high water activity on the film and its mechanical parameters.
This paper presents an experimental and numerical investigation of the performance of a sorbent polymer composite (SPC) material used for removing mercury from the flue gases in a full-scale industrial installation. The investigated material is an attractive alternative to activated carbon, which is commonly used for this purpose. While the application of the SPC is characterized by high capital expenditures, this technology offers not only very low operating expenditures but also high efficiency. This study investigates the SPC’s mercury reduction capabilities concerning the most important flow parameters such as gas velocity, temperature, humidity, and mercury concentration. Small scale laboratory experiment was used to tune the kinetic data of the mercury adsorption. The resulting sub-model has been built into the CFD simulations validated against measurements at an industrial installation. The results showed that the most important parameters affecting the mercury reduction efficiency were the gas velocity and mercury content in the sorbent material. Numerical simulation proved that the material absorbs mercury within the entire reasonable operating temperature and humidity ranges, regardless of mercury speciation.
The Oligocene Menilite Beds are considered the most important source rock for hydrocarbon accumulation in the Polish Carpathian region, whereas the Cretaceous Lgota Beds have been regarded as an additional potential source rock. Understanding their petrophysical and geochemical properties is essential for evaluating the hydrocarbon potential of these beds. This paper presents mineral and organic porosity characterization and focuses on factors responsible for the development of organic pores as a reflection of the depositional and diagenetic processes. Mudstones were evaluated as potential source and reservoir rocks, describing their diagenetic and thermal history and examining their effective porosity and permeability. The results show that the Lgota Beds mudstone in the Huczwice quarry is thermally mature (late oil/early gas window, Tmax 460–470 °C), containing type III kerogen and TOC between 0.68 wt% and 4.2 wt%, in contrast to the Menilite Beds mudstone (Monasterzec outcrop), which is thermally immature (Tmax<426 °C), containing type II kerogen and TOC content from 1.24 wt% to 8.7 wt%. The geochemical properties show that the Lgota mudstone is currently an ineffective source rock, whereas the Menilite mudstone can be a potential source rock. SEM-identified pores include mineral pores, organic pores and microfractures. Organic porosity is observable both in immature oil-prone type II kerogen and highly mature gas-prone type III kerogen. The amount of pores in organic matter increases with maturity, and no relation between TOC and organic porosity development has been observed. Palynofacies analysis showed that the Menilite and Lgota mudstones are dominated by amorphous organic matter, and that the Lgota mudstone also contains opaque woody material. MICP measurements indicate high (up to 15%) effective porosity values for the Menilite Beds and up to 8% for the Lgota Beds, with very low permeability values (<0.1 mD) in both cases. Isotherms obtained from nitrogen adsorption are type IV for the Lgota Beds and type II for the Menilite Beds, while the BET surface areas are around 13 m²/g and 3 m²/g, respectively. The Lgota Beds demonstrate advanced diagenetic processes such as compaction, cementation, dissolution, replacement, and transformation, which contributed to the significant reduction in porosity, while the Menilite Beds represent an early stage of burial with the prevailing impact of compaction and thus less destruction of original pores. Finally, the Menilite Beds from the Monasterzec outcrop do not demonstrate sufficient conditions for shale-oil/-gas source rock due to the lack of proper thermal maturity. Such criterion is fulfilled by the Lgota Beds in the Huczwice quarry, but due to very low hydrocarbon potential, the Lgota mudstone is an ineffective source rock. However, given the other petrophysical and geochemical properties, the analysed formations may constitute a basis for further research on the occurrence of unconventional reservoirs in the entire Carpathian region.
Optically stimulated luminescence (OSL) and radiocarbon (¹⁴C) techniques were employed to investigate the absolute ages of alluvial sediments in Podhale in the West Carpathians, southern Poland. This is an approach to (i) testing the credibility of the above dating methods by their reciprocal age control and (ii) further implications to regional geochronology and to dating campaigns of alluvial sequences elsewhere. Nine geological sections comprised of mineral and organic material were selected for the study. Our age determinations range from 26.9 to 2.27 ka, and are in good geochronological order. OSL age estimates show good agreement with independent ages from radiocarbon dating. However, in three alluvial successions the discrepancy between the resulting ages is considerable. We attribute the difference to the partial bleaching, and organic material redeposition. We also report on an age reversal of sediments in a single geological section. This might have been resulted from the alluviation-erosion scheme of meandering rivers over a millennial time-scale, i.e. the dominance of channel migration, point bar deposition (lateral accretion), and crosswise erosion. Finally, new geochronological data are provided abolishing sediment age assumptions based on uncertain chronostratigraphical approaches.
A modified wet chemical method involving different chelating acids was applied to prepare a series of lead-free K0.5Na0.5NbO3 (KNN) piezoelectric ceramics. The microstructural, dielectric, spectral and ferroelectric properties of the obtained ceramics were investigated as part of a comparative study. Thermal characteristics specific to a phase transition were detected via high-temperature HT-XRD, FT-IR and EIS. The obtained sinters were dense and consisted of micro-sized grains. Sinters obtained from powders prepared from oxalic acid with the addition of tartaric acid exhibited lower dielectric constants and lower coercive field values than those synthesized using oxalic acid only (332 vs 399 and 10 vs 9.5 kV⋅cm− 1, respectively) measured at room temperature. The KNN ceramics exhibited high conductivity (>10− 3 S/cm at 600 ◦C), dielectric loss (~200 at 1 kHz) and high remnant polarization (~310− 3 μC/cm2).
This paper focuses on the study of multiplicity and concentration phenomena of positive solutions for the singularly perturbed double phase problem with nonlocal Choquard reaction{−ϵpΔpu−ϵqΔqu+V(x)(|u|p−2u+|u|q−2u)=ϵμ−N(1|x|μ⁎G(u))g(u),inRN,u∈W1,p(RN)∩W1,q(RN),u>0,inRN, where 1<p<q<N, 0<μ<N, ϵ is a small positive parameter and V is the absorption potential. Combining variational and topological arguments from Nehari manifold analysis and Ljusternik-Schnirelmann category theory, we prove the existence of positive ground state solutions that concentrate around global minimum points of the potential V. In the second part of this paper, we establish the relationship between the number of positive solutions and the topology of the set where V attains its global minimum. The main results included in this paper complement several recent contributions to the study of concentration phenomena.
The work aimed at the development of benign solid base catalysts as alternatives for presently used noxious liquid bases. Talc, possessing intrinsic basic properties, was chosen as a particularly attractive and cost-effective precursor. Activation of talc by grinding in a planetary mill followed by treatment with 2 M NaOH was employed as means for basicity enhancement. Such protocol enabled profound modification of talc structure, otherwise resistant to treatment with a basic solution. Deep changes, not addressed in the literature reports so far, took place in the course of combined mechanical and alkali treatment. The amorphized ground talc transformed to the magnesium silicate hydrate (MSH) phase and brucite. Treatment with NaOH led to significant enhancement of surface basicity with respect to the parent materials. The effect was particularly spectacular for alkali-treated, strongly ground talc samples, containing the MSH component. The materials were tested in a base-catalyzed reaction of aldol condensation of acetone. The trend of catalytic activity followed closely the order of surface basicity, which pointed to the key role of MSH as a catalytically active phase in the modified talc solids. Joint mechanical and alkali activation of talc proved to be a simple, yet promising way of developing solid base materials for catalytic applications.
Vision based techniques are successfully applied in for Structural Health Monitoring (SHM). Between them one can distinguish thermography, video-based methods and hyperspectral imaging method. Hyperspectral Imaging (HSI) is a method of obtaining an array of two-dimensional images over a wide range of wavelengths in the electromagnetic spectrum. HSI has found its applications in the fields of geographic remote sensing, food quality inspection, vegetation monitoring and medicine. One of the areas in which HSI usage is still developing is Structural Health Monitoring. There is a big potential of the HSI application because during hyperspectral imaging we can detect changes in physical and chemical properties of materials under the test. The aim of the study was to develop a technique for damage detection in glass fibre reinforced polymer composites, which is relatively difficult to achieve with other optical methods. The hyperspectral images for healthy and damaged composite samples are compared. For detection of damages, two approaches were investigated; a target detection algorithm using spectral data as the detection criterion, and an algorithm based on cointegration analysis. The strengths and weaknesses of both approaches are compared, and their applicability for SHM is assessed.
Damage detection often requires selecting a reference case to which examined instance is compared. This step is important as environmental and operational conditions should correspond in both cases. Commonly, selecting a reference case for damage detection in SHM is performed manually. As this approach is not effective, we introduce the Optimal Baseline Selection method based on analysis of frequency maps of examined structure. The operating object is recorded with the use of a high-speed camera. Vibrations are analyzed using the optical flow technique. The mean frequencies of motion in selected bands are calculated for each pixel. Frequency maps are obtained independently for vertical and horizontal directions of motion, and they are further processed separately. The analyzed frequency map is compared to the maps in a reference set to find the most similar one. This is basically achieved by computing differences between histograms of maps and further calculating statistical measures. Finally, the results obtained for individual directions of motion are combined. The method is demonstrated by an example of a compressor operating under different pressures and damages.
The Younger Dryas (YD) glaciation in the Tatra Mountains developed anew after the glacier-free conditions prevailing during the Bølling–Allerød interstadial. A dry continental climate and relatively warm summers hampered glacier expansion even in the highest cirques (1700–2400 m a.s.l.), while enhanced seasonality and strong winter cooling promoted widespread periglacial processes and rock glacier formation. In consequence, the record of the YD marginal glaciation is represented by an apron-type landsystem with a common moraine–rock glacier continuum located very close (200–600 m) to the highest and most sheltered cirque headwalls in the High and Western Tatras. Several moraines yield consistent dates between 12.5 and 10.9 ka. Exposure ages indicate prolonged stabilisation of YD rock glaciers until the Early Holocene (mean age 11.1 ± 0.9 ka, no later than 10.4 ± 0.7 ka). The YD landforms—moraines and relict rock glaciers—represent the final stage of the Tatra Mountains deglaciation.
Catalysts can be successfully prepared by a simple electrochemical process. Their surface composition distinguishes catalytic activity toward hydrogen and oxygen evolution reactions. In this work, uniform Co-Ni cones were synthesized using the one-step method from an electrolyte containing a crystal modifier. Electrodeposited layers were oxidized and/or reduced in the furnace at 100°C. Freshly electrodeposited coating was stored in air atmosphere for seven days. This results in an oxide layer forming on the surface of the catalyst. Changes in the surface composition, confirmed by the XPS method, strongly influenced the wettability, catalytic performance, and size of evolved hydrogen bubbles. The conical Co-Ni surface oxidized in a controlled way possesses the best catalytic activity towards hydrogen and oxygen evolution. Conversely, the spontaneously formed oxide layer decreases the catalytic performance in mentioned reactions compared with the fresh sample. The proper storage of synthesized samples is essential due to their desired catalytic applications. Proposed controlled oxidation can be an accessible way to increase nanomaterials catalytic performance.
During the final part of the Oldest Dryas cold stadial (~15 ka), the glaciers in the Tatra Mountains were already confined to sheltered areas below high cirque walls and likely disappeared completely responding to Bølling–Allerød Interstadial (B-A) warming. In the High Tatras ice-moulded bedrocks or moraine boulders located in the direct neighbourhood of Younger Dryas (YD) moraines or rock glacier fronts above 2100 m a.s.l. were ice-free already at 14.8–14.2 ka and there is no evidence for moraines left by glaciers during the B-A retreat. In the lower elevated cirques in the Western Tatras, the stabilisation of debris-covered glaciers and rock glaciers was prolonged until the B-A Interstadial (13–14 ka) or even to the YD – Holocene transition (11.9 ka).
The post-Last Glacial Maximum (LGM) deglaciation of the Tatra Mountains (~18–15 ka BP) left a sequence of multiple moraine and rock glaciers in the landscape, which marks the transition between valley to cirque glaciation, when c.90% of glacier length was reduced after full glacial conditions. The earliest glacier readvance occurred likely 18–17 ka BP and the latest one just before the Bølling–Allerød (B-A) Interstadial at c.15 ka BP when the largest cirque glaciers achieved only 0.5–1.5 km in length. During deglaciation overdeepening basins located in lower glacial cirques (~1400–1700 m a.s.l.) in the High Tatras were for the first time ice-free and the oldest lacustrine deposits started to accumulate since the final part of Oldest Dryas. The post-LGM deglaciation was strongly affected by a high rate of debris supply to the glacial systems, leading to a complex assemblage of landforms from moraines and debris-covered glaciers to rock glaciers.
The management and treatment of infectious bacterial diseases in wound healing have both become significant research areas in the biomedical field. While current treatments show limitations related to toxicity and exposure time, nanotechnology has become a potential alternative to overcome such challenges. The application of different nanomaterials, with a wide range of elemental compositions, morphologies, and features, has become an essential tool in managing wound healing infections. This book chapter shows an updated view of the newest trends in the control and treatment of bacterial proliferation in the wound bed by utilizing various metal- and nonmetal-based nanostructures.
As already indicated in Chapter 2, Nanomaterials to aid wound healing and infection control, various types of metallic- and nonmetallic nanomaterials can be used to aid the wound healing process and to keep bacterial infections in check. While serving as powerful tools on their own, various types of nanomaterials can unravel their true potential by being embedded inside a variety of scaffolds and coatings, differing both in chemistry and morphologies. Being embedded inside the material or by covering its surface, NMs alter its physicochemical properties and serve as a means for localized controlled release of various bioactive compounds. By employing such strategies, one can obtain highly functional materials, having great potential to enter clinical applications. This chapter is aimed to summarize the current advances in the field of nanocomposite wound dressings, scaffolds, and coatings. These are used as efficient tools to improve the wound healing efficiency as well as inhibit and/or eradicate microbial infections.
We present the spontaneous growth of self-assembled epitaxial nanostructures of BiFeO3 (BFO) obtained by Pulsed Laser Deposition. The BFO phase architectures of squares, stripes and pyramids were grown on (0 0 1), (1 1 0) and (1 1 1) SrTiO3 (STO) substrates, respectively. The morphology of the BFO nanostructures was determined by Scanning Electron Microscopy and Atomic Force Microscopy revealing their vertical alignment and self-assembled feature on the surface of the entire substrate. Structural analysis was made along in-plane and out-of-plane directions employing X-ray Diffraction. We determined the growth routes of BFO nanostructures and established a relationship between their morphology and structural properties. Such self-ordered crystalline nanostructures could be used as a tailored platform for the deposition of the ferromagnetic phase, thus providing an alternative method for the fabrication of BFO-based multiferroic vertically aligned nanocomposites.
The set of six fluorophosphate glasses were obtained to measure the effect of composition on their thermal and luminescence properties. It was found that the phosphate network can accept much more lithium fluoride as compared to silica and borate glasses. The differential thermal analysis study shows a significant increase of thermal stability and decrease of the crystallization with higher content of lithium fluoride. Simultaneously, a gradual increase in the intensity of thermoluminescence was observed as well as linearity of the thermoluminescence response. We correlated the observed effects with the structural changes based on fourier-transform infrared spectroscopy and magic angle spinning nuclear magnetic resonance analysis.
In this work, Tea Tree Oil (TTO)/chitosan coatings of different TTO concentrations were electrophoretically deposited (EPD) on Zr-2.5Nb alloy substrates. The properties of solutions and EPD kinetics of TTO/chitosan coatings and pure chitosan coatings used as a reference material were analysed. The incorporation of TTO into chitosan solutions changed their zeta potential and conductivity, as well as influencing the EPD kinetics. The microstructure of the coatings consisted of TTO droplets embedded into the chitosan matrix. The addition of TTO resulted in the formation of new hydrogen bonds between chitosan and the TTO main components. Both pure chitosan and TTO/chitosan coatings deposited from solutions containing up to 10 mL/L TTO had excellent adhesion to the rough substrates. The mechanical interlocking was indicated as the main adhesion mechanism of coatings. However, chemical bonding was not excluded. The coatings exhibited a hydrophobic character and showed about 50% lower SFE with a very low value of the polar component compared to substrates. The obtained results on EPD and the characterisation of microstructure, structure and selected properties show that chitosan coatings containing TTO are promising as antimicrobial coatings for metallic biomaterial substrates. However, the antimicrobial properties and cytotoxicity of coatings should be further investigated.
Anthropogenic eutrophication is one of the consequences of human activities observed from the beginning of urbanization processes and is now a widespread problem around the globe. Mitigation of eutrophication directly corresponds to the achievement of at least three main Sustainable Development Goals. Due to the complexity of eutrophication mechanisms, there are still many issues with managing this process and its consequences, that complicate the achievement of the above-mentioned objectives. So far, there is no universal definition of eutrophication and there is no unified methodological approach to surface water trophic status assessment. In connection with the above, a need arises for the development of scientifically and economically justified methods of reliable trophic state assessment, useful for solving application and engineering tasks. This paper presents a new approach to trophic state assessment based on the innovative universal trophic index (UTI), which can be used for fresh, brackish and saltwater bodies. The proposed UTI index was developed and verified using an extensive database of the Baltic Sea monitoring data for over 100 years. The elaborated method is a reliable tool for the assessment of water trophic status, which also allows for the development of predictive mathematical models as the basis for effective eutrophication management. In addition, the method is simple to use and enables the trophic state assessment at low cost, time and effort. The above-mentioned features make the proposed indicator meet the requirements set for modern ecological indicators and determine the advantage of the proposed methodological approach over other currently used methods.
The paper presents the results of heat demand forecasting during the off-season (summertime and transitional period) in a real district heating system. The hourly heat demand in the analyzed system ranges from 16 to 28 MW, depending on the month and hour of the day. Short-term prediction of the heat demand in the day-ahead horizon is needed for effective operation of production units in the Cogeneration Heat and Power Plant (CHP). The method of an hourly heat load predictions using a data-driven model is presented. The algorithm is based on the Generalized Additive Model with hour of the day, day of the week and day of the year as predictors. A way of increasing the accuracy of forecasts using the autoregressive model for residuals of the model was discussed. The influence of the training dataset size on the model error was also examined. The several versions of the model were evaluated by comparing forecasted results with real values during the district heating system's operation from June to the end of August. For the most accurate one, Root Mean Square and Mean Average Percentage Error were 0.84 MW and 3.3 %, respectively.
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8,461 members
Krzysztof Kluza
  • Department of Applied Computer Science
Jacek Maria Banaś
  • Department Of Chemistry and Corrosion of Metals
Aneta Fraczek-Szczypta
  • Department of Biomaterials and Composites
Jaroslaw Kozlak
  • Department of Computer Science; Faculty of Computer Science, Electronics and Telecommunications
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