Wroclaw University of Science and Technology
  • Wrocław, dolnoslaskie, Poland
Recent publications
The growing demand for sustainable and clean energy sources provides the incentive for the development of alternative fuels. Simultaneously, the development of gas turbine technologies with flexible fuel supply systems enables the use of alternative non-fossil fuels that can play key roles in contributing to global efforts in meeting emissions targets. This paper presents the current state of knowledge on the production and potential use of pentanol (C5 alcohol) in diesel engines and gas turbines. The combustion performance of a GTM-140 jet engine supplied by mixtures of pentanol with aviation kerosene is then evaluated and the results are compared with those of kerosene mixtures with other biofuels – propanol (C3 alcohol)) and butanol (C4 alcohol)). All the investigated liquid biofuel alternatives showed potential for reducing regulated emissions such as NOX (on average by 40%) and CO (on average by 25%) for C5 alcohol. The increase in the proportion of pentanol in the blends has the effect of reducing the temperature downstream of the combustion chamber on average by 5.8% for Turbine Inlet Temperature (TIT) and 6.1% for Exhaust Gas Temperature (EGT). The jet engine fuel efficiency expressed as thrust specific fuel consumption (TSFC) for all tested biofuels decreased on average by 40% for C5 alcohol. The use of alternative fuels such as bio-alcohols offers real opportunities for cleaner and more environmentally friendly gas turbine operation in aviation and power generation.
To make prognosis one needs to build a model based on historical data. In the paper we propose a framework for modelling of long-term non-homogeneous data with non-Gaussian properties. These specific properties have been identified in real datasets describing the degradation process of the machine. The framework covers deterministic and random components separation, modelling of heavy-tailed, time-varying properties of random part as well as identification of possible autodependence hidden in the random sequence and identification of distribution for a random part. Due to non-linear trends, time-dependent scale (equivalent to the variance for Gaussian distributed data) and non-Gaussian characteristics present in the data, the final formula of the model is complex, its identification is challenging and requires specific, suitable to heavy-tailed processes, statistical methods. The paper provides two kind of novelties — first of all, it uses real data from condition monitoring systems and our findings may be novel and surprising to predictive maintenance community, secondly — processing such specific data opens new areas for general data modelling and highlight novel research directions.
Low-cost walnut shell-based carbons with high microporosity were prepared by simple one-step carbonization with chemical activation using KOH, exhibiting the promising potential to be a very good CO2 and H2 adsorbent. The physicochemical properties of the obtained carbons were characterized by N2 and CO2 adsorption isotherms, X-ray powder diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and elemental analysis. The activated carbon AC-800 was characterized by a highly developed specific surface area of 1868 cm²/g and a high micropore content of 0.94 cm³/g. It highly exhibited CO2 uptake in 1 bar was up to 9.54, 5.17, 4.33 mmol/g for 0, 25 and 40 °C, respectively. In addition, the H2 storage capacity was 3.15 mmol/g at 40 bars. Significantly, confirmed an exceptionally high dependency of CO2 and H2 uptake vs micropores structure of activated carbon. AC-800 also shows good selectivity for CO2/N2 and fast adsorption kinetics that be easily regenerated with superior cyclic stability after multiple cycles The experimental isotherm data of activated carbon produced from walnut shells were analyzed using Langmuir, Freundlich, Temkin, Sips, and Toth isotherm equations. The fitting details showed that the multitemperature Toth equation is a powerful tool to mathematically represent CO2 and H2 isotherms on activated carbon. The easy way of preparation and high capture abilities endow this kind of activated carbon attractive as a promising adsorbent for CO2 and H2 storage.
In the current situation of a serious raw material crisis related to the disruption of supply chains, the bioeconomy is of particular significance. Rising prices and the problem with the availability of natural gas have made N fertilizers production very expensive. It is expected that due to natural gas shortages, conventional production of nitrogen fertilizers by chemical synthesis will be hindered in the coming season. An important alternative and an opportunity to solve the problems of fertilizer nitrogen availability are biological wastewater treatment plants, which can be treated as a renewable biological nitrogen mines. Sewage sludge (including activated sludge) contains up to 6–8% DM. N. Considering the quantity of sewage sludge generated in wastewater treatment plants, it can become an important raw material for the sustainable production of organic-mineral fertilizers from renewable resources available locally, with a low carbon footprint. Furthermore, the sewage sludge management method should take nitrogen retention into account and should not allow the emission of greenhouse gases containing nitrogen. This article analyzes the technological solutions of nitrogen recovery for fertilization purposes from biological wastewater treatment plants in the context of a new and difficult resource situation. Conventional and new nitrogen recovery methods were analyzed from the perspective of the current legal situation. An attempt was made to evaluate the possibility of implementing the assumptions of the circular economy through the recovery of renewable nitrogen resources from municipal wastewater treatment plants.
The problem of reconstruction and quantitative characterization of the microstructure of random composites, as a fundamental problem of material sciences, has been a subject of a considerable amount of literature. Thus far, previous studies used for the reconstruction either statistical microstructure descriptors or the overall property of real material. This paper makes a major contribution to research on reconstruction by formulating a procedure to recover the microstructure that produces the same effective thermal conductivity as the real composite material. In particular, our goal is to find a binary representation of ‘replacement’ microstructure that, being a two-phase statistically isotropic medium, produces minimal disagreement with the experimental data. Such a binary microstructure is invariant with respect to the conductivity of fluid occupying the porous space. Thus, in some sense, the paper is an extension of the concept proposed by Łydżba et al. (2018), who showed, in the framework of analytical homogenization, that any isotropic microstructure can be represented by randomly oriented spheroids of certain distribution over the aspect ratios. The efficiency of our methodology was illustrated by examples including Wiener and Hashin-Shtrikman bounds as well as the microstructure created by the system of non-overlapping disks. Finally, we use our algorithm to construct the ‘replacement’ microstructure for the real porous medium, i.e., medium sand. The main advantage of the digital representation of ‘replacement’ microstructure over the analytical one, is that it can be further used in computational modeling as well as in 3D printing applications.
This chapter is a condensed survey of postimmobilization strategies applied in order to improve the stability and catalytic performance of enzymes before their practical utilization as industrial biocatalysts in continuous or batch-repeated processes. Each procedure is discussed in terms of (i) the active agents used, (ii) the mechanism of created interactions, (iii) the effect on the obtained catalyst preparation, and (iv) particular examples of applied enzymes. The postimmobilization strategies are described separately for enzymes immobilized on/in insoluble carriers and fixed in membrane bioreactors, in order to be clear in the presentation of these data.
The aim of this review is to show the possibilities of food production during space travel and to demonstrate the potential of technological solutions that can play a significant role in achieving the goal of colonizing other planets. The paper briefly outlines the conditions of space flight and the associated possible threats that may occur. It is assumed that the basic problem is cosmic radiation, which not only can significantly affect the health of astronauts, but also prevent potential cultivation of plants or animal breeding on board a spacecraft. The solution to this problem proposed here is a shield which provides protection against collisions with high kinetic energy particles, while reducing the speed of corpuscular radiation. Particular attention is given to various biotechnological and bioengineering methods that could be used for food production on board a spacecraft. Technological development in the field of bioprinting or genetic modification of organisms may play a key role in the success of long-distance technological missions. Moreover, organisms such as algae, fungi and insects are indicated as a potential source of energy for future colonizers. In sum, the review covers both the field of engineering and biotechnology, as well as the possibility of checking these technological methods in the test flights.
The article presents the cross-sectional results of analyzes of authentic conducted disturbances introduced into public power networks by various types of receivers installed at end users. The foundation for the research was a set of 260 identified cases of Power Line Communication (PLC) transmission disturbances based on the Open Smart Grid Protocol (OSGP) technology, which were recorded in the urban network of the distribution system operator covering over 400,000 smart meters. The paper presents a quantitative assessment of the share of receivers that most often cause problems with transmission efficiency. Moreover, a qualitative assessment of the detected disturbance cases was carried out in terms of conditions relating to the structure of the power grid and real transmission levels and disturbance levels. The authors made a pioneering analysis in the so-called "communication path" where the PLC communication disturbance was identified, i.e. from the installation point of the PLC concentrator to the metering point where the energy meter, with which the connection was lost, was installed.
Salivary gland (SG) dysfunction impairs the life quality of many patients, such as patients with radiation therapy for head and neck cancer and patients with Sjögren’s syndrome. Multiple SG engineering strategies have been considered for SG regeneration, repair, or whole organ replacement. An in-depth understanding of the development and differentiation of epithelial stem and progenitor cells niche during SG branching morphogenesis and signaling pathways involved in cell–cell communication constitute a prerequisite to the development of suitable bioengineering solutions. This review summarizes the essential bioengineering features to be considered to fabricate an engineered functional SG model using various cell types, biomaterials, active agents, and matrix fabrication methods. Furthermore, recent innovative and promising approaches to engineering SG models are described. Finally, this review discusses the different challenges and future perspectives in SG bioengineering.
The specific physico-chemical properties of chitosan (Ch), a biopolymer isolated from chitin, and its impact on the stability of colloidal dispersity have focused the interest of science and industry. However, in some cases chitosan alone is not enough to provide high stability to dispersions, making it necessary to add surfactant to the chitosan/oxide system, leading to superior stabilizing properties due to the association of polymer and surfactant molecules to form complexes that can modify the ability of bare chitosan for adsorbing on colloidal materials. This study explores the interactions between chitosan and alumina in the presence of three different anionic surfactants: the hydrocarbon SDS (sodium dodecyl sulfate), the fluorocarbon FS-91 (Capstone® FS-91), and the silicone A-Si (Silphos A-100). Different analytical methods evidenced chitosan adsorption on the alumina surface, forming hybrid organic-inorganic materials. This process can be enhanced by adding surfactant, with SDS leading to a strong increase of chitosan adsorption. Elemental mapping and scanning electron microscope imaging have provided a confirmation of the co-adsorption of polymer and surfactant on the alumina surface. The latter emerges as a very important finding because the results have shown that small quantities of surfactant (as low as 0.002% v/v) can strongly influence the adsorption and stability of multicomponent colloidal systems. This allows decreasing the chitosan amount required for the enhancement of the colloidal stability in relation to dispersions without added surfactants, providing the basis for reducing the production costs of colloidal dispersion, which opens new opportunities to chemical industry.
Proteases are enzymes that hydrolyze peptide bonds in proteins and peptides; thus, they control virtually all biological processes. Our understanding of protease function has advanced considerably from nonselective digestive enzymes to highly specialized molecular scissors that orchestrate complex signaling networks through a limited proteolysis. The catalytic activity of proteases is tightly regulated at several levels, ranging from gene expression through trafficking and maturation to posttranslational modifications. However, when this delicate balance is disturbed, many diseases develop, including cancer, inflammatory disorders, diabetes, and neurodegenerative diseases. This new understanding of the role of proteases in pathologic physiology indicates that these enzymes represent excellent molecular targets for the development of therapeutic inhibitors, as well as for the design of chemical probes to visualize their redundant activity. Recently, numerous platform technologies have been developed to identify and optimize protease substrates and inhibitors, which were further used as lead structures for the development of chemical probes and therapeutic drugs. Due to this considerable success, the clinical potential of proteases in therapeutics and diagnostics is rapidly growing and is still not completely explored. Therefore, small molecules that can selectively target aberrant protease activity are emerging in diseases cells. In this review, we describe modern trends in the design of protease drugs as well as small molecule activity-based probes to visualize selected proteases in clinical settings.
Providing room comfort quickly by using less energy in cooling systems is important both in terms of efficiency and environment. In this study, independent temperature/humidity control strategies are designed for precooled desiccant based evaporative cooling system to provide room comfort quickly with less energy. Therefore, the speed controls of the system's actuators become important depending on the room, cooler and atmosphere conditions. The mathematical models are obtained to determine the relation between voltages of actuators and the variations in the room's temperature and humidity. After that, new control strategies are developed based on Proportional and Fuzzy+Proportional techniques and the control performance is increased by adding extra modes to the operation of the actuators. The effects of the control techniques on the cooling performance and energy consumption were investigated for different cases. It has been observed that the room temperature and relative humidity reach the set values in a short time for both techniques and are successfully kept at these values under the disturbances. By using Fuzzy+Proportional controller, the robustness of the cooler increases due to more precisely adjustment of controller's parameter depending the system conditions. Both control strategies provide more than 20% energy savings compared to the traditional ON/OFF control.
In this article, a novel, pilot-scale gasification technology is closely described from the technological and design points of view. The construction of the fuel bed within the reactor is circular, operating according to the sliding bed principle, equipped with a tangential oxidiser intake. The technology combines principles of cross-draft and updraft gasification reactor type in an autothermal regime. In the model process with softwood pellets (spruce wood) as source fuel, the LHV of the producer gas reached 4.3 MJ·m⁻³, with the overall conversion ratio reaching 80.3%. These results were obtained in a 709 ± 10 °C environment with the fuel feed rate equal to exactly 30 kg·h⁻¹ while the flow rate of the oxidising media was 17 ± 1 m³∙h⁻¹. The gas quality in terms of its content is a major factor to be considered. The purity of the producer gas is crucial for most final-use technologies. Thus, the question of polluting agents and undesired substances is analysed and discussed in this article. The custom-made cleaning track of hereby described scientific technology can operate with 99.9% particulate matter removal efficiency, while tar compounds within the producer gas are kept as low as 9.7 g·m⁻³. This article summarises a detailed description of a specific pilot-scale gasification unit where results of an experimental analysis are depicted along with real-time values and detailed schematic descriptions and illustrations, providing a base for comparison with conventional technology designs.
The past decade has witnessed the rise of low-dimensional materials, such as graphene, transition metal dichalcogenides, black phosphorus, organic–inorganic hybrid perovskites and MXenes. They have received tremendous attention due to their peculiar properties, as compared to their bulk phase. These unique properties have ushered in a paradigm shift in many applied fields and technologies including, but not limited to optoelectronics, catalysis, biomedical research and quantum information sciences. The fundamental processes determining the performance of devices, utilizing the low-dimensional materials, are photogeneration of charge carriers and carrier transport. A detailed understanding of these processes is therefore indispensable to the design and optimization of advanced high-performance low-dimensional materials-based devices for broadband photodetection, high-speed modulation, high-efficiency solar energy harvesting, and energy storage, among others. Herein, we critically review recent advances in studies of photoinduced carrier dynamics in low-dimensional semiconductors and semimetals. Transient carrier generation, trapping and recombination dynamics can be controlled by temperature, charge transfer in hybrid structures, electrical and magnetic field, and stress. Revealing the mechanisms and strategies of their tuning should help design and optimize multifunctional materials to enable high-performance devices. In this review, we do not focus exclusively on the photoinduced species (excitons and charge carriers), but also discuss possible strategies to adjust their properties and their impact on device characteristics. To conclude, we summarize current status, describe existing challenges, and provide a subjective opinion on future opportunities to advance this exciting field. We hope that this review will be appealing to a broad materials physics audience and will be helpful in exploring new physics and discovering theory guided novel materials with robust performance.
The paper discusses the applicability of the novel Dual Beam Laser Sintering (DBLS) method for processing of poly(lactic acid)/hydroxyapatite (PLA/HAp) composite powders. The composite microspheres were prepared using the solid-in-oil-in-water (S/O/W) emulsification technique. The three-dimensional structures made of composite microspheres with different filler content – 5 % and 10 % by weight of HAp were processed using DLBS that uses a new method of preheating the powder bed. The obtained results were compared to the case of pure PLA presented in our previous work. The quality of the powders was determined using Dry Laser Diffraction (DLS), X-Ray Computed Tomography (XCT), Revolution Powder Analysis (RPA) and Differential Scanning Calorimetry (DSC). The melt flow rate and the thermal conductivity of the microspheres were also determined. Conducted research shows that the morphology of the particle depends heavily on the HAp content which ultimately influences the powder flowability properties. Moreover, the properties of samples manufactured using DBLS were evaluated. The internal microstructure was reconstructed using XCT and the open porosity structures were revealed. The influence of both the porosity and the HAp reinforcement on the mechanical properties was observed. Additionally, a thermal DSC analysis was carried out, which allowed to assess how the filler and process parameters affect the degree of crystallinity of the obtained structures and the thermal degradation of the composite. In general, the presented study shows the possibility of designing part properties not only by means of the DBLS process parameters but also by influencing the powder material properties. Both raw material properties and process parameters affect the morphology of pores and therefore the mechanical properties of PBF processed material.
This study investigated the application of biologically active compounds from algae obtained by supercritical carbon dioxide extraction (SC–CO2) as plant growth biostimulants. This study investigated, extracts from the Spirulina (Arthrospira) platensis. Plant tests confirmed the beneficial effect of the formulation containing SC-CO2 extract of S. platensis and micronutrients on the initial phase of wheat growth (germination tests) and wheat and rapeseed yield (field tests). No phytotoxicity was observed with the treatments. The highest number of siliques was obtained for the formulation containing SC-CO2 extract of S. platensis and amino acids. Mycological studies demonstrated the efficacy of the SC-CO2 extract of S. platensis against six of the nine fungal pathogen strains tested. It was confirmed that the formulation containing SC-CO2 extract of S. platensis effectively reduced the development of the pathogen and had beneficial effects on the initial growth phase of wheat (germination tests) and the yield of wheat and rapeseed (field tests). Using of algae and fatty acids from their extraction as biostimulants offers the possibility of reducing fertilizer doses – it is a promising tool to enhance plant production in the global climate crisis.
In this work, the laser microtexturing is exploratory studied for controlling the interface between the oxidation resistant metallic bond coat and thermally insulating ceramic top coat in Thermal Barrier Coatings. The 80 to 100 μm thick NiCrAlY layer was deposited by Atmospheric Plasma Spraying over the nickel-based super alloy substrate. Then, the infrared fiber nanosecond laser was used for shaping the topography of bond coat prior to the top coat deposition. The surface geometry was adapted by selecting the laser set-up operational conditions, mainly: (i) laser power, (ii) frequency, (iii) scanning velocity and (iv) inter-pass spacing. The two groove-based patterns were finally selected for further work together with one as-sprayed bond coat, as a reference. The 8 wt% yttria stabilized zirconia (8YSZ) was deposited by means of Suspension Plasma Spraying over all three types of bond coats. The samples were then subjected to isothermal oxidation and thermal cyclic fatigue testing in order to study the influence of bond coat topography on the overall behavior of coatings under high temperature conditions. The microstructural studies revealed that the as-sprayed bond coat topography may be progressively modified by multistep laser microtexturing. The uniform bond coat topography is found to be beneficial in promoting formation of homogeneous, columnar-like top coat. However, the modification of bond coat topography affects the behavior of the bond coat/top coat interface during high temperature testing. The study shows that the microtexture depth should be precisely controlled, otherwise the through bond coat thickness oxidation is observed, which has a detrimental effect on the overall durability of the TBC system. The bond coat asperity width plays also an important role. If it is too narrow, then the failure may propagate locally through the bond coat or the thermally grown oxide layer.
The paper presents technological and microstructural aspects of welding and post-weld heat treatment of the S355 constructional steel welded joints. It was found that welding this steel resulted in a wide heataffected zone with diverse microstructures conducive to lower abrasive-wear resistance and worse mechanical characteristics of the steel. In this connection, the welding technique of the S355 steel was suggested, as well as conditions and parameters of the post-weld heat treatment, which made it possible to obtain – in the entire welded joint area – the microstructures characterised by high mechanical properties and increased resistance to abrasive wear. It was shown that the suggested set of technological operations applied to the S355 steel resulted, under laboratory conditions, in a significant increase of relative abrasive-wear resistance, determined by the abrasion test with use of the of loose aloxite 90.
Transmission electron microscopy is a basic technique used for examining matter at the highest magnification scale available. One of its most challenging branches is in situ microscopy, in which dynamic processes are observed in real time. Among the various stimuli, like strain, temperature, and magnetic or electric fields, the light-matter interaction is rarely observed. However, in recent years, a significant increase in the interest in this technique has been observed. Therefore, I present a summary and critical review of all the in situ experiments performed with light, various technical possibilities for bringing radiation inside the transmission electron microscope, and the most important differences between the effects of light and electrons on the studied matter. Finally, I summarize the most promising directions for further research using light excitation.
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10,086 members
Bartosz Zajaczkowski
  • Faculty of Mechanical and Power Engineering
Leszek Piotr Jurdziak
  • Faculty of Geoengineering, Mining and Geology
Pawel Pohl
  • Faculty of Chemistry
Edward F. Plinski
  • Faculty of Electronics
Information
Address
Wybrzeze Wyspianskiego 27, 50-370, Wrocław, dolnoslaskie, Poland
Head of institution
Arkadiusz Wójs
Website
www.pwr.edu.pl
Phone
48713202600