Polish Conditions Research Articles

Optimizing Eurasian Perch Production: Innovative Aquaculture in Earthen Ponds Using RAS and RAMPS—Economic Perspective

Aquaculture in rural areas, carried out in accordance with current EU requirements, aims to contribute significantly to the conservation of the biodiversity of aquatic resources, the protection of which is a prerequisite for sustainable economic and social development. The objective of this study was to present the conceptual and technical framework and to analyze the costs and profitability of producing the consumer-attractive Eurasian perch (Perca fluviatilis L.) based on the untapped potential of hatchery infrastructure and dedicated earthen ponds for common carp (Cyprinus carpio L.) production. The experiments were conducted under Polish conditions, but the results/methods can be successfully applied in other countries, mainly in Central and Eastern Europe, where production in earthen ponds is the basis of aquaculture production. The analysis of the profitability of the venture shows that the cost structure was dominated by labor and feed inputs. Despite high variable costs, this type of production can be profitable and contribute to food security and economic development in line with the EU’s Blue Growth Strategy. The article also analyzes the potential opportunities and risks of fish production based on the Recirculating Aquaculture System (RAS) and the Recirculating Aquaculture Multitrophic Pond System (RAMPS).

Effect of Crop Protection Intensity and Nitrogen Fertilisation on the Quality Parameters of Spelt Wheat Grain cv. ‘Rokosz’ Grown in South-Eastern Poland

Spelt wheat is one of the oldest wheats cultivated by humans. It is characterised by high nutritional values and is sought after by consumers. Additionally, it does not have high habitat and fertilisation requirements and is resistant to diseases. The aim of this study was to determine the effect of different levels of nitrogen fertilisation and the intensification of fungicide protection on the grain quality characteristics of spelt cv. ‘Rokosz’ grown under south-eastern Polish conditions. The present research showed that the intensification of fungicide crop protection and increasing the nitrogen dose from 70 to 130 kg ha−1 had a positive effect on the quality features of spelt grains. The highest protein, gluten and starch contents were found after four fungicide treatments. These parameters increased their values under the influence of fungicides. After the application of 130 kg ha−1, spelt wheat grain had the most favourable chemical composition, containing the most protein, gluten, soluble dietary fibre, insoluble dietary fibre and fat. It also had a positive effect on the Zeleny sedimentation index and the amino acid content of the grain. Due to the favourable response of the spelt cv. ‘Rokosz’ to intensified fungicide protection and nitrogen fertilisation, it should be recommended for cultivation in integrated technology.

Fusarium Species Shifts in Maize Grain as a Response to Climatic Changes in Poland

Maize, along with wheat and rice, is the most important crop for food security. Ear rots caused by Fusarium species are among the most important diseases of maize. The distribution of Fusarium species provides essential epidemiological information for disease management. The effect of weather conditions, climate change and geographic localization on the Fusarium population in Poland was evaluated between 2015 and 2018. Grain samples (n = 233) were collected from hybrids at 16 locations (L1–L16). The differences in altitude between locations ranged from 39 to 243 m above sea level, longitude varied between 15°55′ and 23°12′ E, and latitude spanned from 50°12′ to 54°01′ N. Isolates were identified using molecular techniques. The highest Fusarium species frequency was recorded for 2016 (30.70%) and 2017 (28.18%), and the lowest for 2018 (5.36%). F. verticillioides and F. temperatum were the most frequent. Altitude has an effect on F. vericillioides frequency: F. graminearum showed a negative correlation with both latitude and longitude. In Polish conditions, from silking to harvesting, the number of days with higher precipitation and lower temperatures is associated with an increased frequency of F. verticillioides, F. temperatum, F. graminearum and F. avenaceum. This suggests that the Fusarium presence in Poland is significantly influenced not only by climate change but also by extreme weather changes.

The Performance of Solar Still in Continental Climates: A Case Study in Poland

This paper addresses the global issue of water scarcity and the need for sustainable development by exploring eco-friendly desalination technology – solar still. Although solar still has lower productivity compared to conventional fossil-fueled desalination technologies, much research is being conducted to enhance its productivity. Most studies focus solely on optimizing water mass in solar still, neglecting other correlated factors. Hence, this paper presents mathematical modeling and experimental studies on the impact of water mass, initial temperature, and solar insolation on solar still performance in Polish weather conditions. The findings reveal that solar still productivity ranges from 215 mL/m2/day to 5079 mL/m2/day between June and October in Poland. It is observed that solar still productivity decreases with increasing water mass beyond the critical threshold of solar insolation on the glass cover plane, which is 2.676 kWh/m2/day. However, below that threshold, the effect of water mass on the solar still productivity strongly depends on its initial temperature.

Validity and reliability of the Polish version of the Pregnancy Mobility Index (PMI-PL).

Mobility, defined as active, controlled, multi-joint flexibility used in movement, is limited in pregnant women due to problems with low back pain (LBP) and pelvic girdle pain (PGP). The Pregnancy Mobility Index (PMI) is a tool for assessing mobility in relation to LBP/PGP. The lack of a Polish version of the PMI test prompted a transcultural adaptation to the Polish conditions. The aim of the study was to evaluate the measurement properties of the Polish adaptation of the Pregnancy Mobility Index. The study involved 121 pregnant women aged 18-44. The translation process was in accordance with the transcultural adaptation design. Reliability was assessed by intraclass correlation coefficient (ICC). Construct validity between the Polish version of the PMI (PMI-PL) and the Physical Activity Pregnancy Questionnaire (PPAQ-PL) was assessed by Spearman's rank correlation coefficient. The transcultural adaptation of the PMI test into Polish was satisfactory, with high internal consistency (Cronbach's alpha = 0.97-0.98, ICC = 0.989). Statistically significant inverse proportional correlations were found for total PA, total PA (light and above), light PA, moderate PA, and vigorous PA in the construct validity analysis between PMI-PL and PPAQ-PL. The Polish version of the PMI is a reliable instrument. The introduction of a questionnaire with a classification system will make it easier for health professionals to monitor the health status of pregnant women and encourage them to engage in physical activity appropriate for their current level of mobility.

Development and tests of the novel configuration of the solar chimney with sensible heat storage

Heating, ventilation, and air conditioning systems account for a significant part of the energy usage in buildings and are primarily responsible for greenhouse gas emissions and operating costs. These can be lowered by the adoption of solar energy. This paper presents the developing and testing of a novel solar chimney with sensible heat storage. The thermal performance and potential contribution of the developed thermal chimney to decreasing residential buildings energy consumption in Polish climate conditions is investigated. The developed solar air chimney is composed of a novel accumulation material that allows for sensible heat storage. Solar radiation can heat the accumulation layer during the day and the stored energy can be used to preheat the ventilation air. The prototype of the solar chimney was tested in laboratory conditions using a dedicated experimental rig. Furthermore, numerical calculations were performed using TRNSYS software, where a validated dynamic numerical model was developed to simulate the performance of the device. The results show that airflow direction, volume, and the number of heated walls significantly impact the power transferred from the solar chimney walls to the air. The maximum power transferred from the solar chimney walls to the air per unit of surface varied from 360.2 W/m2 (when all walls were heated) to 672.4 W/m2 (when only one wall was heated). The validated model underestimates the outlet air temperature of the solar chimney by a maximum of 0.39 °C on average basis and shows that the increase of air temperature between −10 and 20 °C at 1000 W/m2 determines a decrease of 12.5 % of the thermal output. The obtained results allow one to highlight that the proposed solution can be considered as a replacement for typical brick chimneys located on roofs or as a thermal storage wall.

A Novel and Simplified Anion Exchange Flow-Through Polishing Approach for the Separation of Full From Empty Adeno-Associated Virus Capsids.

Adeno-associated viruses (AAV) are widely used viral vectors for in vivo gene therapy. The purification of AAV, particularly the separation of genome-containing from empty AAV capsids, is usually time-consuming and requires expensive equipment. In this study, we present a novel laboratory scale anion exchange flow-through polishing method designed to separate full and empty AAV. Once the appropriate conditions are defined, this method eliminates the need for a chromatography system. Determination of optimal polishing conditions using a chromatography system revealed that the divalent salt MgCl2 resulted in better separation of full and empty AAV than the monovalent salt NaCl. The efficacy of the method was demonstrated for three distinct AAV serotypes (AAV8, AAV5, and AAV2) on two different stationary phases: a membrane adsorber and a monolith, resulting in a 4- to 7.5-fold enrichment of full AAV particles. Moreover, the method was shown to preserve the AAV capsids' functional potency and structural integrity. Following the successful establishment of the flow-through polishing approach, it was adapted to a manual syringe-based system. Manual flow-through polishing using the monolith or membrane adsorber achieved 3.6- and 5.4-fold enrichment of full AAV, respectively. This study demonstrates the feasibility of separating full and empty AAV without complex linear or step gradient elution and the necessity of specialized equipment. Flow-through polishing provides a rapid and easy-to-perform platform for polishing multiple vector preparations, addressing a critical aspect in the research and development of novel gene therapies.

Effect of Bacterial Infection By-Products on the Corrosion of Titanium Osteo-Implants

The use of titanium (Ti) in dental and orthopedic implant applications is extensive, owing to its remarkable resistance to corrosion, biocompatibility, low density, mechanical strength, and elastic modulus, which closely aligns with bone properties compared to alternative metals 1. There are numerous titanium grades (40-50), only a select few are officially recognized and specified by the American Society for Testing and Materials (ASTM) for use in biological applications. Biomedically compatible grades 1–4, classified as commercially pure (cp-Ti), contain <1% alloying elements, while others are considered Ti alloys with a higher percentage of alloying elements. Among titanium alloys, grade 5 Ti (Ti6Al4V) is predominantly utilized in orthopedic implants 2.Approximately 800,000 knee replacement surgeries are performed annually in the United States alone 3. Projections indicate an anticipated four million joint replacements (hip, knee, and shoulder) annually in the US by 2030 4. Infection rates for orthopedic implants are reported to be below 2%, with the majority occurring within the initial 2 years post-operation 4. The ten-year survival rate for orthopedic implants stands at 85-90% 5 and only 58% of patients can expect their hip replacements to endure for 25 years 6. Implant failure often necessitates revision surgery, incurring high costs, a relatively low success rate, and considerable patient discomfort. Corrosion, arising from the dissolution of titanium and/or alloying elements from the implant, is a prevalent cause of orthopedic failure 7.Surgical procedures, compromising the skin barrier and introducing foreign materials during joint replacement, predispose the body to infection, including bacteria that form biofilms. Gram-negative bacteria are a source of lipopolysaccharide (LPS) 8. Joint movements have the potential to rupture biofilms, releasing LPS into the synovial fluid surrounding the joint. This study aims to explore the impact of LPS in synovial fluid on implant corrosion.The study utilized simulated synovial fluid (SSF) and LPS from Escherichia coli, employing electrochemical techniques to investigate corrosion behavior. Titanium grade 2, 4, and 5 were evaluated for corrosion under unpolished and polished conditions, with and without the presence of LPS in SSF at 37℃ (Figure 1). The unpolished Ti surface consist of titanium with an oxide protective layer on top, as a fresh titanium surface naturally develops a protective oxide layer of titanium oxides when exposed to air or aqueous environments 9. The corrosion resistance of this natural TiO2 layer was examined in the presence of LPS. Furthermore, the disruption of the native oxidation film on the implant surface due to joint movement was examined as a potential factor that may accelerate corrosion. Consequently, the self-healing process of titanium oxide layers emerges as crucial in mitigating failures in orthopedic implants. The influence of LPS on this self-healing process was explored by immersing polished titanium in SSF both with and without LPS for a duration of 80 days. The corrosion current density was measured for all cases using linear sweep voltammetry (LSV) and fitting the data to the Butler-Volmer equation. The native oxide layer was indeed found to be protective compared to the naked metal and the “self-healing” of this film overtime was found to significantly reduce corrosion rates over the 80-day test. Interestingly, LPS was found to both reduce the protective effect of the native layer and disrupt the self-healing process. Electrochemical oxidation of the Ti surface was found strengthen the corrosion resistance of the native film and found to offer a simple pathway towards enhanced corrosion resistance even in the presence of LPS. We propose a mechanism for the LPS effect and conclude that post-operative bacterial infections can significantly exacerbate the corrosion of Ti osteo-implants and increase the likelihood of implant failure. Reference: G. Szczęsny, M. Kopec, D. J. Politis, Z. L. Kowalewski, A. Łazarski, and T. Szolc, Materials (Basel), 15 (10), (2022).J. Quinn, R. McFadden, C.-W. Chan, and L. Carson, iScience, 23 (11), 101745 (2020).G. Castillano, Total Orthopaedic Care, (2022).A. Connaughton, A. Childs, S. Dylewski, and V. J. Sabesan, Frontiers in medicine, 1 22 (2014).R. M. Grzeskowiak, J. Schumacher, M. S. Dhar, D. P. Harper, P. Y. Mulon, and D. E. Anderson, Frontiers in surgery, 7 601244 (2020).J. T. Evans, R. W. Walker, J. P. Evans, A. W. Blom, A. Sayers, and M. R. Whitehouse, The Lancet, 393 (10172), 655-663 (2019).Y. Bao, A. I. Muñoz, C.-O. A. Olsson, B. M. Jolles, and S. Mischler, Materials (Basel), 15 (5), 1726 (2022).C. R. Raetz and C. Whitfield, Annual review of biochemistry, 71 (1), 635-700 (2002).I. Milošev, T. Kosec, and H. H. Strehblow, Electrochimica Acta, 53 (9), 3547-3558 (2008). Figure 1

Does dental material type influence bacterial adhesion under the same polishing conditions? Direct observation using a fluorescent staining technique: An in vitro study.

Highly polished 3, 4, and 5 mol% yttria-stabilized zirconia and CAD/CAM composite resin samples were prepared, and the influence of surface roughness (Ra and Sa, 21 areas/group), wettability (contact angle and surface energy, 3 samples/group), and surface chemical composition (2 samples/group) on single-strain bacterial adhesion models (Porphyromonas gingivalis, Streptococcus oralis, Streptococcus sanguinis, Streptococcus gordonii, and Streptococcus mutans) were compared via fluorescent staining with graphical analysis (21 areas/group). Statistical analysis was performed using the Shapiro-Wilk test followed by one-way analysis of variance with Tukey's test or the Kruskal-Wallis test with Dunn's test (α=0.05) and linear regression. For dental zirconia with the same surface roughness, the yttria content did not significantly influence the initial bacterial adhesion. However, higher bacterial adhesion was detected for the composite resin owing to its high C, O, and Si contents. There was no correlation between surface energy and bacterial adhesion for any bacterial strain (p<0.005).

Digital Energy Path for Planning and Operation of the sustainable grid, products and society – project objectives and selected preliminary results in Polish conditions

Digital Energy Path for Planning and Operation of the sustainable grid, products and society – project objectives and selected preliminary results in Polish conditions

Evaluating Friction Characteristics of High Friction Surface Treatment Application Under Varied Polishing and Slippery Conditions

The frictional attributes of high friction surface treatment (HFST) play a crucial role in ensuring optimal traffic safety, particularly in wet weather conditions. Friction consists of two important components: adhesion and hysteresis. This research focuses on evaluating these essential factors in HFST using two different aggregates and two distinct sizes by considering various abrasion and polishing methods. To isolate these components for assessment, testing was carried out under various slippery conditions, including dry, wet with water, and wet with water + soap. The inclusion of liquid hand soap in the test procedure effectively minimized or even eliminated the adhesion component’s influence, making it possible to primarily focus on the hysteresis component. Consequently, the British Pendulum Number (BPN) measured in this research predominantly reflected the hysteresis-related friction. The analysis of variance results emphasized the substantial impact of different abrasion and polishing methods on the BPN values obtained under various surface conditions. Notably, Micro-Deval Abrasion (MDA) with 105, 180, and 240 min abrasion exhibited the most pronounced influence on BPN variation and the higher F-value for the MDA 105 min indicated that this specific abrasion time exerted a more significant influence on the variation in BPN values than other factors. Furthermore, the utilization of the Aggregate Image Measurement System yielded valuable insights into the micro-texture of the aggregates. It revealed that the calcined bauxite HFST size is anticipated to provide the rougher surface morphology (texture) on a pavement surface compared with other sources in this study, thereby contributing to high pavement surface friction. The findings from this study contribute to a deeper understanding of the frictional characteristics of HFST under different scenarios, providing valuable insights for optimizing HFST applications to enhance road safety and skid resistance.

Fertility and quality of arable soils in Poland: spatial–temporal analysis of long-term monitoring

Soil quality is a globally important issue from the point of view of food production, maintenance of appropriate environmental quality and ecological balance. Assessing its quality and fertility using indices is one of the methods that make it possible to formulate recommendations for good soil management. The aim of the study was, therefore, to determine the spatial and temporal distribution of soil properties in the context of soil quality assessment (SQI) and soil fertility assessment (SFI, SEF, NIV, and SSFI) using the example of a Central European country (Poland). The inverse distance-weighted spatial interpolation technique was used to estimate the spatial distribution of soil quality and fertility indicators. So far, no research has been carried out that would include a comprehensive analysis of soil fertility and quality indicators in such a large research area over many years. The results of 216 points of monitoring the chemistry of arable soils in Poland from the period 1995–2020 for 28 physicochemical soil parameters were considered. The analyses carried out showed significant variability in the properties of the described soils in Poland, as evidenced by the principal component analysis (PCA) and the coefficient of variation (exceptions: bulk density, pH). It was found that heavy metals (Zn, Cd, Cu) were responsible for the deterioration of soil properties. The results obtained for different indices were different (SFI – most soils with good fertility, SEF – high fertility, NIV – soils highly enriched with nutrients, SQI – average soil quality). It was found that the SSFI is the most appropriate indicator among the analyzed indicators for Polish conditions in relation to arable soils, as it is adapted and calibrated to the specifics of this area. The Spearman correlation matrix showed that the largest group of statistically highly significant parameter pairs belonged to heavy metals (Ni/Zn, Zn/Pb, Zn/Cu, Ni/Cu). In contrast, the strongest correlations were recorded for Ni (with effective cation exchange capacity (ECEC), Mn, Mgav, Zn, Cu). The assessment revealed limiting factors and temporal trends in the overall evaluation of the quality of the country’s agricultural soils, which are important from the point of view of both sustainable development and agricultural production.

General problems of the cadastre system - case study in Poland

Motives: The proper functioning of land administration systems guarantees the security of property rights and property trading rights, which is why many countries worldwide are carrying out continuous research aimed at harmonising and modernising the cadastral system. Aim: The aim of this article is to show the effects of the implementation of the global concepts of the cadastral system evolution under Polish conditions. This problem is international in nature, and common for a group of central and eastern European countries that underwent a systemic transformation at the end of the 20th century. Results: As demonstrated in the case study, the cadastral system maintained in Poland is not uniform. There are still many areas where the basic source of information about properties is the materials from the 1960’s and 1970’s. Nevertheless, the gradually conducted modernisation of the Land and Buildings Registry, which is based on international standards and norms, is slowly leading to the establishment of a full-fledged cadastral system.

Storing Electric Energy Generated by a Photovoltaic Installation to Increase Profit from Its Sale—Case Study in Poland

Battery systems enable the sustainable use of energy from renewable energy installations that are characterized by variable time availability. The present study investigated the benefits of implementing an electrical energy storage system to a photovoltaic (PV) installation in the Polish climatic conditions. The impact of such a system on increasing profits from energy sales was verified. The use of storage allows for shifting the process of feeding energy into the grid to later hours when it is more expensive. The production volume and timing of energy generation were considered using the example of a 5 kWp research installation located in the Laboratory of Renewable Energy. The yields and energy prices were analyzed on an hourly basis for the year 2023. The considered system is additionally equipped with a battery with a capacity of 15 kWh. Analyses have shown that this system covers 55.6% of days in a year where the entire daily production from the PV installation can be stored. Additionally, the feasibility of using different energy storage capacities to shift the sale of the maximum energy volume was examined. Also the payback period of investments was considered for four scenarios (from the most expensive devices to the cheapest ones with subsidies). Prices were compared with profits resulting from the use of storage systems of a given capacity, as well as with the lengths of warranties covering the devices.

Influence of the as-built surface and a T6 heat treatment on the fatigue behavior of additively manufactured AlSi10Mg

As the fatigue strength of materials manufactured via lase-based powder bed fusion (PBF-LB) is highly influenced by process-induced defects and the “as-built” surface, in this work fatigue tests at specimens made of AlSi10Mg with “as-built” and polished surface condition were conducted. In this context also the defect tolerance of the material, and hence its ability to counteract process-induced notch effects, was analyzed. For this, specimens in a not heat-treated and an artificially aged (T6) condition were tested. For the not heat-treated specimens, a high reduction of the fatigue strength due to the “as-built” surface is observed, while the heat-treated specimens exhibit no influence of the surface condition. Using the √area approach, it is demonstrated that the smaller fatigue strength due to “as-built” surface observed for the not heat-treated condition results from process-related residual tensile stresses, which are removed by T6 heat treatment and polishing, respectively. Moreover, the results show that the “as-built” surface leads to similar stress concentrations than defects in the specimen volume, and thus, polishing had no influence on the fatigue performance after heat treatment. In addition to these findings, an increased fatigue strength after T6 heat treatment was observed, which is caused by an increased defect tolerance.

Wpływ zmian klimatu na środowisko zabudowane

We are currently in the period of an intensive climate change, resulting from changes in the heat balance of the earth’s surface and causing an increase in the temperature of the lower troposphere levels. According to the latest IPCC report of 2021, it is human activity that has indisputably caused the increase in atmospheric concentrations of greenhouse gases, responsible for this process. The consequences of climate change under Polish conditions, apart from a rise in temperature especially in the spring and winter months, are also changes in the amount and distribution of precipitation totals. A slight increase in precipitation totals is observed, however heavy rainfall is significantly more frequent, interspersed with periods of droughts and heatwaves. Ground frost-free periods are prolonged, and a negative trend in the duration and thickness of snow cover is recorded in most parts of the country. Although extreme phenomena occurring in Poland are permanently inscribed in its climatic conditions, the threat of strong winds has been increasing in recent years, and the intense precipitation that often accompanies them is the cause of peak discharges and flooding. Forecasts for progressive climate change are not optimistic, either on a global scale or for the country in question. The article examines the impact of climate change on the design, construction and maintenance of engineering structures globally and for Poland. Changes in design standards, selected examples of disasters and solutions to adapt and build resilience to climate change have been analysed. For most building disasters, climatic factors were the direct cause of the disaster, although in the course of the analysis it has usually turned out that the disasters exposed human errors in the design, construction and, to a lesser extent, the improper maintenance of engineering structures. However, there is an increasing number of new approaches to creating a climate change resilient built environment, including the latest one, which proposes to use the grey infrastructure of cities to build resilience to climate change.

Development of Ce/Cu co-doped dendritic mesoporous silica nanoparticles (DMSNs) as novel abrasive systems toward high-performance chemical mechanical polishing

Development of novel abrasive systems with functional activities and physicochemical properties are of great significance in the reactive oxygen species (ROS)-enhanced chemical mechanical polishing. In this work, Ce single-doped and Ce/Cu co-doped dendritic mesoporous silica nanoparticles (DMSNs), namely Ce−DMSNs and Ce/Cu−DMSNs, were produced via a simple impregnation and thermolysis procedure. The Ce and/or Cu species involved in DMSNs frameworks were characterized through X-ray diffractometry, infrared spectroscopy, scanning electron microscopy, energy dispersive spectrometry, transmission electron microscopy, X-ray photoelectron spectroscopy, and nitrogen adsorption/desorption techniques. We report the evolution of surface morphology and roughness, defects, peak-to-valley data, image surface area difference, and material removal efficiency during ROS-enhanced polishing experiments toward silica materials. All the pure, Ce single-doped, and Ce/Cu co-doped DMSNs abrasive systems offered nearly defect-free surfaces with close-to-atom scale roughness. It might be attributed to the “springlike effect” and “soft polishing/abrasion”, possibly originating from the low-modulus DMSNs carriers. Among these abrasives, the Ce/Cu co-doped DMSNs systems achieved an evident improvement in removal efficiency, especially under ultraviolet irradiation-assisted polishing conditions. The coexisted Ce(Ⅲ)/Ce(Ⅳ) and Cu(Ⅰ)/Cu(Ⅱ) couples might be responsible for the effective production of ROS in photocatalysis and Fenton-like processes, thereby contributing to the Si–OH and Ce(Ⅲ)−O–Si bonding formations. The role of the developed Ce/Cu co-doped DMSNs abrasive systems in ROS-enhanced polishing processes was discussed.

Influence of surface finishing by grinding on the cavitation erosion resistance of 316L and NiAl-bronze

Improving the mechanical properties of bulk and near-surface materials and alternating the dynamics of cavitating bubbles are two main methods to reduce cavitation erosion damage. Grinding and polishing, as two common surface finishing stages, can alter the cavitation erosion damage on metallic materials by affecting both the bubble dynamics and the mechanical properties of the surface. In this paper, the ultrasonic cavitation erosion resistance of 316L and NiAl-bronze alloys, each with two initial surface conditions of grinding and polishing is investigated, focussing on the material reaction. The mechanisms of material removal are discussed based on surface and subsurface observations to explain the effect of surface finishing on the cavitation erosion damage. After 8.5 h cavitation erosion testing time, a lower erosion mass loss was obtained for both alloys in the ground state as compared to the polished state suggesting that grinding can improve the cavitation erosion resistance of alloys. On the other hand, the polishing process improved the erosion resistance of NiAl-bronze at the early stages of cavitation. This is discussed in light of the two distinct surface characteristics of roughness and hardness, which, in turn, tend to increase and decrease cavitation erosion damage. Planar crystallographic boundaries and intermetallic-matrix interfaces were found to be the most susceptible sites to early erosion damage on the polished 316L and bronze, respectively.

Development of the Polish Power Sector towards Energy Neutrality—The Scenario Approach

This article discusses three scenarios for the transformation of the Polish power system leading to the achievement of climate neutrality through investment in renewable energy sources. The scenarios differ in terms of the role played by the selected energy technologies. The scenarios were developed using the balancing tool, the Simulator Polish Power System, which analyzed the development of the national power system in terms of optimal costs of achieving climate neutrality and the lowest possible price of electricity generation. The research shows that under Polish climatic conditions, 100% RES energy can be achieved in the balance, but ensuring the continuity of energy supply, which in future will be generated mainly from this type of source, requires the participation of controllable sources such as gas-fired power plants powered by biomethane and energy storage facilities. The scenarios assume balancing RES sources with 15–25 GW of available gas sources and 40 GWh in electricity storage. The article also discusses factors limiting the suggested scenarios, such as the availability of sustainable biomethane in Poland or limitations associated with the possibility of building onshore and offshore wind turbines.

Possibilities of natural hydrogen deposits in Polish conditions

W artykule przedstawiono wodór naturalny jako potencjalne bezemisyjne źródło energii odnawialnej, która w transformacji energetycznej całej gospodarki ma do odegrania niezwykle ważną rolę. Omówiono drogi migracji i akumulacji wodorowych. Podano przykłady występowania wodoru w różnych typach środowiska naturalnego i w różnych strukturach litologiczno-stratygraficznych, także na obszarach oceanicznych i w strefach występowania podwyższonej aktywności wulkanicznej. Przedstawiono źródła pochodzenia wodoru naturalnego, z których za najważniejsze przyjmuje się proces serpentynizacji, typowy dla skał ultrazasadowych bogatych w żelazo. Obecnie uważa się, że proces ten może generować aż 80% wodoru występującego na Ziemi. Innym procesem uczestniczącym w produkcji wodoru jest radioliza, zachodząca w skałach zawierających pierwiastki promieniotwórcze (m.in. U, Th), emitujące promieniowanie jonizujące i powodujące rozszczepianie cząstek wody. W czasie tej reakcji uwalniany jest wodór. Zaprezentowano wybrane prace badawcze prowadzone w Polsce na przestrzeni lat, w których zwrócono uwagę na obecność wodoru w gazach ziemnych związanych ze złożami węglowodorów czy ze złożami rud metali. Przeanalizowano 160 wyników badań składu gazów z otworów wiertniczych zlokalizowanych w rejonie północno-zachodniej Polski. Można zauważyć bardzo zmienne zawartości wodoru w tych próbkach. Jego zdecydowanie wyższe stężenia obserwuje się w utworach czerwonego spągowca, zaś znacznie niższe w utworach karbonu, dewonu i kambru. Obecność wodoru jest związana nie tylko z litostratygrafią, ale także z budową tektoniczną danego obszaru. Przedstawiono kierunki prac badawczo-rozwojowych, które powinny być choć w części prowadzone na etapie wstępnej oceny możliwości występowania pułapek wodorowych i określenia ich potencjału.