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Investigation of the properties of low water-to-solid ratio vibro-press-formed alkali-activated municipal solid waste incineration bottom-ash concrete /
No full textThis work focuses on the use of municipal waste incineration bottom ash (MSWI) for the development and production of products suitable for use as construction products. The generation of these ashes is increasing every year due to the incineration of municipal waste. There are currently three incineration plants operating in major cities in Lithuania. The non-hazardous bottom ash remaining from the incineration process is stored in dedicated sorting and aging sites until it is used as an inert form of aggregate for the installation of road foundations. However, it has been observed that these ashes have a tendency to bind and cement when exposed to atmospheric precipitation at the storage site. Based on this characteristic, it was decided in this study to use alkaline activation of the ash to accelerate the bonding process and to create a dense, non-porous composite concrete structure. This activation method is known to create another problem during ash bonding, where the presence of metallic aluminum particles in the ash leads to the release of hydrogen gas and makes the structure of the cured samples porous. For the purposes of the study, it was decided to create a completely different mixture structure and not to use additional water in the mixtures tested. A very low water/solids ratio (W/S) of <0.08 was used for the alkaline activation of the mixtures. All the water required for ash activation was obtained from sodium silicate and sodium hydroxide solution. Metakaolin waste (MKW) was used to adjust the SiO2/Na2O/Al2O3 ratio of the mixtures. Vibro-pressing was used to form and increase the density of the samples. And for the formation of the concrete structure, 0/4 fraction sand was used as aggregate. The final alkali-activated sample obtained had properties similar to those of the very widely used vibro-pressed cementitious paving tiles and did not exhibit hydrogen evolution during alkali activation due to the very low W/S ratio. The best results were achieved by samples with a highest compressive strength of 40.0 MPa and a tensile strength of 5.60 MPa, as well as a density of 1950 kg/m3. It is believed that this alkaline activation and vibro-pressing method can expand the use of MSWI ash in the development of building products
Biotechnological valorization of brewer’s spent grain from old bread and barley malt: fermentative potential of saccharomyces cerevisiae /
No full textBrewer’s spent grain (BSG), the most abundant by-product from breweries, is mainly discarded or used as animal feed. However, to increase the brewing sustainability, biotechnological utilization of BSG is a much preferred solution. This study examined the fermentation of BSG, composed of old wheat bread and barley malt, by metabolic activity of Saccharomyces cerevisiae on both hydrolyzed and non-hydrolyzed media. Enzymatic hydrolysis with Viscozyme® W FG for 6 h was selected as the most effective and was used in the further research step to prepare the hydrolyzed BSG-based medium. Both media supported almost uniform yeast growth (numbers of S. cerevisiae cells was about 8 log10 CFU/g) in an acidic environment (pH value was about 5), but fermentation of hydrolyzed BSG resulted in 20% higher sugar consumption and 10% higher total titratable acidity. These findings underscore the potential of enzymatic pretreatment to improve fermentation performance. The adaptability of S. cerevisiae and the fermentability of both substrates suggest promising potential for scalable BSG valorization strategies in circular food systems
Sustainable production and antioxidant activity of bacterial xanthan gum /
No full textOne of the world's most sustainable solutions is to replace fossil-based polymers with biopolymers. The production of xanthan gum can be optimized using various renewable and cost-effective raw materials, which is a key focus in industrial biotechnology. Xanthan gum is a bioengineered thickening, stabilizing, and emulsifying agent. It has unique properties for use in many industries (food, biotechnology, petrochemicals, agricultural, cosmetics, wastewater treatment) and medical applications. It is tasteless, environmentally safe, non-toxic, and biodegradable. The biotechnological production of xanthan gum depends on several factors: bacterial strain development, culture medium preparation, carbon sources, fermentation parameters and modes, pH, temperature, recovery, purification, and quality control regulations. Bio-innovative strategies have been developed to optimize the production of xanthan gum. A variety of carbon and nitrogen sources, as well as alternative renewable sources, have been used in the production of xanthan gum. The aim of the present study was to optimize the xanthan gum yield using Xanthomonas campestris bacteria and different carbon (D-glucose, D-sorbitol, lactose, sucrose, D-mannitol, D-fructose, erythritol, coconut palm sugar, L-arabinose, unrefined cane sugar), various nitrogen (bacterial peptone, casein peptone, L-glutamic acid, L-arginine, L-methionine, L-tryptophan, malt extract, meat extract, L-phenylalanine, soy peptone) and alternative carbon (orange peels, tangerine peels, lemon peels, avocado peels, melon peels, apple peels, cellulose, xylose, xylitol) sources. The xanthan gum samples were analyzed using antioxidant methods. Our study showed that using L-glutamic acid as the carbon source for 72 h of bacterial fermentation of Xanthomonas campestris resulted in the highest xanthan gum yield: 32.34 g/L. However, using renewable resources, we achieved a very high concentration of xanthan gum in just 24 h of fermentation. According to the reducing power and DPPH methods, the highest antioxidant activities were measured for xanthan gum whose biosynthesis was based on renewable resources. Xanthan gum structures have been verified by FT-IR and 1H NMR analysis. The sustainable biotechnology study has the advantage of increasing the sustainable production of xanthan gum by using renewable alternative resources compared to other production processes. Xanthan gum continues to be a valuable biopolymer with a wide range of industrial applications while promoting environmentally friendly production practices
Experimental study of lidar system for a static object in adverse weather conditions /
No full textThanks to light detection and ranging (LiDAR), unmanned ground vehicles (UGVs) are able to detect different objects in their environment and measure the distance between them. This device gives the ability to see its surroundings in real time. However, the accuracy of LiDAR can be reduced, especially in rainy weather, fog, urban smog and the like. These factors can have disastrous consequences as they increase the errors in the vehicle’s control computer. The aim of this research was to determine the most appropriate LiDAR frequency for static objects, depending on the distance to them and the scanning frequency in different weather conditions; therefore, it is based on empiric data obtained by using the RoboPeak A1M8 LiDAR. The results obtained in rainy conditions are compared with the same ones in clear weather, using stochastic methods. A direct influence of both the frequencies used and the rain on the accuracy of the LiDAR measurements was found. The range measurement errors increase in rainy weather; as the scanning frequency increases, the results become more accurate but capture a smaller number of object points. The higher frequencies lead to about five times less error at the farthest distances compared to the lower frequencies
Opportunities for developing teacher well-being in a general education school.
No full textBy the end of the COVID-19 pandemic, some teachers felt so exhausted that they reached a breaking point and decided to change their profession because they felt unwell as teachers (Doan et al., 2023; Marshall et al., 2022). The Ministry of Education, Science and Sport of the Republic of Lithuania (2023) acknowledges that there is a shortage of qualified teachers in Lithuania. It is argued that countries facing teacher shortages should make the creation of teacher well-being a priority in education (Bertieaux et al., 2024; Doan et al., 2023; See et al., 2024). The object of this master’s thesis is the development of opportunities to enhance teacher well-being. The study aims to reveal the opportunities for developing teacher well-being in a general education school. To achieve this aim, the following objectives were formulated: to justify the theoretical assumptions of teacher well-being in general education schools; to substantiate the methodology of researching teacher well-being promotion opportunities; and to identify these opportunities from the perspectives of both teachers and school leaders. The research methods applied include scientific literature analysis, document analysis, semi-structured interviews, and qualitative content analysis using the MAXQDA Analytics Pro 24 software. The literature review revealed that teacher well-being is an individual state, related to one's professional experience, encompassing at least several dimensions such as cognitive, subjective, social, physical, and psychological. A theoretical model was developed, illustrating the interaction between factors determining teacher well-being and the opportunities that support its development in the school context. The study shows that personal factors influence well-being, and thus, in order to enhance it, teachers should take advantage of available opportunities, such as professional development and seeking relaxation methods. Furthermore, environmental factors – such as the presence of supportive students, their parents, and a safe physical environment – also play a role. Improving well-being should also be linked with fostering a positive school climate through encouraging collaboration and motivating professional growth. Teacher well-being is also influenced by educational policy and broader societal context. Policymakers are advised to listen more to teachers’ opinions, provide teachers with more opportunities to care for their health, while society as a whole should show greater support and respect. The analysis of interviews with teachers and school principals confirmed that teacher well-being is a multidimensional phenomenon composed of various interrelated components. The findings indicate that teacher well-being is strongly tied to the personal efforts of the teacher. A teacher who is positively minded and confident is more likely to benefit from the support of those around them. The role of school administration is also emphasized, e.g.: offering help in solving problems, organizing individual consultations, reducing bureaucracy and work-related demands, placing trust in teachers, and providing autonomy. To promote a positive school climate, schools are encouraged to officially document climate-related goals, organize informal community-building activities. Students also play an important role in teacher well-being: their engagement in classroom activities, adherence to agreements, respectful attitudes, and empathy are essential. Teachers should organize activities that strengthen their relationship with students. Likewise, the involvement of students' parents matters, e.g.: cooperation, and mutual respect are fundamental. At the same time, teachers should actively encourage parents to take part in the educational process. The role of educational policymakers includes consulting teachers before implementing reforms and offering support afterward. They should promote teacher health, ensure more autonomy in the teaching process, provide fair remuneration, and enhance teacher evaluation systems. Society should express respect toward teachers, increase the prestige of the teaching profession – particularly with the help of media – and highlight the positive aspects of teaching. This master’s thesis consists of an introduction, three main parts (a review of the scientific literature, methodological justification, and empirical research analysis and summary), followed by conclusions, recommendations, and appendices. The thesis comprises 105 pages, 30 figures, 3 tables, and 7 appendices
Pjezoelektrinės kompozitinės medžiagos beta fazės polivinilfluorido pagrindu kūrimas biomechaniniams jutiklaims.
No full textThis thesis aims to develop a PVDF-based piezoelectric composite material with a cybersecurity model. The objectives include the synthesis of PVDF by incorporating HA, GO, and AgNO3 nanoparticles to create a piezoelectric composite characterized by β-phase transformation. The study also aims to evaluate the influence of HA, GO, and AgNO3 nanoparticles and their different compositions on the electrical, mechanical, and morphological properties of the piezoelectric composite. The study also aims to investigate the influence of GO on the piezoelectric, electrical, and morphological properties of the PVDF-based composite for sensing functional elements. The main focus is on the fabrication process of the functional element composed of PVDF, HA, GO, and AgNO3. The solvent casting method and the non-toxic solvent DMSO were chosen to fabricate the functional element. This fabrication method and materials were chosen to increase the beta phase, which is very important for data protection and piezoelectric properties. The results of the composites with PVDF, HA, GO, and AgNO3 are presented. The properties of materials are determined experimentally by measuring SEM, FTIR, vibration measurements, electrical characteristics, piezoelectric properties, hydrophilicity, roughness, and other characteristics
Benzothiazole-based arylamines as hole transporting materials for perovskite solar cells /
No full textThe performance of perovskite solar cells (PSCs) is partially dependent on the properties of the hole transporting material (HTM) used. Here, we present the synthesis and study of novel benzothiazole-based arylamine HTMs. The compounds are thermally stable, decomposing at temperatures >350 °C, and exist in amorphous states. The ionization potential values of the HTMs are between 5.26-5.62 eV, which are optimal with respect to the valence band energy of perovskite (∼5.7 eV). PSCs employing the best performing HTM resulted in a power conversion efficiency (PCE) of 20.74% with a fill factor (FF) of 77.6%. With this we present donor-π-bridge-acceptor type-strategy as an effective method to increase charge transport properties of benzothiazole-based small molecule HTMs that are obtained in high yield via a simple Knoevenagel condensation reaction resulting in improved performance of the hole transporting layer in PSCs
Improving multi-class classification for recognition of the prioritized classes using the analytic hierarchy process /
No full textMachine learning (ML) algorithms are widely used in various fields, including cyber threat intelligence (CTI), financial technology (Fintech), and intrusion detection systems (IDSs). They automate security alert data analysis, enhancing attack detection, incident response, and threat mitigation. Fintech is particularly vulnerable to cyber-attacks and cyber espionage due to its data-centric nature. Because of this, it is essential to give priority to the classification of cyber-attacks to accomplish the most crucial attack detection. Improving ML models for superior prioritized recognition requires a comprehensive strategy that includes data preprocessing, enhancement, algorithm refinement, and customized assessment. To improve cyber-attack detection in the Fintech, CTI, and IDS sectors, it is necessary to develop an ML model that better recognizes the prioritized classes, thereby enhancing security against important types of threats. This research introduces adaptive incremental learning, which enables ML models to keep learning new information by looking at changing data from a data stream, improving their ability to accurately identify types of cyber-attacks with high priority. The Analytical Hierarchy Process (AHP) is suggested to help make the best decision by evaluating model performance based on prioritized classes using real multi-class datasets instead of artificially improved ones. The findings demonstrate that the ML model improved its ability to identify prioritized classes of cyber-attacks utilizing the ToN_IoT network dataset. The recall value for the “injection” class rose from 59.5% to 61.8%, the recall for the “password” class increased from 86.7% to 88.6%, and the recall for the “ransomware” class improved from 0% to 23.6%
Comparison of LLM few-shot vs. synthetic data approaches for Lithuanian event extraction /
No full textPerspectives on the application of social innovations in the social services sector /
No full textRapid societal changes drive the integration of social innovations into the social services sector. Demographic shifts, population aging, increasing social inequality, and ongoing challenges related to service accessibility and sustainability necessitate innovative solutions to enhance the efficiency and effectiveness of social services. The challenges of globalization further encourage a shift from traditional service delivery models. Social innovations, characterized by novel operational methods, collaborative governance models, and technological advancements, provide opportunities to improve service quality, accessibility, and long-term sustainability. These innovations not only address pressing social issues but also play a crucial role in strengthening community resilience, reducing social exclusion, and fostering inclusive development. Despite the potential of social innovations, their implementation faces numerous obstacles, including financial constraints, bureaucratic inertia, institutional barriers, and the complexities of adopting technological solutions. The aim of this study is to assess the role of social innovations in the social services sector, identify key barriers to their implementation, and propose strategies to overcome these challenges. The study employs a qualitative research methodology, utilizing interviews and content analysis to provide a comprehensive examination of social innovation practices across various social service sector contexts. The findings reveal that integrating innovative solutions not only enhances the efficiency of social services but also drives broader social transformations—strengthening local communities, reducing social inequality, and increasing the resilience of social service systems in times of crisis. The study highlights the importance of interdisciplinary collaboration, continuous professional development for social service practitioners, and the creation of a more flexible institutional environment to support the expansion of innovations