Welcome to Academic Digital Repository
OpenAccess@KU is an academic, open-access repository. It aims to collect, preserve and make Kastamonu University’s scientific output available online, without any or the least financial, legal or technical restrictions, in order to increase the impact and the visibility of the institution and its authors. It was established in 2010 to support the dissemination of knowledge produced by the University members to the wider community both locally and globally.
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Navigating school science fairs in the artificial intelligence age: a local fair transformed
(2025.01.01) Kaya, G.; Sardag, M.; Cakmakci, G.
BackgroundThe integration of artificial intelligence and digital platforms has significantly transformed educational practices, particularly in response to the COVID-19 pandemic. Science fairs, a vital aspect of STEM education, have evolved from traditional in-person events to virtual formats. These virtual science fairs offer unique opportunities for broader accessibility and cost-efficiency while maintaining the integrity of science communication and student engagement.PurposeThis study explores the transition of science fairs to virtual environments, examining their impact on students, teachers, and the overall educational experience.SampleThe study involved eight volunteer STEM teachers (four female, four male) from various secondary schools in Turkey. These teachers had prior experience with science fairs and participated in semi-structured interviews to share their experiences with virtual science fairs.Design and methodsA qualitative case study approach was employed to explore the experiences of teachers and the implementation of virtual science fairs. Data were collected through semi-structured interviews and analyzed to identify recurring themes related to the advantages, disadvantages, contributions to teachers and students, and the interaction dimensions of virtual fairs.ResultsThe findings revealed that virtual science fairs provide significant advantages, such as wide participation, economic efficiency, and the ability to transcend geographic boundaries. However, they also present challenges, including technical difficulties and reduced sensory engagement. Teachers noted that virtual fairs enhanced their awareness of using digital platforms for educational purposes, while students reported increased motivation, self-confidence, and a sense of connection to the real world through these virtual experiences.ConclusionVirtual science fairs represent a viable alternative to traditional in-person events, offering broader accessibility and fostering student engagement in STEM education. While they present certain challenges, the benefits of virtual fairs in terms of inclusivity, cost-efficiency, and educational impact suggest their continued relevance and potential for future educational practices.
Efficiency Enhancement of GaN/InN-Based Solar Cells through Doping with Si, Zn, Ag Elements: A Physico-Chemical Study of Nanosurface by First-Principles Calculation
(2025.01.01) Mollaamin, F.
As applied materials for storage energy in solar cells, hetero clusters of GaN, InN, GaInN, GaInSiN, GaInZnN, GaInAgN can attract considerable attention in materials science. A comprehensive investigation on energy grabbing by GaN, InN, GaInN, GaInSiN, GaInZnN, GaInAgN was carried out including using DFT computations at the CAM-B3LYP-D3/6-311+G(d,p) level of theory. Electromagnetic and thermodynamic properties of GaN, InN, GaInN, GaInSiN, GaInZnN, GaInAgN hetero clusters have been evaluated. The hypothesis of the energy adsorption phenomenon was confirmed by density distributions of CDD, PDOS, and ESP for GaN, InN, GaInN, GaInSiN, GaInZnN, GaInAgN hetero clusters. The two hetero clusters of GaInZnN and GaInAgN with the fluctuations of In, Ga, N and transition metals of Zn, Ag have indicated the same sensitivity graph of electric potential via charge distribution with \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$R_{{{\text{Zn}}/{\text{Ag}} - {\text{GaInN}}}}<^>{2}$$\end{document} = 0.9998. Therefore, it can be considered that zinc and silver atoms in the functionalized GaInZnN and GaInAgN may have more effective sensitivity for admitting the electrons in the status of energy adsorption mechanism. Furthermore, GaInAgN is potentially advantageous for certain high-frequency applications requiring solar cells for energy storage. The advantages of silver over indium gallium nitride include its higher electron and hole mobility, allowing silver doping devices to operate at higher frequencies than silicon and zinc doping devices. As a matter of fact, it can be observed that doped hetero clusters of GaInZnN and GaInAgN might ameliorate the capability of GaInN in solar cells for energy storage.
Triphenylphosphine-functionalized hyper-crosslinked polymers for efficient hydrogen generation via sodium borohydride methanolysis
(2025.01.01) Gokkus, K.; Ozbal, A.; Gür, M.; Akalin, S.A.; Sebli, H.; Bütün, V.
Four novel hyper-crosslinked polymers (HCP-1 to HCP-4) were synthesized via Friedel-Crafts alkylation using 4,4 '-bis(chloromethyl)-1,1 '-biphenyl as the crosslinker and various aromatic monomers including triphenylphosphine (TPP). These polymers were designed as metal-free catalysts for hydrogen generation via sodium borohydride methanolysis. Comprehensive characterization using FT-IR, XPS, BET, TGA, SEM, and zeta potential analyses confirmed that the materials possess thermally stable, porous networks with irregular morphologies and distinct surface charges. Under practical conditions, HCP-3 exhibited the highest catalytic activity with a hydrogen generation rate of 9857 mL H2 min- 1 g- 1 at 303.15 K and the lowest activation energy (Ea = 32.0 kJ mol-1). At elevated temperature (333.15 K), HCP-2 achieved the highest activity (37,200 mL H2 min- 1 g- 1), reflecting the strong influence of temperature on performance trends. Despite not having the highest surface area or pore volume, the superior activity of HCP-3 at 303.15 K highlights the decisive roles of microporous architecture, electrostatic surface characteristics, and heteroatom functionality. Zeta potential analysis revealed significant reductions in surface charge after reaction, particularly for HCP-3, suggesting strong electrostatic interactions with BH4- ions. XPS data further confirmed the successful incorporation of TPP and heteroaromatic units, correlating with enhanced catalytic efficiency. Overall, the findings underscore a surface-mediated mechanism where both charge-assisted hydride attraction and structural topology govern hydrogen evolution. The metal-free and reusable nature of these catalysts supports their potential in sustainable hydrogen technologies.
Exercise-induced ventricular arrhythmias and subclinical ischemia risk in firefighters: exploratory results from a pilot study
(2025.01.01) Demiralp, N.; Akyel, S.; Koç, H.; Öztürk, A.
AimThis pilot study aimed to systematically evaluate exercise-induced electrocardiographic (ECG) responses in professional firefighters and to explore the association between premature ventricular complexes (PVCs) and myocardial ischemia in this high-risk occupational group.MethodThis pilot cross-sectional study enrolled 21 male firefighters (mean age 43.4 +/- 7.18 years) from a single municipal fire department. Participants underwent comprehensive cardiovascular assessment including anthropometric measurements, biochemical analyses (lipid profile, testosterone), submaximal exercise testing (Bruce protocol), and 24-h Holter ECG monitoring. Statistical analyses included Mann-Whitney U tests and effect size calculations.ResultsNo exercise-induced ST-segment changes indicative of myocardial ischemia were observed. However, PVCs were detected in 33% of participants (7/21), with exercise testing revealing 18 simple and 2 multiform PVCs, while Holter monitoring recorded 25 simple and 1 multiform PVC. PVC-positive firefighters were significantly older (median 49 vs. 40 years, p = 0.019, r = 0.514). Mean exercise capacity was 12.45 METs, with 81% achieving moderate fitness levels. Post-exercise heart rate recovery (HRR1: 24 +/- 11.5 bpm; HRR2: 35.4 +/- 11.5 bpm) showed normal patterns.ConclusionThe findings of this pilot study indicate the need for larger-scale investigations, supported by advanced diagnostic modalities, to clarify the clinical relevance of exercise-induced premature ventricular complexes (PVCs) in firefighters. Although no ischemic changes were observed, the presence of subclinical coronary artery disease cannot be definitively excluded. These results provide a meaningful preliminary foundation for developing targeted screening approaches to improve early cardiovascular risk detection in high-physical-demand occupational groups.
Impact of nutritional status in sarcoidosis patients
(2025) Tunç, Ş.; Yıldız, P.; Sungur, M.A.
Background and aim: Sarcoidosis is a systemic granulomatous disease of unknown etiology, with fatigue being one of the most common symptoms. The cause is still under investigation. Factors such as reduced lung function, respiratory muscle weakness, physical deconditioning, corticosteroid-induced myopathy may cause fatigue. Nutritional status of patients is becoming increasingly important in respiratory diseases. This study aimed to investigate the effect of nutritional assessment on peripheral and respiratory muscle strength, as well as exercise capacity in sarcoidosis patients.
Methods: This prospective, case-controlled study included 31 sarcoidosis patients not receiving systemic steroid therapy and 24 age- and sex-matched healthy controls. Participants were tested for functional exercise capacity using the 6-minute walk test (6MWT), respiratory muscle strength using maximum inspiratory (MIP) and expiratory pressures (MEP), peripheral muscle strength using handgrip dynamometry and lung function tests. Nutritional status was assessed using the Mini Nutritional Assessment (MNA) questionnaire and body composition analysis by bioelectrical impedance.
Results: Despite similar lung function and respiratory muscle strength, sarcoidosis patients showed significantly lower 6MWT distances compared with controls. Sarcoidosis patients had higher body mass index (BMI) and fat mass, while lean mass, smooth muscle mass, skeletal muscle mass, fluid weight and peripheral muscle strength were similar in the patient group and control group. There was no significant difference in MIP, MEP and expected percentage values in sarcoidosis patients compared to the control group. Positive correlations were observed between MIP, MEP and lean body mass, while fat mass was negatively correlated with peak expiratory flow (PEF).
Conclusions: This study highlights the need for individualized interventions, including lifestyle modifications, nutrition, and physical rehabilitation, in sarcoidosis-related fatigue. In our study, BMI and fat weight were significantly higher in sarcoidosis patients. In light of this, further research is needed to investigate the impact of adiposity-related inflammation on sarcoidosis progression and outcomes.