哈兰大学

In this study, the gamma and X-ray radiation attenuation properties of B4C-TiB2 reference ceramics and those reinforced with 1, 2, and 3 vol% graphene nanoplatelets (GNP) were systematically investigated. The composites were fabricated via Spark Plasma Sintering (SPS), enabling rapid densification and controlled microstructural evolution. B4C is known for its strong thermal neutron absorption due to its high 10B content. In addition, it contributes to gamma radiation attenuation through photon absorption and scattering interactions. The incorporation of TiB2 and GNPs into B4C enhances the composite density thereby increasing the photon interaction probability and improving the overall gamma shielding performance. Radiation attenuation measurements of the composites were conducted using 0.356 MeV (133Ba), 0.662 MeV (137Cs), and 1.173 MeV (60Co) sources, and diagnostic X-ray sources (50-110 kVp). Gamma and X-ray attenuation coefficients were independently calculated through MCNP6.2 Monte Carlo simulations to validate the experimental results. The close agreement between simulated and measured values demonstrates the reliability of the computational methodology and its consistency with established theoretical models of photon interaction cross sections. This consistency further supports the applicability of the approach for accurate evaluation and comparative analysis of photon attenuation performance in composite materials. In this study, key photon interaction parameters including the half value layer (HVL), tenth value layer (TVL), mean free path (MFP), effective atomic number (Zeff), and effective electron density (Neff) were computed. The results indicate that these parameters are significantly dependent on both the photon energy and the chemical composition of the examined composites. Both MCNP and experimental results show that the B4C-TiB2-GNP composites have linear attenuation coefficients (μ) ranging from 0.1468 to 0.2498 cm−1, with the sample with 1 vol% GNP (BT1G) exhibits the highest performance, reaching 0.2498 cm−1 for 133Ba. The results reveal that among all investigated samples, the BT1G composite exhibits the highest shielding efficiency in radiation conditions. GNP-reinforced B4C-TiB2 composites, may serve as a potential alternative to reduce the use of lead in gamma radiation protection.

Abstract The recycling of construction and demolition waste in concrete composites is becoming increasingly significant for mitigating environmental impacts and enhancing resource efficiency while also providing accessible, cost-effective, and beneficial materials for sustainable construction. This study examines the synergistic effects of composite waste powders on the microstructural, mechanical, thermodurability, and sustainability characteristics of the concrete utilizing multibinder systems, which include portland cement (PC), ceramic waste powder (CWP), marble waste powder (MWP) and red brick waste powder (RBWP). Twenty-seven concrete mixtures were formulated, adhering to a consistent water-to-binder ratio of 0.38 and a total binder content of 450 kg / m 3 . The control contained only PC as the binder, whereas the other mixtures included binary, ternary, and quaternary cementitious waste blends of PC–CWP–MWP–RBWP to assess their collective impact on the concrete performance. Additionally, the multicriteria decision-making (MCDM) and desirability function optimization were employed to ascertain the ideal concrete mixture, guaranteeing a balance among the mechanical performance, durability, and sustainability. The findings of the experimental study indicated that incorporating up to 10% CWP or MWP enhanced the compressive and flexural strengths owing to the pozzolanic and filler effects; however, elevated RBWP concentration markedly diminished the strength. The thermal conductivity improved by as much as 36.9% in quaternary mixtures, signifying improved insulation. The sorptivity index decreased by 11.9% with CWP and MWP, but it increased by 31.7% with RBWP due to its higher porosity. The carbon footprint ( CO 2 emissions) decreased about 13.9% in binary mixtures and up to 33.1% in quaternary systems, with CWP demonstrating the most significant effect. The MCDM suggests that a concrete mixture with 20% CWP is the best concrete mix since it provides the highest overall score with 0.621 based on their strength, durability, thermal conductivity, and sustainability properties.

Aim This study was conducted to examine the mediating role of perceived social support in the relationship between perceived stress and sleep disturbances in mothers of children with food allergies. Method This study was conducted as a descriptive-cross-sectional study. “DASS-21 Scale,” “Basic Scale of Insomnia Complaints and Sleep Quality,” and “Multidimensional Scale of Perceived Social Support” were used to collect the research data. The study included 89 mothers. A Structural Equation Model (SEM) was established, and the mediating model was analyzed by using the PROCESS macro (Model 3). Results The results demonstrated that maternal perceived stress significantly and negatively predicted perceived social support scores (β = −0.258, p = 0.012), while it positively predicted insomnia complaints and significantly worsened sleep quality (β = 0.813, p < 0.001). It was found that mothers' perceived levels of social support negatively predicted insomnia and sleep quality (β1 = −0.205; p < 0.001). According to the results of the model, mothers' perceived social support scores explained 36.6% of the variance in their stress scores (R2 = 0.366). Conclusion It was found that social support plays a mediating role in the relationship between the stress perceived by mothers and insomnia and sleep quality. Practice implications During routine clinical check-ups for children diagnosed with food allergies, not only the child's physical health but also the mother's psychological state should be assessed. Considering that perceived stress in mothers directly and strongly affects sleep quality, pediatric nurses and physicians should be encouraged to use brief stress and sleep screening tools.

The frequency and severity of floods and droughts have increased due to climate change, along with mismanagement, and increasing demand for water resources due to population growth. Due to this increasing demand, dependence on groundwater resources has been needed unprecedentedly. In addition, overuse and unsustainable irrigation have severely stressed groundwater, which is a limited resource. This study has been used multi-criteria decision-making methods to determine the spatio-temporal variation of groundwater potential zones for ensuring effective groundwater management and security. Geographic Information Systems (GIS) and Remote Sensing (RS) technologies are used to integrate 10 thematic layers, i.e., precipitation, soil, geology, elevation, lineament density, slope, drainage density, land use/land cover (LULC), topographic wetness index (TWI), and topographic roughness index (TRI). The groundwater potential areas, with a high spatial resolution of 10 m, were delineated using the Analytic Hierarchy Process (AHP) and Fuzzy Analytic Hierarchy Process (Fuzzy-AHP) in the study area of the Harran Plain, Türkiye. The integrity of the mapped potential zones was authenticated by well measurements and application of the Receiver Operating Characteristic (ROC) analysis, which yielded an Area Under Curve (AUC) value of 72.7

PurposeThis study investigates the impact of transformational school leadership on organizational change, emphasizing the mediating roles of instructional strategy self-efficacy and professional learning while also examining the direct effect of AI anxiety on organizational change. Design/methodology/approachA theoretical model is developed and tested using structural equation modeling based on data collected from 1,000 teachers across 40 schools in 20 provinces within Türkiye's NUTS-1: 12 regions. FindingsThe results reveal that teachers' perceptions of transformational school leadership positively influence instructional strategy self-efficacy, professional learning, and organizational change. Additionally, instructional strategy self-efficacy, professional learning, and AI anxiety are positively linked to organizational change. The mediation analysis highlights the significant role of instructional strategy self-efficacy and professional learning in explaining the relationship between transformational school leadership and organizational change. Originality/valueThis study contributes to the literature on leadership and organizational change by demonstrating the mechanisms through which transformational leadership fosters instructional strategy self-efficacy, professional learning, and adaptation to organizational change. It also extends research on AI anxiety and its influence on educational settings.