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Predicting daily net ecosystem production in shallow lakes from dissolved oxygen saturation levels: a pan-European mesocosm experiment and modelling approach
No full textNet ecosystem production (NEP) is an important indicator of lake ecosystem function and integrity. An earlier study, restricted to one geographical region, indicated that oxygen saturation levels (DO%) might be used to predict daily NEP in shallow lakes. To test the generality of the method, we used DO% data collected in a standardised pan-European mesocosm experiment with contrasting trophic states and water levels covering a large climate gradient (from Sweden to Turkey). We corroborated these data with process-based DO simulations. The NEP ~ DO% relation depended on factors influencing gas transfer: water depth and wind. The NEP ~ DO% relation per volume became weaker with increasing depth (1–2 m) but was independent of depth when area based. Simulations indicated that the marginalisation of the depth was sensitive to wind conditions. Trophic status, temperature and light showed no or only marginal (climate zone) effects (experimental data), while the simulations indicated influence of those factors under particular wind–depth conditions. We confirmed that when considering also wind and depth effects, midday DO% potentially provides reliable estimates of daily NEP. Therefore, historical monitoring data of DO% might be used to estimate NEP, and process-based oxygen models may be valuable tool therein. We encourage further tests
Evaluation of methodological and analytical approaches in assessing intra-individual serum progesterone variability on frozen embryo transfer day across hormone replacement therapy cycles
No full textA robust optimization model to design an IoT-based sustainable supply chain network with flexibility
No full textSupply chain network design is one of the most important issues in today’s competitive environment. Moreover, the ratio of transportation costs to the income of manufacturing companies has increased significantly. In this regard, strategic decisions, as well as tactical decisions making, are of concern for supply chain network design. In this research, a flexible, sustainable, multi-product, multi-period, and Internet-of-Things (IoT)-based supply chain network with an integrated forward/reverse logistics system is configured where the actors are suppliers, producers, distribution centers, first- and second-stage customers, repair/disassembly centers, recycling centers, and disposal centers. In order to create flexibility in this supply chain, it is possible to dispatch directly to customers from distribution centers or manufacturing plants. For direct shipping, the application IoT system is taken into account in the transportation system to make them able to manage direct and indirect delivery at the same time. The options and considerations are then incorporated into a Multi-Objective Mixed-Integer Linear Programming model to formulate the problem which is then converted into a single-objective model using Goal Programming (GP) method. Moreover, in order to deal with uncertainty in the demand parameter, robust optimization approach is applied. The obtained results from a numerical example reveal that the proposed model is able to optimally design the supply chain network whose robustness is highly dependent on the budgets of uncertainty whereas up to 213.528% increase in the GP objective function is observed
Development of stable and porous Ag2O-loaded hydroxyapatite nanocomposites for enriched photocatalytic degradation of Rhodamine B under visible light
No full textA simple and inexpensive process from natural phosphate in the presence of Ag+ ions was used to develop Ag2O-loaded hydroxyapatite nanocomposites. The structural and textural characterization of the nanocomposites suggests that the Ag2O nanoparticles are well dispersed on the hydroxyapatite (HAp). The prepared nanocomposites show efficient Rhodamine B (RhB) dye photocatalytic degradation in water under visible and UV–visible light irradiation. Meanwhile, the photocorrosion instability and photosensitivity disadvantages of Ag2O could be largely solved when loaded into hydroxyapatite, which works as an electron sink receiving the electrons photogenerated by Ag2O and fixes the by-products onto the porous matrix. These composites demonstrate a practical potential for the remediation of toxic water contamination under various irradiation sources
Seismic scenario simulation and ANN-based ground motion model development on the North Tabriz Fault in Northwest Iran
No full textEarthquakes pose significant seismic hazards in urban regions, often causing extensive damage to the built environment. In regions lacking robust seismic monitoring networks or sufficient data from historical events, ground motion simulations are crucial for assessing potential earthquake impacts. Yet, validating these simulations is challenging, leading to notable predictive uncertainty. This study aims to simulate four scenario earthquakes with moment magnitudes of 6.8, 7.1, 7.4, and 7.7 in Iran, specifically investigating variations in fault plane rupture and earthquake hypocenter. The North Tabriz Fault (NTF), located within the seismic gap in northwest Iran, is selected as the case study due to the lack of well-recorded ground motions from severe earthquakes, despite historical evidence of large-magnitude events. Simulations are conducted using a stochastic finite-fault ground motion simulation methodology with a dynamic corner frequency. Validation of the simulations is performed by comparing estimated peak ground motions and pseudo-spectral ordinates with existing ground motion models (GMMs), supplemented by inter-period correlation analysis. Simulation results reveal high hazard levels, especially in the northeastern area near the fault plane. Intensity maps in terms of the Modified Mercalli Intensity (MMI) scale underscore the urgency for comprehensive preparedness measures. Finally, a region-specific GMM is developed using Artificial Neural Networks (ANN) to predict peak ground motion parameters with an online platform accessible to end-users
Constructions in dynamic geometry environments: How valid are they?
No full textThe purposes of this study are to investigate to what extent prospective middle school mathematics teachers can offer valid solutions for geometric construction problems in dynamic geometry environments, how we can characterise whether their solutions are valid or invalid, and the nature of their solutions. Data were collected from prospective middle school mathematics teachers through four geometric construction activities. By considering the data, the scope of the drag test and compatibility criterion offered in the literature, and the extra cases regarding the drag test, a three-phase diagram was proposed to characterise the validity of solutions to geometric construction problems in dynamic geometry environments. In the evaluation based on the diagram, it was found that the group could offer at least one valid solution, leading them to geometric construction in each activity. Some solutions were coded as invalid based on the diagram, although the group declared them valid
Investigating the early years of STEM education reform in Türkiye from an equity standpoint
No full textDisadvantaged students have struggled to find equal opportunities in STEM; thus, it is critical to challenge global society’s structures so that all students have equal opportunities to learn and become proficient in STEM subjects. To even begin to address STEM equality issues, action plans and solutions must address all tiers of society. However, equity in STEM education reform has received little attention in Türkiye. The purpose of this study is to examine the first years of STEM education reform in Türkiye from the standpoint of equity. The research used a single case with embedded units. The embedded units were seven regions of Türkiye, each with its own set of social, economic, and cultural circumstances. Twenty-one teachers and school principals from different regions of Türkiye participated in the study. Data were gathered through semi-structured interviews and published documents. The collected data were coded based on the dimensions of the theoretical framework, which was built by combining Bybee’s (2013) framework for analyzing STEM education reform initiatives and Gutierrez’s (2009) framework for teaching for equity. The findings highlighted the equity and justice challenges and opportunities that STEM education reform entailed. While participants recognized the potential of STEM education initiatives to promote equity in classrooms, particularly in terms of identity and power, the study’s findings revealed that the reform’s implementation favored schools serving students from higher socioeconomic backgrounds, widening the opportunity gap between students from different backgrounds
OptCD: Optimizing Continuous Development
No full textDevelopers may mistakenly configure their continuous development (CD) workflow to generate files, such as code coverage reports, that are not used during the CD workflow nor uploaded afterwards. Generating these unused files slows down the CD process and is a waste of time and resources. We present OptCD, a tool that automatically identifies unused files that are generated or modified, but are never used or uploaded. OptCD then uses the identified unused files to find directories where all underlying files are unused. OptCD operates on Mavenbased Java projects that use GitHub Actions as their CD service. OptCD pinpoints the Maven plugins (the process that performs build tasks for Maven) that generated a given directory of unused files by analyzing which plugins were running at the time the files were generated. Finally, OptCD leverages Gemini, a large language model, to generate a fix for the CD configuration file to stop generating the directory of unused files. Compared to our prior work, we (1) streamline and simplify the process to use OptCD (e.g., reducing five nontrivial manual steps to just one automated step) and (2) conduct an extensive evaluation of OptCD on 89 new projects compared to just 22 from our prior work. OptCD finds that 59.6% of the new projects generate at least one directory of unused files, and OptCD's fixes save an average of 9.3% of Maven's runtime in these projects. A video demo of OptCD is available on our website
Zinc Chalcogenide Based Shell Layers for Colloidal Quantum Wells
No full textColloidal quantum wells, also known as colloidal nanoplatelets (NPLs), have emerged as a promising class of materials for light-emitting devices (LEDs). However, the most widely studied core/shell NPLs, which rely on cadmium-based shell layers, face challenges due to toxicity concerns and improper charge confinement. To address these limitations, a new synthetic approach is presented that enables the controlled growth of zinc chalcogenide-based shell layers on NPLs. The synthesized CdSe/ZnSe core/shell NPLs exhibit emission between 615 and 630 nm, with a moderate photoluminescence quantum yield (PL-QY) of 40–50%. It is also demonstrated that the lateral dimensions of the CdSe core NPLs significantly affect the optical properties of the core/shell heterostructures, with smaller lateral dimensions resulting in narrower emission linewidths as low as 20 nm. Further passivation of these core/shell NPLs with an additional ZnS shell layer significantly increases the PL-QY up to 80–90%. Finally, the device performance of these two core/shell NPLs is investigated by fabricating solution-processed LEDs. With LEDs incorporating CdSe/ZnSe/ZnS core/multi-shell NPLs as the active light-emitting layer, an external quantum efficiency (EQE) of 3.82% and a maximum brightness of 6477 cd m−2 is obtained. These findings underscore the significant potential of zinc chalcogenide-based shell layers in advancing colloidal NPLs toward high-performance light-emitting devices
Performance and Modelling of PTFE and PTFE plus PANI-based Electrode Modifications in Cylindrical H-Type Microbial Fuel Cells
No full textMicrobial fuel cells (MFCs) are advanced bioelectrochemical systems that simultaneously treat wastewater and generate electricity using electroactive bacteria as biocatalysts. In this study, different anode and cathode electrodes were modified using PTFE-based and PTFE+Polyaniline (PANI)-based binders combined with activated carbon and expandable graphite, and their effects on MFC performance were evaluated. The maximum power density values were measured at 85,07 mW/m2 for the PTFE-based electrode and 91,86 mW/m2 for the PTFE+PANI-based electrode. The chemical oxygen demand (COD) removal efficiencies were 80,52% and 80,17% and coulombic efficiencies 2,07% and 2% for the PTFE-based and PTFE+PANI-based electrodes, respectively. Additionally, full factorial design optimization was conducted using design expert 7.0.0, and the modeling results were successfully validated. Based on the findings, it can be concluded that the PTFE-based electrode enhances power generation in cylindrical H-type MFCs by improving electron transfer and biofilm formation