WoS İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/394
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Article Citation - WoS: 13Citation - Scopus: 14Unravelling the Moderating Roles of Environmental Regulations on the Impact of Foreign Direct Investment on Environmental Sustainability(Academic Press Ltd- Elsevier Science Ltd, 2025-02) Ehigiamusoe, Kizito Uyi; Chen, Danqing; Dogan, Eyup; Binsaeed, Rima H.In the era of economic globalization, China attracts significant foreign direct investment (FDI) to accelerate economic prosperity. FDI inflows could have ramifications on environmental degradation (ED) despite the enactment of different environmental regulations (ERs) such as market-incentive, command-and-control as well as informal regulations. Though some studies have shown that FDI and ED have significant relationship, the moderating roles of different ERs on the environmental impact of FDI has not been empirically unraveled. This study fills this research gap by analyzing the direct impact of FDI on ED (i.e., carbon dioxide emissions, ecological footprint) using the provincial panel data. Second, it unravels the moderating roles of different ERs on the environmental impact of FDI in the provinces and regions. The results indicate that FDI directly mitigates ED, verifying the pollution halo hypothesis while ERs directly alleviate ED in China. However, the interaction between FDI and ERs do not alleviate ED in China albeit regional heterogeneity exist. The economic implication is that FDI is not a channel through which ERs enhance environmental sustainability in China. This study recommends some policy options arising from the findings.Article Citation - WoS: 9Citation - Scopus: 8Stress and Damage Distribution Analysis of Steel Reinforced Geopolymer Concrete Beams: Finite Element Method and Experimental Comparison Under Varying Design Parameters(Elsevier, 2025-06) Ozbayrak, Ahmet; Kucukgoncu, Hurmet; Aslanbay, Huseyin Hilmi; Aslanbay, Yuksel GulGeopolymer concrete (GPC) is a sustainable and eco-friendly alternative to ordinary Portland cement-based concrete (OPC). However, its application in reinforced concrete structures remains limited due to insufficient research on structural performance. This study examines the effects of tensile reinforcement ratio, sodium silicate/sodium hydroxide ratio, and curing method on GPCreinforced concrete (GPC-RC) beams. Experimental and numerical bending tests were performed on GPC and OPC beams with similar tensile reinforcement and strength properties. Load- displacement and moment-curvature relationships were obtained and compared, while stress and stiffness behaviors were analyzed numerically. The results show that curing methods and reinforcement ratios significantly influence GPC beam behavior. In GPC samples, numerical and experimental displacement and load values differed by approximately 10 % at both yield and ultimate points. For OPC, these differences were 35 % and 14 % at the yield point and 17 % and 25 % at the ultimate point. GPC exhibited distinct stress and damage distribution characteristics compared to OPC. The finite element models were statistically validated, confirming their consistency with experimental results. These findings contribute to the understanding of GPC's structural behavior and provide guidance for its design and optimization in reinforced concrete applications.Article Citation - WoS: 2Citation - Scopus: 2Rural Feet Voting of Leisure Explorers(Wiley, 2025-01) Turk, Umut; Toger, Marina; Osth, John; Kourtit, Karima; Nijkamp, PeterIn the COVID-19 period, spatial leisure behavior, often driven by the desire to escape urban life, reflected health and environmental concerns. This study examines how pandemic-induced spatial motives and changes impacted disparities in leisure mobility, specifically urban-to-rural tourism, in Sweden. Analyzing pre-pandemic, during pandemic, and post-pandemic periods, using anonymized mobile phone and socioeconomic data, the paper explores urban-rural leisure mobility variations. Despite a decline in professional geographical mobility, mainly of people in affluent urban areas, due to remote work, the spatial leisure activities remained rather stable? Our findings, based on a negative binomial regression analysis, reveal also exacerbated socioeconomic segregation in recreational trips. The disruption in mobility accessibility due to COVID-19 appears to amplify existing socioeconomic disparities, notably in urban-to-rural leisure travel. Our research sheds new light on the widening gap in geographical leisure activities, emphasizing the need for equitable access to nonurban destinations.Article Citation - WoS: 6Citation - Scopus: 6Production of High-Grade Antimony Oxide From Smelter Slag via Leaching and Hydrolysis Process(Elsevier, 2025-02) Ibrahim, Ahmedaljaali Ibrahim Idrees; Aboelgamel, Muhammed; Soylu, Kartal Kaan; Top, Soner; Kursunoglu, Sait; Altiner, Mahmut; Ibrahim Idrees Ibrahim, Ahmedaljaali; Kaan Soylu, KartalThis study aimed to investigate the recovery of antimony (Sb) from slag generated in an antimony smelting plant using leaching followed by hydrolysis processes. The leaching behaviors of rare earth elements (REEs) were also examined. The physicochemical properties of the slag were determined using various analytical techniques. The slag (4.12 % Sb) was mainly composed of quartz and minor minerals, including microline, magnetite, heden-bergite, and stibiconite. The Sb types in the slag determined by XPS were found to be in the oxide form. The concentrations of REEs (La, Y, Ce, and Nd) in the slag were 169.21 g/t. Preliminary leaching experiment results indicate that (i) HCl was selected rather than other acids due to its high extraction ability on the Sb from the slag, (ii) a sample with a d50 of <25 mu m should be used, (iii) the slurry should be mixed at 300 rpm. In the following leaching tests, the effects of leaching parameters (HCl acid concentration, amount of tartaric acid, solid-to-liquid ratio, reaction temperature, and time) on the extraction rates of Sb, impurities, and REEs were investigated. At the best leaching conditions (HCl: 8 M, amount of tartaric acid: 1 g/L, stirring speed: 300 rpm, reaction tem-perature: 75 C-degrees, and time: 180 min), the extraction rates of Sb from the slag were determined to be 91.19 %, but the extraction rates of REEs were measured to be <= 50 %. The activation energy (Ea) for Sb leaching was found to be 46.75 kJ/mol, indicating that the reaction was governed by the chemically controlled mechanism. In particular, it was understood from the additional experimental results that the leaching procedure should be carried out for 20 h to extract La with an extraction rate of >90 %. However, the extraction rate of Sb was negligible in extended times. It was determined that using tartaric acid positively affected La's leaching mech-anism, and the required leaching time for La decreased to 180 min from 20 h with the increase of tartaric acid from 1 g/L to 6 g/L. Hydrolysis tests were conducted using the Taguchi approach (L32, 2<^>1 4<^>3). The effects of the alkaline type (NH4OH and NaOH), stirring speed (100, 200, 300, and 400 rpm), temperature (50, 60, 70, and 80 C-degrees), and pH (1.5, 2, 2.5, and 3) on the precipitation of Sb from the PLS were investigated. NH4OH was suggested for use in the hydrolysis test to obtain precipitates with higher purities. The product obtained under the optimal conditions comprised 81.43 % Sb, 16.23 % O, and 2.34 % Fe. The product was identified as antimony oxide by XRDArticle Pressure-Driven Structural Evolution of Amorphous InN(Elsevier, 2025-02) Durandurdu, MuratThrough constant-pressure ab initio simulations, we have uncovered high-pressure phase transformations in amorphous indium nitride for the first time. Our results reveal a distinct two-step progression under compression. Initially, a polyamorphic transition occurs, where the low-density amorphous (LDA) phase transforms into a high-density amorphous (HDA) phase. This HDA structure remains stable in some pressure range and then crystallization initiates, leading to a rocksalt configuration. Upon decompression, the HDA phase reverts to an amorphous network with a slightly higher density and coordination number than the initial LDA state.Article Citation - WoS: 1Citation - Scopus: 1Phase-Separated Amorphous Si2BN: A Computational Study(AIP Publishing, 2025-02-11) Durandurdu, MuratThis study investigates the atomic structure, bonding, and electrical and mechanical properties of amorphous silicon boron nitride (a-Si2BN) using ab initio molecular dynamics simulations. The simulations reveal a distinct phase-separated structure comprising Si-rich and BN-rich domains. BN layers are embedded within the amorphous Si matrix, with only a few bridging atoms linking these regions. The Si-rich region exhibits topological similarities to amorphous silicon, albeit with notable structural distortions. Electronic structure calculations indicate semiconducting behavior with a small bandgap, while mechanical property analysis shows a moderate bulk modulus and Young's modulus, achieving a balance between rigidity and elasticity. These findings position a-Si2BN as a promising material for advanced applications, including flexible electronics, high-temperature semiconductors, and energy storage devices. While the proposed structure is currently hypothetical, its potential experimental realization could open new avenues in material design for emerging technologies.Article Macronutrients in Diets Differentially Affect Gastrointestinal Cytokine and Tight Junction Protein Levels(Univ Putra Malaysia Press, 2025-02-01) Ulutas, M. S.; Cebeci, A.Western diet is known to result in intestinal inflammation and loss of barrier function. In the present work, we investigated whether other macronutrients contribute to inflammation and destabilising barrier function in mice, without using any inflammatory agents, to see the sole effects of dietary intervention. The present work was designed to determine the direct effects of diet on the intestinal barrier function and inflammation, using eight diets that differed on carbohydrate, fat, and fibre ratios for 17 weeks. At the end of the study, a distinct difference in mRNA expressions of cytokines and tight junction proteins was observed between intestinal and colon samples. Small intestinal cytokine expressions showed no difference among different diets, and tight junction protein expressions were only significant for occludin and ZO-1 in high carbohydrate diets. Colon samples had significantly different TNF alpha and IL-6 expressions among diets, especially in high carbohydrate diets. Tight junction protein expressions also differed significantly among diets, and low carbohydrate zero fibre diet had the lowest expression levels compared to the rest of diets. The present work reveals that not only western diet, but also diets high in carbohydrate negatively affect intestinal health, resulting in significant changes in inflammation markers. The role of carbohydrate and fiber contents are also observed in regulating tight junction protein expression. Based on these findings, adjusting macronutrient ratios can be used as a potential approach to help manage intestinal inflammation, though further research is needed. (c) All Rights ReservedArticle Integrating Biological Domain Knowledge With Machine Learning for Identifying Colorectal-Cancer Microbial Enzymes in Metagenomic Data(MDPI, 2025-03-08) Bakir-Gungor, Burcu; Ersoz, Nur Sebnem; Yousef, MalikAdvances in metagenomics have revolutionized our ability to elucidate links between the microbiome and human diseases. Colorectal cancer (CRC), a leading cause of cancer-related mortality worldwide, has been associated with dysbiosis of the gut microbiome. This study aims to develop a method for identifying CRC-associated microbial enzymes by incorporating biological domain knowledge into the feature selection process. Conventional feature selection techniques often evaluate features individually and fail to leverage biological knowledge during metagenomic data analysis. To address this gap, we propose the enzyme commission (EC)-nomenclature-based Grouping-Scoring-Modeling (G-S-M) method, which integrates biological domain knowledge into feature grouping and selection. The proposed method was tested on a CRC-associated metagenomic dataset collected from eight different countries. Community-level relative abundance values of enzymes were considered as features and grouped based on their EC categories to provide biologically informed groupings. Our findings in randomized 10-fold cross-validation experiments imply that glycosidases, CoA-transferases, hydro-lyases, oligo-1,6-glucosidase, crotonobetainyl-CoA hydratase, and citrate CoA-transferase enzymes can be associated with CRC development as part of different molecular pathways. These enzymes are mostly synthesized by Eschericia coli, Salmonella enterica, Klebsiella pneumoniae, Staphylococcus aureus, Streptococcus pneumoniae, and Clostridioides dificile. Comparative evaluation experiments showed that the proposed model consistently outperforms traditional feature selection methods paired with various classifiers.Article Citation - WoS: 3Citation - Scopus: 3Highly Potent New Probiotic Strains From Traditional Turkish Fermented Foods(Springer, 2025-01-21) Yigit, Mehmet Burak; Cebeci, AysunTraditional Turkish fermented foods like boza, pickles, and tarhana are recognized for their nutritional and health benefits, yet the probiotic potential of lactic acid bacteria (LAB) strains isolated from them remains underexplored. Sixty-six LAB strains were isolated from fermented foods using bacterial morphology, Gram staining, and catalase activity. The isolates were differentiated at strain level by RAPD-PCR (Random Amplification of Polymorphic DNA-Polymerase Chain Reaction) and twenty-five strains were selected for further evaluation of acid and bile salt tolerance. Among these, ten strains exhibited high tolerance and were subsequently assessed for adhesion to Caco-2 colorectal carcinoma cells, antimicrobial activity, exopolysaccharide (EPS) production, lysozyme resistance, and hemolytic activity. Using k-means clustering, three strains: Lactiplantibacillus plantarum ES-3, Pediococcus pentosaceus N-1, and Enterococcus faecium N-2 demonstrated superior probiotic characteristics, including significant acid (100% survival at pH3.0) and 0.3% bile salt tolerance (57%, 64%, 67%), strong adhesion to intestinal cells (65%, 88%, 91%), high lysozyme resistance (88%, 88%, 77%), and produced high amounts of EPS. These strains show promising potential as probiotics and warrant further investigation to confirm their functional properties and potential applications.Article Citation - WoS: 10Citation - Scopus: 11Effect of Bio-Mimicked Surface Texturing on the Shear Strength of Additively Manufactured Metal Single-Lap Joints: An Innovative Approach(Pergamon-Elsevier Science Ltd, 2025-06) Atahan, M. Gokhan; Maskery, Ian; Ashcroft, Ian; Apalak, M. Kemal; Pappas, AthanasiosIn this paper, we investigate the mechanical performance of metal single-lap joints featuring bio-mimicking surface textures. The inspiration for the surface textures was the foot and toe of the gecko, a creature whose ability to climb smooth shear surfaces is attributed to the mesoand micro-structures of its feet. Three surface textures were investigated: a hexagonal texture based on the central region of the foot, a lamellae-like texture based on the toe, and a mixed texture of both. Metal adherends with these textures were produced using the laser powder bed fusion (LPBF) additive manufacturing method. Finite element analysis was performed to examine the influence of surface texture on stress distribution in the adhesive layer, while mechanical testing was used to determine joint strength and failure mode. Compared to the as- printed surface texture, bio-mimicking surface textures improved the wettability of the bonding surfaces, and significantly improved the lap shear strength of the joints. Mechanical interlocking due to surface texture was more effective than the increase in bonding surface area in enhancing joint strength. The bio-mimicking textures improved the damage tolerance capacity of the joints by reducing local stress concentrations at the overlap edges of the adhesive layer and ensured that the adhesive failure type was mixed mode due to the mechanical interlocking effect. The presented novel bio-mimicked surface texture method offers promising results for both industrial applications and scientific studies.