IYTE GCRIS Database (Izmir Institute of Technology)
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Influence of Soil Characteristics on the Phytochemistry of Evergreen Ivy (Hedera Helix L.) Leaves in Deciduous Forests
No full textThe evergreen ivy (Hedera helix L.), traditionally used to treat respiratory conditions, contains triterpene saponins, primarily hederacoside C, and various phenolic compounds. This study investigated the relationships between the chemical composition of ivy leaves and their natural growing conditions (moisture, temperature, pH, and electrical conductivity of soil). Ivy leaves were collected monthly over 1 year from oak and beech forests. Hederacoside C, rutin, chlorogenic acid (ChA), neoChA, 4,5-dicaffeoylquinic acid (DCQA), and 3,5-DCQA were analyzed by high-performance thin-layer chromatography (HPTLC) and high-performance liquid chromatography (HPLC). Soil parameter data, along with the quantitative HPLC results of ivy leaves, were first subjected to bivariate analysis, which revealed significant correlations, particularly between soil moisture, soil temperature, and the chemical composition of ivy leaves. In addition, ivy samples were classified and clustered based on seasons by principal component analysis (PCA) and hierarchical cluster analysis (HCA), regardless of their collection sites. Digitized HPTLC chromatograms were evaluated by PCA and partial least squares discriminant analysis (PLS-DA) analyses; PCA enabled the grouping of ivy leaves based on their collection sites, and PLS-DA categorized the samples by seasons. The evaluation of the relationships between the phytochemistry of ivy leaves and their natural growing conditions has been reported for the first time
Tracing the Origins: Byzantine Lime Mortars From Anaia and St. Jean Churches (Western Türkiye) and Provenances of Natural Stone Aggregates
No full textThe aim of this study is to determine the provenances of natural stone aggregates of the lime mortars from the St. Jean and Anaia Churches, which represent two of the most significant Byzantine buildings in Western T ; uuml;rkiye. With this aim, the characterization study was conducted to define the physical properties and raw material compositions of lime mortars; hydraulic properties of the binders; mineralogical and chemical compositions, microstructural properties of lime, binders and aggregates; geochemical characteristics and pozzolanic activities of aggregates. The analyses were determined using X-ray diffraction (XRD), scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS), and thermogravimetric analysis (TGA). Furthermore, field observations and analytical studies were paired with the characterization results to determine the possible provenances. Analytical studies demonstrated that natural stone aggregates exhibited highly pozzolanic properties, which imparted hydraulicity to lime mortars. The macrostructure of the natural stone aggregates exhibited angular characteristics and a diverse lithological composition derived from the older brecciated clastics of the Menderes Massif. The fine-grained volcanic matrix of the aggregates was predominantly dacitic or rhyolitic in character, possibly derived from a breccia matrix composed of volcaniclastic materials. The findings suggested that the provenance of the natural stone aggregates were the breccia accumulation regions around Ayasuluk (Sel ; ccedil;uk) for the St. Jean Church and S ; ouml;ke-Germencik for the Anaia Church. The deliberate selection of natural stone sources to produce hydraulic lime mortars shows a conscious relationship with the surrounding geology during the Byzantine period
Numerical Assessment of Vertical Axis Hydrokinetic Turbine Efficiencies With Different Grate Protections
No full textHydrokinetic turbines are crucial for sustainable power generation, but their performance is often impacted by floating debris and sediment transport, which can damage turbine blades. Sediment retention enhances the turbine's lifespan and reduces maintenance by preventing blade erosion, cavitation and clogging. Protective grates reduce abrasive particle entry, minimising blade wear. They also avoid buildup of sediment, lowering the risk of blockages and cavitation, which harm efficiency and accelerate degradation. This study presents the numerical performance of Darrieus-type vertical axis hydrokinetic turbines under the impact of straight and Coanda type grate protection structures. The effects of these two types of grate structures with different design angles on turbine power coefficient (CP) and torque coefficient (CT) were investigated using the ANSYS Fluent program. The dynamic mesh technique simulated the turbine rotation and the semi-implicit method for pressure-linked equations (SIMPLE) was applied with a shear stress transport (SST) k-ω turbulence model. The turbine's efficiency was compared and the results were evaluated for steady and unsteady flow conditions. The highest power coefficients were obtained as 0.230 and 0.264 for steady and unsteady flow, respectively, in the Coanda grate with a 30° central angle. The highest power coefficients were obtained as 0.215 and 0.247 for steady and unsteady flow, respectively, in the straight grate design with a 60° inclination angle. The sediment retention capacities of Coanda grates (30° central angle) and straight grates (60° inclination angle) with varying particle size distributions were further investigated using the discrete phase model (DPM) under steady flow conditions. © 2025 The Author(s). IET Renewable Power Generation published by John Wiley ; Sons Ltd on behalf of The Institution of Engineering and Technology
Optimization of Resource-Aware Parallel and Distributed Computing: a Review
No full textThis paper presents a review of state-of-the-art solutions concerning the optimization of computing in the field of parallel and distributed systems. Firstly, we contribute by identifying resources and quality metrics in this context including servers, network interconnects, storage systems, computational devices as well as execution time/performance, energy, security, and error vulnerability, respectively. We subsequently identify commonly used problem formulations and algorithms for integer linear programming, greedy algorithms, dynamic programming, genetic algorithms, particle swarm optimization, ant colony optimization, game theory, and reinforcement learning. Afterward, we characterize frequently considered optimization problems by stating these terms in domains such as data centers, cloud, fog, blockchain, high performance, and volunteer computing. Based on the extensive analysis, we identify how particular resources and corresponding quality metrics are considered in these domains and which problem formulations are used for which system types, either parallel or distributed environments. This allows us to formulate open research problems and challenges in this field and analyze research interest in problem formulations/domains in recent years
Toward Accurate in Silico Prediction of Antigen Binding Affinities for Antibody Engineering
No full textIn clinical applications and life sciences research, antibodies represent an important diagnostic and therapeutic potential thanks to their high target affinity, specificity, and broad developability. While the antigen affinity, one of the primary success assessors of an antibody, can be measured at reasonably high precision and reliability, the scalability of the measurements can be cumbersome and limited. This is troubling because the affinity must be monitored throughout all steps of the developability approaches such as affinity maturation and humanization of an antibody. In this context, in silico approaches present a lucrative opportunity at a fraction of the cost and time typically invested in a comparable wet lab undertaking. In addition to their high-throughput potential, in silico approaches can provide an invaluable side product, i.e., identifying the molecular driving forces behind affinity. Here, we investigated the performance of six different high-throughput servers in two settings common in antibody engineering applications: (i) de novo prediction of the experimental antibody-antigen binding constants, and (ii) the free energy change in binding due to single point mutations. We find that the accuracy of these tools can be significantly low in the two regimes relevant to antibody development: (i) prediction of high-affinity binding, and (ii) prediction of favorable mutations. These issues are intricately related to the training sets used in the underlying models of these tools where high-affinity complexes and favorable point mutations are typically underrepresented. We showed that biophysical characteristics of single point mutations, especially changes in bulkiness and hydrophobicity, increase the prediction error. We argue that while the prediction of mutational impact can be predicted within one kcal per mol using re-parameterized versions of the present in silico tools, the de novo prediction of the affinity likely requires revisiting the underlying physical models behind these tools. © 202
CFD-DEM Investigation of the Effects of Particle Size and Fluidization Regime on Heat Transfer in Fluidized Beds
No full textThis paper presents an in-depth study of heat transfer in fluidized beds, employing the CFD-DEM technique. The primary focus is to examine the impacts of inlet gas velocity, fluidization regime, and particle size on the thermal behavior of fluidized beds. The results revealed that thermal convection predominantly governs heat transfer in fluidized beds, accounting for the largest fraction of the overall heat transfer process. Particle-fluid-particle thermal conduction was found to contribute approximately 10-20% of the heat transfer, whereas particle-particle conduction exhibits a minor role. Upon increasing the inlet gas velocity, the convection rate intensifies, whereas the particle-fluid-particle conduction rate decreases. Furthermore, the study highlights the differences in temperature distribution between turbulent and bubbling fluidized beds. Turbulent bed demonstrated a more uniform and homogenous particle temperature compared to bubbling. At similar fluidization numbers in bubbling beds, increasing particle diameter enhances thermal convection while reducing particle-fluid-particle conduction. In contrast, the turbulent regime shows minimal differences in heat transfer mechanisms when particle size varies. Additionally, smaller particles are found to significantly improve temperature uniformity in fluidized beds. A comprehensive comparison of simulation results with experimental data validates the accuracy of the employed model, reinforcing its ability to predict heat transfer in fluidized beds reliably. This research provides valuable insights into the complex interplay of various mechanisms of heat transfer within fluidized beds, enabling engineers and researchers to optimize bed performance and enhance temperature control in various industrial applications
Analysis and Comparison of the Projectile Impact Response of an Electron Beam Melt-Ti64 Body Centered Cubic Lattice-Cored Sandwich Plate
No full textBackground: One potential application of additively fabricated lattice structures is in the blade containment rings of gas turbine engines. The blade containment rings are expected to be able to absorb the kinetic energy of a released blade (broken blade) in order to protect the engine parts from damaging. Metallic lattice-cored sandwich plates provide a gap (free space) between two face sheets, which helps to arrest the released blade and increases the energy absorption capability of containment rings. Objective: The objective was to investigate numerically the projectile impact response of Body-Centered-Cubic (BCC) Electron-Beam-Melt (EBM) lattice-cored/Ti64 face sheet sandwich plates as compared with that of an equal-mass monolithic EBM-Ti64 plate. Methods: The projectile impact simulations were implemented in LS-DYNA using the previously determined flow stress and damage models and a spherical steel impactor at the velocities ranging from 150 to 500 m s−1. The experimental projectile impact tests on the monolithic plate were performed at two different impact velocities and the results were used to confirm the validity of the used flow stress and damage models for the monolithic plate models. Results: Lower impact stresses were found numerically in the sandwich plate as compared with the monolithic plate at the same impact velocity. The bending and multi-cracking of the struts over a wide area in the sandwich plate increased the energy absorption and resulted in the arrest of the projectile at relatively high velocities. While monolithic plate exhibited a local bent area, resulting in the development of high tensile stresses and the projectile perforations at lower velocities. Conclusions: The numerical impact stresses in the sandwich plate were distributed over a wider area around the projectile, leading to the fracture and bending of many individual struts which significantly increased the resistance to the perforation. Hence, the investigated lattice cell topology and cell, strut, and face sheet sizes and the lattice-cored sandwich plate was shown potentially more successful in stopping the projectiles than the equal-mass monolithic plates. © The Author(s) 2025
Monomer-Engineered Quinone-Based Conjugated Polymers for High-Rate Aqueous Zinc-Ion Batteries
No full textConjugated polymers (CPs) with their extended pi-conjugated structures have recently attracted tremendous attention as organic cathodes in aqueous zinc-ion batteries (AZIBs). In this study, two quinone-pyrrole conjugated polymers, QpCP-1 (benzoquinone monomer) and QpCP-2 (anthracenetetrone monomer), were synthesized to investigate the impact of monomer engineering on electrochemical performance, aiming to enhance specific capacity without sacrificing rate performance and cycle life. At 0.1 A g-1, QpCP-1 delivered a higher specific capacity (178 mA h g-1) than QpCP-2 (134 mA h g-1). However, while QpCP-1's capacity declined with increased current density, QpCP-2 demonstrated superior rate capability, retaining 78% of its initial capacity when the current density increased 20-fold (from 0.1 to 2.0 A g-1). This enhanced rate performance is attributed to QpCP-2's extended conjugated structure and increased accessible quinone-rich redox-active sites. Furthermore, QpCP-2 underwent gradual activation, resulting in a 30% increase in specific capacity, and demonstrated remarkable cycling stability over 10,000 cycles at 2.0 A g-1. The charge storage mechanism involving the coinsertion of H+ and Zn2+ was investigated through a series of ex situ characterization techniques. This work provides insights into the potential of CPs in AZIBs by elucidating the impact of monomer engineering and structural influences on electrochemical performance
Removal of Antimony(v) From Aqueous Solutions by Electrodeionization
No full textThis study investigates the removal efficiency of the toxic element antimony (Sb(V)) using a combined system incorporating ion exchange resins and ion exchange membranes to form an Electrodeionization (EDI) cell. The impact of various operational parameters, including applied potential, flow rate, Na₂SO₄ concentration in the electrode compartment, and the presence of interfering ions, on Sb(V) removal was systematically examined. Results indicate that increasing the applied potential significantly enhances Sb(V) removal, achieving a maximum removal rate of 99% at 40 V and 50 V, with the residual Sb(V) concentrations reducing to 60 μg/L and 9 μg/L, respectively. Variation in flow rate from 1 L/h to 3 L/h showed that removal efficiency peaks at 99% for flow rates of 2 L/h and above. Adjusting the Na₂SO₄ concentration from 0.005 M to 0.05 M in the electrode compartment also improves removal efficiency, maintaining a rate of 99%. Furthermore, the presence of low concentrations of Cl⁻, SO₄2⁻, NO₃⁻, and PO₄³⁻ ions resulted in achieving a 99% removal efficiency of Sb(V). These findings demonstrate the system's robustness and potential for effective Sb(V) removal from aqueous solutions under varying operational conditions. © 2025 Elsevier Lt
Esterase-Mediated Degradation of Dibutyl and Diethylhexyl Phthalates in Aqueous and Soil Systems
No full textPhthalate esters (PAEs), widely used as plasticizers, pose severe environmental and health risks. This study investigated the enzymatic hydrolysis of PAE congeners (dibutyl phthalate (DBP) and diethylhexyl phthalate (DEHP)) in aqueous and soil systems using Bacillus subtilis esterase and a new thermoalkaliphilic Geobacillus sp. esterase. A novel esterase secreted from Geobacillus sp. which was isolated from a geothermal region (Türkiye) was expressed in E.coli and purified. Geobacillus sp. esterase was able to degrade almost 30% of DBP and 40% of DEHP (100 mg/L) in the aqueous system within 336 h, while it degraded virtually 59% and 98% of DBP in agricultural area soil (soil-1) and forest area soil (soil-2), respectively, at the same time. To compare with Geobacillus sp. esterase, Bacillus subtilis esterase was used, which fully degraded DBP with 100 mg/L in the soil-1 and soil-2 for 72 h and 2 h, respectively. The performances of both esterases to degrade DEHP (100 mg/L) were similar in soil-1 (∼35%) and soil-2 (∼50%) for 336 h. Soil characteristics significantly influenced PAE degradation. Compared to that in the aqueous system, Geobacillus sp. esterase in soil systems had a higher degradation efficiency. This was likely due to its origin from a soil microorganism. Variations in the degradation ability of two enzymes most probably arose from substrate specificities and enzyme dynamics. Molecular docking results showed that DBP had a higher affinity to both enzymes than DEHP. Overall, this study offers important evidence that Bacillus subtilis esterase and Geobacillus sp. esterase are effective biocatalysts for removing the pollutants with ester bonds in the environment. © 2025 Elsevier Lt