Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 4Citation - Scopus: 2Elastic and Anelastic Behavior Associated With Structural Transitions in CsPbBr3(Amer Chemical Soc, 2025) Luo, Pingjing; He, Zhengwang; Yang, Dexin; Aktas, Oktay; Ding, Xiangdong; Zhang, XuefengStrain coupling and relaxation dynamics critically influence the photovoltaic and photoluminescent performances of metal halide perovskites. Here, resonant ultrasound spectroscopy is employed to study the elastic and anelastic properties associated with the octahedral tilting transitions in the optoelectronic semiconductor CsPbBr3 over the temperature range 303-468 K. The cubic-to-tetragonal transition near 405 K is marked by pronounced elastic softening accompanied by a sharp increase in acoustic loss. High anelastic loss below this transition reveals the presence of mobile ferroelastic twin walls that become pinned by lead vacancies at a temperature interval near 380 K in the tetragonal phase. The elastic softening in the cubic phase is strongly correlated to dynamic effects such as the local polar fluctuations. This local disordered effect is further verified by the anomalously high attenuation in the orthorhombic structure, in which the ferroelastic twin walls might become mobile.Article Citation - WoS: 1Citation - Scopus: 1Monomer-Engineered Quinone-Based Conjugated Polymers for High-Rate Aqueous Zinc-Ion Batteries(Amer Chemical Soc, 2025) Canakci, Utku Cem; Gecalp, Yasmin; Canturk, Batu Sercan; Erdogmus, Mustafa; Erozen, Yaren Naz; Buyukcakir, OnurConjugated 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.Article Citation - WoS: 4Citation - Scopus: 4Sulfonated Cellulose: a Strategy for Effective Methylene Blue Sequestration(Amer Chemical Soc, 2025) Toy, Mustafa; Recepoglu, Yasar Kemal; Arar, OzgurThis study investigates the sulfonation modification of cellulose for the removal of methylene blue (MB) from aqueous solutions. The prepared biosorbent was characterized, and its sorption capacity, kinetics, and thermodynamics were systematically evaluated. Fourier-transform infrared (FTIR) spectroscopy analyzed structural modifications, while scanning electron microscopy (SEM) examined the surface properties. The optimal sorbent dosage was determined as 0.05 g. MB removal efficiency increased from 11% at pH 1 to 70% at pH 2, reaching 99% within the pH range of 3 to 7. Kinetic studies revealed rapid sorption, achieving 99% removal within 3 min. Among various isotherm models, the Langmuir model provided the best fit (R 2 = 0.9989), indicating monolayer sorption with a maximum capacity of 37.65 mg/g. Thermodynamic analysis showed negative Delta G degrees values, confirming a spontaneous sorption process, while an enthalpy change (Delta H degrees) of -33.5 kJ/mol indicated exothermic behavior. The entropy change (Delta S degrees) of -82.6 J mol-1<middle dot>K-1 suggested decreased disorder during sorption. Regeneration studies demonstrated that 0.2 M HCl combined with ethanol achieved the highest desorption efficiency, and after three cycles, the MB removal efficiency remained above 99%. The presence of -SO3 - groups played a crucial role in MB sorption via ion exchange and may also contribute through hydrogen bonding, thereby enhancing MB sorption. These findings highlight sulfonated cellulose as an efficient and regenerable biosorbent for MB removal, offering valuable insights into its sorption mechanisms.Article Selective Growth of Fapbbr3 Nanocrystals With Precisely Tailored Optical Properties for Advanced Optoelectronic Applications(Amer Chemical Soc, 2025) Guvenc, C. Meric; Polat, Nahit; Arica, Tugce A.; Balci, SinanUnderstanding the evolution of semiconductor nanocrystals (NCs) during their colloidal synthesis is essential for achieving improved control over their physical and chemical properties. The fast reaction kinetics and concurrent nucleation and growth periods of lead halide perovskite NCs pose significant challenges in controlling the synthesis. Here, we present the room-temperature colloidal synthesis of FAPbBr3 NCs with physically decoupled nucleation and growth periods by using the common oleylamine and oleic acid ligand pair for lead halide perovskite NCs. Importantly, in this method, the nucleation and growth phases are entirely decoupled by halting the reaction at a metastable state, where the FAPbBr3 nuclei are formed. Subsequently, preformed FAPbBr3 nuclei are selectively grown by increasing supersaturation. This is achieved by reducing the monomer solubility through the injection of oleic acid into the solution. Notably, two-dimensional perovskite nanostructures form as intermediate products during the synthesis. Furthermore, the size of the FAPbBr3 NCs is tuned from 5.7 to 13.5 nm by controlling the injected oleic acid amount. Photoluminescence quantum yields of the FAPbBr3 perovskite NCs synthesized by using this method reached up to 95%. These findings demonstrate a robust strategy for the controlled synthesis of FAPbBr3 perovskite NCs, providing precisely tailored optical properties for advanced applications such as solar cells, photodetectors, and light-emitting diodes.Article Citation - WoS: 14Citation - Scopus: 15Predictive Modeling of Photocatalytic Hydrogen Production: Integrating Experimental Insights With Machine Learning on Fe/G-c3n4 Catalysts(Amer Chemical Soc, 2025) Arabaci, Bahriyenur; Bakir, Rezan; Orak, Ceren; Yuksel, AsliHydrogen emerges as a promising alternative to fossil fuels with its pollutant-free emissions, high energy density, versatility, and efficiency in generating power. In this study, photocatalytic hydrogen production from using 1000 ppm of model solution prepared with sucrose was investigated in the presence of Fe/g-C3N4 photocatalysts over Box-Behnken experimental design developed using the Minitab statistical software. The amount of hydrogen produced was optimized at different pH environments (3, 5, and 7) for 2 h reaction time with different amounts of metal loaded (10, 20, and 30 wt %), Fe/g-C3N4 (0.1, 0.2, and 0.3 g/L), and oxidant (H2O2; 0, 10, and 20 mM) concentrations. SEM, BET, XRD, FTIR, and PL analyses were employed for the characterization of synthesized photocatalysts. According to the response optimization, using Fe/g-C3N4, the optimal conditions for hydrogen production were found as 0.3 g/L catalyst loading, 18.8 mM H2O2, and 26.6% Fe loading by mass when the pH was 3 for the reaction medium. Furthermore, machine learning algorithms were employed to predict hydrogen evolution based on experimental parameters. Notably, ensemble models such as Voting Regressor combining the Bagging Regressor, Random Forest Regressor, LGBM Regressor, Extra Trees Regressor, XGB Regressor, and Gradient Boosting Regressor achieved superior performance with a mean squared error of 0.0068 and R-squared (R 2) of 0.9895. This integrated approach demonstrates the efficacy of machine learning in optimizing photocatalytic hydrogen generation processes.Article Citation - WoS: 7Citation - Scopus: 7Periodate-Mediated Cross-Linking for the Preparation of Catechol Conjugated Albumin Nanoparticles Used for in Vitro Drug Delivery(Amer Chemical Soc, 2025) Argitekin, Eda; Erez, Ozlem; Cakan-Akdogan, Gulcin; Akdogan, YasarConjugation of serum albumin protein with catechol-containing dopamine molecules provides an alternative method for the preparation of albumin nanoparticles (NPs). A commonly used desolvation method utilizes glutaraldehyde as a cross-linking agent. Here, the catechol cross-linking mechanism is used instead of glutaraldehyde providing advantages to prevent toxicity and an undesirable reaction of glutaraldehyde with cargo molecules. Covalent cross-linking between dopamine conjugated bovine serum albumin (D-BSA) proteins was obtained in the presence of sodium periodate (NaIO4) as an oxidizer. As a result, spherical D-BSA NPs with a uniform size distribution of around 100 nm in diameter and negative zeta potential around -28 mV were prepared. Optimal conditions were reached when a dopamine:IO4 - molar ratio of 2:1, pH 7.4 of the medium, and acetone as the desolvating agent were used. Furthermore, the obtained NPs display antioxidant properties, have rapid biodegradability in the presence of trypsin, and have a high doxorubicin (DOX) loading (9.1%) with a sustainable drug release. DOX loaded D-BSA NPs also caused up to 90% breast cancer cell (MCF-7) death within 24 h. These results show that drug carrying albumin NPs can alternatively be prepared via covalently cross-linked catechol groups and used in drug delivery studies.Article Citation - WoS: 2Citation - Scopus: 2Temperature-Dependent Spectral Properties of Hexagonal Boron Nitride Color Centers(Amer Chemical Soc, 2025) Ari, Ozan; Polat, Nahit; Firat, Volkan; Cakir, Ozgur; Ates, SerkanColor centers in hexagonal boron nitride (hBN) are emerging as a mature platform for single-photon sources in quantum technology applications. In this study, we investigate the temperature-dependent spectral properties of a single defect in hBN to understand the dominant dephasing mechanisms due to phonons. We observe a sharp zero-phonon line (ZPL) emission accompanied by Stokes and anti-Stokes optical phonon sidebands assisted by the Raman-active low-energy (approximate to 6.5 meV) interlayer shear mode of hBN. The shape of the spectral lines around the ZPL is measured down to 78 K, at which the line width of the ZPL is measured as 211 mu eV. Using a quadratic electron-phonon interaction, the temperature-dependent broadening and the lineshift of the ZPL are found to follow a temperature dependence of T + T 5 and T + T 3, respectively. Furthermore, the temperature-dependent line shape around the ZPL at low-temperature conditions is modeled with a linear electron-phonon coupling theory, which results in a 0 K Debye-Waller factor of the ZPL emission as 0.59. Our results provide insights into the underlying mechanisms of electron-phonon coupling in hBN, which is critical to enhance their potential for applications in quantum technologies.Article Radially Aligned Carbon Nanotube Glass Fiber Composites as Ion-Selective Microelectrodes(Amer Chemical Soc, 2025) Onder, Ahmet; Ng, Zhi Kai; Tsang, Siu Hon; Alagappan, Palaniappan; Teo, Edwin Hang Tong; Yildiz, Umit HakanDetection of ions is challenging due to their small size, rapid diffusion, and high mobility, especially for assaying in samples of low volumes. Among the traditional analytical methods, potentiometric ion-selective electrodes (ISE) have become a popular choice for detecting ions as they are cost-effective, user-friendly and can be miniaturized, making them useful for on-site analysis. In this context, radially aligned carbon nanotubes (RACNT) directly grown on glass fibers (GF) via the chemical vapor deposition method is investigated as a solid contact material for the fabrication of ion-selective microelectrodes (mu ISE) upon incorporating specific ionophores within a polymeric encapsulation membrane. As an illustration, sensitive detection of ammonium ions is accomplished by the fabricated mu ISE (plasticized PVC membrane containing nonactin ionophores), which yielded a LOD and a linear response range between 7.5 x 10-6 and 1.0 x 10-5 to 1.0 x 10-1 M, respectively. The mu ISE fabricated with RACNT-GF as an interface material exhibited improvements in LOD and enhanced the detection selectivity as compared to a conventional ISE fabricated using planar solid contact materials such as graphite. We hypothesize that the fabricated mu ISE with a high surface area and mechanical durability maximize the accommodation of ionophores in the barrier membrane for yielding improved potentiometric responses. Experimental results illustrate that the mu ISE possesses the potential to be utilized for the fabrication of selective and sensitive ISE upon incorporation of specific ionophores with RACNT-GF composites.Article Citation - WoS: 5Citation - Scopus: 5Light-Induced, Liquid Crystal-Templated Fabrication of Large-Area Pure Nanoporous Gold Films With High-Density Plasmonic Cavities(Amer Chemical Soc, 2024) Orhan, Ozan Baran; Polat, Nahit; Demir, Seren; Balci, Fadime Mert; Balci, SinanNanoporous gold (NPG) films are three-dimensional gold (Au) frameworks characterized by a uniform distribution of nanoscale irregular pores. Typically produced via a dealloying process, where the less noble silver (Ag) is selectively etched out, NPG films offer a large surface area, excellent chemical stability, remarkable catalytic activity, unique optical properties, and biocompatibility. These attributes make them invaluable for applications in catalysis, plasmonics, biosensors, and nanophotonics. However, the presence of residual Ag from the dealloying process can limit their performance in certain applications. In this study, we report a novel method for the fabrication of ultrapure, large-area NPG films (several cm2) using a light-induced and liquid crystal-templated method. A hexagonal lyotropic liquid crystal containing a strong acid and a nonionic surfactant is combined with an aqueous solution of HAuCl4, followed by the photochemical synthesis of gold nanoparticles (NPs) within the liquid crystal. After calcination of the Au NP-containing liquid crystal film at high temperature, pure NPG films are produced. We demonstrate surface-enhanced Raman spectroscopy (SERS) of Rhodamine 6G (R6G) molecules adsorbed on the NPG films and detect extremely low concentrations (below 10-6 M) of R6G. Additionally, we thoroughly investigated the formation and optical properties of the NPG films. The results reveal that the ultrapure NPG films contain high-density plasmonic nanocavities, where substantial electromagnetic fields are generated, leading to significant enhancement of optical processes at nanoscale dimensions.Article Citation - WoS: 4Citation - Scopus: 4Organolabeler: a Quick and Accurate Annotation Tool for Organoid Images(Amer Chemical Soc, 2024) Kahveci, Burak; Polatli, Elifsu; Bastanlar, Yalin; Guven, SinanOrganoids are self-assembled 3D cellular structures that resemble organs structurally and functionally, providing in vitro platforms for molecular and therapeutic studies. Generation of organoids from human cells often requires long and costly procedures with arguably low efficiency. Prediction and selection of cellular aggregates that result in healthy and functional organoids can be achieved by using artificial intelligence-based tools. Transforming images of 3D cellular constructs into digitally processable data sets for training deep learning models requires labeling of morphological boundaries, which often is performed manually. Here, we report an application named OrganoLabeler, which can create large image-based data sets in a consistent, reliable, fast, and user-friendly manner. OrganoLabeler can create segmented versions of images with combinations of contrast adjusting, K-means clustering, CLAHE, binary, and Otsu thresholding methods. We created embryoid body and brain organoid data sets, of which segmented images were manually created by human researchers and compared with OrganoLabeler. Validation is performed by training U-Net models, which are deep learning models specialized in image segmentation. U-Net models, which are trained with images segmented by OrganoLabeler, achieved similar or better segmentation accuracies than the ones trained with manually labeled reference images. OrganoLabeler can replace manual labeling, providing faster and more accurate results for organoid research free of charge.
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