PubMed İndeksli Yayınlar Koleksiyonu / PubMed Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7645
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Article Temporal Coherence of Single Photons Emitted by Hexagonal Boron Nitride Defects at Room Temperature(Amer Chemical Soc, 2026) Martinez-Pons, Juan Vidal; Kim, Sang Kyu; Behrens, Max; Izquierdo-Molina, Alejandro; Menendez Rua, Adolfo; Pacal, Serkan; Anton-Solanas, CarlosColor centers in hexagonal boron nitride (hBN) emerge as promising quantum light sources at room temperature, with potential applications in quantum communications, among others. The temporal coherence of emitted photons (i.e., their capacity to interfere and distribute photonic entanglement) is essential for many of these applications. Hence, it is crucial to study and determine the temporal coherence of this emission under different experimental conditions. In this work, we report the coherence time of the single photons emitted by an hBN defect in a nanocrystal at room temperature, measured via Michelson interferometry. The visibility of this interference vanishes when the temporal delay between the interferometer arms is a few hundred femtoseconds, highlighting that the phonon dephasing processes are 4 orders of magnitude faster than the spontaneous decay time of the emitter. We also analyze the single photon characteristics of the emission via correlation measurements, defect blinking dynamics, and its Debye-Waller factor. Our room temperature results highlight the presence of a strong electron-phonon coupling, suggesting the need to work at cryogenic temperatures to enable quantum photonic applications based on photon interference.Article Protection of N-Type (Ni,Fe)TiSb Half-Heusler Materials Against Static and Cyclic Oxidation Using a Si-Doped Cr Coating(Amer Chemical Soc, 2025) Gurtaran, Mikdat; Zhang, Zhenxue; Li, Xiaoying; Dong, HanshanIn this study, Cr-Si coatings were deposited on N-type (Ni,Fe)TiSb thermoelectric (TE) materials by using a closed-field unbalanced magnetron sputtering PVD technique. Oxidation behavior was evaluated under both isothermal (static) conditions (500 degrees C for 10 h and 600 degrees C for 50 h) and thermal cycling regimens (500 and 600 degrees C for 10 or 50 1 h cycles). Mass gain, surface morphology, cross-sectional microstructure, elemental distribution, and phase composition were examined by using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). Regardless of exposure mode, uncoated samples oxidized severely: a duplex scale formed, consisting of an outer TiO2 layer and a subjacent NiSb-rich zone, accompanied by extensive cracking and delamination. In sharp contrast, the Cr-Si coatings remained thermally stable and highly oxidation-resistant, maintaining the substrate's integrity during both static and cyclic tests. After exposure, coated samples showed negligible mass gain, no discernible morphological change, and no mechanical damage, confirming that the Cr-Si layer markedly enhances thermal durability and prevents surface degradation.Article Citation - WoS: 1Citation - Scopus: 1Electrochemical Sensors for Rapid Cardiovascular Disease Diagnostics(Amer Chemical Soc, 2025) Sanko, Vildan; Tekin, H. CumhurCardiovascular diseases (CVDs) remain a leading cause of death, particularly in developing countries, where their incidence continues to rise. Traditional CVD diagnostic methods are often time-consuming and inconvenient, necessitating more efficient alternatives. Rapid and accurate measurement of cardiac biomarkers released into body fluids is critical for early detection, timely intervention, and improved patient outcomes. Electrochemical methods offer a robust solution by enabling rapid, sensitive, selective, and multiplex detection of CVD biomarkers, paving the way for early diagnosis and treatment advancements. This review highlights the performance and potential of electrochemical sensors for detecting specific CVD biomarkers and related organic molecules. It explores electrochemical sensing mechanisms, their evolution, the integration of nanotechnology, and diverse sensing platforms. It also examines emerging technologies such as microfluidic, smartphone-integrated sensors, and microneedle- and tattoo-based sensors. Challenges and opportunities in integrating electrochemical sensors into point-of-care (POC) and wearable devices are discussed. Finally, the review compares commercial CVD sensors with existing methods and outlines future directions to advance the field.Article Enabling Fluorescence Lifetime Imaging Multiplexing Using UnaG Through Its Modification With Canonical and Noncanonical Amino Acids(Amer Chemical Soc, 2025) Terekhova, Valentina V.; Bodunova, Daria V.; Gorokhov, Egor S.; Tsoraev, Georgy V.; Sidorenko, Svetlana V.; Vasilev, Ruslan A.; Kirpichnikov, Mikhail P.Fluorogen-activating proteins are powerful molecular tools for microscopy, including functional imaging. These proteins serve as an alternative to GFP-like proteins, as they do not require oxygen for chromophore maturation. However, the restricted selectivity of proteins to chromophores, combined with the limited number of spectral channels of conventional fluorescent microscopes, hinders the development of multicolor synthetic dyes. Additionally, the poor cell and tissue permeability of synthetic chromophores further limits their utility. In this work, we address these challenges by combining time-resolved methods with the rational design of the UnaG protein, which utilizes bilirubin as a natural chromophore. To turn UnaG into a palette of probes for fluorescence lifetime imaging microscopy (FLIM), we solved two practical problems: first, we determined the limits of bilirubin lifetime variations in response to changes in the protein structure and, second, we determined what minimal structural changes can be reliably distinguished by lifetime analysis in cellula. Combining classical point mutagenesis and the translational introduction of noncanonical amino acids, we generated UnaG with fluorescence lifetimes ranging from hundreds of picoseconds to nanoseconds. We explored the potential for further modification of the UnaG protein matrix to optimize spectral and temporal characteristics of bilirubin fluorescence and its quantitative detection through time-resolved approaches.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 Durable ZrB2–ZrC Composite Materials as Advanced Electrodes for High-Performance Supercapacitors(Amer Chemical Soc, 2025) Paksoy, Aybike; Gungor, Ahmet; Yildirim, Ipek Deniz; Arabi, Seyedehnegar; Erdem, Emre; Balci-Cagiran, OzgeBoride and carbide-based materials attract increasing attention as promising options for energy storage applications. This research focuses on synthesizing pure boride and carbide compounds of zirconium (ZrB2 and ZrC) and their composite powders using mechanical activation-assisted route and subsequent heating processes. The chemical and microstructural characterization results indicate that the synthesized composite powders are of high purity, possess submicron-scale particle sizes (below 400 nm), and exhibit a high surface area of up to 9.41 m2/g. Supercapacitor devices, using the resulting powders as symmetrical electrodes, exhibit high energy density values ranging from 5.8 to 8.8 Wh/kg. The ZrB2-15 wt % ZrC composite sample achieves the highest power density at 155 W/kg, compared to 118 W/kg for the pure ZrB2 sample. Cycling tests demonstrate exceptional capacitance retention (99.4-99.9%) and cyclic stability, even after 5000 cycles, highlighting the high durability of the composite samples. These findings show that ZrB2-ZrC composites exhibit high energy and power density values and excellent cycling performance, making them strong candidates for use in high-performance supercapacitor devices.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 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 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: 7Citation - Scopus: 6Thickness Gradient in Polymer Coating by Reactive Layer-By Assembly on Solid Substrate(Amer Chemical Soc, 2023) Özenler, Sezer; Alkan, Ali Ata; Gunay, Ufuk Saim; Dağlar, Özgün; Durmaz, Hakan; Yıldız, Ümit HakanThe study describes a simple yet robust methodology for forming gradients in polymer coatings with nanometer-thickness precision. The thickness gradients of 0-20 nm in the coating are obtained by a reactive layer-by-layer assembly of polyester and polyethylenimine on gold substrates. Three parameters are important in forming thickness gradients: (i) the incubation time, (ii) the incubation concentration of the polymer solutions, and (iii) the tilt angle of the gold substrate during the dipping process. After examining these parameters, the characterization of the anisotropic surface obtained under the best conditions is presented in the manuscript. The thickness profile and nanomechanical characterization of the polymer gradients are characterized by atomic force microscopy. The roughness analysis has demonstrated that the coating exhibited decreasing roughness with increasing thickness. On the other hand, Young's moduli of the thin and thick coatings are 0.50 and 1.4 MPa, respectively, which assured an increase in mechanical stability with increasing coating thickness. Angle-dependent infrared spectroscopy reveals that the C-O-C ester groups of the polyesters exhibit a perpendicular orientation to the surface, while the C=C groups are parallel to the surface. The surface properties of the polymer gradients are explored by fluorescence microscopy, proving that the dye's fluorescence intensity increases as the coating thickness increases. The significant benefit of the suggested methodology is that it promises thickness control of gradients in the coating as a consequence of the fast reaction kinetics between layers and the reaction time.