Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
Browse
4 results
Search Results
Article Dimensionality Effects in Anisotropic Single Layers TiSe5 and TiTe5: a Comparative Study of 2D Sheets and 1D Nanochains(IOP Publishing Ltd, 2026) Can Dogan, Kadir; Kutay Tamdogan, Omer; Bozkurt, Yagmur; Cetin, Zebih; Yagmurcukardes, MehmetIn this study, we present a comprehensive first-principles investigation of the structural, vibrational, and electronic properties of titanium pentachalcogenide structures in both two-dimensional (2D) and one-dimensional (1D) nanochain (NC) forms. Total energy and geometry optimizations reveal that the 2D TiX5 (X = Se, Te) structures exhibit in-plane anisotropy arising from the trigonal prismatic TiX3 units interconnected via the chalcogenide chains. Phonon band dispersions and elastic tensor elements confirm the dynamical and mechanical stability of the 2D layers, respectively. Electronically, while TiTe5 is a metal, TiSe5 possesses direct band gap semiconducting behavior. In addition, free-standing 1D NC counterparts, which are sub-units of the 2D structures, are investigated by means of their stability. Three stable 1D NCs, namely TiTe5-NC, TiSe7-NC, and TiTe7-NC, are found to be composed of edge-sharing TiX6-like units with either five- or seven-fold coordination. The dynamically stable 1D NCs are shown to be semiconductors with relatively larger band gaps as compared to 2D layers. Predicted Raman spectra reveal clear signatures of vibrational mode evaluations as a result of quantum confinement from the 2D layer to the 1D NC. Moreover, finite-temperature ab-initio quantum molecular dynamics simulations at 300 K confirm the thermal stability of both the 2D TiX5 layers and 1D NC derivatives, showing that the Ti-based systems retain their structural integrity under ambient conditions and are feasible candidates for experimental synthesis. Our findings highlight the formation of stable semiconducting 1D NCs of Ti-pentachalcogenides from their 2D counterparts.Article Developing Gold Nanoparticles Decorated With Carbon-Dots for Multiplexed Cellular Imaging(IOP Publishing Ltd, 2025) Kavuranpala, Tugce; Saydullaeva, Iroda; Ozcelik, SerdarThis study focuses on developing a novel hybrid nanomaterial composed of gold nanoparticle decorated with carbon dots, termed AuNP@C-dot, as a versatile platform for multiplexed imaging. Structural and spectral characterizations confirmed the successful conjugation of C-dots to AuNPs via covalent bonding, as evidenced by FTIR, X-ray photoelectron spectra, HRTEM analyses, and UV-Vis and fluorescence spectroscopies. The fluorescence intensities of C-dots are doubled through the conjugation to the AuNPs. The conjugation of fluorescent C-dots to plasmon-resonant AuNPs enables simultaneous multicellular imaging by taking advantage of the fluorescent signaling of C-dots and the scattering signaling of AuNPs. In vitro studies using human lung cell lines (A549 and BEAS-2B) confirmed the multiplexed imaging and revealed efficient cellular uptake and subcellular localization of AuNP@C-dots, including nuclear translocation, which is critical for radiotherapy and photodynamic therapy. Cell viability assessments utilizing a colorimetric assay for measuring cell metabolic activity and a colony formation assay demonstrated good biocompatibility of AuNP@C-dots at relevant concentrations. It can be envisioned that the AuNP@C-dot hybrid system may improve the detection and monitoring of cell health and disease due to its dual-modal imaging capability. Furthermore, they could be used for supervising controlled release of therapeutic agents, tailored for enhanced treatment efficacy. This study demonstrates the potential of C-dot-conjugated AuNPs as a multifunctional tool with inherent control mechanisms for the next-generation cellular analysis, drug administration, and diagnostic strategies.Article Vision-Language Model Approach for Few-Shot Learning of Attention Deficit Hyperactivity Disorder Using EEG Connectivity-Based Featured Images(IOP Publishing Ltd, 2025) Catal, Mehmet Sergen; Gumus, Abdurrahman; Karabiber Cura, Ozlem; Aydin, Ocan; Zubeyir Unlu, MehmetTraditional medical diagnosis approaches have predominantly relied on single-modality analysis, limiting clinicians to interpreting isolated data streams such as images or time series. The integration of vision language models (VLMs) into neurophysiological analysis represents a paradigm shift toward multimodal diagnostic frameworks, enabling clinicians to interact with diagnosis models through diverse modalities including text, audio, visual inputs, etc. This multimodal interaction capability extends beyond conventional label-based classification, offering clinicians flexibility in diagnostic reasoning and decision-making processes. Building on this foundation, this study explores the application of VLMs to electroencephalography (EEG)-based attention deficit hyperactivity disorder (ADHD) classification, addressing a gap in neurophysiological diagnostics. The proposed framework applies VLM-based few-shot ADHD classification by converting raw EEG data into EEG connectivity-based featured images compatible with contrastive language-image pre-training's (CLIP) image encoder. The adaptor-based CLIP approach (Tip-Adapter and Tip-Adapter-F) for few-shot learning improves CLIP's zero-shot classification performance, achieving 78.73% accuracy with 1-shot and 98.30% accuracy with 128-shot using the RN50x16 backbone. Experiments investigate prompt engineering effects, backbone architectures of CLIP, patient-based classification, and combinations of EEG connectivity features. Comparative analysis is performed with two datasets to evaluate the approach between different data sources. Through the adaptation of pre-trained VLMs to neurophysiological data, this technique demonstrates the potential for multimodal diagnostic frameworks that enable flexible clinician-model interactions beyond conventional label-based classification systems. The approach achieves effective ADHD classification with minimal training data while establishing foundations for applying VLMs in clinical neuroscience, where diverse modality interactions through text, visual, and audio inputs can enhance diagnostic workflows. The code is publicly available on GitHub to facilitate further research in the field: https://github.com/miralab-ai/vlm-few-shot-eeg.Article Host Isotope Effects on the Oxygen Local Vibrations in Cdte(IOP Publishing Ltd, 2023) Tarhan, Enver; Ramdas, Anant K.Strong absorption peak observed near 350 cm-1 in the infrared spectrum of CdTe is assigned to a localized vibrational mode of 16O impurity atoms at tellurium sites. In this work, we studied the nature of these vibrations in terms of the effect of isotopic mass variations in the nearest neighbor Cd atoms. We showed that Cd atoms with 8 stable natural isotopes of varying abundances cause the observed line shape in the observed localized vibrational absorption peak. To calculate the effect of isotopic mass variations, we used the XY4 molecular model, X being the impurity atom at a host Te atom site and Y's are various isotopes of the host Cd atoms. Corresponding frequencies of local modes were calculated for each possible combinations of neighboring Cd atoms. For an XY4 molecule with Td symmetry, only the triply degenerate Gamma 5 mode is infrared active. The energies of this mode are higher than those of the others. This mode is possible only when all neigboring Cd atoms are the same isotope. To simulate the absorption data, we used a dynamical matrix approach where a force constant is given for each of the bending and stretching potential energy terms. By diagonalization of the dynamical matrix we were able to fit the calculated spectrum to the data with a proper choice of the bending and stretching force constants. A good agreement with the experiment as well as reported force constants for other impurities in CdTe is obtained.