PubMed İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/397
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Article Disorder-Engineered Hybrid Plasmonic Cavities for Emission Control of Defects in HBN(American Chemical Society, 2026-02-07) Genc, Sinan; Yucel, Oguzhan; Aglarci, Furkan; Rodriguez-Fernandez, Carlos; Yilmaz, Alpay; Caglayan, Humeyra; Bek, AlpanDefect-based quantum emitters in hexagonal boron nitride (hBN) are promising building blocks for scalable quantum photonics due to their stable single-photon emission at room temperature. However, enhancing their emission intensity and controlling the decay dynamics remain significant challenges. This study demonstrates a low-cost, scalable fabrication approach to integrate plasmonic nanocavities with defect-based quantum emitters in hBN nanoflakes. Using the thermal dewetting process, we realize two distinct configurations: stochastic Ag nanoparticles (AgNPs) on hBN flakes and hybrid plasmonic nanocavities formed by AgNPs on top of hBN flakes supported on gold/silicon dioxide (Au/SiO2) substrates. While AgNPs on bare hBN yield up to a 2-fold photoluminescence (PL) enhancement with reduced emitter lifetimes, the hybrid nanocavity architecture provides a dramatic, up to 100-fold PL enhancement and improved uniformity across multiple emitters, all without requiring deterministic positioning. Finite-difference time-domain (FDTD) simulations and time-resolved PL measurements confirm size-dependent control over decay dynamics and cavity-emitter interactions. Our versatile solution overcomes key quantum photonic device development challenges, including material integration, emission intensity optimization, and spectral multiplexity.Article Measuring Disaster Resilience in MENA Countries and Its Impact on Disaster Losses(Nature Portfolio, 2025-12-08) Demir, Abdullah; Dincer, Ali Ersin; Dincer, Nazire NergizDisaster resilience is a protective feature aimed at reducing the effects of natural disaster events and losses resulting from these events. This study develops a Disaster Resilience Index (DRI) for MENA countries to assess resilience across ten dimensions, including economic, social, institutional, infrastructural, and environmental factors. Unlike most prior studies, which focus on individual countries or use narrower sets of indicators, this study provides a multi-country, region-specific framework tailored to MENA's socio-economic and environmental heterogeneity. The index integrates geospatial data on disaster risk from geographic information systems (GIS) and a natural hazard risk dimension. Validation using disaster-related fatalities, supported by a dual PCA-based sensitivity analysis, confirms the robustness of the DRI and reveals that countries with stronger governance, higher human capital, and robust infrastructure tend to exhibit greater resilience, while fragile states and resource-dependent economies are more vulnerable. Notably, the DRI calculated using both dimension-specific and all-indicator PCA produces closely aligned values, indicating the choice of conducting PCA at the dimension level does not significantly alter the overall assessment of disaster resilience. These insights provide a foundation for targeted disaster risk reduction strategies and highlight areas where international cooperation and policy interventions can strengthen resilience in the region.Article Vim-Polyp: Multimodal Colon Polyp Dataset with Video, Histopathology, and Protein Expression(Nature Portfolio, 2025-12-03) Dogan, Refika Sultan; Akay, Ebru; Dogan, Serkan; Yilmaz, BulentThe dataset in this study includes 202 videos with a total of 422 minutes, reaching Kayseri City Hospital's gastroenterology department as colonoscopy videos and 1903 microscopy images between 2019 and 2021. It includes 399 colonoscopy, microscopy images, and pathological diagnoses of polyps, as well as immunohistochemical staining results for proteins that play an important role in the assessment of cancerous cells, such as staining results for p53 (clone: bp53-11), Ki-67 (clone: 30-9), CD34 (clone: QBend/10), PD-L1 (clone: SP142), BRAF (clone: V600E) and VEGF (clone: SP125). By sharing the data openly, we aim to facilitate benchmarking, exploratory analysis and transfer-learning studies on colorectal polyps and cancer. In combination with external datasets or pretrained models, the resource can help advance data-driven detection and characterisation work. The diverse range of polyps assigned to cancer stages from 201 patients makes this tool valuable for researchers and clinicians in furthering diagnosis and treatment.Article Burg-Aided 2D MIMO Array Extrapolation for Improved Spatial Resolution(MDPI, 2025-10-12) Bekar, Muge; Bekar, Ali; Pirkani, Anum; Baker, Christopher John; Gashinova, MarinaIn this paper, the extrapolation of a 2D multiple-input multiple-output (MIMO) array is proposed using the Burg algorithm to achieve higher angular resolution beyond that of the corresponding 2D MIMO virtual array. The main advantage of such an approach is that it allows us to dramatically decrease both the physical size and the number of antenna elements of the MIMO array. The performance and limitations of the Burg algorithm are examined through both simulation and experimentation at 77 GHz. The experimental methodology used to acquire 3D data of range, azimuth and elevation information with the 1D MIMO off-the-shelf radar is described. Using this method, the performance of the proposed array can be tested experimentally, especially at frequencies where it is desired to assess the antenna response prior to fabricating the antenna.Article Citation - Scopus: 1Labyrinthine Microstructures With a High Dipole Moment Boron Complex for Molecular Physically Unclonable Functions(American Chemical Society, 2025-10-29) Yıldız, T.A.; Kiremitler, N.B.; Kayacı, N.; Kalay, M.; Özcan, E.; Deneme, I.; Usta, H.The design and development of novel molecular-physically unclonable functions (PUFs) with advanced encoding characteristics and ease of fabrication have recently attracted attention in cryptography, secure authentication, and anticounterfeiting. Here, we report the development of a new high dipole-moment small molecule, InIm-BF<inf>2</inf>, a difluoroborate complex of an indolyl-imine ligand, and the fabrication of unique labyrinthine patterns through a facile two-step thin film process under ambient conditions. The new molecule has a dipolar, coplanar π-backbone and arranges in the solid state with antisymmetric cofacial π-stackings (3.86 Å). These properties, along with short C–H···π contacts (2.74–2.88 Å) and nonclassical C–H···F hydrogen bonds (2.47–2.51 Å) (23.4% and 11.5% of the Hirshfeld surfaces, respectively), drive the formation of amorphous molecular PUF patterns with disordered, short-range interactions. Spin-coating followed by thermal annealing at a moderate temperature produces nanoscopic molecular thin films with intricate labyrinthine patterns. These patterns, characterized by interconnected, irregularly shaped, micron-sized (≈50–100 μm) features, exhibit excellent PUF characteristics, verified through advanced image analysis and computational algorithms. Unlike randomly positioned isolated features in classical binarized keys, the interconnected labyrinthine patterns possess rich entropy and complex features, directly authenticated via deep-learning methodologies. Our work not only demonstrates a facile, promising approach to fabricating unique high-entropy PUF patterns but also provides critical insights into designing advanced molecular materials for next-generation security applications. © 2025 The Authors. Published by American Chemical SocietyArticle Citation - WoS: 2Citation - Scopus: 2Antifungal Efficacy of 3D-Cultured Palatal Mesenchymal Stem Cells and Their Secreted Factors Against Candida albicans(American Chemical Society, 2025-09-19) Bicer, M.; Öztürk, E.; Sener, F.; Hakki, S.S.; Fidan, O.Candida albicans is among the life-threatening fungal species and the primary contributor to hospital-acquired systemic infections, accounting for nearly 70% of all fungal infections worldwide. The current treatment primarily relies on azoles, pyrimidine analogs, polyenes, and echinocandins. However, growing antifungal resistance highlights the urgent need for the development of alternative treatments against C. albicans. Mesenchymal stem cells (MSCs) offer huge therapeutic potential for the treatment of C. albicans-associated diseases. In this study, palatal adipose tissue-derived MSCs (PAT-MSCs) and PAT-MSCs cultured in 3D biomaterial using nanofibrillar cellulose were tested against C. albicans strains ATCC 10231 and ATCC MYA 2876 using an in vitro antifungal activity assay. In addition, the conditioned medium from both PAT-MSCs and PAT-MSCs cultured in 3D hydrogel biomaterial (CM-PAT-MSCs-3D) were evaluated for their antifungal activities. The combined effect of PAT-MSCs and their secreted factors was also investigated. The expression of five antimicrobial peptide (AMP)-encoding genes was analyzed by quantitative real-time PCR. The expression of antimicrobial peptides was further confirmed via immunocytochemical staining. PAT-MSCs significantly inhibited the growth of C. albicans strains at varying inoculum concentrations (500 and 2000 CFU). Similarly, a comparable antifungal effect was observed when Candida strains were treated with PAT-MSC secreted factors alone. Statistical analysis revealed significant differences between the antifungal activities of PAT-MSCs and CM-PAT-MSCs. Lastly, the combination of PAT-MSCs and CM-PAT-MSC-3D led to a marked reduction in fungal growth, with inhibition rates of 99.75% and 99.91% for C. albicans ATCC 10231 and ATCC MYA-2876, respectively, at 500 CFU inocula. At 2000 CFU inocula, inhibition rates were 99.54% and 99.91%, respectively (****P ≤ 0.0001). These antifungal activities were further confirmed by using RT-PCR and immunocytochemical analysis. Our findings underscore a perspective on the potent antifungal activity of secreted factors from PAT-MSCs cultured within a 3D hydrogel matrix, specifically against various strains of C. albicans. Particularly, the combination of PAT-MSCs with their secreted factors represents a promising therapeutic platform, potentially offering a safer and more effective alternative to conventional antifungal treatments. © 2025 Elsevier B.V., All rights reserved.Article Citation - WoS: 8Citation - Scopus: 8Writing Chemical Patterns Using Electrospun Fibers as Nanoscale Inkpots for Directed Assembly of Colloidal Nanocrystals(Royal Soc Chemistry, 2020) Kiremitler, N. Burak; Torun, Ilker; Altintas, Yemliha; Patarroyo, Javier; Demir, Hilmi Volkan; Puntes, Victor F.; Onses, M. SerdarApplications that range from electronics to biotechnology will greatly benefit from low-cost, scalable and multiplex fabrication of spatially defined arrays of colloidal inorganic nanocrystals. In this work, we present a novel additive patterning approach based on the use of electrospun nanofibers (NFs) as inkpots for end-functional polymers. The localized grafting of end-functional polymers from spatially defined nanofibers results in covalently bound chemical patterns. The main factors that determine the width of the nanopatterns are the diameter of the NF and the extent of spreading during the thermal annealing process. Lowering the surface energy of the substrates via silanization and a proper choice of the grafting conditions enable the fabrication of nanoscale patterns over centimeter length scales. The fabricated patterns of end-grafted polymers serve as the templates for spatially defined assembly of colloidal metal and metal oxide nanocrystals of varying sizes (15 to 100 nm), shapes (spherical, cube, rod), and compositions (Au, Ag, Pt, TiO2), as well as semiconductor quantum dots, including the assembly of semiconductor nanoplatelets.Article Citation - WoS: 24Citation - Scopus: 26Wireless Measurement of Elastic and Plastic Deformation by a Metamaterial-Based Sensor(MDPI, 2014-10-20) Ozbey, Burak; Demir, Hilmi Volkan; Kurc, Ozgur; Erturk, Vakur B.; Altintas, AyhanWe report remote strain and displacement measurement during elastic and plastic deformation using a metamaterial-based wireless and passive sensor. The sensor is made of a comb-like nested split ring resonator (NSRR) probe operating in the near-field of an antenna, which functions as both the transmitter and the receiver. The NSRR probe is fixed on a standard steel reinforcing bar (rebar), and its frequency response is monitored telemetrically by a network analyzer connected to the antenna across the whole stress-strain curve. This wireless measurement includes both the elastic and plastic region deformation together for the first time, where wired technologies, like strain gauges, typically fail to capture. The experiments are further repeated in the presence of a concrete block between the antenna and the probe, and it is shown that the sensing system is capable of functioning through the concrete. The comparison of the wireless sensor measurement with those undertaken using strain gauges and extensometers reveals that the sensor is able to measure both the average strain and the relative displacement on the rebar as a result of the applied force in a considerably accurate way. The performance of the sensor is tested for different types of misalignments that can possibly occur due to the acting force. These results indicate that the metamaterial-based sensor holds great promise for its accurate, robust and wireless measurement of the elastic and plastic deformation of a rebar, providing beneficial information for remote structural health monitoring and post-earthquake damage assessment.Article Citation - WoS: 39Citation - Scopus: 51What Are the Key Success Factors for Strategy Formulation and Implementation? Perspectives of Managers in the Hotel Industry(Elsevier Sci Ltd, 2020-08) Koseoglu, Mehmet Ali; Altin, Mehmet; Chan, Eric; Aladag, Omer FarukThis study investigates how hotel managers describe strategy and identify key success factors for its formulation and implementation. The study analyzes qualitative data collected through semi-structured interviews with property level top managers of hotels in Hong Kong. The findings show that hotel managers prioritize competition analysis and macro-environmental conditions over internal characteristics such as teamwork in strategy formulation. In the implementation phase, however, internal considerations such as employee involvement and strategic consensus are given prominence. This study provides a significant contribution by examining how top level practitioners in the industry interpret success factors in their strategic management efforts, and it highlights a largely neglected area in the hospitality and tourism management literature.Article Citation - WoS: 16Citation - Scopus: 22Ultrasonic-Assisted Production of Precipitated Calcium Carbonate Particles From Desulfurization Gypsum(Elsevier, 2021-04) Altiner, Mahmut; Top, Soner; Kaymakoglu, BurcinThis study aimed to investigate the effect of ultrasonic application on the production of precipitated calcium carbonate (PCC) particles from desulfurization gypsum via direct mineral carbonation method using conventional and venturi tube reactors in the presence of different alkali sources (NaOH, KOH and NH4OH). The venturi tube was designed to determine the effect of ultrasonication on PCC production. Ultrasonic application was performed three times (before, during, and after PCC production) to evaluate its exact effect on the properties of the PCC particles. Scanning electron microscope (SEM), X-ray diffraction (XRD), Atomic force microscope (AFM), specific surface area (SSA), Fourier transform infrared spectrometry (FTIR), and particle size analyses were performed. Results revealed the strong influence of the reactor types on the nucleation rate of PCC particles. The presence of Na+ or K+ ions in the production resulted in producing PCC particles containing only calcite crystals, while a mixture of vaterite and calcite crystals was observed if NH4+ ions were present. The use of ultrasonic power during PCC production resulted in producing cubic calcite rather than vaterite crystals in the presence of all ions. It was determined that ultrasonic power should be conducted in the venturi tube before PCC production to obtain PCC particles with superior properties (uniform particle size, nanosized crystals, and high SSA value). The resulting PCC particles in this study can be suitably used in paint, paper, and plastic industries according to the ASTM standards.