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: 1Citation - Scopus: 1Synthesis of Pristine Chitosan Foams with Enhanced Pore Structure, Surface Area, and Mechanical Strength for Tissue Engineering Applications(Iop Publishing Ltd, 2025) Polat, Mehmet; Polat, Hürriyet; Ozdamar, A. B.; Polat, H.; 01. Izmir Institute of Technology; 04. Faculty of Science; 04.01. Department of Chemistry; 03. Faculty of Engineering; 03.02. Department of Chemical EngineeringWith its excellent biocompatibility, biodegradability, and antimicrobial activity, chitosan is a promising scaffold material for hard-tissue engineering. Yet, pristine chitosan foams typically lack the strength and porosity required for such use. Here we present a simple emulsion-templating approach to fabricate pristine chitosan foams with optimized strength and porosity. Sodium dodecyl sulfate (SDS), a widely used biocompatible anionic surfactant, was employed at trace levels to aid polymerization. The foams display a dual-scale pore morphology. Cavities of 150-300 mu m are separated by around 50 mu m thick chitosan walls containing large interconnecting openings. The walls are further populated with meso- and macropores of 50-500 nm. This architecture should support cell attachment and growth, facilitate proliferation, and enhance nutrient transport and metabolic exchange. The structure yields high surface area (up to 10 m2 g-1). Mechanically, the thick-walled cavities impart both elastic recovery and high compressive resistance (255 kPa at 40% strain from foams polymerized with 4% chitosan). A preliminary drug-release study using vancomycin confirmed excellent loading and sustained release.Article Citation - WoS: 1Citation - Scopus: 1Spiral-Shaped Dual-Port Microstrip Antenna for 5G/6G Applications With Wideband-To Transition Using Shape-Memory Alloy(Iop Publishing Ltd, 2025) Atac, Enes; Karatay, Anil; 01. Izmir Institute of TechnologyWe propose a compact, thermally reconfigurable dual-port microstrip antenna featuring a spiral-shaped design and shape-memory alloy (SMA) that enable switching between wideband and narrowband operation for 5G/6G communication systems. The SMA's thermally induced shape-memory behavior allows reconfiguration in response to temperature changes without the need for electronic or optical control circuits, thus avoiding issues such as self-interference problem, high costs, regular maintenance requirements, and durability concerns. In the wideband mode, measured results show that Port 1 covers 4.7-10.5 GHz and Port 2 covers 4.5-8.3 GHz, which closely agrees with simulations. When the SMA is activated by heat, the antenna switches to the narrowband mode, where Port 1 operates at 7.6 and 9.5 GHz, and Port 2 operates at 8.9 GHz. A ground-plane isolation element ensures low coupling between the ports, with the envelope correlation coefficient remaining below 0.1 across all configurations. The antenna reaches a peak gain of 5.2 dBi and maintains consistent performance through repeated switching. By combining spiral-shaped geometry with a responsive smart material, this work presents a novel and efficient approach for designing reconfigurable dual-port antennas suitable for future wireless technologies.Article The Curvature Perturbation Generated by Thermal Fluctuations During Thermal Inflation(Iop Publishing Ltd, 2025) Zoe, Heeseung; Mohammad, Hammam Raihan; Stewart, Ewan D.; Zoe, Heeseung; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of TechnologyDuring thermal inflation, the temperature determines the number of e-folds of expansion of the universe and so thermal fluctuations are magnified into curvature perturbations. We use classical thermodynamics to calculate the subhorizon thermal fluctuations and trace their evolution into superhorizon temperature perturbations. We convert the temperature perturbations into curvature perturbations using the delta N-formalism, or equivalently the junction condition of curvature perturbations at the end of thermal inflation, denoted by subscript c, and show that the late-time power spectrum is PR= 15 Hc 3 k3 4 pi 4 g & lowast;T 3 kc 3 . cArticle Citation - WoS: 2Citation - Scopus: 4Injectable Nanocomposite Hydrogels With Co-Delivery of Oxygen and Anticancer Drugs for Higher Cell Viability of Healthy Cells Than Cancer Cells Under Normoxic and Hypoxic Conditions(Iop Publishing Ltd, 2025) Kehr, Nermin Seda; Kehr, Nermin Seda; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of TechnologyInjectable nanocomposite hydrogels (NC hydrogels) have the potential to be used for minimally invasive local drug delivery. In particular, pH-sensitive injectable NC hydrogels can be used in cancer treatment to deliver high doses of anticancer drugs to the target site in cancer tissue without damaging healthy tissue. Recent studies have shown that in addition to stimuli-responsive delivery of anticancer drugs to cancer cells, oxygen delivery to the hypoxic environment of cancer tissue can lead to advanced effects, as hypoxia and an acidic pH are common characteristics of cancer tissue. However, few studies have investigated the effects of simultaneous administration of oxygen (O2) and pH-dependent anticancer drugs via injectable NC hydrogels on the viability of healthy and cancer cells under normoxic and hypoxic conditions. In this context, we describe the synthesis of injectable NC hydrogels composed of pH-responsive nanomaterials carrying oxygen and anticancer drugs. Our system provides sustained O2 release and pH-responsive sustained release of anticancer drugs for 15 and 30 d, respectively. Moreover, O2 delivery and/or simultaneous delivery of O2 and anticancer drug resulted in higher cell survival of healthy fibroblast cells than malignant Colo-818 cells under hypoxic conditions (1% O2) after 7 d of incubation.Review Citation - WoS: 1Citation - Scopus: 1Colloidal Quantum Dots as Solution-Based Nanomaterials for Infrared Technologies(Iop Publishing Ltd, 2024) Özçelik, Serdar; Taşcıoğlu, D.; Özçelik, S.; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of TechnologyThis review focuses on recent progress of wet-chemistry-based synthesis methods for infrared (IR) colloidal quantum dots (CQD), semiconductor nanocrystals with a narrow energy bandgap that absorbs and/or emits IR photos covering from 0.7 to 25 micrometers. The sections of the review are colloidal synthesis, precursor reactivity, cation exchange, doping and de-doping, surface passivation and ligand exchange, intraband transitions, quenching and purification, and future directions. The colloidal synthesis section is organized based on precursors employed: toxic substances as mercury- and lead-based metals and non-toxic substances as indium- and silver-based metal precursors. CQDs are prepared by wet-chemical methods that offer advantages such as precise spectral tunability by adjusting particle size or particle composition, easy fabrication and integration of solution-based CQDs (as inks) with complementary metal-oxide-semiconductors, reduced cost of material manufacturing, and good performances of IR CQD-made optoelectronic devices for non-military applications. These advantages may allow facile and materials' cost-reduced device fabrications that make CQD based IR technologies accessible compared to optoelectronic devices utilizing epitaxially grown semiconductors. However, precursor libraries should be advanced to improve colloidal IR quantum dot synthesis, enabling CQD based IR technologies available to consumer electronics. As the attention of academia and industry to CQDs continue to proliferate, the progress of precursor chemistry for IR CQDs could be rapid. © 2024 IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved.