IYTE GCRIS Database (Izmir Institute of Technology)
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Plasma-Enhanced Cvd Synthesis and Cytotoxic Evaluation of Graphitic Carbon Embedded – Fe3O4 Nanoparticles
No full textThis study reports the synthesis of graphitic carbon embedded - Fe3O4 nanoparticles using a novel method that enables a low-temperature rapid process and includes cytotoxicity tests to evaluate their potential use in biomedical applications. In this study, graphitic carbon was grown on Fe3O4 core using a plasma-enhanced chemical vapor deposition (PE-CVD) system under an Ar-H2-CH4 gas plasma at 650 °C for 15 min. X-ray diffractometry (XRD) and Raman spectroscopy investigations confirmed that Fe3O4 nanoparticles were embedded in graphitic carbon (Fe3O4@C). Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), along with transmission electron microscopy (TEM) equipped with EDS, also supported the carbon formation and nano-sized structure of the synthesized particles. Fe3O4@C nanoparticles exhibited soft magnetic properties with saturation magnetization (Ms) and coercivity (Hc) values of 69.27 emu/g and 97 Oe, respectively. Cytotoxicity assessment on HeLa and MCF7 cancer cells suggested biocompatibility at and below a dose of 100 μg/mL after 24 h of exposure but a drop in cell viability at higher doses and longer incubation times, more on cancer cell lines than the healthy L929 cells. These results suggest that Fe3O4@C nanoparticles might be potential candidates for biomedical applications, including drug delivery, photothermal therapy, and magnetically-triggered operations. © 2025 Elsevier Ltd and Techna Group S.r.l
Developments in Antimicrobial Food Packaging From Zein Incorporating Natural Active Agents
No full textIn this chapter, the current developments in using zein for antimicrobial food packaging have been discussed with particular emphasis on incorporated natural active agents. Although zein could be incorporated with antimicrobial enzymes and peptides, incorporation of phenolic compounds, essential oils, and organic acids into zein packaging have gained a particular interest as these natural antimicrobial agents also help reducing classical brittle nature of zein films. The composites or blends of zein with lipids and fatty acids still maintain their importance as antimicrobial films having sustained release properties. However, recent developments have also addressed different benefits of using zein nanofibers, nanoparticles, and nanoemulsions in packaging. Moreover, zein has also become a promising material to obtain antimicrobial electrospun mats. This chapter discusses not only traditional antimicrobial zein films and coatings, but also recently developed zein-based antimicrobial materials. © 2025 Elsevier Inc. All rights reserved
Hybrid Preceramic Aerogels for Oil and Solvent Cleanup
No full textThis study presents the first synthesis and characterization of monolithic hybrid preceramic aerogels using distinct drying techniques: ambient pressure (ambigels) and CO2 supercritical drying. Polymeric ambi/aerogels, derived from polyhydromethlysiloxane (PHMS) and divinylbenzene (DVB), are processed at 200 degrees C, while hybrid ceramic-polymer (ceramer) is produced through pyrolysis at 600 degrees C. Despite variations in drying methods, polymer and ceramer ambi/aerogels exhibit comparable microstructural characteristics, bulk density, pore size and volume, and specific surface area (542-841 m(2) g(-1)). Polymeric and ceramer ambigel with 90 vol% total porosity yield a compressive strength, reaching 2.5 MPa, demonstrating a low thermal conductivity of 0.046 W m-1 K-1. Sorption tests are conducted using oil and organic solvents in aqueous media to benefit their high hydrophobicity (112 degrees theta 142 degrees). Aerogels exhibit high sorption capacities: 13.17 g g(-1) for sesame oil, 11.74 g g(-1) for toluene, and 9.19 g g(-1) for n-hexane. The sorption rate for the oil is nearly 10 times slower than that for toluene and n-hexane. Regarding regeneration and reusability, polymer and ceramer aerogels show consistent sorption properties cycles tested for n-hexane and toluene
Synthesis of Nannochloropsis Oculata Cultivation Process Based on Mixed-Integer Formulations
No full textSophisticated mathematical formulations and related optimization tasks are important to favor microalgae processing. This study focuses on the development of a mixed integer nonlinear programming approach to calculate design and operational decisions through simultaneous and rigorous approach under set of complex constraints and objective functions. Through a set of differential algebraic equations, whose model parameters are obtained through fitting a dataset available in the literature, three case studies are demonstrated for the calculation of optimum cultivation conditions based on economic considerations and biomass production. The case studies show the impact of the approach for the sustainability of the process as different conditions are primary defined by light color, reactor size, dilution rate, feed stream composition, and growing medium are required for desired tasks. The approach is flexible and further modifiable to various considerations for more complex decision-making problems
Ggnn: Group-Guided Nearest Neighbors for Efficient Image Matching
No full textThe widely adopted image matching approach remains dependent on exhaustive matching of local features across images. Existing methods aiming to improve efficiency either approximate nearest neighbor (NN) search, compromising accuracy, or apply filtering only after establishing tentative matches, which restricts potential efficiency gains. We challenge the assumption that exhaustive NN search is necessary by proposing a more efficient hierarchical approach that maintains matching accuracy without relying on full-scale NN search. Our key insight is that efficiently identifying sufficiently similar, geometrically meaningful feature matches-rather than the most similar but geometrically random ones-can improve or maintain performance at a lower computational cost. We propose a novel method, Group-Guided Nearest Neighbors (GGNN), which matches groups of features first and then matches individual features only within these matched groups. This hierarchical pipeline reduces the computational complexity of feature matching from \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}\end{document} to \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}\end{document}, significantly improving efficiency. Experimental results on homography estimation demonstrate that GGNN outperforms standard NN search while achieving performance comparable to state-of-the-art methods. Additionally, we formulate GGNN as a general framework, where conventional NN search is a special case with a single global feature group. This formulation provides a continuum of feature matching methods with varying computational costs, enabling automatic selection based on a given time budget
Novel Single Layers of Holey Crystalline Strcutures of Hf8s12 With Diverse Magnetic States
No full textMotivated by recent experiments revealing the synthesizability of novel M 8 X 12 (where M=transition metal and X=S, Se, or Te) type holey structure transition metal chalcogenide crystals such as W8Se12, the structural, electronic and vibrational properties of the single layer Hf8S12 are investigated. Density functional theory (DFT) based total energy optimizations and dynamic stability analysis show that hafnium disulfide crystals with the known 1T phase are stabilized in the holey crystal structure represented by the chemical formula Hf8S12. While 1T-HfS2 crystals are nonmagnetic, holey Hf8S12 material exhibits 4 different magnetic states along with the ferromagnetic ground state. All these magnetic states display indirect or quasi-indirect narrow bandgap semiconducting behavior. Moreover, it is shown that the in-plane stiffness and Poisson ratio values of each possible magnetic phase of Hf8S12 has a distinctive angle dependency against applied strain. Its stable crystal structure and the magnetic diversity show that Hf8S12 can bean important candidate for magneto-mechanical applications
An Efficient Chebyshev Wavelet Collocation Technique for the Time-Fractional Camassa-Holm Equation
No full textBy employing the third-order Chebyshev collocation technique along with relevant wavelets, we tackle a third-order singular fractional partial differential equation (PDE). We directly build the Chebyshev operation matrix of the third kind, avoiding the use of the block-pulse function or any approximations. To reduce the order of equation in this approach, we transform the higher-order PDEs into a system of PDEs. Next, we utilize the third-kind Chebyshev wavelet collocation method to convert the resulting system from the prior step into a set of algebraic equations. To demonstrate the method's effectiveness, we apply it to the time-fractional Camassa-Holm equation and a third-order time-singular PDE. The outcomes are compared with those from several established methods to illustrate the method's efficiency and practicality
Developing Feasible Structural Flood Mitigation Measures for Arid Regions Using Hydrological and Hydraulic Modelling: a Case of Baledweyne City, Somalia
No full textFlood mitigation measures are essential in several aspects of environmental sustainability, such as environmental protection and development, infrastructure resilience, and climate change adaptation strategies. This study investigates several remedial measures such as flood and disaster risk reduction strategies to protect Baledwayne City, Somalia. The developed hydrological-hydraulic model is successfully calibrated using the 2019 flood event. Inundation maps for different mitigation measures are developed to determine the most appropriate one(s) that may reduce flood impact and protect the city, especially the residential areas, against peak discharge of a 500-year return period. The investigated mitigation measures include (1) operating the Warabole Diversion Canal, (2) building two detention ponds at the upstream sections of both right and left floodplains, (3) building levees (dikes) along both sides of Shabelle River, and (4) restoration of the river. Results show that the remedial measures for the Warabole Diversion Channel and the river restoration are insufficient to protect the city. Building ponds on the right- and left-hand sides of the river substantially protects the city from flooding by reducing the flooded area from 88.6 to 31.5 km2, which is equivalent to a reduction of 35.5%. Construction of dikes on both sides of the river does not protect the city by overflowing an area of 75.2 km2 (84.9%). A combination of several measures is also investigated and it is found that ponds must be built along with any alternative measure. When all four measures are combined, it becomes clear that the city's residential areas would be fully protected, significantly reducing the overall flooded area of the city to 27.9 km2 (31.5%). These flooded areas are behind the detention pond, which is designed to hold floodwater and gradually drain it back to the river
A Literature Review on Sustainable Buildings and Neighborhoods in Terms of Daylight, Solar Energy and Human Factors
No full textSustainability has become the focus and interest of researchers with climate change's increasing impact and challenges. Considering various perspectives, published studies focus on sustainability in architecture and the built environment, such as using daylight more effectively, enhancing energy efficiency, and designing nearly zero-energy buildings. Given the attention to sustain- ability in this domain, this review assesses the abovementioned viewpoints in buildings regarding environmental factors in relation to the micro and macro scales of the buildings and neighborhoods. Human factor has increasingly been of interest in recent works of sustainable environments. This study identifies the gaps with respect to architectural design elements considering daylighting, energy efficiency and human factors on building and neighborhood scales. A comprehensive table of the reviewed studies summarizes the aim, methodology, optimization algorithm, objective function, machine learning algorithm, digital tools, location, independent and dependent variables, view, wellness, well-being, daylight/energy performance metrics, scale, and solar strategy. The results showed that the current state-of-the-art focus on energy efficiency mainly considers passive design strategies at the building scale. Studies in the daylight domain primarily consider window properties, shading devices, and orientation. Human-centric studies showed that daylighting improves the emotional well-being of building occupants but can have negative effects such as overheating and glare. Overall findings emphasize the necessity of a holistic approach in achieving sustainability goals in dwellings at the building and neighborhood scale