WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7150
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Article Citation - WoS: 2Citation - Scopus: 2Fabrication of Bioactive Helix Aspersa Extract-Loaded Chitosan-Based Bilayer Wound Dressings for Skin Tissue Regeneration(Amer Chemical Soc, 2024) Perpelek, Merve; Tıhmınlıoğlu, Funda; Tamburaci, Sedef; Karakasli, Ahmet; Tihminlioglu, FundaIn recent years, there has been a notable shift toward exploring plant and animal extracts for the fabrication of tissue engineering structures that seamlessly integrate with the human body, providing both biological compatibility and physical reinforcement. In this particular investigation, we synthesized bilayer wound dressings by incorporating snail (Helix aspersa) secretions, comprising mucus and slime, into chitosan matrices via lyophilization and electrospinning methodologies. A nanofiber layer was integrated on top of the porous structure to mimic the epidermal layer for keratinocyte activity as well as acting as an antibacterial barrier against possible infection, whereas a porous structure was designed to mimic the dermal microenvironment for fibroblast activity. Comprehensive assessments encompassing physical characterization, antimicrobial efficacy, in vitro bioactivity, and wound healing potential were conducted on these bilayer dressings. Our findings revealed that the mucus and slime extract loading significantly altered the morphology in terms of nanofiber diameter and average pore size. Snail extracts loaded on a nanofiber layer of bilayer dressings showed slight antimicrobial activity against Staphylococcus epidermidis and Escherichia coli. An in vitro release study of slime extract loaded in the nanofiber layer indicated that both groups 1 and 2 showed a burst release up to 6 h, and a sustained release was observed up to 96 h for group 1, whereas slime extract release from group 2 continued up to 72 h. In vitro bioactivity assays unveiled the favorable impact of mucus and slime extracts on NIH/3T3 fibroblast and HS2 keratinocyte cell attachment, proliferation, and glycosaminoglycan synthesis. Furthermore, our investigations utilizing the in vitro scratch assay showcased the proliferative and migratory effects of mucus and slime extracts on skin cells. Collectively, our results underscore the promising prospects of bioactive snail secretion-loaded chitosan constructs for facilitating skin regeneration and advancing wound healing therapies.Article Machinability Investigation on Cnc Milling of Recycled Short Carbon Fiber Reinforced Magnesium Matrix Composites(Iop Publishing Ltd, 2024) Atasoy, Sahin; Kandemir, SinanThis study investigates the machinability of magnesium matrix composites reinforced with short carbon fibers, which represent novel materials in the field. AZ91 alloy and its composites containing 2.5 and 5 wt% recycled carbon fiber (rCF) reinforcements were used as workpieces. Face milling was conducted using uncoated carbide cutting tools under dry cutting conditions with varied cutting speeds (480-560-640 m min(-1)) and feed rates (0.65-0.8-0.95 mm min(-1)). The experimental design was based on the Taguchi L-9 (3(3)) orthogonal array. Analysis included cutting forces, surface roughness, wear on cutting inserts, and chip morphology to assess machinability. Taguchi, analysis of variance, and regression methods were employed to analyze cutting force and surface roughness results. Findings indicated satisfactory machinability for AZ91 alloy and comparatively poorer performance for the 5 wt% rCF reinforced composite, with increased reinforcement content correlating with higher cutting force and surface roughness. SEM and EDX analyses revealed significant built-up layer formation on cutting inserts, with predominantly spiral-shaped continuous chips observed in the experiments. Overall, the study affirmed the machinability of the composites and identified suitable cutting parameters for further investigations.Article Citation - WoS: 2Citation - Scopus: 2Exploring the Use of Water-Extracted Flaxseed Hydrocolloids in Three-Dimensional Cell Culture(Mary Ann Liebert, inc, 2024) Yildirim-Semerci, Ozum; Bilginer-Kartal, Rumeysa; Arslan-Yildiz, AhuPlant-derived hydrocolloids offer promising prospects in biomedical applications. Among these, Flaxseed hydrocolloid (FSH) can form a soft, elastic, and biocompatible hydrocolloid with tunable viscosity and superior swelling capacity, making it an attractive scaffold. This study introduces a green extraction method for FSH, employing a single-step aqueous extraction process and fabrication of FSH scaffold. Despite growing interest, the pristine form of FSH has not been investigated for sustainable long-term three-dimensional (3D) cell culture. Here, FSH scaffolds were thoroughly characterized for their morphological, chemical, mechanical, and biological properties. 3D cell culture experiments were conducted using NIH-3T3 mouse fibroblast cells, and cell viability was assessed using live/dead and Alamar Blue assays. High cell viability was sustained for long term compared with 2D cell culture. Cell adhesion and 3D cellular morphology on FSH scaffold for 30 days were monitored by scanning electron microscopy analysis. Also, collagen type-I and F-actin expressions were analyzed by immunostaining after 30 days of culture, resulting in 5- and 4-fold increments of fluorescence intensity, respectively. Results indicate sustained cell viability in the long term and favorable cell-material interaction, demonstrating the potential of FSH as a scaffold. This study emphasizes the importance of the green extraction approach, improving the biocompatibility and functionality of FSH tissue engineering applications. Impact Statement Flaxseed hydrocolloid (FSH) is a promising scaffold for biomedical applications due to its biocompatibility and tunable properties. This study introduces a green extraction method for FSH and evaluates its use in 3D cell culture with NIH-3T3 mouse fibroblast cells. The findings indicate high cell viability and enhanced cell-material interactions over 30 days, highlighting the potential of FSH for tissue engineering.Article Citation - WoS: 1Citation - Scopus: 1Chemical Composition Optimization and Isothermal Transformation of Δ-Transformation Plasticity Steel for the Third-Generation Advanced High-Strength Steel Grade(Wiley-v C H verlag Gmbh, 2024) Okur, Onur; Davut, Kemal; Palumbo, Gianfranco; Nalcaci, Burak; Guglielmi, Pasquale; Yalcin, Mustafa Alp; Erdogan, MehmetA new low-manganese transformation-induced plasticity steel is designed with optimized nickel content to achieve superior strength and ductility while minimizing the use of expensive nickel. The steel is optimized using JMatPro software, then cast, and hot rolled. To assess the effect of intercritical annealing on austenite (martensite at room temperature) volume fraction and carbon content, hot-rolled steel samples quenched from different annealing temperatures (680-1100 degrees C) are used. Additionally, hot-rolled steel coupons are intercritically annealed at about 50% austenite formation temperature (740 degrees C) and then subjected to isothermal treatments at 300-425 degrees C for varying times (10-90 min). After optimizing these treatments to maximize retained austenite (RA), tensile specimens are heat-treated first at 740 degrees C and then isothermally at 325 degrees C. Thermodynamic calculations suggest that aluminum combined with silicon may lead to the delta ferrite formation, and even minimal nickel content can stabilize a considerable amount of austenite. In the experimental studies, it is shown that lower-temperature bainitic holding enhances austenite stability by enriching the carbon content. Optimized two-stage heat treatments yield up to 25.8% RA, with a tensile strength of 867.2 MPa and elongation of 40.6%, achieving a strength-elongation product of 35.2 GPax%, surpassing the third-generation advanced high-strength steel grades minimum requirement of 30 GPax%.Article Citation - WoS: 1Comparison of Cell-Penetrating and Fusogenic Tat-Ha2 Peptide Performance in Peptideplex, Multicomponent, and Conjugate Sirna Delivery Systems(Amer Chemical Soc, 2024) Uz, Metin; Bulmus, Volga; Altinkaya, Sacide AlsoyIn this study, the performance of the cell-penetrating and fusogenic peptide, TAT-HA2, which consists of a cell-permeable HIV trans-activator of transcription (TAT) protein transduction domain and a pH-responsive influenza A virus hemagglutinin protein (HA2) domain, was comparatively evaluated for the first time in peptideplex, multicomponent, and conjugate siRNA delivery systems. TAT-HA2 in all three systems protected siRNA from degradation, except in the conjugate system with a low Peptide/siRNA ratio. The synergistic effect of different peptide domains enhanced the transfection efficiency of multicomponent and conjugate systems compared to that of peptideplexes, which was attributed to the surface configuration of TAT-HA2 peptides depending on the nature of attachment. Particularly, the multicomponent system showed better cellular uptake and endosomal escape than the peptideplexes, resulting in enhanced siRNA delivery in the cytoplasm. In addition, the presence of cleavable disulfide bonds in multicomponent and conjugate systems promoted the effective siRNA delivery in the cytoplasm, resulting in improved gene silencing activity. The multicomponent system reduced the level of luciferase expression in SKOV3 cells to 45% (+/- 4). In contrast, the conjugate system and the commercially available siRNA transfection agent, Lipofectamine RNAiMax, caused luciferase suppression down to 55% (+/- 2) at a siRNA dose of 100 nM. For the same dose, the peptideplex system could only reduce the luciferase expression to 65% (+/- 5). None of the developed systems showed significant toxicity at any dose. Overall, the TAT-HA2 peptide is promising as a siRNA delivery vector; however, its performance depends on the nature of attachment and, as a result, its surface configuration on the developed delivery system.Article Effect of Random Structural Variations on the Optical Properties of Honeycomb Photonic Crystals(Taylor & Francis Ltd, 2024) Tuncturk, Yigit; Sozuer, H. SamiPeriodic dielectric structures called photonic crystals are being used in various sensors and devices. Since photonic crystals are designed to operate within certain frequency ranges, accuracy in structure becomes important. In this work, we investigate the effects of two types of randomness, surface roughness and positional randomness, on the optical properties of the honeycomb photonic crystal. We employed the plane wave expansion method to investigate the effects of random perturbations of the shape and the position of the structure on the density of states. We also employ the finite-difference time-domain method to calculate the transmission spectrum as a consistency check. We find that both surface roughness and positional imperfections cause significant changes in the DOS. As the degree of randomness is increased, transverse electric and transverse magnetic gaps are narrowed and complete gaps totally disappear at $ 45\% $ 45% of surface roughness.Article Evaluation of Partially Reduced Keratins Extracted From Wool Fibers as a Hydrogel Forming Biomaterial(inst Tecnologia Parana, 2024) Yalcin, Damla; Top, AybenIn this study, it was aimed to prepare low-cost hydrogel from reduced keratin. Keratin proteins were obtained from Merino wool via three extraction methods. In the first method, keratins were reduced using sodium sulfide. In the second method, keratins extracted with the first method were precipitated with HCl. Urea, EDTA, and sodium sulfide were used in the third method. Extraction yields of method 1, method 2, and method 3 were determined as 44 +/- 2, 27 +/- 1, and 42 +/- 2 %, respectively. For all extraction methods, the average value of the free thiol amounts was obtained as 0.06 +/- 0.02 mmol SH/g keratin. A considerable portion of the highly polydisperse keratins was separated between similar to 40 kDa and similar to 60 kDa in the SDS-PAGE gel, and this fraction corresponds to alpha-keratin proteins with low sulfur content. A strong band at similar to 1654 +/- 1 cm(-1) detected in the FTIR spectra of the keratins confirms mainly alpha-helical secondary structure. The self- standing hydrogel was obtained upon incubating 15 wt. % keratin solution at 37 degrees C. Storage modulus and loss modulus of the hydrogel were determined as 1.3 +/- 0.08 kPa and 0.1 +/- 0.015 kPa, respectively. The keratin hydrogel is not cytotoxic to L929 mouse fibroblast cells, suggesting that this affordable hydrogel can be applied as a drug delivery/encapsulation system and in wound healing.Article Regression Via Classification for Fingerprint Orientation Estimation(Ieee-inst Electrical Electronics Engineers inc, 2024) Erdogmus, NesliEstimating the direction in which the ridges and valleys of the fingerprint pattern are aligned often serves as a pivotal first step in fingerprint recognition systems. The ridge orientation map is a fundamental reference for subsequent processing stages, such as image enhancement, feature extraction, and matching. Therefore, its accuracy is essential to achieve high recognition rates. Ridge orientation estimation entails a regression problem since the task is to estimate an angle between 0 degrees and 180 degrees for each sub-region in the fingerprint image. However, the majority of the approaches in the literature pivot towards framing this regression task as a classification problem. This paper systematically analyzes the regression via classification methodology for fingerprint orientation estimation, exploring various discretization and encoding strategies. Specifically, we examine single and multiple discretization schemes designed to ensure that resulting bins maintain uniform length or uniform probability or are allocated randomly, paired with one-hot, ordinal, and cyclic encoding techniques. Our experiments are conducted on the FOE-TEST database from FVC-onGoing, the sole publicly available fingerprint orientation dataset. The findings highlight the efficacy of cyclic encoding over the one-hot encoding prevalent in prior research, while equal-length and equal-probability discretization strategies yield comparable results.Review Citation - WoS: 13Citation - Scopus: 18Review of Cell Level Battery (calendar and Cycling) Aging Models: Electric Vehicles(Mdpi, 2024) Yarimca, Gulsah; Cetkin, ErdalElectrochemical battery cells have been a focus of attention due to their numerous advantages in distinct applications recently, such as electric vehicles. A limiting factor for adaptation by the industry is related to the aging of batteries over time. Characteristics of battery aging vary depending on many factors such as battery type, electrochemical reactions, and operation conditions. Aging could be considered in two sections according to its type: calendar and cycling. We examine the stress factors affecting these two types of aging in detail under subheadings and review the battery aging literature with a comprehensive approach. This article presents a review of empirical and semi-empirical modeling techniques and aging studies, focusing on the trends observed between different studies and highlighting the limitations and challenges of the various models.Article On the Rings Whose Injective Right Modules Are Max-Projective(World Scientific Publ Co Pte Ltd, 2024) Alagoz, Yusuf; Buyukasik, Engin; Yurtsever, Haydar BaranRecently, right almost-QF (respectively, max-QF) rings that is the rings whose injective right modules are R-projective (respectively, max-projective) were studied by the first two authors. In this paper, our aim is to give some further characterizations of these rings over more general classes of rings, and address several questions about these rings. We obtain characterizations of max-QF rings over several classes of rings including local, semilocal right semihereditary, right non-singular right Noetherian and right non-singular right finite dimensional rings. We prove that for a ring R being right almost-QF and right max-QF are not left-right symmetric. We also show that right almost-QF and right max-QF rings are not closed under factor rings. This leads us to consider the rings all of whose factor rings are almost-QF and max-QF.