Araştırma Çıktıları / Research Outputs

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3D and 4D printing of MXene-based composites: from fundamentals to emerging applications
(Royal Soc Chemistry, 2024) Bigham, Ashkan; Zarepour, Atefeh; Khosravi, Arezoo; Iravani, Siavash; Zarrabi, Ali
The advent of three-dimensional (3D) and four-dimensional (4D) printing technologies has significantly improved the fabrication of advanced materials, with MXene-based composites emerging as a particularly promising class due to their exceptional electrical, mechanical, and chemical properties. This review explores the fundamentals of MXenes and their composites, examining their unique characteristics and the underlying principles of their synthesis and processing. We highlight the transformative potential of 3D and 4D printing techniques in tailoring MXene-based materials for a wide array of applications. In the field of tissue regeneration, MXene composites offer enhanced biocompatibility and mechanical strength, making them ideal for scaffolds and implants. For drug delivery, the high surface area and tunable surface chemistry of MXenes enable precise control over drug release profiles. In energy storage, MXene-based electrodes exhibit superior conductivity and capacity, paving the way for next-generation batteries and supercapacitors. Additionally, the sensitivity and selectivity of MXene composites make them excellent candidates for various (bio)sensing applications, from environmental monitoring to biomedical diagnostics. By integrating the dynamic capabilities of 4D printing, which introduces time-dependent shape transformations, MXene-based composites can further adapt to complex and evolving functional requirements. This review provides a comprehensive overview of the current state of research, identifies key challenges, and discusses future directions for the development and application of 3D and 4D printed MXene-based composites. Through this exploration, we aim to underscore the significant impact of these advanced materials and technologies on diverse scientific and industrial fields. This review highlights the developments in the 3D/4D printing of MXene-based composites, focusing on their application in tissue regeneration, drug delivery, sensing, and energy storage.
3D FEA of Hollow and Solid Design Zirconia Dental Dowels
(Wiley, 2016) Kayahan, Mehmet Baybora; Ozkurt-Kayahan, Zeynep; Yay, Kubilay; Kazazoglu, Ender
PurposeThe aim of this study was to evaluate the stress distribution of hollow and solid design zirconia dowels. Materials and MethodsFinite element analysis (FEA) was used to investigate the influence of different dowel designs on the stress distribution of zirconia dowels. The coronal diameter of the dowel was 2.2 mm, the apical diameter was 1.8 mm, and the length was 15 mm. The diameter of the hollow space was 1.2 mm. Occlusal forces (both parallel and oblique) of 100 N were applied from the wider edge of the dowels simulating loads acting on the incisor during clenching and incising. The results were expressed in terms of von Mises criteria. ResultsFEA revealed differences in stress distribution. During parallel load, the maximum tensile stress of the hollow design (89.40 MPa) was greater than the solid design (43.30 MPa). During oblique load, the maximum tensile stress of the hollow design (1437.90 MPa) was greater than the solid design (917.96 MPa). The maximum deformation was observed in the coronal part of the dowel in both designs under the two load directions. ConclusionsFEA results showed that the hollow design zirconia dowels presented higher tensile stress.
A 3D finite element analysis of stress distribution on different thicknesses of mineral trioxide aggregate applied on various sizes of pulp perforation
(Springer Heidelberg, 2020) Ozkurt-Kayahan, Zeynep; Turgut, B.; Akin, H.; Kayahan, M. B.; Kazazoglu, E.
Objectives The aim of this study was to evaluate the stress distribution on different thicknesses of mineral trioxide aggregate (MTA) placed on various widths of pulp perforations during the condensation of the composite resin material. Materials and methods The mandibular molar tooth was modeled by COSMOSWorks program (SolidWorks, Waltham, MA). Three finite elemental analysis models representing 3 different dimensions of pulp perforations, 1, 2, and 3 mm in diameter, were created. The perforation area was assumed as filled with MTA with different thicknesses, 1, 2, and 3 mm for each pulp perforation width, creating a total of 9 different models. Then, a composite resin material was layered on MTA for each model. A 66.7 N load was applied and an engineering simulation program (ANSYS, Canonsburg, US) was used for the analysis. Results were presented considering von Mises stress criteria. Results As MTA thickness increased, the stress values recorded within the area between pulp and MTA decreased. Strain was decreased when the thickness of MTA increased. Conclusions Stresses at MTA-pulp interface and strain on MTA decreased with the increase in MTA thickness.
5-Year clinical performance of ceramic onlay and overlay restorations luted with light-cured composite resin
(Elsevier Sci Ltd, 2024) Yurdaguven, Gulsah Yenier; Ciftcioglu, Elif; Kazokoglu, Fatma Sehnaz; Kayahan, Mehmet Baybora
Objectives: This prospective clinical trial evaluated the clinical performance of ceramic partial coverage indirect adhesive restorations (PCIARs) in posterior teeth luted with a light-cured composite resin. Methods: From April 2016 to January 2017, a total of 60 patients (27 males, 33 females; mean age: 42.2 +/- 10.86 years old) received 83 glass-ceramic PCIARs (26 onlay, 57 overlay) made of IPS Emax CAD (Ivoclar Vivadent). All restorations were luted with a light-cured composite resin (Filtek Z250, 3 M ESPE) by two operators. Two independent calibrated examiners blinded to the operators performing the treatment evaluated the restorations at baseline, 1-year, and 5-year following FDI World Dental Federation criteria including esthetic, functional, and biological properties. Data were analyzed with the Friedman test and the Wilcoxon sign test (p p < 0.05). Results: None of the restorations failed due to fracture or retention loss. One restoration was clinically unsatisfactory because of secondary caries. Marginal staining (p:0.000), marginal adaptation (p:0.018) showed significant differences between 1-year and 5-year recall. Conclusions: The PCIARs demonstrated excellent clinical performance at 1-year period. The degradation parameters appeared as minor staining and minor irregularities after 5-year, without any affect on the clinical performance.
ABSTRACT CAPACITY OF REGIONS AND COMPACT EMBEDDING WITH APPLICATIONS
(Springer, 2011) Shakhmurov, Veli
The weighted Sobolev-Lions type spaces W-p,gamma(l) (Omega; E) boolean AND L-p,L-gamma (Omega; E-0) are studied, where E-0, E are two Banach spaces and E-0 is continuously and densely embedded on E. A new concept of capacity of region Omega is an element of R-n in Wp,gamma(l)(Omega; E-0, E) is introduced. Several conditions in terms of capacity of region Omega and interpolations of E-0 and E are found such that ensure the continuity and compactness of embedding operators. In, particular, the most regular class of interpolation spaces E-alpha between E-0 and E, depending of alpha and l, are found such that mixed differential operators D-alpha are bounded and compact from W-p,gamma(l)(Omega; E-0, E) to E-alpha-valued L-p,L-gamma spaces. In applications, the maximal regularity for differential-operator equations with parameters are studied.
Abstract Differential Equations with VMO Coefficients in Half Space and Applications
(Springer Basel Ag, 2016) Shakhmurov, Veli
In this paper, L (p) -separability properties of boundary value problems for elliptic and parabolic differential-operator equations with VMO coefficients are studied in half plane. In application, the maximal regularity properties of the anisotropic elliptic equation and system of equations with VMO coefficients are derived.
Abstract elliptic operators appearing in atmospheric dispersion
(Springeropen, 2014) Shakhmurov, Veli B.; Sahmurova, Aida
In this paper, the boundary value problem for the differential-operator equation with principal variable coefficients is studied. Several conditions for the separability and regularity in abstract L-p-spaces are given. Moreover, sharp uniform estimates for the resolvent of the corresponding elliptic differential operator are shown. It is implies that this operator is positive and also is a generator of an analytic semigroup. Then the existence and uniqueness of maximal regular solution to nonlinear abstract parabolic problem is derived. In an application, maximal regularity properties of the abstract parabolic equation with variable coefficients and systems of parabolic equations are derived in mixed L-p-spaces.
Abstract elliptic operators appearing in atmospheric dispersion (vol 2014, pg 43, 2014)
(Springer international Publishing Ag, 2014) Shakhmurov, Veli B.; Sahmurova, Aida
[No Abstract Available]
Abstract parabolic problems with parameter and application
(Elsevier Science inc, 2013) Shakhmurov, Veli B.; Sahmurova, Aida
In this work, the uniform well-posedenes of singular perturbation problems for parameter dependent parabolic differential-opera tor equations is established. These problems occur in phytoremediation modelling. (C) 2013 Elsevier Inc. All rights reserved.
Academic Writing in a Global Context: The Politics and Practices of Publishing in English
(Tesol, 2012) Yigitoglu, Nur
[No Abstract Available]
Academic Writing: At the Interface of Corpus and Discourse
(Pergamon-elsevier Science Ltd, 2012) Yigitoglu, Nur
[No Abstract Available]
Accelerating the reaction process of sodium carbonate-activated slag mixtures with the incorporation of a small addition of sodium hydroxide/sodium silicate
(Elsevier Sci Ltd, 2023) Dai, Xiaodi; Ren, Qiang; Aydin, Serdar; Yardimci, Mert Yucel; De Schutter, Geert
This paper investigates the possibility of accelerating the slowly progressive early reaction process of sodium carbonate-activated slag mixtures by adding a small amount of sodium hydroxide or sodium silicate to the so-dium carbonate activator. The reaction process of sodium carbonate-activated slag mixtures was evaluated by isothermal calorimetry and ultrasonic wave technology. Test results showed that adding a small amount of so-dium hydroxide or sodium silicate to the sodium carbonate activator significantly accelerated the reaction process, resulting in shortened setting times and enhanced mechanical properties. Only 1% Na2O contribution from sodium hydroxide addition can lead to a 2-d compressive strength of 20 MPa for sodium carbonate -activated slag mixtures. In addition, the 28 days compressive strength was significantly higher than the sole sodium carbonate activator. The addition of sodium hydroxide or sodium silicate also considerably influenced the rheological behavior of the sodium carbonate-activated slag mixture, enhancing the structural build-up rate and transforming the shear-thinning behavior to Bingham or shear-thickening behavior. A more well-packed microstructure was observed in the mixtures with the addition of sodium hydroxide; however, more micro -cracks were observed in the mixtures with a small incorporation of sodium silicate.
Accreditation: Crucial in World Trade, Public Safety, and Human Rights
(Ieee-inst Electrical Electronics Engineers inc, 2014) Sevgi, Levent
Accreditation is discussed. World-wide accreditation institutes are reviewed. Conformity Europe (CE) marking, procedures, and standards for accreditation, certification, and calibration are summarized through electromagnetic compatibility (EMC) tests and measurements. Error, uncertainty, and statistical evaluations and proficiency tests with typical results are presented.
Accuracy of single implant scans with a combined healing abutment-scan body system and different intraoral scanners: An in vitro study
(Elsevier Sci Ltd, 2021) Cakmak, Gulce; Donmez, Mustafa Borga; Atalay, Sevda; Yilmaz, Hakan; Kokat, Ali Murat; Yilmaz, Burak
Objective: The aim of the present study was to evaluate the accuracy of single implant scans with a combined healing abutment-scan body (CHA-SB) system using different intraoral scanners. Methods: A partially edentulous model with an implant was fabricated, and a CHA-SB system was secured on the implant. The model was scanned using an industrial-grade blue light scanner (ATOS Core 80) and a master reference model was generated (MRM). The model was also scanned with 4 different intraoral scanners (IOSs) [(Virtuo Vivo (VV), TRIOS 3 (T3), Omnicam (CO), and Primescan (PS)]. Test scans (n = 8) were superimposed over the MRM using the best fit algorithm (GOM Inspect 2018; GOM GmbH). After superimpositions, distance and angular deviations at selected areas on CHA-SB system were calculated. The data were analyzed with a 1way ANOVA and Tukey HSD tests for trueness and precision (alpha=0.05). Results: The differences in trueness (distance deviations) among tested IOSs were nonsignificant (P=.652). VV presented the highest angular deviations (P <=.031), and the angular deviations in other IOS scans were not found different (P >=.378). The precision of distance deviation data was not significantly different among scanners (P=.052). For the precision of angular deviation data, significant differences were found among IOSs (P=.002). Compared with PS (P=.007) and T3 (P=.014), VV had significantly lower precision, which was not significantly different than that of CO (P=.815). Conclusions: The accuracy (angular deviation) of scans of a combined healing abutment-scan body system on a single implant varied depending on the IOS. VirtuoVivo scans had the lowest accuracy in terms of angular deviations. When the distance deviation data were considered, scan accuracy of scanners was similar. Clinical Significance: A recently introduced combined healing abutment-scan body system combines the acquisition of both the implant and the soft tissue. When different intraoral scanners scan the combined healing abutment-scan body system, the scan accuracy may vary.
Accuracy of six intraoral scanners for scanning complete-arch and 4-unit fixed partial dentures: An in vitro study
(Mosby-elsevier, 2022) Diker, Burcu; Tak, Onjen
Statement of problem. The digital scan accuracy of different intraoral scanners (IOSs) for long-span fixed prosthesis and the effect of the starting quadrant on accuracy is unclear. Purpose. The purpose of this in vitro study was to evaluate the accuracy of 6 IOSs for complete-arch and prepared teeth digitally isolated from the complete-arch and to determine the effect of the starting quadrant on accuracy. Material and methods. A maxillary model containing bilaterally prepared canines, first molar teeth, and edentulous spans between the prepared teeth was used. The model was scanned by using a highly accurate industrial scanner to create a digital reference data set. Six IOSs were evaluated: TRIOS, iTero, Planmeca Emerald, Cerec Omnicam, Primescan, and Virtuo Vivo. The model was scanned 10 times with each IOS by 1 operator according to the protocols described by the manufacturers. Five scans were made starting from the right quadrant (ScanR), followed by 5 scans starting from the left quadrant (ScanL). All data sets were obtained in standard tessellation language (STL) file format and were used to evaluate accuracy (trueness and precision) with a 3D analyzing software program (Geomagic Studio 12; 3D Systems) by using a best-fit alignment. The prepared teeth were digitally isolated from the complete-arch and evaluated with the analyzing software program. The Kruskal-Wallis and Mann-Whitney U statistical tests were used to detect differences for trueness and precision (alpha=.05). Results. Statistically significant differences were found regarding IOSs (P<.003) and scanning sequence (P<.05). The TRIOS showed the best trueness for the complete-arch, but not statistically different from Primescan, Virtuo Vivo, and iTero (P>.003). The lowest median values for precision of the complete-arch were also found using TRIOS, but no significant difference was found among the scanners (P>.003). In terms of trueness and precision, Primescan had the best accuracy for preparations. Emerald showed significant differences depending on the scanning sequence for complete-arch accuracy. ScanR for trueness (P=.021) and ScanL for precision (P=.004) showed improved results. However, Emerald, TRIOS, and Virtuo Vivo showed statistically significant differences in precision of preparations depending on scanning sequence. ScanL deviated less than ScanR when scanned with TRIOS (P=.025) and Emerald (P=.004), and the opposite with Virtuo Vivo (P=.008). In terms of preparations trueness, no significant difference was found between the ScanR and ScanL of any IOS (P>.05). Conclusions. Based on this in vitro study, the accuracy of the complete-arch and prepared teeth differed according to the IOS and scanning sequence.
Accurate Prediction of Physical Properties of Different Freons Via Different Machine Learning Models
(Pergamon-Elsevier Science Ltd, 2025) Du, Jiahao; Karimi, Maryam; Khalaf, Mohammed I.; Al-Nussairi, Ahmed Kateb Jumaah; Singh, Narinderjit Sawaran Singh; Hasson, Ahmed Rasol; Hashemi, M.
Accurate prediction of refrigerant properties is essential for the design, optimization, and energy efficiency of cooling systems. R-12 and R-22 are among the most widely used refrigerants in industrial and domestic applications. Yet, their thermodynamic behavior is highly nonlinear and difficult to represent with traditional models, particularly under varying operating conditions. These challenges underscore the need for advanced data-driven methods, and machine learning presents a promising solution for enhancing predictive performance. In this research, four machine learning techniques were applied. The models considered were Least-Squares Boosting (LSBoost), Generalized Linear Model (GenLin), Multi-Layer Perceptron Artificial Neural Network (MLP-ANN), and Support Vector Regression (SVR). A dataset collected under controlled laboratory conditions was used for training and testing. The goal was to predict three fundamental refrigerant properties, namely density, velocity, and temperature. These properties were selected because they significantly impact refrigerant mass flow rate, heat transfer efficiency, pressure drop, and overall system performance. The analysis showed that LSBoost consistently achieved the highest predictive accuracy. In density estimation, it achieved an RMSE of 7.69E-04, a Pearson correlation coefficient of 0.9935, a coefficient of determination of 0.9968, a mean absolute percentage error of 5.7847, and a Kling-Gupta efficiency of 0.9736. In contrast, the Generalized Linear Model delivered substantially weaker results. In velocity prediction, LSBoost achieved a Pearson correlation coefficient of 0.9982 and an RMSE of 2.30 x 10(-5), with a coefficient of determination of 0.9978. At the same time, the Multi-Layer Perceptron reached only 0.2132 for the coefficient of determination. For temperature estimation, LSBoost produced an RMSE of 4.3644, a Pearson correlation coefficient of 0.9983, and a coefficient of determination of 0.9992, in contrast to Support Vector Regression, which yielded an RMSE of 92.344. Overall, the study demonstrated that LSBoost was a highly accurate and reliable tool for predicting complex thermodynamic properties of refrigerants, supporting its application in thermodynamic modeling and refrigeration system design. However, the relatively small dataset and simplified input features represented important limitations that may reduce generalizability. Future research should therefore involve larger and more diverse datasets to strengthen the applicability of the proposed approach in real-world engineering contexts.
Accurate Prediction of the Rheological Behavior of Mwcnt-Al2O3/ Water-Ethylene Glycol Nanofluid With Metaheuristic-Optimized Machine Learning Models
(Elsevier France-Editions Scientifiques Medicales Elsevier, 2025) Ru, Yi; Ali, Ali B. M.; Qader, Karwan Hussein; Abdulaali, Hanaa Kadhim; Jhala, Ramdevsinh; Ismailov, Saidjon; Mokhtarian, Ali
The accurate prediction of the rheological properties of nanofluids is critical for optimizing their application in various industrial systems. This study focuses on the dynamic viscosity prediction of MWCNT-Al2O3/water (80 %) and ethylene glycol (20 %) hybrid nanofluid using machine learning approaches. A multilayer perceptron neural network (MLPNN) was employed for viscosity prediction, and its structural and training parameters, including the number of hidden layers and neurons, learning rate, training technique, and transfer functions, were optimized using three metaheuristic algorithms: Genetic Algorithm (GA), Particle Swarm Optimization (PSO), and Marine Predators Algorithm (MPA). A dataset containing viscosity measurements influenced by nanoparticle volume fraction (VF), temperature (T), and shear rate (SR) was utilized. The optimization algorithms were evaluated over 10 and 20 runs for single-hidden-layer (1HL) and double-hidden-layer (2HL) MLPNNs, respectively. For the 1HL-MLPNN models, all three algorithms achieved nearly identical performance with high predictive accuracy (R = 0.99992, MSE = 0.00176). In contrast, for 2HL-MLPNN models, PSO outperformed MPA and GA with R = 0.99995 and MSE = 0.00105, followed by MPA (R = 0.99995, MSE = 0.00123) and GA (R = 0.99992, MSE = 0.00160). Also, sensitivity analysis revealed the VF as the most significant input parameter affecting viscosity predictions, followed by shear rate and temperature. These findings demonstrate the potential of metaheuristic-optimized MLPNNs for high-accuracy prediction of hybrid nanofluid rheological properties, facilitating improved design and application in thermal management systems.
Adaptation of an Activity Theory Framework for Effective Online Learning Experiences: Bringing Cognitive Presence, Teaching Presence, and Social Presence to Online Courses
(The Online Learning Consortium, 2023) Gogus,A.
Offering online courses can be seen as a way of enhancing the three essential “presences” (teaching, cognitive, and social) of the Community of Inquiry (CoI) model. Creating and enhancing cognitive, teaching, and social presences require an innovation for teachers during planning, implementing, and evaluating their online courses. As teachers develop their own expertise in teaching online, they contribute to the enhancement of cognitive, teaching, and social presences for effective online learning. The present conceptual study provides a review of the models presented previously and develops a complete model for effective online learning experience by adapting the Activity Theory within the context of online learning management. The study discusses a framework developed to adapt the Activity Theory for the design, development, implementation, and evaluation of online courses to enhance the cognitive, teaching, and social presences within complex cognitive tasks so that the learning outcomes of the course, as well as the required qualifications of higher education, can be reached. © 2023, The Online Learning Consortium. All rights reserved.
Adaptation of an Activity Theory Framework for Effective Online Learning Experiences: Bringing Cognitive Presence, Teaching Presence, and Social Presence to Online Courses
(online Learning Consortium, 2023) Gogus, Aytac
Offering online courses can be seen as a way of enhancing the three essential "presences" (teaching, cognitive, and social) of the Community of Inquiry (CoI) model. Creating and enhancing cognitive, teaching, and social presences require an innovation for teachers during planning, implementing, and evaluating their online courses. As teachers develop their own expertise in teaching online, they contribute to the enhancement of cognitive, teaching, and social presences for effective online learning. The present conceptual study provides a review of the models presented previously and develops a complete model for effective online learning experience by adapting the Activity Theory within the context of online learning management. The study discusses a framework developed to adapt the Activity Theory for the design, development, implementation, and evaluation of online courses to enhance the cognitive, teaching, and social presences within complex cognitive tasks so that the learning outcomes of the course, as well as the required qualifications of higher education, can be reached.
An adaptive algorithm for numerically solving fractional partial differential equations using Hermite wavelet artificial neural networks
(Elsevier, 2024) Ali, Amina; Senu, Norazak; Wahi, Nadihah; Almakayeel, Naif; Ahmadian, Ali
This study aims to develop a new strategy for solving partial differential equations with fractional derivatives (FPDEs) using artificial neural networks (ANNs). Numerical solutions to FPDEs are obtained through the Hermite wavelet neural network (HWNN) model. The Caputo fractional derivative is consistently applied throughout the research to address fractional -order partial differential problems. To enhance computational efficiency and expand the input pattern, the hidden layer is removed. A neural network (NN) model featuring a feed -forward architecture and error -back propagation without supervision is employed to optimize network parameters and minimize errors. Numerical illustrations are presented to demonstrate the effectiveness of this approach in preserving computational efficiency while solving FPDEs.

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