Okan Üniversitesi / Okan University

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Citation Count: 0
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; Genetik ve Biyomühendislik / Genetic and Bio-Engineering
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.
Citation Count: 1
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.
Citation Count: 3
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.; Periodontoloji / Periodontology
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.
Citation Count: 0
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; Endodonti / Endodontics
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.
Citation Count: 11
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.
Citation Count: 5
Academic domains as political battlegrounds: A global enquiry by 99 academics in the fields of education and technology
(Sage Publications Ltd, 2017) Al Lily, Abdulrahman E.; Foland, Jed; Stoloff, David; Gogus, Aytac; Erguvan, Inan Deniz; Awshar, Mapotse Tome; Schrader, P. G.; Eğitim Bilimleri / Educational Sciences
This article theorizes the functional relationship between the human components (i.e., scholars) and non-human components (i.e., structural configurations) of academic domains. It is organized around the following question: in what ways have scholars formed and been formed by the structural configurations of their academic domain? The article uses as a case study the academic domain of education and technology to examine this question. Its authorship approach is innovative, with a worldwide collection of academics (99 authors) collaborating to address the proposed question based on their reflections on daily social and academic practices. This collaboration followed a three-round process of contributions via email. Analysis of these scholars' reflective accounts was carried out, and a theoretical proposition was established from this analysis. The proposition is of a mutual (yet not necessarily balanced) power (and therefore political) relationship between the human and non-human constituents of an academic realm, with the two shaping one another. One implication of this proposition is that these non-human elements exist as political actors', just like their human counterparts, having agency' - which they exercise over humans. This turns academic domains into political (functional or dysfunctional) battlefields' wherein both humans and non-humans engage in political activities and actions that form the identity of the academic domain. For more information about the authorship approach, please see Al Lily AEA (2015) A crowd-authoring project on the scholarship of educational technology. Information Development. doi: 10.1177/0266666915622044.
Citation Count: 1
Academic Writing in a Global Context: The Politics and Practices of Publishing in English
(Tesol, 2012) Yigitoglu, Nur
[No Abstract Available]
Citation Count: 7
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; İnşaat Mühendisliği / Civil Engineering
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.
Citation Count: 2
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.
Citation Count: 21
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.
Citation Count: 21
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.
Citation Count: 1
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; Eğitim Bilimleri / Educational Sciences
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.
Citation Count: 0
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.
Citation Count: 0
An advanced scheme based on artificial intelligence technique for solving nonlinear riccati systems
(Springer Heidelberg, 2024) Admon, Mohd Rashid; Senu, Norazak; Ahmadian, Ali; Majid, Zanariah Abdul
Recently, one artificial intelligence technique, known as artificial neural network (ANN), has brought advanced development to the arena of mathematical research. It competes effectively with other traditional methods in providing accurate solutions for fractional differential equations (FDEs). This work aims to implement a feedforward ANN with two hidden layers to solve nonlinear systems based on the fractional Riccati differential equation (FRDE). The network parameters are trained using the Adam optimization method with the aid of automatic differentiation. A vectorization algorithm is designated for the selected step to make the computation process more efficient. Two different initial value problems in integer-order derivatives and fractional-order derivatives are discussed. Numerical results demonstrate that the proposed method not only closely matches the exact solutions and reference solutions but also is more accurate than other existing methods.
Citation Count: 0
Advancements in MXenes and mechanochemistry: exploring new horizons and future applications
(Royal Society of Chemistry, 2024) Iravani, S.; Zarepour, A.; Nazarzadeh Zare, E.; Makvandi, P.; Khosravi, A.; Varma, R.S.; Zarrabi, A.; Genetik ve Biyomühendislik / Genetic and Bio-Engineering
MXenes, a class of two-dimensional (2D) materials derived from transition metal carbides, nitrides, and carbonitrides, have garnered significant attention due to their unique properties and potential applications in various fields, including energy storage, catalysis, and electronics. Mechanochemistry, the study of chemical reactions driven by mechanical forces, offers a novel approach to synthesize and manipulate MXenes, enhancing their properties and expanding their functional applications. This review explores the intersection of MXenes and mechanochemistry, highlighting recent advancements in the mechanochemical synthesis of MXenes and their derivatives. We discuss the mechanisms underlying the mechanochemical processes, including the role of shear forces, ball milling, and other mechanical techniques in facilitating the exfoliation and functionalization of MXenes. Furthermore, we examine the impact of mechanochemical methods on the structural integrity, surface chemistry, and electronic properties of MXenes, which are crucial for their performance in applications such as supercapacitors, batteries, and sensors. This review also addresses the challenges and limitations associated with mechanochemical approaches, including scalability and reproducibility, while proposing future directions for research in this promising field. By integrating mechanochemistry with MXene research, we aim to provide insights into innovative strategies for the development of advanced materials that can meet the demands of next-generation technologies. This synthesis of knowledge not only underscores the versatility of MXenes but also emphasizes the transformative potential of mechanochemistry in materials science. © 2024 RSC.
Citation Count: 0
Advancing personalized medicine: Integrating statistical algorithms with omics and nano-omics for enhanced diagnostic accuracy and treatment efficacy
(Elsevier, 2024) Coskun, Abdurrahman; Ertaylan, Gokhan; Pusparum, Murih; Van Hoof, Rebekka; Kaya, Zelal Zuhal; Khosravi, Arezoo; Zarrabi, Ali; Genetik ve Biyomühendislik / Genetic and Bio-Engineering
Medical laboratory services enable precise measurement of thousands of biomolecules and have become an inseparable part of high-quality healthcare services, exerting a profound influence on global health outcomes. The integration of omics technologies into laboratory medicine has transformed healthcare, enabling personalized treatments and interventions based on individuals' distinct genetic and metabolic profiles. Interpreting laboratory data relies on reliable reference values. Presently, population-derived references are used for individuals, risking misinterpretation due to population heterogeneity, and leading to medical errors. Thus, personalized references are crucial for precise interpretation of individual laboratory results, and the interpretation of omics data should be based on individualized reference values. We reviewed recent advancements in personalized laboratory medicine, focusing on personalized omics, and discussed strategies for implementing personalized statistical approaches in omics technologies to improve global health and concluded that personalized statistical algorithms for interpretation of omics data have great potential to enhance global health. Finally, we demonstrated that the convergence of nanotechnology and omics sciences is transforming personalized laboratory medicine by providing unparalleled diagnostic precision and innovative therapeutic strategies.
Citation Count: 0
AI-based visual speech recognition towards realistic avatars and lip-reading applications in the metaverse
(Elsevier, 2024) Li, Ying; Hashim, Ahmad Sobri; Lin, Yun; Nohuddin, Puteri N. E.; Venkatachalam, K.; Ahmadian, Ali
The metaverse, a virtually shared digital world where individuals interact, create, and explore, has witnessed rapid evolution and widespread adoption. Communication between avatars is crucial to their actions in the metaverse. Advances in natural language processing have allowed for significant progress in producing spoken conversations. Within this digital landscape, the integration of Visual Speech Recognition (VSR) powered by deep learning emerges as a transformative application. This research delves into the concept and implications of VSR in the metaverse. This study focuses on developing realistic avatars and a lip-reading application within the metaverse, utilizing Artificial Intelligence (AI) techniques for visual speech recognition. Visual Speech Recognition in the metaverse refers to using deep learning techniques to comprehend and respond to spoken language, relying on the visual cues provided by users' avatars. This multidisciplinary approach combines computer vision and natural language processing, enabling avatars to understand spoken words by analyzing the movements of their lips and facial expressions. Key components encompass the collection of extensive video datasets, the employment of 3D Convolutional Neural Networks (3D CNNs) combined with ShuffleNet and Densely Connected Temporal Convolutional Neural Networks (DC-TCN) called (CFS-DCTCN) to model visual and temporal features, and the integration of contextual understanding mechanisms. The two datasets Wild (LRW) dataset and the GRID Corpus datasets are utilized to validate the proposed model. As the metaverse continues its prominence, integrating Visual Speech Recognition through deep learning represents a pivotal step towards forging immersive and dynamic virtual worlds where communication transcends physical boundaries. This paper contributes to the foundation of technology-driven metaverse development and fosters a future where digital interactions mirror the complexities of human communication. The proposed model achieves 99.5 % on LRW and 98.8 % on the GRID dataset.
Citation Count: 5
Alkali-silica reaction of sanitary ware ceramic wastes utilized as aggregate in ordinary and high-performance mortars
(Elsevier Ltd, 2022) Tutkun,B.; Beglarigale,A.; Yazici,H.; İnşaat Mühendisliği / Civil Engineering
Waste management has been the foremost concern in the last decades. Utilizing sanitary ware ceramic (SWC) wastes in concrete has been found to be beneficial in terms of sustainability and cost in previous studies; however, deleterious alkali-silica reaction (ASR) potential of this waste aggregate, albeit it's high SiO2 content, has not been taken into account. This study aims to examine ASR potential of SWC wastes as well as the effects of permeability, w/c ratio, and reactive powder content of mixtures on the ASR-induced expansions in detail. Accelerated mortar bar, total and capillary water absorptions, and chloride ion penetration tests were conducted for %20, %40, %60, %80, and %100 replacement ratios at the first part of the study. The SWC aggregate showed ASR-induced expansions in “pessimum proportions”. With a 9-day delay, similar patterns (trends) of ASR expansions were observed in the mixtures with a w/c ratio of 0.3 as compared with those of 0.5 w/c ratio. While the ASR expansions had meaningful relations with the water absorption tests and w/c ratio, there was no noteworthy correlation with the rapid chloride ion penetration test results, since the SWC aggregate effected the properties of pore solution. The effect of the finer grains of the SWC aggregate on ASR was investigated in the second part of the study. For this purpose, the SWC aggregate finer than 250 µm was replaced with same sized limestone aggregate. The results revealed that the finer grains of SWC aggregate were responsible for the reductions observed in the first part of the study not due to “pessimum effect” phenomenon but rather to the pozzolanic activity of the finer grains. © 2021
Citation Count: 4
Alkali-silica reaction of sanitary ware ceramic wastes utilized as aggregate in ordinary and high-performance mortars
(Elsevier Sci Ltd, 2022) Tutkun, Bayram; Beglarigale, Ahsanollah; Yazici, Halit; İnşaat Mühendisliği / Civil Engineering
Waste management has been the foremost concern in the last decades. Utilizing sanitary ware ceramic (SWC) wastes in concrete has been found to be beneficial in terms of sustainability and cost in previous studies; however, deleterious alkali-silica reaction (ASR) potential of this waste aggregate, albeit it's high SiO2 content, has not been taken into account. This study aims to examine ASR potential of SWC wastes as well as the effects of permeability, w/c ratio, and reactive powder content of mixtures on the ASR-induced expansions in detail. Accelerated mortar bar, total and capillary water absorptions, and chloride ion penetration tests were conducted for %20, %40, %60, %80, and %100 replacement ratios at the first part of the study. The SWC aggregate showed ASR-induced expansions in "pessimum proportions". With a 9-day delay, similar patterns (trends) of ASR expansions were observed in the mixtures with a w/c ratio of 0.3 as compared with those of 0.5 w/c ratio. While the ASR expansions had meaningful relations with the water absorption tests and w/c ratio, there was no noteworthy correlation with the rapid chloride ion penetration test results, since the SWC aggregate effected the properties of pore solution. The effect of the finer grains of the SWC aggregate on ASR was investigated in the second part of the study. For this purpose, the SWC aggregate finer than 250 mu m was replaced with same sized limestone aggregate. The results revealed that the finer grains of SWC aggregate were responsible for the reductions observed in the first part of the study not due to "pessimum effect" phenomenon but rather to the pozzolanic activity of the finer grains.
Citation Count: 5
Altered methyltetrahydrofolate reductase gene polymorphism in mothers of children with attention deficit and hyperactivity disorder
(Pergamon-elsevier Science Ltd, 2019) Baykal, Saliha; Batar, Bahadir; Nalbantoglu, Aysin; Albayrak, Yakup; Hanci, Halil; Potas, Nihan; Karabekiroglu, Koray
Attention Deficit and Hyperactivity Disorder (ADHD) is one of the most common psychiatric disorders in childhood and causes significant functional impairments in children. Behavioral genetic and molecular genetic studies have provided significant evidence in terms of highlighting the etiology of ADHD. Folate deficiency during pregnancy is an established risk factor for ADHD. Polymorphisms in the Methyltetrahydrofolate Reductase (MTHFR) encoding gene, such as A1298C and C667T, are associated with the decreased bioavailability of folate, and this condition can act like folate deficiency. In the literature, no study has investigated MTHFR polymorphisms in mothers of children with ADHD. Sixty-four children diagnosed with ADHD and their mothers as well as 40 healthy children and their mothers participated in this study. MTHFR polymorphisms were investigated in all participants. Comparison of the C677C and A1298C MTHFR polymorphisms in children with and without ADHD revealed no significant differences. We found that the maternal C677C_CT genotype counts, both observed and expected values, were significantly different from those based on Hardy-Weinberg Principle Analysis in the ADHD group. The most important result of this study was that maternal C677C MTHFR gene polymorphisms are significant risk factors in for ADHD, and we argue that children with ADHD are exposed to folate deficiency, even if their mothers received a sufficient amount of folate during pregnancy. This result also highlights one of the genetic factors of ADHD. Further studies should be performed to confirm this finding.

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