Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7148

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  • Book Part
    Citation - Scopus: 1
    A Recycling Route of Plastics Via Electrospinning: From Daily Wastes To Functional Fibers
    (Walter de Gruyter GmbH, 2019) Isık, Tuğba; Horzum,N.; Demir, Mustafa Muammer
    Since large-scale plastic production has begun in the 1940s, plastics have been produced and used globally, bringing many advantages to modern life. The consumption of plastics has increased exponentially due to their low cost, chemical resistance, lightness, durability and ability to combine with other materials. However, plastic materials represent high tonnage in urban wastes, and it is known that these plastics discarded at the end of their useful life by filling the landfill sites. Electrospinning is a well-established and versatile technique for the fabrication of submicron fibers. In addition, it is a promising approach for the recycling of waste polymers without using complex methodologies. In this chapter, utilization of electrospinning approach for the recycling of daily wastes will be discussed. The literature about the daily wastes of both synthetic materials and natural/agricultural materials will be analyzed, and the applications of these materials will be given in detail. © 2019 Walter de Gruyter GmbH, Berlin/Boston. All rights reserved.
  • Article
    Epithelial-Mesenchymal Transition as a Potential Route for Dapt Resistance in Breast Cancer Cells
    (Walter de Gruyter GmbH, 2023) Tellı, Kubra; Ozuysal, Ozden Yalcın; Telli, Kübra; Yalçın Özuysal, Özden
    Objectives: Notch is a conserved pathway involved in cell- fate determination and homeostasis. Its dysregulation plays a role in poor prognosis and drug resistance in breast cancer. Targeting Notch signaling via inhibition of the gamma- secretase complex is in the spotlight of modern cancer treat- ments. Gamma-secretase inhibitors (GSI) have shown suc- cessful clinical activity in treating cancers, yet the possible resistance mechanism remains unstudied. Modeling the resistance and understanding culprit molecular mechanisms can improve GSI therapies. Accordingly, the aim of this study is to generate and analyze GSI-resistant breast cancer cells. Methods: Gradually increasing doses of DAPT, a well-known GSI, were applied to MCF-7 breast cancer cell lines to generate resistance. Cell viability, migration and gene expressions were assessed by MTT, wound healing and qRT-PCR analyses. Results: DAPT-resistant MCF-7 cells exhibited abnormal expression of Notch receptors, Notch targets (HES1, HES5, HEY1), and epithelial-mesenchymal transition (EMT) markers (E-cadherin, ZO-1, SNAIL2, N-cadherin) to overcome the continuous increase in DAPT toxicity by increased migration through mesenchymal transition. Conclusions: This study prospects into the role of EMT in the potential resistance mechanism against DAPT treatment for breast cancer cells. Complementary targeting of EMT should be investigated further for a possible effect to potentiate DAPT’s anti-cancer effects.
  • Article
    Citation - WoS: 14
    Citation - Scopus: 13
    Investigations of Polyamide Nano-Composites Containing Bentonite and Organo-Modified Clays: Mechanical, Thermal, Structural and Processing Performances
    (Walter de Gruyter GmbH, 2021) Akar, Alinda Öykü; Yıldız, Ümit Hakan; Tayfun, Ümit
    Polyamide 6 (PA) matrix was reinforced with Na-activated bentonite, amino functional silane treated bentonite and organo-modified clays at different concentrations. The preparation of composites was carried out using melt-blending method and the test samples were prepared by injection-molding process. Mechanical, thermal, structural and processing investigations of PA based composites were reported performing via tensile, hardness, and impact tests, differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray diffraction analysis (XRD) and force measurements, respectively. According to mechanical test results, additions of fillers to PA matrix caused slight improvements for tensile strength and modulus parameters. Silane treated BNT exhibited improvement in mechanical results compared to Na-activated bentonite additions. Thermal studies revealed that decomposition and melting temperatures of PA shifted to higher values after inclusion of clay into polymer matrix. Results confirmed that organo-clay and bentonite additions with their lower filling ratios yielded enhancements for the mechanical and thermal performance of polyamide.
  • Article
    Citation - WoS: 1
    Citation - Scopus: 1
    The Impact of Visual Thinking in Medical Education
    (Walter de Gruyter GmbH, 2022) Demir, Ayşe Banu; Okuyan, Zuhal; van Eck, Alexander; Mura, Gökhan; Gönlügür, Emre; Karaca, Can; Abacıoğlu, Hakan
    Background Considering medical humanities, medicine and art are two areas that resemble each other at several features. Clinical diagnosis involves the observation, description and interpretation of information of which visual ones take an important one. The skills described are important skills in the field of visual arts, as well. Underlying a good clinical practice; clinical examination and observation skills constitute an important place. Although in several studies, these skills are shown to be improved by analyzing visual art pieces, courses intended to improve visual thinking skills are not that much common in medical faculty curriculums. Materials and methods In this article, we share our opinion about the use of visual thinking in medical education by providing preliminary reflection results of learners from the second year of medical education about the visual thinking course that we have recently started to apply in Faculty of Medicine in collaboration with Faculty of Fine Arts in Izmir University of Economics in order to improve the observational skills of learners. Results Reflection results of the learners support the view that training art-viewing skill is helpful to improve observational and descriptive skills. Conclusions Increasing interdisciplinary programs on visual thinking in medical curriculums have the potential to overcome several professional development challenges in clinics.
  • Article
    Citation - WoS: 8
    Citation - Scopus: 10
    Auditory Event-Related Potentials Demonstrate Early Cognitive Impairment in Children With Subclinical Hypothyroidism
    (Walter de Gruyter GmbH, 2019) Çatlı, Gönül; Kocaaslan Atlı, Sibel; Olgaç Dündar, Nihal; Bayazıt, Onur; Evirgen Esin, Nur; Erdoğan, Uğraş; Dündar, Bumin Nuri
    Background: The aim of this study was to examine the cognitive functions of children with subclinical hypothyroidism (SH) and healthy children with the use of auditory event-related potentials (AERPs) and neuropsychological tests. Methods: Twenty children aged between 8 and 17 wars, diagnosed with SH, and 20 age-matched healthy controls were included in this study. A classical auditory oddball paradigm was applied during the electroencephalography (EEG) recordings, and event-related potentials (ERPs) were evaluated between the 0.5- and 20-Hz frequency intervals. P1, N1, P2, N2 and P3 amplitudes and latencies were measured in Fz, FCz, Cz, CPz, Pz and Oz electrodes. Additionally, a number of neuropsychological tests evaluating the reaction time and various cognitive functions were carried out. Results: In children with SH, P3 amplitudes in FCz, Cz and CPz electrodes were significantly lower than those in controls (p <0.05). In addition to this, the P1N1 and N1P2 peak-to-peak amplitude values were also found to be smaller for children with SH than controls (p <0.05). With regard to the neuropsychological tests, no significant difference was observed between the SH and control groups on any of the cognitive test parameters, reaction time or correct response rates. Conclusions: In the present study, while children with SI I did not differ from controls with respect to their cognitive functions evaluated via neuropsychological tests, cognitive differences were detected via electrophysiological investigations. This result implies that implicit changes in cognition which are not yet overtly reflected on neuropsychological tests may be detected at an early stage in children with SH.
  • Article
    Citation - WoS: 16
    Citation - Scopus: 24
    Developing Polymer Composite-Based Leaf Spring Systems for Automotive Industry
    (Walter de Gruyter GmbH, 2018) Öztoprak, Nahit; Güneş, Mehmet Deniz; Tanoğlu, Metin; Aktaş, Engin; Eğilmez, Oğuz Özgür; Şenocak, Çiler; Kulaç, Gediz
    Composite-based mono-leaf spring systems were designed and manufactured to replace existing mono-leaf metal leaf spring in a light commercial vehicle. In this study, experimentally obtained mechanical properties of different fiber-reinforced polymer materials are presented first, followed by the description of the finite element analytical model created in Abaqus 6.12-1 (Dassault Systemes Simulia Corp., RI, US) using the obtained properties. The results from the finite element analysis are presented next and compared with actual size experimental tests conducted on manufactured prototypes. The results demonstrated that the reinforcement type and orientation dramatically influenced the spring rate. The prototypes showed significant weight reduction of about 80% with improved mechanical properties. The hybrid composite systems can be utilized for composite-based leaf springs with considerable mechanical performance.
  • Article
    Citation - WoS: 1
    Citation - Scopus: 2
    Off-Design Analysis of Transonic Bypass Fan Systems Using Streamline Curvature Through-Flow Method
    (Walter de Gruyter GmbH, 2019) Acarer, Sercan; Özkol, Ünver
    The two-dimensional streamline curvature through-flow modeling of turbomachinery is still a key element for turbomachinery preliminary analysis. Basically, axisymmetric swirling flow field is solved numerically. The effects of blades are imposed as sources of swirl, work input/output and entropy generation. Although the topic is studied vastly in the literature for compressors and turbines, combined modeling of the transonic fan and the downstream splitter of turbofan engine configuration, to the authors' best knowledge, is limited. In a prior study, the authors presented a new method for bypass fan modeling for inverse design calculations. Moreover, new set of practical empirical correlations are calibrated and validated. This paper is an extension of this study to rapid off-design analysis of transonic by-pass fan systems. The methodology is validated by two test cases: NASA 2-stage fan and GE-NASA bypass fan case. The proposed methodology is a simple extension for streamline curvature method and can be applied to existing compressor methodologies with minimum numerical effort.
  • Article
    Traveling Waves of Ddes With Rational Nonlinearity
    (Walter de Gruyter GmbH, 2016) Aslan, İsmail
    It has been found that the dynamical behavior of many complex physical systems can be properly described by nonlinear DDEs. However, in the related literature, research focusing on such equations with rational nonlinearity is rare. Hence, the present study makes an attempt to fill the existing gap. To this end, we consider two distinct DDEs with rational nonlinearity. We observed that the model equations assume three kinds of traveling wave solutions; hyperbolic, trigonometric and rational including kink-type solitary waves and singular periodic solutions. Our discussion is based on the auxiliary equation method.
  • Article
    Citation - WoS: 25
    Citation - Scopus: 26
    Isolation of Eudesmane Type Sesquiterpene Ketone From Prangos Heyniae H.duman & M.f.watson Essential Oil and Mosquitocidal Activity of the Essential Oils
    (Walter de Gruyter GmbH, 2018) Özek, Gülmira; Bedir, Erdal; Tabanca, Nurhayat; Ali, Abbas; Khan, Ikhlas A.; Duran, Ahmet; Başer, Kemal H.C.; Özek, Temel
    In the present work, an endemic species Prangos heyniae collected in four locations from Turkey was subjected to hydrodistillation in Clevenger type apparatus to obtain the essential oils (EO1-4). The gas-chromatography/mass spectrometry (GC/MS) and gas-chromatography-flame ionization detector (GC/FID) analyses showed that the EOs were rich in sesquiterpenes, germacrene D (10.3-12.1%), β-bisabolene (14.4%), kessane (26.9%), germacrene B (8.2%), elemol (3.4-46.9%), β-bisabolenal (1.4-70.7%), β-bisabolenol (8.4%) and an eudesmane type sesquiterpene (1) (16.1%) with [M+218]. This unidentified compound (1) was isolated in a rapid one-step manner with >95.0% purity using Preparative Capillary Gas Chromatography (PCGC) with an HP Innowax column connected to a Preparative Fraction Collector (PFC) system. Structure determination was accomplished from 1D- and 2D-NMR spectroscopic data which determined a new eudesmane type sesquiterpene, 3,7(11)-eudesmadien-2-one (1). Using a biting deterrent bioassay, the mean proportion not biting (PNB) values of the P. heyniae EO1-4 were 0.88 for EO1 and 0.80 for EO2 which were similar to the positive control DEET (N,N-diethyl-3-methylbenzamide). The EO3 and EO4 had lower PNB values of 0.64 and 0.44, respectively. P. heyniae EO1-4 showed good larvicidal activity at 125 and 62.5 ppm whereas EO1-3 were slightly less effective at the dose of 31.25 ppm and EO4 was not active at 31.25 ppm against 1st instar Aedes aegypti.
  • Article
    Citation - WoS: 2
    Citation - Scopus: 2
    Staphylococcus Epidermidis Adhesion on Surface-Treated Open-Cell Ti6al4v Foams
    (Walter de Gruyter GmbH, 2016) Türkan, Uğur; Güden, Mustafa; Sudağıdan, Mert
    The effect of alkali and nitric acid surface treatments on the adhesion of Staphylococcus epidermidis to the surface of 60% porous open-cell Ti6Al4V foam was investigated. The resultant surface roughness of foam particles was determined from the ground flat surfaces of thin foam specimens. Alkali treatment formed a porous, rough Na2Ti5O11 surface layer on Ti6Al4V particles, while nitric acid treatment increased the number of undulations on foam flat and particle surfaces, leading to the development of finer surface topographical features. Both surface treatments increased the nanometric-scale surface roughness of particles and the number of bacteria adhering to the surface, while the adhesion was found to be significantly higher in alkali-treated foam sample. The significant increase in the number of bacterial attachment on the alkali-treated sample was attributed to the formation of a highly porous and nanorough Na2Ti5O11 surface layer.