1359 results
Search Results
Now showing 1 - 10 of 1359
Conference Object Citation - WoS: 15Citation - Scopus: 17Numerical Modeling of Hydrogen Diffusion in Metals Accounting for Large Deformations(Pergamon-elsevier Science Ltd, 2015) Aslan, OzgurWhile the deleterious effects of hydrogen on metals and alloys are well known, the precise role of hydrogen in the underlying microscopic mechanisms is still not well understood and as of yet, the modeling attempts on hydrogen embrittlement and hydrogen induced cracking have not led to a proper method for life-time prediction. This work aims at the development of a robust numerical strategy in order to solve the non-linear coupled problem presented in the work of Anand [1]. The numerical implementation is performed for finite element method and the analysis are done to address the issue of hydrogen transport and hydrogen-embrittlement-related failures in metals. Specifically, problems related to the mechanism of hydrogen enhanced localized plasticity (HELP) is studied and macroscale shear localization phenomenon resulting from hydrogen induced material softening is considered at the phenomenological level. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.Article Citation - WoS: 16Citation - Scopus: 16Using Eye-Movement Events To Determine the Mental Workload of Surgical Residents(int Group Eye Movement Research, 2018) Dalveren, Gonca Gokce Menekse; Cagiltay, Nergiz ErcilThese days, eye-tracking is one of the promising technologies used in different fields such as aviation, arts, sports, psychology and driving for several purposes. Even though it is being used for health purposes, studies involving eye-tracking are rare in the field of endo-neurosurgery. This study aims to use this technology to promote our understanding of the effect related to computer-based instructional materials on mental workload of endo-neurosurgery residents. Four computer-based simulation scenarios are developed based on skill development requirements of endo-neurosurgery residents. Two of them were designed as general models and the other two as simulated surgical models. During these surgery procedures, in real settings, surgical residents need to use their both hands simultaneously to control the endoscope and the operational tool in a coordinated fashion. Therefore, to shed light on the participants' behaviors, these scenarios are performed with dominant-hand, non-dominant hand and, finally with both-hands using haptic interfaces. Twenty-three residents volunteered in this study. Their eye-movements were recorded while performing the scenarios. According to the results of this study, when performing the simulated surgical models, an increase in the participants' mental workload was recorded when compared to the other scenarios. Accordingly, it can be concluded that the eye-movements of surgical residents can provide insights about the anticipated level of difficulty about the skill-based tasks. This information might be very critical to properly design and organize instructional materials for endo-neurosurgery, and also to better guide and evaluate the progress of trainees in computer simulation-based skill training environments.Article Citation - WoS: 5Citation - Scopus: 6Molecular/Antigenic Mimicry and Immunological Cross-Reactivity Explains Sars-Cov Autoimmunity(Elsevier, 2025) Adiguzel, Yekbun; Bogdanos, Dimitros P.; Shoenfeld, YehudaCOVID-19 pandemic is over, but its effects on chronic illnesses remain a challenging issue. Understanding the influence of SARS-COV-2-mediated autoimmunity and overt autoimmune disease is of paramount importance, as it can provide a critical mass of information regarding both infection-mediated (and vaccination-induced) autoimmune phenomena in susceptible individuals during the disease course, and short or long-term post-disease sequelae. The high prevalence of organ and non-organ specific autoantibody positivity in patients with COVID-19 led to studies attempting to delineate the origin and the underlying mechanism responsible for their induction nature, identifying novel autoantigens, and the self-epitope sequences which could be the impetus for the initiating autoreactive responses. Herein, we provide a meticulous review of the studies reporting those mimicking sequences that have been experimentally validated, based on the assumption that molecular mimicry and immunological crossreactivity may account for autoantibody development. Most reports are based on bioinformatics approaches, and only a disproportionally small number of studies currently demonstrate immunological crossreactivity. We took the opportunity to further review and searched for the linear human epitope sequences of human, through the epitopes deposited at the Immune Epitope Database. This included an analysis of autoimmune disease as the disease data to comprehensively understand the subject matter. The critical overview of the findings underscore the urgent and immense need for further research to gain a comprehensive understanding of the mechanisms involved and the anticipated appraisal that molecular mimicry and immunological crossreactivity is indeed central to the loss of immunological tolerance during SARS-COV-2 infection.Article Citation - WoS: 4Citation - Scopus: 4Mapping the Anterolateral Ligament of the Knee: a Bibliometric Analysis(Springernature, 2025) Oktem, Hale; Jamil, Yusuf; Sever, Sinem NurBackgroundThis study aims to evaluate research trends, key contributors, and thematic focuses in research of the anterolateral ligament (ALL) of the knee. It seeks to identify future direction for studies related to long-term clinical outcomes regarding ALL's role in rotational stability, especially in the context of anterior cruciate ligament (ACL) injuries.MethodsA bibliometric analysis was conducted using the Web of Science (WoS) database, covering publications from 2012 to 2024 with the search term "anterolateral ligament". A total of 942 studies were identified. Descriptive statistics summarized publication trends, authorship, institutional contributions, and citation metrics. VOSviewer software was used to analyze co-authorship network analysis, keyword co-occurrence mapping, and total citation analysis. Yearly publication and citation trends were analyzed using WoS data. Studies addressing the ALL in other body regions were excluded. Additionally, only authors with at least one publication and one citation were considered, and documents with more than 25 authors were excluded. A total citation analysis was conducted, and 24 relevant keywords with more than 5 occurrences were identified using VOSviewer.ResultsAmong 942 publications, 707 were original articles. Research output peaked in 2017 (125 articles). Sonnery-Cottet was the leading author (75 publications), while Universidade De S & atilde;o-Paulo emerged as the top institution (57 publications). Key journals included Arthroscopy: Journal of Arthroscopic and Related Surgery (143 articles) and The American Journal of Sports Medicine (131 articles). Keywords such as "anterior cruciate ligament", "reconstruction", and "rotational stability" dominated, reflecting a focus on ACL injury management. The top ten cited studies accrued 3,86 citations, with Claes et al.'s anatomical study leading (621 citations). Of the 942 ALL-related articles in WoS, 381 focused on anatomy (11,278 citations) while 814 addressed reconstruction (17,048 citations). Keyword trends shifted from anatomical to clinical terms, with anatomy declining and stability, injury, and outcomes gaining prominence from 2021 to 2024.ConclusionsThis bibliometric analysis underscores the growing interest in ALL research, peaking between 2016 and 2017. While foundational studies on ALL anatomy and biomechanics appear saturated, future research should prioritize clinical outcomes in terms of failure rate, reoperation, the long-term efficacy of ACL-ALL reconstruction, and advancements in imaging techniques.Article Citation - WoS: 16Citation - Scopus: 21A Decision Theoretic Framework for Reliability-Based Optimal Wind Turbine Selection(Elsevier Sci Ltd, 2022) Eryilmaz, Serkan; Navarro, JorgeThe problem of choosing the optimal wind turbine for a specific site is of special importance in the design process of wind farm. Manifestly, the selection of the optimal wind turbine should depend on a certain criteria. In this paper, optimal wind turbine selection is studied in terms of the capacity factor of wind turbine generator and the Expected Energy not Supplied which is one of the most commonly used reliability indices for power systems. The latter one considers the load profile of the system and is suitable to compare different wind farm compositions while the former one completely ignores the load profile of the system. This paper presents general theoretical results that are helpful to compare performance of wind turbines and wind farms without data collection and further numerical assessment. In particular, the conditions on wind turbine characteristics and availability values of wind turbines are determined to compare wind turbines and wind farms in terms of the capacity factor and Expected Energy not Supplied.Article Citation - WoS: 148Citation - Scopus: 165Polybenzimidazole Based Nanocomposite Membranes With Enhanced Proton Conductivity for High Temperature Pem Fuel Cells(Pergamon-elsevier Science Ltd, 2017) Ozdemir, Yagmur; Uregen, Nurhan; Devrim, YilserIn this study, phosphoric acid doped PBI nanocomposite membranes were prepared by dispersion of various amounts of inorganic nanoparticles in PBI polymer followed by phosphoric acid (H3PO4) doping for high temperature proton exchange membrane fuel cells (HT-PEMFC). All of the PBI composite membranes were cast from the same FBI polymer with the same molecular weight. Titanium dioxide (TiO2), silicon dioxide (SiO2) and inorganic proton conductor zirconium phosphate (ZrP) were used as inorganic fillers. The PBI based composite membranes were characterized in terms of their acid uptake and acid leaching properties, mechanical properties, chemical stabilities in N-N Dimethylacetamide (DMAc) and impedance analyses. Thermal gravimetric analysis confirmed the improved thermal stability of the PBI composite membranes. The existence of inorganic fillers was improved the acid retention capability. Electrochemical Impedance Spectroscopy (EIS) showed that the introduction of 5 wt. % SiO2 or 5 wt. % ZrP helps to increase proton conductivity. The composite membrane with TiO2 retained low conductivity values than pristine PBI and this is a result of its non-uniform membrane structure. The highest proton conductivity of 0.200 S/cm was obtained for PBI/ZrP composite membrane with the highest value of H3PO4 doping level. Nyquist plots are drawn for all the membranes at different temperatures and the plots showed good fit with Randel's circuit. As a result the experimental results suggested that the PBI based composite membranes may be a promising electrolyte used in HT-PEMFC. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Article Citation - WoS: 10Citation - Scopus: 11Strain Engineering of Germanium Nanobeams by Electrostatic Actuation(Nature Portfolio, 2019) Ayan, Arman; Turkay, Deniz; Unlu, Buse; Naghinazhadahmadi, Parisa; Oliaei, Samad Nadimi Bavil; Boztug, Cicek; Yerci, SelcukGermanium (Ge) is a promising material for the development of a light source compatible with the silicon microfabrication technology, even though it is an indirect-bandgap material in its bulk form. Among various techniques suggested to boost the light emission efficiency of Ge, the strain induction is capable of providing the wavelength tunability if the strain is applied via an external force. Here, we introduce a method to control the amount of the axial strain, and therefore the emission wavelength, on a suspended Ge nanobeam by an applied voltage. We demonstrate, based on mechanical and electrical simulations, that axial strains over 4% can be achieved without experiencing any mechanical and/or electrical failure. We also show that the non-uniform strain distribution on the Ge nanobeam as a result of the applied voltage enhances light emission over 6 folds as compared to a Ge nanobeam with a uniform strain distribution. We anticipate that electrostatic actuation of Ge nanobeams provides a suitable platform for the realization of the on-chip tunable-wavelength infrared light sources that can be monolithically integrated on Si chips.Article Citation - WoS: 94Citation - Scopus: 104Fabrication and Characterization of Cross-Linked Polybenzimidazole Based Membranes for High Temperature Pem Fuel Cells(Pergamon-elsevier Science Ltd, 2017) Ozdemir, Yagmur; Ozkan, Necati; Devrim, YilserIn this study different types of crosslinked polybenzimidazole (PBI) membranes were compared as high temperature proton exchange membrane fuel cells (HT-PEMFC). Cross-linking of PBI was performed with different cross-linkers including bisphenol A diglycidyl ether (BADGE), ethylene glycol diglycidyl ether (EGDE), alpha-alpha'-dibromo-p-xylene (DBpX), and terephthalaldehyde (TPA). The crosslinked membranes have been characterized by thermogravimetric analysis, scanning electron microscopy, acid uptake and impedance analyses. The crosslinking of the PBI polymer matrix helps to improve the acid retention properties. PBI/BADGE presented the highest acid retention properties. Proton conductivities of the membranes were comparable to that of commercial membranes. Conductivity values up to 0.151 S.cm(-1) were obtained at 180 degrees C with PBI/DBpX membranes. Gas diffusion electrodes (GDE) were fabricated by an ultrasonic coating technique with 0.6 mg Pt.cm(-2) catalyst loading for both anode and cathode. The crosslinked membranes were tested in a single HT-PEMFC with a 5 cm(2) active area at 165 degrees C without humidification. PBI/BADGE crosslinked membranes demonstrated stability and high performance on single cell HT-PEMFC tests. The maximum power density for PBI/BADGE was determined as 0.123 W. cm(-2). As a result, the experimental results suggested that the PBI/ BADGE and PBI/DBpX cross-linked membranes are promising electrolyte options for HT-PEMFC. (C) 2017 Elsevier Ltd. All rights reserved.Article Biotechnological Preparedness for Novel Pandemics: Diagnostic Performance of IVDS Against SARS-CoV(Wiley, 2025) Kavruk, Murat; Ercan, Meltem; Borsa, Baris Ata; Ozalp, Veli Cengiz; Hernandez, Frank J.Although the COVID-19 pandemic has created many challenges and negative impacts around the world, some of which will persist into the future, its technological challenge has created a unique opportunity in a globalized world. It is a rare event that almost all of humanity to be directed towards a single goal and to try to produce solutions, but the necessity of a similar global action in the future has begun to enter the agenda again. The predictions made on the basis of countries and institutions against the possibility of a pandemic, which is defined as Disease X, are shaped by the experience of the COVID-19 pandemic. Technologically, one of the know-how we have gained in this pandemic is the performance of IVD and test systems in terms of quality and quantity. A comprehensive analysis of the products produced by combining biotechnology with different strategies has not been conducted. In this context, we have analyzed the technical preferences, limitations, and other performance parameters of IVDs and test kits that could be developed against a future Disease X. The performance parameters of 2,882 biotechnological products listed for use in the European Union have been analyzed, and areas that could be targeted for increased effectiveness have been identified. Our study is the first of its kind in this field and can serve as a guide for those who want to work on detection methods, diagnostics, and novel technologies for deployment in future pandemics.Article Citation - WoS: 11Citation - Scopus: 13Compound Markov Negative Binomial Distribution(Elsevier, 2016) Eryilmaz, SerkanLet {Y-i}(i >= 1) be a sequence of {0,1} variables which forms a Markov chain with a given initial probability distribution and one-step transition probability matrix. Define N-n to be the number of trials until the nth success ("1") in {Y-i}(i >= 1). In this paper, we study the distribution of the random variable T = Sigma(Nn)(i=1) X-i, where {X-i}(i >= 1) is a sequence of independent and identically distributed random variables having a common phase-type distribution. The distribution of T is obtained by means of phase-type distributions. (C) 2015 Elsevier B.V. All rights reserved.
