Scopus İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/395
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Article Citation - WoS: 38Citation - Scopus: 38pH- and Temperature-Responsive Amphiphilic Diblock Copolymers of 4-Vinylpyridine and Oligoethyleneglycol Methacrylate Synthesized by RAFT Polymerization(Elsevier Sci Ltd, 2014-01) Topuzogullari, Murat; Bulmus, Volga; Dalgakiran, Eray; Dincer, SevilDiblock copolymers of 4-vinylpyridine (4VP) and oligoethyleneglycol methyl ether methacrylate (OEGMA) were synthesized for the first time using RAFT polymerization technique as potential drug delivery systems. Effects of the number of ethylene glycol units in OEGMA, chain length of hydrophobic P4VP block, pH, concentration and temperature on the solution behavior of the copolymers were investigated comprehensively. Copolymer chains formed micelles at pH values higher than 5 whereas unimeric polymers were observed to exist below pH 5, owing to the repulsion between positively charged P4VP blocks. The size of the micelles was dependent on the relative length of blocks, P4VP and POEGMA. Thermo-responsive properties of copolymers were investigated depending on the pH and length of P4VP block. The increase in the length of P4VP block decreased the LCST substantially at pH 7. At pH 3, LCST of copolymers shifted to higher temperatures due to the increased interaction of copolymers with water through positively charged P4VP block. (C) 2013 Elsevier Ltd. All rights reserved.Article Citation - WoS: 42Citation - Scopus: 57What Are the Key Success Factors for Strategy Formulation and Implementation? Perspectives of Managers in the Hotel Industry(Elsevier Sci Ltd, 2020-08) Koseoglu, Mehmet Ali; Altin, Mehmet; Chan, Eric; Aladag, Omer FarukThis study investigates how hotel managers describe strategy and identify key success factors for its formulation and implementation. The study analyzes qualitative data collected through semi-structured interviews with property level top managers of hotels in Hong Kong. The findings show that hotel managers prioritize competition analysis and macro-environmental conditions over internal characteristics such as teamwork in strategy formulation. In the implementation phase, however, internal considerations such as employee involvement and strategic consensus are given prominence. This study provides a significant contribution by examining how top level practitioners in the industry interpret success factors in their strategic management efforts, and it highlights a largely neglected area in the hospitality and tourism management literature.Article Citation - WoS: 24Citation - Scopus: 33Variable Structure Controllers for Unstable Processes(Elsevier Sci Ltd, 2015-08) Ablay, GunyazA variable structure control (VSC) method for unstable industrial processes is proposed. The proposed control method is able to provide a highly satisfactory system performance and to tackle with robustness issues of the processes in the presence of uncertainties. An ITAE-based numerical tuning algorithm for acquiring optimal control parameters, and a direct auto-tuning mechanism for the proposed controller are also provided. The performance of the proposed VSC method is illustrated on some unstable process models including a continuous stirred tank reactor (CSTR), in order to show its effectiveness, validity and feasibility. (C) 2015 Elsevier Ltd. All rights reserved.Article Citation - WoS: 23Citation - Scopus: 28Ultra-Rapid Catalytic Degradation of 4-Nitrophenol With Ionic Liquid Recoverable and Reusable Ibuprofen Derived Silver Nanoparticles(Elsevier Sci Ltd, 2018-06) Hassan, Syeda Sara; Carlson, Krista; Mohanty, Swomitra Kumar; Sirajuddin; Canlier, AliThis study reports a one-pot and eco-friendly method for the synthesis of spherical ibuprofen derived silver nanoparticles (IBU-AgNPs) in aqueous media using ibuprofen analgesics drug as capping as well as reducing agent. Formation of AgNPs occurred within a few min (less than 5 min) at room temperature without resorting to any harsh conditions and hazardous organic solvents. Synthesized AgNPs were characterized with common analytical techniques. Transmission electron microscope (TEM) images confirmed the formation of spherical particles having a size distribution in the range of 12.5 +/- 1.5 nm. Employment of IBU analgesic aided the control of better size distribution and prevented agglomeration of particles. Such AgNPs solution was highly stable for more than two months when stored at ambient temperature. The IBU-AgNPs solution showed excellent ultra-rapid catalytic activity for the complete degradation of toxic 4-nitrophenol (4-NPh) into non-toxic 4-aminophenol (4-APh) within 40 s. AgNPs were recovered with the help of water insoluble-room temperature ionic liquid and reused with enhanced catalytic potential. This method provides a novel, rapid and economical alternative for the treatment of toxic organic pollutants to maintain water quality and environmental safety against water pollution. It is extendable for the control of other reducible contaminants in water as well. Furthermore, this catalytic activity for an effective degradation of organic toxins is expected to play a crucial role for achieving the Sustainable Development Goal 6 set by United Nations. (C) 2017 Elsevier Ltd. All rights reserved.Article Citation - WoS: 135Citation - Scopus: 163Thermal Conductivity, Compressive Strength and Ultrasonic Wave Velocity of Cementitious Composite Containing Waste PET Lightweight Aggregate (WPLA)(Elsevier Sci Ltd, 2013-02) Akcaozoglu, Semiha; Akcaozoglu, Kubilay; Atis, Cengiz DuranIn this study, the influence of waste PET as lightweight aggregate (WPLA) replacement with conventional aggregate, on thermal conductivity, unit weight and compressive strength properties of concrete composite was investigated. For this purpose, five different mixtures were prepared (the control mixtures and four WPLA mixtures including 30%, 40%, 50%, and 60% waste PET aggregate by volume). Thermal conductivity (TC) coefficients of the specimens were measured with guarded hot plate apparatus according to TS ISO 8302 [1]. The thermal conductivity coefficient, unit weight and compressive strength of specimens decreased as the amount of WPLA increased in concrete. The minimum thermal conductivity value was 0.3924 W/m K, observed at 60% WPLA replacement. From this result, it was concluded that waste PET aggregates replacement with conventional aggregate in the mixture showed better insulation properties (i.e. lower thermal coefficient). Due to the low unit weight and thermal conductivity values of WPLA composites, there is a potential of using WPLA composites in construction applications. (c) 2012 Elsevier Ltd. All rights reserved.Article Citation - WoS: 19Citation - Scopus: 23The Effects of Aerobic/Anoxic Period Sequence on Aerobic Granulation and COD/N Treatment Efficiency(Elsevier Sci Ltd, 2013-11) Ersan, Yusuf Cagatay; Erguder, Tuba HandeThe effects of period sequence (anoxic-aerobic and aerobic-anoxic) on aerobic granulation from suspended seed sludge, and COD, N removal efficiencies were investigated in two sequencing batch reactors. More stable granules with greater sizes (1.8-3.5 mm) were developed in R1 (anoxic-aerobic sequence). Yet, no significant difference was observed between the reactors in terms of removal efficiencies. Under optimum operational conditions, 92-95% COD, 89-90% TAN and 38-46% total nitrogen removal efficiencies were achieved. The anoxic-aerobic period sequence (R1) resulted in almost complete denitrification during anoxic periods while aerobic-anoxic sequence (R2) led to nitrate accumulation due to limited-carbon source and further granule disintegration. NH3-N concentration of 15-28 mg/L was found to inhibit COD removal up to 30%. This study also revealed the inhibitory sulfide production during anoxic periods. Sulfate concentration of 52.6-70.2 mg/L was found to promote sulfate reduction and sulfide generation (0.24-0.62 mg/L) which, together with free-ammonia, inhibited TAN oxidation by 10-50%. (C) 2013 Elsevier Ltd. All rights reserved.Article Citation - WoS: 86Citation - Scopus: 104The Analysis of 'Financial Resource Curse' Hypothesis for Developed Countries: Evidence from Asymmetric Effects With Quantile Regression(Elsevier Sci Ltd, 2020-10) Dogan, Eyup; Altinoz, Buket; Tzeremes, PanayiotisA vast body of literature either proxies natural resource abundance with total rents or focuses on the natural resource curse hypothesis. Furthermore, most empirical studies in the literature use traditional estimation methods. To fill the mentioned gaps, this study investigates the financial resource curse hypothesis by using the linkage between financial development and four natural resource rents (oil rents, coal rents, forest rents and natural gas rents) and applying the panel quantile regression with fixed effects on a dataset for a group of developed countries. This study finds that oil rents, coal rents, forest rents and natural gas rents have a positive effect on financial development, which supports financial resource blessing against financial resource curse for developed countries. In addition, a robust examination is conducted by applying the Canay two-step framework. The outcomes verify the main findings although the incremental effect on financial development of forest rents is greater than the other three proxies. This situation can be described as critical for the sustainability of developments related to natural resource rents in financial development and new set of suggestions can be made for policymakers.Article Citation - WoS: 57Citation - Scopus: 69Synchrosqueezing Transform Based Feature Extraction From EEG Signals for Emotional State Prediction(Elsevier Sci Ltd, 2019-07) Ozel, Pinar; Akan, Aydin; Yilmaz, BulentThis paper presents a novel method for emotion recognition based on time-frequency analysis using multivariate synchrosqueezing transform (MSST) of multichannel electroencephalography (EEG) signals. With the advancements of the multichannel sensor applications, the need for multivariate algorithms has become obvious for extracting features that stem from multichannel dependency in addition to mono-channel features. In order to model the joint oscillatory structure of these multichannel signals, MSST has recently been proposed. It uses the concepts of joint instantaneous frequency and bandwidth. Electrophysiological data processing mostly requires joint time-frequency analysis in addition to both time and frequency analysis separately. The short-time Fourier transform (STFT) and wavelet transform (WT) are the main approaches utilized in time-frequency analysis. In this paper, the feasibility and performance of multivariate wavelet-based synchrosqueezing algorithm was demonstrated on EEG signals obtained from publically available DEAP database by comparing with its univariate version. Eight emotional states were considered by combining arousal-valence and dominance dimensions. Using linear support vector machines (SVM) as a classifier, MSST and its univariate version resulted in the highest prediction accuracy rates of (9) over tilde3% among all emotional states. (C) 2019 Elsevier Ltd. All rights reserved.Article Citation - WoS: 34Citation - Scopus: 45Strategy Implementation Research in Hospitality and Tourism: Current Status and Future Potential(Elsevier Sci Ltd, 2020-07) Aladag, Omer Faruk; Koseoglu, Mehmet Ali; King, Brian; Mehraliyev, FuadTo achieve their business objectives, hospitality and tourism organizations need effective implementation as well as consistent strategy formulation. However, the implementation aspect of strategy has attracted relatively less scholarly interest than strategic planning despite its critical role in achieving performance outcomes. Consequently, it is timely to provide an in-depth analysis of the strategy implementation literature. This is particularly the case in hospitality and tourism management where comprehensive literature reviews of strategy implementation have been lacking. To address the knowledge gap, the authors conduct a systematic literature review of 139 articles that appeared in 42 journals over the period 1988-2019. The items were grouped into six topic clusters with a view to generating novel research questions that have the potential to advance the field. We identify four main gaps that should be addressed and suggest prospective research directions.Article Citation - WoS: 32Citation - Scopus: 32Revisiting the Nexus Among Carbon Emissions, Energy Consumption and Total Factor Productivity in African Countries: New Evidence from Nonparametric Quantile Causality Approach(Elsevier Sci Ltd, 2020-03) Dogan, Eyup; Tzeremes, Panayiotis; Altinoz, BuketThis study aims to contribute to the existing thin body of nonlinear causality literature by applying the new hybrid nonparametric quantile causality approach. In this line, we investigate the non-linear nexus among total factor productivity, energy consumption and carbon emissions for seventeen African countries. From the results, it is remarkable that there are generally strong causalities between the variables in the middle lower, middle upper and middle quantiles. Hence, energy consumption, environmental pollution and total factor productivity are closely linked in African countries. In particular, bidirectional linkage is detected between total factor productivity and energy consumption for Angola, Benin, Botswana, Cote d'Ivoire, Kenya, Morocco, Egypt, Nigeria and Tunisia. Studying the relationship between total factor productivity and emissions again at the middle quantile bidirectional causal ordering is documented almost for all the countries. Lastly and regarding the linkage between energy consumption and carbon emissions, a strong bidirectional ordering between the two variables is confirmed for Angola, Benin, Cote d'Ivoire, Cameroon, Kenya, Morocco, Egypt, Mozambique, Nigeria, Senegal and Tunisia. We can notice that an increase in economic development is critical for these countries; a number of regulatory policies for environmental problems and energy consumption are required during this development.