WoS İndeksli Yayınlar Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/394

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End date: 2019Publisher: search.filters.publisher.Elsevier Sci Ltd

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  • Article
    Citation - WoS: 38
    Citation - Scopus: 38
    pH- 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, Sevil
    Diblock 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: 24
    Citation - Scopus: 33
    Variable Structure Controllers for Unstable Processes
    (Elsevier Sci Ltd, 2015-08) Ablay, Gunyaz
    A 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: 23
    Citation - Scopus: 28
    Ultra-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, Ali
    This 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: 130
    Citation - Scopus: 157
    Thermal 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 Duran
    In 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: 19
    Citation - Scopus: 23
    The Effects of Aerobic/Anoxic Period Sequence on Aerobic Granulation and COD/N Treatment Efficiency
    (Elsevier Sci Ltd, 2013-11) Ersan, Yusuf Cagatay; Erguder, Tuba Hande
    The 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: 56
    Citation - Scopus: 69
    Synchrosqueezing Transform Based Feature Extraction From EEG Signals for Emotional State Prediction
    (Elsevier Sci Ltd, 2019-07) Ozel, Pinar; Akan, Aydin; Yilmaz, Bulent
    This 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: 118
    Citation - Scopus: 140
    Resistant Starch Type V Formation in Brown Lentil (Lens Culinaris Medikus) Starch With Different Lipids/Fatty Acids
    (Elsevier Sci Ltd, 2018-02) Okumus, Bahar Nur; Tacer-Caba, Zeynep; Kahraman, Kevser; Nilufer-Erdil, Dilara
    This study aimed to characterize the brown lentil (Lens culinaris Medikus) starch and investigate the formation of amylose-lipid complexes (Resistant Starch Type V) by the addition of different lipids/fatty acids (10%, w/w) to both raw and cooked starch samples. Resistant starch content (measured by the official method of AACCI (Method 32-40), using the resistant starch assay kit) of raw brown lentil starch (BLS) increased significantly by the additions of lipids/fatty acids, starch sample complexed with HSO (hydrogenated sunflower oil) (14.1 +/- 0.4%) being the highest. For the cooked starch/lipid complexes, more profound effect was evident (22.2-67.7%). Peak, breakdown and trough viscosity values of the amylose-lipid complexed starches were significantly lower than that of BLS (p < 0.05), while significant decreases in the setback and final viscosities were only detected in oil samples, but not in fatty acids. Each lipid in concern exerted different effects on the digestibility of starch and amylose-lipid complex formation while having no substantial differential effects on the thermal properties of starch depicted by differential scanning calorimetry (DSC). Amylose-lipid complex formation with suitable fatty acids/lipids seems a promising way of increasing resistant starch content of food formulations. Although the applications being quite uncommon yet, brown lentil seems to have potential both as a starch and also as a resistant starch source.
  • Article
    Citation - WoS: 7
    Citation - Scopus: 11
    Protein Β-Sheet Prediction Using an Efficient Dynamic Programming Algorithm
    (Elsevier Sci Ltd, 2017-10) Sabzekar, Mostafa; Naghibzadeh, Mahmoud; Eghdami, Mandie; Aydin, Zafer
    Predicting the beta-sheet structure of a protein is one of the most important intermediate steps towards the identification of its tertiary structure. However, it is regarded as the primary bottleneck due to the presence of non-local interactions between several discontinuous regions in beta-sheets. To achieve reliable long-range interactions, a promising approach is to enumerate and rank all beta-sheet conformations for a given protein and find the one with the highest score. The problem with this solution is that the search space of the problem grows exponentially with respect to the number of beta-strands. Additionally, brute force calculation in this conformational space leads to dealing with a combinatorial explosion problem with intractable computational complexity. The main contribution of this paper is to generate and search the space of the problem efficiently to reduce the time complexity of the problem. To achieve this, two tree structures, called sheet-tree and grouping-tree, are proposed. They model the search space by breaking it into sub-problems. Then, an advanced dynamic programming is proposed that stores the intermediate results, avoids repetitive calculation by repeatedly uses them efficiently in successive steps and reduces the space of the problem by removing those intermediate results that will no longer be required in later steps. As a consequence, the following contributions have been made. Firstly, more accurate beta-sheet structures are found by searching all possible conformations, and secondly, the time complexity of the problem is reduced by searching the space of the problem efficiently which makes the proposed method applicable to predict beta-sheet structures with high number of beta-strands. Experimental results on the BetaSheet916 dataset showed significant improvements of the proposed method in both execution time and the prediction accuracy in comparison with the state-of-the-art beta-sheet structure prediction methods Moreover, we investigate the effect of different contact map predictors on the performance of the proposed method using BetaSheet1452 dataset. The source code is available at http://www.conceptsgate.com/BetaTop.rar. (C) 2017 Elsevier Ltd. All rights reserved.
  • Article
    Citation - WoS: 34
    Citation - Scopus: 43
    Production of Precipitated Calcium Carbonate Particles from Gypsum Waste Using Venturi Tubes as a Carbonation Zone
    (Elsevier Sci Ltd, 2019-01) Altiner, Mahmut; Top, Soner; Kaymakoglu, Burcin; Seckin, Ismail Yigit; Vapur, Huseyin
    In this study, we investigated the production of precipitated calcium carbonate (PCC) particles from desulfurization gypsum (DG) waste using a new experimental apparatus that is divided into two main parts: carbonation and stabilization zones. The solution was circulated via a pump from the stabilization zone to the carbonation zone where different types of Venturi tube were used for the reaction of CO2 with solution to produce PCC particles. The effects of CO2 flow rate, circulation rate, and Venturi types on the properties of the produced PCC particles were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), and particle size analyses. The conductivity and pH values of the solution were monitored during the carbonation. In addition, the reactivity of selected PCC was determined to evaluate its use as a sorbent in a desulfurization unit. The experimental results indicate that the Venturi tube had a strong effect on the reaction time and properties of PCC particles. The use of a Venturi tube resulted in a decrease in the time required for producing PCC particles, which were smooth, well-crystallized, and nano-sized cubic crystals. However, when no Venturi tube was used, hollow spherical crystals formed along with cubic crystals. It was found that the reactivity of selected PCC particles produced using Venturi tube was rather higher (52x10(-4) min(-1)), indicating that the PCC can be used as a sorbent in the desulfurization unit.
  • Article
    Citation - WoS: 38
    Citation - Scopus: 41
    Ozonation Pre and Post-Treatment of Denim Textile Mill Effluents: Effect of Cleaner Production Measures
    (Elsevier Sci Ltd, 2016-11) Morali, E. Kaan; Uzal, Nigmet; Yetis, Ulku
    Denim production, which is one of the leading sub-sectors of textile industry that generates considerable amount of wastewater with high pollution load both from dyeing and finishing processes. This sub-sector is therefore to consider cleaner production opportunities for these processes to reduce its wastewater generation and pollution load. In a denim-producing plant, the wastewater treatability studies have revealed that the most technically applicable cleaner production alternatives are caustic recovery from alkaline finishing wastewaters, and reuse of indigo dyeing wastewaters via the application of membrane filtration. In the present study, impact of the changes in the final effluent quality due to the foreseen cleaner production measures were considered in reference to the evaluation of impact on ozonation treatment of the effluent from a denim-producing plant. Ozonation was applied as pretreatment to the effluent from the plant before the foreseen measures (chemical oxygen demand, COD = 2750 mg/L; color = 3950 Pt-Co), and to the simulated effluent after the foreseen measures (COD = 3100 mg/L; color = 4500 Pt-Co); and also as post-treatment to the biologically treated effluent (COD = 800 mg/L; color = 3700 Pt-Co) before the foreseen measures. When applied to the effluent before the foreseen measures as pretreatment, ozonation provided 86% color and 46% COD removal with 3240 mg/h ozone dose in 70 min. However, less satisfactory results were obtained with the wastewater after the measures; with 86% color and 31% COD removals at 3960 mg/h ozone dose in 80 min. In parallel to the decrease observed in COD removal, ozone consumption was also much higher than that for the wastewater before the cleaner production measures. The findings have indicated that the environmental benefits to be brought by cleaner production measures have to be balanced against the risks to be encountered in the treatment of the final effluent. (C) 2016 Elsevier Ltd. All rights reserved.