Allı, Abdulkadir | Şanal, Timur | Hazer, Baki

Article | 2015 | Turkish Journal of Chemistry39 ( 2 ) , pp.382 - 394

Abstract: Water soluble hydroxylated soya oil polymer was used in the redox polymerization of N-isopropylacrylamide (NIPAM) in order to obtain water-based hydroxylated-soya oil polymer-g-PNIPAM graft copolymer. For this purpose, soya oil was exposed to air under sunlight to obtain autoxidized soya oil polymer (PSy-ox). PSy-ox was allowed to react with diethanol amine to obtain hydroxylated soya oil polymer (hydroxylated-PSy). An ammonium persulfate with hydroxylated-PSy redox initiating system was used in the polymerization of NIPAM in order to obtain thermo-responsive hydroxylated-PSy-g-PNIPAM water-based graft copolymers. The graf . . .t copolymers were characterized using proton nuclear magnetic resonance, Fourier transform infrared~spectroscopy, gel permeation chromatography, thermal gravimetric analysis, and differential scanning calorimetry techniques. The effects of hydroxylated-PSy on the thermal response rate of PNIPAM and the percentage of transmittance in the water of graft copolymers were studied by means of observing UV transmittance behaviors in response to changing temperature. This showed the temperature-responsive property, and exhibited a volume phase transition from 22 °C to 29 °C, while that of PNIPAM was 32 °C. Abstract: Water soluble hydroxylated soya oil polymer was used in the redox polymerization of N-isopropylacrylamide (NIPAM) in order to obtain water-based hydroxylated-soya oil polymer-g-PNIPAM graft copolymer. For this purpose, soya oil was exposed to air under sunlight to obtain autoxidized soya oil polymer (PSy-ox). PSy-ox was allowed to react with diethanol amine to obtain hydroxylated soya oil polymer (hydroxylated-PSy). An ammonium persulfate with hydroxylated-PSy redox initiating system was used in the polymerization of NIPAM in order to obtain thermo-responsive hydroxylated-PSy-g-PNIPAM water-based graft copolymers. The graft copolymers were characterized using proton nuclear magnetic resonance, Fourier transform infrared~spectroscopy, gel permeation chromatography, thermal gravimetric analysis, and differential scanning calorimetry techniques. The effects of hydroxylated-PSy on the thermal response rate of PNIPAM and the percentage of transmittance in the water of graft copolymers were studied by means of observing UV transmittance behaviors in response to changing temperature. This showed the temperature-responsive property, and exhibited a volume phase transition from 22 °C to 29 °C, while that of PNIPAM was 32 °C Daha fazlası Daha az

Biswas, Chandra Sekhar | Hazer, Baki

Article | 2015 | COLLOID AND POLYMER SCIENCE293 ( 1 ) , pp.143 - 152

Macroporous poly(N-ethylacrylamide) (PNEAM) hydrogels have been prepared in a methanol-water (1:1, v/v) mixture in the presence of 0, 0.05, 0.1, 0.15, and 0.2 M yttrium trifluoromethanesulfonate [Y(OTf)(3)] Lewis acid (LA) concentrations. SEM micrographs show that the resulted hydrogels are highly porous. Swelling ratios of all the hydrogels in water decrease with the increase in the temperature, and the hydrogels show lower critical solution temperature (LCST) volume phase transition at around 75 A degrees C. LCST of PNEAM homopolymers gradually increases with the increase in the isotacticity of the polymers. Moreover, the hydrogel . . .s show cononsolvency in different methanol-water mixtures at 50 A degrees C. Deswelling rate of the hydrogels prepared in the presence of LA is higher than the gel prepared in the absence of LA and this rate increases with increase in the LA concentration. The reswelling rate of the hydrogels also follows the same order, that is reswelling rate also increases with the increase in the LA loading in the gels. All these results are explained on the basis of the formation of the highly porous hydrogels with a higher isotactic PNEAM chain segment in a methanol-water mixture in the presence of LA Daha fazlası Daha az

Yılmaz, Ergin | Baysal, Veli | Özer, Mahmut

Article | 2015 | Physics Letters, Section A: General, Atomic and Solid State Physics379 ( 26-27 ) , pp.1594 - 1599

We investigate the effects of time-periodic coupling strength on the temporal coherence or firing regularity of a scale-free network consisting of stochastic Hodgkin-Huxley (H-H) neurons. The temporal coherence exhibits a resonance-like behavior depending on the cell size or the channel noise intensity. The best temporal coherence requires an optimal channel noise intensity, and this coherence can be significantly increased by time-periodic coupling strength when its frequency matches the integer multiples of the intrinsic subthreshold oscillation frequency of H-H neuron. Particularly, we find the multiple-coherence resonance depend . . .ing on frequency of time-periodic coupling strength at the optimal noise intensity. We also obtain a resonance-like dependence of temporal coherence on the amplitude of time-periodic coupling strength. Additionally, we investigate the effects of average degree on the temporal coherence and find that the temporal coherence exhibits a resonance-like behavior with respect to the network average degree, indicating that the best regularity requires an optimal average degree. © 2015 Elsevier B.V. All rights reserved Daha fazlası Daha az

Genç, Ayten | Bakırcı, Büşra

Article | 2015 | Water Science and Technology71 ( 8 ) , pp.1196 - 1202

The effect of pulsed voltage application on energy consumption during electrocoagulation was investigated. Three voltage profiles having the same arithmetic average with respect to time were applied to the electrodes. The specific energy consumption for these profiles were evaluated and analyzed together with oil removal efficiencies. The effects of applied voltages, electrode materials, electrode configurations, and pH on oil removal efficiency were determined. Electrocoagulation experiments were performed by using synthetic and real wastewater samples. The pulsed voltages saved energy during the electrocoagulation process. In cont . . .inuous operation, energy saving was as high as 48%. Aluminum electrodes used for the treatment of emulsified oils resulted in higher oil removal efficiencies in comparison with stainless steel and iron electrodes. When the electrodes gap was less than 1 cm, higher oil removal efficiencies were obtained. The highest oil removal efficiencies were 95% and 35% for the batch and continuous operating modes, respectively. © IWA Publishing 2015 Daha fazlası Daha az

Surucu, Dilek | Surucu, Murat | Koksal, Kerem | Hacıoğlu, Rıfat

Proceedings | 2015 | 2015 23rd Signal Processing and Communications Applications Conference, SIU 2015 - Proceedings , pp.1849 - 1852

In this study, we perform target detection and tracking with Unmanned Aerial Vehicle (UAV) as well as the visual command of UAV. Our goal is to develop an autopilot system to reduce the human factor in UAV's. We create a system that follows different objects, stays locked to a graphical object which is glyph that has an encryption that only we describe, and executes the mission encoded on glyph in both indoor and outdoor tests. We obtain the targeting by the angle and the dimensions of the glyph. We've obtained successful results in applied presentations. © 2015 IEEE.

Allı, Sema | Tığlı-Aydın, Rahime Seda | Allı, Abdülkadir | Hazer, Baki

Article | 2015 | JAOCS, Journal of the American Oil Chemists' Society92 ( 3 ) , pp.449 - 458

Well-defined graft copolymers based on poly(?-caprolactone) (PCL) via poly(linoleic acid) (PLina), are derived from soybean oil. Poly(linoleic acid)-g-poly(?-caprolactone) (PLina-g-PCL) and poly(linoleic acid)-g-poly(styrene)-g-poly(?-caprolactone) (PLina-g-PSt-g-PCL) were synthesized by ring-opening polymerization of ?-caprolactone initiated by PLina and one-pot synthesis of graft copolymers, and by ring-opening polymerization and free radical polymerization by using PLina, respectively. PLina-g-PCL, PLina-g-PSt-g-PCL3, and PLina-g-PSt-g-PCL4 copolymers containing 96.97, 75.04 and 80.34 mol% CL, respectively, have been investigated . . . regarding their enzymatic degradation properties in the presence of Pseudomonas lipase. In terms of weight loss, after 1 month, 51.5% of PLina-g-PCL, 18.8% of PLina-g-PSt-g-PCL3, and 38.4% of PLina-g-PSt-g-PCL4 were degraded, leaving remaining copolymers with molecular weights of 16,140, 83,220 and 70,600 Da, respectively. Introducing the PLina unit into the copolymers greatly decreased the degradation rate. The molar ratio of [CL]/[Lina] dramatically decreased, from 21.3 to 8.4, after 30 days of incubation. Moreover, reduced PCL content in PLina-g-PSt-g-PCL copolymers decreased the degradation rate, probably due to the PSt enrichment within the structure, which blocks lipase contact with PCL units. Thus, copolymerization of PCL with PLina and PSt units leads to a controllable degradation profile, which encourages the use of these polymers as promising biomaterials for tissue engineering applications. © AOCS 2015 Daha fazlası Daha az

Erkaymaz, Hande | Özer, Mahmut | Orak, İlhami Muharrem

Article | 2015 | Chaos, Solitons and Fractals77 , pp.225 - 229

The electrooculogram signals are very important at extracting information about detection of directional eye movements. Therefore, in this study, we propose a new intelligent detection model involving an artificial neural network for the eye movements based on the electrooculogram signals. In addition to conventional eye movements, our model also involves the detection of tic and blinking of an eye. We extract only two features from the electrooculogram signals, and use them as inputs for a feed-forwarded artificial neural network. We develop a new approach to compute these two features, which we call it as a movement range. The res . . .ults suggest that the proposed model have a potential to become a new tool to determine the directional eye movements accurately. © 2015 Elsevier Ltd. All rights reserved Daha fazlası Daha az

Uzuntarla, Muhammet | Yılmaz, Ergin | Wagemakers, Alexandre | Özer, Mahmut

Article | 2015 | Communications in Nonlinear Science and Numerical Simulation22 ( 01.Mar ) , pp.367 - 374

Vibrational resonance (VR) is a phenomenon whereby the response of some dynamical systems to a weak low-frequency signal can be maximized with the assistance of an optimal intensity of another high-frequency signal. In this paper, we study the VR in a heterogeneous neural system having a complex network topology. We consider a scale-free network of neurons where the heterogeneity is in the intrinsic excitability of the individual neurons. It is shown that emergence of VR in heterogeneous neuron population requires less energy than a homogeneous population. We also find that electrical coupling strength among neurons plays a key role . . . in determining the weak signal processing capacity of the heterogeneous population. Lastly, we investigate the influence of interneuronal link density on the VR and demonstrate that the energy needed to obtain the resonance grows with the increase in average degree. © 2014 Elsevier B.V Daha fazlası Daha az

Kılıç, Muhammet Samet | Korkut, Şeyda | Hazer, Baki

Article | 2015 | Materials Science and Engineering C47 , pp.165 - 171

This study describes the construction of an enzymatic fuel cell comprised of novel gold nanoparticles embedded poly(propylene-co-imidazole) coated anode and cathode. Working electrode fabrication steps and operational conditions for the fuel cell have been optimized to get enhanced power output. Electrical generation capacity of the optimized cell was tested by using the municipal wastewater sample. The enzymatic fuel cell system reached to maximum power density with 1 µg and 8 µg of polymer quantity and bilirubin oxidase on electrode surface, respectively. The maximum power output was calculated to be 5 µW cm- 2 at + 0.56 V (vs. Ag . . ./AgCl) in phosphate buffer (pH 7.4, 100 mM, 20 °C) by the addition of 15 mM of glucose as a fuel source. The optimized enzymatic fuel cell generated a power density of 0.46 µW cm- 2 for the municipal wastewater sample. Poly(propylene-co-imidazole) was easily used for a fuel cell system owing to its metallic nanoparticle content. The developed fuel cell will play a significant role for energy conversion by using glucose readily found in wastewater and in vivo mediums. © 2014 Elsevier B.V. All rights reserved Daha fazlası Daha az

Yılmaz, Ergin | Özer, Mahmut

Article | 2015 | Physica A: Statistical Mechanics and its Applications421 , pp.455 - 462

We study the effect of the delayed feedback loop on the weak periodic signal detection performance of a stochastic Hodgkin-Huxley neuron. We consider an electrical autapse characterized by its coupling strength and delay time. The stochastic Hodgkin-Huxley neuron exhibits subthreshold oscillations, and thus has an intrinsic time scale with the subthreshold oscillations. Therefore, we investigate the interplay of the subthreshold oscillations, coupling strength and delay time on the weak periodic signal detection. Results indicate that the delayed feedback either enhances or suppresses the weak signal detection depending on its param . . .eters, when compared to that without the feedback. The delayed feedback augments the weak periodic signal detection for the optimal values of the intrinsic noise and the coupling strength when the delay time is close to the integer multiples of the period of the intrinsic oscillations, due to the multiple resonance among the weak signal, the intrinsic oscillations, and the delayed feedback. We analyze the interspike interval histograms and show that the delayed feedback enhances or suppresses the weak periodic signal detection by increasing or decreasing the phase locking (synchronization) between the spiking and the weak periodic signal. We also show that an optimal phase locking is obtained when the delay time is close to the period of the intrinsic oscillations, leading a single dominant time scale in the spike trains. © 2014 Elsevier B.V. All rights reserved Daha fazlası Daha az

Hazer, Baki

Article | 2015 | Polymer Degradation and Stability119 , pp.159 - 166

Biodegradable polymers gained worldwide attention among researchers because of environmental and petroleum reserve limitation issues. In this manner, poly (3-hydroxyalkanoate)s, PHAs, are very useful materials from the point of this view. They can be easily obtained by using several bacteria from renewable substrate such as sugar, plant oils and as well as synthetic chemicals. The improvement of their mechanical properties and enhance hydrophilic character are still main challenge of the polymer scientists. Herein we report the thiol-ene photo click reactions of the unsaturated medium chain length PHAs produced by using Pseudomonas . . .oleovorans from 10-undecenoic acid, octanoic acid and/or soybean oily acids that are coded as poly(3-hydroxy undecenoate) (PHU), poly(3-hydroxy octanoate-co-undecenoate) (PHOU) and poly(3-hydroxy octanoate-co-soybean oil polymer) (PHOSy), respectively, in order to obtain their hydroxyl and carboxyl derivatives. The molecular weights of the modified PHAs obtained in this work were the same as those of the starting PHAs. Structural analysis of the PHA derivatives was performed by using 1H-, 13C, HMBC and HSQC NMR techniques. Melting and glass transitions of the hydroxyl and carboxyl derivatives of the microbial polyesters were found to be relatively higher than that of the starting unsaturated PHAs. © 2015 Elsevier Ltd. All rights reserved Daha fazlası Daha az

Altın, Süreyya | Altın, Ahmet | Kahraman, Bekir Fatih | Alemdar, Sonay | Alaydın, Elif

Article | 2015 | Fresenius Environmental Bulletin24 ( 1B ) , pp.302 - 310

In this study, the utilization of dried activated sludge for removal of Cd2+ from aqueous solution in a batch system was investigated. Initial pH, biosorbent dosage, contact time, and initial metal concentration parameters were selected to determine optimal process conditions. The bi-osorption mechanism was examined by SEM, FTIR and EDX results. The optimum conditions for Cd2+ biosorption were found to be 6.0, 120 min., 1.2 g. L-1 and 80 mg. L-1, respectively for initial pH, contact time, biosorbent dosage and initial Cd2+ concentration. Langmuir and Freundlich isotherms were used to model the biosorption equilibrium data, and it wa . . .s determined that the system followed the Langmuir isotherm, and the sorption capacity of the biosorbent was found to be 15.43 mg.g-1. Biosorption followed a pseudo-second-order rate model. Two main mechanisms of Cd2+ biosorption onto the dried activated sludge were adsorption to the C-H bonds and ion exchange with Na+, K+ and Ca2+ ions Daha fazlası Daha az