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Öğe Assessment of industrial pollution effects in coastal seawater (Northeastern Mediterranean Sea) with chemometric approach(Taylor & Francis Ltd, 2021) Yucel, Yasin; Cam, Aytac RiyadThe aim of this study was to evaluate heavy metal pollution in coastal seawater collected from industrial and non-industrial areas of Iskenderun Bay. The concentrations of heavy metals (Fe, Ni, Mn, Cr, Cu, Zn, Cd, Pb, Co and Al) in the seawater samples were determined by inductively coupled plasma optical emission spectrometry (ICP-OES). The accuracy of the methods was confirmed by certified reference materials. The relative standard deviation for the analytical procedure was better than 5%. Seasonal changing of some physicochemical parameters (temperature, pH, dissolved oxygen, electrical conductivity and total dissolved solids) in seawater samples have been investigated for the assessment of quality of coastal seawater in Iskenderun Bay. Chemometric techniques (principal component analysis, cluster analysis and correlation analysis) were used to classify of the water samples. The obtained results allowed the determination of two major clusters, reflecting the groups of unpolluted and polluted stations. On the basis of the chemometric approach, it was found that some locations were under the influence of factory contamination within the observed time period. The study showed that the use of chemometrics provides useful and promising indicators to evaluate the data.Öğe Biodiesel production from canola oil using immobilized lipase(Sila Science, 2011) Yucel, Yasin; Tekeli, YenerIn the present work, lipase (triacylglycerol hydrolase, EC 3.1.1.3) Novozyme 388 was immobilized onto celite 545 using both adsorption and covalent method. The maximum immobilization yield was obtained as 78.50% when lipase immobilized by covalent method and the highest specific activity was 5.81 U/mg protein for adsorption method. The properties of the support and immobilized derivative were evaluated by fourier transform infrared spectroscopy (FTIR). Immobilized enzyme was used for biodiesel production by transesterification of crude canola oil and methanol. Maximum methyl esters yield was obtained as 98%. Celite 545 activated with polygluturaldehyde proved to be stable after even 10 reuses with each batch of 6 h and lost little activity when was subjected to repeated use. However, the immobilized lipase without polyglutaraldehyde on support material was lost its whole activity after five repeated reuses.Öğe Biodiesel production from pomace oil by using lipase immobilized onto olive pomace(Elsevier Sci Ltd, 2011) Yucel, YasinIn the present work, microbial lipase from Thermomyces lanuginosus was immobilized by covalent binding onto olive pomace. Immobilized support material used to produce biodiesel with pomace oil and methanol. The properties of the support and immobilized derivative were evaluated by scanning electron microscopy (SEM). The maximum immobilization of T. lanuginosus was obtained as 18.67 mg/g support and the highest specific activity was 10.31 U/mg protein. The properties of immobilized lipase were studied. The effects of protein concentration, pH and buffer concentration on the immobilization and lipase activity were investigated. Biodiesel production using the immobilized lipase was realized by a three-step addition of methanol to avoid strong substrate inhibition. Under the optimized conditions, the maximum biodiesel yield was 93% at 25 degrees C in 24 h reaction. The immobilized enzyme retained its activity during the 10 repeated batch reactions. (C) 2010 Elsevier Ltd. All rights reserved.Öğe Characterization of Hatay honeys according to their multi-element analysis using ICP-OES combined with chemometrics(Elsevier Sci Ltd, 2013) Yucel, Yasin; Sultanoglu, PinarChemical characterisation has been carried out on 45 honey samples collected from Hatay region of Turkey. The concentrations of 17 elements were determined by inductively coupled plasma optical emission spectrometry (ICP-OES). Ca, K, Mg and Na were the most abundant elements, with mean contents of 219.38, 446.93, 49.06 and 95.91 mg kg(-1) respectively. The trace element mean contents ranged between 0.03 and 15.07 mg kg(-1). Chemometric methods such as principal component analysis (PCA) and cluster analysis (CA) techniques were applied to classify honey according to mineral content. The first most important principal component (PC) was strongly associated with the value of Al, B. Cd and Co. CA showed eight clusters corresponding to the eight botanical origins of honey. PCA explained 75.69% of the variance with the first six PC variables. Chemometric analysis of the analytical data allowed the accurate classification of the honey samples according to origin. (C) 2013 Elsevier Ltd. All rights reserved.Öğe Computer assisted optimization of copper sulphide thin film coating parameters on glass substrates(Elsevier, 2015) Yucel, Ersin; Yucel, Yasin; Gokhan, DidemIn this work, copper sulphide (CuS) thin films were deposited on glass substrates by chemical bath deposition method under different pH, deposition temperature, stirring speed and deposition time. The effects of process parameters, such as pH from 1.8 to 2.2, deposition temperature from 30 to 50 degrees C, stirring speed from 50 to 250 rpm and deposition time from 8 to 40 h on the band gap, were optimized by central composite design (CCD) of response surface methodology (RSM). Five-level-four-factor CCD was employed to evaluate the effects of the deposition parameters on the band gap of CuS thin films. A quadratic model was established as a functional relationship between four independent variables and the band gap. Analysis of variance revealed that the proposed model was adequate. The optimum pH, deposition temperature, stirring speed and deposition time were found to be 2.10, 44.33 degrees C, 200 rpm, and 32h, respectively. Under these conditions, the experimental band gap of CuS was observed as 2.74 eV, which was well in close agreement with predicted value (2.71 eV) by the model. (C) 2015 Elsevier B.V. All rights reserved.Öğe Computer-Assisted Optimization of Electrodeposited Hydroxyapatite Coating Parameters on Medical Alloys(Springer, 2016) Coskun, M. Ibrahim; Karahan, Ismail H.; Yucel, Yasin; Golden, Teresa D.CoCrMo bio-metallic alloys were coated with a hydroxyapatite (HA) film by electrodeposition using various electrochemical parameters. Response surface methodology and central composite design were used to optimize deposition parameters such as electrolyte pH, deposition potential, and deposition time. The effects of the coating parameters were evaluated within the limits of solution pH (3.66 to 5.34), deposition potential (-1.13 to -1.97 V), and deposition time (6.36 to 73.64 minutes). A 5-level-3-factor experimental plan was used to determine ideal deposition parameters. Optimum conditions for the deposition parameters of the HA coating with high in vitro corrosion performance were determined as electrolyte pH of 5.00, deposition potential of -1.8 V, and deposition time of 20 minutes.Öğe Deposition of PbS thin films using a continuous flow reactor: Comparison of the modified technique with conventional methods in the coating of PbS thin film on the substrate(Elsevier, 2022) Yucel, Ersin; Yucel, YasinA reactor was designed to coat the PbS thin film on glass substrate by continuous flow. A methodology is proposed to deposit PbS films based on reducing the roughness via a laminar and continuous flow in the reactor without being affected by the chaotic properties of the turbulent flow. The modified coating method was named flow-through chemical deposition (FTCD). The morphological analysis demonstrated that the surface roughness of PbS films deposited by the FTCD method was lower than the other films. The wetting behaviour of PbS surfaces is consistent with the roughness of the PbS layers coated on the substrate. The results revealed that the properties of the films were influenced from the deposition method, the substrate position and the movement of the chemical solution in the reaction medium. The developed innovative approach has shown promising results for the chemical synthesis of PbS films in the context of surface modification.Öğe Determination of heavy metals in olive fruits as an indicator of environmental pollution(Taylor & Francis Ltd, 2020) Yucel, Yasin; Kilicoglu, Abdullah LutfiCharacterization of olive fruits according to their heavy metal composition was carried out with a chemometric approach. The concentrations of Pb, Cd, Cr, Mn, Fe, Ni and Co in the olive samples were determined by high-resolution continuum source atomic absorption spectrometer (HR-CS AAS). Heavy metal contamination in twenty-three olive samples collected from different regions (industrialized and non-industrialized) of Hatay province in Turkey was evaluated. Analytical performance and reliability of the method were checked by validation parameters. The results demonstrated that the mean content of heavy metals in the olive samples were ranged between 0.046 and 17.229 mg kg(-1). The analytical data was examined by principal component analysis (PCA) and cluster analysis (CA) for the classification studies. The olive samples were classified into three groups reflecting the groups of unpolluted, industrial polluted and non-industrial polluted stations. This model can be a useful tool for the olive industry to emphasize product quality and naturalness.Öğe Determination of industrial pollution effects on citrus honeys with chemometric approach(Elsevier Sci Ltd, 2012) Yucel, Yasin; Sultanoglu, PinarThe aim of this study was to determine the levels of essential, trace and toxic elements, such as K, Ca, Fe, Cu, Al, Ni, Sn, Pb and Cd in citrus honeys from different regions (industrialized and nonindustrialized) of Hatay, Turkey. K, Ca, Na and Mg were the most abundant elements, with mean contents of 363.5, 256.6, 88.1 and 37.7 mg/kg, respectively. The trace element mean contents ranged between 0.032 and 15.58 mg/kg. Significant differences in Fe, Cu, Al, Ni, Sn, Pb, Cd, Co and Sr levels were observed between two different regions. The findings that Fe, Cu, Al. Ni, Sn, Pb, Cd, Co and Sr contents in citrus honeys from industrialized regions were higher than citrus honeys from non-industrialized regions indicate that the honeys were affected by industrial pollution. Chemometric methods were applied to classify honey according to mineral content. Cluster analysis showed three clusters corresponding to the three different regions. (c) 2012 Elsevier Ltd. All rights reserved.Öğe Effect of doping concentration on the structural, morphological and optical properties of Ca-doped PbS thin films grown by CBD(Elsevier Gmbh, Urban & Fischer Verlag, 2017) Yucel, Ersin; Yucel, YasinPure and calcium doped lead sulfide (PbS) thin films were prepared by chemical bath deposition (CBD) method. The effects of calcium doping content on their structural, morphological and optical properties were investigated by X-Ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and UV-vis spectroscopy measurements, respectively. According to X-Ray diffraction patterns all films were polycrystalline in nature, with a cubic crystal structure. It was observed from SEM analysis that calcium doping level affected the film morphology and surface roughness. Incorporation of Ca was confirmed from Energy dispersive X-Ray analysis results. Tauc method was used to estimate the optical band gap energies (E-g) of the pure and calcium doped films. UV-vis analysis showed that the transmittance of the samples varied between 15.3 and 20%. Also, it was observed that transmittance of deposited films increased with adding of calcium. Further, the optical energy band gap values were found to enhance (1.92-2.50 eV) with increasing the Ca content in PbS films. (C) 2017 Elsevier GmbH. All rights reserved.Öğe Fabrication and characterization of Sr-doped PbS thin films grown by CBD(Elsevier Sci Ltd, 2017) Yucel, Ersin; Yucel, YasinIn this work, undoped and Strontium-doped lead sulfide (PbS) thin films were deposited on glass substrates by chemical bath deposition (CBD) technique. The effect of Sr doping concentration on the structural, morphological and optical properties of the PbS thin films was studied. Changing in crystallite size, microstrain, dislocation density and band gap energy values of the PbS thin films as a function of Sr concentration were investigated by scanning electron microscopy (SEM), X-Ray diffraction (XRD) and UV-visible spectroscopy measurements. Energy dispersive X-Ray analysis (EDS) results indicated that nanostructured PbS films is doped with Sr without causing much lattice strain. According to XRD experiments crystallite size of the films is decreasing from 17.90 to 9.14 nm with increasing Sr-doping. UV-visible analysis showed that the band gap value of PbS thin films increased from 1.73 ev to 2.19 eV by changing Sr doping concentration from 0% to 5%.Öğe Mathematical modelling based on deposition parameters for optical band gap estimation of Sb2S3 thin films(Elsevier, 2024) Yucel, Ersin; Yucel, YasinA mathematical prediction model was developed to predict the band gap of Sb2S3 films based on the synthesis parameters. For the optimization of process parameters, a chemometric optimization approach was used instead of the traditional method. The band gaps of chalcogenide films were measured between 1.68 eV and 1.98 eV. The developed model was able to predict the band gap of the optimized Sb2S3 sample, measured as 1.71 eV, as 1.77 eV. The mathematical model achieved the band gap prediction of both the optimized Sb2S3 film and the test sample with a relative error of 3.51% and 2.23%, respectively. The data revealed that the developed model could reliably predict the band gap of Sb2S3 nanoparticles with a relative error of less than 5%. These findings may provide a significant advantage in nanoscale applications in terms of better understanding the predictability of the band gap of Sb2S3 films prior to synthesis.Öğe Modeling the Effect of Temperature and Potential on the In Vitro Corrosion Performance of Biomedical Hydroxyapatite Coatings(Springer, 2016) Coskun, M. Ibrahim; Karahan, Ismail H.; Yucel, Yasin; Golden, Teresa D.CoCrMo biomedical alloys were coated with a hydroxyapatite layer to improve biocompatibility and in vitro corrosion performance. A fast electrodeposition process was completed in 5 minutes for the hydroxyapatite coating. Effect of the solution temperature and applied potential on the in vitro corrosion performance of the hydroxyapatite coatings was modeled by response surface methodology (RSM) coupled with central composite design (CCD). A 5-level-2-factor experimental plan designed by CCD was used; the experimental plan contained 13 coating experiments with a temperature range from 283 K to 347 K (10 A degrees C to 74 A degrees C) and potential range from -1.2 to -1.9 V. Corrosion potential (E (corr)) of the coatings in a simulated body fluid solution was chosen as response for the model. Predicted and experimental values fitted well with an R (2) value of 0.9481. Response surface plots of the impedance and polarization resistance (R (P)) were investigated. Optimized parameters for electrodeposition of hydroxyapatite were determined by RSM as solution temperature of 305.48 K (32.33 A degrees C) and potential of -1.55 V. Hydroxyapatite coatings fabricated at optimized parameters showed excellent crystal formation and high in vitro corrosion resistance.Öğe Optimization and modelling of preparation conditions of CuS thin films deposited by successive ionic layer adsorption and reaction (SILAR) method using response surface methodology(Springer, 2015) Yucel, Yasin; Yucel, Ersin; Gokhan, DidemIn this study, CuS thin films were deposited on glass substrates by SILAR method with different pH, dipping time and dipping cycles. For the first time, response surface methodology was used for optimization CuS thin film coating parameters. 5-level-3-factor central composite design was employed to evaluate the effects of the deposition parameters (pH, dipping time and dipping cycles) on the optical band gap of the films. The significant level of the main effects and the interactions were investigated by analysis of variance. The morphological, structural and optical properties of the films were investigated by SEM, XRD and UV-Vis. The optimum pH, dipping time and dipping cycles were found to be 11.5, 31 s and 15 cycles, respectively. Under these conditions, the experimental band gap of CuS was observed as 2.18 eV which was well in close agreement with predicted value (2.11 eV) by the model. Quality of the film was improved after chemometrics optimization.Öğe Optimization and Modelling of Process Conditions Using Response Surface Methodology (RSM) for Enzymatic Saccharification of Spent Tea Waste (STW)(Springer, 2015) Yucel, Yasin; Goycincik, SezerSpent tea waste (STW) is an important lignocellulosic waste as a cost-effective feedstock for ethanol production. The enzymatic hydrolysis of acid pretreated STW was investigated in this study. The effects of process parameters, including acid pretreatment time 26.4-93.6 min, beta-glucosidase loading from 20 to 80 IU/g and cellulase loading from 11 to 45 IU/g on reducing sugar yield, were optimized by using central composite design of response surface methodology. The analysis of variance of data was examined by using response surface quadratic model. The valid model was used for optimization of the reducing sugar concentration during enzymatic hydrolysis. The optimum conditions for enzymatic saccharification were found to be acid pretreatment time of 27 min, beta-glucosidase loading of 49 IU/g and cellulase loading of 12 IU/g. Maximum concentration of the reducing sugar under the optimum conditions was determined as 29.0 g reducing sugar/L.Öğe Optimization of biocatalytic biodiesel production from pomace oil using response surface methodology(Elsevier, 2012) Yucel, YasinMicrobial lipase from T. lanuginosus was immobilized onto polyglutaraldehyde-activated olive pomace powder. The support was used to produce biodiesel with pomace oil and methanol. Response Surface Methodology (RSM) in combination with Central Composite Design (CCD) was used to optimize the biodiesel production parameters. Reaction temperature, molar ratio of methanol to oil, biocatalyst content and reaction time were chosen as the variables and the response selected was the yield of pomace oil methyl ester in present work. A quadratic polynomial equation was obtained for pomace oil methyl ester yield by multiple regression analysis. The optimal conditions for the transesterification have been found to be: reaction temperature of 40 degrees C, alcohol/oil molar ratio of 5.3:1, biocatalyst content of 5.8% w/w and reaction time of 24 h. The predicted pomace oil methyl ester yield was 92.87% under the optimal conditions. Verification experiment (91.81%) confirmed the validity of the predicted model. Biodiesel yield reached 93.73% by adding water (1% w/w) in reaction medium under the optimal conditions. Immobilized lipase was used to determine operational stability and it indicated that immobilized lipase was stable retaining more than 80% residual activity after being used repeatedly for 10 consecutive batches of pomace oil transesterification. (c) 2012 Elsevier B.V. All rights reserved.Öğe Optimization of deposition conditions of CdS thin films using response surface methodology(Elsevier Science Sa, 2014) Yucel, Ersin; Guler, Nuray; Yucel, YasinCadmium sulfide (CdS) thin films were prepared on glass substrates by chemical bath deposition (CBD) technique under different pH, stirring speed and deposition time. Response Surface Methodology (RSM) and Central Composite Design (CCD) were used to optimization of deposition parameters of the CdS thin films. RSM and CCD were also used to understand the significance and interaction of the factors affecting the film quality. Variables were determined as pH, stirring speed and deposition time. The band gap was chosen as response in the study. Influences of the variables on the band gap and the film quality were investigated. 5-level-3-factor central composite design was employed to evaluate the effects of the deposition conditions parameters such as pH (10.2-11.8), stirring speed (132-468 rpm) and deposition time (33-67 min) on the band gap of the films. The samples were characterized using X-ray diffraction (XRD), scanning electron microscope (SEM) and ultraviolet-visible spectroscopy (UV-vis) measurements. The optimal conditions for the deposition parameters of the CdS thin films have been found to be: pH 11, 361 of stirring speed and 55 min of deposition time. Under the optimal conditions theoretical (predicted) band gap of CdS (2.66 eV) was calculated using optimal coded values from the model and the theoretical value is good agreement with the value (2.72 eV) obtained by verification experiment. (C) 2013 Elsevier B. V. All rights reserved.Öğe Optimization of electrochemical step deposition for bioceramic hydroxyapatite coatings on CoCrMo implants(Elsevier Science Sa, 2016) Coskun, M. Ibrahim; Karahan, Ismail H.; Yucel, Yasin; Golden, Teresa D.CoCrMo metallic implants were coated with a bioceramic hydroxyapatite layer using a modified step electro-deposition at room temperature. Response Surface Methodology (RSM) and Central Composite Design (CCD) were used to model and optimize the step deposition parameters, such as initial potential, scan rate and peak potential. Interactions between step deposition parameters and in vitro corrosion performance of the coatings were modeled by response surface plots. Predicted and experimental values were fitted with high accuracy. The effects of the step deposition parameters were evaluated within the limits of lowest applied potential (-0.03 to -1.17 V), scan rate (3.43-116.57 mV/s) and highest applied deposition potential (-1.08 to -1.92 V). A 5-level-3-factor experiment plan was used to optimize step deposition parameters. Optimum conditions for the modified step deposition parameters were determined as initial potential of -0.76 V, peak potential of -1.67 V and scan rate of 59.33 mV/s. (C) 2015 Elsevier B.V. All rights reserved.Öğe Optimization of ethanol production from spent tea waste by Saccharomyces cerevisiae using statistical experimental designs(Springer Heidelberg, 2015) Yucel, Yasin; Goycincik, SezerThe aim of this study was to investigate the prospect for the use of spent tea waste (STW), an important municipal waste, as a potential substrate to generate hydroly-sates for fuel ethanol production. Acid pretreated STW was used as substrate for ethanol production. The critical variables that affected ethanol fermentation from STW were identified by Plackett-Burman designs and further optimized by using a five-level-three-factor central composite design of response surface methodology. The optimum conditions for ethanol fermentation were determined to be NH4Cl concentration of 2.7 g/L, yeast concentration of 11.7 g/L, and temperature of 42.8 degrees C. Maximum concentration of reducing sugar and ethanol under the optimum conditions were 28.90 g reducing sugar/L and 12.72 g EtOH/L, respectively. Predicted ethanol concentration was obtained using quadratic polynomial equation. The predicted ethanol concentration was 13.38 g EtOH/L in the optimal conditions. Validity of the predicted model was confirmed using verification experiment (12.72 g EtOH/L).Öğe Optimization of fabrication conditions of MgB2/Fe superconducting tapes using response surface methodology(Springer, 2012) Yucel, Ersin; Yucel, Yasin; Belenli, IbrahimWe have optimized fabrication conditions of MgB2/Fe superconducting monofilament tapes fabricated using ex-situ powder-in-tube method without any intermediate annealing. Influences of three effective parameters (annealing temperature, annealing time and argon (Ar) gas atmosphere pressure during the heat treatments) on the transport critical current densities (J(c)) were investigated. The samples were characterized using X-ray diffraction, scanning electron microscope, energy dispersive X-ray spectrometer, optical microscope, critical transition temperature and J(c) measurements. Response surface methodology was used to optimize the conditions for the maximum J(c) of the samples and to understand the significance and interaction of the factors affecting J(c). 3-level-3-factor central composite design was employed to evaluate the effects of the fabrication conditions parameters such as annealing temperatures (850-950 A degrees C), annealing times (30-120 min.) and Ar pressures (1-5 bars) on J(c) of the samples. Based on the analysis of ridge max, the optimum fabrication conditions were as follows: annealing temperature 948 A degrees C, annealing time 58 min. and Ar pressure 3 bars.
