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Öğe 157-nm Laser Micromachining of N-BK7 Glass and Replication for Microcontact Printing(Springer-Verlag, 2003) Dyer, P. E.; Maswadi, S. M.; Walton, C. D.; Ersöz, Mustafa; Fletcher, P. D. I. ; Paunov, V. N.We report etch-rate and probe-beam-deflection studies of N-BK7 glass ablated using a 157-nm F-2 laser. It is found that controllable material removal at the nanometre level is possible above an ablation threshold of 250 mJ cm(-2). Contact mask printing shows well-defined features can be micromachined in this glass with sub-micron resolution capability. Micro-features produced in this way have been replicated by polydimethylsiloxane (PDMS) moulding and the stamps used to print arrays of fluorescent molecules with sub-micron fidelity.Öğe Adsorption Characteristics of Heavy Metal İons Onto a Low Cost Biopolymeric Sorbent From Aqueous Solutions(Elsevier, 2006) Ünlü, Nuri; Ersöz, MustafaIn this study, the adsorption conditions of Cu(II), Pb(II) and Cd(II) metal ions onto sporopollenin have been studied. The different variables effecting the sorption capacity such as pH of the solution, adsorption time, initial metal ion concentration and temperature have been investigated. Adsorption isotherms correlated well with the Freundlich type adsorption isotherm and adsorption capacities were found to be 0.0195, 0.0411 and 0.0146 mmol g(-1) for Cu(II), Pb(II) and Cd(II) metal ions, respectively. Experimental data were also evaluated to find out kinetic characteristics of the adsorption process. Adsorption processes for three target heavy metal ions were found to follow pseudo-second order type adsorption kinetics. Intraparticle diffusion was found to take part in adsorption processes but it could not be accepted as the primary rate-determining step. The mean free energies of adsorption (E) were found to be between 8 and 16 kJ mol(-1) for the metal ions studied and therefore adsorption mechanism for the adsorbent was explained as an ion-exchange process. But it was observed that chelating effect is also playing an important role in the adsorption of metal ions onto sporopollenin. Thermodynamic parameters, Delta H degrees, Delta S degrees and Delta G degrees were also calculated from graphical interpretation of the experimental data. Standard heats of adsorption (Delta H degrees) were found to be endothermic and AS' values were calculated to be positive for the adsorption of Cu(II), Pb(II) and Cd(II) ions onto the adsorbent. Negative Delta G degrees values indicated that adsorption process for these three metal ions onto sporopollenin is spontaneous.Öğe Adsorption of Copper ( II ) , Cobalt ( II ) , and Iron ( III) Ions From Aqueous Solutions on Poly ( Ethyleneterephthalate ) Fibers(JOHN WILEY & SONS INC, 1998) Yigitoğlu, Mustafa; Ersöz, Mustafa; Coşkun, Ramazan; Şanlı, Oya; Ünal, Halil İbrahimThe adsorption behavior of poly ( ethylene terephthalate ) ( PET ) fibers to-wards copper ( II ) , cobalt ( II ) , and iron ( III ) ions in aqueous solutions was studied by abatch equilibriation technique. Influence of treatment time, temperature, pH of thesolution, and metal ion concentration on the adsorption were investigated. Adsorptionvalues for metal ion intake followed the following order: Co ( II )úCu(II)úFe( III ) .One hour of adsorption time was found sufficient to reach adsorption equilibrium forall the ions. The rate of adsorption was found to decrease with the increase in thetemperature. Langmuir adsorption isoterm curves were found to be significant for allthe ions studied. The heat of adsorption values were calculated as05,02.8, and03.6kcal /mol for Cu ( II ) , Co ( II ) , and Fe( III ) ions, respectively.Öğe Adsorption of Cu(II) From Aqueous Solution by Using Modified Fe3O4 Magnetic Nanoparticles(Elsevier, 2010) Özmen, Mustafa; Can, Keziban; Arslan, Gülsin; Tor, Ali; Çengeloğlu, Yunus; Ersöz, MustafaIn this study, surface modification of Fe3O4 nanoparticles (Fe3O4-NPs) was carried out with 3-aminopropyltriethoxysilane (APTES) and glutaraldehyde (GA). The obtained modified-NPs (GA-APTES-NPs) were evaluated for Cu(II) removal from water by adsorption. First, Fe3O4-NPs were synthesized by co-precipitation of Fe2+ and Fe3+ with Fe2+/Fe3+ in a ratio of 1.75 in an ammonia solution, then surface of Fe3O4-NPs was modified with APTES and GA. The morphology and properties of the NPs were examined by Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FT-IR), Thermal Gravimetric Analysis (TGA) and magnetization measurement. The batch experiments showed that modified-NPs can be effectively used to remove Cu(II) from water. Adsorption equilibrium was achieved in 15 min. The adsorption of Cu(II) by GA-APTES-NPs strongly depends on the pH of the solution. Maximum removal of Cu(II) was obtained at pH between 4.0 and 5.3. The isotherm analysis indicated that the sorption data can be represented by both Langmuir and Freundlich isotherm models. The regeneration studies also showed that GA-APTES-NPs could be re-used for the adsorption of Cu(II) from aqueous solutions over three cycles without change in the sorption capacity and magnetization properties.Öğe Adsorption of Cu(II) onto silica gel-immobilized Schiff base derivative(ELSEVIER, 2009) Gübbük, I. Hilal; Gup, Ramazan; Kara, Huseyin; Ersöz, Mustafa4-chloroisonitroacetophenone 4-aminobenzylhydrazone (CAAH) chemically anchored on a silica gel surface, has been used for Cu(II) sorption from aqueous solution. The surface modification processes was performed after silanization of silica, then analyzed by elemental analysis, infrared spectroscopy, and thermogravimetry. The sorption behavior of copper(II) was evaluated by the use of batch and column methods. The influences of the concentration, temperature and pH for sorption on the immobilized silica gel with Schiff base were investigated. The obtained dynamic data were fitted to Freundlich, Langmuir and Dubinin-Raduskevich (D-R) isotherms. The mean sorption energy (E) of copper sorption onto silica gel was calculated from D-R isotherm indicating a chemical ion-exchange. The thermodynamic parameters such as Gibbs free energy change, enthalpy change and entropy change were calculated from the adsorption isotherms which were used to explain the mechanism of the adsorption. (C) 2009 Published by Elsevier B.V.Öğe Amperometric Glucose Biosensor Based on Glucose Oxidase, 1,10-Phenanthroline-5,6-dione and Carbon Nanotubes(ELECTROCHEMICAL SOC INC, 2014) Zor, Erhan; Öztekin, Yasemin; Ramanaviciene, Almira; Anusevicius, Zilvinas; Bingöl, Haluk; Barkauskas, Jurgis; Ersöz, MustafaA biosensor for glucose determination was fabricated by the immobilization of glucose oxidase (GOx) on carbon nanotubes (CNTs) and/or 1,10-phenanthroline-5,6-dione (PD) modified graphite rod electrodes (GOx/PD/CNTs/GR) and its amperometric response toward glucose was investigated under aerobic and anaerobic conditions. The sensitivity of the GOx/PD/CNTs/GR electrode was found to be higher compared to that of a PD-modified GR electrode without CNTs (GOx/PD/GR), implying that CNTs play an important role in the facilitation of electron transfer between the redox active site of GOx and the electrode surface. The GOx/PD/CNTs/GR biosensor exhibited a linear dependency on substrate concentration in a range from 0.0 until 50.0 mM of glucose with oxygen present and from 0.0 until 62.5 mM of glucose in the absence of oxygen. With oxygen present, the limit of detection (LOD) values were determined to be 5.4 and 8.0 mM, and the limit of quantitation values (LOQ) were calculated as 16.2 and 24 mM for GOx/PD/GR and GOx/PD/CNTs/GR, respectively. In the absence of oxygen, the LOD values were calculated as 4.2 and 10.7 mM, and the LOQ values were calculated as 12.6 and 32.1 mM for GOx/PD/GR and GOx/PD/CNTs/GR, respectively. When examining the interference effect of uric acid for GOx/PD/GR and GOx/PD/CNTs/GR electrodes, no significant changes in the amperometric response of the modified electrodes were observed up to 100.0 mM of uric acid. (C) 2014 The Electrochemical Society. All rights reserved.Öğe Arsenic(V) removal from underground water by magnetic nanoparticles synthesized from waste red mud(ELSEVIER SCIENCE BV, 2012) Akın, İlker; Arslan, Gülsin; Tor, Ali; Ersöz, Mustafa; Cengeloğlu, YunusIn this study waste red mud (bauxite residue) sample obtained from Seydisehir (Konya, Turkey) was evaluated for the synthesis of Fe3O4 nanoparticles (NPs) in ammonia solution that can be used to remove As(V) from both synthetic and natural underground water samples. The synthesized Fe3O4-NPs were characterized by using TEM, VSM, XRD, SAXS,TGA and FT-IR spectroscopy. The Fe3O4-NPs assumed a near-sphere shape with an average size of 9 nm. The results showed that synthesized Fe3O4-NP5 from waste red mud have satisfactory magnetic properties and As(V) sorption capacity, especially at low equilibrium arsenate concentrations. (c) 2012 Elsevier B.V. All rights reserved,Öğe Assembly of Non-Aqueous Colloidal Dispersions under External Electric Field(CRC PRESS-TAYLOR & FRANCIS GROUP, 2014) Ünal, Halil İbrahim; Erol, Özlem; Ersöz, Mustafa[Abstract not Available]Öğe Assessment of pharyngeal airway volume in adolescent patients affected by bilateral cleft lip and palate using cone beam computed tomography(E H ANGLE EDUCATION RESEARCH FOUNDATION, INC, 2014) Çelikoğlu, Mevlüt; Uçar, Faruk I.; Şekerci, Ahmet E.; Büyük, Süleyman K.; Ersöz, Mustafa; Şişman, YıldırayObjective: To test the null hypothesis that there were no significant differences for pharyngeal airway volumes between the adolescent patients affected by bilateral cleft lip and palate (BCLP) and well-matched controls using cone beam computed tomography. Materials and Methods: The study sample consisted of 16 patients (11 female and 5 male; mean [SD] age 14.1 [2.1] years) affected by BCLP and 16 patients (10 female and 6 male; mean [SD] age 13.4 [2.0] years) as age- and sex-matched control group. Craniofacial measurements and pharyngeal airway dimension, area, and volume measurements of patients in both groups were calculated and statistically examined using Student's t-test and multiple linear regression analyses. Results: Statistically significant differences were found between the BCLP and control groups for SNB (P <.05), SN-GoGn (P <.05), Co-A (P <.05), PAS (P <.01), minAx (P <.01), and oropharyngeal airway volume (P <.05). The most predictive variables for oropharyngeal airway volume were found as PAS (r =.655 and P =.000) and minAx (r =.787 and P =.000). Conclusions: The null hypothesis was rejected. Oropharyngeal (P <.05) and total (P>.05) airway volumes were found to be less in the BCLP group, and thus the treatment choice in these patients should have positive effects on the pharyngeal airway.Öğe Binding Affinity of Serum Proteins to Epoxy Modified Magnetite Nanoparticles(2012) Maltaş, Esra; Özmen, Mustafa; Yıldız, Salih; Ersöz, MustafaSuperparamagnetic iron oxide nanoparticles (SPIONs) were synthesized by co-precipitating Fe2+ and Fe3+ in an ammonia solution. SPIONs modified with [3-(2,3-epoxypropoxy)propyl] trimethoxy silane, which resulted in the presence of a high population of epoxy groups on the particles surface. The surface functional SPIONs can be bound with active bio-substance, and have a wide application prospect in the fields of biology and medicine. The binding percentage of proteins was studied with epoxy modified SPIONs. Several serum proteins including albumin, ?-globulin, hemoglobin, cytochrome c and myoglobin were studied for immobilization. Epoxy terminated SPIONs were shown the highest binding ability for immobilization of cytochrome c and hemoglobin with 1 and 0.86 mg total protein at a particle concentration of 20 mg/mL among proteins, respectively. This binding ability was also shown by using sodium dodecylsulfate polyacrylamide gel electrophoresis technique (SDS-PAGE). Protein attachments were also examined by Scanning Electron Microscopy (SEM). © 2012 American Scientific Publishers. All rights reserved.Öğe Biocompatible multi-walled carbon nanotube-CdTe quantum dot-polymer hybrids for medical applications(ELSEVIER SCIENCE BV, 2015) Başlak, Canan; Kars, Meltem Demirel; Karaman, Mustafa; Kuş, Mahmut; Çengeloğlu, Yunus; Ersöz, MustafaHerein we report the synthesis of polymer coated quantum dots (QDs)-carbon nanotube composite material with high biocompatibility and low cellular toxicity. The synthesized multi-walled carbon nanotube (MWCNT)-QD-(-poly(glycidyl methacrylate)) (pGMA) hybrids were characterized using X-ray photoelectron spectroscopy, laser scanning confocal microscopy, transmission electron microscopy and scanning electron microscopy. The results showed that quantum dots were well-distributed on nanotube surfaces in high density. The toxicological assessments of QDs and MWCNT-QD-polymer hybrids in human mammary carcinoma cells and their fluorescence imaging in living cell system were carried out. MWCNT-QD-polymer hybrids possess intense red fluorescence signal under confocal microscopy and good fluorescence stability over 6-h exposure in living cell system. The toxicity comparison of QDs and MWCNT-QD-polymer hybrids has shown that the existence of PGMA thin coating on MWCNT-QD hybrid surface decreased the cellular toxicity and increased biocompatibility. (C) 2014 Elsevier B.V. All rights reserved.Öğe Biofuel Cell Based on Anode and Cathode Modified by Glucose Oxidase(WILEY-V C H VERLAG GMBH, 2013) Krikstolaityte, Vida; Öztekin, Yasemin; Kuliesius, Jurgis; Ramanaviciene, Almira; Yazıcıgil, Zafer; Ersöz, Mustafa; Okumuş, AytuğA single compartment biofuel cell (BFC) based on an anode and a cathode powered by the same fuel glucose is reported. Glucose oxidase (GOx) from Aspergillus niger was applied as a glucose consuming biocatalyst for both anode and cathode of the BFC. The 5-amino-1,10-phenanthroline modified graphite rod electrode (GRE) with cross-linked GOx was used as the bioanode, and the GRE with co-immobilised horseradish peroxidase and GOx was exploited as the biocathode of the BFC. The open-circuit voltage of the designed BFC exceeded 450mV and a maximal power density of 3.5 mu W/cm(2) was registered at a cell voltage of 300mV.Öğe Calix[4]arene derivative bearing imidazole groups as carrier for the transport of palladium by using bulk liquid membrane(ELSEVIER SCIENCE BV, 2012) Akın, İlker; Erdemir, Serkan; Yılmaz, Mustafa; Ersöz, MustafaThe carrier activity of calix[4]arene containing imidazole groups towards the facilitated transport of palladium(II) through dichloromethane bulk liquid membrane has been studied. The optimum transport conditions were established by the studies on the effect of pH, feed concentration, carrier concentration, receiver phase concentration and transport time. A solution of 1 M hydrochloric acid (HCl) served as receiving phase for maximum transport of the metal ion. Maximum transport efficiency was observed for Pd(II) ion when it was present in the concentration of 10(-3) M and the transport efficiency after 24 h was found as 95%. (C) 2012 Elsevier B.V. All rights reserved.Öğe A Calix[4]arene-Containing Polysiloxane Resin for Removal of Heavy Metals and Dichromate Anion(Taylor & Francis Inc, 2006) Tabakçı, Mustafa; Ersöz, Mustafa; Yılmaz, MustafaA new calix[4]arene-based polysiloxane resin (CBPSR) was prepared from 5,11,17,23-tert-butyl-25,27-bis(cyanomethoxy)-26-(chloroformyl)-28-hydroxy-calix[4]arene via nucleophilic substitution reaction with 3-aminopropyltriethoxysilane and followed by copolymerization with octyltriethoxysilane. Batchwise extraction studies have revealed a high adsorption ability of the calix[4]arene-nitrile derivatives loaded resin toward heavy metals (Cu(2+) , Co(2+) , Cd(2+) , Ni(2+) , Hg(2+) and Pb(2+) ) and dichromate anion (Cr(2)O(7)(2-) ). Liquid-liquid extraction studies show that the monomeric analogs (2, 3 and 4) do not exhibit a good affinity toward these ions.Öğe Calixarene assembly with enhanced photocurrents using P(SNS-NH2)/CdS nanoparticle structure modified Au electrode systems(ROYAL SOC CHEMISTRY, 2015) Sayın, Serkan; Azak, Hacer; Yıldız, Hüseyin Bekir; Çamurlu, Pınar; Akkuş, Gülderen Uysal; Toppare, Levent; Ersöz, MustafaTwo novel calix[n] arene-adorned gold electrodes producing high photocurrent intensities were successfully constructed by embedding gold electrode surfaces with both P(4-(2,5-di(thiophen-2-yl)-1H- pyrrol-1-yl)benzenamine) conducting polymer and 4-mercaptoboronic acid-functionalized semiconductor CdS nanoparticles to facilitate the binding of calix[n]arene sulfonic acids with nanoparticles. This structure enabled an electron transfer cascade that both induced effective charge separation and efficiently generated photocurrent. The prepared electrodes were used to generate photocurrent by relying on the host-guest interactions of guests Br-3(-) and I-3(-), which if positioned well in the system was able to fill electron-hole pairs of CdS nanoparticles. As a result, host calixarene derivatives crucially held Br-3(-) and I-3(-) ions at a substantial distance from CdS nanoparticles. Furthermore, the effects of various calixarenes on the photocurrent obtained indicate that the generation of photocurrent intensities by the system depends on the cavity sizes of calixarene derivatives, which provide an essential center for Br-3(-) and I-3(-) ions.Öğe Catalytic Hydrogen Evolution by Tungsten Disulfide at Liquid-Liquid Interfaces(WILEY-V C H VERLAG GMBH, 2014) Aslan, Emre; Patır, İmren Hatay; Ersöz, MustafaWS2, which is composed of cheap and earth-abundant elements, catalyzes the hydrogen-evolution reaction efficiently using the organic electron-donor decamethylferrocene. This catalytic activity has been investigated at liquid-liquid interfaces (water-1,2-dichloroethane) by voltammetry and biphasic reactions observed by UV/Vis spectroscopy and GC.Öğe Colloidal CuZnSnSe4-xSx nanocrystals for hybrid solar cells(ELSEVIER, 2015) Kuş, Mahmut; Özel, Faruk; Büyükçelebi, Sümeyra; Aljabour, Abdalaziz; Erdoğan, Ayşenur; Ersöz, Mustafa; Sarıçiftçi, Niyazi SerdarWe report the synthesis of different colloidal CZTSe(4-x)S(x) nanocrystals and their performance in [6,6]-phenyl C61 butyric acid methyl ester (PCBM) based organic/inorganic hybrid bulk heterojunction solar cells. Synthesis of colloidal CuZnSnSe4-xSx were performed and characterized by XRD, TEM, SEM, UV-Visible absorption techniques. Electrochemical and photovoltaic properties were investigated. The best device concept, ITO/PEDOT:PSS/CZTS:PCBM blend (1:10)/Al, showed 280 mu A/cm(2) short circuit current, I-sc with 300 mV open circuit voltage V-oc, and fill factor FF of 0.38. (C) 2014 Elsevier B.V. All rights reserved.Öğe A comparative study and evaluation of magnetic and nonmagnetic hydrogels towards mitigation of di butyl and di ethyl hexyl phthalate from aqueous solutions(ELSEVIER SCIENCE BV, 2016) Qureshi, Umair A.; Gübbük, İlkay Hilal; Ersöz, Mustafa; Solangi, Amber R.; Taqvi, Syed I. H.; Memon, Saima Q.This study was focused on preparation of a new hydrogel adsorbent material based on chitosan, polyvinyl alcohol and magnetic particles. These materials were prepared by varying their ratio and were compared with each other in terms of swelling and adsorption performance for two model endocrine disrupting compounds i.e. dibutyl phthalate (DBP) and diethyl hexyl phthalate (DEHP). Two gels (gel 0 and CS 0.5) were selected for differentiating their adsorption efficiencies as a function of pH, time, concentrations, temperature and interference in batch mode against toxic phthalates. Among the two gels, CS 0.5 was found to be promising than gel 0 and showed better performance toward DBP and DEHP removal. The adsorption mechanism was found to be dominated by hydrogen bonding on gel 0. Additionally, complexation interaction and hydrophobic interactions on CS 0.5 were playing crucial role. The gels can be applied effectively for the elimination of DBP and DEHP pollution from waste water. (C) 2015 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.Öğe A comparative study on fabrication of Cu2ZnSnS4 (CZTS) nanofibers using acetate and chloride metal precursors(SCIENTIFIC TECHNICAL RESEARCH COUNCIL TURKEY-TUBITAK, 2015) Büyükbekar, Burak Zafer; Özel, Faruk; Şakalak, Hüseyin; Çavuşoğlu, Halit; Ersöz, Mustafa; Kuş, Mahmut; Yavuz, Mustafa SelmanThis study reports, for the first time, the fabrication of electrospun Cu2ZnSnS4 (CZTS) nanofibers using metal acetate precursors. Viscous poly(vinyl pyrrolidone) (PVP) solution containing acetate or chloride salts of copper, zinc, and tin was electrospun onto a conductive substrate. The PVP nanofibers that have a mixture of metal salts were annealed at elevated temperatures. After calcination, these nanofibers were treated with the sulfur source and then annealed again in order to generate CZTS nanofibers. The CZTS nanofibers generated from acetate and chloride salts were characterized and compared. Belt-like and wire-like nanofibers were obtained when using metal acetate and chloride precursors, respectively.Öğe A comparative study on fluorescence quenching of CdTe nanocrystals with a serial of polycyclic aromatic hydrocarbons(ELSEVIER SCIENCE BV, 2014) Başlak, Canan; Kuş, Mahmut; Çengeloğlu, Yunus; Ersöz, MustafaWe report sensing different polycyclic aromatic hydrocarbons (PAHs) with colloidal CdTe nanocrystals. The effect of molecular structure on quenching rate for 2-hyroxy-1-naphthaldehyde (2H-1N), 9,10-phenanthraquinone (PQ), 9-anthracenecarboxaldehyde (9-AC) and quinoline (Q) is presented. The quenching rate constants are observed to be strongly dependent on the molecular structure. PQ consisting of two carbonyl groups, shows the highest rate constant while Q shows the worst one. Both static and dynamic quenching are simultaneously observed for PQ and 2H-1N. Therefore extended Stern-Volmer equations are used to calculate rate constants. Results showed that dynamic quenching is a dominant process. The rate constants for PQ 2H-1N, 9-AC and Q are calculated to be 64.84, 10.73, 10.66 and 1.85 respectively. (C) 2014 Elsevier B.V. All rights reserved.
