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    The green synthesis of oligo(azomethine)s based on p-anisidine and o-anisidine: reaction conditions, electrochemical and thermal properties
    (Taylor & Francis Inc, 2022) Kaya, Ismet; Koca, Semra; Yagmur, Hatice Karaer
    Schiff bases and their conjugated oligo(azomethine)s have been synthesized via condensation and oxidative polycondensation of o-anisidine (OA) with 2-hydroxy-1-naphthaldehyde (2-HNA) and p-anisidine (PA) with 4-hydroxy benzaldehyde (4-HBA), respectively. The oxidative polycondensation reaction conditions of 1-[(2-methoxyphenylimino)methyl]naphthalen-2-ol (1,2-MPIMN) and 4-[(4-methoxyphenylimino)methyl]phenol (4,4-MPIMP) were studied by oxidants such as air and aqueous solutions of H2O2 and NaOCl in different concentrations in an aqueous alkaline medium between 50 degrees C and 90 degrees C at different reaction times. The structures of polymers were confirmed by FT-IR, UV-Vis and H-1-C-13-NMR measurements. The molecular weights and surface morphologies of oligomers were determined by size exclusion chromatography (SEC) and scanning electron microscopy (SEM), respectively. Electrochemical and thermal features of compounds were studied using UV-Vis spectroscopies, cycling voltammetry (CV), and TG-DTA. The mass losses values of the 1,2-MPIMN, oligo(1,2-MPIMN), 4,4-MPIMP, and oligo(4,4-MPIMP) were calculated from the thermogravimetric curves as 98.00%, 53.52%, 69.00%, and 58.70%, respectively, at 1000 degrees C. The HOMO, LUMO levels, electrochemical (E-g(')), and optical band gap energies (E-g) values of the compounds were calculated from CV and UV-Vis data. The E-g(') values of 1,2-MPIMN, oligo(1,2-MPIMN), 4,4-MPIMP, and oligo(4,4-MPIMP) were found to be 2.64, 1.54, 2.31, and 2.16 eV, respectively. The electrical properties of monomers and oligomers were determined at room temperature.
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    An Investigation of the Perceptions of School Administrators Towards the Roles and Duties of School Counselors
    (Ani Yayincilik, 2015) Karatas, Kasim; Kaya, Ismet
    Problem Statement: School administrators are the first responsible body for the implementation of the counseling and guidance program. For sharing this responsibility, school administrators should be in cooperation with school counselors. Administrators' perceptions on school counseling and guidance services show that school administrators have positive attitudes toward counseling services and they cooperate with the counselors at school. School administrators describe counseling services as necessary and successful activities. However, other studies show that school administrators are of the opinion that counselors should perform tasks that are not in their job descriptions. In short, school administrators' perceptions on school counseling and guidance services and the tasks and missions of school counselors vary greatly and there is no consensus among the administrators. It is important to investigate the perceptions and views of school administrators towards counselors. Therefore, the present study aimed to contribute to the current literature via offering suggestions to increase the productivity and effectiveness of school counselors. Purpose of the Study: The aim of this study is to investigate the perceptions of school administrators who are important shareholders in carrying out school counseling and guidance services. The sub-aims of the study are to investigate the status of school counselors, and the school administrators' expectations of school counselors, both in terms of personal and professional qualifications and in terms of the status and duties of the counselors. Method: This qualitative study investigates the perceptions of school administrators towards school counselors in terms of their roles and duties. The current research utilizes a phenomenological design. The participants of the study were 13 school administrators who were working in primary and secondary schools in downtown Diyarbakir. A semi-structured interview, developed by the researchers, was used to collect the data. Gathered data were first analyzed in terms of descriptive analyses and then digitized. Findings: Research findings show the administrators' positive perceptions of counselors being necessary and important in educational and instructional activities for every shareholder of education. School administrators listed a set of personal and professional qualifications for school counselors. In addition, school administrators are of the opinion that school counselors have some privileges apart from other teachers in terms of their status and role at the school. It is found that school administrators are well aware of the necessity and importance of school counselors, who serve as field experts at schools. Conclusion and Recommendations: In this study it is found that school managers are very aware of and positive about the school counseling and guidance field and counselors' teaching duties and responsibilities. The quality and efficiency of school counseling services should be increased, and the counselors' job description should be clarified by the Ministry of Turkish National Education to prevent confusion. School administrators and other shareholders should support the creation of a common professional identity for school counselors.
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    Synthesis and characterization of poly(3,5-diaminobenzoic acid) via enzymatic and oxidative polymerization and application in methylene blue adsorption
    (Elsevier, 2020) Kaya, Ismet; Yagmur, Hatice Karaer
    In the present study, polymers of substitute aromatic diamine were synthesized by oxidative and enzymatic polymerization. Enzymatic polymerization and oxidative polymerization of 3,5-diamino benzoic acid (DIABA) monomer in the presence of HRP (horse radish peroxidase) and H2O2 (hydrogen peroxide) were synthesized PDIABA-E and PDIABBA-O polymers. The structures of DIABA and polymers were confirmed by FT-IR, UV-Vis and NMR measurements. The characterizations of polymers were performed by GPC, TG-DTA, DSC, SEM and fluorescence measurements. Moreover, electrochemical fea-tures of polymers were performed with cyclic voltammetry (CV) measurements. The optical (E-g) and electrochemical (E'(g)) band gap values of PDIABA-O and PDIABA-E were calculated to be as 1.90 and 2.30 eV and 2.38 and 2.52 eV, respectively. The results showed that optical gaps and electrochemical band of PDIABA-E and PDIABBA-O were lower than those of DIABA due to their polyconjugated struc-tures. Quantum yield was calculated as 13% for PDIABA-O. Furthermore, PDIABA-O was used as a sorbent for the removal of methylene blue (MB) from aqueous solution. (C) 2020 Elsevier B.V. All rights reserved.
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    Synthesis of poly(4-aminosalicylic acid) through enzymatic and oxidative polycondensation by H2O2 oxidant
    (Springer, 2022) Kaya, Ismet; Yagmur, HaticeKaraer
    Aromatic compounds containing hydroxyl and amine groups in their structure are converted into oligomers or polymers through oxidative polymerization in water or organic solvent media. Again, aromatic amine or aromatic hydroxyl compounds are converted into oligomers or polymers by horseradish peroxidase (HRP) enzyme at different pH values in water or organic solvent media. Since the enzymatic oligomerization or polymerization of such compounds is environmentally sensitive, they are referred to as green chemistry. Poly(4-aminosalicylic acid) was synthesized by both enzymatic (PASA-E) and oxidative polycondensation (PASA-O) reactions. The structure and characterization were determined by FTIR, UV-vis, NMR, TGA, fluorescence and SEM measurements.PASA-O from 4-aminosalicylic acid was obtained by chemical oxidative polycondensation in glacial acetic acid by H2O2 (35% aqueous solution) as an oxidant. Enzymatic oxidative polymerizationof 4-aminosalicylic acid was performed by HRP. It has important advantages such as mild reaction conditions, mainly in terms of temperature and toxicity.The optical bandgap (E-g) values of ASA, PASA-O and PASA-E polymers were calculated to be 3.72, 2.40, and 2.73 eV, respectively. The electrochemical properties of compounds were determined by CV. The electrochemical bandgap (E '(g)) values of PASA-O and PASA-E were determined as 2.16 and 2.68 eV, respectively. The residual amount of PASA-O was higher than that of ASA and PASA-E at 1000 degrees C.
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    Synthesis, characterization and electrochemical properties of poly (phenoxy-imine)s containing carbazole unit
    (Springer Heidelberg, 2017) Kaya, Ismet; Copur, Sebra; Karaer, Hatice
    Several new Schiff base polymers were synthesized via oxidative polymerization method in an aqueous alkaline medium in the presence of NaOCl as an oxidant and were confirmed by FT-IR, H-1-NMR, C-13-NMR and UV-Vis spectroscopic techniques. Furthermore, cyclic voltammetry measurements were carried out and the HOMO-LUMO energy levels and electrochemical band gaps (E-g') were calculated. Additionally, the optical band gaps (E-g) were determined using their UV-Vis spectra of the materials. The morphologic properties of the polymers were investigated by scanning electron microscopy. In addition, the number average molecular weight (M-n), weight average molecular weight (M-w) and polydispersity index values of the polymers were determined by gel permeation chromatography technique. Electrical conductivity measurements of the doped (with iodine) and undoped polymer related to doping time were carried out by four-point probe technique using a Keithley 2400 electrometer. Their thermal behaviors were determined by TG-DTA and DSC measurements. The synthesized compounds were soluble in common solvents such as DMF, THF and DMSO. Photoluminescence properties of the polymers were determined in different concentrations of DMF solvent.
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    Synthesis, characterization and using at the copper adsorption of chitosan/polyvinyl alcohol magnetic composite
    (Elsevier, 2017) Karaer, Hatice; Kaya, Ismet
    A chitosan/polyvinyl alcohol (CTN/PVA-Fe3O4) magnetic composite was prepared in one step and examined by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDX), transmission electron microscopy (TEM), dynamic light scattering (DLS), Brunauer-Emmett-Teller (BET), thermal gravimetric analysis/differential thermal analysis (TGA-DTA) and differential scanning calorimetry (DSC). Effects of several parameters, such as temperature, pH, and initial concentration on removal of Cu(II) from aqueous solution by the CTN/PVA magnetic composite were studied as a function of contact time. Equilibrium data obtained from sorption of Cu(II) solutions having initial concentrations of 25 to 400 mg L-1 by sorption of the CTN/PVA magnetic composite at different temperatures (25, 35 and 45 degrees C) were applied to Langmuir and Freundlich adsorption isotherms. Maximum adsorption capacity (Q(max))was found to be 143 mg g(-1) by using Langmuir isotherm model, by which thermodynamic parameters (Delta H degrees, Delta G degrees and Delta S degrees) were also calculated. Activation energy was calculated by using rate constants for this model and its value was found 26.52 kJ mol(-1). (C) 2017 Elsevier B.V. All rights reserved.
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    Synthesis, characterization of magnetic chitosan/active charcoal composite and using at the adsorption of methylene blue and reactive blue4
    (Elsevier Science Bv, 2016) Karaer, Hatice; Kaya, Ismet
    In this study, a chitosan/activated charcoal (or carbon) (CTN/AC-Fe3O4) composite was obtained in one step, characterized several techniques such as by Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, dynamic light scattering, Brunauer-EmmetTeller, thermogravimetric analysis/differential thermal analysis and differential scanning calorimetry techniques. The sorption the composite were investigated as kinetically and thermodynamically for removal of methylene blue (MB) and reactive blue4 (RB4) from aqueous solution. Effects of several parameters, such as initial temperature and initial concentration on removal of MB and RB4 from aqueous solution by the composite were investigated as a function of contact time. Maximum adsorption capacity (Qmax) was found to be 500 mg g(-1) at and 250 mg g(-1) at 318 K for MB, 298 K for RB4 respectively. Also, thermodynamic parameters such as Delta H-0, Delta G(0)and Delta S-0 were calculated by Langmuir adsorption isotherm model. Negative Gibbs free energy (Delta G(0)) implies that the adsorption is spontaneous and positive adsorption enthalpy (Delta H-0) demonstrates the process is endothermic for MB while negative adsorption enthalpy (Delta H-0) demonstrates the process is exothermic for RB4, respectively. (C) 2016 Elsevier Inc. All rights reserved.
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    Synthesis, characterization, and thermal decompositions of Schiff base polymers containing chitosan unit
    (Springer, 2015) Karaer, Hatice; Kaya, Ismet
    The most plentiful natural biopolymer chitin and chitosan have become center of attraction of all party because of an unusual combination of biological activities, mechanical and physical properties. The several chemical modifications such as oligomerization, alkylation, quternization, enzymatic modifications, and graft copolymerization along with many assorted modifications have been carried out. However, its applications have only been shown in acidic medium because of its poor solubility in neutral and basic pH. In view of rapidly growing interest in chitosan its chemical aspects and chemical modification studies are reviewed. Four different aldehyde types, namely 4-hydroxybenzaldehyde (4HBA), 2-hydroxybenzaldehyde (2HBA), vanillin (VAN), 3-thiophenecarboxaldehyde (3TPCA), and their poly(4-hydroxybenzaldehyde) (P4HBA), poly(2-hydroxybenzaldehyde) (P2HBA), and poly (vanillin) (PVAN) were treated with chitosan to obtain Schiff base polymers. Although some of the chitosan-based Schiff bases were present in the literature, contrary to the literature the aldehydes (4HBA, VAN, 2HBA) were polymerized via oxidative polycondensation, followed by their reaction with chitosan to provide the Schiff base polymers, which were characterized by several techniques such as FTIR, TGA-DTA, DSC, SEM-EDX, and UV-Vis. Also, the solid-state electrical conductivities values of the compounds were measured by four-point probe technique.
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    Synthesis, characterization, thermal and electrochemical features of poly (phenoxy-imine)s containing pyridine and pyrimidine units
    (Springer, 2020) Yagmur, Hatice Karaer; Kaya, Ismet; Aydin, Haluk
    Poly (4-hydroxybenzaldehyde) was prepared by via the oxidative polymerization process in an aqueous alkaline medium by H2O2 as an oxidant. Then, poly(phenoxy-imine)s were synthesized from the condensation reactions of poly(4-hydroxybenzaldehyde) (P-4HBA) with several amines including pyridine and pyrimidine groups. The structures and characterizations of compounds were made by virtue of FT-IR, NMR, UV-Vis spectroscopy, GPC, TG, DSC, CV, SEM and fluorescence (FL) analyses. The conductivities of poly (phenoxy-imine)s were determined with electrometer by four-point probe technique. The conductivity values of poly (phenoxy-imine)s were increased to be connect with doped factor of iodine. Moreover, the electrical conductivity of the poly (phenoxy-imine)s was also measured and defined which they had semi-conductive features. Fluorescence properties of poly (phenoxy-imine)s and P-4HBA were measured out in DMF solutions to define the optimum concentrations in order to acquire the maximal FL intensities. Average molecular weight of the polymers in number (M-n), and in weight (M-w), and polydispersity index (PDI) values of poly (phenoxy-imine)s and P-4HBA were found from GPC analysis. The M-n, M-w and PDI values of P-4HBA were found to be 9900 Da (M-n), 11,300 Da (M-w) and 1.14, respectively. The electrochemical energy gap (E'(g)) and optical band gap (E-g) values of poly (phenoxy-imine)s were determined from cyclic voltammetry (CV) and UV-Vis measurements, respectively.
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    Synthesis, characterization, thermal and electrochemical properties of imine polymers containing pyridine and pyrimidine units
    (Industrial Chemistry Research Inst, 2017) Karaer, Hatice; Kaya, Ismet; Aydin, Haluk
    Schiff bases polymers were synthesized from 2-hydroxybenzaldehyde (2-HBA) vin oxidative polymerization method in an aqueous alkaline medium in the presence of NaOCI as an oxidant. Then, these polymeric Schiff bases were prepared from the polyaldehyde by grafting each of them with different amines containing pyridine and pyrimidine groups. The structures of polymers were confirmed by FT-IR, H-1 NMR, C-13 NMR, and UV-Vis measurements. The polymers were characterized by GPC and SEM analyses. Furthermore, their optical properties were determined by UV-Vis and fluorescence spectroscopy, their electrochemical properties by cyclic voltammetry (CV) analysis and solid state conductivity measurements by the four-point probe technique, their thermal behavior by TG, DTA, and DSC measurements. The electrical conductivity of the polymers was also measured and found that they are semiconductive. The number average molecular weight ((M) over bar (u)), the weight average molecular weight ((M) over bar (w)), and dispersity (D) values of the polymers were found from GPC analysis and were equal 5900, 5450 and 1.08, respectively, for poly(2-hydroxybenzaldehyde) (P-2HBA) polymer. Electrochemical energy gap (E-s) was found by CV, whereas optical band gap (E-s,) was determined by UV-Vis measurements.
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    Synthesis, characterization, thermal and electrochemical properties of poly (phenoxy-imine)s containing benzothiazole unit
    (Springer, 2023) Kaya, Ismet; Dincer, Emin; Yagmur, Hatice Karaer
    In this study, Schiff bases (SCH-1 and SCH-2) were synthesized from the condensation reaction of 2-aminobenzothiazole with 3-hydroxy-4-methoxybenzaldehyde and 3-hydroxy-4-ethoxybenzaldehyde. Poly(phenoxy-imine)s were synthesized from Schiff bases via oxidative polycondensation by NaOCl (6-14% aqueous solution) as oxidant in alkaline medium and H2O2 (35% aqueous solution) as oxidant in THF medium. The structures characterizations of Schiff bases and poly(phenoxy-imine)s were confirmed by FT-IR, 1H and 13C NMR, CV, UV-Vis and TGA analyses. Limit oxygen index (LOI) and the heat resistance index (THRI) temperature were determined from thermogravimetric measurements of compounds. P-SCH-2-A showed the highest LOI as 45.50 with self-extinguishing according to other polymers (18-30). The optical band gap of P-SCH-2-A was determined to be 1.99 eV. Additionally, the optical band gap energy of compounds were calculated by using the Tauc method. According to the Tauc method, the optical band gap (Eg) value of P-SCH-2-A was calculated to be 2.20 eV. The glass transition temperatures (Tg) and surface properties of poly(phenoxy-imine)s were determined from DSC and SEM analyses, respectively. The weight average molecular weight (Mw) values of P-SCH-1-O, P-SCH-2-O, P-SCH-1-A and P-SCH-2-A were calculated to be 7400, 8400, 3100 and 19,100 g mol-1 from gel permeation chromatography (GPC) measurements.