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    Hydration process of zeolite-rich tuffs and siltstone-blended cement pastes at low W/B ratio, under wet curing condition
    (Taylor & Francis Ltd, 2014) Heriberto Cornejo, Mauricio; Elsen, Jan; Baykara, Haci; Paredes, Cecilia
    An extensive study in blended cement pastes that comprised two different experimental settings was carried out so as to analyse the hydration process and compressive strength evolution up to 91 days. The aim of this study was to understand the hydration process using zeolite-rich tuffs and siltstone as supplementary cementitious materials at low water-to-binder ratio (W/B = .3) under wet curing condition. It was observed that there were two competing reactions, i.e. pozzolanic reaction and carbonation, during the hydration process, thus leading to a decrease in the content of calcium hydroxide (CH); however, carbonation played a more important role than the pozzolanic reaction in consuming it at the given W/B ratio. The total amount of CH consumed by pozzolanic reaction was likely around 8%, while carbonation transformed around 19% of the total amount of CH at 91 days. Although fully hydrated cement paste incorporates .23 g of water per g of cement, only 60% of this value was used at such a W/B ratio. In addition, the amount of normalised water in hydrates increased as the dosage increased by factor of .158% per 1% of dosage. Finally, the optimal dosages at which Zeo1, Zeo2 and Limo showed the highest compressive strength were in the ranges of 12.5-15%, 17.5-20% and 10-12.5%, respectively .
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    Investigation of the Effect of Some Optically Active Imine Compounds on the Enzyme Activities of hCA-I and hCA-II under In Vitro Conditions: An Experimental and Theoretical Study
    (Wiley, 2016) Tektas, Osman; Akkemik, Ebru; Baykara, Haci
    Inhibitors of carbonic anhydrase (hCA; EC 4.2.1.1) are used as medicines for many diseases. Therefore, they are very important. In this study, a known series of Schiff bases were synthesized and their effects on the activities of hCA-I and hCA-II, which are cytosolic isoenzymes of carbonic anhydrase, were investigated under in vitro conditions. The synthesized compounds (H1, H2, H3, and H4) were found to cause inhibition on enzyme activities of hCA-1 and hCA-II. IC50 values of H1, H2, H3, and H4 compounds were 140, 88, 201, and 271 M for hCA-I enzyme activity and 134, 251, 79, and 604 M for hCA-II enzyme activity, respectively. The synthesized Schiff bases were characterized by several methods, including H-1 NMR, FT-IR, elemental analysis, and polarimetric measurements. Correlation coefficient square values (R-2) of comparison of the theoretical and experimental H-1 NMR shifts for H1, H2, H3, and H4 compounds were found as 0.9781, 0.9814, 0.9758, and 0.8635, respectively.
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    Synthesis and characterization of 1,2-bis(2-(5-bromo-2-hydroxybenzilidenamino)-4-chlorophenoxy)ethane and its metal complexes: An experimental, theoretical, electrochemical, antioxidant and antibacterial study
    (Pergamon-Elsevier Science Ltd, 2014) Ilhan, Salih; Baykara, Haci; Oztomsuk, Abdussamet; Okumus, Veysi; Levent, Abdulkadir; Seyitoglu, M. Salih; Ozdemir, Sadin
    A new Schiff base ligand was synthesized by reaction of 5-bromosalicylaldehyde with 1,2-bis(4-chloro-2-aminophenoxy)ethane. Then the Schiff base complexes were synthesized by the reaction of metal salts and the novel Schiff base. The molar conductivity properties of the complexes were studied and found out that the complexes are nonelectrolytes. The structures of the ligand and its metal complexes were characterized by elemental analysis, FT-IR, UV-VIS, magnetic susceptibility measurements, molar conductivity measurements, and thermal gravimetric analysis. In addition antioxidant, theoretical NMR studies and cyclic voltammetry of the complexes were done. Two methods namely metal chelating activity and diphenylpicrylhydrazyl (DPPH) radical scavenging method were used to determine the antioxidant activity, and antibacterial properties of the compounds were also studied. (C) 2013 Elsevier B.V. All rights reserved.
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    Synthesis and characterization of 1,2-bis(2-(5-bromo-2-hydroxybenzilidenamino)-4-chlorophenoxy)ethane ant its metal complexes:An experimental, theoretical, electrochemical, antioxidant and antibacterial study
    (Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2014) İlhan, Salih; Baykara, Haci; Tomsuk, Abdussamet; Okumuş, Veysi; Levent, Abdulkadir; Seyitoğlu, Salih; Özdemir, Sadin
    A new Schiff base ligand was synthesized by reaction of 5-bromosalicylaldehyde with 1,2-bis(4-chloro-2- aminophenoxy)ethane. Then the Schiff base complexes were synthesized by the reaction of metal salts and the novel Schiff base. The molar conductivity properties of the complexes were studied and found out that the complexes are nonelectrolytes. The structures of the ligand and its metal complexes were characterized by elemental analysis, FT-IR, UV–VIS, magnetic susceptibility measurements, molar conductivity measurements, and thermal gravimetric analysis. In addition antioxidant, theoretical NMR studies and cyclic voltammetry of the complexes were done. Two methods namely metal chelating activity and diphenylpicrylhydrazyl (DPPH) radical scavenging method were used to determine the antioxidant activity, and antibacterial properties of the compounds were also studied.
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    Synthesis and characterization of a new di-functional ligand and its metal complexes: an experimental, theoretical, cyclic voltammetric and antimicrobial study.
    (Synthesis and Reactivity in Inorganic, Metal-Organic & Nano Metal Chemistry, 2015) Baykara, Haci; İlhan, Salih; Tomsuk, Abdussamet; Seyitoğlu, Salih; Levent, Abdulkadir; Okumuş, Veysi; Dündar, Abdurrahman
    A new difunctional Schiff base ligand and its some metal complexes were synthesized. The compounds were characterized by elemental analysis, 1H-NMR, 13C-NMR, FT-IR, UV-VIS, magnetic susceptibility measurements, molar conductivity measurements, and thermal gravimetric analysis techniques. Additionally, DPPH scavenging, metal chelating and antibacterial activity of compounds were examined via in vitro methods. The lowest DPPH scavenging activity observed by Co(II) as 36.28% and highest was ligand as 52.00%. A cyclic voltammetric study was also carried out to determine redox potentials of the compounds. Some theoretical studies such as 1H-NMR, HOMO-LUMO, and mapped electron density of the ligand were also carried out successfully.
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    Synthesis and Characterization of a New Difunctional Ligand and Its Metal Complexes: An Experimental, Theoretical, Cyclic Voltammetric, and Antimicrobial Study
    (Taylor & Francis Inc, 2015) Baykara, Haci; Ilhan, Salih; Oztomsuk, Abdussamet; Seyitoglu, M. Salih; Levent, Abdulkadir; Okumus, Veysi; Dundar, Abdurrahman
    A new difunctional Schiff base ligand and its some metal complexes were synthesized. The compounds were characterized by elemental analysis, H-1-NMR, C-13-NMR, FT-IR, UV-VIS, magnetic susceptibility measurements, molar conductivity measurements, and thermal gravimetric analysis techniques. Additionally, DPPH scavenging, metal chelating and antibacterial activity of compounds were examined via in vitro methods. The lowest DPPH scavenging activity observed by Co(II) as 36.28% and highest was ligand as 52.00%. A cyclic voltammetric study was also carried out to determine redox potentials of the compounds. Some theoretical studies such as H-1-NMR, HOMO-LUMO, and mapped electron density of the ligand were also carried out successfully.
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    Synthesis, characterization and experimental, theoretical, electrochemical, antioxidant and antibacterial study of a new schiff base and its complexes
    (Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2014) Baykara, Haci; İlhan, Salih; Levent, Abdulkadir; Seyitoğlu, Salih; Özdemir, Sadin; Okumuş, Veysi; Tomsuk, Abdussamet; Cornejo, Mauricio
    A new Schiff base ligand was synthesized by reaction of salicylaldehyde with 1,6-bis(4-chloro-2-aminophenoxy) hexane. Then the Schiff base complexes were synthesized by metal salts and the Schiff base. The metal to ligand ratio of metal complexes was found to be 1:1. The Cu(II) complex is proposed to be square planar and the Co(II), Ni(II), Mn(II) and Zn(II) complexes are proposed to be tetrahedral geometry. The Ti(III) and V(III) complexes are proposed to be a capped octahedron in which a seventh ligand has been added to triangular face. The complexes are non-electrolytes as shown by their molar conductivities (KM). The structure of metal complexes is proposed from elemental analysis, FT-IR, UV–vis, magnetic susceptibility measurements, molar conductivity measurements, Mass Spectra and thermal gravimetric analysis. In addition antimicrobial and antioxidant studies, cyclic voltammetry of the complexes, theoretical 1H NMR and HOMO–LUMO energy calculations of the new di-functional ligand were done.
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    Thermomechanical treatment of two Ecuadorian zeolite-rich tuffs and their potential usage as supplementary cementitious materials
    (Springer, 2014) Cornejo, Mauricio H.; Elsen, Jan; Paredes, Cecilia; Baykara, Haci
    Two Ecuadorian zeolite-rich tuffs, coded as Zeo1 (Mordenite) and Zeo2 (Clinoptilolite-Heulandite-Mordenite), were treated and used as supplementary cementitious materials (SCM) so as to study the effect of the thermal and mechanical treatments on pozzolanic reaction in mortars. The treatment was carried out by means of thermomechanical process according to a central composite-blocked cube-star experimental design. In this experimental design as independent factors the milling time (48, 60, 90, 120 and 132 min) and the heating temperatures (559, 600, 700, 800 and 841 A degrees C) were used but keeping a constant heating time (5 h), and zeolite-rich tuffs as experimental blocks. The proportion of SCM was kept constant i.e. 15 %. On the other hand, the compressive strength, fixed lime, normalized water in hydrates and mg Ca(OH)(2) per mg Cement at 7, 28 and 45 days, as well as hydration products related to dehydration degree of the zeolitic tuffs (DOD) were used as dependent factors. In addition, Quantitative and High-temperature chamber XRD, TG-DSC, particle size distribution and SEM-EDS were also carried out. The most significant factor was calcination leading to increase in the compressive strength compared to control, but just up to 800 A degrees C because of recrystallization. As a conclusion, a meaningful loss of crystal structure of zeolites was not observed; but instead, the treatment could only lead to removing the water in cages and voids, thus improving the reaction with Ca(OH)(2), producing more hydrates. In addition, lime was not only fixed by pozzolanic reaction, but also by carbonation.