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A theoretical analysis of the explanation of the significant differences in antiferromagnetic interactions between homologous μ-alkoxo and acetate bridged dicopper(II) complexes: ab initio and semi-empirical calculations
(Elsevier, 2004-07) Zeyrek, C. Tuğrul; Elmalı, Ayhan; Elerman, Y.; 0000-0001-6744-7841; TAEK-ANAEM
A magnetostructural classification of dimmers, containing the Cu (μ-alkoxo) Cu core, based on data obtained from X-ray diffraction analysis reported in the literature has been performed. In these complexes, the local geometry around the copper ions is generally a square planar and each copper ion is surrounded by one N atom and three O atoms. The influence of the overlap interactions between the bridging ligands and the metal (Cu) d orbitals on the super-exchange coupling constant has been studied by means of ab initio Restricted Hatree–Fock molecular orbital calculations. The interaction between the magnetic d orbitals and highest occupied molecular orbitals of the acetate oxygens has been investigated in homologous μ-acetato-bridged dicopper(II) complexes which have significantly different −2J values (the energy separation between the spin-triplet and spin-singlet states). In order to determine the nature of the fronter orbitals, Extended Hückel molecular Orbital calculations are also reported. Ab initio restricted Hartree–Fock calculations have shown that the acetato bridge and the alkoxide bridge contribute to the magnetic interaction countercomplementarily to reduce antiferromagnetic interaction.
An EPR study of clinoptilolite from Bigadiç in Turkey
(Elsevier, 2016-01) Bıyık, Recep; Tapramaz, Recep; 0000-0001-7929-4395; TAEK-ÇNAEM
Natural and synthetic zeolites are industrial materials. They are used in many applications as food additives, molecular sieve to trap unwanted ingredients, as heavy metallic ions and groups, as shielding against radiations etc. EPR spectroscopy is a tool to characterize paramagnetic centers and radicals in the zeolite and clay type minerals. In this study natural cliptonilolite obtained from a mine in Bigadiç in western Anatolia, Turkey, was studied using electron paramagnetic resonance spectroscopy (EPR) at room temperature in natural form,following treatment of the samples: adsorbing of CO2, H2S, and SO2 gases, [Cu(H2O)6]2 ions and exposure to gamma rays. Mn atoms become paramagnetic Mn2+ ions when CO2 and H2S gases are adsorbed to clinoptilolite and when SO2 gas is adsorbed the system becomes unstable and the structure of the paramagnetic center changes with time. When Cu2+ ions are adsorbed to the Bigadiç clinoptilolite, the values of the EPR parameters are consistent with the distorted octahedral symmetry environment and after the exposure to gamma rays from a Co-60 source gives O23- radical.
An EPR study on tea: Identification of paramagnetic species, effect of heat and sweeteners
(Elsevier, 2009-10) Bıyık, Recep; Tapramaz, Recep; 0000-0001-7929-4395; TAEK-ÇNAEM
Tea (Camellia Sinensis) is the most widely consumed beverage in the world, and is known to be having therapeutic, antioxidant and nutritional effects. Electron paramagnetic resonance (EPR) spectral studies made on the tea cultivated along the shore of Black Sea, Turkey, show Mn2+ and Fe3+ centers in green tea leaves and in black tea extract. Dry black tea flakes and dry extract show additional sharp line attributed to semiquinone radical. The origins of the paramagnetic species in black tea are defined and discussed. Effect of humidity and heat are investigated. It is observed that dry extract of black tea melts at 100 ◦C and the semiquinone radical lives up to 140 ◦C while Mn2+ sextet disappears just above 100 ◦C in tea extract. Natural and synthetics sweeteners have different effects on the paramagnetic centers. White sugar (sucrose) quenches the Mn2+ and semiquinone lines in black tea EPR spectrum, and glucose, fructose, lactose and maltose quench Fe3+ line while synthetic sweeteners acesulfam potassium, aspartame and sodium saccharine do not have any effect on paramagnetic species in tea.
Application of CNUREAS and MCNP5 codes to VVER-1000 MOX core computational Benchmark
(Elsevier, 2015) Şentürk Lüle, Senem; Özdemir, Levent; Erdoğan, Adem; TAEK-ÇNAEM
In order to strengthen the nuclear design calculation capacity in Turkey, CNUREAS (Cekmece Nuclear Reactor System) was developed to provide easy usage of neutronic and thermal hydraulic nuclear codes included in the CNUREAS package. It was tested and used for research reactors and PWR type power reactors. Modifications were performed to add hexagonal geometry support taking into account VVER type reactors employing hexagonal fuel assemblies that will be built in Turkey. “VVER-1000 MOX Core Computational Benchmark” was used to test new features of the CNUREAS. The maximum deviation in effective multiplication factor results of CNUREAS was 0.7% with deterministic codes and 1.5% with Monte Carlo codes. It was concluded that CNUREAS can be used for neutronic calculations of VVER type power reactors with appropriate cross section libraries and deterministic and Monte Carlo techniques give comparable results when both provided with appropriate cross section libraries.
Effect of particle size on TL dosimetric properties of household salt
(Elsevier, 2017-07) Yüce, Ülkü Rabia; Engin, Birol; TAEK-SANAEM
This work investigates the effect of particle size in the thermoluminescence (TL) response of household salt that classified into five size fractions between 63 and 250 µm. Irradiation induced two TL peaks at 110°C and 240°C for each particle size fraction. Besides these peaks, two additional glow peaks were also observed at 80°C and 300°C for small particle size fractions < 90µm. The complexity of the glow curve pattern increased with decreasing particle size (<125 µm). The intensity of the dosimetric TL peak at 240°C increases with increasing particle size. The maximum beta radiation sensitivity of salt samples was obtained for the particle sizes of 125-180 µm and 180-250 µm. For different particle sizes, the stability of dosimetric TL peak at room temperature was studied over a storage period of 30 days.The kinetic parameters of dosimetric TL peak were determined at different particle sizes using the initial rise (IR), peak shape (PS) and variable heating rate (VHR) methods and the results are discussed in detail. Moreover, the variations of the glow peaks depending on the heating rate were also studied.
EPR spectra of Cu2+ in KH2PO4 single crystals
(Elsevier, 2007-03-18) Bıyık, Recep; Tapramaz, Recep; TAEK-ÇNAEM
Cu2+ doped single crystals of KH2PO4 were investigated using EPR technique at room temperature. The spectra of the complex contains large number of overlapping lines. Five sites are resolved and four of them are compatible with the tetragonal symmetry, and the fifth one belongs to an interstitial site. The results are discussed and compared with previous studies. Detailed investigation of the EPR spectra indicate that Cu2+ substitute with K+ ions. The principal values of the g and hyperfine tensors and the ground state wave function of Cu2+ ions are obtained.
Investigation of gamma irradiation and storage period effects on the nutritional and sensory quality of chickpeas, kidney beans and green lentils
(Elsevier, 2017) Aylangan, Ayça; Özyardımcı, Berna; İç, Erhan; TAEK-SANAEM
The objectives of this study were to determine the effects of gamma irradiation and storage period on the content of the total carotenoids, the oligosaccharides raffinose and stachyose, and the vitamins thiamine (B1) and riboflavin (B2) in pulses. Chickpea, kidney bean and green lentil samples were subjected to gamma irradiation doses of 0.25, 0.50 and 1.0 kGy followed by storage at room temperature for 12 months. The total carotenoids content was measured by spectrophotometer. Raffinose and stachyose were determined by high-performance liquid chromatography (HPLC) with refraction index detection and thiamine and riboflavin concentrations by HPLC with fluorescence detection. The impact of the irradiation dose can be seen in the result of the total carotene tests for lentils. The three different irradiation doses applied did not have significant effects on the levels of riboflavin and thiamine. The effect of the storage period was found to be significant on the raffinose and stachyose content but there were no significant changes following the applied irradiation doses. In the sensory evaluation the testers were not be able to differentiate between the 0.25, 0.50 and 1 kGy applied irradiation doses and the unirradiated samples. The results of these studies suggest that irradiation with 1.0 kGy gamma rays cause tolerable losses in the nutrients studied in chickpeas, kidney beans and green lentils.
Magnetic characterization, synthesis and crystal structure of a heterodinuclear CuIIGdIII Schiff base complex bridged by the two phenolic oxygen atoms
(Elsevier, 2005-04) Zeyrek, C. Tuğrul; Elmalı, Ayhan; Elerman, Y.; 0000-0001-6744-7841; TAEK-ANAEM
A novel heterodinuclear complex formed by the reaction of gadolinium nitrate with Schiff base complex of copper(II) has been synthesized and characterized. Preparation, crystal structure and magnetic properties of the heterodinuclear complex, LCu(Me2CO)Gd(NO3)3, (L=(N,N′-bis(2,3-dihydroxybenzylidene)-1,3-diaminopropane) are reported. The complex is consisting of a deca-coordinated GdIII ion which is bridged to four coordinated CuII via both phenolate oxygen atoms of the L Schiff base ligand. The average Cu⋯Gd separation is 3.475(2) Å. There is also one non-coordinating acetone molecule in the crystal structure. The magnetic susceptibility of the complex was measured over the range 4.5–350 K and the observed data were successfully simulated by the equation based on the spin-Hamiltonian operator H=−JSCu·SGd. The values of the intrachain interaction parameters have been deduced from the magnetic data: exchange integral J(Cu–Gd)=7.3 cm−1, gCu=2.17, gGd=2.09. This indicates a weak ferromagnetic spin exchange interaction between CuII and GdIII ions. The nature of the magnetic super-exchange interaction of the title compound is compared with similar CuIIGdIII heterodinuclear complexes.
Measurement of enhanced radium isotopes in oil production wastes in Turkey
(Elsevier, 2015-03) Parmaksız, Aydın; Ağuş, Yusuf; Bulgurlu, Figen; Bulur, Emine; Öncü, Tolga; Özkök, Yücel Özer; AAH-5187-2020; /0000-0003-4000-5175; TAEK-SANAEM
Gamma dose rates of oil production equipment and wastes were measured externally by survey meter. They were found to be between 0.2 μSv h−1 and 25.7 μSv h−1. Activity concentrations of radium isotopes in crude oil, scale, sludge, contaminated soil and water samples were determined by gamma spectrometric method. Activity concentrations of 224Ra, 226Ra and 228Ra in samples varied from MDA to 132,000 Bq kg−1. Radium isotopes enriched up to 14,667 times in scale samples. The highest value of 226Ra was found to be 35,122 ± 1,983 Bq kg−1 for sludge samples. Activity concentrations of a considerable number of samples were found to be higher than the exemption level recommended by IAEA. Measurement results revealed that oil production wastes caused soil contamination up to 70,483 Bq kg−1. They may pose a radiological risk for workers and members of the public.
Metabolite profiling of four Tunisian Eucalyptus essential oils and assessment of their insecticidal and antifungal activities
(Elsevier, 2023-11-16) Khedri, Sana; Khammassi, Marwa; Bouhachem, Sonia Boukhris; Pieracci, Ylenia; Mabrouk, Yassine; Seçer, Emine; Amri, Ismail; Flamini, Guido; Hamrouni, Lamia
Aphids (Aphidoidea) and Fusarium spp. are widely recognized as destructive pests that cause significant damage to crops on a global scale. This study aimed to ascertain the chemical composition of essential oils (EOs) of four Tunisian Eucalyptus species and evaluate their toxicity against common aphids and phytopathogenic fungi. The EOs were obtained via hydrodistillation and subsequently analyzed using GC-MS. The chemical composition analysis revealed the presence of five distinct chemical classes in the EOs: monoterpene hydrocarbons (3.8–16.7 %), oxygenated monoterpenes (5.5–86.0 %), sesquiterpene hydrocarbons (0.2–2.2 %), oxygenated sesquiterpenes (4.2–86.7 %), and non-terpene derivatives (0.1–14.1 %).Hierarchical clustering analysis (HCA) and principal component analysis (PCA) of the Eucalyptus leaf EOs highlighted significant differences among them, leading to the generation of distinct HCA clades representing at least twelve major components. The statistical analysis clearly demonstrated a dose-response relationship, indicating the impact of the tested EOs on the growth of insects and fungal mycelium. The observed effects varied due to the variability in the chemical compositions of the EOs. Notably, among the EOs tested, Eucalyptus lesoufii Maiden exhibited particularly potent effects against the targeted insect and fungal species. This research contributes to the ongoing explo- ration of natural alternatives to chemical pesticides, providing further insights for potential in- dustrial applications. It underscores the versatility of these EOs and their potential as valuable candidates in strategies for pest and disease management.
Synthesis, characterization, and evaluation of (E)-methyl 2-((2-oxonaphthalen-1(2H)-ylidene)methylamino)acetate as a biological agent and an anion sensor
(Elsevier, 2016) Zeyrek, C. Tuğrul; Boyacıoğlu, Bahadır; Yıldız, Mustafa; Ünver, Hüseyin; Yolal, Devrim; Demir, Neslihan; Elmalı, Ayhan; Aslan, Kadir; 0000-0001-6744-7841; TAEK-ANAEM
An amino acid derived and bidentate Schiff base, (E)-methyl 2-((2-oxonaphthalen-1(2H)-ylidene)methylamino)acetate (ligand), was synthesized from the reaction of glycine-methyl ester hydrochloride with 2-hydroxy-1-naphthaldehyde. Characterization of the ligand was carried out using theoretical quantum-mechanical calculations and experimental spectroscopic methods. The molecular structure of the compound was confirmed using X-ray single-crystal data, NMR, FTIR and UV-Visible spectroscopy, which were in good agreement with the structure predicted by the theoretical calculations using density functional theory (DFT). Antimicrobial activity of the ligand was investigated for its minimum inhibitory concentration (MIC) to several bacteria and yeast cultures. UV-visible spectroscopy studies also shown that the ligand can bind calf thymus DNA (CT-DNA) electrostatic binding. In addition, DNA cleavage study showed that the ligand cleaved DNA without the need for external agents. Energetically most favorable docked structures were obtained from the rigid molecular docking of the compound with DNA. The compound binds at the active site of the DNA proteins by weak non-covalent interactions. The colorimetric response of the ligand in DMSO to the addition of equivalent amount of anions (F-, Br-, I-, CN-, SCN-, ClO4-, HSO4-, AcO-, H2PO4-, N3- and OH-) was investigated and the ligand was shown to be sensitive to CN- anion.

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