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51.
Şerife Saçmacı Şenol Kartal Mustafa Saçmacı 《International journal of environmental analytical chemistry》2013,93(14):1626-1637
A simple back-extraction method was developed for the separation and preconcentration of trace levels of zinc from different matrices. Ethyl-2-(4-methoxybenzoyl)-3-(4-methoxyphenyl)-3-oxopropanoylcarbamate (EMPC) was used as a new complexing agent for the extraction of zinc(II) from the aqueous sample phase to the methyl isobutyl ketone (MIBK) phase as Zn(EMPC)2 complexes. The Zn(II) can be selectively stripped with 1?mL of 0.5?mol?L?1 HCl from Mn+(EMPC)n complexes [Ag(I), Al(III), Cd(II), Cr(III), Cu(II), Fe(II), Fe(III), Mn(II), Ni(II), Pb(II) and Pd(II)] which dissolved in MIBK phase. Some experimental parameters, which are important for the whole extraction process, including pH, sample volume, shaking time, amount of the EMPC reagent, amount of MIBK, ionic strength, and type of back-extractant were investigated. The recovery for Zn(II) was greater than 95%. The detection limit of the method was found to be 0.2?µg?L ? 1 and the relative standard deviation as 6.4%. The concentrations of Zn(II) in the certified reference materials (LGC6019 river water and NIST-1547 peach leaves) by the presented method were in good agreement with the certified values. The proposed method was succesfully applied to the determination of zinc in some natural waters, rice, hair, soil, and tea samples. 相似文献
52.
Synthesis of melamine based polymer complexes and their thermal degradations and magnetic properties
Şaban Uysal 《Journal of inclusion phenomena and macrocyclic chemistry》2013,76(1-2):223-230
In this study, new polymer Fe(III) and Cr(III) complexes were synthesized. These polymer complexes were characterized by using elemental analysis, FT-IR spectroscopy, MS, thermal analyses and magnetic susceptibility measurement technics. Their thermal degradations were investigated, and co-polymerization was compared to aliphatic polymerization by using 1,2-dibromomethylbenzene and o-phenylenedialdehyde. Finally, metal ratios of the complexes were determined by using atomic absorption spectroscopy. The complexes are distorted octahedral low-spin (S = 1/2) Fe(III) and distorted octahedral (S = 3/2) Cr(III) bridged by COO? and catechol groups. 相似文献
53.
Amidoxime modified hydroxypropyl methylcellulose (HPMC) films (HPMC-g-AO) were used for the recovery of uranium from aqueous solutions by a complexation process. The adsorption experiments were carried out by immersion of a certain amount of films in UO2 2+ solutions (resultant pH 4.1) ranging in concentration from 100 to 1,000 ppm. The effect of temperature (25–50 °C) on the adsorption capacity of HPMC-g-AO was investigated at the optimized time. The adsorption kinetics and the thermodynamics as well as the adsorption capacity of HPMC-g-AO films were investigated. The adsorption capacity was found as 765 mg UO2 2+/g dry film. The kinetic and the thermodynamic parameters (i.e. activation energy, enthalpy, entropy and Gibbs free energy) for the interaction of UO2 2+ with HPMC-g-AO were calculated based on known basic relations. The results showed that adsorption occurred through strong electrostatic interactions with an enthalpy of ?36.5 kJ/mol. The desorption of UO2 2+ were investigated using different desorption agents such as EDTA, HCl, NaHCO3, and NaOH. After the 2 weeks treatment period, the highest desorption yield were found as 23 % with NaHCO3. 相似文献
54.
We report herein the synthesis of a novel class of compounds, ethyl 4-oxo-4H-furo[3,2-c]pyran-6-yl carbonate, (7E)-7-[(dimethylamino)methylene]-4H-furo[3,2-c]pyran-4,6(7H)-dione, 5-oxo-N-phenyl-2,5-dihydro-4H-furo[3,2-b]pyrrole-4-carboxamide, and 5-oxo-N-phenyl-5,6-dihydro-4H-thieno[3,2-b]pyrrole-4-carboxamide starting from the corresponding acid derivatives. Intramolecular cyclization in the presence of thionyl chloride formed the target fused ring systems. Additional transformation was seen in the cyclization of furan-fused heterocycle. A mechanism was proposed based on experimental and computational findings. 相似文献
55.
Nader Noroozi Pesyan Marziyeh Bagheri Ertan Şahin Tuncay Tunç 《Journal of the Iranian Chemical Society》2014,11(5):1429-1437
The use of DCC, triethylamine and 4-dimethylaminopyridine in dichloromethane provides a general and standard one-pot procedure for the O-acylation of cyclic β-dicarbonyl compound derivatives (1) with palmitic and stearic acids which have long hydrocarbon tails, to synthesis of new type of fatty acid derivative in good to excellent yields. Structure elucidation was carried out by FT-IR, 1H NMR and 13C NMR spectroscopy techniques. The acyl migration was also found in results and the corresponding structure was characterized by X-ray crystallography. A proposed mechanism was discussed for the formation of products. 相似文献
56.
Nader Noroozi Pesyan Mohammad Jalilzadeh Nasim Yalabi Torkaman Ertan Şahin 《Journal of the Iranian Chemical Society》2014,11(1):35-45
Reaction of symmetrical and unsymmetrical (thio)barbituric acids with aldehydes in the presence of triethylamine afforded a new form of bis-(thio)barbiturate containing charge-separated inter- and eight-membered intramolecular H-bonds. The reaction products were obtained as bis-(thio)barbiturates containing eight-membered intramolecular H-bond in the presence of l-(+)-tartaric acid (TA). The intramolecular H-bond strength (kcal/mol) and corresponding pKa value for 4ab′ were estimated to be 37 kcal/mol and ?1.3, respectively. 相似文献
57.
Hemn A. H. Barzani Hoshyar Saadi Ali Cihat Şahin Musa Kıran Yavuz Yardım 《Electroanalysis》2022,34(8):1280-1288
An effective electrochemical sensor was constructed using an unmodified boron-doped diamond electrode for determination of genistein by square-wave voltammetry. Cyclic voltammetric investigations of genistein with HClO4 solution indicated that irreversible behavior, adsorption-controlled and well-defined two oxidation peaks at about +0.92 (PA1) & +1.27 V (PA2). pH, as well as supporting electrolytes, are important in genistein oxidations. Quantification analyses of genistein were conducted using its two oxidation peaks. Using optimized experiments as well as instrumental conditions, the current response with genistein was proportionately linear in the concentrations range of 0.1 to 50.0 μg mL−1 (3.7×10−7−1.9×10−4 mol L−1), by the detection limit of 0.023 μg mL−1 (8.5×10−8 mol L−1) for PA1 and 0.028 μg mL−1 (1.1×10−7 mol L−1) for PA2 in 0.1 mol L−1 HClO4 solution (in the open circuit condition at 30 s accumulation time). Ultimately, the developed method was effectively applied to detect genistein in model human urine samples by using its second oxidation peak (PA2). 相似文献
58.
MODELING HARVEST SCHEDULING IN MULTIFUNCTIONAL PLANNING OF FORESTS FOR LONGTERM WATER YIELD OPTIMIZATION 下载免费PDF全文
HAYATI ZENGIN ÜNAL ASAN SINAN DESTAN MURAT ENGIN ÜNAL AHMET YEŞIL PETE BETTINGER AHMET SALIH DEĞERMENCI 《Natural Resource Modeling》2015,28(1):59-85
In this study, wood production and hydrologic functions of forests were accommodated within a planning procedure for separate working circles (areas dedicated to certain forest functions) that were delineated according to an Ecosystem‐Based Functional Planning approach. Mixed integer goal programming was used as the optimization technique. The timing and scheduling of a maintenance cutting (partial harvest) was the decision variable in the modeling effort, and an original formulation was developed as a multiobjective planning procedure. Four sample planning strategies were developed and model outputs were evaluated according to these strategies. Spatial characteristics of stands were considered, and used to prohibit the regeneration of adjacent stands during the same time period. Because of the positive relationship between qualified water production and standing timber volume in the forest, the model attempts to maximize qualified water production levels by increasing standing volume stocks in the forest through the delay of regeneration activities. 相似文献
59.
Ştefan Ţălu Sebastian Stach Joana Zaharieva Maria Milanova Dimitar Todorovsky Stefano Giovanzana 《International Journal of Polymer Analysis and Characterization》2014,19(5):404-421
The structural complexity of the 3-D surface of poly(methylmethacrylate) films with immobilized europium β-diketonates was studied by atomic force microscopy and fractal analysis. Fractal analysis of surface roughness revealed that the 3-D surface has fractal geometry at the nanometer scale. Poly(methylmethacrylate) (PMMA) as immobilization matrix is dense and uniform, and a tendency for formation of chain structures was observed. Fractal analysis can quantify key elements of 3-D surface roughness such as the fractal dimensions D f determined by the morphological envelopes method of the Eu(DBM)3 and Eu(DBM)3 · dpp nanostructures, which are not taken into account by traditional surface statistical parameters. 相似文献
60.
The C18H20N2O7U · 2H2O (I) complex has been prepared and characterized by single crystal X-ray diffraction properties (CIF file CCDC no. 913243). The title compound crystallizes in the orthorhombic system, space group Pbca with a = 19.542(5), b = 9.916(5), c = 21.940(5) Å, V = 4252(3) Å3 and Z = 8. In complex I, the U atom has a distorted pentagonal-bipyramidal geometry with a tetradentate Schiff base ligand and water molecule in the equatorial plane and oxo atoms in the axial positions. The crystal packing occurs intra-inter molecular hydrogen bonds. 相似文献