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Öğe Alveolar capillary membrane permeability in the patients with rheumatoid artritis(Springer-Verlag, 2001) Kaya, H; Balci, TA; Polat, M; Erdogan, S; Güllen, O[Abstract Not Available]Öğe Effect of structural modifications of diaza-18-crown-6 on the extractability and selectivity of univalent metal picrates(Elsevier Science Bv, 2001) Ziyadanogullari, B; Topal, G; Erdogan, S; Hamamci, C; Hosgoren, HThe solvent extraction of univalent metal cations with N,N'-dibenzyl-1,4,10,13-tetraoxa-7,16 diaza-2,3,11,12-dibenzocycloocta deca-2,11-diene (L-1), N,N'-didodecyl-1,4,10,13-tetraoxa-7,16-diaza-2,3-benzocylooctadeca-2-ene (L-2) and N,N'-dibenzyl-1,4,10,13-tetraoxa-7,16-diaza-2,3,11,12-dibenzocyclo octadeca-2,11-diene (L-3) with picrate anion into dichloromethane has been studied at 25 degreesC by UV-visible spectroscopy. The extractability and selectivity of univalent metal picrates (Li+, Na+, Ag+, PhCH2NH3+, NH4+) was evaluated as a function of [ligand]/[metal cation]. L-2 showed the highest extractability and selectivity for Lit over the larger studied cations, and also exhibited the highest [Li+]/[NH4+] selectivity as L/M = 1. (C) 2001 Elsevier Science B.V. All rights reserved.Öğe The effects of organic pesticides on inner membrane permeability in Escherichia coli ML35(Springer, 2005) Guven, K; Yolcu, M; Gul-Guven, R; Erdogan, S; De Pomerai, DWe have tested whether some pesticides might cause inner membrane leakage in ML35 Escherichia coli cells, which express beta-galactosidase (lacZ; EC 3.2.1.23) constitutively but lack the permease (lacY) required for substrate entry. The activity of beta-galactosidase (indicative of substrate leakage through the inner membrane) was increased by various concentrations of pesticides, including the organometallic fungicides maneb and mancozeb, the insecticide Thiodan, and the herbicide Ally, as well as by antibiotics such as ampicillin, gramicidin D, and the calcium ionophore A23187. The enzyme activity was increased by up to similar to 30% when the E. coli ML35 strain was exposed to various concentrations (between 50 and 250 ppm) of both fungicides. Thiodan had only a slight effect on beta-galactosidase activity (increase of 12.8%), whereas, among the antibiotics, the calcium ionophore at 20 mu g/ml caused a significant increase in enzyme activity by up to 61.8%. This effect is similar to that of sodium dodecyl sulfate, used as positive control (similar to 70% increase). Accumulation of maneb and mancozeb by bacterial cells was also studied taking advantage of their metal content and using atomic absorption spectrophotometry. In parallel with the increase in enzyme activity, both fungicides accumulated in the cells as a function of their concentration. Time course experiments (3, 6, and 9 h) of fungicide accumulation and of bacterial growth at various pesticide concentrations were also carried out. Maneb seems to inhibit the bacterial growth better than mancozeb. In addition, maneb uptake increases with time up to 9 h at all tested concentrations, whereas the accumulation of mancozeb is similar at all the exposure times tested. This indicates a different uptake and/or metabolizing strategy by E. coli cells for the two fungicides.Öğe Formation and characterization of humic acids from low rank anatolian coals by air oxidation(Taylor & Francis Inc, 2005) Erdogan, S; Duz, MZ; Merdivan, M; Hamamci, CThe results of this study are aimed at evaluating the effects of air oxidation time, temperature and demineralization on humic acid production from two low-rank Anatolian coals. Two Anatolian low rank coals were studied at 120 and 200degreesC up to 10 days with and without demineralization. The best results for humic acid formation were obtained at a high temperature for longer times. Demineralization effect is negligible for studied coals. The rate of humic acid formation increased at first with increase in oxidation time, reached a maximum, and then decreased at high oxidation time. Also, a detailed study of the elemental composition, the characterization by FTIR, and the acidity of humic acids are reported.Öğe Lead in urban street dust in Diyarbakir, Turkey(Inst Lebensmitteltechnologie Analytische Chemie, 1997) Hamamci, C; Gumgum, B; Akba, O; Erdogan, SParticulate matters were collected from thirteen locations in and around Diyarbakir(Turkey) in September 1995 to determine lead content. Lead analyses were performed with ICP-AES measured at 266.316 nm. The average concentrations of lead in urban street dust in Diyarbakir, Turkey was found to be 911 ppm (ranging from 616 to 1208 ppm).Öğe Polymer supported humic acid for separation and preconcentration of thorium(IV)(Taylor & Francis Inc, 2004) Erdogan, S; Merdivan, M; Hamamci, C; Akba, O; Baysal, AThe resin impregnating humic acid (HA) onto XAD-4 has been prepared to investigate adsorption behaviour of Th(IV). The characterization of the resulting resin has been carried out by infrared spectral data and sorption capacity. Maximum adsorption capacity of Th(IV) on the resin is found to be 1.51 X 10(-4) mol g(-1) at pH 4. The sorbent was found to possess a high selectivity for Th(IV) with an optimum extraction pH around 3-7. Recoveries for Th(IV) determined prior to breakthrough were found to be quantitative (96-99%). The resin exhibits good chemical stability, reuseability, and a faster rate of equilibration for Th(IV) determination. The influence of several ions as interferents is discussed. The method has been successfully applied for the separation of Th(IV) in synthetic mixtures.Öğe The solvent extraction of alkali metal picrates with 4,13-N,N?-dibenzyl-4,13-diaza-18-crown-6(Elsevier Science Bv, 1998) Hamamci, C; Hosgoren, H; Erdogan, SExtraction of alkali metal picrates with N,N'-dibenzyl-18-crown-6 was carried out, with dichloromethane as water-immiscible solvent, as a function [ligand]/[metal cation]. The extractability of metal picrates (Li+, Na+, K+ Rb+, Cs+) was evaluated as a function of [L]/[M+]. The extractability of complex cation-picrate ion pairs decreases in this sequence: Li+ > Rb+ > Cs+ > K+ > Na+. The overall extraction equilibrium constants (K-ex) for complexes of N,N'-dibenzyl-18-crown-6 with alkali metal picrates between dichloromethane and water have been determined at 25 degrees C. The values of the extraction constants (log K-ex) were determined to be 10.05, 6.83, 7.12, 7.83, 6.73 for Li+ Na+, K+, Rb+ and Cs+ compounds, respectively. DB186 shows almost 2-fold extractability against Li+ compared to the other metal picrates, whereas it shows no obvious extractability difference amongst the other metal cations when [L]/[M+] is 0.2-1. However, an increasing extractability is observed for Cs+ when [L]/[M+] [1]. (C) 1998 Elsevier Science B.V. All rights reserved.
