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    The accumulation and histological effects of organometallic fungicides Propineb and Maneb in the kidneys of fetus and female rats during pregnancy
    (Elsevier Ireland Ltd, 1998) Guven, K; Deveci, E; Akba, O; Onen, A; de Pomerai, D
    Dithiocarbamate propineb and maneb are organometal fungicides, which are widely used for the control of diseases in plants. Female Wistar rats were exposed orally to 200 and 400 ppm propineb and 250 ppm maneb, from the sixth day of gestation up to birth. We found that the body weights of both one-day old litters and their fungicide-treated mothers were lower than those of controls. Histological examination of the kidneys of fetus and fungicide-treated pregnant females showed a variety of histopathological effects. Moreover, the analysis of zinc (Zn) and manganese (Mn) concentrations (using inductively coupled plasma-atomic emission spectrometry) in the kidneys of pregnant females exposed to organometallic fungicides during pregnancy demonstrated that the metal concentrations in the kidney were higher than those of controls. However, the renal metal concentrations were significantly increased in the litters subjected to the fungicides during gestation, indicating that high levels of the trace metals in the organ of fetus may well be due to the fungicides easily passing the placental barrier. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.
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    Chemical analysis of geothermal water of Cermik, Turkey
    (Parlar Scientific Publications (P S P), 2003) Akba, O; Baysal, A; Hamamci, C; Merdivan, M; Gumgum, B
    Geothermal water of Cermik, which is located in Southeast Anatolia - Turkey, is a Na-Cl-HCO3 type containing also sulfide and iodide. The temperature, pH and flow rate of the geothermal water are 51 degreesC, 7.6 and 21 L s(-1), respectively. Its physical and chemical characterization in detail was done using standard methods. The trace elements Al, Ba, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sr and Zn were analyzed directly using inductively coupled plasma-atomic emission spectrometry due to very low detection limits and the good reproducibility of this analytical method.
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    Comparison of microwave digestion procedures for the determination of some elements in asphaltite ash using ICP-AES
    (Soc Chimica Italiana, 2002) Baysal, A; Akba, O; Merdivan, M; Hamamci, C; Gümgüm, B
    A microwave digestion procedure for asphaltite ash was developed in an attempt to facilitate routine analysis and obtain reproducible conditions or comparable results. The. conditions of the most effective procedure for 0.1g asphaltite ash samples are 1 ml of HNO3 + 3 ml of HCl + 1 ml of HF + 1 ml of deionized water as acid mixture and 15 min for digestion time. The digestion was accomplished in five stages applying continuously 90 % to 20 % of the microwave power and 20 to 100 psi of the pressure for 10 min of total time. Concentrations of selected elements, Cr, Co, Fe, Mn, Ni and Zn were measured using inductively coupled plasma-atomic emission spectroscopy. The proposed method of digestion provided precise results with relative standard deviations generally less than 3 % for investigated elements. Results for fly ash as standard reference material was in good agreement with certified values.
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    Heavy metal levels in mullet, Liza abu (Heckel, 1843) (Mugilidae) from the Tigris River, Turkey
    (Birkhauser Verlag Ag, 1996) Unlu, E; Akba, O; Sevim, S; Gumgum, B
    The heavy metal levels in the muscle, liver, gonad, gill and intestine of mullet (Liza abu) from the Tigris River in Turkey were studied. The average levels showed that concentrations of Co, Ct, Cu, Mn, Ni and Zn in the mullet varied depending on different organs. Cd and Pb were not detected while Co was detected only in intestine samples. Cr, Cu, Mn. Ni and Zn were found in all the samples analyzed. All the fish samples contain high concentrations of Co, Cr, Cu, Mn, Ni and Zn. The high concentrations of heavy metals may be directly related to the contamination of the Tigris River by a copper plant.
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    Lead in urban street dust in Diyarbakir, Turkey
    (Inst Lebensmitteltechnologie Analytische Chemie, 1997) Hamamci, C; Gumgum, B; Akba, O; Erdogan, S
    Particulate 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).
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    Matrix effects of concomitant species on the determination of nickel by inductively coupled plasma atomic emission spectrometry
    (Mrs Pushpa Agarwal, 2005) Akba, O; Baysal, A; Merdivan, M; Hamamci, C; Gumgum, B
    The interference on the determination of nickel by the salts LiCl, NaCl, KCl, CsCl, NH4Cl, Na2SO4, NaNO3, NaC2H3O2 in an inductively coupled plasma-atomic emission spectrometry has been carried out. The salt concentration was in the 100-10000 mg L-1 range. Nickel emission was enhanced at lower matrix concentrations (100 mg L-1) and was depressed at higher matrix concentrations (10000 mg L-1). Except cesium, above 100 mg L-1, all studied ions caused a decrease in the signal intensity in the range of 0-15%. The sequence order of the investigated ions for the enhancement and depression was unstable. The sequence order in enhancement was found as Li+ < Na+ < K+ < Cs+ < NH4+ for cation; NO3- < SO42- < Cl- < OAc- for anions and Cs+ < NH4+ < K+ < Li+ < Na+ for cat-ions and OAc- < SO42- Cl- < NO3- for anions in depression at the studied lines.
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    Polymer supported humic acid for separation and preconcentration of thorium(IV)
    (Taylor & Francis Inc, 2004) Erdogan, S; Merdivan, M; Hamamci, C; Akba, O; Baysal, A
    The 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.
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    Preparation and characterization of polyoxometallates of molybdenum, tungsten and their salts
    (Marcel Dekker Inc, 1997) Akba, O; Guzel, F; Yurdakoc, K; Gumgum, B; Tez, Z
    In this work, confirmation of the molecular formula and investigation of the structural stability of the prepared various types of heteropoly acids and their salts by TGA are reported. Specific surface areas of the samples were determined by the BET-single point N-2 adsorption method. Scanning electron microscopy (SEM) was used for the of surface topography of the samples in the sense of crystalline and amorphous states and the acidities of these solid samples were determined based on the color changes of suitable indicator solutions by the way of a butylamine titration method. Impurities, weight ratios and bonding states of the characteristic elements of the samples were determined from XRD, EDX and FTIR studies.
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    Pyrolysis kinetics and chemical composition of Hazro coal according to the particle size
    (Springer, 2005) Duz, MZ; Tonbul, Y; Baysal, A; Akba, O; Saydut, A; Hamamci, C
    The relationship between particle size and chemical composition of Hazro coal (origin: SE Anatolia, Turkey) has been examined by elemental analysis and by thermogravimetric pyrolysis. The chemical composition of the coal was determined by grinding sample particles physically and separating according to their size in mm by sieving. Particle size distribution of the coal and chemical composition of these fractions were given. The coal has been non-isothermally pyrolysed in a thermogravimetric analyser to determine the kinetic factors. Thermal gravimetric (TG/DTG) experiments were performed from ambient temperature to 800 degrees C under a nitrogen atmosphere at heating rate 10 K min(-1) with five different particle size ranges. Kinetic parameters of the samples were determined using a Coats and Redfern kinetic model, assuming a first-order reaction. Depending on the particle size of the coal samples, the mean activation energy values varied between 49.1 and 84.6 kJ mol(-1). The results discussed indicate that activation energies increase as the particle size decreases.
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    Synthesis of esters under microwave irradiation using heteropoly acids as catalysts
    (Springer, 2002) Öztürk, G; Gümgüm, B; Akba, O
    A practical and simple technique for synthesis of esters was developed by suing heteropoly acid as catalyst under microwave irradiation in the absence of organic solvents. Alcohols were easily and selectively converted to their acetates and benzoated with excellent yields (greater than or equal to98%), and in very short time (similar to5 min), as environmentally benign.