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Speciation of Cr(III)/Cr(VI) in Tannery Waste Waters by Using Ion-Exchange Resins
Kartal, S.,Tokalloglu, S.,Ozkan, B. Korean Chemical Society 2006 Bulletin of the Korean Chemical Society Vol.27 No.5
A method has been described for the chemical speciation, preconcentration and determination of Cr(III) and Cr(VI) species in filtered tannery waste waters by flame atomic absorption spectrometry using ion-exchange resins. Amberlite IR-120($H^+$) strongly acidic cation exchanger and Amberlite IRA-410($CI ^-$) strongly basic anion exchanger resins were used for the separation and preconcentration of Cr(III) and Cr(VI) species, respectively. Optimum condition for preconcentration and speciation was obtained by testing pH of sample and eluent, flow rates of sample and eluent, amount of resins, volume of sample and eluents, and effect of foreign ions. The recommended method has been successfully applied for the preconcentration and determination of chromium species in the dissolved phase of waste water samples collected from a tannery waste water treatment plant in Kayseri, Turkey. The detection limits achieved were 0.73 $\mu$g/L for Cr(III) and 0.81 $\mu$g/L for Cr(VI). Recovery studies showed 99% for Cr(III) and 98% for Cr(VI), for samples spiked with single species.
Yusuf Kartal,Ovun Isin 한국자동차공학회 2019 International journal of automotive technology Vol.20 No.3
For developing automotive industry, one of the focusing point is reduction of engine friction level to decrease both engine emissions and fuel consumption. Important part of researchers have focused on cold engine start period, which has higher friction loses. Shorter warm up period and faster heating of engine oil help to provide better engine performance. Not only warm up time but also better cool down period after engine stops, dramatically effects engine efficiency. If oil temperature stays hot for longer time during the vehicle key-off duration, it brings an important advantageous at the next start. Main purpose of this study is to investigate oil temperature changes depending on the design parameters of the oil pan. This investigation is done for oil warm up and cool down periods by mathematical model, which is validated for 2.0 L and 4 cylinders diesel engine. Design improvement combinations against base steel oil pan has been examined throughly in terms of oil temperature changes, warm up and cool down time, frictional loses and weight reduction opportunity. As a result, 5 mm thickness plastic oil pan with windage tray application is the best solution option since it brings both 12.5 % friction decreasing in cold start after 2 hours key-off duration, and 43 % weight reduction.
Fatma Kartal,Kerim Uğur,Burak Mete,Mehmet Emin Demirkol,Lut Tamam 대한신경정신의학회 2022 PSYCHIATRY INVESTIGATION Vol.19 No.3
Objective In this study, it is aimed to investigate the relationship between the oxytocin level and the rejection sensitivity, childhood mental traumas, and attachment styles in patients diagnosed with borderline personality disorder (BPD).Methods Participants between the ages of 18–30 were included in the study. The patient group consists of 31 participants and the healthy control group consists of 31 participants. Sociodemographic/Clinical Variables Questionnaire, Relationship Scales Questionnaire, Rejection Sensitivity Questionnaire and Childhood Trauma Questionnaire were administered to the participants included in the study. Serum oxytocin levels of the participants were measured using the Elisa method.Results The oxytocin levels were found to be significantly lower in patients with BPD than in healthy control subjects, whereas the rejection sensitivity and childhood traumas were found to be significantly higher. No difference was found between the patient and control groups in terms of attachment styles, yet it was determined that there may be differences between the oxytocin levels of the BPD patients according to the attachment styles the patients have.Conclusion In conclusion, the findings of this study revealed that the rejection sensitivity in BPD patients is not associated with oxytocin levels and childhood traumas, indicating the need to assess the BPD patients in terms of other biopsychosocial factors related to the etiopathogenesis of BPD.
Plasmapheresis in a Patient With "Refractory" Urticarial Vasculitis
Ozgur Kartal,Mustafa Gulec,Zafer Caliskaner,Oral Nevruz,Turker Cetin,Osman Sener 대한천식알레르기학회 2012 Allergy, Asthma & Immunology Research Vol.4 No.4
Immune complexes are found in the circulation of 30%-75% of patients with urticarial vasculitis and much evidence supports the role of these immune complexes in the pathogenesis of urticarial vasculitis. Plasmapheresis is effective for removing these immune complexes; however, there are few reports on the use of plasmapheresis in the treatment of urticarial vasculitis. We describe a case of “refractory” urticarial vasculitis in which the symptoms improved after plasmapheresis treatment. We suggest that plasmapheresis be considered as an option in patients with severe or treatment-resistant urticarial vasculitis.
How Main Stock Exchange Indices React to Covid-19 Pandemic: Daily Evidence from East Asian Countries
Mustafa Tevfik Kartal 연세대학교 동서문제연구원 2021 Global economic review Vol.50 No.1
This study investigates whether the Covid-19 and the financial indicators affect the main stock exchange indices of East Asian countries. Number of cases and deaths caused by Covid-19, uncertainty, volatility, foreign exchanges, and mobility are examined by using Quantile Regression and comparing the pre-pandemic and the pandemic periods. The results shows that (i) the indicators have a significant negative impact as expected; (ii) the impact of mobility and pandemic indicators has significance in the trend of the indices whereas they differentiate among countries; (iii) the impact of the variables is significantly differentiated from the low level to the high level.
Tokalloglu, Serife,Kartal, Senol Korean Chemical Society 2006 Bulletin of the Korean Chemical Society Vol.27 No.9
In this study, a solid phase extraction method has been developed for the preconcentration and separation of the elements Cr(III), Fe(III), Co(II) and Pb(II) at trace levels by using a column packed with Amberlite XAD-1180 resin loaded with 4-(2-pyridylazo)-resorcinol (PAR) reagent. After preconcentrating, the metals retained on the column were eluted with 20 mL of 3 mol/L $HNO_3$ and then determined by flame atomic absorption spectrometry (FAAS). The factors affecting the recovery of the elements, such as pH, type and concentration of eluent, volume of sample and elution solution, and matrix components, were also ascertained. The recoveries of Cr(III), Fe(III), Co(II) and Pb(II) were found to be $99\;{\pm}\;4,\;97\;{\pm}\;3,\;95\;{\pm}\;3$ and $98\;{\pm}\;4$%, respectively, under the optimum conditions at 95% confidence level and the relative standard deviations found by analyzing of nine replicates were $\leq4.4$%. The preconcentration factors for Cr(III), Fe(III), Co(II) and Pb(II) were found as 75, 125, 50 and 75 respectively. The detection limits (DL, 3s/b) were 3.0 $\mu g/L$ for Cr(III), 1.25 $\mu g/L$ for Fe(III), 3.3 $\mu g/L$ for Co(II), and 7.2 $\mu g/L$ for Pb(II). The recoveries achieved by adding of metals at known concentrations to samples and the analysis results of Buffalo river sediment (RM 8704) show that the described method has a good accuracy. The proposed method was applied to tap water, stream water, salt and street dust samples.
Tokalioglu, Serife,Kartal, Senol,Elci, Latif Korean Chemical Society 2002 Bulletin of the Korean Chemical Society Vol.23 No.5
A method has been described for the determination of Cu(Ⅱ), Pb(Ⅱ), Ni(Ⅱ), Cd(Ⅱ), Mn(Ⅱ) and Fe(Ⅲ) by flame atomic absorption spectrometry (FAAS) after preconcentration on Amberlite XAD-16 resin, using hexamethyleneammonium-hexamethylenedithiocarbamate (HMA-HMDTC) as a chelating agent, and NH3/NH4Cl buffer solution (pH 9). Influences of various analytical parameters such as pH, concentration of nitric acid, amount of analytes, diverse ions and sample volume were investigated. The relative standard deviation (RSD) and the detection limit (LOD) were found in the range of 0.8-2.9% and 0.006-0.277 ㎍/mL,respectively. Recoveries obtained by the column method were quantitative ( >95%) at optimum conditions.The method was applied to the determination of some metal ions in seawater and wastewater samples. A high preconcentration factor (about 150 for seawater and 75 for wastewater samples) and simplicity are the main advantages of this suggested method.