WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7150
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Article Citation - WoS: 4Citation - Scopus: 7Determination of Aluminum Rolling Oil Additives and Contaminants Using Infrared Spectroscopy Coupled With Genetic Algorithm Based Multivariate Calibration(Elsevier Ltd., 2010) Yalçın, Ayşegül; Ergün, Didem; İnanç Uçar, Özlem; Özdemir, DurmuşGenetic algorithm based multivariate calibration models were generated for infrared spectroscopic determination of aluminum rolling oil additives and contaminants such as gear and hydraulic oils. Two different additives and six different suspected contaminants were investigated in the base oil lubricant. Routine analysis samples from 9 different aluminum rolling systems were collected in a period of 2 months in an aluminum rolling plant and gas chromatography (GC) is used as the reference method. Infrared absorbance spectra of the samples were then collected and the reference values obtained with GC were used together with these spectra for model building. Inverse least squares method was optimized with a genetic algorithm by selecting the most contributing regions of the infrared spectra for each component. The R2 values between GC and multivariate spectroscopic determinations were around 0.99 indicating a good correlation between the two methods. Performance of genetic algorithm based multivariate calibration models were also compared with partial least squares (PLS) method. The study showed that infrared spectroscopy coupled with multivariate calibration can be used for continuous monitoring of additives and contaminants in aluminum rolling oil. By this way, analysis time is significantly reduced and simultaneous determination of all the components can be accomplished. © 2010 Elsevier B.V. All rights reserved.Article Citation - WoS: 20Citation - Scopus: 24Preparation and Characterization of Sodium Dodecyl Sulfate Doped Polypyrrole Solid Phase Micro Extraction Fiber and Its Application To Endocrine Disruptor Pesticide Analysis(Elsevier Ltd., 2013) Korba, Korcan; Pelit, Levent; Okçu Pelit, Füsun; Özdokur, K. Volkan; Ertaş, Hasan; Eroğlu, Ahmet Emin; Ertaş, Fatma NilA robust in house solid-phase micro extraction (SPME) surface has been developed for the headspace (HS)-SPME determination of endocrine disruptor pesticides, namely, Chlorpyrifos, Penconazole, Procymidone, Bromopropylate and Lambda-Cyhalothrin in wine sample by using sodium dodecylsulfate doped polypyrrole SPME fiber. Pyrrole monomer was electrochemically polymerized on a stainless steel wire in laboratory conditions in virtue of diminishing the cost and enhancing the analyte retention on its surface to exert better selectivity and hence the developed polymerized surface could offer to analyst to exploit it as a fiber in headspace SPME analysis. The parameters, mainly, adsorption temperature and time, desorption temperature, stirring rate and salt amount were optimized to be as 70°C and 45min, 200°C, 600rpm and 10gL-1, respectively. Limit of detection was estimated in the range of 0.073-1.659ngmL-1 for the pesticides studied. The developed method was applied in to red wine sample with acceptable recovery values (92-107%) which were obtained for these selected pesticides.Article Citation - WoS: 4Citation - Scopus: 4A Chromatographic Study of Carbon Monoxide Adsorption on a Clinoptilolite-Containing Natural Zeolitic Material(Taylor and Francis Ltd., 2004) Narin, Güler; Yılmaz, Selahattin; Ülkü, SemraIn this study, the equilibrium and kinetic parameters for CO adsorption on clinoptilolite-rich natural zeolitic material were determined by the concentration pulse chromatography technique. Experiments were carried out at different column temperatures (60-120°C) and interstitial carrier gas velocities (3.1-16.3 cm/s) using a clinoptilolite-rich natural zeolitic material packed column. The equilibrium and kinetic parameters were determined by matching the moments of the experimentally obtained response curves to the parameters in the mathematical model. The Henry's Law constants were found to decrease from 700 to 49 with increasing temperature. The heat of adsorption at low coverage was found to be 50.73 kJ/molK. The contributions from external film, macropore, and micropore diffusion resistances to mass transfer were determined, and the micropore diffusion resistance was found to be the major contributor. The micropore diffusivity as a function of crystal radius (Dc/rc 2) was determined and found to change between 5.72 × 10-4 and 1.34 × 10-2 s-1 in the temperature range studied.Article Citation - WoS: 81Citation - Scopus: 102Effects of Equivalence Ratio on Species and Soot Concentrations in Premixed N-Heptane Flames(Elsevier Ltd., 2002) İnal, Fikret; Senkan, Selim M.The micro-structure of laminar premixed, atmospheric-pressure, fuel-rich flames of n-heptane/oxygen/argon has been studied at two equivalence ratios (C/O = 0.63 and C/O = 0.67). A heated quartz microprobe coupled to an online gas chromatography/mass spectrometry (HP 5890 Series II/HP 5972) has been used to establish the identities and absolute concentrations of stable major, minor, and trace species by the direct analysis of samples withdrawn from the flames. Benzene was the most abundant aromatic compound identified. The largest PAH detected were the family of C18H10 (molecular weight of 226) that include cyclopenta[cd]pyrene and benzo[ghi]fluoranthene, with peak concentrations reaching 8 ppm and 6 ppm, respectively. Soot particle diameters, number densities, and volume fractions were determined using classical light scattering and extinction measurements. The largest soot particle diameter measured was about 18 nm and the soot volume fraction reached the amount of 4.9 × 10-7.Article Citation - WoS: 17Citation - Scopus: 18Solvent Diffusion in Amorphous Polymers: Polystyrene-Solvent Systems(John Wiley and Sons Inc., 2000) Tıhmınlıoğlu, Funda; Danner, Ronald P.The inverse gas chromatography (IGC) technique was used to obtain the partition and diffusion coefficients of solvents in polystyrene over a wide range of temperatures. Infinite dilution experiments were performed with three solvents: toluene, benzene, and hexane. Finite concentration data were measured for the polystyrene-toluene system at various concentrations from 110 to 180 °C. For the finite concentration region, the modified capillary column model used by Tihminlioglu and Danner (J Chromatogr A 1999, 845, 93-101) was used to calculate diffusion and thermodynamic data. Finite concentration thermodynamic data were also calculated with the retention theory approach and compared with the capillary column model. The experimental IGC results are in good agreement with data from other experimental techniques.Article Citation - WoS: 19Citation - Scopus: 20Solvent Diffusion in Amorphous Polymers: Polyvinyl Acetate-Toluene System(John Wiley and Sons Inc., 2000) Tıhmınlıoğlu, Funda; Danner, Ronald P.; Lützow, Norbert; Duda, John LarryIn a previous publication (Tihminlioglu et al., J Polym Sci Part B: Polym Phys 1997, 35, 1279), we presented an extensive analysis of the polyvinyl acetate-toluene system. The inverse gas chromatography (IGC) technique was used to measure phase equilibria and diffusion coefficients above and near the glass-transition temperature of a polymer. At temperatures above the glass transition, the capillary column model developed by Pawlisch et al. (Macromolecules 1987, 20, 1564) was used. For the finite concentration region, the modified model of Tihminlioglu and Danner (J Chromatogr A 1999, 845, 93) was applied. Data obtained with the IGC method were in agreement with data measured with the gravimetric and piezoelectric sorption techniques. In this work, we revisit the partition coefficient issue and provide some new data at lower temperatures. At temperatures near the glass-transition temperature, the modification of the capillary column model proposed by Vrentas et al. (Macromolecules 1993, 26, 6670) was used for the infinite dilution region. The diffusion data correlated well with the Vrentas-Duda free-volume model.