A novel voltammetric sensor based on gold nanoparticles involved in p-aminothiophenol functionalized multi-walled carbon nanotubes: Application to the simultaneous determination of quercetin and rutin
Yola M.L.,Sinop University |
Atar N.,Dumlupinar University
Electrochimica Acta | Year: 2014
Carbon nanotubes are expected to play a significant role in the design and manufacture of many nano-material devices in the future. Carbon nanotubes exhibit many unique properties which generate strong interests in studying their applications. In addition, certain properties of gold nanoparticles (e.g., conductivity, catalytic and photocatalytic activity) suggest that gold-nanoparticle-functionalized carbon nanotubes may prove applicable in future fabrication of nanodevices. In this study, gold nanoparticles (AuNPs) with the mean diameters of 20-25 nm were self-assembled onto the surfaces of p-aminothiophenol functionalized multi-walled carbon nanotubes (p-MWCNs) sheets. The p-MWCNs and AuNPs/p-MWCNs nanocomposites were characterized by reflection-absorption infrared spectroscopy (RAIRS), transmission electron microscope (TEM), x-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS) and x-ray diffraction (XRD) method. The simultaneous determination of quercetin (QR) and rutin (RT) was performed by square wave voltammetry (SWV) on glassy carbon electrode (GCE) modified with AuNPs/p-MWCNs nanocomposite (AuNPs/p-MWCNs-GCE). QR presented two oxidation steps at Ea1 of 270 mV and Ea2 of 450 mV and RT presented only one oxidation step at Ea of 360 mV at AuNPs/p-MWCNs-GCE. The linearity ranges and the detection limits of QR and RT were 1.0 × 10 -9 - 5.0 × 10-8 M and 3.3 × 10-10. The application of the prepared nanocomposite to the analysis of real sample was also investigated. © 2013 Elsevier Ltd.
Partal T.,Dumlupinar University
International Journal of Climatology | Year: 2012
This study focuses on the variability of precipitation and runoff over time and the relationship between precipitation and runoff at the Aegean region of Turkey. The wavelet transform technique, which has been widely used for the analysis of hydrological data in the last years, provides detailed information regarding time-frequency representation of the data. According to the continuous wavelet transform (CWT), the main periodic events are seen at the scale levels of 1-4 and 16 years. This study shows that variability of both the runoff and the precipitation over time is generally similar, with noticeable decrease in the runoff in all the stations. The dominant inter-decadal periodic events are seen approximately at the 16-year scale level. This periodicity is dominant between 1962 and 1985 for the runoff data. The power of the 16-year periodicity becomes less apparent after 1985. In addition, the global wavelet spectrum (GWS) and the decomposed series of the hydrological data were studied to investigate the effective periodic characteristic of the observed data. In this study, the period of investigation is 39 years extending from 1962 to 2000. The validity of the decreasing trend founded by previous studies for the Aegean hydrological data is verified by the wavelet analysis. © 2010 Royal Meteorological Society.
Parlak C.,Dumlupinar University
Journal of Molecular Structure | Year: 2010
FT-IR and Raman spectra together with the vibrational spectral assignments between 4000 and 400 cm-1 of 4-(1-Pyrrolidinyl)piperidine (4-pypp) have been reported. The optimized structural parameters (bond lengths, bond and dihedral angles), normal mode frequencies and corresponding vibrational assignments of 4-pypp (C9H18N2) have been theoretically examined by means of B3LYP density functional method with 6-31G(d) basis set. Infrared intensity and Raman activities have also been calculated and reported. Theoretical results have been successfully compared against obtained experimental data. © 2009 Elsevier B.V. All rights reserved.
Arslan O.,Dumlupinar University
Energy | Year: 2011
Recent technical developments have made it possible to generate electricity from geothermal resources of low and medium enthalpy. One of these technologies is the Kalina Cycle System. In this study, electricity generation from Simav geothermal field was investigated using the Kalina cycle system-34 (KCS-34). However, the design of these technologies requires more proficiency and longer times within complex calculations. An artificial neural network (ANN) is a new tool used to make a decision for the optimum working conditions of the processes within the expertise. In this study, the back-propagation learning algorithm with three different variants, namely Levenberg-Marguardt (LM), Pola-Ribiere Conjugate Gradient (CGP), and Scaled Conjugate Gradient (SCG), were used in the network so that the best approach could be found. The most suitable algorithm found was LM with 7 neurons in a single hidden layer. The obtained weights were used in optimization process by coupling the life-cycle-cost concepts. © 2011 Elsevier Ltd.
Akbulut A.,Dumlupinar University
Energy | Year: 2012
Conventional energy usage has various environmental effects that cause global warming. Renewable energy sources are, thus, more favorable, because they have nearly zero emission. Biogas was merely seen as a sub-product obtained from anaerobic decomposition (without oxygen) of organic residue. One of the key concerns of biogas plants with energy generation is the disposal of comparatively large amounts of digestate in an economically and environmentally sustainable manner. In this article, the economic performance of the given biogas plant has been analyzed based on net present value (NPV) and energetic pay-back time (EPBT) concepts. The case study has produced an electricity yield of 2,223,951 kWh per year of feedstock digested. The hourly producible electricity energy has been 277.99 kWh. The producible heat energy has been 2,566,098 kWh per year and 320.76 kWh per day, respectively. The produced solid fertilizer and liquid fertilizer, respectively, have been 2047 t/a and 26,055 t/a. The plant with dairy cows and stall is a good economic situation under 3.4 years pay-back time, earning profits and showing a positive NPV of €27.74 million. The co-generation system has reduced emissions by 7506 t CO 2 per year. © 2012 Elsevier Ltd.