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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.


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.


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.


Ozyon S.,Dumlupinar University | Aydin D.,Dumlupinar University
Energy Conversion and Management | Year: 2013

In this study, prohibited operating zone economic power dispatch problem which considers ramp rate limit, has been solved by incremental artificial bee colony algorithm (IABC) and incremental artificial bee colony algorithm with local search (IABC-LS) methods. The transmission line losses used in the solution of the problem have been computed by B-loss matrix. IABC, IABC-LS methods have been applied to three different test systems in literature which consist of 6, 15 and 40 generators. The attained optimum solution values have been compared with the optimum results in literature and have been discussed. © 2012 Elsevier Ltd. All rights reserved.


Ozzaim C.,Dumlupinar University
IEEE Antennas and Wireless Propagation Letters | Year: 2011

A coax-fed thin-wire monopole antenna loaded by an annular cylindrical dielectric ring resonator (DRR) containing a step in its outer radius is studied numerically. The results obtained with computations based on bodies of revolution (BoR) followed by the method of moments (MoM) procedure are compared to the results of commercially available software tools for verification. The new hybrid antenna can easily offer a fractional bandwidth up to 110% for the magnitude of the input reflection coefficient, |S11| < -10 dB. The |S11| response of the newly proposed antenna shows an additional resonance compared to its cylindrical ring counterpart without the step, resulting in at least 10% larger impedance bandwidth. © 2006 IEEE.


Kaya G.,Dumlupinar University
Ceramics International | Year: 2013

The objective of this study is to produce and characterize self-colored dental zirconia blocks by using zirconia raw material having Fe 2O 3 content. Five different compositions with different amounts of Fe 2O 3 were prepared by using two different raw materials. The shaped samples were sintered at 1500 °C for 2 h. Color differences, phase formations, microhardness, fracture toughness, and microstructures of the specimens were investigated. Self-colored zirconia blocks and frameworks of desired physical and mechanical properties for dental restorations can be produced by using zirconia raw material having Fe 2O 3 content. © 2012 Elsevier Ltd and Techna Group S.r.l.


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.


Recent technical developments have made it possible to generate electricity from geothermal resources with low and medium enthalpy. One of these technologies is the Kalina Cycle System (KCS-34). In this study, electricity generation from Simav geothermal field is investigated. The optimum operating conditions for the KCS-34 plant design are determined on the basis of the exergetic and life-cycle-cost concepts. With the best design, power generation of 41.2 MW and electricity production of 346.1 GWh/a can be obtained with an energetic efficiency of 14.9% and exergetic efficiency of 36.2%. It is shown that, with the currently prevailing interest and inflation rates, the plant designs considered are economically feasible for values of the present worth factor (PWF) higher than 6. © 2010 Elsevier Masson SAS. All rights reserved.


This study presents the preparation of LiMn2O4 spinel type ion-sieves, characterization of their Li+ extraction/insertion rates and discussion about the effect of the particle structure and morphology on lithium adsorption rate. LiMn2O4 spinel powders were synthesized by ultrasonic spray pyrolysis and solid state reaction. LiMn 2O4 powder prepared by pyrolysis has agglomerate structure and spherical shape with a very uniform morphology while the other has a needle like structure with sharp edges and rough surface. Besides this, the mean particle/agglomerate size and specific surface area of the powders were relatively the same. The Li+ uptake capacity of the sieve (delithiated lithium manganese powder) which has agglomerate structure was 34.9 mg/g for which the maximum adsorption capacity of the sieve was 38.67 mg/g theoretically. Besides, the sieve uptake was about 94 wt% of the maximum amount within 3 h while the other sieve required 24 h for the relatively equal uptake amount (32.8 mg/g). © 2010 Published by Elsevier B.V.

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