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Aygar G.,Middle East Technical University | Kaya M.,Atilim University | Ozkan N.,Middle East Technical University | Kocabiyik S.,Middle East Technical University | And 2 more authors.
Journal of Physics and Chemistry of Solids | Year: 2015

Surface modified cobalt ferrite (CoFe2O4) nanoparticles containing Ni-NTA affinity group were synthesized and used for the separation of histidine tag proteins from the complex matrices through the use of imidazole side chains of histidine molecules. Firstly, CoFe2O4 nanoparticles with a narrow size distribution were prepared in an aqueous solution using the controlled co-precipitation method. In order to obtain small CoFe2O4 agglomerates, oleic acid and sodium chloride were used as dispersants. The CoFe2O4 particles were coated with silica and subsequently the surface of these silica coated particles (SiO2-CoFe2O4) was modified by amine (NH2) groups in order to add further functional groups on the silica shell. Then, carboxyl (-COOH) functional groups were added to the SiO2-CoFe2O4 magnetic nanoparticles through the NH2 groups. After that Nα,Nα-Bis(carboxymethyl)-l-lysine hydrate (NTA) was attached to carboxyl ends of the structure. Finally, the surface modified nanoparticles were labeled with nickel (Ni) (II) ions. Furthermore, the modified SiO2-CoFe2O4 magnetic nanoparticles were utilized as a new system that allows purification of the N-terminal His-tagged recombinant small heat shock protein, Tpv-sHSP 14.3. © 2015 Elsevier Ltd. Allrightsreserved.

Adiguzel Y.,Istanbul Kemerburgaz University | Kulah H.,Middle East Technical University | Kulah H.,Universiteler Mah
Biosensors and Bioelectronics | Year: 2015

The scope of the applications of breath sensors is abundant in disease diagnosis. Lung cancer diagnosis is a well-fitting health-related application of this technology, which is of utmost importance in the health sector, because lung cancer has the highest death rate among all cancer types, and it brings a high yearly global burden. The aim of this review is first to provide a rational basis for the development of breath sensors for lung cancer diagnostics from a historical perspective, which will facilitate the transfer of the idea into the rapidly evolving sensors field. Following examples with diagnostic applications include colorimetric, composite, carbon nanotube, gold nanoparticle-based, and surface acoustic wave sensor arrays. These select sensor applications are widened by the state-of-the-art developments in the sensors field. Coping with sampling sourced artifacts and cancer staging are among the debated topics, along with the other concerns like proteomics approaches and biomimetic media utilization, feature selection for data classification, and commercialization. © 2014 Elsevier B.V.

Akdeniz Y.,Nigde University | Timurkutluk B.,Nigde University | Timurkutluk C.,Nigde University | Timurkutluk C.,Universiteler Mah
International Journal of Hydrogen Energy | Year: 2016

In addition to pure hydrogen, solid oxide fuel cells (SOFCs) can utilize hydrocarbons as a fuel. However, conventional Ni-based anodes exhibit an excellent catalytic activity towards the hydrocarbon cracking reaction and thus the carbon deposition occurs in the anode. The deposited carbons quickly deactivate the anode irreversibly by covering the active surface of the anode catalyst. As a result, a significant degradation in the cell performance can be seen. In this study, the anode structure is modified by the addition of copper (Cu) and ceria (CeO2) to increase the coking resistance of the cell under direct methane fuel. In this respect, the anodes are infiltrated by different amounts of Cu and CeO2 nitrates via the wet impregnation technique to investigate the effects of Cu and CeO2 loadings on the carbon tolerance of the cell. The effects of the anode porosity and composition are also considered in the study. The carbon resistance thus the service life of the cell with Cu/CeO2/Ni/YSZ anodes is found to be significantly higher than that of conventional Ni-based anodes under direct dry methane fuel. © 2016 Hydrogen Energy Publications LLC

Korkmaz H.,Nigde University | Timurkutluk B.,Nigde University | Timurkutluk C.,Nigde University | Timurkutluk C.,Universiteler Mah
International Journal of Hydrogen Energy | Year: 2016

The microstructure has a great impact on the performance of solid oxide fuel/electrolyzer cells while the cell fabrication parameters mainly determine the microstructure of the cell components. In this study, a number of five-layered cells with 16 cm2 active area are fabricated and the effects of several cell fabrication parameters including sintering temperature and electrode composition on the hydrogen production performance are investigated. The experimental results showed that the optimum sintering temperature of the electrolyte, cathode and anode should be 1400 °C, 1250 °C and 1075 °C, respectively, while the solid weight ratio of both NiO-ScSZ cathode and LSM-ScSZ anode functional layer should be 1:1. The optimized cell produces 38 Sccm H2 at an operation temperature of 800 °C and 1.5 V. Then, the cell size is increased to a commercial size of 81 cm2 active area. The final cell exhibits an acceptable H2 production of 154 Sccm H2 at 800 °C and 1.5 V. The relatively lower performance of the commercial-size cell is attributed to the inadequate current distribution/collection due to the increased surface area. © 2016 Hydrogen Energy Publications LLC

Mat A.,Recep Tayyip Erdogan University | Timurkutluk B.,Nigde University | Timurkutluk C.,Nigde University | Timurkutluk C.,Universiteler Mah | Kaplan Y.,Nigde University
Ceramics International | Year: 2014

Various commercially available anode and cathode materials are investigated as the anode and cathode contact paste, respectively, for solid oxide fuel cells. In order to obtain a printable paste, chosen materials are mixed with an organic vehicle and a thinner as well as a pore former. The effect of the contact materials on the cell performance is evaluated experimentally via cell performance measurements by installing a short stack. The pastes are brush painted on the corresponding interconnector and current collecting mesh. A short stack without any contact paste is also tested for comparison as a base case. The impedance and microstructural analyses are also performed through an impedance analyzer and a scanning electron microscope, respectively. The effects of solid loading for two anode and two cathode contact paste materials which provide the best two performances during the electrochemical performance tests are also studied. After optimizing the solid loading in the anode and cathode contact paste according to the performance results, the best contact materials for each side are decided. The final short stack is then installed by using the best combination of contact pastes and then tested. The final cell shows 0.39 W cm-2 and 0.90 W cm-2 peak power densities at 700 °C and 800 °C, respectively, whereas the base cell provides only 0.26 W cm -2 peak power density at 800 °C. The improvement in the cell performance is considered to be due to the enhanced contact and better current collecting by employing contact pastes. © 2014 Elsevier Ltd and Techna Group S.r.l.

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