Materials Science and Engineering
2018 |
İncel, Anıl; Demir, Mustafa M Triboluminescent composite microspheres consisting of alginate and EuD4TEA crystals Journal Article Sensors and Actuators A: Physical, 269 , pp. 556 - 562, 2018, ISSN: 0924-4247. @article{incel2018556, title = {Triboluminescent composite microspheres consisting of alginate and EuD4TEA crystals}, author = {Anıl İncel and Mustafa M Demir}, url = {http://www.sciencedirect.com/science/article/pii/S0924424717317727}, doi = {https://doi.org/10.1016/j.sna.2017.12.023}, issn = {0924-4247}, year = {2018}, date = {2018-01-01}, journal = {Sensors and Actuators A: Physical}, volume = {269}, pages = {556 - 562}, abstract = {Alginate is utilized to obtain luminescent composite microspheres containing europium tetrakis (dibenzoylmethide) triethylammonium (EuD4TEA) triboluminescent (TL) crystals. Na alginate is initially treated with Ca(II) and then Eu (III) so that physically-crosslinked alginate microspheres were obtained. EuD4TEA crystals are precipitated in situ on the surface of the spheres upon treatment with dibenzoylmethane (DBM) and triethylamine (TEA). The EuD4TEA/alginate composite spheres are swollen in aqueous system, the diameter of the microspheres increases from 180 up to 405 μm in 48 h. TL intensity of the spheres swollen in 1 h decreases 4 folds compared to dry spheres; however, it systematically increases as the swelling time is extended step-wise to 48 h. Swelling may develop structural homogenity in the microsphere that supresses the optical scattering and may lead to better transmittance of the TL signal.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Alginate is utilized to obtain luminescent composite microspheres containing europium tetrakis (dibenzoylmethide) triethylammonium (EuD4TEA) triboluminescent (TL) crystals. Na alginate is initially treated with Ca(II) and then Eu (III) so that physically-crosslinked alginate microspheres were obtained. EuD4TEA crystals are precipitated in situ on the surface of the spheres upon treatment with dibenzoylmethane (DBM) and triethylamine (TEA). The EuD4TEA/alginate composite spheres are swollen in aqueous system, the diameter of the microspheres increases from 180 up to 405 μm in 48 h. TL intensity of the spheres swollen in 1 h decreases 4 folds compared to dry spheres; however, it systematically increases as the swelling time is extended step-wise to 48 h. Swelling may develop structural homogenity in the microsphere that supresses the optical scattering and may lead to better transmittance of the TL signal. |
Sevim, Koray; Sevinçli, Hâldun Tuning thermal transport in graphene via combinations of molecular antiresonances Journal Article Carbon, 140 , pp. 603 - 609, 2018, ISSN: 0008-6223. @article{sevim2018603, title = {Tuning thermal transport in graphene via combinations of molecular antiresonances}, author = {Koray Sevim and Hâldun Sevinçli}, url = {http://www.sciencedirect.com/science/article/pii/S000862231830784X}, doi = {https://doi.org/10.1016/j.carbon.2018.08.050}, issn = {0008-6223}, year = {2018}, date = {2018-01-01}, journal = {Carbon}, volume = {140}, pages = {603 - 609}, abstract = {We propose a method to engineer the phonon thermal transport properties of low dimensional systems. The method relies on introducing a predetermined combination of molecular adsorbates, which give rise to antiresonances at frequencies specific to the molecular species. Despite their dissimilar transmission spectra, thermal resistances due to individual molecules remain almost the same for all species. On the other hand, thermal resistance due to combinations of different species are not additive and show large differences depending on the species. Using a toy model, the physics underlying the violation of resistance summation rule is investigated. It is demonstrated that equivalent resistance of two scatterers having the same resistances can be close to the sum of the constituents or ∼ 70% of it depending on the relative positions of the antiresonances. The relative positions of the antiresonances determine the net change in transmission, therefore the equivalent resistance. Since the entire spectrum is involved in phonon spectrum changes in different parts of the spectrum become important. Performing extensive first-principles based computations, we show that these distinctive attributes of phonon transport can be useful to tailor the thermal transport through low dimensional materials, especially for thermoelectric and thermal management applications.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We propose a method to engineer the phonon thermal transport properties of low dimensional systems. The method relies on introducing a predetermined combination of molecular adsorbates, which give rise to antiresonances at frequencies specific to the molecular species. Despite their dissimilar transmission spectra, thermal resistances due to individual molecules remain almost the same for all species. On the other hand, thermal resistance due to combinations of different species are not additive and show large differences depending on the species. Using a toy model, the physics underlying the violation of resistance summation rule is investigated. It is demonstrated that equivalent resistance of two scatterers having the same resistances can be close to the sum of the constituents or ∼ 70% of it depending on the relative positions of the antiresonances. The relative positions of the antiresonances determine the net change in transmission, therefore the equivalent resistance. Since the entire spectrum is involved in phonon spectrum changes in different parts of the spectrum become important. Performing extensive first-principles based computations, we show that these distinctive attributes of phonon transport can be useful to tailor the thermal transport through low dimensional materials, especially for thermoelectric and thermal management applications. |
Zeydanli, Damla; Akman, Suleyman; Vakifahmetoglu, Cekdar Polymer-derived ceramic adsorbent for pollutant removal from water Journal Article Journal of the American Ceramic Society, 101 (6), pp. 2258-2265, 2018. @article{doi:10.1111/jace.15423, title = {Polymer-derived ceramic adsorbent for pollutant removal from water}, author = {Damla Zeydanli and Suleyman Akman and Cekdar Vakifahmetoglu}, url = {https://ceramics.onlinelibrary.wiley.com/doi/abs/10.1111/jace.15423}, doi = {10.1111/jace.15423}, year = {2018}, date = {2018-01-01}, journal = {Journal of the American Ceramic Society}, volume = {101}, number = {6}, pages = {2258-2265}, abstract = {Abstract Polymer-derived ceramic components (SiOC, sample W) were produced from preceramic polymer mixture and a catalyst. After curing and pyrolysis, some of the samples etched by hydrofluoric acid to obtain carbonaceous SiOC (C-rich SiOC, sample W-HF). W and W-HF were tested as an adsorbent material to remove both heavy-metal ions (Cr (III), Pb (III), and Cd (II)) and cationic dyes (Methylene Blue (MB), Rhodamine B (RB), and Crystal Violet (CV)) from aqueous solutions. HF-treated high surface area SiOC samples had quite high adsorption affinity for cationic dyes. According the Langmuir isotherm model the maximum dye uptake values were found to be around to 50 mg/g for sample W, whereas those for sample W-HF ranged from 104 to 186 mg/g. Regeneration studies were conducted both by heat treatment and leaching, high recovery yields (always above 97%) of MB adsorption were obtained.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Abstract Polymer-derived ceramic components (SiOC, sample W) were produced from preceramic polymer mixture and a catalyst. After curing and pyrolysis, some of the samples etched by hydrofluoric acid to obtain carbonaceous SiOC (C-rich SiOC, sample W-HF). W and W-HF were tested as an adsorbent material to remove both heavy-metal ions (Cr (III), Pb (III), and Cd (II)) and cationic dyes (Methylene Blue (MB), Rhodamine B (RB), and Crystal Violet (CV)) from aqueous solutions. HF-treated high surface area SiOC samples had quite high adsorption affinity for cationic dyes. According the Langmuir isotherm model the maximum dye uptake values were found to be around to 50 mg/g for sample W, whereas those for sample W-HF ranged from 104 to 186 mg/g. Regeneration studies were conducted both by heat treatment and leaching, high recovery yields (always above 97%) of MB adsorption were obtained. |
Göksel, Yaman; i, İklima K; Akdogan, Yasar Spontaneous Adhesion of DOPA and Tryptophan Functionalized PEG to Polystyrene Nanobeads: An EPR Study Inproceedings Applied Electromagnetic Engineering for Advanced Materials from Macro-to Nanoscale under Static-to Shock Loading, pp. 243–247, Trans Tech Publications, 2018. @inproceedings{goksel2018, title = {Spontaneous Adhesion of DOPA and Tryptophan Functionalized PEG to Polystyrene Nanobeads: An EPR Study}, author = {Yaman Göksel and İklima K i and Yasar Akdogan}, doi = {10.4028/www.scientific.net/MSF.915.243}, year = {2018}, date = {2018-01-01}, booktitle = {Applied Electromagnetic Engineering for Advanced Materials from Macro-to Nanoscale under Static-to Shock Loading}, volume = {915}, pages = {243--247}, publisher = {Trans Tech Publications}, series = {Materials Science Forum}, abstract = {Wet adhesion is achieved by mussels so naturally. Their adhesion mechanism has inspired scientists to obtain wet adhesives for a long time. The amino acid 3,4-dihydroxyphenylalanine (DOPA) produced by mussels adheres to different types of surfaces and also contributes to cohesive interactions. Here, we showed the spontaneous adhesion of DOPA functionalized four armed poly (ethylene glycol) (PEG) polymer to spin labeled polystyrene (SL-PS) nanosurfaces by electron paramagnetic resonance (EPR) spectroscopy. In addition to DOPA, adhesion property of another amino acid of tryptophan (Trp) was studied. Trp attached four armed PEG polymers did not adhere to the surface of SL-PS in the force free condition. However, two armed DOPA and two armed Trp functionalized PEG adhere to the PS.}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } Wet adhesion is achieved by mussels so naturally. Their adhesion mechanism has inspired scientists to obtain wet adhesives for a long time. The amino acid 3,4-dihydroxyphenylalanine (DOPA) produced by mussels adheres to different types of surfaces and also contributes to cohesive interactions. Here, we showed the spontaneous adhesion of DOPA functionalized four armed poly (ethylene glycol) (PEG) polymer to spin labeled polystyrene (SL-PS) nanosurfaces by electron paramagnetic resonance (EPR) spectroscopy. In addition to DOPA, adhesion property of another amino acid of tryptophan (Trp) was studied. Trp attached four armed PEG polymers did not adhere to the surface of SL-PS in the force free condition. However, two armed DOPA and two armed Trp functionalized PEG adhere to the PS. |
Badalov, S V; Kandemir, A; Sahin, H Monolayer AsTe2: Stable Robust Metal in 2D, 1D and 0D Journal Article ChemPhysChem, 19 (17), pp. 2176-2182, 2018. @article{doi:10.1002/cphc.201800473, title = {Monolayer AsTe2: Stable Robust Metal in 2D, 1D and 0D}, author = {S V Badalov and A Kandemir and H Sahin}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/cphc.201800473}, doi = {10.1002/cphc.201800473}, year = {2018}, date = {2018-01-01}, journal = {ChemPhysChem}, volume = {19}, number = {17}, pages = {2176-2182}, abstract = {Abstract The structural, phononic, and electronic properties of the monolayer structures of AsTe2 are characterized by performing density functional theory (DFT) calculations. Total energy optimization and phonon calculations reveal that single layers of the 2H-AsTe2 and 1T-AsTe2 phases form dynamically stable crystal structures. Electronic structure analysis also shows that both 2H and 1T phases have nonmagnetic metallic character. It is also predicted that the metallic nature of the ultra-thin both 2H-AsTe2 and 1T-AsTe2 structures remain unchanged even under high biaxial strain values. For further examination of the dimensionality effect in the robust metallicity in 2D AsTe2 phases, electronic characteristics of 1D nanoribbons and 0D quantum dots are also investigated. It is found that independent from the dimension and crystallographic orientations 0D and 1D structures of 2H- and 1T-AsTe2 structures have metallic behavior. It is found that single layers of AsTe2 are quite promising materials for nanodevice applications owing to the robust metallic character.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Abstract The structural, phononic, and electronic properties of the monolayer structures of AsTe2 are characterized by performing density functional theory (DFT) calculations. Total energy optimization and phonon calculations reveal that single layers of the 2H-AsTe2 and 1T-AsTe2 phases form dynamically stable crystal structures. Electronic structure analysis also shows that both 2H and 1T phases have nonmagnetic metallic character. It is also predicted that the metallic nature of the ultra-thin both 2H-AsTe2 and 1T-AsTe2 structures remain unchanged even under high biaxial strain values. For further examination of the dimensionality effect in the robust metallicity in 2D AsTe2 phases, electronic characteristics of 1D nanoribbons and 0D quantum dots are also investigated. It is found that independent from the dimension and crystallographic orientations 0D and 1D structures of 2H- and 1T-AsTe2 structures have metallic behavior. It is found that single layers of AsTe2 are quite promising materials for nanodevice applications owing to the robust metallic character. |
Kandemir, A; Peeters, F M; Sahin, H Monitoring the effect of asymmetrical vertical strain on Janus single layers of MoSSe via vibrational spectrum Journal Article The Journal of Chemical Physics, 149 (8), pp. 084707, 2018. @article{doi:10.1063/1.5043207, title = {Monitoring the effect of asymmetrical vertical strain on Janus single layers of MoSSe via vibrational spectrum}, author = {A Kandemir and F M Peeters and H Sahin}, url = {https://doi.org/10.1063/1.5043207}, doi = {10.1063/1.5043207}, year = {2018}, date = {2018-01-01}, journal = {The Journal of Chemical Physics}, volume = {149}, number = {8}, pages = {084707}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Sotthewes, Kai; Kap, Özlem; Wu, Hairong; Thompson, Damien; Huskens, Jurriaan; Zandvliet, Harold J W Ordering of Air-Oxidized Decanethiols on Au(111) Journal Article The Journal of Physical Chemistry C, 122 (15), pp. 8430-8436, 2018. @article{ozlemkap2018, title = {Ordering of Air-Oxidized Decanethiols on Au(111)}, author = {Kai Sotthewes and Özlem Kap and Hairong Wu and Damien Thompson and Jurriaan Huskens and Harold J W Zandvliet}, url = {https://doi.org/10.1021/acs.jpcc.8b01389}, doi = {10.1021/acs.jpcc.8b01389}, year = {2018}, date = {2018-01-01}, journal = {The Journal of Physical Chemistry C}, volume = {122}, number = {15}, pages = {8430-8436}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Mobaraki, Arash; Kandemir, Ali; Yapicioglu, Haluk; Gülseren, Oğuz; Sevik, Cem Validation of inter-atomic potential for WS2 and WSe2 crystals through assessment of thermal transport properties Journal Article Computational Materials Science, 144 , pp. 92 - 98, 2018, ISSN: 0927-0256. @article{mobaraki201892, title = {Validation of inter-atomic potential for WS2 and WSe2 crystals through assessment of thermal transport properties}, author = {Arash Mobaraki and Ali Kandemir and Haluk Yapicioglu and Oğuz Gülseren and Cem Sevik}, url = {http://www.sciencedirect.com/science/article/pii/S0927025617306900}, doi = {https://doi.org/10.1016/j.commatsci.2017.12.005}, issn = {0927-0256}, year = {2018}, date = {2018-01-01}, journal = {Computational Materials Science}, volume = {144}, pages = {92 - 98}, abstract = {In recent years, transition metal dichalcogenides (TMDs) displaying astonishing properties are emerged as a new class of two-dimensional layered materials. The understanding and characterization of thermal transport in these materials are crucial for efficient engineering of 2D TMD materials for applications such as thermoelectric devices or overcoming general overheating issues. In this work, we obtain accurate Stillinger-Weber type empirical potential parameter sets for single-layer WS2 and WSe2 crystals by utilizing particle swarm optimization, a stochastic search algorithm. For both systems, our results are quite consistent with first-principles calculations in terms of bond distances, lattice parameters, elastic constants and vibrational properties. Using the generated potentials, we investigate the effect of temperature on phonon energies and phonon linewidth by employing spectral energy density analysis. We compare the calculated frequency shift with respect to temperature with corresponding experimental data, clearly demonstrating the accuracy of the generated inter-atomic potentials in this study. Also, we evaluate the lattice thermal conductivities of these materials by means of classical molecular dynamics simulations. The predicted thermal properties are in very good agreement with the ones calculated from first-principles.}, keywords = {}, pubstate = {published}, tppubtype = {article} } In recent years, transition metal dichalcogenides (TMDs) displaying astonishing properties are emerged as a new class of two-dimensional layered materials. The understanding and characterization of thermal transport in these materials are crucial for efficient engineering of 2D TMD materials for applications such as thermoelectric devices or overcoming general overheating issues. In this work, we obtain accurate Stillinger-Weber type empirical potential parameter sets for single-layer WS2 and WSe2 crystals by utilizing particle swarm optimization, a stochastic search algorithm. For both systems, our results are quite consistent with first-principles calculations in terms of bond distances, lattice parameters, elastic constants and vibrational properties. Using the generated potentials, we investigate the effect of temperature on phonon energies and phonon linewidth by employing spectral energy density analysis. We compare the calculated frequency shift with respect to temperature with corresponding experimental data, clearly demonstrating the accuracy of the generated inter-atomic potentials in this study. Also, we evaluate the lattice thermal conductivities of these materials by means of classical molecular dynamics simulations. The predicted thermal properties are in very good agreement with the ones calculated from first-principles. |
Kalkan, S B; Aydın, H; Özkendir, D; Çelebi, C The effect of adsorbates on the electrical stability of graphene studied by transient photocurrent spectroscopy Journal Article Applied Physics Letters, 112 (1), pp. 013103, 2018. @article{doi:10.1063/1.5011454, title = {The effect of adsorbates on the electrical stability of graphene studied by transient photocurrent spectroscopy}, author = {S B Kalkan and H Aydın and D Özkendir and C Çelebi}, url = {https://doi.org/10.1063/1.5011454}, doi = {10.1063/1.5011454}, year = {2018}, date = {2018-01-01}, journal = {Applied Physics Letters}, volume = {112}, number = {1}, pages = {013103}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
2017 |
Iyikanat, F; Kandemir, A; Ozaydin, H D; Senger, R T; Sahin, H Hydrogenation-driven phase transition in single-layer TiSe2 Journal Article Nanotechnology, 28 (49), pp. 495709, 2017. @article{iyikanat2017, title = {Hydrogenation-driven phase transition in single-layer TiSe2}, author = {F Iyikanat and A Kandemir and H D Ozaydin and R T Senger and H Sahin}, url = {https://doi.org/10.1088%2F1361-6528%2Faa94ab}, doi = {10.1088/1361-6528/aa94ab}, year = {2017}, date = {2017-11-01}, journal = {Nanotechnology}, volume = {28}, number = {49}, pages = {495709}, publisher = {IOP Publishing}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Mayda, Selma; Kandemir, Zafer; Bulut, Nejat Electronic Structure of Cyanocobalamin: DFT+QMC Study Journal Article Journal of Superconductivity and Novel Magnetism, 30 (11), pp. 3301–3308, 2017, ISSN: 1557-1947. @article{mayda2017, title = {Electronic Structure of Cyanocobalamin: DFT+QMC Study}, author = {Selma Mayda and Zafer Kandemir and Nejat Bulut}, url = {https://doi.org/10.1007/s10948-016-3635-7}, doi = {10.1007/s10948-016-3635-7}, issn = {1557-1947}, year = {2017}, date = {2017-11-01}, journal = {Journal of Superconductivity and Novel Magnetism}, volume = {30}, number = {11}, pages = {3301--3308}, abstract = {We study the electronic structure and the magnetic correlations of cyanocobalamin (C63H88CoN14O14P) by using the framework of the multi-orbital single-impurity Haldane-Anderson model of a transition metal impurity in a semiconductor host. Here, we first determine the parameters of the Anderson Hamiltonian by performing density functional theory (DFT) calculations. Then, we use the quantum Monte Carlo (QMC) technique to obtain the electronic structure and the magnetic correlation functions for this effective model. We find that new electronic states, which correspond to impurity bound states, form above the lowest unoccupied level of the host semiconductor. These new states derive from the atomic orbitals at the cobalt site and the rest of the molecule. We observe that magnetic moments develop at the Co(3d$nu$) orbitals and over the surrounding sites. We also observe that antiferromagnetic correlations exist between the Co (3d$nu$) orbitals and the surrounding atoms. These antiferromagnetic correlations depend on the filling of the impurity bound states.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We study the electronic structure and the magnetic correlations of cyanocobalamin (C63H88CoN14O14P) by using the framework of the multi-orbital single-impurity Haldane-Anderson model of a transition metal impurity in a semiconductor host. Here, we first determine the parameters of the Anderson Hamiltonian by performing density functional theory (DFT) calculations. Then, we use the quantum Monte Carlo (QMC) technique to obtain the electronic structure and the magnetic correlation functions for this effective model. We find that new electronic states, which correspond to impurity bound states, form above the lowest unoccupied level of the host semiconductor. These new states derive from the atomic orbitals at the cobalt site and the rest of the molecule. We observe that magnetic moments develop at the Co(3d$nu$) orbitals and over the surrounding sites. We also observe that antiferromagnetic correlations exist between the Co (3d$nu$) orbitals and the surrounding atoms. These antiferromagnetic correlations depend on the filling of the impurity bound states. |
Akbali, B; Yanilmaz, A; Tomak, A; Tongay, S; Ç, C; Sahin, H Few-layer MoS2 as nitrogen protective barrier Journal Article Nanotechnology, 28 (41), pp. 415706, 2017. @article{akbali2017, title = {Few-layer MoS2 as nitrogen protective barrier}, author = {B Akbali and A Yanilmaz and A Tomak and S Tongay and C Ç and H Sahin}, url = {https://doi.org/10.1088%2F1361-6528%2Faa825e}, doi = {10.1088/1361-6528/aa825e}, year = {2017}, date = {2017-09-01}, journal = {Nanotechnology}, volume = {28}, number = {41}, pages = {415706}, publisher = {IOP Publishing}, abstract = {We report experimental and theoretical investigations of the observed barrier behavior of few-layer MoS2 against nitrogenation. Owing to its low-strength shearing, low friction coefficient, and high lubricity, MoS2 exhibits the demeanor of a natural N-resistant coating material. Raman spectroscopy is done to determine the coating capability of MoS2 on graphene. Surface morphology of our MoS2/graphene heterostructure is characterized by using optical microscopy, scanning electron microscopy, and atomic force microscopy. In addition, density functional theory-based calculations are performed to understand the energy barrier performance of MoS2 against nitrogenation. The penetration of nitrogen atoms through a defect-free MoS2 layer is prevented by a very high vertical diffusion barrier, indicating that MoS2 can serve as a protective layer for the nitrogenation of graphene. Our experimental and theoretical results show that MoS2 material can be used both as an efficient nanocoating material and as a nanoscale mask for selective nitrogenation of graphene layer.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We report experimental and theoretical investigations of the observed barrier behavior of few-layer MoS2 against nitrogenation. Owing to its low-strength shearing, low friction coefficient, and high lubricity, MoS2 exhibits the demeanor of a natural N-resistant coating material. Raman spectroscopy is done to determine the coating capability of MoS2 on graphene. Surface morphology of our MoS2/graphene heterostructure is characterized by using optical microscopy, scanning electron microscopy, and atomic force microscopy. In addition, density functional theory-based calculations are performed to understand the energy barrier performance of MoS2 against nitrogenation. The penetration of nitrogen atoms through a defect-free MoS2 layer is prevented by a very high vertical diffusion barrier, indicating that MoS2 can serve as a protective layer for the nitrogenation of graphene. Our experimental and theoretical results show that MoS2 material can be used both as an efficient nanocoating material and as a nanoscale mask for selective nitrogenation of graphene layer. |
Eschmann, Neil A; Georgieva, Elka R; Ganguly, Pritam; Borbat, Peter P; Rappaport, Maxime D; Akdogan, Yasar; Freed, Jack H; Shea, Joan-Emma; Han, Songi Signature of an aggregation-prone conformation of tau Journal Article Scientific Reports, 7 , pp. 44739 EP -, 2017, (Article). @article{eschmann2017, title = {Signature of an aggregation-prone conformation of tau}, author = {Neil A Eschmann and Elka R Georgieva and Pritam Ganguly and Peter P Borbat and Maxime D Rappaport and Yasar Akdogan and Jack H Freed and Joan-Emma Shea and Songi Han}, url = {https://doi.org/10.1038/srep44739}, year = {2017}, date = {2017-03-17}, journal = {Scientific Reports}, volume = {7}, pages = {44739 EP -}, publisher = {The Author(s) SN -}, note = {Article}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Gökçe, Melis; Şentürk, Ufuk; Uslu, Deniz K; Burgaz, Gözde; Şahin, Yüksel; Gökçe, Aytaç Gürhan Investigation of europium concentration dependence on the luminescent properties of borogermanate glasses Journal Article Journal of Luminescence, 192 , pp. 263 - 268, 2017, ISSN: 0022-2313. @article{gokce2017263, title = {Investigation of europium concentration dependence on the luminescent properties of borogermanate glasses}, author = {Melis Gökçe and Ufuk Şentürk and Deniz K Uslu and Gözde Burgaz and Yüksel Şahin and Aytaç Gürhan Gökçe}, url = {http://www.sciencedirect.com/science/article/pii/S0022231317306257}, doi = {https://doi.org/10.1016/j.jlumin.2017.06.041}, issn = {0022-2313}, year = {2017}, date = {2017-01-01}, journal = {Journal of Luminescence}, volume = {192}, pages = {263 - 268}, abstract = {In order to elucidate the effect of europium content on the optical and luminescent properties of borogermanate glasses, a series of Eu3+ doped 30B2O3-40GeO2-(30-x)Gd2O3 glasses with various doping levels (x=1–9mol%) have been synthesized and studied with transmission, absorption, photoluminescence and decay time measurements. The transmission spectra proved that the title glasses maintained a high transparency about 80% in the 440 to 900nm region. Based on the absorption spectra, the optical band gaps obtained from Tauc's plot can be narrowed by increasing content of Eu3+. From the photoluminescence spectra, the strongest red emission has been observed from the 5D0→7F2 level of Eu3+ ions in borogermanate glasses. The strongest emission and excitation intensities of Eu3+ ions are at the doping level of x=7 mol% and then these intensities decrease due to concentration quenching. The red to orange ratio (R/O) of 5D0→7F2 to 5D0→7F1 transitions has been investigated to predict the local environment of Eu3+ ions. Judd-Ofelt (J-O) analyses have been performed from the emission spectra. The values of R/O and Ω2 present an increase with increasing doping level, indicating the lower symmetric environment for Eu3+ ions and higher covalency for Eu-O bond. The emission efficiency calculated from J-O theory is 75% at x=2mol%. The decay time curves of 6P7/2→8S7/2 transition of Gd3+ ions and 5D0–7F2 transition of Eu3+ ions confirm the energy transfer from Gd3+ to Eu3+ ions.}, keywords = {}, pubstate = {published}, tppubtype = {article} } In order to elucidate the effect of europium content on the optical and luminescent properties of borogermanate glasses, a series of Eu3+ doped 30B2O3-40GeO2-(30-x)Gd2O3 glasses with various doping levels (x=1–9mol%) have been synthesized and studied with transmission, absorption, photoluminescence and decay time measurements. The transmission spectra proved that the title glasses maintained a high transparency about 80% in the 440 to 900nm region. Based on the absorption spectra, the optical band gaps obtained from Tauc's plot can be narrowed by increasing content of Eu3+. From the photoluminescence spectra, the strongest red emission has been observed from the 5D0→7F2 level of Eu3+ ions in borogermanate glasses. The strongest emission and excitation intensities of Eu3+ ions are at the doping level of x=7 mol% and then these intensities decrease due to concentration quenching. The red to orange ratio (R/O) of 5D0→7F2 to 5D0→7F1 transitions has been investigated to predict the local environment of Eu3+ ions. Judd-Ofelt (J-O) analyses have been performed from the emission spectra. The values of R/O and Ω2 present an increase with increasing doping level, indicating the lower symmetric environment for Eu3+ ions and higher covalency for Eu-O bond. The emission efficiency calculated from J-O theory is 75% at x=2mol%. The decay time curves of 6P7/2→8S7/2 transition of Gd3+ ions and 5D0–7F2 transition of Eu3+ ions confirm the energy transfer from Gd3+ to Eu3+ ions. |
Ozer, Imran; Tomak, Aysel; Zareie, Hadi M; Baran, Yusuf; Bulmus, Volga Effect of Molecular Architecture on Cell Interactions and Stealth Properties of PEG Journal Article Biomacromolecules, 18 (9), pp. 2699-2710, 2017, (PMID: 28777555). @article{doi:10.1021/acs.biomac.7b00443, title = {Effect of Molecular Architecture on Cell Interactions and Stealth Properties of PEG}, author = {Imran Ozer and Aysel Tomak and Hadi M Zareie and Yusuf Baran and Volga Bulmus}, url = {https://doi.org/10.1021/acs.biomac.7b00443}, doi = {10.1021/acs.biomac.7b00443}, year = {2017}, date = {2017-01-01}, journal = {Biomacromolecules}, volume = {18}, number = {9}, pages = {2699-2710}, note = {PMID: 28777555}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Çelik, Aslı; Topçu, Gökhan; Baba, Alper; Akdogan, Yasar; Şentürk, Ufuk; Demir, Mustafa M Experimental modeling of silicate-based geothermal deposits Journal Article Geothermics, 69 , pp. 65 - 73, 2017, ISSN: 0375-6505. @article{celik201765, title = {Experimental modeling of silicate-based geothermal deposits}, author = {Aslı Çelik and Gökhan Topçu and Alper Baba and Yasar Akdogan and Ufuk Şentürk and Mustafa M Demir}, url = {http://www.sciencedirect.com/science/article/pii/S0375650517300512}, doi = {https://doi.org/10.1016/j.geothermics.2017.04.007}, issn = {0375-6505}, year = {2017}, date = {2017-01-01}, journal = {Geothermics}, volume = {69}, pages = {65 - 73}, abstract = {Scaling by metal silicates represents a major obstacle for geothermal systems. A composition that enables the fabrication of artificial deposits is necessary for the rapid testing of potential inhibitors. In this work, artificial deposits were synthesized by employing experimental conditions similar to those in the Tuzla Geothermal Field in Turkey. Although refluxing enabled the formation of a precipitate that was similar to naturally formed deposits in color and texture, their elemental composition and morphology showed a mismatch. An autoclave enabled the production of a precipitate that more closely resembled naturally formed deposits in color, texture, elemental composition, and structure.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Scaling by metal silicates represents a major obstacle for geothermal systems. A composition that enables the fabrication of artificial deposits is necessary for the rapid testing of potential inhibitors. In this work, artificial deposits were synthesized by employing experimental conditions similar to those in the Tuzla Geothermal Field in Turkey. Although refluxing enabled the formation of a precipitate that was similar to naturally formed deposits in color and texture, their elemental composition and morphology showed a mismatch. An autoclave enabled the production of a precipitate that more closely resembled naturally formed deposits in color, texture, elemental composition, and structure. |
Isık, Tuğba; Demir, Mustafa M; Aydogan, Cansu; Ciftci, Mustafa; Yagci, Yusuf Hydrophobic coatings from photochemically prepared hydrophilic polymethacrylates via electrospraying Journal Article Journal of Polymer Science Part A: Polymer Chemistry, 55 (8), pp. 1338-1344, 2017. @article{doi:10.1002/pola.28501, title = {Hydrophobic coatings from photochemically prepared hydrophilic polymethacrylates via electrospraying}, author = {Tuğba Isık and Mustafa M Demir and Cansu Aydogan and Mustafa Ciftci and Yusuf Yagci}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/pola.28501}, doi = {10.1002/pola.28501}, year = {2017}, date = {2017-01-01}, journal = {Journal of Polymer Science Part A: Polymer Chemistry}, volume = {55}, number = {8}, pages = {1338-1344}, abstract = {ABSTRACT Linear poly(hydroxyethyl methacrylate-co-methyl methacrylate) P(HEMA-co-MMA) and poly(dimehylaminoethyl methacrylate-co-methyl methacrylate) P(DMAEMA-co-MMA) and their corresponding hyperbranched copolymers were synthesized by conventional photoinitiated free radical polymerization and self-condensing vinyl polymerization (SCVP) using Type I and Type II photoinitiators, respectively. Then, the polymers were processed by electrospraying in N, N-dimethylformamide. The surface of the resulting electrospray coatings was examined by SEM, XPS, and WCA then compared with those prepared by drop casting. Regardless of the structural nature of the polymers, electrospraying allows the preparation of rough surface that shows more hydrophobic behavior. Electrospray coatings with linear and hyperbranched copolymers exhibited WCA as ∼150° and ∼130°, respectively, indicating that branching reduces the WCA. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 1338–1344}, keywords = {}, pubstate = {published}, tppubtype = {article} } ABSTRACT Linear poly(hydroxyethyl methacrylate-co-methyl methacrylate) P(HEMA-co-MMA) and poly(dimehylaminoethyl methacrylate-co-methyl methacrylate) P(DMAEMA-co-MMA) and their corresponding hyperbranched copolymers were synthesized by conventional photoinitiated free radical polymerization and self-condensing vinyl polymerization (SCVP) using Type I and Type II photoinitiators, respectively. Then, the polymers were processed by electrospraying in N, N-dimethylformamide. The surface of the resulting electrospray coatings was examined by SEM, XPS, and WCA then compared with those prepared by drop casting. Regardless of the structural nature of the polymers, electrospraying allows the preparation of rough surface that shows more hydrophobic behavior. Electrospray coatings with linear and hyperbranched copolymers exhibited WCA as ∼150° and ∼130°, respectively, indicating that branching reduces the WCA. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 1338–1344 |
Semerci, T; Demirhan, Y; Miyakawa, N; Wang, H B; Ozyuzer, L Fabrication of Bi2212 Single Crystal Bolometer for Detection of Terahertz Waves Inproceedings Pereira, Mauro F; Shulika, Oleksiy (Ed.): THz for CBRN and Explosives Detection and Diagnosis, pp. 75–83, Springer Netherlands, Dordrecht, 2017, ISBN: 978-94-024-1093-8. @inproceedings{semerci2017, title = {Fabrication of Bi2212 Single Crystal Bolometer for Detection of Terahertz Waves}, author = {T Semerci and Y Demirhan and N Miyakawa and H B Wang and L Ozyuzer}, editor = {Mauro F Pereira and Oleksiy Shulika}, url = {https://link.springer.com/chapter/10.1007/978-94-024-1093-8_11}, isbn = {978-94-024-1093-8}, year = {2017}, date = {2017-01-01}, booktitle = {THz for CBRN and Explosives Detection and Diagnosis}, pages = {75--83}, publisher = {Springer Netherlands}, address = {Dordrecht}, abstract = {Terahertz (THz) radiation is in powerful region of electromagnetic spectrum because of prosperous application areas yet deficiency still exists about sources and detectors in despite of improvements of the research field in this range. This gap can be filled by focusing on development of THz detectors. Therefore, bolometers were preferred through many detectors due to detection sensitivity above 1 THz. In this study, Bi2Sr2CaCu2O8+$delta$ (Bi2212) single crystals were used to fabricate THz bolometric detector. Bi2212 single crystals were transferred on sapphire substrate by cleavage process and e-beam lithography and ion beam etching were used to fabricate the microchip clean room facilities. Custom-designed cryogenic cryostat was used for a-b axis electrical and THz response measurements with liquid nitrogen cooled system. After electrical measurements, Bi2212 microchips detected the signals using Stefan-Boltzmann Lamp and response time were calculated. This study have shown with our experimental results that Bi2212 single crystals are potential candidates for THz bolometric detectors.}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } Terahertz (THz) radiation is in powerful region of electromagnetic spectrum because of prosperous application areas yet deficiency still exists about sources and detectors in despite of improvements of the research field in this range. This gap can be filled by focusing on development of THz detectors. Therefore, bolometers were preferred through many detectors due to detection sensitivity above 1 THz. In this study, Bi2Sr2CaCu2O8+$delta$ (Bi2212) single crystals were used to fabricate THz bolometric detector. Bi2212 single crystals were transferred on sapphire substrate by cleavage process and e-beam lithography and ion beam etching were used to fabricate the microchip clean room facilities. Custom-designed cryogenic cryostat was used for a-b axis electrical and THz response measurements with liquid nitrogen cooled system. After electrical measurements, Bi2212 microchips detected the signals using Stefan-Boltzmann Lamp and response time were calculated. This study have shown with our experimental results that Bi2212 single crystals are potential candidates for THz bolometric detectors. |
İncel, Anıl; Emirdag-Eanes, Mehtap; McMillen, Colin D; Demir, Mustafa M Integration of Triboluminescent EuD4TEA Crystals to Transparent Polymers: Impact Sensor Application Journal Article ACS Applied Materials & Interfaces, 9 (7), pp. 6488-6496, 2017, (PMID: 28125205). @article{doi:10.1021/acsami.6b16330b, title = {Integration of Triboluminescent EuD4TEA Crystals to Transparent Polymers: Impact Sensor Application}, author = {Anıl İncel and Mehtap Emirdag-Eanes and Colin D McMillen and Mustafa M Demir}, url = {https://doi.org/10.1021/acsami.6b16330}, doi = {10.1021/acsami.6b16330}, year = {2017}, date = {2017-01-01}, journal = {ACS Applied Materials & Interfaces}, volume = {9}, number = {7}, pages = {6488-6496}, note = {PMID: 28125205}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Olcer, Y A; Demirkurt, M; Demir, M M; Eroglu, A E Development of molecularly imprinted polymers (MIPs) as a solid phase extraction (SPE) sorbent for the determination of ibuprofen in water Journal Article RSC Adv., 7 , pp. 31441-31447, 2017. @article{C7RA05254Eb, title = {Development of molecularly imprinted polymers (MIPs) as a solid phase extraction (SPE) sorbent for the determination of ibuprofen in water}, author = {Y A Olcer and M Demirkurt and M M Demir and A E Eroglu}, url = {http://dx.doi.org/10.1039/C7RA05254E}, doi = {10.1039/C7RA05254E}, year = {2017}, date = {2017-01-01}, journal = {RSC Adv.}, volume = {7}, pages = {31441-31447}, publisher = {The Royal Society of Chemistry}, abstract = {Ibuprofen is a well-known endocrine disrupter. In this study, highly selective molecularly imprinted polymers (MIPs) with different morphologies were synthesized via precipitation and bulk polymerization of methacrylic acid (MAA) and trimethylolpropane trimethacrylate (TRIM) in the presence of ibuprofen as a template. Non-imprinted polymers (NIPs) were also synthesized via the same procedure in the absence of ibuprofen. Spherical and monolithic MIPs were obtained using different experimental conditions, and the spherical MIP was shown to have better sorption towards ibuprofen. The optimum sample pH, sorbent amount, sample volume, and sorption time were determined to be 8.0, 25.0 mg, 10.0 mL, and 30.0 min, respectively. A methanol water mixture (MeOH : H2O, 80 : 20, pH 3.0) was employed as an eluent with >97% (±0.8}, keywords = {}, pubstate = {published}, tppubtype = {article} } Ibuprofen is a well-known endocrine disrupter. In this study, highly selective molecularly imprinted polymers (MIPs) with different morphologies were synthesized via precipitation and bulk polymerization of methacrylic acid (MAA) and trimethylolpropane trimethacrylate (TRIM) in the presence of ibuprofen as a template. Non-imprinted polymers (NIPs) were also synthesized via the same procedure in the absence of ibuprofen. Spherical and monolithic MIPs were obtained using different experimental conditions, and the spherical MIP was shown to have better sorption towards ibuprofen. The optimum sample pH, sorbent amount, sample volume, and sorption time were determined to be 8.0, 25.0 mg, 10.0 mL, and 30.0 min, respectively. A methanol water mixture (MeOH : H2O, 80 : 20, pH 3.0) was employed as an eluent with >97% (±0.8 |
İncel, Anıl; Reddy, Subrayal M; Demir, Mustafa M A new method to extend the stress response of triboluminescent crystals by using hydrogels Journal Article Materials Letters, 186 , pp. 210 - 213, 2017, ISSN: 0167-577X. @article{incel2017210, title = {A new method to extend the stress response of triboluminescent crystals by using hydrogels}, author = {Anıl İncel and Subrayal M Reddy and Mustafa M Demir}, url = {http://www.sciencedirect.com/science/article/pii/S0167577X16315944}, doi = {https://doi.org/10.1016/j.matlet.2016.10.007}, issn = {0167-577X}, year = {2017}, date = {2017-01-01}, journal = {Materials Letters}, volume = {186}, pages = {210 - 213}, abstract = {Polyacrylamide hydrogel entrapment of EuD4TEA or Cu(NCS)(py)2(PPh3) radically extends the emission time of the triboluminescent (TL) crystalline particles by a factor of 103, optimized when matching the hydrophilic/hydrophobic characteristics of the TL/gel components. Triboluminescence intensity improves with hydration of the TL/hydrogel composite. The composites may be used in impact-related sensor applications.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Polyacrylamide hydrogel entrapment of EuD4TEA or Cu(NCS)(py)2(PPh3) radically extends the emission time of the triboluminescent (TL) crystalline particles by a factor of 103, optimized when matching the hydrophilic/hydrophobic characteristics of the TL/gel components. Triboluminescence intensity improves with hydration of the TL/hydrogel composite. The composites may be used in impact-related sensor applications. |
Topçu, Gökhan; Çelik, Aslı; Baba, Alper; Demir, Mustafa M Design of Polymeric Antiscalants Based on Functional Vinyl Monomers for (Fe, Mg) Silicates Journal Article Energy & Fuels, 31 (8), pp. 8489-8496, 2017. @article{doi:10.1021/acs.energyfuels.7b01221, title = {Design of Polymeric Antiscalants Based on Functional Vinyl Monomers for (Fe, Mg) Silicates}, author = {Gökhan Topçu and Aslı Çelik and Alper Baba and Mustafa M Demir}, url = {https://doi.org/10.1021/acs.energyfuels.7b01221}, doi = {10.1021/acs.energyfuels.7b01221}, year = {2017}, date = {2017-01-01}, journal = {Energy & Fuels}, volume = {31}, number = {8}, pages = {8489-8496}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Sevinçli, Hâldun Nano Letters, 17 (4), pp. 2589-2595, 2017, (PMID: 28318269). @article{doi:10.1021/acs.nanolett.7b00366, title = {Quartic Dispersion, Strong Singularity, Magnetic Instability, and Unique Thermoelectric Properties in Two-Dimensional Hexagonal Lattices of Group-VA Elements}, author = {Hâldun Sevinçli}, url = {https://doi.org/10.1021/acs.nanolett.7b00366}, doi = {10.1021/acs.nanolett.7b00366}, year = {2017}, date = {2017-01-01}, journal = {Nano Letters}, volume = {17}, number = {4}, pages = {2589-2595}, note = {PMID: 28318269}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Güner, Tuğrul; Şentürk, Ufuk; Demir, Mustafa M Optical enhancement of phosphor-converted wLEDs using glass beads Journal Article Optical Materials, 72 , pp. 769 - 774, 2017, ISSN: 0925-3467. @article{guner2017769, title = {Optical enhancement of phosphor-converted wLEDs using glass beads}, author = {Tuğrul Güner and Ufuk Şentürk and Mustafa M Demir}, url = {http://www.sciencedirect.com/science/article/pii/S0925346717304810}, doi = {https://doi.org/10.1016/j.optmat.2017.07.033}, issn = {0925-3467}, year = {2017}, date = {2017-01-01}, journal = {Optical Materials}, volume = {72}, pages = {769 - 774}, abstract = {YAG:Ce3+ is a yellow-source compound commonly used in phosphor conversion layers for direct coating or remote phosphor configurations in LED illumination. This material, however, suffers from a high correlated color temperature, and low color-rendering index due to its deficiency in the red spectrum. In this study, glass beads (GB) with an average particle diameter of 10 μm were introduced to the conversion layer of a YAG:Ce3+ particulate-filled polydimethylsiloxane matrix composite structure and found to improve the optical features of the resulting composite.}, keywords = {}, pubstate = {published}, tppubtype = {article} } YAG:Ce3+ is a yellow-source compound commonly used in phosphor conversion layers for direct coating or remote phosphor configurations in LED illumination. This material, however, suffers from a high correlated color temperature, and low color-rendering index due to its deficiency in the red spectrum. In this study, glass beads (GB) with an average particle diameter of 10 μm were introduced to the conversion layer of a YAG:Ce3+ particulate-filled polydimethylsiloxane matrix composite structure and found to improve the optical features of the resulting composite. |
Zeren, Doğuş; Güden, Mustafa The increased compression strength of an epoxy resin with the addition of heat-treated natural nano-structured diatom frustules Journal Article Journal of Composite Materials, 51 (12), pp. 1681-1691, 2017. @article{doi:10.1177/0021998316669855, title = {The increased compression strength of an epoxy resin with the addition of heat-treated natural nano-structured diatom frustules}, author = {Doğuş Zeren and Mustafa Güden}, url = {https://doi.org/10.1177/0021998316669855}, doi = {10.1177/0021998316669855}, year = {2017}, date = {2017-01-01}, journal = {Journal of Composite Materials}, volume = {51}, number = {12}, pages = {1681-1691}, abstract = {Natural diatom frustules composing nanometer size silica particles were heat-treated at temperatures between 600 and 1200℃ for 2 h and used as filler/reinforcing agent (15 wt%) in an epoxy resin. The opal structure of as-received natural diatom frustules was transformed into cristobalite after the heat-treatment above 900℃. The epoxy resin test samples reinforced with heat-treated and as-received frustules and neat epoxy test samples were compression tested at the quasi-static strain rate of 7 × 10−3 s−1. The results showed that the inclusion of the frustules heat-treated at 1000℃ increased the compressive yield strength of the resin by 50%, while the addition of the diatom frustules heat-treated above and below 1000℃ and the as-received frustules increased the strength by ∼25% and 16%, respectively. The heat treatment above 1000℃ decreased the surface area of the frustules from 8.23 m2 g−1 to 3.46 m2 g−1. The cristobalite grains of the frustules heat-treated at 1000℃ was smaller than 100 nm, while the grain size increased to ∼500 nm at 1200℃. The increased compressive stresses of the resin at the specific heat treatment temperature (1000℃) were ascribed to nano size crystalline cristobalite grains. The relatively lower compressive stresses of the epoxy resin filled with frustules heat-treated above 1000℃ were attributed to the micro-cracking of the frustules that might be resulted from higher density of the cristobalite than that of the opal and accompanying reduction of the surface area and the surface pore sizes that might impair the resin-frustule interlocking and intrusion.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Natural diatom frustules composing nanometer size silica particles were heat-treated at temperatures between 600 and 1200℃ for 2 h and used as filler/reinforcing agent (15 wt%) in an epoxy resin. The opal structure of as-received natural diatom frustules was transformed into cristobalite after the heat-treatment above 900℃. The epoxy resin test samples reinforced with heat-treated and as-received frustules and neat epoxy test samples were compression tested at the quasi-static strain rate of 7 × 10−3 s−1. The results showed that the inclusion of the frustules heat-treated at 1000℃ increased the compressive yield strength of the resin by 50%, while the addition of the diatom frustules heat-treated above and below 1000℃ and the as-received frustules increased the strength by ∼25% and 16%, respectively. The heat treatment above 1000℃ decreased the surface area of the frustules from 8.23 m2 g−1 to 3.46 m2 g−1. The cristobalite grains of the frustules heat-treated at 1000℃ was smaller than 100 nm, while the grain size increased to ∼500 nm at 1200℃. The increased compressive stresses of the resin at the specific heat treatment temperature (1000℃) were ascribed to nano size crystalline cristobalite grains. The relatively lower compressive stresses of the epoxy resin filled with frustules heat-treated above 1000℃ were attributed to the micro-cracking of the frustules that might be resulted from higher density of the cristobalite than that of the opal and accompanying reduction of the surface area and the surface pore sizes that might impair the resin-frustule interlocking and intrusion. |
Shukla, Sudheesh K; Demir, Mustafa M; Govender, Penny P; Tiwari, Ashutosh; Shukla, S K Optical fibre based non-enzymatic glucose sensing over Cu2+-doped polyaniline hybrid matrix Journal Article Sensors and Actuators B: Chemical, 242 , pp. 522 - 528, 2017, ISSN: 0925-4005. @article{shukla2017522, title = {Optical fibre based non-enzymatic glucose sensing over Cu2+-doped polyaniline hybrid matrix}, author = {Sudheesh K Shukla and Mustafa M Demir and Penny P Govender and Ashutosh Tiwari and S K Shukla}, url = {http://www.sciencedirect.com/science/article/pii/S0925400516318615}, doi = {https://doi.org/10.1016/j.snb.2016.11.062}, issn = {0925-4005}, year = {2017}, date = {2017-01-01}, journal = {Sensors and Actuators B: Chemical}, volume = {242}, pages = {522 - 528}, abstract = {The opto-chemical glucose sensing over cupric ion doped polyaniline (Cu+2/PANI) hybrid polymer matrix coated glass rod based optode has been demonstrated.Cu+2/PANI hybrid matrix was synthesized by in situ chemical polymerization of intrinsically functionalized aniline. Furthermore, developed optode has been explored for direct oxidisation of glucose on Cu+2/PANI hybrid matrix for non-enzymatic glucose sensing employing O-dianisidine indicator system. The proposed glucose sensor works well in range of 50mg/dL–200mg/dL with response time of 15s in artificial as well as in biological samples along with 40days of lifespan.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The opto-chemical glucose sensing over cupric ion doped polyaniline (Cu+2/PANI) hybrid polymer matrix coated glass rod based optode has been demonstrated.Cu+2/PANI hybrid matrix was synthesized by in situ chemical polymerization of intrinsically functionalized aniline. Furthermore, developed optode has been explored for direct oxidisation of glucose on Cu+2/PANI hybrid matrix for non-enzymatic glucose sensing employing O-dianisidine indicator system. The proposed glucose sensor works well in range of 50mg/dL–200mg/dL with response time of 15s in artificial as well as in biological samples along with 40days of lifespan. |
Kandemir, Ali; Ozden, Ayberk; Cagin, Tahir; Sevik, Cem Thermal conductivity engineering of bulk and one-dimensional Si-Ge nanoarchitectures Journal Article Science and Technology of Advanced Materials, 18 (1), pp. 187-196, 2017, (PMID: 28469733). @article{doi:10.1080/14686996.2017.1288065, title = {Thermal conductivity engineering of bulk and one-dimensional Si-Ge nanoarchitectures}, author = {Ali Kandemir and Ayberk Ozden and Tahir Cagin and Cem Sevik}, url = {https://doi.org/10.1080/14686996.2017.1288065}, doi = {10.1080/14686996.2017.1288065}, year = {2017}, date = {2017-01-01}, journal = {Science and Technology of Advanced Materials}, volume = {18}, number = {1}, pages = {187-196}, publisher = {Taylor & Francis}, note = {PMID: 28469733}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Yanilmaz, A; Tomak, A; Akbali, B; Bacaksiz, C; Ozceri, E; Ari, O; Senger, R T; Selamet, Y; Zareie, H M Nitrogen doping for facile and effective modification of graphene surfaces Journal Article RSC Adv., 7 , pp. 28383-28392, 2017. @article{C7RA03046K, title = {Nitrogen doping for facile and effective modification of graphene surfaces}, author = {A Yanilmaz and A Tomak and B Akbali and C Bacaksiz and E Ozceri and O Ari and R T Senger and Y Selamet and H M Zareie}, url = {http://dx.doi.org/10.1039/C7RA03046K}, doi = {10.1039/C7RA03046K}, year = {2017}, date = {2017-01-01}, journal = {RSC Adv.}, volume = {7}, pages = {28383-28392}, publisher = {The Royal Society of Chemistry}, abstract = {We report experimental and theoretical investigations of nitrogen doped graphene. A low-pressure Chemical Vapor Deposition (CVD) system was used to grow large-area graphene on copper foil, using ethylene as the carbon source. Nitrogen-doped graphene (N-graphene) was prepared by exposing the graphene transferred to different substrates to atomic nitrogen plasma. The effect of varying nitrogen flow rates on doping of graphene was investigated while keeping the power and time constant during the process. The N-graphene was characterized via Raman Spectroscopy, X-ray Photoelectron Spectroscopy (XPS), Scanning Tunneling Microscopy and Spectroscopy (STM and STS), and Fourier Transform Infrared spectroscopy (FTIR). Raman mapping of N-graphene was also performed to show homogeneity of nitrogen on the graphitic lattice. XPS results have revealed the presence of different nitrogen configurations in the graphitic lattice with similar doping concentrations. Density functional theory (DFT) based calculations showed that the periodic adsorption of N atoms predominantly occurs on top of the C atoms rather than through substitution of C in our N-graphene samples. Our results indicate a feasible procedure for producing N-graphene with homogenous and effective doping which would be valuable in electronic and optical applications.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We report experimental and theoretical investigations of nitrogen doped graphene. A low-pressure Chemical Vapor Deposition (CVD) system was used to grow large-area graphene on copper foil, using ethylene as the carbon source. Nitrogen-doped graphene (N-graphene) was prepared by exposing the graphene transferred to different substrates to atomic nitrogen plasma. The effect of varying nitrogen flow rates on doping of graphene was investigated while keeping the power and time constant during the process. The N-graphene was characterized via Raman Spectroscopy, X-ray Photoelectron Spectroscopy (XPS), Scanning Tunneling Microscopy and Spectroscopy (STM and STS), and Fourier Transform Infrared spectroscopy (FTIR). Raman mapping of N-graphene was also performed to show homogeneity of nitrogen on the graphitic lattice. XPS results have revealed the presence of different nitrogen configurations in the graphitic lattice with similar doping concentrations. Density functional theory (DFT) based calculations showed that the periodic adsorption of N atoms predominantly occurs on top of the C atoms rather than through substitution of C in our N-graphene samples. Our results indicate a feasible procedure for producing N-graphene with homogenous and effective doping which would be valuable in electronic and optical applications. |
İncel, Anıl; Akın, Osman; Çağır, Ali; Yıldız, Ümit Hakan; Demir, Mustafa M Smart phone assisted detection and quantification of cyanide in drinking water by paper based sensing platform Journal Article Sensors and Actuators B: Chemical, 252 , pp. 886 - 893, 2017, ISSN: 0925-4005. @article{incel2017886b, title = {Smart phone assisted detection and quantification of cyanide in drinking water by paper based sensing platform}, author = {Anıl İncel and Osman Akın and Ali Çağır and Ümit Hakan Yıldız and Mustafa M Demir}, url = {http://www.sciencedirect.com/science/article/pii/S0925400517310559}, doi = {https://doi.org/10.1016/j.snb.2017.05.185}, issn = {0925-4005}, year = {2017}, date = {2017-01-01}, journal = {Sensors and Actuators B: Chemical}, volume = {252}, pages = {886 - 893}, abstract = {An organometallic dye, europium tetrakis dibenzoylmethide triethylammonium (EuD4TEA) and gold nanoparticles (Au NPs) impregnated paper based sensor platform have been utilized for development of fluorescence turn-on cyanide assay in aqueous media. The ordinary filter paper with 6μ m pore size were employed as solid support that facilitates impregnation of EuD4TEA and gold nanoparticles and provides durability. Detection mechanism relying on two processes (i) dissolution of gold nanoparticles causing fluorescence recovery and (ii) ligand exchange of triethyl amine with CN group stimulating cyanide specific fluorescence enhancement. The paper platform exhibit naked eye distinguishable color transition upon CN− addition from 10−2 to 10−12M. To standardize the methodology a homemade image processing algorithm has been developed that enabling calibration of color change and quantify CN− concentration. The described algorithm is applicable to Android smart phones and facilitate transforming these devices into a quantitative cyanide detector. The overall methodology provides instrument free cyanide detection and therefore rapid control of water quality and safety at off-field conditions.}, keywords = {}, pubstate = {published}, tppubtype = {article} } An organometallic dye, europium tetrakis dibenzoylmethide triethylammonium (EuD4TEA) and gold nanoparticles (Au NPs) impregnated paper based sensor platform have been utilized for development of fluorescence turn-on cyanide assay in aqueous media. The ordinary filter paper with 6μ m pore size were employed as solid support that facilitates impregnation of EuD4TEA and gold nanoparticles and provides durability. Detection mechanism relying on two processes (i) dissolution of gold nanoparticles causing fluorescence recovery and (ii) ligand exchange of triethyl amine with CN group stimulating cyanide specific fluorescence enhancement. The paper platform exhibit naked eye distinguishable color transition upon CN− addition from 10−2 to 10−12M. To standardize the methodology a homemade image processing algorithm has been developed that enabling calibration of color change and quantify CN− concentration. The described algorithm is applicable to Android smart phones and facilitate transforming these devices into a quantitative cyanide detector. The overall methodology provides instrument free cyanide detection and therefore rapid control of water quality and safety at off-field conditions. |
İncel, Anıl; Varlikli, Canan; McMillen, Colin D; Demir, Mustafa M Triboluminescent Electrospun Mats with Blue-Green Emission under Mechanical Force Journal Article The Journal of Physical Chemistry C, 121 (21), pp. 11709-11716, 2017. @article{doi:10.1021/acs.jpcc.7b02875c, title = {Triboluminescent Electrospun Mats with Blue-Green Emission under Mechanical Force}, author = {Anıl İncel and Canan Varlikli and Colin D McMillen and Mustafa M Demir}, url = {https://doi.org/10.1021/acs.jpcc.7b02875}, doi = {10.1021/acs.jpcc.7b02875}, year = {2017}, date = {2017-01-01}, journal = {The Journal of Physical Chemistry C}, volume = {121}, number = {21}, pages = {11709-11716}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Celik, Asli; Koc, Gonca; Erdogan, Emre; Shahwan, Talal; Baba, Alper; Demir, Mustafa M Use of electrospun fiber mats for the remediation of hypersaline geothermal brine Journal Article DESALINATION AND WATER TREATMENT, 62 , pp. 94-100, 2017. @article{ISI:000403566800010, title = {Use of electrospun fiber mats for the remediation of hypersaline geothermal brine}, author = {Asli Celik and Gonca Koc and Emre Erdogan and Talal Shahwan and Alper Baba and Mustafa M Demir}, url = {http://openaccess.iyte.edu.tr/handle/11147/6328}, doi = {http://doi.org/10.5004/dwt.2017.20151}, year = {2017}, date = {2017-01-01}, journal = {DESALINATION AND WATER TREATMENT}, volume = {62}, pages = {94-100}, abstract = {Geothermal brines display high contents of various metal ions that can adversely affect surface and groundwater resources. Nevertheless, it is possible to sequestrate these metals and use some of them in certain engineering applications. The aim of this study was to fabricate electrospun chitosan fiber mats and remove heavy metal cations from geothermal brine of the Tuzla geothermal field (TGF) by employing these mats. TGF is located on the Biga Peninsula in the northwestern part of Turkey. The brine of TGF has high salinity (EC > 91 mS/cm) and high temperature ( reservoir temperature is 173 degrees C). The brine is rich in terms of metal cations. For instance, the concentration of lithium ion in geothermal fluid ranges from 17 to 35 mg/L, with little seasonal variations. A horizontal electrospinning setup was employed to obtain a non-woven mat comprising submicron diameter chitosan fibers at 2.0 kV.cm(-1). This material was then utilized as a stable membrane for the removal of metal ions present in the brine through sorption at 25 degrees C overnight. The results showed that the chitosan fiber mats sequestrate various ions in the brine. Under the studied conditions, the material was capable of removing 46%, 44%, 50%, 44%, 40%, 67% and 48% of Li+, Mg2+, Ba2+, Sr2+, Mn2+, Ca2+ and K+ from the geothermal brine, respectively.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Geothermal brines display high contents of various metal ions that can adversely affect surface and groundwater resources. Nevertheless, it is possible to sequestrate these metals and use some of them in certain engineering applications. The aim of this study was to fabricate electrospun chitosan fiber mats and remove heavy metal cations from geothermal brine of the Tuzla geothermal field (TGF) by employing these mats. TGF is located on the Biga Peninsula in the northwestern part of Turkey. The brine of TGF has high salinity (EC > 91 mS/cm) and high temperature ( reservoir temperature is 173 degrees C). The brine is rich in terms of metal cations. For instance, the concentration of lithium ion in geothermal fluid ranges from 17 to 35 mg/L, with little seasonal variations. A horizontal electrospinning setup was employed to obtain a non-woven mat comprising submicron diameter chitosan fibers at 2.0 kV.cm(-1). This material was then utilized as a stable membrane for the removal of metal ions present in the brine through sorption at 25 degrees C overnight. The results showed that the chitosan fiber mats sequestrate various ions in the brine. Under the studied conditions, the material was capable of removing 46%, 44%, 50%, 44%, 40%, 67% and 48% of Li+, Mg2+, Ba2+, Sr2+, Mn2+, Ca2+ and K+ from the geothermal brine, respectively. |