Şentürk, Ufuk
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Senturk, U.
Senturk, Ufuk
Şentürk, U.
Şentürk, U
Senturk, U
Senturk, Ufuk
Şentürk, U.
Şentürk, U
Senturk, U
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03.09. Department of Materials Science and Engineering
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Former Staff
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Sustainable Development Goals
1NO POVERTY
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2ZERO HUNGER
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3GOOD HEALTH AND WELL-BEING
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4QUALITY EDUCATION
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5GENDER EQUALITY
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6CLEAN WATER AND SANITATION
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7AFFORDABLE AND CLEAN ENERGY
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8DECENT WORK AND ECONOMIC GROWTH
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9INDUSTRY, INNOVATION AND INFRASTRUCTURE
3
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10REDUCED INEQUALITIES
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11SUSTAINABLE CITIES AND COMMUNITIES
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12RESPONSIBLE CONSUMPTION AND PRODUCTION
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13CLIMATE ACTION
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14LIFE BELOW WATER
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15LIFE ON LAND
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16PEACE, JUSTICE AND STRONG INSTITUTIONS
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17PARTNERSHIPS FOR THE GOALS
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18
Citations
357
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10
This researcher does not have a WoS ID.
Scholarly Output
7
Articles
4
Views / Downloads
5966/4672
Supervised MSc Theses
3
Supervised PhD Theses
0
WoS Citation Count
91
Scopus Citation Count
98
Patents
1
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0
WoS Citations per Publication
13.00
Scopus Citations per Publication
14.00
Open Access Source
7
Supervised Theses
3
| Journal | Count |
|---|---|
| Construction and Building Materials | 1 |
| Geothermics | 1 |
| Journal of Luminescence | 1 |
| Optical Materials | 1 |
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7 results
Scholarly Output Search Results
Now showing 1 - 7 of 7
Master Thesis Investigation of Biological and Organic Molecular Assembly(Izmir Institute of Technology, 2016) Mendirek, Gizem; Zareie, Hadi; Şentürk, UfukSelf-assembled monolayers (SAMs) are well-defined and ordered films of molecules that are spontaneously deposited on a surface. By designing molecules with desired head groups for binding specific surfaces, such SAMs can be interesting for a lot of applications such as molecular electronics and biosensors. In this study, SAMs of organic and biological molecules have been investigated. SAMs of thiophenol, a newly designed Schiff base (E)-4-((4-(phenylethynyl)benzylidene)amino)benzenethiol molecule, a newly designed 4-(4,7-di(thiophen-2-yl)-1H-benzo[d]imidazol-2-yl)benzaldehyde monomer were studied. Mixed SAMs of biotin and streptavidin and graphite binding peptide assemblies are also studied. SAMs were prepared by solution phase method. The gold surface and graphite surface were used as a substrate, because they are both chemically inert to oxidation and flat surfaces. Scanning Tunneling Microscope (STM) was the main experimental technique used here. It was used to obtain images of SAMs at an atomic scale. Scanning Tunneling Spectroscopy (STS) was used to provide information about the local density of states of molecules. Spectroscopic Ellipsometry (SE) was used to measure the monolayer thickness. Contact Angle Measurements was used to determine the surface wettability. X-Ray Photoelectron Spectroscopy (XPS) was used to analyze surface chemistry of SAMs. Surface-Enhanced Raman Spectroscopy (SERS) was used to identify the molecules on a surface.Article Citation - WoS: 46Citation - Scopus: 50Investigation of Europium Concentration Dependence on the Luminescent Properties of Borogermanate Glasses(Elsevier Ltd., 2017) Gökçe, Melis; Şentürk, Ufuk; Uslu, Deniz K.; Burgaz, Gözde; Şahin, Yüksel; Gökçe, Aytaç GürhanIn 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=1–9 mol%) 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 900 nm 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=2 mol%. 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.Master Thesis Investigation Od the Surfaces of Dealkalized and Wethered Float Glass(Izmir Institute of Technology, 2016) Seziş, Ümmügülsüm; Şentürk, Ufuk; Zareie, Hadi M.In this study, the effects of surface dealkalization due to SO2 or SO3 gas treatment of commercial soda lime silica float glass on the weathering behavior was investigated. Only the air side of the glass was studied. The changes in the glass surface were analyzed for their topography and structure. The surface topography was studied using atomic force microscopy (AFM). The findings show the formation of micro-cracks on the surfaces of as-produced glass surfaces when treated with sulfur gas. The weathered surfaces show an increased roughness with increased weathering. The surface structure was investigated using attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy, specular reflectance infrared (SR-IR) spectroscopy, and micro-Raman spectroscopy techniques The results of the studies, ATR-FTIR and SR-IR techniques provided a reasonable insight on the surface structural changes while micro-Raman spectroscopy failed to detects these differences. ATR-FTIR and SR-IR the overall comparison of the effects of peak position with and without sulfur gas treatment suggests a wide scatter within each group. This scatter implies that sulfur gas treatment does not have any statistically significant effects. Also, the change in peak positions are no clear evidence of a decreasing or increasing peak position as the weathering period is increased by weathering effect. Additionally, the calculated penetration depth is found to be ~0,6-1 μm for these techniques. Namely, the penetration depth greater than the surface modification was observed. The results showed was not significantly affected by the surface dealkalization and weathering reactions. The analysis of the surface topography using AFM technique showed the formation of micro-cracks like features on the surfaces of sulfur treated glasses. These features are thought to occur under the sodium sulfate salt residue that is formed during the high temperature dealkalization reactions on the surface. Results sample preparation, i.e. cleaning, was found to have a significant effect on the surface properties. A method has been developed to minimize the effects of sample preparation on the surface of the glass.Article Citation - WoS: 26Citation - Scopus: 26Optical Enhancement of Phosphor-Converted Wleds Using Glass Beads(Elsevier Ltd., 2017) Güner, Tuğrul; Şentürk, Ufuk; Demir, Mustafa MuammerYAG: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.Article Citation - WoS: 6Citation - Scopus: 6The Expansion Behavior of Slurries Containing Recycled Glass Powder Carboxymethyl Cellulose, Lime and Aluminum Powder(Elsevier, 2020) Zeren, Doğuş; Şentürk, Ufuk; Güden, MustafaThe rheology and foaming/expansion of the slurries of a waste/recycled glass powder with 50, 55 and 60 wt% of solid (glass powder) were experimentally investigated. The glass powder slurries were foamed using aluminum powder as foaming agent (0.75 wt%) and calcium hydroxide as activator (1 wt%). Sodium carboxymethyl cellulose (CMC) was added to the slurries as a binder with the amounts between 0 and 4 wt%. The expansions of the slurries were measured in-situ using a laser sensor and reported as percent volume expansion. The CMC-addition increased the viscosities of the slurries, particularly the fine size powder slurries. The slurries with the relatively low-viscosity exhibited lower initial expansion rates compared to the slurries with the relatively high-viscosity. The maximum expansions of the slurries increased from 300 to 350%, when the viscosity increased to 5 Pa s and reached a steady value around 400% between 5 and 50 Pa s. The expansions of the slurries could not be achieved above 50 Pa s since they became too thick to be foamed. The foam samples made from the slurries with 55 and 60 wt% of solid and sintered at 700 and 750 degrees C for 30 min had the average densities between 355 and 530 kg m(-3) and the average compressive strengths between 0.2 and 0.5 MPa. Increasing sintering time to 60 min at 750 degrees C increased the average compressive strength from 0.5 to 1.5 MPa for the foam samples made from the slurry with 60 wt% of solid. These proved that both sintering temperature and time were effective in increasing the compressive strengths of the foamed structures. The thermal conductivities of the sintered foam samples with the densities of 355 and 504 kg m(-3) were measured 0.042 and 0.057 W m(-1) K-1, respectively. (C) 2019 Elsevier Ltd. All rights reserved.Article Citation - WoS: 13Citation - Scopus: 16Experimental Modeling of Silicate-Based Geothermal Deposits(Elsevier Ltd., 2017) Çelik, Aslı; Topçu, Gökhan; Baba, Alper; Akdoğan, Yaşar; Şentürk, Ufuk; Demir, Mustafa MuammerScaling 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.Master Thesis Characterization and Expansion Behaviour of Perlite(Izmir Institute of Technology, 2016) Gül, Dilek; Şentürk, Ufuk; Demir, Mustafa MuammerPerlite is a silica-based organic glass. When it is instantaneously heated, it shows expansion by releasing a certain amount of water. Approximately 70% of perlite reserves in the world are found in Turkey. The porous structure of expanded perlite leads to use this material in many industrial areas; therefore, this is highly advantageous from the economic standpoint. In this study, the expansion behaviours of perlite samples, which were taken from İzmir (Bergama Mine), Kütahya (Avdan Mine), and Erzincan (Mollatepe Mine) were both characterized and investigated in the laboratory. The instrumentation techniques, X-ray Diffraction (XRD), X-ray Fluorescence (XRF), Scanning Electron Microscopy (SEM), Thermogravimetric Analysis (TGA), and Optic Microscope were used to characterize the perlite. The determination of the amorphous and crystal structure of perlite, the chemical composition of perlite, the measurement of loss of mass, the morphological characterization of perlite, and the form of raw and expanded perlite samples were obtained by XRD, XRF, TGA, SEM and Optic Microscopy, respectively. Four different heat treatments as 600 ˚C, 800 ˚C , 900 ˚C and 1000 ˚C and four different sizes 400-500 μm, 315-400 μm, 200-315 μm and 160-200 μm were conducted in the laboratory and the their bulk volumes and densities were compared before and after heat treatment. The perlite sample from Bergama 01 showed the largest expansion in all samples. As results of the analyses, the amount of crystal and water release in the perlite which had an influence on expansion process were consistent with the literature. The analyses were conducted until 1000 ˚C due to forming sinter above softening temperature. Additionally, the expanded perlite samples in the industrial furnace were compared with the expanded perlite samples in the laboratory more porous structure was observed. As a conclusion, the perlite samples from the different regions of Turkey were characterized and analyzed in terms of expansion behaviour in this study.