Yazarlar
- Pat, Suat(9)
- Özen, Soner(9)
- Korkmaz, Şadan(8)
- Şenay, Volkan(8)
- Cuce, Erdem(6)
- Cuce, Pinar Mert(5)
- Dertli, Enes(4)
- Artar, Musa(3)
- Mohammadigharehbagh, Reza(3)
- Yilmaz, Mustafa Tahsin(3)
- Akkus, B.(2)
- Bilgiç, Eyüp(2)
- Cankurt, Hasan(2)
- Demirtas, M.(2)
- Dogan, G.S.(2)
- Geçici, Birol(2)
- Gülmez, Gülay(2)
- Kosunalp, Selahattin(2)
- Mutlu, R.B.C.(2)
- Oktem, Y.(2)
- Purcek, G.(2)
- Sagdic, Osman(2)
- Tatlisu, Nevruz Berna(2)
- Yalcin, L.S.(2)
- Abdioglu, M.(1)
- Akšić, Milica Fotirić(1)
- Alim, Bünyamin(1)
- Arici, Muhammet(1)
- Avsar, Mustafa(1)
- Ağar, Berrin(1)
- Beydemir, Şükrü(1)
- Birol, Onur(1)
- Boncukçuoǧlu, Recep(1)
- Bozkurt, Fatih(1)
- Cakir, Ozlem(1)
- Cansiz, A.(1)
- Cengiz, İbrahim(1)
- Cetin, M.E.(1)
- Ceviz, M.A.(1)
- Cicek, Perihan Kubra(1)
Yayınlar
- MakaleYalnız künye2016Characterisation of lactic acid bacteria from Turkish sourdough and determination of their exopolysaccharide (EPS) production characteristics
Dertli, Enes; Mercan, Emin; Arici, Muhammet; Yilmaz, Mustafa Tahsin; Sağdiç, Osman
A total of 249 Lactic Acid Bacteria (LAB) isolates were found in traditional Turkish wheat sourdoughs from Eastern Black Sea region of Turkey. Genotypic characterization of these isolates revealed the presence of 47 distinct LAB strains belonging to 11 different species: Lactobacillus plantarum, Lactobacillus paraplantarum, Lactobacillus curvatus, Lactobacillus rossiae, Lactobacillus sanfranciscensis, Lactobacillus brevis, Lactobacillus paralimentarius, Weissella paramesenteroides, Leuconostoc mesenteroides, Leuconostoc pseudomesenteroides and Weissella cibaria. The sourdough LAB microbiota differed depending on the sample origin and the collection period and heterofermentative LAB were dominant. The number of different species within a sourdough varied from 3 to 6 with the association of different hetero- and homofermentative LAB species. Exopolysaccharide (EPS) production characteristics of the isolates were determined and strain specific properties appeared to be important for the final EPS yields. Genes required for homopolysaccharide (gtf and lev) and heteropolysaccharide (epsA, epsB, p-gtf) production were PCR detected and several distribution patterns were observed. Results of this study confirmed the biodiversity of LAB species in traditional Turkish sourdough and highlighted the importance of EPS production in sourdough LAB strains.
AtıfScopus174
İncele - Derleme MakaleYalnız künye2016Influence of oxygen partial pressure on the metastable copper oxide thin films
Geçici, Birol; Korkmaz, Šadan; Özen, Soner; Šenay, Volkan; Pat, Suat
Paramelaconite (Cu4O3) is a metastable copper oxide. Metastable copper oxide thin films were deposited on glass substrates by reactive RF magnetron sputtering in argon (Ar) and oxygen (O2) gas mixture atmospheres. Ar/O2 gas ratios in the sputtering ambient were chosen as 1/1 and 1/9. The surface and optical properties were determined by X-ray diffractometer (XRD), atomic force microscope (AFM) and UV-Vis spectrophotometer. The XRD patterns of the samples exhibited single strong diffraction peaks at 35.39° and 35.49° , corresponding to the (202) peak of Cu4O3. The mean thickness values were measured as 100 nm and 80 nm for the films deposited at 1/1 and 1/9 Ar/O2 gas ratios, respectively. The samples showed low transmittance and high absorbance in the high frequency region.
AtıfScopus1WoS1
İncele - MakaleYayıncıda açık erişim2016The influence of voltage applied between the electrodes on optical and morphological properties of the InGaN thin films grown by thermionic vacuum arc
Özen, Soner; Şenay, Volkan; Pat, Suat; Korkmaz, Şadan
The aim of this research is to investigate the optical and morphological properties of the InGaN thin films deposited onto amorphous glass substrates in two separate experiments with two different voltages applied between the electrodes, i.e. 500 and 600 V by means of the thermionic vacuum arc technique. This technique is original for thin film deposition and it enables thin film production in a very short period of time. The optical and morphological properties of the films were investigated by using field emission scanning electron microscope, atomic force microscope, spectroscopic ellipsometer, reflectometer, spectrophotometer, and optical tensiometer. Optical properties were also supported by empirical relations. The deposition rates were calculated as 3 and 3.3 nm/sec for 500 and 600 V, respectively. The increase in the voltage also increased the refractive index, grain size, root mean square roughness and surface free energy. According to the results of the wetting experiments, InGaN samples were low-wettable, also known as hydrophobic. SCANNING 38:14-20, 2016.
AtıfScopus22WoS23İncele - MakaleYalnız künye2016A multi-criteria neutrosophic group decision making method based TOPSIS for supplier selection
Şahin, Ridvan; Yigider, Muhammet
The process of multi-criteria group decision making (MCGDM) is of determining the best choice among all of the probable alternatives. The problem of supplier selection on which decision maker has usually vague and imprecise knowledge is a typical example ofmulti criteria group decision-making problem. The conventional crisp techniques has notmuch effective for solvingMCDMproblems because of imprecise or fuzziness nature of the linguistic assessments. To find the exact values for MCGDM problems is both difficult and impossible in more cases in real world. So, it is more reasonable to consider the values of alternatives according to the criteria as single valued neutrosophic sets (SVNS). This paper deal with the technique for order preference by similarity to ideal solution (TOPSIS) approach and extend the TOPSIS method to MCGDM problem with single valued neutrosophic information. The value of each alternative and the weight of each criterion are characterized by single valued neutrosophic numbers. Here, the importance of criteria and alternatives is identified by aggregating individual opinions of decision makers (DMs) via single valued neutrosophic weighted averaging (SVNWA) operator. The proposed method is, easy use, precise and practical for solving MCGDM problem with single valued neutrosophic data. Finally, to show the applicability of the developed method, a numerical experiment for supplier choice is given as an application of single valued neutrosophic TOPSIS method at end of this paper.
AtıfScopus42İncele - MakaleYalnız künye2016Applicability of statistical process control for surface modification plant and properties of coated calcite
Ucurum, Metin; Malgir, Eda; Deligezen, Hamdi; Karaer, Necmettin; Avsar, Mustafa
Due to its low surface energy, easy dispersion, high homogeneity and whiteness, coated (modified) calcite has increasingly been used in many industries, particularly in the plastics. The demand for this product will most likely increase in the years to come. Surface modification of calcite with a fatty acid would lead to a great expansion of industrial applications. The color values of coated calcite products are the first quality parameter. Therefore, it is very important to monitor the variations in the color characteristics of the coated calcite products. It is well known that statistical process control (SPC) techniques have been widely used in the many industries. In the present study, the surface of micronized calcite was coated with stearic acid by a pin mill. X-R control graphics and process capability index were applied for monitoring variations in quality control based on color parameters (L*,a*and b*) for the pin mill plant. In addition, active ratio, particle size distribution, whiteness parameters, BET, FTIR, TGA-DTA and SEM were then determined on a coated calcite sample. The results show that the pin mill plant seems under control and the coating technology is very effective in modifying the surface of micronized calcite.products.
AtıfScopus3İncele - MakaleYalnız künye2016Properties of NaOH activated geopolymer with marble, travertine and volcanic tuff wastes
Tekin, Ilker
In this study, geopolymer composite pastes (GCM) were produced using wastes of marble, travertine and natural pozzolan, with 1 M, 5 M and 10 M NaOH as alkali-activator. Curing process were done at 20, 45 and 75 °C temperatures for 24 h in an oven. And after that GCMs were exposed to wet and dry condition separately. The strength tests were done on the 2nd, 3rd, 7th, 28th and 90th days of curing period. The compressive strengths of the specimens in the wet conditions were reduced depending on time, but in dry conditions were increased with curing time.
AtıfScopus137İncele - BildiriYalnız künye2016Impedance analysis of nano thickness layered AlGaN acoustic sensor deposited by thermionic vacuum arc
Özen, Soner; Bilgiç, Eyüp; Gülmez, Gülay; Şenay, Volkan; Pat, Suat; Korkmaz, Şadan; Mohammadigharehbagh, Reza; Akkus, B.; Dogan, G.S.; Mutlu, R.B.C.
In this study, AlGaN acoustic sensor was deposited on aluminum metal substrate by thermionic vacuum arc (TVA) method for the first time. Gallium materials are used in many applications for optoelectronic device and semiconductor technology. Thermionic vacuum arc is the deposition technology for the variously materials and applications field. The thickness of the acoustic sensor is in deposited as nano layer. Impedance analyses were realized. Also, TVA production parameters and some properties of the deposited layers were investigated. TVA is a fast deposition technology for the gallium compounds and doped gallium compounds. Obtained results show that AlGaN materials are very promising materials. Moreover, these acoustic sensors have been produced by TVA technology.
AtıfScopus1WoS1İncele - MakaleYalnız künye2016Optimum design of steel space frames including soil-structure interaction
Daloglu, Ayse T.; Artar, Musa; Özgan, Korhan; Karakas, Ali İ.
The effect of soil-structure interaction on the optimum design of steel space frames is investigated using metaheuristic algorithms. Three-parameter elastic foundation model is used to incorporate soil-structure interaction. A computer program is developed in MATLAB interacting with SAP2000-OAPI for two way data flow in all optimization procedures. Optimum design of space frames is formulated according to LRFD-AISC (Load and Resistance Factor Design, American Institute of Steel Construction) specifications. The parameters of foundation model are obtained by using soil surface displacements. It is concluded that consideration of soil-structure interaction ends up with heavier frames, and method is applicable for practical purposes.
AtıfScopus27WoS28İncele - MakaleYayıncıda açık erişim2016Practical implementation and stability analysis of ALOHA-Q for wireless sensor networks
Kosunalp, Selahattin; Mitchell, Paul Daniel; Grace, David; Clarke, Tim
This paper presents the description, practical implementation, and stability analysis of a recently proposed, energy-efficient, medium access control protocol for wireless sensor networks, ALOHA-Q, which employs a reinforcement-learning framework as an intelligent transmission strategy. The channel performance is evaluated through a simulation and experiments conducted using a real-world test-bed. The stability of the system against possible changes in the environment and changing channel conditions is studied with a discussion on the resilience level of the system. A Markov model is derived to represent the system behavior and estimate the time in which the system loses its operation. A novel scheme is also proposed to protect the lifetime of the system when the environment and channel conditions do not sufficiently maintain the system operation.
AtıfScopus7İncele - MakaleYalnız künye2016Novel glazing technologies to mitigate energy consumption in low-carbon buildings: A comparative experimental investigation
Cuce, Erdem; Cuce, Pinar Mert; Riffat, Saffa
Buildings play a key role in total world energy consumption as a consequence of poor thermal insulation characteristics of facade materials. Among the elements of a typical building envelope, windows are responsible for the greatest energy loss because of their notably high overall heat transfer coefficients. About 60% of heat loss through the building fabric can be attributed to the glazed areas. In this respect, novel cost-effective glazing technologies are needed to mitigate energy consumption, and thus to achieve the latest targets toward low/zero carbon buildings. Therefore in this study, three unique glazing products called vacuum tube window, heat insulation solar glass and solar pond window which have recently been developed at the University of Nottingham are introduced, and thermal performance analysis of each glazing technology is done through a comparative experimental investigation for the first time in literature. Standardized co-heating test methodology is performed, and overall heat transfer coefficient (U-value) is determined for each glazing product following the tests carried out in a calibrated environmental chamber. The research essentially aims at developing cost-effective solutions to mitigate energy consumption because of windows. The results indicate that each glazing technology provides very promising U-values which are incomparable with conventional commercial glazing products. Among the samples tested, the lowest U-value is obtained from the vacuum tube window by 0.40W/m2K, which corresponds to five times better thermal insulation ability compared to standard air filled double glazed windows.
AtıfScopus35WoS33İncele - MakaleYalnız künye2016Effects of grain size on room temperature deformation behavior of Zn–22Al alloy under uniaxial and biaxial loading conditions
Cetin, M.E.; Demirtas, M.; Sofuoglu, H.; Cora, Ö.N.; Purcek, G.
Effects of grain size on room temperature (RT) deformation behavior of superplastic Zn–22Al alloy under uniaxial and biaxial loading conditions were investigated. Two–step equal channel angular pressing (ECAP) and subsequent annealing processes were applied to the alloy in order to obtain microstructures with various grain sizes ranging from submicron to micron sizes. Grain size of 200 nm was achieved after ECAP of the alloy, and it was increased up to ~2.60 µm by annealing at 250 °C for different time periods. Changes in deformation behaviors of the alloy with various grain sizes were found to be in good agreement under the uniaxial tensile and biaxial Erichsen test conditions. Increasing grain size decreased both the maximum elongation under uniaxial deformation and limiting dome height (LDH) under biaxial deformation. The high elongation to failure and LDH values for the samples with submicron grain size were attributed to their high strain rate sensitivity.
AtıfScopus20WoS19İncele - MakaleYayıncıda açık erişim2016Effect of external magnetic field on valence-electron structures of Fe and Ni in Invar, Permalloy and the other Fe-Ni alloys by using Kβ-to-Kα X-ray intensity ratios
Alim, Bünyamin; Han, Ibrahim; Demir, Lütfü
The effect of external magnetic field on the valence-electron structures of Fe and Ni in various Fe-Ni alloy compositions was investigated by using X-ray fluorescence spectroscopy. Kβ-to-Kα X-rayin-tensity ratios of Fe and Ni in Invar(Fe0.64Ni0.36), Permalloy(Fe0.20Ni0.80) and Fe N - i x 1x Firstly,(x=0, 0.40, 0.52, 0.55, 0.61, and 1) alloys were measured without any magnetic field and under 0.5 and 1 T external magnetic fields, separately. Later, the valence-electron structures of Fe and Ni in both pure form and alloys were obtained by comparison of measured X-ray intensity ratios with the results of multi-configurations Dirac-Fock (MCDF) calculations. The results obtained for valence-electron structures of Fe and Ni in various Fe-Ni alloys were evaluated in terms of magnetic field effect, delocalization and/or charge transfer phenomena. The results have shown that valence electron structure of Fe and Ni in Fe-Ni alloys are dependent on both external magnetic field and concentration of alloy elements.
AtıfScopus16WoS14İncele - MakaleYalnız künye2016Exergetic interrelation between an heat pump and components
Çakır, Uğur; Çomaklı, Kemal
In this study, the relation between the exergetic performance of the heat pump and its components are investigated experimentally by using an air to water heat pump. Moreover, the effects of the working conditions of the components on the exergetic performance of the system are exposed and discussed. An experimental air to water heat pump system was designed and built. The results were evaluated by comparing the components and heat pump according to their performances. 33–45% of the all destructed exergy of the heat pump system comes into existence in the compressor. The contribution of the condenser to the total exergy destruction rate of the heat pump is between 23% and 34%. Contribution of the compressor to the exergy destruction rate of heat pump decreases with an increase in the air temperature and it increases with a decrease in the air mass flow rate. Contribution of the compressor to the exergy destruction rate of heat pump decreases with an increase in the air temperature and it increases with a decrease in the air mass flow rate. In terms of exergetic performance of the heat pump, the importance and priority of the components vary with the heat source thermal conditions.
AtıfScopus15İncele - MakaleYalnız künye2016Optimum design of steel space frames under earthquake effect using harmony search
Artar, Musa
This paper presents an optimization process using Harmony Search Algorithm for minimum weight of steel space frames under earthquake effects according to Turkish Earthquake Code (2007) specifications. The optimum designs are carried out by selecting suitable sections from a specified list including W profiles taken from American Institute of Steel Construction (AISC). The stress constraints obeying AISC- Load and Resistance Factor Design (LRFD) specifications, lateral displacement constraints and geometric constraints are considered in the optimum designs. A computer program is coded in MATLAB for the purpose to incorporate with SAP2000 OAPI (Open Application Programming Interface) to perform structural analysis of the frames under earthquake loads. Three different steel space frames are carried out for four different seismic earthquake zones defined in Turkish Earthquake Code (2007). Results obtained from the examples show the applicability and robustness of the method.
AtıfScopus14İncele - MakaleYalnız künye2016Optical, morphological and mechanical properties of an Al-Al2O3 nanocomposite thin film grown by thermionic vacuum arc
Şenay, Volkan; Özen, Soner; Pat, Suat; Korkmaz, Şadan
An Al-Al2O3 nanocomposite thin film was deposited onto a glass substrate in high vacuum condition using Al2O3 pellets as source material by means of the thermionic vacuum arc technique in just 50 s. UV-visible spectrophotometer, optical reflectometer, spectroscopic ellipsometer, XRD, FESEM and AFM were employed to investigate the optical, structural morphological and mechanical properties of the produced film. The film exhibited a high transmittance (above 80%) in the 400-1000 nm region. The dispersion of the refractive index was discussed in terms of the single oscillator model. The optical band gap value derived from the Wemple-DiDomenico dispersion relationship was 5.7 eV. It was observed that the results of the optical investigations agreed well with Al2O3 thin films. XRD characterization showed that the film contained Al and Al2O3 phases. The FESEM analysis revealed that the film morphology had a dense characteristic. 2D and 3D AFM micrographs indicated a smooth surface with a low value of average roughness. When compared to the mechanical properties of Al2O3 thin films, it was observed that the hardness and Young's modulus reduced due to presence of ductile Al particles.
AtıfScopus9WoS8İncele - MakaleYalnız künye2016Development of a fermented ice-cream as influenced by in situ exopolysaccharide production: Rheological, molecular, microstructural and sensory characterization
Dertli, Enes; Toker, Omer S.; Durak, M. Zeki; Yilmaz, Mustafa T.; Tatlisu, Nevruz Berna; Sagdic, Osman; Cankurt, Hasan
This study aimed to investigate the role of in situ exopolysaccharide (EPS) production by EPS+ Streptococcus thermophilus strains on physicochemical, rheological, molecular, microstructural and sensory properties of ice cream in order to develop a fermented and consequently functional ice-cream in which no stabilizers would be required in ice-cream production. For this purpose, the effect of EPS producing strains (control, strain 1, strain 2 and mixture) and fermentation conditions (fermentation temperature; 32, 37 and 42°C and time; 2, 3 and 4 h) on pH, S. thermophilus count, EPS amount, consistency coefficient (K), and apparent viscosity (η50) were investigated and optimized using single and multiple response optimization tools of response surface methodology. Optimization analyses indicated that functional ice-cream should be fermented with strain 1 or strain mixture at 40-42°C for 4 h in order to produce the most viscous ice-cream with maximum EPS content. Optimization analysis results also revealed that strain specific conditions appeared to be more effective factor on in situ EPS production amount, K and η50 parameters than did fermentation temperature and time. The rheological analysis of the ice-cream produced by EPS+ strains revealed its high viscous and pseudoplastic non-Newtonian fluid behavior, which demonstrates potential of S. thermophilus EPS as thickening and gelling agent in dairy industry. FTIR analysis proved that the EPS in ice-cream corresponded to a typical EPS, as revealed by the presence of carboxyl, hydroxyl and amide groups with additional α-glycosidic linkages. SEM studies demonstrated that it had a web-like compact microstructure with pores in ice-cream, revealing its application possibility in dairy products to improve their rheological properties.
AtıfScopus86WoS74
İncele - MakaleYalnız künye2016Organic acids, sugars and mineral content of cherry laurel (laurocerasus officinalis roem) accessions in Turkey
Esringu, Aslihan; Akšić, Milica Fotirić; Ercisli, Sezai; Okatan, Volkan; Gozlekci, Adiye; Cakir, Ozlem
In this study we report on the content of organic acids, sugars and miner-als in the pulps of the twelve cherry laurel accessions most commonly consumedin eastern Black Sea Region. Malic acid was the dominant organic acid rangedfrom 43.27 (CL6) to 54.23 (CL3) mg/100 g fresh weight basis. The dominantsugars were glucose and fructose in the pulps that ranged from 4.83 (CL1) to5.74 (CL5) mg/100 g and 4.66 (CL3) to 5.53 (CL7) mg/100 g, respectively. Thepulp of cherry laurel was shown to be rich in potassium (187-241 mg), phos-phorus (26-45 mg), calcium (15-22 mg), magnesium (15-24 mg) and sodium(3.9-6.1 mg) in 100 g fruit pulp. The data may be useful in selecting wild ediblefruit species appropriate for incorporation into diets.
AtıfScopus5İncele - MakaleYayıncıda açık erişim2016Heavily carbon doped GaAs nanocrystalline thin film deposited by thermionic vacuum arc method
Pat, Suat; Korkmaz, Şadan; Özen, Soner; Şenay, Volkan
In this paper, we introduced a new different thin film deposition method for heavily carbon doped GaAs. Used method is thermionic vacuum arc (TVA) and first used for the carbon doping process. The method is very fast deposition process for the other growth method such as metal organic chemical vapor deposition, molecular beam epitaxy, molecular organic molecular beam epitaxy. The smallest grain size of GaAs and doped GaAs were obtained by carbon doping process. Mean crystalline size and height of crystalline size were found to be 3.4 nm and 4 nm, respectively. Crystal direction was found to be (022) plane and (024) plane for the sample at 45.322° and 75.060°, respectively. The production process and obtained results show that used methods is very simple, low cost, eco friendly and very fast method for the carbon doped GaAs.
AtıfScopus9WoS9İncele - BildiriYayıncıda açık erişim2016The effects of fuel type in synthesis of NiFe2O4 nanoparticles by microwave assisted combustion method
Karakaş, Zeynep Karcioǧlu; Boncukçuoǧlu, Recep; Karakaş, Ibrahim H.; Durak, R.; Tuzemen, S.
In this study, it was investigated the effects of the used fuels on structural, morphological and magnetic properties of nanoparticles in nanoparticle synthesis with microwave assisted combustion method with an important method in quick, simple and low cost at synthesis of the nanoparticles. In this aim, glycine, urea and citric acid were used as fuel, respectively. The synthesised nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer-Emmet-Teller surface area (BET), and vibrating sample magnetometry (VSM) techniques. We observed that fuel type is quite effective on magnetic properties and surface properties of the nanoparticles. X-ray difractograms of the obtained nanoparticles were compared with standard powder diffraction cards of NiFe2O4 (JCPDS Card Number 54-0964). The results demonstrated that difractograms are fully compatible with standard reflection peaks. According to the results of the XRD analysis, the highest crystallinity was observed at nanoparticles synthesized with glycine. The results demonstrated that the nanoparticles prepared with urea has the highest surface area. The micrographs of SEM showed that all of the nanoparticles have nano-crystalline behaviour and particles indication cubic shape. VSM analysis demonstrated that the type of fuel used for synthesis is highly effective a parameter on magnetic properties of nanoparticles.
AtıfScopus22İncele - Derleme MakaleYalnız künye2016Vacuum glazing for highly insulating windows: Recent developments and future prospects
Cuce, Erdem; Cuce, Pinar Mert
A comprehensive review of vacuum glazing technology from state-of-the-art developments to future prospects has been presented. The review has been conducted in a thematic way in order to allow an easier comparison, discussion and evaluation of the findings. First, a thorough overview of historical development of vacuum glazing has been given. Then, numerous experimental, theoretical, numerical and simulation works on the scope have been evaluated and the characteristic results from the said works have been analyzed. Commercial vacuum glazing products in market have been assessed in terms of several performance parameters such as overall heat transfer coefficient, visible light transmittance, solar heat gain coefficient and cost. Techno-economic and environmental aspects of vacuum glazing technology have also been discussed. It can be concluded from the results that overall heat transfer coefficient of a vacuum glazing can be reduced up to 0.20 W/m2K through optimized integrations with low-e coatings. The incomparable U-value range of vacuum glazing enables significant mitigation in energy consumption levels and greenhouse gas emissions. Retrofitting 25.6 million homes in the UK with vacuum glazing can provide a carbon abatement of about 40 million tonnes a year, which is very promising.
AtıfScopus138WoS117İncele