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Koleksiyondaki öğeler
- MakaleAçık Erişim2019Scopus SJRQ3A Differential Evolution Algorithm-Based Traffic Control Model for Signalized Intersections
Cakici, Ziya; Murat, Yetis Sazi
Sustainable management of traffic flows at signalized intersections is an important issue in terms of traffic engineering. The minimization of lost time, emission, fuel consumption, etc., can be achieved by optimization-based intersection management. In this study, a new traffic signal control model is developed for the management of three-leg signalized intersections. In the proposed model, signal timing and signal phasing are optimized simultaneously using Differential Evolution (DE) algorithm which is one of the population-based metaheuristic algorithms. The effectiveness of the model is tested on sample traffic scenarios with VISSIM simulation software considering average vehicle delay performance criteria. Results show that the proposed approach may reduce the average vehicle delay between the rates of 28%-42% and 3%-38% comparing to the optimum fixed-time signal control and vehicle-actuated signal control for tested scenarios, respectively.
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İncele - MakaleAçık Erişim2018Scopus SJRQ1Microbial species playing roles for the production of traditional Kasar cheese during pre-maturation period
Yuvaşen, Ayşe; Macit, Emine; Dertli, Enes
The microbial flora of traditional Kaşar cheese samples obtained from six dairy plants during pre-maturation period of Kaşar maturation was analysed. In total, 500 isolates of none-starter lactic acid bacteria (NSLAB) and 80 fungi isolates were isolated, and they were subjected to molecular discrimination by RAPD-PCR and rep-PCR analysis. Genotypic characterization of these isolates revealed the presence of 45 distinct strains belonging to 13 different NSLAB species with Lactobacillus paracasei as the dominant species. A rich yeast microflora in Kaşar samples was also observed with the presence of 19 distinct strains belonging to 8 different species with Pichia kudriavzevii as the dominant species. During this period, only two Penicillium species were found in Kaşar samples. This study confirmed the biodiversity of NSLAB and fungi microflora of Kaşar cheese during pre-maturation period, and these results are important for the development of starter cultures for Kaşar production at industrial level.
AtıfScopus18WoS14OpenAlex22İncele - MakaleAçık Erişim2019Scopus SJRQ1Characterization of a 4,6‑α‑glucanotransferase from Lactobacillus reuteri E81 and production of malto-oligosaccharides with immune-modulatory roles
İspirli, Hümeyra; Şimşek, Ömer; Skory, Christopher; Sağdıç, Osman; Dertli, Enes
A wide number of Lactic Acid Bacteria (LAB) species produce α-glucans with their ability to synthesize glucansucrases (GS) which use sucrose as substrate for the glucan production. Recently another group of enzymes in LAB gained special interest for their ability to produce α-glucans targeting the substrates containing α1-4-linkages and synthesizing new (α1-6) or (α1-3)–linkages as α‑glucanotransferases. In this study, a putative 4,6‑α‑glucanotransferase (GTFB) from sourdough isolate Lactobacillus reuteri E81 was identified and expressed in Escherichia coli. The biochemical characterization of the GTFB-E81 confirmed its function as it cleaved the α1-4-linkages in different substrates and produced new gluco-oligomers/polymers containing α1-6 linkages together with the α1-4-linkages detected by NMR analysis. GTFB-E81 produced malto-oligosaccharides targeting maltose and maltoheptaose as substrates with up to DP 8 detected by TLC and ESI-MS/MS analysis. The functional roles of these malto-oligosaccharides were determined by testing their immune-modulatory functions in HT29 cells and they triggered the production of anti-inflammatory 1L-4 and pro-inflammatory IL-12 cytokines.
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İncele - MakaleAçık Erişim2016Scopus SJRQ1Improvement in performance properties of asphalt using a novel boron-containing additive
Oruç, Şeref; Yılmaz, Bahadır
In current times, many additives are used to improve the performance characteristics of asphalt. In this study, a new additive that contains boron, given the short name of cyclic borate ester (CBE), was chemically synthesised in laboratory conditions. It was added to the asphalt binder as 1%, 2%, 4% and 6% ratios of asphalt by weight, and modified asphalt samples were produced. The effects of CBE on the conventional properties of asphalt binder (penetration, softening point, ductility, flash point, Fraass breaking point) were examined using a dynamic shear rheometer, rotational viscosity, a rolling thin film oven, a pressure aging vessel and bending beam rheometer test methods. Results showed that the use of CBE additive increased the hardness, softening point, viscosity, flash-point value and rutting resistance of asphalt binder and decreased temperature sensitivity. CBE also enhanced elastic responses (increased complex shear modulus and decreased phase angle), aging resistance and low-temperature cracking resistance and did not change the cohesion property.
AtıfScopus25WoS24OpenAlex28İncele - MakaleAçık Erişim2013Scopus SJRQ2New water mites of the family Hygrobatidae (Acari, Hydrachnidia) from Turkey
Esen, Yunus; Pešić, Vladimir; Erman, Orhan; Kaya, Yücel
In this study, the findings of three water mite species of the family Hygrobatidae collected from different streams in Turkey were evaluated. Hygrobates (s. str.) anatolicus Esen & Pešić, sp. n. is described as new for science. Hygrobates (Rivobates) diversiporus Sokolow, 1927 and Atractides (s. str.) nikooae Pešić, 2004, which were illustrated and thoroughly discussed, are new records for the Turkish fauna.
AtıfScopus9WoS6OpenAlex8İncele - MakaleAçık Erişim2016Scopus SJRQ2Maximizing deviation method for neutrosophic multiple attribute decision making with incomplete weight information
Şahin, Rıdvan; Liu, Peide
This paper develops a method for solving the multiple attribute decision-making problems with the single-valued neutrosophic information or interval neutrosophic information. We first propose two discrimination functions referred to as score function and accuracy function for ranking the neutrosophic numbers. An optimization model to determine the attribute weights that are partly known is established based on the maximizing deviation method. For the special situations where the information about attribute weights is completely unknown, we propose another optimization model. A practical and useful formula which can be used to determine the attribute weights is obtained by solving a proposed nonlinear optimization problem. To aggregate the neutrosophic information corresponding to each alternative, we utilize the neutrosophic weighted averaging operators which are the single-valued neutrosophic weighted averaging operator and the interval neutrosophic weighted averaging operator. Thus, we can determine the order of alternatives and choose the most desirable one(s) based on the score function and accuracy function. Finally, some illustrative examples are presented to verify the proposed approach and to present its effectiveness and practicality.
AtıfScopus151WoS130OpenAlex148İncele - MakaleAçık Erişim2013Scopus SJRQ4Analysis of amplitude and slope diffraction coefficients
Tabakcioglu, Mehmet Bariş; Cansiz, Ahmet
The diffraction mechanism is used for field prediction in both light and shadowed regions. Slope and amplitude diffraction coefficients are vital to predict the field strength at the receiver accurately. In this paper, amplitude and slope diffraction coefficients for one of the ray theoretical models, the slope uniform theory of diffraction with convex hull (S-UTD-CH) model, are analyzed. Moreover, diffraction coefficients are given for knife-edge and wedge structures.
- MakaleAçık Erişim2015Scopus SJRQ1The effect of starch modification and concentration on steady-state and dynamic rheology of meat emulsions
Genccelep, Huseyin; Saricaoglu, Furkan Turker; Anil, Munir; Agar, Berrin; Turhan, Sadettin
In this study, the effect of starch modification (NPS, native potato starch; AMS, acid modified starch; DMS, dextrinized modified starch; PGS, pre-gelatinized modified starch) and its concentrations (1, 2, 4wt%) on steady-state and dynamic rheological properties of meat emulsions were determined. Water-oil binding capacity and intrinsic viscosity of potato starch increased up to 5.07-0.90g/g, and 14.98mL/g, respectively, after modifying with pre-gelatinization method. The particle size of starches as average mean diameter ranged between 44.19μm and 293.06μm. The maximum solubility was obtained from DMS after heat treatment at 70°C being 48.22%, which means an increase about 3.06-fold in solubility as compared with NPS. The Ostwald-de Waele model was successfully used to describe the flow properties of meat emulsions (R2>0.961). While starch types did not affect the K values of emulsions (p>0.05), starch concentrations did (p<0.01). All studied emulsions exhibited non-Newtonian, pseudoplastic behavior since n values were lower than 1. Emulsion systems were characterized as weak gel-like macromolecular dispersions with storage modulus (G') much greater than loss modulus (G″). A modified Cox-Merz rule was applied by multiplying angular frequency with shift factors (αSF). Frequency dependence of complex modulus (G*) was studied to measure the strength of cross-linking protein network of emulsion systems by calculating a constant order of relaxation function (α) and concentration dependent stiffness parameter (Aα). It was concluded that PGS addition improved rheological properties of meat emulsions due to higher solubility, particle size, intrinsic viscosity, water-oil binding capacity than NPS.
AtıfScopus92WoS77OpenAlex92İncele - MakaleAçık Erişim2018Scopus SJRQ1Optimization of reactive powder concrete by means of barite aggregate for both neutrons and gamma rays
Gökçe, H. Süleyman; Yalçınkaya, Çağlar; Tuyan, Murat
High performance concrete has been often preferred in special engineering structures and in challenging composites products. Researchers have recently focused on the radiation shielding characteristics of these type concrete mixtures due to rising nuclear industry in the developing world. In the study, performance of reactive powder concrete was researched with regard to gamma-ray and neutron attenuation when its normal weight aggregate replaced with heavyweight aggregate (barite). For this purpose, reactive powder concrete mixtures were prepared 100% quartz aggregate, 100% barite aggregate and their blending 50–50%, by volume. Some physical and mechanical characteristics such as density, compressive strength, fracture energy, flexural strength and modulus of elasticity of the mixtures were determined. Gamma-ray attenuation coefficients and transmission thickness values were theoretically established for commonly known gamma energies (661.7, 1173.2 and 1332.5 keV). Optimization of the reactive powder mixtures was performed for both neutron and gamma-ray attenuation at 8 MeV. As a result, barite significantly increased the gamma-ray attenuation coefficients of reactive powder concrete. The mechanical performance of reactive powder concrete, however, was markedly reduced as a result of barite substitution. Replacement of quartz by barite aggregate has a more adverse impact on flexural strength than that of compressive strength. A mix that contains 40% barite aggregate of total aggregate volume was found as an optimum RPC mixture for simultaneously shielding neutrons and gamma rays.
AtıfScopus138WoS126OpenAlex141İncele - MakaleAçık Erişim2015Scopus SJRQ1Comparative study of the magnetic stiffness, levitation and guidance force properties of single and multi seeded YBCOs for different HTS-PMG arrangements
Ozturk, K.; Sahin, E.; Abdioglu, M.; Kabaer, M.; Celik, S.; Yanmaz, E.; Kucukomeroglu, T.
Abstract It is crucial to improve the magnetic levitation, guidance and stiffness performances of the HTS Maglev systems for real-scale applications. In this study, the magnetic levitation force, guidance force and magnetic stiffness values were determined for single and multi-seeded YBCOs on different PMGs in ZFC regime and different cooling heights (CHs) after the magnetic flux distributions simulation of the using PMGs. Implemented study showed that the additional downward PMs make an enhancing contribution on the magnetic levitation force, guidance force and magnetic stiffness of both single and multi-seeded YBCOs. It was also determined that both the force and stiffness ratios of multi-seeded YBCO to single-seeded YBCO increase with increasing CH, indicating that the multi-seeded YBCO has much more interaction domain than single-seeded at higher gaps. It is considered that the results obtained in this study are very useful in technological applications of Maglev and bearing systems, because there is no detailed study on the magnetic stiffness, levitation and guidance force comparison to clarify electromagnetic behavior of single and multi-seeded YBCOs for different HTS-PMG arrangements.
AtıfScopus42WoS39OpenAlex40İncele - MakaleAçık Erişim2018Scopus SJRQ1Structural analysis of the α-D-glucan produced by the sourdough isolate Lactobacillus brevis E25
Dertli, Enes; Colquhoun, Ian J.; Côté, Gregory L.; Le Gall, Gwénaëlle; Narbad, Arjan
Cereal-associated Lactic Acid Bacteria (LAB) are well known for homopolymeric exopolysaccharide (EPS) production. Herein, the structure of an EPS isolated from sourdough isolate Lactobacillus brevis E25 was determined. A modified BHI medium was used for production of EPS-E25 in order to eliminate potential contaminants. Analysis of sugar monomers in EPS revealed that glucose was the only sugar present. Structural characterisation of EPS by NMR and methylation analysis revealed that E25 produced a highly branched α-glucan with (α1 → 3) and (α1 → 6) glycosidic linkages, and was similar in structure to a previously reported EPS from Lactobacillus reuteri 180. The 1H and 13C NMR data were contrasted with newly recorded data for known polysaccharides (alternan, commercial dextran) which also contain α-(1,3,6)Glc branch points. It was found in both E25 EPS and alternan that NMR parameters could be used to distinguish glucose residues that had the same substitution pattern but occupied different positions in the structure.
AtıfScopus78WoS73OpenAlex80İncele - MakaleYalnız künye2015Scopus SJRQ3A study on optical, morphological and mechanical properties of Al2O3 ultra-thin films deposited by RF reactive magnetron sputtering
Pat, Suat; Özen, Soner; Şenay, Volkan; Aydoʇmuş, Tuna; Elmas, Saliha; Korkmaz, Şadan; Ekem, Naci; Balbaʇ, M. Zafer
The Al2O3 ultra-thin films with the thicknesses of 30 nm and 35 nm were deposited on glass microscope slides by a radio frequency reactive magnetron sputtering system. The optical, morphological and mechanical properties were investigated as function of the film thickness. The refractive index of the resulting Al2O3 ultra-thin film increased with the increasing thickness. Both the films showed high transparency of > 85% and low reflectivity of < 10% in the visible and near infrared region. A band gap of ∼8.65 eV was obtained for the 30 nm film and ∼7.53 eV for the 35 nm film from an empirical relation between refractive index and band gap. According to the results obtained from the AFM studies, the root mean square surface roughness of the films are 3.67 nm and 3.77 nm for the 30 nm and 35 nm film, respectively. The hardness and Young modulus values decreased with the increasing film thickness.
AtıfScopus8WoS7İncele - MakaleAçık Erişim2015Scopus SJRQ2The toxicological impacts of some heavy metals on carbonic anhydrase from gilthead sea bream (Sparus aurata) gills
Kaya, Elif Duygu; Söyüt, Hakan; Beydemir, Şükrü
It is known that heavy metals have toxic effects on fish. Insufficient measures are a serious problem in our country and around the world. This problem can threaten human health in areas where it is common for people to obtain nutrition from local bodies of water. In this study, the toxicological impacts of some heavy metals were investigated on carbonic anhydrase activity in gilthead gills. Carbonic anhydrase (CA) was purified from gilthead sea bream (Sparus aurata) gills with a specific activity of 2872.92EUmg-1 and a yield of 32.84% using affinity chromatography. The overall purification was approximately ~84-fold. SDS-polyacrylamide gel electrophoresis showed a single band, and the MW was approximately 30.5kDa (Soyut et al., 2008, 2012; Soyut and Beydemir, 2008, 2012; Kaya et al., 2013). The kinetic and characteristic properties of CA such as the optimum pH, stable pH, optimum temperature, activation energy (Ea), activation enthalpy (δH), Q10, Km and Vmax were determined. Cadmium (Cd2+), copper (Cu2+), nickel (Ni2+) and silver (Ag+) inhibited CA activity in in vitro conditions. Ki values were calculated for these metals. Ki values were 31.20mM for cadmium (Cd2+), 161.96mM for copper (Cu2+), 10.79mM for nickel (Ni2+) and 0.0082mM for silver (Ag+) based on Lineweaver-Burk plots. Except for cadmium, heavy metals had the same inhibition mechanism. Cadmium was competitive, and the others were noncompetitive.
AtıfScopus17WoS16OpenAlex19İncele - MakaleAçık Erişim2015Scopus SJRQ2The production of ice cream using stevia as a sweetener
Ozdemir, C.; Arslaner, A.; Ozdemir, S.; Allahyari, M.
In this research, the effect of stevia addition on the physical, chemical and sensory properties of ice-creams were investigated. For this aim, four different ice- cream samples were produced using sucrose and stevia as sweetener (the plain + sucrose, cocoa + sucrose, plain + stevia and cocoa + stevia). The highest overrun ratio (20.17 %) was found in samples added cocoa and stevia. The viscosity of samples added cocoa and stevia (20.29 Pa.s) at 20 rpm were higher than that of other samples. The longest first melting time (3460 s) was found in samples added cocoa + stevia and the shortest time (1400s) was samples containing cocoa + sucrose. The last melting times were changed at around 8700 s and 9440 s. The pH degrees of samples were around 6.50 and 6.62. As samples containing stevia did not contain sucrose, sucrose amount of samples added sucrose were around 3.93 and 4.31 %. The fat destabilizations of samples were around 44.79 and 59.98 %. Panelists preferred the samples added stevia and cocoa as others.
AtıfScopus42WoS26OpenAlex54İncele - MakaleAçık Erişim2015Scopus SJRQ1Effect of in situ exopolysaccharide production on physicochemical, rheological, sensory, and microstructural properties of the yogurt drink ayran: An optimization study based on fermentation kinetics
Yilmaz, M.T.; Dertli, E.; Toker, O.S.; Tatlisu, N.B.; Sagdic, O.; Arici, M.
Exopolysaccharide (EPS)-producing starter cultures are preferred for the manufacture of fermented milk products to improve rheological and technological properties. However, no clear correlation exists between EPS production and the rheological and technological properties of fermented milk products such as the yogurt drink ayran. In this study, 4 different strain conditions (EPS- and EPS+ Streptococcus thermophilus strains) were tested as a function of incubation temperature (32, 37, or 42°C) and time (2, 3, or 4 h) to determine the effect of culture type and in situ EPS production on physicochemical, rheological, sensory, and microstructural properties of ayran. Furthermore, we assessed the effect of fermentation conditions on amounts of EPS production by different EPS-producing strains during ayran production. A multifactorial design of response surface methodology was used to model linear, interaction, and quadratic effects of these variables on steady shear rheological properties of ayran samples and in situ EPS production levels. The physicochemical and microbiological characteristics of ayran samples altered depending on incubation conditions and strain selection. Steady shear tests showed that ayran samples inoculated with EPS+ strains exhibited pseudoplastic flow behavior. Production of ayran with EPS- strain (control sample) resulted in the lowest apparent viscosity values (η50), whereas those produced with the combination of 2 EPS+ strains yielded ayran with notably increased η50 values. We concluded that incubation time was the variable with the greatest effect on η50, consistency coefficient (K), and flow behavior index (n) values. In situ EPS production was also affected by these conditions during ayran fermentation in which strain-specific metabolism conditions were found to be the most important factor for EPS production. In addition, these findings correlated the amount of in situ EPS produced with the rheological properties of ayran. Scanning electron microscopy images of the samples showed differences in structural features, revealing a prominent network strand structure in the ayran samples inoculated with the admixture of 2 EPS-producing strains incubated at 37°C for 3 h. These results provide useful information for large-scale production of ayran by the dairy industry.
AtıfScopus79WoS65OpenAlex92İncele - MakaleYalnız künye2017Scopus SJRQ3Performance analyses of gas turbine cogeneration plants
Karaali, Rabi; Oztürk, Ilhan Tekin
In this study, some improving methods of gas turbine cogeneration cycles are applied on a simple cogeneration cycle. These methods are preheating air, preheating air and fuel, inlet air cooling by using evaporative cooling and absorption cooling. These cogeneration systems are evaluated with respect to energy efficiency (energy utilization factor), exergetic efficiency, electric and heat power, electric-heat energy rate, artificial thermal efficiency and fuel energy saving ratio and are compared with each other. In these analyses, the thermodynamic parameters such as compressing ratio, air and fuel mass ratio and compressor inlet temperatures of the cycles are used. It is concluded that these parameters can be listed from most effective to least effective as air fuel ratio, pressure ratio and compressor inlet temperature. It is also concluded that the most efficient cycle is found to be the air-fuel preheated cycle for obtaining more electric power and less heat power, and the simple cycle is the most suitable one for obtaining more heat power and less electric power.
AtıfScopus6İncele - MakaleAçık Erişim2018Scopus SJRQ2The effect of apple cider vinegar and mushroom stalk supplementation on laying hens
Karaalp, Musa; Aksakal, Vecihi; Sarikaya, Sevim Beyza Ozturk; Urusan, Hilal; Bayram, Bahri; Zulkadir, Ayhan
The aim of this trial was to study the effects of consuming water with apple cider vinegar (ACV) and feed including mushroom (Agaricus bisporus) stalk (MS) on performance and certain egg characteristics. The hens were separated into four treatment groups (with 4 replicates and 6 hens per replicate). The experimental groups were control (not consumed ACV and MS), ACV (3 ml/l drinking water), MS (20 g/kg feed) and ACV+MS (combination). At the end of the experiment, among the performance criteria tested, body weight, feed intake, egg production and weight of eggs, and feed efficiency were not affected by the treatments (P>0.05). Treatments had no effect on physical external and internal egg characteristics. The amount of yolk malondialdehyde of the ACV and MS groups was lower than the control group (P<0.05) in stored eggs (28 d) (P<0.05).
AtıfScopus6WoS4OpenAlex7İncele - MakaleAçık Erişim2019Scopus SJRQ2Physicochemical characterisation of an α-glucan from Lactobacillus reuteri E81 as a potential exopolysaccharide suitable for food applications
İspirli, Hümeyra; Sagdic, Osman; Yılmaz, Mustafa Tahsin; Dertli, Enes
Lactobacillus reuteri strain (E81) is an alpha glucan producer from traditional sourdough and the physicochemical characteristics of this glucan was determined in this study. The HPLC analysis confirmed the presence of glucose as the only sugar monomer in the repeating structure of this exopolysaccharide (EPS). The functional groups within the glucan structure was detected by FTIR analysis. The scanning electron microscopy (SEM) analysis demonstrated the web-like branched structure of the glucan. Morphological characterisation of the glucan E81 by atomic force microscopy (AFM) analysis showed clear roundness lumps and chains. Importantly, thermal characteristics of glucan E81 determined by thermogram analysis (TGA) and differential scanning calorimeter (DSC) analysis revealed that glucan E81 has a melting point of 290 °C making it promising to be used in thermal processed foods including sourdough bread.
AtıfScopus77WoS71OpenAlex77İncele - MakaleAçık Erişim2015Scopus SJRQ2Characterization of a fast grown GaAs:Sn thin film by thermionic vacuum arc
Özen, Soner; Şenay, Volkan; Pat, Suat; Korkmaz, Şadan
In this research, a tin doped gallium arsenide thin film was grown on a glass substrate by means of the TVA technique in a very short period of time (70 s) and it’s morphological, compositional, and optical properties were examined. The deposited GaAs:Sn structures were characterized via both atomic force microscope (AFM) and field emission scanning electron microscope (FESEM). In this context, current research aims to reach a conclusion about the structure of the produced GaAs:Sn film by combining AFM, FESEM and energy dispersive X-ray spectroscopy data. From the optical investigation, the refractive index and extinction coefficient values for the produced film were obtained as 3.68 and 0.03 at the wavelength of 632.8 nm, respectively. The direct optical band gap energy of the deposited thin film was determined by two different models. Estimated optical band gap values were compared with each other. The results showed that TVA technique is suitable for a GaAs:Sn coating on glass substrate.
AtıfScopus6WoS5OpenAlex6İncele - MakaleAçık Erişim2016Scopus SJRQ1Electrorheological Fluids Equations Involving Variable Exponent with Dependence on the Gradient via Mountain Pass Techniques
Mashiyev, R. Ayazoglu; Ekincioglu, Ismail
This article deals with a quasilinear elliptic equation with variable exponent under a homogenous Dirichlet boundary-value condition, where nonlinearity also depends on the gradient of the solution. By using an iterative method based on Mountain Pass techniques, the existence of a positive solution is obtained.
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