Yazarlar
- Dertli, Enes(8)
- Şahin, Engin(6)
- Serencam, Hüseyin(3)
- Şenay, Volkan(3)
- Abdioglu, M.(2)
- Bayram, Ozkan(2)
- Bolat, Fevzi Cakmak(2)
- Celik, S.(2)
- Ecem Bayram, Nesrin(2)
- Guner, S.B.(2)
- Gökçe, H. Süleyman(2)
- Ozturk, K.(2)
- Tekce, E.(2)
- Yilmaz, Mustafa Tahsin(2)
- Özen, Soner(2)
- Şahin, Rıdvan(2)
- 'Yilmaz, Mustafa Tahsin(1)
- Agirman Aydin, Tuba(1)
- Akay, Ebru Çağlayan(1)
- Akgül, Halil İbrahim(1)
- Akkoyunlu, Ebubekir(1)
- Akkus, B.(1)
- Altunişik, Ahmet Can(1)
- Alım, Bünyamin(1)
- Andiç-Çakır, Özge(1)
- Arici, Muhammet(1)
- Artar, Musa(1)
- Atalan, Abdulkadir(1)
- Ates, Ibrahim(1)
- Ateş, Şevket(1)
- Ayazoglu, Rabil(1)
- Aydoğmuş, Tuna(1)
- Bakali, Assia(1)
- Baltas, Niniet(1)
- Basaran, S.(1)
- Bayrakceken, Abdulkadir(1)
- Bayraktar, Bülent(1)
- Bayraktar, M. Kilic(1)
- Bayram, Nesrin Ecem(1)
- Bayram, Sinan(1)
Yayınlar
- MakaleÖn baskısı açık2019Piezoelectric and electromagnetic hybrid energy harvesting with low-frequency vibrations of an aerodynamic profile under the air effect
Bolat, Fevzi Cakmak; Basaran, S.; Sivrioglu, S.
In this study, a novel hybrid energy harvesting system consisting of a piezoelectric material and an electromagnetic induction device is experimentally inevstigated. Flow-induced vibrations can be considered as an aerodynamics air effect and can be converted to electrical energy. By connecting an airfoil profile to a beam element, vibrations are occurred on the proposed structure by creating an aerodynamic air effect. This aerodynamic air effect is controlled by using an Arduino board with a solenoid valve connected to the air line. A piezoelectric transduction is attached on the beam, and an electromagnetic-Lorentz induction is connected to the airfoil element at the end of this beam. Energy is simultaneously harvested by using electromagnetic induction and piezoelectric transduction with respect to the vibration motion of the beam. Within the scope of the study, the amount of energy obtained using the piezoelectric material and Lorentz actuator by connecting resistors of different sizes are measured with an oscilloscope. The experimental results show that the amount of energy obtained from the proposed structure is at promising levels that can be used to run small electronic units which commonly used in aerospace applications.
AtıfScopus60WoS51
İncele - MakaleYalnız künye2019Biocatalyzed Enantiomerically Pure Production of (S)-Phenyl(thiophen-2-yl)methanol
Şahin, Engin; Dertli, Enes
Chiral aryl heteroaryl methanols are important precursors for the synthesis of pharmaceutically important molecules. The aims of this study were to use a biocatalyst that could efficiently bioreduce phenyl(thiophen2- yl) methanone 1 to (S)-phenyl(thiophen-2-yl) methanol 2, to identify the impact of the physicochemical factors that might affect the bioreduction by the biocatalyst, and to obtain multigram production of aryl heteroaryl secondary alcohol 2 with the biocatalyst under optimized conditions. Over the years, the (S)phenyl( thiophen-2-yl) methanol was synthesized on a small scale using a chemical catalyst without its enantiomerically pure form. In this study, Lactobacillus paracasei BD101 was used for the asymmetric reduction of phenyl(thiophen-2-yl) methanone to (S)-phenyl(thiophen-2-yl) methanol in the large-scale production. The asymmetric bioreduction conditions were systematically optimized, and the production of 3.77 g of (S)-phenyl(thiophen-2-yl) methanol was carried out in enantiomerically pure form > 99% enantiomeric excess (ee), > 99% conversion, and 90% yield. This method obtained with this biocatalyst is a process that can be used industrially in terms of conversion, ee, and yield. This study provides guidance for the application of L. paracasei BD101 in the production of optically active aryl heteroaryl alcohols.
AtıfScopus12WoS12İncele - MakaleYalnız künye2019Partial characterization of a levan type exopolysaccharide (EPS) produced by Leuconostoc mesenteroides showing immunostimulatory and antioxidant activities
Taylan, Osman; Yilmaz, Mustafa Tahsin; Dertli, Enes
Leuconostoc mesenteroides S81 was isolated from traditional sourdough as an exopolysaccharide (EPS) producer strain. The monosaccharide composition of the EPS from strain S81 was characterized by HPLC analysis and only fructose was found in the repeating unit structure. The NMR spectroscopy analysis revealed that EPS was a levan type EPS as a β-(2 → 6)-linked fructan. The FTIR analysis further confirmed the presence of the furanoid rings in the EPS structure. The levan S81 showed high level of thermal stability determined by DSC and TGA analysis. The lyophilised levan S81 showed a sheet-like compact morphology and its aqueous solution formed spheroidal lumps with a compact structure detected by SEM and AFM analysis, respectively. Importantly the levan S81 showed a high level of immunomodulatory role, induced the anti-inflammatory cytokine IL-4, and exhibited a strong antioxidant capacity with EC50 value 1.7 mg mL−1 obtained by hydroxyl radical scavenging activity test under in vitro conditions. These findings reveal potential of levan S81 for technological purposes and as a potential natural immunomodulatory and antioxidant.
AtıfScopus132WoS112
İncele - MakaleYayıncıda açık erişim2019Articles on biotechnology teaching: Thematic content analysis study
Toman, Ufuk
This thematic content analysis done about teaching biotechnology which is researched in Turkey is conducted with 64 articles, from a total of 45 magazines published in Turkey from 2003 to 2018. An analysis of the research trends of Turkish researchers based on teaching biotechnology. In this research, it has been tried to guide the researchers by determining the trends in the field and research methods frequently used(changes according to publication years and languages, what kind of research problems on qualitative research subjects are emphasised, what research methods are used, data collection tools, sample or working group, data analysis methods). In studies conducted to investigate the biotechnology education in Turkey, it shows that there is not adequate studies to address the issue of biotechnology education. Biotechnology and its sub-rules, cloning, genetically modified organisms, biotechnological vaccines, genetic engineering and microbiology may require more space in curricula at early learning levels.
AtıfScopus7İncele - MakaleYalnız künye2019Integrated QFD, fuzzy linear regression and ZOGP: An application of e-store design
Celik, Pelin; Ustasuleyman, Talha
In the current, highly competitive marketplace, customer demand is a major factor in the product design process. Most firms make an effort to indicate that their products differ from the competitors’ products. The purpose of this paper is to understand customers’ expectations of and technical requirements for e-stores and to evaluate most popular e-stores in Turkey (i.e., ES1, ES2, ES3). In this study, the authors aim to understand the customer expectations and technical requirements by using quality function deployment (QFD). To prepare the house of quality (HoQ), the authors surveyed 20 experts who are customers who have elite membership (their expenses for these e-stores are more than regular customers and have elite cards) of the three e-stores and academicians. After creating the HoQ, the authors employ fuzzy linear regression to evaluate the relationships between customer expectations and technical requirements and among technical requirements themselves. Finally, the authors use zero-one goal programming (ZOGP) to select the most desirable e-store.
AtıfScopus1WoS1İncele - MakaleYayıncıda açık erişim2019Impact of heat treatment and acid gelation on polyphenol enriched milk samples
Bayraktar, M. Kilic; Harbourne, N.B.; Fagan, C.C.
The effects of heat treatment and the stage of polyphenol addition to milk before or after heat treatment on the total phenolic content (TPC), ferric-ion reducing antioxidant power (FRAP), pH, casein micelle size (CMS) and whey protein denaturation content of milk-polyphenol mixtures were investigated. Four sources of phenolic compounds (green tea, white grape, tannic acid, gallic acid) were incorporated into pasteurized-skim milk. A heat treatment (85 °C for 30 min) was applied to pasteurized-skim milk either before (MhP) or after polyphenols addition (MhPh). Acid milk gels were produced using MhPh samples, and their TPC and FRAP were determined. Heat treatment decreased the TPC and FRAP values of the samples, except for tannic acid, probably due to increased polyphenol-protein interactions. However, MhPh tannic acid sample resulted in significantly higher FRAP value than MhP. The addition of gallic acid before heat treatment (MhPh) significantly increased CMS due to the lower pH of this sample during heating. Acid gelation decreased the extractable polyphenols, however there was no significant different on FRAP between acid gel and MhPh milk samples. This study showed that the properties of phenolic source, particularly pH, and the stage of polyphenol addition to milk had an impact on selected properties.
AtıfScopus25WoS23İncele - MakaleYalnız künye2019Comparative study of hot and cold press and their effect on superconducting properties of coronene added bulk MgB2
Erdem, O.
In this study, the superconducting properties of 4 wt% coronene (C24H12) added polycrystalline bulk MgB2 samples prepared by hot pressing and cold pressing, were reported in detail. The results were compared to determine one of which pressing methods is more useful to substitute of carbon released from C24H12 into MgB2 structure and to increase the superconducting properties of MgB2. The lattice strain, crystallite size, residual resistivity, superconducting transition temperature (Tc), critical current density (Jc), flux pinning force density (Fp) and vertical/lateral levitation force (Fz, Fx) were analysed for the hot and cold pressed samples. The a-lattice parameter and Tc value reduced sharply for 4 wt% C24H12 added cold pressed sample, resulting in a notable decrease of increment ratio of Jc and Fp values, while the depressing of Tc is lower for 4 wt% C24H12 added hot pressed sample. The cold pressing strongly increased the lattice strain, confirming more C substitution, while the hot pressing ensured smaller crystallite size. The Jc and Fp values were respectively found as 4.6 × 103 A/cm2, 1.3 × 104 A/cm2, 5.8 × 103 A/cm2 and 1.8 × 108 N/m3, 5.1 × 108 N/m3, 2.3 × 108 N/m3 for the pure sample and, 4 wt% C24H12 added hot and cold pressed samples at 20 K, 4 T. The maximum repulsive and attractive levitation force values at 20 K in ZFC and FC regimes were obtained for the 4 wt% C24H12 added hot pressed sample. Finally, the hot pressing provides an effective way to substitute C into MgB2 lattice without a remarkable decrease of Tc value, ensuring more homogenous and compacted structure, more electron–phonon interaction and strong flux pinning force.
AtıfScopus6WoS6İncele - MakaleÖn baskısı açık2019Green synthesis of enantiopure (S)-1-(benzofuran-2-yl)ethanol by whole-cell biocatalyst
Şahin, Engin
Optically active aromatic alcohols are valuable chiral building blocks of many natural products and chiral drugs. Lactobacillus paracasei BD87E6, which was isolated from a cereal-based fermented beverage, was shown as a biocatalyst for the bioreduction of 1-(benzofuran-2-yl) ethanone to (S)-1-(benzofuran-2-yl) ethanol with highly stereoselectivity. The bioreduction conditions were optimized using L. paracasei BD87E6 to obtain high enantiomeric excess (ee) and conversion. After optimization of the bioreduction conditions, it was shown that the bioreduction of 1-(benzofuran-2-yl)ethanone was performed in mild reaction conditions. The asymmetric bioreduction of the 1-(benzofuran-2-yl)ethanone had reached 92% yield with ee of higher than 99.9% at 6.73 g of substrate. Our study gave the first example for enantiopure production of (S)-1-(benzofuran-2-yl)ethanol by a biological green method. This process is also scalable and has potential in application. In this study, a basic and novel whole-cell mediated biocatalytic method was performed for the enantiopure production of (S)-1-(benzofuran-2-yl)ethanol in the aqueous medium, which empowered the synthesis of a precious chiral intermediary process to be converted into a sophisticated molecule for drug production.
AtıfScopus32WoS30İncele - MakaleYalnız künye2019Modification of eutectic Al-Si alloys by Sr and CuSn5
Çolak, Murat
Enhanced properties can be achieved in Al-Si alloys by several alloying element additions. Typical modifiers are Na, Sr, and Sb that alters Si into a fibrous structure. Fluidity and mechanical properties increase as well as machinability can be improved. In this work, eutectic Al-Si alloy was modified with Al10Sr, CuSn5, and Al10Sr + CuSn5 master alloys. Microstructural characterization was carried out by optical and scanning electron microscopy. Density and hardness of the samples were measured. Wear tests were carried out. It was found that Sr modified Al12Si revealed better performance than CuSn modified.
AtıfScopus21WoS19İncele - MakaleYayıncıda açık erişim2019Production of skim milk powder by spray-drying from transglutaminase treated milk concentrates: Effects on physicochemical, powder flow, thermal and microstructural characteristics
Er, Betül; Sert, Durmuş; Mercan, Emin
The effects of transglutaminase (TGase) treatment of skim milk concentrates on physicochemical, powder flow, thermal, microstructural characteristics and protein profiles of skim milk powders (SMP) were investigated. Spray-dried SMP samples produced from milk concentrates were TGase-treated at enzyme concentrations of 0 (control), 0.020% (TG-20), 0.030% (TG-30) and 0.035% (TG-35). Lower particle size values were observed in TGase-treated samples. TGase treatment slightly decreased zeta potential and increased the a* value (redness) of SMPs. Up to a concentration of 0.030%, TGase treatment decreased caking characteristics and increased glass transition temperatures of samples. The TGase treatment above 0.035% significantly decreased cohesion index and compaction coefficient at different speeds. TG-35 showed free flowing flow behaviour depending on the cohesion index, whereas control, TG-20, and TG-30 showed easy flowing behaviour. SDS-PAGE analysis revealed that high molecular mass bands indicated cross-linking in TGase-treated milk powders.
AtıfScopus30WoS24İncele - EditoryalYalnız künye2019Preface
Akay, Ebru Çağlayan; Korkmaz, Özge
- MakaleYalnız künye2019Production of enantiomerically pure (S)-phenyl(pyridin-2-yl)methanol with Lactobacillus paracasei BD101
Şahin, Engin; Serencam, Hüseyin; Dertli, Enes
Asymmetric reduction studies of heteroaryl ketones, including phenyl(pyridin-2-yl)methanone in enantioselective form with biocatalysts are very few, and chiral heteroaryl alcohols have been synthesized generally in the small scale. In this study, seven bacterial strains have been used to produce the (S)-phenyl(pyridin-2-yl)methanol in high enantiomeric excess and yield. Among the tested strains, Lactobacillus paracasei BD101, was found to be the best biocatalyst for the reducing phenyl(pyridin-2-yl)methanone to the (S)-phenyl(pyridin-2-yl)methanol at gram scale. The asymmetric bioreduction conditions were systematically optimized using L. paracasei BD101, which demonstrated excellent enantioselectivity and high level of conversion for the bioreduction reaction. (S)-phenyl(pyridin-2-yl)methanol, which is an analgesic, was produced enantiomerically pure form in the first time on gram scale using a biocatalyst. In total, 5.857 g of (S)-phenyl(pyridin-2-yl)methanol in enantiomerically pure form (>99% enantiomeric excess) was obtained in 52 h with 93% yield using whole cells of L. paracasei BD101. Enantiomerically pure (S)-phenyl (pyridin-2-yl)methanol, which is an analgesic, was first produced in the gram scale using a biocatalyst with excellent ee (>99%) and yield (93%).
AtıfScopus9WoS7İncele - MakaleYalnız künye2019Response surface optimization for a nonlinearly constrained irregular experimental design space
Ozdemir, Akin; Cho, Byung Rae
Finding optimum conditions for process factors in an engineering optimization problem with response surface functions requires structured data collection using experimental design. When the experimental design space is constrained owing to external factors, its design space may form an asymmetrical and irregular shape and thus standard experimental design methods become ineffective. Computer-generated optimal designs, such as D-optimal designs, provide alternatives. While several iterative exchange algorithms for D-optimal designs are available for a linearly constrained irregular design space, it has not been clearly understood how D-optimal design points need to be generated when the design space is nonlinearly constrained and how response surface models are optimized. This article proposes an algorithm for generating the D-optimal design points that satisfy both feasibility and optimality conditions by using piecewise linear functions on the design space. The D-optimality-based response surface design models are proposed and optimization procedures are then analysed.
AtıfScopus18WoS13İncele - BildiriYalnız künye2019Tracking particle near a flat surface in digital video microscopy
Yücel, Harun; Akkus, B.; Cakirli Mutlu, R.B.; Gudekli, E.; Kinaci, B.; Guzelcimen, F.; Susoy Dogan, G.; Ozturk, F.C.; Ertoprak, A.
Digital video microscopy (DVM) is an important tool to obtain quantitative information about underlying physics in colloidal systems. DVM, however, has the overlap problem caused by particle's diffraction pattern when the detected particles are close to contact. This overlapping problem limits the tracking methods in determining accurate particle position that reflects all interactions exerting to particles or objects in colloidal studies. The problem occurs not only between two spherical particles close to each other but also when a spherical particle is close to a rod shaped particle which have a flat surface. In this study, the simulation results on the tracking spherical particle placed near the flat surface of a rod particle in 2D digital video microscopy are reported. This work shows that the overlap problem can be resolved by using a fraction of the intensity distribution of a spherical particle which is close to a flat surface.
- Kitap BölümüYalnız künye2019A panel causality analysis on countries attracting most tourists on the basis of carbon emissions, renewable energy, tourism revenues, and trade openness
Boz, Füsun Çelebi
- MakaleYayıncıda açık erişim2019Effective reduction of graphene oxide using sulfur dioxide-containing chemical compounds
Korucu, H.; Şimşek, B.; Kocakerim, M.M.; Karakaş, I.H.
The success of the graphene oxide reduction process depends on how similar the product is to pristine graphene. Sulfur oxide, which is a significant industrial waste gas, can be used in the reduction of graphene oxide. In this study, the graphene oxide reduction process was performed by using sulfur oxide with sodium tetraborate decahydrate, l-ascorbic acid, ammonium hydroxide, sodium hydroxide, lithium hydroxide, sodium borohydride and sodium thiosulfate. The carbon-to-oxygen atomic ratio and D-to-G peak ratio of the graphene oxide, which represent the degree of reduction, were 2.64–4 and 0.78–1.80 with the use of sulfur oxide, respectively. The sulfur oxide/sodium borohydride mixture increased the carbon-to-oxygen atomic ratio of the graphene oxide to 11.73, while improving the value of the D-to-G peak ratio at 3.14. The reduced graphene oxide with the highest specific heat capacity was obtained using sodium tetraborate decahydrate, with an improvement of 74.54% compared to graphene oxide. The results show that sulfur oxide, which is harmful to the environment and human health, can be utilized in an effective reduction process, together with other reducing chemicals, to obtain an industrially valuable material, such as reduced graphene oxide.
AtıfScopus15WoS14İncele - MakaleYalnız künye2019Optical and surface properties of ZnN thin films manufactured by radio frequency reactive magnetron sputtering
Şenay, Volkan; Özen, Soner; Aydoğmuş, Tuna
ZnN is a relatively new material and its physical properties are not yet well studied. In this research, ZnN thin films having different thickness values were deposited on glass substrates by means of radio frequency (RF) reactive magnetron sputtering technique at room temperature and some physical properties of ZnN thin films were investigated by several techniques. UV–vis spectrophotometer and reflectometer were employed to investigate the optical properties of the produced thin films. The surface properties were investigated by using tensiometer and atomic force microscope (AFM). The effects of film thickness on the optical and surface properties of ZnN thin films were discussed. The refractive index and band gap values were found to be dependent on thickness of ZnN thin films. The AFM investigations indicated that the surfaces of the films are compact and smooth. From the wetting experiments, it was found that the surfaces of the films are hydrophobic and surface free energy values are low as reported in literature.
AtıfScopus5WoS5İncele - MakaleYalnız künye2019Synthesis and Biological Evaluation of Novel Tricyclic Pyrrolidinyl (R)-Alcohols and Amines
Şahin, Engin; Kılıç, Hamdullah; Törnük, Fatih; Dertli, Enes
Three new tricyclic pyrrolidinyl alcohols and three tricyclic pyrrolidinyl amines were synthesized, and the antibacterial activities of these compounds were tested against Salmonella enterica subsp. enterica serovar Typhimurium, Escherichia coli O157:H7, Staphylococcus aureus, and Listeria monocytogenes. All tested pyrrolidinyl alcohols and amines showed antibacterial activity to the tested pathogens, but this activity was dependent on the final concentration of the tested compound, and the structure of these compounds were also important for this antibacterial activity. Of the tested compounds, (2R)-2-(octahydro-4,8-ethanocyclohepta[c] pyrrol2(1H)-yl)-2-phenylethanamine (2c) was the most effective compound among the tested pyrrolidinyl alcohols and amines. This study shows a good example of finding new antimicrobials in order to control pathogenic bacteria.
AtıfScopus1WoS1İncele - MakaleYalnız künye2019Impact of Managers’ Innovation Perception on Innovation Activities and Innovation Strategies in Hotel Businesses
Karakaş, Ayhan; Bilgin, Yusuf; Yildiz, Muhammed Raşit
The purpose of this study is to examine the impact of managers’ innovation perceptions on innovation activities and innovation strategies in hotel business. The research also examined the relationship between innovation types applied in hotel businesses and innovation strategies. Quantitative method was used in the research. The universe of the research constitutes hotel businesses operating in the Western Black Sea Region. Survey data were obtained using questionnaire technique. As a result of the analysis, it is determined that the innovation perceptions of the managers of the hotel businesses has an effect on the types of innovations applied in the businesses. Nevertheless, it has been determined that business managers’ perceptions of innovation have no meaningful effect on innovation strategies applied to the business. In other words, it has been reached that the innovation strategies of the businesses are determined by the variables other than the innovation perceptions of the managers. The research also find that there is a relationship between innovation types applied in hotel businesses and innovation strategies.
AtıfScopus2İncele - MakaleYalnız künye2019Optimization of design parameters for heat transfer and friction factor in a heat sink with hollow trapezoidal baffles
Sahin, Bayram; Ates, Ibrahim; Manay, Eyuphan; Bayrakceken, Abdulkadir; Celik, Cafer
The aim of this study is to optimize the design parameters of a heat sink on which hollow trapezoidal baffles are mounted on the bottom surface by using Taguchi experimental-design method. The Nusselt number and the friction factor are considered as performance parameters. An orthogonal array is selected as experimental plan for the six parameters: the corner angle (α), the inclination angle (β), the baffle height (H), the baffle length (L), the baffle width (S) and Reynolds number. First of all, each goal has been optimized, separately. Then, all the goals have been optimized together, considering the priority of the goals. The length of the baffle is found to be the most influential parameter on the friction factor. This can be attributed the enhanced effect of longitudinal vortices with baffle length in flow direction. Likewise, it is demonstrated that the most effective parameter on the heat transfer is Reynolds number. The results show that the baffle width (S) and the corner angle (α) have insignificant effect on Nusselt number. The maximum heat transfer was obtained at Re = 17,000, H = 36 mm, L = 45 mm, S = 26 mm, α = 0°, β = 0°. The inclination angle (β) and the baffle height (H) have nearly no effect on the friction factor. The minimum friction factor was obtained at Re = 17,000, H = 20 mm, L = 25 mm, S = 26 mm, α = 16°, β = 0°. The inclination angle (β) and the baffle height (H) have nearly no effect on the friction factor. It can be concluded that the higher heat transfer rates can be achieved with lower pressure drop penalty with this type of vortex generator in particular configurations.
AtıfScopus31WoS27İncele