Sürdürülebilir Kalkınma Amaçları
Yazarlar
- Dertli, Enes(11)
- Hasar, Ugur Cem(8)
- Kaya, Yunus(8)
- Özdemir, Akın(7)
- İspirli, Hümeyra(7)
- Şahin, Engin(7)
- Ertugrul, Mehmet(6)
- Yilmaz, Mustafa Tahsin(6)
- Abdioglu, Murat(4)
- Ozturk, Gokhan(4)
- Ozturk, Hamdullah(4)
- Uçurum, Metin(4)
- Abdioglu, M.(3)
- Cinar, Mehmet(3)
- Ozturk, K.(3)
- Ozturk, U. Kemal(3)
- Taylan, Osman(3)
- Asiri, Abdullah M.(2)
- Banaz, Emrullah(2)
- Bekir, Seyhan(2)
- Beydemir, Şükrü(2)
- Bulbuloglu, Semra(2)
- Can, Zehra(2)
- Can, Özgür Devrim(2)
- Chinna Babu, P.(2)
- Cinar, M.(2)
- Gökçe, H.S.(2)
- Izginli, Mucahit(2)
- Karabacak, M.(2)
- Karabacak, Mehmet(2)
- Korkmaz, Kader(2)
- Kurt, M.(2)
- Makas, Samet(2)
- Manci, Egemen(2)
- Okumus, Halil Ibrahim(2)
- Ozkat, Erkan Caner(2)
- Saricaoglu, Furkan Turker(2)
- Sağdıç, Osman(2)
- Sundaraganesan, N.(2)
- Söyüt, Hakan(2)
Yayınlar
- MakaleAçık Erişim2021Scopus SJRQ1New formalism for characterization of simple non-reciprocal networks free from singularity-point problem
Hasar, Ugur Cem; Kaya, Yunus; Ozturk, Gokhan; Ozturk, Hamdullah; Izginli, Mucahit; Ertugrul, Mehmet
A method has been proposed for accurate characterization of non-reciprocal networks without enforcing the passivity principle. Thanks to the introduced different even and odd coefficients, our method has no singularity-point problem as compared with the conventional method. The proposed method is validated by scattering parameter measurements of a ferrite-loaded waveguide shifter. In addition, it is demonstrated by measurements that our method, as compared with the conventional one, is more resistant to random noise due to post-calibration effects.
AtıfScopus1WoS1OpenAlex1
İncele - MakaleYalnız künye2020Scopus SJRQ1Structural and physicochemical characterisation and antioxidant activity of an α-D-glucan produced by sourdough isolate Weissella cibaria MED17
Aburas, Hani; İspirli, Hümeyra; Taylan, Osman; Yilmaz, Mustafa Tahsin; Dertli, Enes
An exopolysaccharide (EPS) producer slimy-mucoid type colony was isolated from sourdough and identified as Weissella cibaria MED17. The 1H and 13C NMR spectra of EPS MED17 demonstrated that this EPS was a dextran type glucan ((1 → 6)-linked α-D-glucose core structure) containing (1 → 3)-linked α-D-glucose branches and proportion of (1 → 6)-linked α-D-glucose units to (1 → 3)-linked α-D-glucose units was 94.3:5.7%. The FTIR analysis also confirmed the (1 → 6)-linked α-D-glucose linkage. A high level of thermal stability was observed for glucan MED17 as no degradation up to 300 °C was observed by TGA and DSC analysis. The XRD analysis of glucan MED17 showed its semi- crystalline nature and its compact sheet-like morphology was observed by SEM analysis. Finally, antioxidant characteristics of glucan MED17 were determined by ABTS and DPPH radical scavenging activity tests that revealed a moderate antioxidant activity of glucan MED17. These findings show potential techno-functional characteristics of glucan MED17.
AtıfScopus58WoS55OpenAlex59
İncele - MakaleAçık Erişim2020Scopus SJRQ1Development of particle swarm and topology optimization-based modeling for mandibular distractor plates
Şensoy, Abdullah Tahir; Kaymaz, Irfan; Ertaş, Ümit
Mandibular Distraction Osteogenesis (MDO) is a common clinical procedure to correct mandibular retrognathia. However, since there is not a gold standard for determining the screw positions for current MDO operations, deviation of distraction direction and malocclusion increases. This case results in need of additional operations that affect the callus stability. In these cases, relapse risk increases and remodelling period gets longer. On the other hand, large volume of the distractor plates results in more invasive treatment and negatively affects the patients’ comfort. To overcome these problems, this study offers a new method including; virtual surgery simulation, determining the optimum screw configuration using particle swarm optimization loop linked between MATLAB-PYTHON-ANSYS programs and the design of distractor plate geometry with topology optimization. In order to test the proposed method, two different Finite Element (FE) models, CM and OM, were established based on conventional and optimum method, respectively. FEA results of the current study reveals that OM has 33.56% less displacement compared to CM, and the most critical screw in terms of screw loosening for OM has 35.29% less strain value than CM. These outcomes show OM shows superior callus stability in comparison with CM. On the other hand, redesign of the distractor plates using topology optimization according to the best screw positions provides 43.32% reduction in the total implant volume which means reduced cost and a less invasive MDO operation. Therefore, the clinical use of this protocol is expected to increase the success of the operation by shortening the recovery period.
AtıfScopus13WoS11OpenAlex13İncele - MakaleYalnız künye2020Scopus SJRQ1Azo dye-functionalized magnetic Fe3O4/polyacrylic acid nanoadsorbent for removal of lead (II) ions
Sadak, Omer; Hackney, Robert; Sundramoorthy, Ashok K.; Yilmaz, Galip; Gunasekaran, Sundaram
We report the fabrication of a nanoadsorbent for the removal of heavy metals. The nanoadsorbent is comprised of ferric oxide (Fe3O4) magnetic nanoparticles (MNPs) covalently conjugated with polyacrylic acid (PAA) and further functionalized with an azo dye (Congo red, CR) using carbodiimide. This Fe3O4 core and PAA-CR shell system (MNP/PAA-CR) exhibited binding affinity towards various cations (Pb2+, Fe2+, Fe3+, Cd2+, and Cu2+) at room temperature. Using MNP/PAA-CR we studied its heavy metal removal effectiveness and kinetics targeting Pb2+ under various reactions conditions including time and pH. The Pb2+ removal efficiency and adsorption capacity were maximal at pH 6.5 and 45 min of reaction time, and the Pb2+ adsorption kinetics better fit a pseudo second-order model than a first-order model. The adsorption of Pb2+ by MNP/PAA-CR was also investigated by the so-called Langmuir and Freundlich isotherms, and the Langmuir isotherm predicted a maximum absorption of 195.3 mg.g-1. Our results further indicated that MNP/PAA-CR is potentially reusable after desorption of the adsorbed metal with only small decline in adsorption ability over five consecutive cycles of regeneration.
AtıfScopus26OpenAlex17İncele - MakaleAçık Erişim2020Scopus SJRQ2Magnetic force and stiffness performances of Maglev system based on multi–surface arrangements with three-seeded bulk YBaCuO superconductors
Ozturk, K.; Abdioglu, M.; Karaahmet, Z.
We have designed a multi–surface HTS (high temperature superconductor with three seeded bulk YBaCuO) Maglev system by increasing the YBaCuO number while decreasing the PM number in HTS–PMG system to enhance the loading capacity and stability of the superconducting Maglev system while reducing the fabrication cost. By this study, a detailed investigation on the magnetic levitation force, guidance force, magnetic stiffness and cost analysis of the multi–surface HTS Maglev system has been carried out for the first time. In this study, it is determined that the multi–surface YBaCuO–PMG arrangements are superior to the single–surface arrangements with respect to the loading capacity and especially the movement stability of Maglev systems together. Additionally, it is seen that the using of the multi–surface YBaCuO–PMG arrangement reduces the fabrication cost of the Maglev systems as 42.0% for 1000 km magnetic rail while increasing of the levitation force efficiency as 43.4% and this emphasizes the advantage of multi–surface arrangements to the classical single–surface ones. The obtained results can contribute to the researchers working on Maglev and have a capability to increase the usage potential of Maglev systems in commercial applications because of both the loading capacity and stability of Maglev systems can be enhanced together with reducing the fabrication cost without any loss in levitation performance.
AtıfScopus19WoS18OpenAlex21İncele - MakaleAçık Erişim2020Scopus SJRQ1Investigation of ammonia stripping with a hydrodynamic cavitation reactor
Taşdemir, Atila; Cengiz, İbrahim; Yildiz, Ergün; Bayhan, Yalçın Kemal
Ammonia is a commonly used compound in the domestic and industrial fields. If ammonia found in wastewater after use is not treated, even at low concentrations it may cause toxic effects in the receiving environment. In this study, a hydrodynamic cavitation reactor (HDC) was designed with the aim of removing ammonia. The effect of parameters like different cavitation numbers, airflow, temperature and initial concentration on NH3 removal was researched. The potential of hydrodynamic cavitation for removal of volatile gases, like NH3, was assessed with the aid of two film theory mathematical equations. Experimental studies were performed at fixed pH = 11. Under the conditions of 0.12 cavitation number, 25 L/min airflow, 30 °C temperature and 2500 mg/L initial concentration, in 24 h 98.4% NH3 removal efficiency was achieved. With the same experimental conditions without any air, the HDC reactor provided 89.5% NH3 removal at the end of 24 h. The HDC reactor is very effective for the removal of volatile gases from wastewater and it was concluded that even in the absence of aeration, the desired NH3 removal efficiency was provided.
AtıfScopus31WoS27OpenAlex33İncele - MakaleAçık Erişim2020Scopus SJRQ1Propagation constant measurements of reflection-asymmetric and nonreciprocal microwave networks from S-parameters without using a reflective standard
Hasar, Ugur Cem; Kaya, Yunus; Ozturk, Gokhan; Ertugrul, Mehmet
We propose a simple method for determination of forward and backward propagation constants of nonreciprocal uniform networks or lines with asymmetric reflections. The wave cascading matrix presentation is used to diagonalize and decompose the line in terms of impedance and amplitude/phase transitions. The proposed method uses scattering parameters of the line/network connection and the thru connection, thus eliminating errors arising from fabrication tolerance and thickness of the second line. Besides, compared with conventional methods which necessitate calibration techniques such as the thru-reflect-line, our method has the advantage that it determines propagation constants without resorting the measurement of any reciprocal reflective standard. Propagation constant measurements of a reciprocal network (different-length X-band waveguide straights) and a nonreciprocal network (microwave phase shifter) were first carried out and then compared with those measured by different methods to validate and monitor the accuracy of our method.
AtıfScopus13WoS12OpenAlex11İncele - 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.
AtıfScopus43WoS40OpenAlex42İncele - MakaleAçık Erişim2019Scopus SJRQ2A study of gamma attenuation property of UHMWPE/Bi 2 O 3 nanocomposites
Abdalsalam, Alyaa H.; Sayyed, M.I.; Ali Hussein, Thulfiqar; Şakar, Erdem; Mhareb, M.H.A.; Ceviz Şakar, Betul; Alim, Bünyamin; Kaky, Kawa M.
In this study, nanocomposite material made of ultra-high molecular weight and bismuth oxide was developed to be used for protection from nuclear radiation. The traditional hot-pressing technique was used for preparing composite samples. The concentrations of Bi 2 O 3 were selected to be 0.5, 1.0, 1.5, 2.0 wt%. In order to study the changes in surface morphology, we examined all samples by scanning electron microscopic (SEM). We evaluated the semi-quantitative of all elements used to fabricate these samples using EDX. Additionally, all samples including pure Bi 2 O 3 has been examined with X-ray diffraction (XRD). Besides that, Raman spectroscopy of all synthesized polymer matrix was measured to explore the different molecular groups. Also, the photon attenuation ability for the present samples was measured experimentally at eight energies varying from 30.8 keV to 383.9 keV using 133 Ba radioactive point source.
AtıfScopus68WoS64OpenAlex70İncele - MakaleYalnız künye2019Scopus SJRQ1Partial 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.
AtıfScopus132WoS112OpenAlex126İncele - MakaleYalnız künye2019Scopus SJRQ2Comparative 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.
AtıfScopus6WoS6OpenAlex6İncele - MakaleAçık Erişim2019Scopus SJRQ1A method for active seismic earth thrusts of granular backfill acting on cantilever retaining walls
Kamiloğlu, Hakan Alper; Şadoğlu, Erol
The failure mechanism plays an important role in the active seismic earth thrusts acting on cantilever retaining walls. Cantilever retaining walls can be classified as having a long heel or a short heel based on the intersection between the stem of the retaining wall and the failure surface. In the literature, different seismic earth thrust calculation methods have been suggested considering the long heel or the short heel cases. However, no unique study has been done that is applicable to walls with either a long heel or a short heel. The aim of this study is to suggest a new active seismic earth thrust calculation method for granular soils which is applicable to retaining walls with either a short heel or a long heel using a pseudo-static approach. Three different earth thrusts are considered to be acting on three different parts of a wall backface. Each thrust is derived in terms of the parameters defining the wall geometry, the soil properties and the seismic activity. The thrust coefficients are determined by maximizing the sum of the horizontal components of the earth thrusts. An algorithm is developed and coded for this aim. The results of the suggested method are compared with those of other conventional methods and an experimental study.
AtıfScopus16WoS11OpenAlex18İncele - MakaleAçık Erişim2019Scopus SJRQ1Non-linear rheological (LAOS) behavior of sourdough-based dough
Yildirim-Mavis, Cigdem; Yilmaz, Mustafa Tahsin; Dertli, Enes; Arici, Muhammet; Ozmen, Duygu
During processing, wheat dough is known to undergo large deformation led by mixing and fermentation processes. This deformation is much more pronounced when sourdough is used in the recipe of wheat dough whose gluten is considerably hydrolyzed during sourdough fermentation. This causes deeper effects on rheological properties and shelf life of bakery products. Traditional small amplitude oscillatory tests do not enable us to comprehend the viscoelasticity under large deformations. In this respect, large amplitude oscillatory shear (LAOS) tests are useful for accurate characterization of the non-linear mechanical response. This study, therefore, is undertaken to investigate the non-linear mechanical response of dough prepared with different amounts of sourdough (0, 10, 20 30 and 40%) in a strain values ranging from 0.005 to 200% (frequency at 10 rad/s). As a result, sourdough was determined to have considerable effects on the non-linear viscoelastic response of dough. Strain-stiffening and shear-thinning behaviors were considerably influenced by sourdough incorporation and the dough started to show strain-softening and lowered shear-thinning behavior after giving a peak around at 100% strain due to the onset of the breakdown of the gluten network and suspension of starch matrix as consequence of the metabolic activity of the starter culture (Lactobacillus brevis E25) used in the preparation of sourdough. The physicochemical (pH and TTA), microbiological properties (LAB count) and extensographic properties were also shown to support the LAOS results. LAOS tests could be effectively and clearly used to reveal the effect of processing conditions (sourdough content and deformation by large strain amplitude) on the non-linear mechanical response of wheat dough.
AtıfScopus49WoS46OpenAlex46İncele - MakaleAçık Erişim2019Scopus SJRQ2Investigation of magnetic force properties between different PMGs and multi-seeded YBCO superconductors with different seed distances
Abdioglu, M.; Ozturk, K.; Guner, S.B.; Celik, S.; Kucukomeroglu, T.
The magnetic levitation force in vertical direction and guidance force in lateral direction should be increased for enhancing the loading capacity and stability of Maglev systems, respectively. In this study, we have produced multi‒seeded YBCO (YBa2Cu3O7) superconductors with two seeds and investigated the effect of seed distance on the vertical levitation force and lateral guidance force properties by using different permanent magnetic guideway (PMG) arrangements. Although there are studies in literature related to different distance, orientation and angle of seeds; there is no detailed study investigating the effect of seed distance on the vertical and lateral magnetic force properties of Maglev systems depending on different types of PMGs. In this study, after the sample fabrication, the optimum PMG arrangement were determined by using numerical simulation to obtain magnetic flux density distribution. It is determined that both maximum levitation and guidance force values firstly increased with increasing the seed distance from 0 to 4 mm and then related forces decreased with increasing the seed distance from 4 to 16 mm but still keep the higher force values than the sample with the seed distances of 0 mm. This situation is clarified as the increasing of the seed distance to an optimum value enhances both the levitation and guidance forces simultaneously and this is very important for levitation force applications because it causes to easy control of the Maglev system in vertical and lateral directions.
AtıfScopus4WoS4OpenAlex5İncele - MakaleYalnız künye2018Scopus SJRQ1Effect of ultrasound treatment on the properties of nano-emulsion films obtained from hazelnut meal protein and clove essential oil
Gul, Osman; Saricaoglu, Furkan Turker; Besir, Aysegul; Atalar, Ilyas; Yazici, Fehmi
Hazelnut meal protein (4% (w/v)) and clove essential oil (CEO) (3% (v/v)) were homogenized with ultrasound (US) at different times (2, 4 and 6 min) and amplitudes (50, 75 and 100%) to obtain nano-emulsion films. Film forming nano-emulsions (FFNs) were analyzed for average particle size (Dz) and zeta potential, and edible film characterization were evaluated depending on US treatment, as well as antibacterial and antioxidant activities. Dz values and zeta potential of FFNs decreased with increasing acoustic energy delivered to nano-emulsion system. Thickness and water solubility of films significantly decreased with increasing US treatment. Films became more transparent depending on US treatment probably due to particle size reduction. Tensile strength (TS) of films significantly increased with US treatment, while elongation at break (EAB) slightly increased. Microstructure of films became more homogeneous after US treatment and caused to lower water vapor permeability. Enrichment with CEO has given the films antibacterial activity against L. monocytogenes, B. subtilis, S. aureus, P. aeruginosa and E. coli, and antioxidant activity, and US application has improved these activities. US technology can be used to improve mechanical, barrier and antimicrobial properties of hazelnut meal protein based edible films enriched with CEO.
AtıfScopus158WoS141OpenAlex160İncele - MakaleAçık Erişim2018Scopus SJRQ1A novel method based on thermal conductivity for material identification in scrap industry: An experimental validation
Cuce, Erdem; Cuce, Pinar Mert; Guclu, Tamer; Besir, Ahmet; Gokce, Erkan; Serencam, Ugur; Serencam, Huseyin
Fast, accurate and reliable identification and sorting of materials is still a challenge in recycling sector. Scrap metals are often classified through density and colour, which cause notable financial burdens to the companies in most cases. Within the scope of this research, a novel method based on thermal conductivity is presented for material identification in scrap industry. The unit consists of a constant heat flux source and a cooling system, in which axial heat conduction is enabled and radial heat transfer is eliminated. For the steady-state conditions, temperature gradient across the sample metals is measured along with the constant heat flux value, and the thermal conductivity of the samples is determined via the Fourier's heat conduction law. Copper, brass and stainless steel samples are considered in this research to verify the accuracy of the results. For a reliable and scientific approach, three independent sets of experiments are conducted, and the results are evaluated in terms of accuracy and consistency. Experimental thermal conductivity values of the said samples are compared with the reported data in literature and a good accordance is achieved. Error in measurements is calculated to be 1.37, 3.31 and 4.46% for copper, brass and stainless steel sample, respectively which is acceptable. The tests are repeated with highly sensitive probes for aluminium sample, and the measurement error is calculated to be 0.56%.
AtıfScopus21WoS19OpenAlex19İncele - MakaleYalnız künye2018Scopus SJRQ2Levitation and guidance force relaxations of the single−seeded and multi−seeded YBCO superconductors
Abdioglu, M.; Ozturk, K.; Kabaer, M.; Ekici, M.
The stable levitation and guidance forces at higher force levels are important parameters for technological applicability of high temperature superconductors (HTSs) in Maglev and Flywheel energy storage systems. In this study, we have investigated the levitation and guidance force relaxation of both the single-seeded and multi-seeded YBCOs for different (HTS)−permanent magnetic guideway (PMG) arrangements in different cooling heights (CH). The measured saturated force values of Halbach PMG arrangements are bigger than the maximum force values of other PMGs. It is determined that the normalized magnetic levitation force (MLF) and normalized guidance force (GF) relaxation rate values decrease while the relaxation rates increase with increasing magnetic pole number and the effective external magnetic field area for both the single−seeded and multi−seeded YBCO. Also it can be said that the force stability at the higher force value of Halbach PMG arrangement indicates that the relaxation quality of Halbach PMG is better than that of the others. Additionally, it can be said that both the MLF and GF relaxation qualities of the multi−seeded YBCOs are better than that of the single−seeded ones. This magnetic force and relaxation results of the single−seeded and multi−seeded YBCOs are useful to optimize the loading capacity and lateral reliability of HTS Maglev and similar magnetic bearing systems.
AtıfScopus5WoS5OpenAlex6İncele - MakaleYalnız künye2017Scopus SJRQ1Noniterative complex permittivity retrieval using calibration-independent waveguide measurements
Hasar, Ugur Cem; Kaya, Yunus
Calibration-independent nonresonant measurements can be employed to eliminate the need for calibration before microwave measurements. These methods generally assume that the location of the sample in its measurement cell is known after the sample is positioned or shifted within the cell and that the length of the measurement cell is known. In addition, in general these methods necessitate some sort of numerical analysis to retrieve the complex permittivity of the sample. In this research paper, we propose a calibration-independent nonresonant waveguide method to first eliminate measurement errors arising from inaccurate knowledge of the location of the sample within its cell (after shifting) and arising from improper knowledge of the length of the measurement cell and second to determine the complex permittivity explicitly. In addition, our proposed method needs scattering parameter measurements from three different measurement configurations – another improvement with respect to a similar calibration-independent method requiring measurements from four different configurations. Furthermore, it does not necessitate that the sample be flushed to the measurement cell. We analyzed repeatability of cell connection and investigated uncertainty in the measurement of complex permittivity for a change in length of the sample and the cell and when air gap present between sample surfaces and guide walls. We validated the proposed method by measuring the complex permittivity of polyethylene sample and distilled water at X-band (8.2–12.4 GHz).
AtıfScopus8WoS8OpenAlex8İncele - MakaleYalnız künye2017Scopus SJRQ1Purification of camel liver catalase by zinc chelate affinity chromatography and pH gradient elution: An enzyme with interesting properties
Chafik, Abdelbasset; Essamadi, Abdelkhalid; Çelik, Safinur Yildirim; Mavi, Ahmet
Climate change and increasing temperatures are global concerns. Camel (Camelus dromedarius) lives most of its life under high environmental stress in the desert and represent ideal model for studying desert adaptation among mammals. Catalase plays a key role in protecting cells against oxidative stress. For the first time, catalase from camel liver was purified to homogeneity by zinc chelate affinity chromatography using pH gradient elution, a better separation was obtained. A purification fold of 201.81 with 1.17% yield and a high specific activity of 1132539.37 U/mg were obtained. The native enzyme had a molecular weight of 268 kDa and was composed of four subunits of equal size (65 kDa). The enzyme showed optimal activity at a temperature of 45 °C and pH 7.2. Thiol reagents, β-Mercaptoethanol and D,L-Dithiothreitol, inhibited the enzyme activity. The enzyme was inhibited by Al3+, Cd2+ and Mg2+, whereas Ca2+, Co2+ and Ni2+ stimulated the catalase activity. Reduced glutathione has no effect on catalase activity. The Km and Vmax of the enzyme for hydrogen peroxide were 37.31 mM and 6185157 U/mg, respectively. Sodium azide inhibited the enzyme noncompetitively with Ki value of 14.43 μM, the IC50 was found to be 16.71 μM. The properties of camel catalase were different comparing to those of mammalian species. Relatively higher molecular weight, higher optimum temperature, protection of reduced glutathione from hydrogen peroxide oxidation and higher affinity for hydrogen peroxide and sodium azide, these could be explained by the fact that camel is able to live in the intense environmental stress in the desert.
AtıfScopus9WoS9OpenAlex10İncele - MakaleAçık Erişim2016Scopus SJRQ1An experimental study on the ultra-fine grinding of gypsum ore in a dry ball mill
Öksüzoğlu, Bilge; Uçurum, Metin
Gypsum is a crystalline form of hydrated calcium sulfate (CaSO4·2H20) generally used in cements and plasters in the construction industry, though also in paints, fertilizers, medicines, papers, and textiles. For use in these materials, gypsum must be ground finely (<100 μm), if not ultra-finely (<10 μm), for which ball mills are most effective. Despite gypsum's widespread use and the regular need to grind it, studies concerning the grinding of gypsum ore remain scarce. In response, in this study, we have systematically investigated how certain grinding parameters (i.e., mill speed, ball filling ratio, ball size distribution, powder filling ratio, grinding aid ratio, and grinding time) of conventional dry ball mills affect the grindability of gypsum ore. We determined the properties of the micronized gypsum products obtained in optimal grinding conditions, and the results showed that the dry ball mill grinding process can effectively produce ultra-fine gypsum products.
AtıfScopus38WoS32OpenAlex42İncele