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Publisher: Süleyman Demirel Üniversitesi   (Total: 1 journals)   [Sort by number of followers]

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Süleyman Demirel Üniversitesi Fen Bilimleri Enstitüsü Dergisi     Open Access  
Süleyman Demirel Üniversitesi Fen Bilimleri Enstitüsü Dergisi
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  This is an Open Access Journal Open Access journal
   ISSN (Print) 1300-7688 - ISSN (Online) 1308-6529
   Published by Süleyman Demirel Üniversitesi Homepage  [1 journal]
  • Kapak ve İçindekiler

    • Authors: Kapak ve İçindekiler
      Abstract: -
      PubDate: 2017-04-15
      Issue No: Vol. 21, No. 1 (2017)
       
  • The Physical Meaning of the Rényi Relative Entropy

    • Authors: Gökhan Barış BAĞCI
      Abstract: The Boltzmann-Gibbs relative entropy provides the difference between the off-equilibrium and equilibrium free energy terms associated with Boltzmann-Gibbs entropy. In this work, we studied whether this physical meaning can be given to R\'{e}nyi relative entropy definition. We find that this is possible only in the limit as $q$ approaches to 1. This shows that R\'{e}nyi relative entropy has a physical meaning only when the system can already be explained by ordinary Boltzmann-Gibbs entropy. We also note that this result is independent of the internal energy constraint employed.
      PubDate: 2017-03-31
      Issue No: Vol. 21, No. 1 (2017)
       
  • Green's Function and Periodic Solutions of a Spring-Mass System in
           which the Forces are Functionally Dependent on Piecewise Constant Argument
           

    • Authors: Duygu ARUĞASLAN, Nur CENGİZ
      Abstract: In this paper, damped spring-mass systems with generalized piecewise constant argument and with functional dependence on generalized piecewise constant argument are considered. These spring-mass systems have piecewise constant forces of the forms $Ax(\gamma(t))$ and $Ax(\gamma(t))+h(t,x_{t},x_{\gamma(t)})$, respectively. These spring-mass systems are examined without reducing them into discrete equations. While doing this examination, we make use of the results which have been obtained for differential equations with functional dependence on generalized piecewise constant argument in \cite{2}. Sufficient conditions for the existence and uniqueness of solutions of the spring-mass system with functional dependence on generalized piecewise constant argument are given. The periodic solution of the spring-mass system which has functional force is created with the help of the Green's function, and its uniqueness is proved. The obtained theoretical results are illustrated by an example. This illustration shows that the damped spring-mass systems with functional dependence on generalized piecewise constant argument with proper parameters has a unique periodic solution which can be expressed by Green's function.
      PubDate: 2017-03-29
      Issue No: Vol. 21, No. 1 (2017)
       
  • Distribution Dynamics of Vegetative Cells and Cyst of Ceratium
           hirundinella in Two Reservoirs, Turkey

    • Authors: Elif TEZEL ERSANLI, Seda HASIRCI MUSTAK
      Abstract: The seasonal variation and vertical and horizontal distributions of Ceratium hirundinella (O.F.Müller) Dujardin and occurrence of its cyst form in Erfelek and Dodurga Reservoirs (Sinop, Turkey) were studied between August 2010 and July 2011. Our results showed that cyst form was observed with vegetative cells in phytoplankton. Ceratium hirundinella was recorded in high numbers in autumn/winter periods in these reservoirs. Winter conditions did not affect presence/absence of the species, but influenced the cell densities. Vegetative cells were observed mostly in lacustrine and transition zones, horizontally in two reservoirs and also cyst form was recorded in Erfelek Reservoir but not found in Dodurga Reservoir vertically. Dissolved oxygen had positive correlation with vegetative cells and also pH, conductivity and redox potential were important factors for vegetative cells and cyst occurrence.
      PubDate: 2017-03-27
      Issue No: Vol. 21, No. 1 (2017)
       
  • Carbon Nanotube Modified Screen Printed Electrodes: Pyranose Oxidase
           Immobilization Platform for Amperometric Enzyme Sensors

    • Authors: Dilek ODACI DEMIRKOL, Caglar OZDEMIR, Roberto PILLOTON, Suna TIMUR
      Abstract: Here, a novel enzymatic biosensor was developed using multiwalled carbon nanotube including screen printed electrodes (MWCNT-SPE). Pyranose oxidase (PyOx) was immobilized on the electrode surface by way of gelatin membrane and then cross-linked using glutaraldehyde. Glucose was detected at -0.7 V (vs. Ag/AgCl) by watching consumed oxygen in enzymatic reaction after addition substrate. After optimization of pH and enzyme loading, the linearity was found in the range of 0.1–1.0 mM of glucose. After that, the effect of MCNT on the current was tested. Also the enzymatic biosensor including glucose oxidase instead of pyranose oxidase was prepared and the biosensor response followed for glucose. Furthermore, this system was tested for glucose analysis in soft drinks.
      PubDate: 2017-03-27
      Issue No: Vol. 21, No. 1 (2017)
       
  • Structural Modelling and Structure-Function Analysis of Zymomonas mobilis
           Levansucrase

    • Authors: Bahar BAKAR, Burcu KAPLAN-TÜRKÖZ
      Abstract: Levansucrases are bacterial enzymes which produce fructan polymers from sucrose via hydrolysis and transfructosylation activities. These polymers; levan and fructooligosaccharides are valuable for food and pharmaceutical industries. Levansucrases from Gram-positive bacteria such as Bacillus subtilis tend to produce levan, while those from Gram-negative bacteria preferentially produce fructooligosaccharides. Zymomonas mobilis is an efficient levansucrase producer and its extracellular levansucrase can produce both fructooligosaccharides and levan depending on the reaction parameters. In this study, the structure of Z. mobilis levansucrase was modeled in order to help to understand the structure-function relationship of the enzyme. Furthermore, amino acids previously reported to be important for levansucrase activity were mapped on the model. The structural model presents a five-bladed propeller with a deep, negatively charged central pocket, similar to other bacterial levansucrases. Mapping showed that amino acids which previously reported to affect fructan length are located on the periphery of the structure covering the active site central pocket. Thus it is showed that, for the first time, that hydrolysis and transfructosylation reactions are catalyzed on different parts of Z. mobilis levansucrase structure. The structural location of the critical amino acids will pave the way to identify other residues which control fructan length by site directed mutagenesis without altering the overall fold of the enzyme.
      PubDate: 2017-03-23
      Issue No: Vol. 21, No. 1 (2017)
       
  • Performances of Hybrid Dent Maize Cultivars in Bingöl Conditions

    • Authors: Kağan KÖKTEN, Mevlüt AKÇURA
      Abstract: The research was conducted with aim to investigate adaptation capability of twenty five hybrid dent corn cultivars, and to determine relationships among traits in maize at Bingol, East Anatolia Region, conditions of Turkey during 2014 and 2015 growing seasons. The experiment was set up according to the Randomized Complete-Block Design with three replicates. Results of the research showed that differences among the grain yields and yield components of cultivars were statistically significant in both years. The highest and the lowest value of yield components varied according to cultivars and years. The grain yield of maize cultivars varied in between 5521.3-10442.0 kg ha-1 in the first year and in between 6362.0-14296.7 kg ha-1 in the second year. The highest grain yields were determined in ADV-2898 cultivar (10442.0 kg ha-1) in the first year and Tuano cultivar (14296.7 kg ha-1) in the second year. The lowest grain yield was identified in Şafak cultivar (5521.3 kg ha-1) in the first year and Dian cultivar (6362.0 kg ha-1) in the second year. According to correlation analysis, grain yield was positively and significantly correlated with ear length, ear diameter number of kernel per ear, ear weight and 1000 grain weight of maize. The non-significant correlations were determined in between grain yield with plant height and stem diameter.
      PubDate: 2017-03-08
      Issue No: Vol. 21, No. 1 (2017)
       
  • The Effect of Heat Treatment on Physical, Chemical and Structural
           Properties of Calcium Sulfate Based Scaffolds

    • Authors: Hakan OFLAZ, Betül ALDEMİR DİKİCİ, Serkan DİKİCİ
      Abstract: 3D printed calcium sulfate (CS) is a promising material for on custom bone substitutes. Since it dissolves easily in body fluids, manufactured samples require to being improved to reduce solubility.  The main aim of this study was reducing the dissolubility of CS based samples by using sintering and investigating the effect of heat treatment on their physical, chemical and structural properties. To observe the effect of heat treatment on samples, contact angles were measured, X-Ray diffraction analysis (XRD) was performed, and scanning electron microscope (SEM) micrographs were captured before and after the sintering process, and the results were compared. Furthermore, sintered and non-sintered samples were soaked in phosphate buffered saline (PBS) to observe the impact of sintering on the solubility of the material. Also, three different pore sized scaffolds were manufactured to test the limits of the 3D printer for manufacturing of scaffolds with open pores. Sintering process results in a volume reduction and according to SEM results, CS grains were fused together after heat treatment. Although non-sintered CS sample starts to dissolve in high rate and nearly 1/3 of the sample was at the bottom of the glass in a matter of minutes, sintering creates more rigid structure and there were not visible dissolution in PBS at the end of a week. The contact angle of samples cannot be measured, so it can be concluded that 3D printed material showed a super-hydrophilic property. XRD diagram suggested that there is not any new phase created in the printing and sintering processes except related hydrates of CS. As a result of the 3D printing, 500 µm, 750 µm and 1000 µm pore sized scaffolds were manufactured, successfully. However, it was seen that 500 µm pores could not be open by using depowdering after the printing process.
      PubDate: 2017-03-01
      Issue No: Vol. 21, No. 1 (2017)
       
  • Integrable G2 Structures on 7-dimensional
           3-Sasakian Manifolds

    • Authors: Nülifer ÖZDEMİR, Şirin AKAY
      Abstract: It is known that there exist canonical and nearly parallel $G_2$ structures on 7-dimensional 3-Sasakian manifolds. In this paper, we investigate the existence of $G_2$ structures which are neither canonical nor nearly parallel. We obtain eight new $G_2$ structures on 7-dimensional 3-Sasakian manifolds which are of general type according to the classification of $G_2$ structures by Fernandez and Gray. Then by deforming the metric determined by the $G_2$ structure, we give integrable $G_2$ structures. On a manifold with integrable $G_2$ structure, there exists a uniquely determined metric covariant derivative with anti-symetric torsion. We write torsion tensors corresponding to metric covariant derivatives with skew-symmetric torsion. In addition, we investigate some properties of torsion tensors.
      PubDate: 2017-02-18
      Issue No: Vol. 21, No. 1 (2017)
       
  • Analysis of the Mosaic Defects in Graded and Non Graded InxGa1-xN Solar
           Cell Structures

    • Authors: İlknur KARS DURUKAN, Mustafa Kemal ÖZTÜRK, Süleyman ÖZÇELİK, Ekmel ÖZBAY
      Abstract: In this study, graded (A) InxGa1-xN (10.5 ≤ x ≤ 18.4) and non graded (B) InxGa1-xN (13.6 ≤ x ≤ 24.9) samples are grown on c-oriented sapphire substrate using the Metal Organic Chemical Vapour Deposition (MOCVD) technique. The structural, optical and electrical features of the grown InGaN/GaN solar cell structures are analyzed using High Resolution X-Ray Diffraction (HRXRD), Photoluminescense (PL), Ultraviolet (UV), current density and potential (JV) measurements. According to the HRXRD results; it is determined that the InGaN layer of the graded structure has a lower FWHM (Full width at half maximum) value. From the PL measurements, it is observed that the GaN half-width peak value of the graded sample is narrower and the InGaN peak width value of the graded sample is larger. From UV measurements, that the graded sample has a greater band range. JV measurements determine that the performance of the graded structure is higher.
      PubDate: 2017-02-03
      Issue No: Vol. 21, No. 1 (2017)
       
  • Manufacturing and Characterization of Roof Tiles a Mixture of Tile Waste
           and Coal Fly Ash

    • Authors: Aysel KANTÜRK FİGEN, Ünal ÖZÇAY, Sabriye PİŞKİN
      Abstract: The study presented in this manuscript focuses on the manufacturing of roof tiles bearing a mixture of tile waste and coal fly ash. A roof tile sample at a different composition was prepared to attain consistence in quality. The conversion factors were described to be able to convert the laboratory results for firing strength and water absorption into the industrial operating conditions. It was determined that the replacement mixture of the tile waste as well as the Tunçbilek fly ash together with the Muttalip clay as the raw material allowed the manufacturing of good quality roof tiles. Seyitömer fly ash was not suitable for use as secondary raw material due to the presence of tile waste with higher SO3 and CaO contents and lower MgO content. In addition to this, maximum 5 % Tunçbilek fly ash samples in the composition of roof tiles provided favorable physical and mechanical characteristics of the commercial product.
      PubDate: 2017-01-14
      Issue No: Vol. 21, No. 1 (2017)
       
  • Side Effects of Four Acaricides on the Predatory Mites of Neoseiulus
           californicus McGregor and Phytoseiulus persimilis Athias-Henriot (Acari:
           Phytoseiidae)

    • Authors: Sibel YORULMAZ SALMAN, İrfan TURAN
      Abstract: In the present study determined the side effects of four acaricides of acequinocyl, etoxazole, bifenazate and milbemectin on the predator mites Phytoseiulus persimilis Athias-Henriot and Neoseiulus californicus McGregor. Acaricide concentrations were prepared as a two times the field application dose (2T), field application dose (T), and half of the field application dose (T/2) and were then applied on eggs, nymphs and adults of the P. persimilis and N. californicus. The side effects of the acaricidesapplied to the predator mites were determined three, five and seven days afterthe application. While all doses of acequinocyl and etoxazole showed a higher toxic effect on N.californicus eggs, it was found that bifenazate and milbemectin caused similar effects on both predator mite eggs. Furthermore, it was found that the toxic effects of acequinocyl, etoxazole, bifenazate and milbemectin on nymphs and adults of the predator miteswere high seventh day after the application. The results of the study showed that four acaracides frequently used against to pest mites, should be used more carefully in the agricultural areas.
      PubDate: 2017-01-05
      Issue No: Vol. 21, No. 1 (2017)
       
 
 
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