Sürdürülebilir Kalkınma Amaçları
Yazarlar
- Ashyralyev, A(8)
- Malkowsky, E(8)
- Ashyralyyev, Charyyar(7)
- Yilmaz, Ozgur(7)
- Ozdes, Duygu(6)
- Cakir, Zafer(5)
- Doğru, Bülent(5)
- Duran, Celal(5)
- Kahraman, Yakup(5)
- Arslan, Mehmet(4)
- Ashyralyev, Allaberen(4)
- Ayaydin, Hasan(4)
- Karaman, Safa(4)
- Kayacier, Ahmed(4)
- Yildirim, Mustafa(4)
- Yildiz, Salih(4)
- Yüksel, Ferhat(4)
- Aksoy, Metin(3)
- Bertan, Münevver(3)
- Cengiz, Ekrem(3)
- Doğan, Kadir Caner(3)
- Kartopu, Saffet(3)
- Kurt, Kemal(3)
- Recepoğlu, Mürşit(3)
- Sipahi, Ferkan(3)
- Temizel, Irfan(3)
- Yildiz, Emel(3)
- Yildiz, Hilal(3)
- Adanur, Hakan(2)
- Akar, Bülent(2)
- Akaryali, Enver(2)
- Akpinar, A. Sefa(2)
- Akpinar, Adem(2)
- Akyüz, Ahmet Mutlu(2)
- Ar, Ilker Murat(2)
- Arslantunali, D.(2)
- Artan, Seyfettin(2)
- Aslan, Zafer(2)
- Aydin, Faruk(2)
- Baki, Birdoğan(2)
Yayınlar
- BildiriYalnız künye2014Approximate solution of the two-dimensional singular integral equation
Ashyralyyev, Charyyar; Cakir, Zafer; Ashyralyev, A; Malkowsky, E
Approximate quadrature formulas for the numerical calculation of the two-dimensional Vekua potential and singular integrals are obtained. The mechanical quadrature method for the two-dimensional quasilinear singular integral equation with Vekua operators is described. The numerical results are compared with the exact solution of the integral equation.
- MakaleYalnız künye2014Geochemical and Sr-Nd isotopic characteristics of Murgul (Artvin) volcanic rocks in the Eastern Black Sea Region (Northeast Turkey)
Sipahi, Ferkan; Sadiklar, M. Burhan; Şen, Cüneyt
The studied volcanic rocks are footwall and hanging wall dacites from the Murgul mine and the surrounding area. Moreover, the hanging wall dacites contain enclaves. Footwall dacite contains biotite, whereas hanging wall dacitic rocks contain hornblende as a ferromagnesian mineral. The enclaves in the hanging wall dacite have sizes that range from 1cm to 20cm and contain hornblende as a ferromagnesian mineral. The volcanic rocks show tholeiitic and transitional affinities. They are rich in large ion lithophile element and light rare earth element with pronounced depletion of high field strength elements. The chondrite-normalized rare earth element patterns (LaN/LuN=1.47-5.12) show low to medium enrichment, which reveal that the rocks were obtained from similar sources in Murgul volcanic rocks. The initial 87Sr/86Sr values range from 0.70442 to 0.70525, and the initial 143Nd/144Nd values range from 0.512741 to 0.512770. The main solidification processes involved in the evolution of the volcanic rocks consist of fractional crystallization with minor amounts of crustal contamination and magma mixing. All geochemical data support that these rocks originated from andesitic magma, and that the parental magma of the rocks were probably derived from an enriched upper mantle, previously modified by subduction-induced metasomatism in a geodynamic setting.
- MakaleYalnız künye2014A new 5,6-dihydro-2-pyrone derivative from Phomopsis amygdali, an endophytic fungus isolated from hazelnut (Corylus avellana)
Akay, Şeref; Ekiz, Güner; Kocabaş, Fatma; Hameş-Kocabaş, E. Esin; Korkmaz, Kemal S.; Bedir, Erdal
Aims of this study were to isolate endophytes from different parts of hazelnut - Corylus avellana L. to obtain bioactive secondary metabolites and search for the presence of gene region of taxadiene synthase (Ts), a key enzyme in taxol biosynthesis, on selected fungi. Fourteen fungal species were isolated and cultured for the screening studies. The cell-free fermentation broths were extracted with chloroform. The chloroform extracts were tested for cytotoxic activity by MTT method. Based on the activity results and chemical profiles, the isolate identified as Phomopsis amygdali by internal transcribed spaces (ITS) sequence analysis using ITS1 primer was selected for further studies. After large-scale fermentation and purification studies, two major compounds, one of which turned out to be a new secondary metabolite, were isolated and characterized. Structure of the new metabolite was elucidated as (S)-4-butoxy-6-((S)-1-hydroxypentyl)-5,6-dihydro-2H-pyran-2-one by the extensive use of 1D and 2D NMR, and HR-MS, whereas the known compound was identified as (-)pestalotin. Additionally, to evaluate taxol-producing potential of the selected isolate, a PCR amplification study followed by gel electrophoresis analysis was carried out revealing no Ts gene region.
- MakaleYalnız künye2014New thiophene-1,2,4-triazole-5(3)-ones: Highly bioactive thiosemicarbazides, structures of Schiff bases and triazole-thiols
Ünver, Yasemin; Sancak, Kemal; Çelik, Fatih; Birinci, Emrah; Küçük, Murat; Soylu, Serkan; Burnaz, Nesibe Arslan
Key compound 2-(4-amino-5-oxo-3-(thiophene-2-ylmethyl)-4,5-dihydro-1,2,4- tiazole-1-yl) acetohydrazide (3) was synthesized by reacting hydrazine hydrate with ethyl-2-(4-amino-5-oxo-3-(thiophene-2-ylmethyl)-4,5-dihydro-1,2,4-tiazole- 1yl)acetate (2), obtained in basic media from 4-amino-5-(thiophene-2-ylmethyl)- 2H-1,2,4-triazole-3(4H)-one (1). Compound 3 was converted to thiosemicarbazide derivatives (4a-d) and Schiff base derivatives 6a-e and 7a-e. The treatment of compound 4 with NaOH gave 4-amino-2-((4-(4-aryl)-5-mercapto-4H-1,2,4-triazole-3- yl)methyl)-5-(thiophene-2-ylmethyl)-2H-1,2,4-triazole-3(4H)-ones (5a-d). All newly compounds, well characterized by elemental analyses, IR, 1H NMR, 13C NMR and mass spectral studies were tested for their antioxidant and antimicrobial activities. Thiosemicarbazide derivatives (4a-d) were highly active in two antioxidant tests with 69.0-88.2% DPPH scavenging and 503-1257 μM TEAC values, while the others showed lower or no activity. The results of the two antioxidant tests correlated well. Moreover, Thiosemicarbazide derivatives (4a-d) also showed antibacterial activity against Staphylococcus aureus, Bacillus cereus, and Mycobacterium smegmatis. Thiosemicarbazide group deserves attention in the synthesis of bioactive compounds.
- Derleme MakaleAçık Erişim2014Peripheral nerve conduits: Technology update
Arslantunali, D.; Dursun, T.; Yucel, D.; Hasirci, N.; Hasirci, V.
Peripheral nerve injury is a worldwide clinical problem which could lead to loss of neuronal communication along sensory and motor nerves between the central nervous system (CNS) and the peripheral organs and impairs the quality of life of a patient. The primary requirement for the treatment of complete lesions is a tension-free, end-to-end repair. When end-to-end repair is not possible, peripheral nerve grafts or nerve conduits are used. The limited availability of autografts, and drawbacks of the allografts and xenografts like immunological reactions, forced the researchers to investigate and develop alternative approaches, mainly nerve conduits. In this review, recent information on the various types of conduit materials (made of biological and synthetic polymers) and designs (tubular, fibrous, and matrix type) are being presented.
- BildiriYalnız künye2014A note on fractional parabolic differential and difference equations
Ashyralyev, Allaberen; Artykov, Merdan; Cakir, Zafer; Ashyralyev, A; Malkowsky, E
In this work, the first and second order of difference schemes that approximately solve the initial-boundary value problem for multidimensional fractional parabolic equation with Dirichlet boundary condition are presented. The stability estimates for the solution of these difference schemes are established.
- MakaleAçık Erişim2014Preparation of a new sorbent, cetyltrimethylammonium bromide (CTAB)-modified obsidian, for the separation, preconcentration of Pb(II), Cd(II) ions in food and water samples
Ozdes, Duygu; Duran, Celai
Cetyltrimethylammonium bromide (CTAB)-modified obsidian (CTAB-OB) was utilized as a new sorbent for the separation and preconcentration of Pb(II) and Cd(II) ions by solid phase extraction in some environmental samples prior to their flame atomic absorption spectrophotometric determination. The characterization of CTAB-OB was performed by BET surface area,FTIR and SEM techniques. The effects of significant analytical parameters,including pH of the aqueous solution,eluent type,concentration and volume,CTAB-OB amount,sample volume,adsorption and desorption contact time,were evaluated in detail on the recovery of the analyte ions. The adsorption capacity of CTAB-OB was found to be 48.8 and 43.4 mg g-1 for the Pb(II) and Cd(II) ions,respectively. The detection limits for the analyte ions were 0.89 μg L-1 for Pb(II) and 0.37 μg L-1 for Cd(II),while the relative standard deviations were lower than 3.5% for both of them. In order to ensure the accuracy of the method,certified reference material (CRM-SA-C Sandy Soil C) analyses and spike tests were performed. Then the proposed method was applied to sea and stream water,black tea,and Turkish and import coffee samples to determine their Pb(II) and Cd(II) contents.
- MakaleAçık Erişim2014Dynamic mechanical spectra of selected turkish honeys: Construction of predictive models for complex viscosity using two different nonlinear modeling techniques
Kayacier, Ahmed; Yüksel, Ferhat; Karaman, Safa
Dynamic oscillatory shear rheological characteristics of honey samples from different floral sources were evaluated using frequency sweep test and stress sweep test at three different temperatures (10, 15, and 20°C). All honey samples showed liquid-like behavior because the loss modulus was significantly greater than the elastic modulus. Pine honey showed the highest complex viscosity (86.33 Pa s at 10°C), while the lowest complex viscosity was observed in citrus honey (22.15 Pa s) at the same temperature. Temperature dependency of complex viscosity of honey samples was modeled by Arrhenius model and activation energy values of honeys ranged from 83.13 to 97.46 kJ/mol. An efficient predictive model for complex viscosity values of honeys was constructed using adaptive neuro fuzzy inference system that showed satisfactory prediction performance with high coefficient of determination (0.995) and low root mean square error (0.04) in the validation period compared to artificial neural networks.
- MakaleYalnız künye2014Synthesis and carbonic anhydrase inhibitory effects of novel sulfamides derived from 1-aminoindanes and anilines
Akbaba, Yusuf; Bastem, Enes; Topal, Fevzi; Gülçin, Ilhami; Marasç, Ahmet; Göksu, Süleyman
Three 1-aminoindanes, four anilines and BnOH or t-BuOH were reacted with chlorosulfonyl isocyanate to give sulfamoyl carbamates. Pd-C catalysed hydrogenolysis reactions of carbamates or deprotection of the Boc group of the carbamates with CF3CO2H afforded seven novel sulfamides. Human carbonic anhydrase (hCA) isoenzymes I and II (hCA I and hCA II) were purified from fresh human blood erythrocytes with onestep affinity chromatography on Sepharose 4B-tyrosine-sulfanilamide. The inhibitory properties of the novel sulfamides on both isoenzymes were determined using the esterase activity with 4-nitrophenyl acetate (NPA) as substrate. The tested novel sulfamides derived from 1-aminoindanes and anilines effectively inhibited hCA I and II competitively in the nanomolar range. Among these compounds, the novel sulfamide derivative 17 showed themost potent inhibitory effect against hCA I (Ki: 153.88 nM), while sulfamide derivative 26 showed the highest inhibitory potential against hCA II (Ki: 117.80nM).
- MakaleYalnız künye2014Empirical findings on triplet deficits hypothesis: The case of Turkey
Şen, Ali; Şentürk, Mehmet; Sancar, Canan; Akbaş, Yusuf Ekrem
The aim of this study is to investigate the concept of triplet deficits in Turkey between 1980 and 2010. "Dolado-Lütkepohl Granger Causality Analysis" was performed in order to determine the direction of the relationship among the variables. In addition, the Vector Autoregressive (VAR), Variance Decomposition and Impulse-Response analysis were performed to determine the degree to which variables affected each other. The study finds that triplet deficit hypothesis was valid in Turkey between 1980 and 2010.
- MakaleYalnız künye2014Determination of structural behavior of Bosporus suspension bridge considering construction stages and different soil conditions
Günaydin, Murat; Adanur, Süleyman; Altunişik, Ahmet Can; Sevim, Bariş; Türker, Emel
In this paper, it is aimed to determine the structural behavior of suspension bridges considering construction stages and different soil conditions. Bosporus Suspension Bridge connecting the Europe and Asia in Istanbul is selected as an example. Finite element model of the bridge is constituted using SAP2000 program considering existing drawings. Geometric nonlinearities are taken into consideration in the analysis using P-Delta large displacement criterion. The time dependent material strength of steel and concrete and geometric variations is included in the analysis. Time dependent material properties are considered as compressive strength, aging, shrinkage and creep for concrete, and relaxation for steel. To emphases the soil condition effect on the structural behavior of suspension bridges, each of hard, medium and soft soils are considered in the analysis. The structural behavior of the bridge at different construction stages and different soil conditions has been examined. Two different finite element analyses with and without construction stages are carried out and results are compared with each other. At the end of the analyses, variation of the displacement and internal forces such as bending moment, axial forces and shear forces for bridge deck and towers are given in detail. Also, displacement and stresses for bridge foundation are given with detail. It can be seen from the analyses that there are some differences between both analyses (with and without construction stages) and the results obtained from the construction stages are bigger. It can be stated that the analysis without construction stages cannot give the reliable solutions. In addition, soil condition have effect on the structural behavior of the bridge. So, it is thought that construction stage analysis using time dependent material properties, geometric nonlinearity and soil conditions effects should be considered in order to obtain more realistic structural behavior of suspension bridges.
- BildiriYalnız künye2014Approximation of the inverse elliptic problem with mixed boundary value conditions
Ashyralyyev, Charyyar; Dedeturk, Mutlu; Ashyralyev, A; Malkowsky, E
The inverse problem for the multidimensional elliptic equation with Neumann-Dirichlet conditions are presented. For the approximate solution of this inverse problem the first and second order of accuracy in t and in space variables difference schemes are constructed. The stability, almost coercive stability and coercive stability estimates for the solution of these difference schemes are obtained. The algorithm for approximate solution is tested in a two-dimensional inverse problem.
- MakaleYalnız künye2014Assessment of kinetics, thermodynamics and equilibrium parameters of Cr(VI) biosorption onto Pinus brutia Ten
Ozdes, Duygu; Gundogdu, Ali; Kemer, Baris; Duran, Celal; Kucuk, Murat; Soylak, Mustafa
The aim of the present study was to investigate the sorption potential of pine bark (Pinus brutia Ten.) for removal of Cr(VI) ions from aqueous solutions. The biosorption characteristics of Cr(VI) ions onto bark biomass were examined with respect to the changes in initial pH of the solution, contact time, initial Cr(VI) and bark concentration, bark particle size, temperature, etc. The biosorption isotherms were described by means of Langmuir and Freundlich models and the biosorption kinetics were analysed using pseudo-first-order, pseudo-second-order and intraparticle diffusion models. The thermodynamic parameters proved that the process was feasible, spontaneous and endothermic in nature.
- MakaleYalnız künye2014Influence of wall flexibility on dynamic response of cantilever retaining walls
Cakir, Tufan
A seismic evaluation is made of the response to horizontal ground shaking of cantilever retaining walls using the finite element model in three dimensional space whose verification is provided analytically through the modal analysis technique in case of the assumptions of fixed base, complete bonding behavior at the wall-soil interface, and elastic behavior of soil. Thanks to the versatility of the finite element model, the retained medium is then idealized as a uniform, elastoplastic stratum of constant thickness and semi-infinite extent in the horizontal direction considering debonding behavior at the interface in order to perform comprehensive soil-structure interaction (SSI) analyses. The parameters varied include the flexibility of the wall, the properties of the soil medium, and the characteristics of the ground motion. Two different finite element models corresponding with flexible and rigid wall configurations are studied for six different soil types under the effects of two different ground motions. The response quantities examined incorporate the lateral displacements of the wall relative to the moving base and the stresses in the wall in all directions. The results show that the wall flexibility and soil properties have a major effect on seismic behavior of cantilever retaining walls and should be considered in design criteria of cantilever walls. Furthermore, the results of the numerical investigations are expected to be useful for the better understanding and the optimization of seismic design of this particular type of retaining structure.
- MakaleYalnız künye2014Exergetic analysis of using the gaseous fuels in spark ignition engines
Sezer, Ismet; Bilgin, Atilla
This paper aims to investigate the use of alternative gaseous fuels in spark ignition engines via an exergy analysis. A quasi-dimensional two-zone thermodynamic cycle model is used for this purpose. The intake and exhaust processes are computed by a simple approximation method, and the processes (that is, compression, combustion, and expansion) are simulated in detail. The turbulent flame propagation process is used for the combustion simulation. The second law of thermodynamics is applied to the cycle model to perform the exergy analysis. The exergy transfers associated with heat, work, and exhaust; the irreversibilities, thermomechanical exergy, fuel chemical exergy, and total exergy have been computed in the exergy analysis. A distribution of the fuel exergy, the energy-based (the first law) efficiency, and the exergetic (the second law) efficiency were also calculated during the exergy analysis. Thus, the effects of using natural gas and liquefied petroleum gas on the exergetic terms and the efficiencies are investigated. The results of the study show that investigated alternative gaseous fuels have affected the variations in the exergy transfers, irreversibilities, and efficiencies. The gaseous fuels are suitable from the exergy point of view because of the lessened exergy destruction rate, but they suffer from the engine performance reduction.
- MakaleYalnız künye2014Are output fluctuations transitory in the MENA region?; [Jesu li fluktuacije proizvodnje tranzitorne u mena regiji?]
Doǧru, Bülent
This study analyzes the nonstationarity of per capita real GDP for 11 Middle East and North Africa (MENA) Countries over the period 1970 to 2012 using two recently developed methods. SURADF and CADF panel unit root tests allowing for cross sectional dependence are used to determine whether output fluctuations are permanent or transitory. Contrary to the traditional view of business cycle, we Find econometric evidence supporting the idea that the output fluctuations in MENA region are mostly permanent. These results also emphasize that the effectiveness of stabilization policies aimed at real output by the government should be reviewed to achieve long-lasting results.
- MakaleYalnız künye2014Antioxidant and antimicrobial activities of pomegranate (Punica granatum L.) sour sauce extracts
Yildiz, Hilal; Sengul, Memnune; Cetin, Bulent; Karatas, Neva; Ercisli, Sezai; Okcu, Zuhal; Dzubur, Ahmed; Hadziabulic, Semina
In this study, nine-pomegranate sour sauce (PSS) obtained from market in Turkey was tested for their total phenolic content (TPC), antioxidant and antimicrobial activity and selected physico-chemical properties. Methanolwater extracts of PSS were found more effective than water extracts against microorganisms. In particular, Pseudomonas pseudoalkaligenes BC3445 and Staphylococcus aureus ATCC 29213 showed the greatest sensitivity to the extracts. Total soluble solids, total sugar, reducing sugar, sucrose, ash, pH, titratable acidity, colour (L, a, b) of PSS were determined between 69.5-73.3° Brix, 21.89-53.44 g/100 g, 20.97-50.62 g/100 g, 0.75-2.81 g/100 g, 0.05-0.58 g/100g, 2.64-2.91, 4.30-7.97, 16.58-55.38, (+3.94)-(+38.54), (-6.98)-(-38.36). β-carotene bleaching assay indicated that PSS possessed considerable antioxidantactivities. The higher antioxidant capacities of PSS implied that they might be potential resources for the development of functional food.
- MakaleAçık Erişim2014Estimating aboveground biomass using landsat TM imagery: A case study of Anatolian Crimean pine forests in Turkey
Günlü, A.; Ercanli, İ.; Başkent, E.Z.; Çakır, G.
Forests play an important role in carbon circulation, and the productivity of forest ecosystems can be evaluated by evaluating its biomass. Evaluation of biomass aids the determination and understanding of changes in forest ecosystems. Because of the limitations of ground measurements of biomass, in recent times, satellite images have been broadly applied to estimate aboveground biomass (AGB). The objective of this study is to examine the relationships between AGB and individual band reflectance values and ten Vegetation Indices (VIs) obtained from a Landsat TM satellite image for a Anatolian pine forests in northwestern Turkey. Multiple regression analysis is utilized to predict the AGB. The AGB model using TM 1 and TM 2 had an adjusted R2of 0.465. Another AGB model using Enhanced Vegetation Index (EVI) and Normalized Difference 57 (ND57) had an adjusted R2 of 0.606. Our results reveal that VIs present better estimation of AGB in Anatolian pine forests as compared to individual band reflectance values.
- MakaleYalnız künye2014The performance of alternative refrigerant gas R152a as Mobile air conditioning refrigerant
Bilen, Kadir; Kalkisim, Ahmet T.; Solmus, Ismail; Yong, J.Y.; Liew, P.Y.; Klemes, J.J.; Varbanov, P.S.
In this study, the possible alternative replacement of R134a with R152 in the air conditioning (AC) system of an automobile has been investigated theoretically. The properties of the R152a is presented and compared with three different refrigerants (R134a, R22 and R12). At a constant condenser temperature, the effect of evaporator temperature (Te=-20 °C - 0 °C) and compressor speed (n = 600 - 2,000 rpm) on the cooling load, the condenser heat load, compressor work, the mass flow rate of refrigerant and performance coefficient of the AC system have been examined with the help of a commercial computer program for refrigerants investigated. It was found that R152a and R134a do not lead to any significant difference on the performance of the refrigeration system. This result shows that with small modifications on the AC systems of current automobiles commonly using R134a, R-152a can be used as an alternative refrigerant since their compression ratios are almost the same.
- BildiriYalnız künye2014A new approach stereo based palmprint extraction in unrestricted postures
Bingol, Ozkan; Ekinci, Murat; Gokdogan, Ahmet
Regarding the palms recognition system studies, despite achieving a high success rate, hygiene problems in systems with contact and problems arising from changes in the alignment of the hand pose in non-contact ones have been encountered. To resolve these problems, 3D palmprint recognition systems have been developed, however these systems have not had the opportunity to spread due to expensive technologies used as well as low screening rates. In this study, to calculate the position and orientation of a palm in 3D space, a stereo camera system is proposed, with the help of these values by adjusting the geometric image of the palm is converted to a 2D environment. From these images, patterns used for recognition are extracted by using Active Appearance Models. Thus a non-contact system has been achieved, but also patterns that can be used by powerful 2D recognition systems have also been produced.