Arama Sonuçları

Listeleniyor 1 - 10 / 13
  • Öğe
    Docking and molecular dynamics calculations of some previously studied and newly designed ligands to catalytic core domain of HIV-1 integrase and an investigation to effects of conformational changes of protein on docking results
    (Türkiye Kimya Derneği, 2017-01-09) Ercan, Selami
    Nowadays, AIDS still remains as a worldwide pandemic and continues to cause many deaths which arise from HIV-1 virus. For nearly 35 years, drugs that target various steps of virus life cycle have been developed. HIV-1 integrase constitutes one of these steps which is essential for virus life cycle. Computer-aided drug design is being used in many drug development and drug improvement studies as also used in development of the first HIV-1 integrase inhibitor Raltegravir. In this study, 3 ligands which are already used as HIV-1 integrase inhibitors and 4 newly designed ligands were docked to catalytic core domain of HIV-1 integrase. Each ligand docked to three different conformations of protein. Prepared complexes (21 items) were carried out by 50 ns MD simulations and results were analyzed. Finally, the binding free energies of ligands were calculated. It was determined that designed ligands L01 and L03 gave favorable results. The questions about the ligands which have low docking scores in a conformation of protein could give better scores in another conformation of protein and if the MD simulations carry the different oriented and different localized ligands in same position at the end of simulation were answered.
  • Öğe
    Experimental investigation of solar stills integrated with solar water heating collectors
    (Türk Isı Bilimi ve Tekniği Derneği, 2017-10-31) Argunhan, Zeki; El, Emin; Yıldız, Cengiz; Çakmak, Gülşah
    Solar still is a more practical way of obtaining clean water. In this study, we aimed to improve the efficiency of solar still systems and obtain distilled water at the same time. For this purpose, 5 different solar still systems were designed. Type 1; conventional solar still, Type 2; conventional solar still integrated with solar water heating collector and run via natural convection, Type 3; conventional solar still integrated with solar water heating collector and tubular heat exchanger and run via natural convection, Type 4; conventional solar still placed with plate heat exchanger and integrated with solar water heating collector and run via natural convection, Type 5; conventional solar still placed with plate heat exchanger and integrated with solar water heating collector and run via forced convection. In this study, the experiments were carried out on the parameters influencing the performance, the amount of distilled water obtained, and the efficiency of experiment settings designed in different types; and finally the results were presented. The amount of distilled water and efficiency of conventional solar still were 2389 ml and 51.47%, respectively. Maximum total amount of water and efficiency from natural convection systems were obtained from Type 4, and the values calculated were found as to be 5788 ml and 55.91%. Maximum amount of distilled water and the efficiency were obtained by utilizing forced convection system were found as to be 6068 ml and 58.99%, respectively.
  • Öğe
    Design, preparation and application of a Pirkle-type chiral stationary phase for enantioseparation of some racemic organic acids and molecular dynamics studies
    (ACG Publications, 2017-11) Çakmak, Reşit; Ercan, Selami; Sünkür, Murat; Yılmaz, Hayrullah; Topal, Giray
    This study consists of two parts. In the first part of the study; a Pirkle-type chiral stationary phase was prepared by synthesizing an aromatic amine derivative of (R)-2-amino-1-butanol as a chiral selector and binding to L-tyrosine-modified cyanogen bromide (CNBr)-activated Sepharose 4B and then, packed into the separation column. The chromatographic performance of the separation column was evaluated with racemic mandelic acid and 2-phenylpropionic acid by using phosphate buffers at three different pHs as mobile phase. In the resolution processes, the prepared solutions were loaded onto the separation column at two different concentrations and at three different pHs for each racemic organic acid, separately. Enantiomeric excess (ee%) of the eluates was determined on CHIRALPAK AD-H chiral analytical column by HPLC. The maximum ee% for mandelic acid and 2-phenylpropionic acid was determined to be 60.84 and 27.4, respectively. Separation factors (k1 ’ , k2 ’ , α, and Rs) were calculated for each acid. The structures of the obtained compounds were characterized using the spectroscopic methods (NMR, and elemental analysis). In the second part of the study; enantioselective interactions between the prepared CSP and the analytes have been widely studied by docking, molecular dynamics simulation and quantum mechanical computation methods. The reason of column eluation of rac-2-phenylpropionic acid with lower enantiomeric yield was explained by these techniques.
  • Öğe
    Tabakalı hibrit kompozit malzemelerin yorulma davranışlarının analizi
    (Tüm Bilim İnsanları ve Akademisyenler Derneği, 2019-09-30) Topkaya, Tolga; Solmaz, Murat Yavuz; İmak, Anıl
    Endüstride geniş kullanım alanına sahip tabakalı kompozit malzemeler, kullanıldıkları alanlara bağlı olarak tekrarlı yüklere maruz kalabilmektedirler. Bu nedenle malzemelerin tekrarlı yüklere karşı dayanımı önemli bir parametredir. İzotropik malzemelerden farklı olarak kompozit malzemelerin yorulma davranışlarının tespiti daha zordur. Bunun sebebi kompozit malzemelerin tasarımı sırasında ele alınan parametrelerin sayısının fazlalığıdır. Gerçekleştirilen bu çalışmada tabakalı hibrit kompozit malzemelerin yorulma davranışları deneysel olarak incelenmiştir. Çalışmada karbon ve cam olmak üzere üç farklı hibrit numune elle yatırma yöntemi ile epoksi reçine kullanılarak üretilmiştir. Elyafların reçine ile birleştirilmesinin ardından kompozit levhalara hidrolik sıcak pres uygulanmıştır. Yorulma deneylerinin yapılabilmesi için gerekli olan numuneler ASTM standartlarına uygun şekilde boyutlandırılmıştır. Deneyler sırasında gerilme oranı 0.1 ve frekans 10 Hz seçilmiştir. Deney sonucunda elde edilen sonuçlar karşılaştırmalı olarak grafikler halinde sunulmuştur.
  • Öğe
    Electronic properties of Cu/n-InP metal-semiconductor structures with cytosine biopolymer
    (Polska Akademia Nauk, 2015-09) Güllü, Ömer; Türüt, Abdülmecit
    This work shows that cytosine biomolecules can control the electrical characteristics of conventional Cu/n-InP metal-semiconductor contacts. A new Cu/n-InP Schottky junction with cytosine interlayer has been formed by using a drop cast process. The current-voltage (I-V) and capacitance-voltage (C-V) characteristics of Cu/cytosine/n-InP structure were investigated at room temperature. A potential barrier height as high as 0.68 eV has been achieved for Cu/cytosine/n-InP Schottky diodes, which have good I-V characteristics. This good performance is attributed to the effect of interfacial biofilm between Cu and n-InP. By using C-V measurement of the Cu/cytosine/n-InP Schottky diode the diffusion potential and the barrier height have been calculated as a function of frequency. Also, the interface-state density of the Cu/cytosine/n-InP diode was found to vary from 2:24 × 1013 eV-1cm-2 to 5.56× 1012 eV-1 cm-2.
  • Öğe
    Characterization of an Early Bronze Age pottery group from the upper Tigris valley (Turkey) by means of spectroscopic and microscopic techniques
    (X-RAY Spectrometry, 2019-04-17) Kozbe, Gülriz; Bayazıt, Murat
    In this archaeometric research potsherds from Kavuşan Höyük (a mound located in the upper Tigris valley) representing the Metallic Ware, a diagnostic ceramic group mostly found in north Mesopotamia was characterized using spectroscopic and microscopic techniques in order to differ the imitated ones, if exist, to reveal the production technologies and compare the results with the previous archaeometric works concerning Metallic Ware. For this purpose, optical microscopy, scanning electron microscopy equipped with energy dispersive spectroscopy, polarized energy dispersive X-ray fluorescence, X-ray diffraction, and micro-Raman spectroscopy were used. Two groups were specified as the calcareous “imitations” and the dominant noncalcareous ware as the real ones. The results suggested that the noncalcareous ware of Kavuşan was presumably not produced with the possible clay deposits mentioned in previous studies, which focused on the provenance investigation of a wide range of Metallic Ware samples from the upper Tigris valley. It was also concluded from the results that the calcareous imitations would presumably belong to a local (in the name of Kavuşan) or regional (the upper Tigris) production due to the geological and chemical affinities.
  • Öğe
    A fuzzy logic based approach to solve interval multiobjective nonlinear transportation problem
    (Springer Nature, 2019-06-01) Dalman, Hasan; Sivri, Mustafa
    This paper presents the solution procedure of multiobjective nonlinear transportation problem (MNOTP) where the cost coefficients of the objective functions, and the supply and the unknown demand parameters have been formulated as interval numbers by the decision maker. This problem has been converted into a conventional MNOTP where to minimize the interval nonlinear objective functions, the order relations that define the choice between intervals have been determined by the interval arithmetic. Also, the constraints with interval supply and unknown demand parameters have been transformed into its deterministic forms. Then the deterministic problems have been solved by two compromise programming methods. Finally, a numerical example is presented to illustrate the efficiency of the proposed procedure as well.
  • Öğe
    On solving partial differential eqauations of fractional order by using the variational iteration method and multivariate padé approximation
    (European Journal of Pure and Applied Mathematics, 2013-04) Turut, Veyis; Güzel, Nuran
    In this article, multivariate Padé approximation and variational iteration method proposed by He is adopted for solving linear and nonlinear fractional partial differential equations. The fractional derivatives are described in the Caputo sense. Numerical illustrations that include nonlinear timefractional hyperbolic equation and linear fractional Klein-Gordon equation are investigated to show efficiency of multivariate Padé approximation. Comparison of the results obtained by the variational iteration method with those obtained by multivariate Padé approximation reveals that the present methods are very effective and convenient.
  • Öğe
    Effect of the air flow rate of blower on the performance of solar still
    (Türk Isı Bilimi ve Tekniği Derneği, 2015-06-01) Argunhan, Zeki; El, Emin; Yücel, Halit Lutfi; Çakmak, Gülşah; Yıldız, Cengiz
    Solar distillation is one of the important methods for water purification. This paper examines the performance of solar distillation system at different air flow rate. To increase the performance of distiller, artificial wind was created by fan and suitable wind speed was investigated to increase the amount of water distilled. The experiments were carried out in Elazığ climate conditions. In order to examine the effect of the wind speed on solar distillation system, two stills were manufactured with the size of 1000x1000 mm. One of them was the conventional still which was used as a reference. The other still was used to investigate experimentally the effect of the wind speed. Graphs were drawn for time-dependent changes in the amount of water distilled. It was found that that the productivity of the fan-still distiller was 14.7 % greater than that of a conventional still.
  • Öğe
    Extraction of lanthanum and cerium from a bastnasite ore by direct acidic leaching
    (TMMOB Maden Mühendisleri Odası, 2020-06-01) Özsaraç, Şafak; Kurşunoğlu, Sait; Hussaini, Shokrullah; Gökçen, Hasan Serkan; Kaya, Muammer; Altıner, Mahmut; Top, Soner
    The extraction of lanthanum (La) and cerium (Ce) from a bastnasite ore by direct acidic leaching was investigated. The effects of acid concentration and leaching temperature on the extraction of La and Ce from the ore were tested. Using nitric (NHO3 ), more than 85% of the La and Ce were simultaneously extracted into leach solution whereas the La and Ce dissolutions were determined as less than 85% by using sulfuric acid (H2 SO4 ). The La dissolution exceeded 90% by using hydrochloric acid (HCl); however, the Ce dissolution remained below 85% under the following conditions: solid-to-liquid ratio of 20% (w/v), the acid concentration of 20%, leaching temperature of 25 °C and leaching time of 1 h. The result revealed that HNO3 could be used as a solvent for the maximum simultaneous extraction of the La and Ce from the bastnasite ore. The leaching temperature had no crucial effect on the dissolution of La and Ce when HNO3 or HCl solutions were preferred as a solvating agent. However, the leaching temperature had a slight positive effect on the dissolutions of La and Ce when H2 SO4 was used as a solvent.