Yazar "Ava, Canan Aytuğ" seçeneğine göre listele

Listeleniyor 1 - 10 / 10
  • Küçük Resim
    Öğe
    Biosynthesis, characterization, and investigation of antimicrobial and cytotoxic activities of silver nanoparticles using Solanum tuberosum peel aqueous extract
    (Elsevier Ltd., 2023) Xu, Jiajun; Yıldıztekin, Mahmut; Han, Dayong; Keskin, Cumali; Baran, Ayşe; Baran, Mehmet Fırat; Ava, Canan Aytuğ; Kandemir, Sevgi İrtegün
    Metallic nanoparticle biosynthesis is thought to offer opportunities for a wide range of biological uses. The green process of turning biological waste into utilizable products gaining attention due to its economical and eco-friendly approach in recent years. This study reported the ability of Solanum tuberosum (ST) peel extract to the green synthesis of non-toxic, stable, small-sized silver nanoparticles without any toxic reducing agent utilizing the phytochemical components present in its structure. UV–visible spectroscopy, X-ray diffraction analysis, Fourier transform infrared spectroscopy, flourier scanning electron microscopy, atomic force microscopy, transmission electron microscopy, and energy dispersive analysis X-ray confirmed the biosynthesis and characterization of silver nanoparticles. Also, dynamic light scattering and thermogravimetric analyses showed stable synthesized nanoparticles. The antibacterial activity of the biosynthesized silver nanoparticles was evaluated against four different bacterial strains, Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa), Staphylococcus aureus (S. aureus) Bacillus subtilis (B. subtilis), and a yeast, Candida albicans (C. albicans) using the minimum inhibitory concentration technique. The cytotoxic activities were determined against Human dermal fibroblast (HDF), glioblastoma (U118), colorectal adenocarcinoma (CaCo-2), and human ovarian (Skov-3) cell lines cancer cells using MTT test. The nanoparticle capping agents that could be involved in the reduction of silver ions to Ag NPs and their stabilization was identified using FTIR. Nanoparticles were spherical in shape and had a size ranging from 3.91 to 27.07 nm, showed crystalline nature, good stability (−31.3 mV), and the presence of capping agents. ST-Ag NPs significantly decreased the growth of bacterial strains after treatment. The in vitro analysis showed that the ST-Ag NPs demonstrated dose-dependent cytotoxicity against cell lines. Based on the data, it is feasible to infer that biogenic Ag NPs were capped with functional groups and demonstrated considerable potential as antibacterial and anticancer agents for biomedical and industrial applications.
  • [ X ]
    Öğe
    CHARACTERIZATION OF CU2MNSNS4 THIN FILMS FABRICATED BY SPIN COATING
    (2022) Ava, Canan Aytuğ; Baturay, Şilan
    Cu2MnSnS4 (CMTS) thin films are affected by several parameters related to different annealing including sulphur flux rate. In this paper, nontoxic CMTS samples were fabricated onto a soda glass lime substrate by spin-coating to investigate the effect of various sulphur flux rates on the crystal, topological and optical properties by using X-Ray diffraction, scanning electron microscopy, atomic force microscopy, and ultraviolet-visible spectrophotometer, respectively. The X-ray diffraction pattern showed that CMTS films had a main (112) oriented peak and crystallized in a stannite structure. The crystal parameters of CMTS thin films were changed depending on the increase of sulphur flux rate annealed at 550 °C for 90 minutes. The minimum value of dislocation value for CMTS film annealed 30 sccm sulphur flux rate showed the better crystallinity of the film. The scanning electron microscopy images of films showed a decrease in the particle size related to the increased flux of sulphur. AFM images showed that CMTS samples annealed at 40 sccm H2S: Ar had some clumping in the surface topology while CMTS samples annealed at 30 sccm H2S: Ar thin films were uniformly distributed. Ultraviolet-visible spectroscopy (Uv-vis) measurements of the thin films revealed that CMTS film absorbed a high amount of photons as the sulphur flux increased. The energy band gap for the CMTS films was 1.22 and 1.15 eV for 30 sccm and 40 sccm H2S: Ar, respectively. This work showed that different sulphur flux has a significant effect on the structural and morphological properties of CMTS thin films.
  • Küçük Resim
    Öğe
    Cu2Zn(Sn:Ge)S4 ve Cu2Zn(Sn:Si)S4 soğurucu ince filmlerin üretilmesi ve karakterizasyonu
    (Dicle Üniversitesi, Fen Bilimleri Enstitüsü, 2023) Ava, Canan Aytuğ; Asubay, Sezai
    Fotovoltaikler güneş enerjisini doğrudan elektrik enerjisine dönüştüren aygıtlardır. Bu dönüşüm sayesinde güneş pili çalışmaları hız kazanmıştır ancak güneş pilleri ile üretilen elektrik üretimin maliyetinin yüksek olması ince film yarıiletkenlerin kullanılmasını arttırmıştır. İnce filmler, atom veya molekülün, kaplanacağı yüzeye ayrı ayrı dizilerek birkaç ?m kalınlığında oluşan filmlerdir. Son zamanlarda, kalkojen ince filmlere kıyasla, doğada bol bulunması, toksik malzeme içermemesi 1.4-1.5 eV direkt bant aralığına ve 104 cm-1 gibi yüksek bir soğurma katsayısına sahip olmasından dolayı CZTS ince filmleri tercih edilmektedir. Bu çalışmanın amacı CZTS ince filmleri üretilirken (özellikle Sn yerine) yeni elementlerin etkisini deneysel ve teorik olarak ele alıp detaylı incelemektir. Yapılan çalışmada, Sn atomlarını Si ve Ge atomları ile yer değiştirmemizdeki amaç Cu2Zn(Sn:Si)S4 ve Cu2Zn(Sn:Ge)S4'deki üretim maliyetini azaltmak ve ışığın absorbsiyonunu artırmaktır. Cu2Zn(Sn:Si)S4 ve Cu2Zn(Sn:Ge)S4 ince filmleri PV sistemlerde daha etkin kullanılabilmesi amacıyla, dönel kaplama yöntemi ile Cu2Zn(Sn:Si)S4 ve Cu2Zn(Sn:Ge)S4 filmleri camlar üzerine oluşturulmuştur. Farklı ikame oranları (x=0, 0,25, 0,50, 0,75 ve 1) ve farklı H2S (30 ve 40 ccm) oranları ile oluşturulan Cu2Zn(Sn:Si)S4 ve Cu2Zn(Sn:Ge)S4 ince filmlerin yapısal, morfolojik ve optik özelliklerinin, üretim koşullarına bağlı değişimleri incelenmiştir. Oluşturulan ince filmlerin optik özellikleri ultraviyole ve görünür ışık absorbsiyon spektroskopisi (UV-VIS), yapısal özellikleri X ışını kırınımı (XRD) ve Raman spektroskopisi, morfolojik özellikleri ise Taramalı elektron mikroskobu (SEM), ve Atomik kuvvet mikroskobu (AFM) ile araştırılmıştır. Yapılan çalışmada, Ge'nin CZTS yapısına ikamesi ile filmlerin kristal boyutunun 32.15 ve 33.53 nm'den 15.67 ve 22.82 nm'ye düştüğü, daha fazla Ge ikamesinden sonra Cu2ZnGeS4 ince filmler için 36.39 ve 28.34 nm'ye kadar arttığı, ayrıca Cu2ZnGeS4 ince filmlerinin dislokasyon yoğunluğunun ve mikro gerinim değerlerinin ters özellikte olduğu belirlenmiştir. Örneklerin Raman spektrumları, yapılara Ge içeriği ekleyerek mavi kaymalı kesterit yapıların oluşumunu kanıtlamıştır. SEM görüntüleri, 30 ccm Ar:H2S akışı altında tavlanan film yüzeylerinin 40 ccm Ar:H2S akışı altında tavlanan film yüzeyine göre daha homojen olduğunu göstermiştir. SEM görüntülerinden elde edilen bulgular AFM görüntüleri ile doğrulanmıştır. CZTS ince filmlerinin optik bant aralığının Ge içeriği ile 1.53 eV'den 2.05 eV'ye yükseldiği görülmüştür. Si'nin CZTS yapısına ikamesi, XRD analizinde pikin ana tepe noktasında 28.52°'den 28.61°'ye bir kayma ile sonuçlandığını ve merkezin kristal boyutunu keskin bir şekilde azaltarak hem dislokasyon yoğunluğunu hem de gerinim değerlerini arttırdığını göstermiştir. Ayrıca Raman spektrumları ile ikincil fazların olmadığı da gözlemlenmiştir. SEM görüntülerinde, Cu2ZnSnS4 ve Cu2ZnSiS4 kristalitlerinin, ince film numunelerinin yüzeyi boyunca üniform olarak dağıldığı görülmüştür. Ayrıca Cu2ZnSiS4 örneğinin yüzeyinde, Cu2ZnSnS4 yüzeyine göre çok daha fazla ve küçük aglomerasyon olduğu belirlenmiştir. UV-vis ölçümleri, CZTS yapısındaki Si içeriğinin artmasıyla optik bant aralığında 1.51'den 3.22 eV'ye doğru bir artış ortaya çıkarmıştır. Sonuçlar, CZTS ince filmlerinin optik bant aralığının, herhangi bir ikincil faz elde etmeden yapıya Si ikamesi ile değiştirilebileceğini göstermiştir. Çalışma sonucunda, geleneksel CZTS yapılarına kıyasla Si ve Ge ikamesinin, daha yüksek bant aralıklı yarı iletkene ihtiyaç duyan çeşitli uygulamalarda kullanılabileceği gösterilmiştir.
  • [ X ]
    Öğe
    CuMnO2 Filmlerini Yapısal ve Optik Özellikleri Üzerinde Tabaka Kalınlığının Etkisi
    (2022) Baturay, Şilan; Ava, Canan Aytuğ
    Çalışmada, farklı tabaka kalınlıklarda mezogözenekli CuMnO2 ince filmler dönel kaplama tekniği kullanılarak cam alttaş üzerine biriktirilmiştir. Elde edilen örneklerin fiziksel özellikleri X-ışını kırınımı (XRD), taramalı elektron mikroskopu (SEM), atomik kuvvet mikroskopu (AFM) ve UV-Vis ölçüm sistemi kullanılarak incelenmiştir. XRD analizi kullanılarak örneklerin mikro yapı, stres değeri, kristal büyüklüğü ve dislokasyon yoğunluğu hesaplandı. SEM görüntüleri elde edilen örneklerin küresele benzer nanoyapıların oluştuğunu ve nanoparçacıkların sayısının kalınlığa bağlı olarak arttığı göstermektedir. SEM görüntülerinden elde edilen yüzey özellikleri AFM görüntüleri ile doğrulanmaktadır. FEI Quanta 250 FEG taramalı electron mikroskopu (SEM) ile örneklerin tabaka kalınlığı yaklaşık olarak CuMnO2(I) için 157, CuMnO2(II) için 684 ve CuMnO2 (III) için 935 nm civarında ölçülmüştür. Örneklerin enerji bant aralığı ve soğurma değerleri 300-1100 nm aralığında UV-vis cihazı kullanılarak analiz edildi. Örneklerin soğurma değeri filmin kalınlığının artışına bağlı olarak değişmiştir. Enerji bant aralığı değeri ise, kalınlığın değişimine bağlı olarak radikal bir şekilde 1.78'den 1.92 eV'ye artmıştır.
  • Küçük Resim
    Öğe
    The influence of Ge substitution and H2S annealing on Cu2ZnSnS4 thin films
    (Elsevier, 2021) Ava, Canan Aytuğ; Ocak, Yusuf Selim; Asubay, Sezai; Çelik, Ömer
    Cu2Zn(Sn1-xGex)S-4 thin films (where x = 0, 0.25, 0.50, 0.75, and 1) were deposited by spin coating technique and annealed under 30 and 40 ccm H2S:Ar (1:9) flows to understand the influence of Ge atom content ratio and H2S flow rate during the annealing of thin films on morphological, structural and optical properties of Cu2Zn(Sn1- x Ge-x)S-4 thin films. It was seen that the Ge content has a strong influence on the structural and optical properties of the films. The crystal size of the films decreased sharply for Cu2Zn(Sn0.75Ge0.25)S-4 thin film and started to increase slowly owing to the formation of high dislocation density and strain in the structures. The Raman spectra show the formation of kesterite thin films and blue Raman shift with Ge substitution to the content. The films obtained under 40 ccm H2S:Ar (1:9) flows have weak secondary peaks associated with ZnS formation. The UV-Vis data showed the increase of optical bandgap from 1.52 to 2.05 eV with a rise in Ge ratio in the structures.
  • [ X ]
    Öğe
    INVESTIGATION OF TEMPERATURE DEPENDENCE OF D2O SOLUTIONS BY 400 MHZ NMR
    (Bilal GÜMÜŞ, 2018) Balcı, Gülten Kavak; Ava, Canan Aytuğ; Yılmaz, Ali
    The rate of water proton relaxation of protein solutions were studied in the presence and absence of the paramagnetic ions[gadolinium (III), manganese (II), chromium (III), iron (III), nickel (II), copper (II), and cobalt (II)]   in the previous studies. However, these studies were carried out rather at low frequencies. Therefore, studying of temperature dependence of relaxation rates for absence and presence of 2 % albumin in pure D2O by 400 MHz will be a novelty. In this study, T1 and T2 relaxation ratios of D2O and 0.1 H2O/0.9D2O solutions were investigated with respect to temperature for pure and  for constant  albumin  concentration(2%). The experiments were carried out by using Bruker Avance 400 MHz NMR. Inversion Recovery (180-?-90) pulse step were used for T1, whereas Carr-Purcell-Meiboom-Gill pulse step were used for T2.  The experiments were performed for temperature range of 20°C-40°C by using automatic temperature control unit. 1/T1 and 1/T2 decrease linearly with increasing temperature for pure D2O solutions. However, for 0.1H2O/0.9D2O solutions, the relaxation rates of T1 increase with increasing temperature while T2 decreases with increasing temperature. The decrease in both relaxation rates of the D2O solution with respect to the increased temperature suggests that relaxation is due to spin relaxation interaction. Increasing of relaxation rates with the increasing temperature, in the presence of albumin demonstrates the validity of the dipolar mechanism
  • Küçük Resim
    Öğe
    The investigation of the chemical composition and applicability of gold nanoparticles synthesized with amygdalus communis (Almond) leaf aqueous extract as antimicrobial and anticancer agents
    (MDPI, 2023) Baran, Mehmet Fırat; Keskin, Cumali; Baran, Ayşe; Eftekhari, Aziz; Omarova, Sabina; Khalilov, Rovshan; Ava, Canan Aytuğ
    The current work’s main objective was to determine the chemical composition of Amygdalus communis (AC) leaf extract and examine the antibacterial and cytotoxic properties of biosynthesized gold nanoparticles (AuNPs). The chemical composition of AC leaf extract was determined using LC-ESI/MS/MS to detect compounds that may be responsible for the reducing, stabilizing, and capping steps in the synthesis of nanoparticles and their biological activities. The AC-AuNPs were spherical, with a particle size lower than 100 nm and a face-centered cubic structure. The EDX spectrum confirmed the formation of AuNPs and a negative zeta potential value (−27.7 mV) suggested their physicochemical stability. The in vitro cytotoxic efficacy of the AC-AuNPs against colorectal adenocarcinoma (Caco-2), glioma (U118), and ovarian (Skov-3) cancer cell lines and human dermal fibroblasts (HDFs) was evaluated by MTT assay. CaCo-2 cell proliferation was effectively inhibited by the AC-AuNPs at concentrations between 25 and 100 g mL−1. The AC-AuNPs exerted preeminent antimicrobial activity against Bacillus subtilis with an MIC of 0.02 μg/mL, whilst good activity was shown against Staphylococcus aureus bacteria and Candida albicans yeast with an MIC of 0.12 μg/mL. Ultimately, the results support the high antibacterial and anticancer potential of biosynthesized AuNPs from AC leaf extract.
  • Küçük Resim
    Öğe
    Investigation of the structural and morphological features of TiO2:8OBA composites for MIS semiconductor diodes
    (Elsevier Ltd, 2023) Güllü, Ömer; Okumuş, Mustafa; Ava, Canan Aytuğ
    In this study, a liquid crystal 8OBA-doped TiO2 composite was formed on a p-Si substrate using the ultrasonic spray coating method. The characterization of the un-doped and doped films produced was carried out by SEM-EDS, XRD and UV–vis measurements. SEM/EDS analysis showed that the TiO2:8OBA composite completed the formation of a layer on the glass surface and exhibited a homogeneous distribution throughout the surface. XRD analysis of TiO2:8OBA composites showed that anatase and rutile crystal phases are belonging to TiO2 and C[sbnd]H based phase indicating 8OBA. In addition, as a result of UV–vis analysis, the optical band gap of 8OBA:TiO2 composite was calculated as 2.82 eV. Besides, the diode application of 8OBA doped and un-doped TiO2 thin film was performed. Charge transport processes of the diode were studied in detail by taking current–voltage measurements. The ideality factor, barrier height, series resistance and parallel resistance values were extracted using different methods.
  • Küçük Resim
    Öğe
    Optical and morphological properties of Cu2FeSnS4 chalcogenide films
    (Yüzüncü Yıl Üniversitesi Fen Bilimleri Enstitüsü, 2023) Ava, Canan Aytuğ; Baturay, Şilan
    Abstract: P-type Cu2FeSnS4 (CFTS) and Cu2ZnSnS4 (CZTS) quaternary chalcogenide films have been grown by the method of spin coating on glass substrates relate to 30 and 40 sccm sulfur flux. Physical properties of obtained samples were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and ultraviolet visible spectroscopy (UV-Vis) to see the effect of deposition parameters on the thin film. The crystal parameters including crystal size, dislocation density and strain value of the samples were changed related to the deposition parameters. XRD results indicated an improvement of the crystalline quality of quaternary chalcogenide CFTS with a maximum crystal size of about 50 nm for (112) peak orientation. SEM images illustrated that the particle size was changed with an increase in the flux of sulfur, which was confirmed with both XRD and AFM images. It was seen that the absorption and energy band gap value of the samples changed the effect of sulfur flux and CZTS film for 40 sccm exhibited more strong absorption all samples in the UV-Vis region. The band gap values of the samples were calculated 1.51, 1.53, 1.82 and 1.91 eV for CZTS (30 sccm), CZTS (40 sccm), CFTS (30 sccm) and CFTS (40 sccm) films annealed H2S gas, respectively.
  • Küçük Resim
    Öğe
    Structural and electronic characterization of silicon based MIS contact by xanthene dye molecules (Erythrosine B)
    (Elsevier B.V., 2023) Sunkur, Murat; Ava, Canan Aytuğ; Güllü, Ömer
    The effect of erythrosine B (ERY) organic material as an interface layer on the electronic characteristics of the Al/p-Si junction is examined in the present work. AFM, NMR, UV–Vis and FTIR measurements have been conducted on the ERY dye molecule. The ERY film on the surface of the substrate is coated with nanoparticles, according to the surface analysis performed using the AFM technique. The basic diode parameters of Al/p-Si and Al/ERY/p-Si junctions were measured by utilizing current-voltage (I–V) and capacitance-voltage (C-V) techniques. The junctions with and without organic interfacial layers were found to have ideality factors of 1.931 and 1.925, respectively. For MS and MIS contacts, the estimated values of barrier height were 0.592 eV and 0.937 eV, respectively. Additionally, the series resistances for the MS and MIS structures by utilizing Norde function, were determined to be 0.14 kΩ and 322.85 kΩ, respectively. In addition, the reverse bias 1/C2-V characteristics were used to analyze the barrier height values and compare the findings to those from I-V method. The experimental findings demonstrated that the Al/ERY/p-Si MIS diode has a barrier height that is remarkably greater than that of the reference Al/p-Si junction. Placement of the ERY dye interlayer between a metal and a semiconductor could enhance and regulate the performance and characteristic of these types of junctions.