Sürdürülebilir Kalkınma Amaçları
Yayınlar
- MakaleAçık Erişim2024Scopus SJRQ3Structural, Dielectric, and Electrical Properties of Chitosan Composites Doped with Silver for Electrochemical Applications
Ayhan, Nagihan Karaaslan; Torgut, Gulben
In this study, chitosan-silver (Chs-Ag) composites containing Ag in different concentrations (0.01–0.08 M) were prepared. The characterization and structure studies of the composites containing 0.01, 0.02, 0.04, and 0.08 M Ag were carried out, and then the dielectric properties of these composites were examined. The composites were characterized by Fourier transform infrared spectrophotometer (FTIR), scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS), and thermogravimetric analysis (TGA). The dielectric and electrical properties of these composites were investigated depending on the frequency at room temperature, and these properties were determined using an impedance analyzer. Spectroscopy revealed that the dielectric constant (ε′), dielectric loss (ε′′), and real (Z′) and imaginary (Z″) components of impedance are found to decrease with increased frequency for both Chs and Chs-Ag (0.01M–0.08 M) composites. On the contrary, the AC conductivity (σac) of samples increased with increasing frequency. ε′ and ε′′ values of Chs were lower than when the Ag was added. The AC conductivity was improved by the addition of silver particles. The results show that the dielectric and electrical properties of Chs-Ag samples were improved by using Ag as filler.
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İncele - MakaleYalnız künye2023Scopus SJRQ1Improving dielectric properties, electrical conductivity, and thermal properties of biodegradable polymer composites prepared with lanthanum
Torgut, Gulben; Ayhan, Nagihan Karaaslan; Acikses, Aslisah
The precipitation method was adapted to synthesize the poly(ε-caprolactone-copolymer- ethylene oxide) (ε-CL-co-EO) composite with the salt of lanthanum (La), a rare earth element. This salt was incorporated into the polymer of different weight percentages to study how it affects the thermal and dielectric properties of the polymer. The resulting products were characterized by Fourier Transform Infrared Spectroscopy, X-ray diffractometry (XRD), Scanning electron microscopy (SEM) and thermogravimetric analysis. XRD and SEM data show that the polymer mixes homogeneously with the metal salt. Thermal degradation data show that the thermal stability of composites synthesized with La is lower than that of pure polymer. The dielectric properties and A.C conductivity measurements of the composites were investigated by using impedance analyzer in the frequency range (100 Hz to 20 kHz) at room temperature. The electrical property results of (ε-CL-co-EO)/La composites displayed that dielectric constant (έ), dielectric loss (ε"), tan delta (tan δ) and A.C electrical conductivity (σac) increase with increasing La content. The largest conductivity of (ε-CL-co-EO)/La composite filled with 20 wt% La was 8.80 × 10−8 S/cm, which was 162% times pure (ε-CL-co-EO). In addition, impedance (IZI) of composites was evaluated from the dielectric data. This procedure is eco-friendly and easy to handle, which provides a promising route to polymer composites in the application of the conductivity field.
AtıfScopus6WoS6OpenAlex7İncele - MakaleYalnız künye2023Scopus SJRQ2Antibacterial activity of novel synthesized chitosan-graft-poly(N-tertiary butylacrylamide)/neodymium composites for biomedical application
Yazdıç, Ferit Can; Karaman, Altuğ; Torğut, Gülben; Ayhan, Nagihan Karaaslan
In this present study, composites of chitosan-graft-poly(N-tertiary butylacrylamide) (CH-graft-poly(N‑tert‑BAAm)) copolymer, with Neodymium (Nd), an important rare earth element, were prepared by precipitation technique. Nd was successfully incorporated into the polymer of different weight percentages (0.5%, 1%, and 2%) without any degradation. The effect of neodymium additives on the structural, morphological, and antibacterial activities against gram-positive bacteria and gram-negative bacteria of the polymer was analyzed using various instrument techniques. X-ray diffraction (XRD) results together with Fourier Transform Infrared (FT-IR), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) studies confirmed the morphology of Nd-doped CH-graft-poly(N‑tert‑BAAm) composites without any other impurities. The antibacterial effect of Nd was studied by adding it to the copolymer in a weight ratio of 0.5%–2%. The antibacterial effect of neodymium concentration on four different strains of bacteria was investigated: Escherichia coli (ATCC 25922) (E. coli), Pseudomonas aeruginosa (DSM 50071) (P. aeruginosa), Bacillus subtilis (DSM 1971) (B. subtilis), and Staphylococcus aureus subsp. aureus (ATCC 25923) (S. aureus). The antibacterial activities of the obtained composites were determined using the Agar Well Diffusion Assay Method. Experimental results show that Nd binds well to CH-graft-poly(N‑tert‑BAAm). Activity against E. coli, P. aeruginosa, B. subtilis, and S. aureus subsp. aureus creates a potential for pharmaceutical and biomedical applications.
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İncele - MakaleAçık Erişim2023Scopus SJRQ3The biosorption of Co(II) by Homalothecium sericeum from aqueous solutions under batch conditions: response surface methodology optimization and Daphnia magna bioassay
Tanyol, Mehtap; Korkmaz, Volkan; Yildirim, Numan; Erguven, Gokhan Onder; Ayhan, Nagihan Karaaslan; Alatas, Mevlut
In the present work, Homalothecium sericeum biomass was used for removal of Co(II) from aqueous solution. The effects of process parameters (contact time, biosorbent amount, and initial Co(II) con-centration) on the response (Co(II) % removal) were investigated using a batch adsorption system optimized with response surface methodology/central composite design method. Under optimized conditions the maximum Co(II) removal efficiency achieved is 94.07% at an initial Co(II) concentration of 2.05 mg/L, a H. sericeum amount of 0.34 g/50 mL, and a process time of 36.09 min. In this study, the toxicity of the medium after biosorption carried out under optimized conditions was also tested with Daphnia magna bioassay. When mortality results with D. magna were evaluated, although a removal efficiency of 94.07% was obtained after biosorption, this was not sufficient to reduce mortality of D. magna.
AtıfScopus1WoS2İncele - Derleme MakaleAçık Erişim2021Rare Earth Element Doped ZnO Thin Films and Applications
Ayhan, Nagihan Karaaslan; İpek, Yeliz
In this review, general information has been given about the recent studies on thin film coating techniques, zinc oxide (ZnO) thin films and zinc oxide films doped with rare earth elements (REE). As a thin film coating method, the sol‒gel method is widely used due to its economical nature. However, it has been seen that the magnteron sputter technique is also very popular due to its ease of application. Zinc oxide is a semiconductor with a wide band gap and is easy to produce and to supply. In addition, it does not have negative effects on the environment and human health. All these properties have led to intensive studies on zinc oxide. Due to its optical and electrical properties, it has found many different uses such as solar cells, light emitting diodes, gas sensors and flat panel displays. Recently, various studies have been carried out to improve the properties of zinc oxide and to create new areas of use by doping with rare earth elements.
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İncele - MakaleYayıncıda açık erişim2020Scopus SJRQ4Assessment of elemental content, antioxidant activity, and total phenolic content of vitis sylvestris gmelin
Ayhan, Nagihan Karaaslan
In this study, we determined the Cu, Fe, Mn, and Zn contents of Vitis sylvestris Gmelin using flame atomic absorption spectrometry (FAAS), and examined the antioxidant properties of Vitis sylvestris Gmelin using radical scavenging capacities and total phenolic content tests. We found the average elemental contents; Cu, Fe, Mn, and Zn as 1.506 ± 0.042 mg/kg, 0.796 ± 0.020 mg/kg, 2.333 ± 0.033 mg/kg, and 3.191 ± 0.262 mg/kg, respectively. When we examined the antioxidant activity tests applied to different extracts, we determined the highest extraction yield with the methanol extract. DPPH radical scavenging activity, ABTS radical scavenging activity, and total phenolic content values in methanol extract were determined to be respectively 3.957 ± 0.146 mg TEAC/g fw, 9.062 ± 0.273 mg TEAC/g fw, and 2.365 ± 0.028 mg GAE/g fw. When we evaluated the antioxidant activity and total phenolic content results for all extracts statistically, we determined that there was generally a statistically significant difference between each extract (p < 0.01). Vitis sylvestris Gmelin has high antioxidant content when considering the data obtained. Also, we determined that it is an effective candidate in the protection against reactive oxygen species.
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