Makale Koleksiyonu

Bu koleksiyon için kalıcı URI

https://hdl.handle.net/20.500.12587/18128

Listeleniyor 1 - 20 / 30

Variation of fundamental features of cobalt surface-layered Bi-2212 superconductor materials with diffusion annealing temperature
(Elsevier Sci Ltd, 2023) Öz, İllker; Terzioglu, Cabir; Öz, Muhammed; Ülgen, Asaf Tolga; Türköz, Mustafa Burak; Erdem, Ümit; Yıldırım, Gürcan
The present study appears extensively on the role of diffusion annealing temperature intervals 650-850 degrees C on electrical conductivity, flux pinning ability, superconducting and crystallinity quality of Cobalt (Co) surface -layered Bi-2212 compounds with experimental tests including dc resistivity, bulk density, X-ray diffraction, critical current density measurements, and theoretical calculations. Experimental findings display that the Co ions may be replaced mostly by bismuth sites in the crystal lattice as a consequence of appropriate cation -vacancy, electron configurations of the outer shell, chemical valence states, and electronegativity of chemical contents in the main composition. The fundamental characteristic features refine considerably with 650 degrees C annealing temperature due to enhancement of antiferromagnetic spin fluctuations in the clusters of micro -domains, re-ordering of Cu-O bonds, stabilization of system, pairing mechanism, modulation of insulating Bi-O double layers, and orbital hybridization mechanisms. Accordingly, bulk Bi-2212 ceramic obtained at optimum annealing temperature exhibits the best conductivity because of a decrease in systematic crystallinity problems and potential grain boundary interaction problems expected in the system. Likewise, the optimum annealing temperature triggers the artificial nucleation regions for 2D discrete pancakelike Abrikosov vortices to decelerate thermal fluxon movements. Moreover, the X-ray diffraction results indicate that optimum Co ions in crystal lattice significantly improve crystal structure quality, grain alignment distributions in c-axis orientation, the extension of high-Tc Bi-2223 superconducting phase, and average crystallite size parameters. Additionally, the nucleation activation energy is noticed to reduce with optimum Co ions due to enhancement in the nucleation stability and crystallization temperature values to higher temperature zones. Namely, optimum Co ions easily diffusing into the lattice points support the formation of surface nucleation. In contrast, after a critical value of 650 degrees C, the characteristic properties mentioned suppress remarkably. In conclusion, the main characteristic features are extensively improved by the optimum diffusion annealing temperature for usage in novel and feasible market areas.
Ultrasonographic and histopathological investigation of the effect of N-acetylcysteine on doxorubicin-induced ovarian and uterine toxicity in rats
(Bmc, 2024) Ustuner, Evren; Yildirim, Ebru; Macun, Hasan Ceyhun; Ekici, Hüsamettin; Şahin, Yaşar; Güncüm, Enes; Anteplioğlu, Tuğçe
Background This study aimed to investigate the mitigating effect of N-acetylcysteine (NAC) on doxorubicin (DOX)-induced ovarian and uterine toxicity in rats using laboratory tests, ultrasonographic (US) imaging, and histopathology analysis. Methods Forty-eight rats were divided into six groups (n = 8) as follows: Group A (control) (0.5 mL saline administered intraperitoneally [IP]), Group B (a single 10 mg/kg dose of DOX administered IP on day 1), Group C (a single 10 mg/kg dose of DOX administered IP 24 h before sacrifice), Group D (100 mg/kg of NAC administered IP for 21 days), Group E ( a single 10 mg/kg dose of DOX administered IP on day 1 and 100 mg/kg of NAC administered IP for 21 days), and Group F (100 mg/kg of NAC administered IP for 21 days and a single 10 mg/kg dose of DOX administered IP 24 h before sacrifice). The ovaries were examined using B-mode US on days 1, 14, and 21, and the histopathological examinations of the ovaries and the uterus were undertaken after sacrifice on day 22. Results Histomorphological analyses showed that ovarian weight decreased after DOX administration in Group B but not in Group E. US revealed a transient increase in ovarian size in Group B and E, reverting to baseline levels over time, as well as a progressive increase in peritoneal fluid in Groups B and E. Group B exhibited a significant decrease in the thickness of the endometrium and myometrium and uterine cornual length, which was not observed in Group E. Histopathological examination showed that DOX caused a decline in follicular count, especially in primordial, secondary, and Graafian follicles, and resulted in follicular atresia, predominantly in Group B. Destructive degeneration/necrosis and vascular changes were most prominently seen in the corpus luteum of Groups C and B. In NAC-treated rats (Groups E and F), although germ cell damage was present, atretic follicles and vascular changes, such as hyperemia and congestion, were reduced. The anti-m & uuml;llerian hormone (AMH) level was the highest in Group F. Conclusions NAC, an antioxidant, attenuated DOX-induced gonadotoxicity in rats.
Ultraviolet light accelerates the degradation of polyethylene plastics
(Wiley, 2021) Doğan, Mustafa
Polyethylene plastics are widely used in daily life in the packaging of foodstuffs, pharmaceuticals, cosmetics, detergents, and chemicals. In this study, low-density polyethylene (LDPE) was exposed to an ultraviolet (UV) fluorescence lamp in simulated aging and degradation experiments. Ultraviolet degradation mechanisms were investigated on the surface after sunlight and UV lamp exposure. The plastic surfaces' molecular and surface degradation results were compared with their Fourier Transform Infrared-Attenuated Total Reflectance (FTIR-ATR) and ultraviolet visible (UV-Vis) spectra. By growing the length of exposure time increased stages of degradation were observed. After UV lamp and sunlight exposure, changing degradation levels were also determined with spectroscopic evaluations and the results were compared. LDPE was selected since it has a simple structure and a number of branched polymer structures that facilitate easily disruption of the chemical bond. Breaks in the polymer chain were easily seen in the plastics at the end of degradation and a fragile structure was formed throughout the polymer chain after accelerating UV light aging. The FTIR spectrum clarified the changed and fractured molecular bond structures of UV-exposed polyethylene. The change in the molecular structure of the plastic caused small changes in its color and small variations in this color change were detected by recording the Ultraviolet-Visible (UV-Vis) spectrum. The Philips UV lamp's light intensity and the wavelength spectrum range were measured. The UV lamp and sun UV light doses were calculated and compared.
Role of active slip systems induced with holmium impurity in Bi-2212 ceramics on mechanical design performance and morphological properties
(Elsevier Sci Ltd, 2022) Ülgen, Asaf Tolga; Çetin, Samet; Zalaoglu, Y.; Turkoz, M. B.; Erdem, Ümit; Yıldırım, Gürcan
Effect of Ho/Bi partial replacement in Bi2.1-xHoxSr2.0Ca1.1Cu2.0Oy (Bi-2212) superconductors on the fundamental structural, morphological and mechanical performance properties are investigated by Scanning Electron Mi-croscopy (SEM) and Vickers hardness (Hv) measurement techniques. Crystallinity quality and surface morphology including the microcrystal coalescence orientations, grain alignment distributions, microscopic structural problems, microvoids, internal defects, uniform surface view, porosity and particle growth distribution are visually examined with the aid of SEM. Basic mechanical performance and characteristic features of Bi/Ho substituted Bi-2212 superconducting ceramics (0.00 <= x <= 0.10) are also determined with Vickers tests con-ducted at various loads intervals 0.245-2.940 N. Experimental findings show that the characteristic features enhance seriously in case of x = 0.01 due to refinement of crystallinity quality and slip systems. Thus, the op-timum Ho concentration presents the highest mechanical fracture strength to the load applied as a result of better uniform surface appearance and grain orientations, well-connected flaky layers, larger particle size distribution and denser structure, confirmed by the SEM investigations. Namely, much more load is required to accelerate the dislocation movement and crack propagation to the terminal velocity for critical size growth. The fracture predominantly takes place in the transcrystalline regions and hence the propagations are easily controlled with the optimum Ho dopant ions. On the other hand, the increase in the Ho ions in Bi-2212 structure induces the crack-initiating defects for new stress concentration sites. In conclusion, the permanent and non-recoverable deformations appear at even lower indentation test loads. All samples present indentation size effect feature depending on the dominant character of elastic recovery mechanism. Further, original hardness parameters are semi-empirically analyzed in the plateau limit regions using mechanical modelling approaches for the first time. Based on the analyses, Hays-Kendall model exhibits the closest results to the experimental findings.
Resorbable membrane design: In vitro characterization of silver doped-hydroxyapatite-reinforced XG/PEI semi-IPN composite
(Elsevier, 2023) Doğan, Deniz; Erdem, Ümit; Bozer, Büşra M.; Turkoz, Mustafa Burak; Yıldırım, Gürcan; Metin, Ayşegül Ülkü
In this study, the production and characterization of silver-doped hydroxyapatite (AgHA) reinforced Xanthan gum (XG) and Polyethyleneimine (PEI) reinforced semi-interpenetrating polymer network (IPN) biocomposite, known to be used as bone cover material for therapeutic purposes in bone tissue, were performed. XG/PEI IPN films containing 2AgHA nanoparticles were produced by simultaneous condensation and ionic gelation. Characteristics of 2AgHA-XG/PEI nanocomposite film were evaluated by structural, morphological (SEM, XRD, FT-IR, TGA, TM, and Raman) and biological activity analysis (degradation, MTT, genotoxicity, and antimicrobial activity) techniques. In the physicochemical characterization, it was determined that 2AgHA nanoparticles were homogeneously dispersed in the XG/PEI-IPN membrane at high concentration and the thermal and mechanical stability of the formed film were high. The nanocomposites showed high antibacterial activity against Acinetobacter Baumannii (A.Baumannii), Staphylococcus aureus (S.aureus), and Streptococcus mutans (S.mutans). L929 exhibited good biocompatibility for fibroblast cells and was determined to support the formation of MCC cells. It was shown that a resorbable 2AgHA-XG/PEI composite material was obtained with a high degradation rate and 64% loss of mass at the end of the 7th day. Physico-chemically developed biocompatible and biodegradable XG-2AgHA/PEI nanocomposite semi-IPN films possessed an important potential for the treatment of defects in bone tissue as an easily applicable bone cover. Besides, it was noted that 2AgHA-XG/PEI biocomposite could increase cell viability, especially in dental-bone treatments for coating, filling, and occlusion.
Removal of anionic dyes with glycidyl methacrylate-grafted polyethylene terephthalate (PET) fibers modified with ethylenediamine
(Springer, 2021) Bozkaya, Ogün; Günay, Kübra; Arslan, Metin; Gün Gök, Zehra
In this work, the epoxy groups of poly (ethylene terephthalate) PET copolymers grafted with glycidyl methacrylate (GMA) were modified with ethylenediamine (EDA) to form exclusive adsorbent for removal of congo red (CR) and acid violet7 (AV-7) in the aqueous environment. The graft copolymers (GMA-g-PET) were synthesized with different grafting yield by a radical polymerization process with using benzoyl peroxide (Bz(2)O(2)) as radical initiator. Amination of GMA-g-PET fibers using EDA was studied in different solvents, and maximum yield (w/w %) was obtained in the toluene. The grafted and modified fibers were analyzed by CHNS organic elemental analyzer, scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance spectroscopy (C-13-NMR). By SEM analysis, the morphological changes have been shown after grafting. The chemical changes after grafting and addition of EDA to the fibers have been proven with FTIR, NMR and elemental analysis. The thermal properties of the grafted and aminated fibers were researched with thermogravimetric analysis and differential scanning calorimeter analysis. The removal of dyes by the EDA-GMA-g-PET fibers was investigated in aqueous medium at different conditions. Optimum conditions of different parameters such as pH of medium, graft yield of GMA on the fibers, adsorption duration, initial concentration of dye molecules and effect of graft yield on amination reaction were examined. The optimum pH of CR and AV-7 removal was found 5 and 3, respectively. The removal yield was found about 100% for both dyes while initial concentration of dyes was changed from 10 to 400 mg/L. Adsorbed dyes with the fibers were desorbed with 1 M NaOH at room conditions.
Production and characterization of hybrid nanofiber wound dressing containing Centella asiatica coated silver nanoparticles by mutual electrospinning method
(Pergamon-Elsevier Science Ltd, 2022) Bozkaya, Ogün; Arat, Esra; Gök, Zehra Gün; Yiğitoğlu, Mustafa; Vargel, İbrahim
The aim of this work is to produce a therapeutic and antimicrobial nanofiber wound dressing material with suitable air permeability, water vapor transmission, water absorption, porosity, thermal and mechanical strength. For this purpose, first of all, Centella asiatica (CA) coated silver nanoparticles (CA-AgNPs) are synthesized with using CA extract as reducing and stabilizing agent. The green synthesized CA-AgNPs are characterized by UV-Vis spectroscopy, transmission electron microscope (TEM), zeta potential and fourier transform infrared (FTIR) spectroscopy measurements. The obtained CA-AgNPs give a single peak in the 420-430 nm range between 200 and 700 nm due to surface plasmon resonance (SPR). The average zeta potential and size of CA-AgNPs is found to be-30.4 mV and 14.8 +/- 7.3 nm, respectively. Then, poly caprolactone (PCL) and polyethylene oxide (PEO) nanofibers composition containing CA-AgNPs is synthesized by mutual electrospinning method. Before electrospinning, the PCL solution (12% w/v in chloroform/methanol (70%/30%, v/v)), PEO solution (3.5%, w/v in water) and PEO solutions containing 1%, 5% and 10% (v:v) of CA-AgNPs are prepared. In electrospinning experiments, to synthesis the PCL/PEO nanofibers containing CA-AgNPs, an electrospinning set-up consisting of two high voltage sources, an aluminum rotary roller collector and two syringe pumps (one with a double syringe and the other with a single syringe) is used. To produce the wound dressing materials, PEO solutions containing CA-AgNPs are placed on the double syringe pump and PCL solution is placed on the single syringe pump. The surface and physico-chemical properties of the produced hybrid nanofibers are characterized by field emission scanning electron microscopy (FESEM), energy dispersion spectrometry (EDS), FTIR, X-ray diffractometer (XRD), Brunauer-Emmett-Teller (BET) surface area and porosity analyzer. Also, the thermal and mechanical properties of the obtained materials are investigated. In addition, the air permeability, water uptake capacity, water contact angle, water vapor transmission, in vitro degradation and silver release behavior of the samples are investigated. The results show that mutual dual-spinneret electrospinning technique combines the features of dissimilar components without corruption. Moreover, the in vitro degradation profile and silver release results show that these nanofibers could be used in wound dressing applications in the long term. With antimicrobial studies, PEO/ PCL nanofibers containing 5% and 10% CA-AgNPs are found to be effective against Staphylococcus aureus, Escherichia coli and Candida albicans. Also, the cytotoxic properties of nanofibers are investigated by MTT (3-[4,5dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay and results show the good biocompatibility for L929 fibroblast cells. Results reveal that CA-AgNPs loaded PCL/PEO hybrid nanofibers materials synthesized in this study has a promising potential for wound healing applications.
Polymer-layered oxygen sensor design and testing
(Springer, 2021) Doğan, Mustafa
Sensors have a wide range of applications from industrial production stages to medical respiratory equipment. The oxygen sensor is also one of the essential sensors to follow up the environmental oxygen level for humans. As an example, a 21% oxygen level is necessary to live safely in an environment and this would create a vital risk for a human being after lowering below 16% oxygen levels. Also in OLED production and lithium battery production processes, following and stabilizing the oxygen level below 5 ppm is mandatory in a glove box while production stages go on. Zirconium oxide is a known metal oxide that gives a sensory response to lowered oxygen levels. In this study, all sensor devices were produced over FTO(fluorine-doped tin oxide) glasses. Sol-gel-derived zirconium(IV) oxide chloride was used as an oxygen detection layer. Zirconium(IV) oxide chloride-coated FTO glass sensor worked successfully and gave a small increasing signal response to changing oxygen levels. A well-known commercially produced PEDOT-PSS(Poly(3,4-ethylene dioxythiophene) polystyrene sulfonate) polymer hole transfer layer was used to increase the oxygen gas sensor's sensitivity and detection range. This second device's performance was evaluated; this added layer could not improve the sensor performance. A new third device was designed; as a new layer over the zirconium-sensing layer, a third LiF layer was added. The third device was tested; polymer, zirconium, and LiF layered the third device and it worked efficiently in a lower oxygen level; furthermore, this design also improved the oxygen sensor detection range.
Physico-chemical characterization of food grade natural spring salt from the Central Anatolia region of Turkey and investigation of its microplastic content
(Springer India, 2024) Bozkaya, Ogün; Aluç, Yaşar
Delice salt is a natural spring salt obtained from the evaporation of spring water from the Central Anatolia region of Turkey and is a food grade salt with a geographical indication certificate. The aim of this study was to evaluate the compliance of Delice natural spring salt (Delice NSS), a commercial product, with food grade criteria by physicochemical characterizations and to investigate whether it contains microplastics. The NaCl%, moisture suspended solids and acid insoluble matter contents of Delice NSS were analyzed and determined as 98.79% (w/w), 0.301% (w/w), 0.16% (w/w) and 0.01% (w/w), respectively. Sodium, other minerals, and heavy metals were analyzed by inductively coupled plasma-optical emission (ICP-OES) spectrometry. In addition, fluoride, nitrate, and sulphate ions were analyzed by ion chromatography (IC). The chemical and thermal properties of Delice NSS were characterized by FTIR, X-ray fluorescence (XRF) and thermogravimetric analyzer (TGA). Moreover, Delice NSS was investigated whether it contains microplastics and some particles were detected under fluorescence microscopy. However, it was concluded that particles were not microplastics after TGA and FTIR analyses. The results revealed that Delice NSS does not carry a risk in terms of physicochemical properties as a foodstuff.
Phosphorus-nitrogen compounds: part 68. Synthesis, characterization, stereogenism, photophysical and bioactivity studies of novel unsymmetrical dispiro(N/N)cyclotriphosphazenes with carbazolyl and 4-chlorobenzyl pendant arms
(Royal Soc Chemistry, 2023) Cemaloğlu, Reşit; Asmafiliz, Nuran; Kilic, Zeynel; Cosut, Bunyemin; Sabah, Busra Nur; Acik, Leyla; Cerci, Nebahat Aytuna
Organic-inorganic hybrid multi-heterocyclic unsymmetrical cis/trans dispirocyclotriphosphazenes with different pendant arms were obtained and their spectral, stereogenic, photophysical and bioactivity properties were investigated. To prepare these phosphazenes, the starting compounds tetrachloro(4-chlorobenzyl)spiro(N/N)cyclotriphosphazenes, (ClBzSpiro-5)R-1(N3P3)Cl-4 [Bz: Benzyl; R-1: Me (1) and R-1: Et (2)], were prepared regioselectively from the reactions of hexachlorocyclotriphosphazene, N3P3Cl6 (HCCP, trimer) with N-methyl/ethyl-N'-(4-chlorobenzyl)-1,2-diaminoethanes. Reactions of tetrachlorocyclotriphosphazenes (1 and 2) and 9-ethyl-N-methyl-3-carbazolyl-1,2-diaminoethane (3) or 9-ethyl-N-methyl-3-carbazolyl-1,3-diaminopropane (4) produce new cis/trans-dispirocyclotriphosphazenes, [(ClBzSpiro-5)R-1(N3P3)(CzSpiro-n)R-2]Cl-2 (Cz: Carbazolyl; R-1, R-2: Me or Et; n = 5 or 6; (5a-8a and 5b-8b), containing unsymmetrical spiro-architectures. In addition, the structures of trans-7a and cis-7b isomers were clarified by single crystal X-ray crystallography. The chiralities of trans-7a and cis-7b were confirmed using X-ray crystal structures, P-31 NMR spectra recorded upon the addition of chiral solvating agent [(S)-(+)-2,2,2-trifluoro-1-(9 & PRIME;-anthryl)ethanol; CSA], and circular dichroism (CD) spectra. Moreover, the photophysical properties of phosphazenes showed a fluorescence profile with lifetimes of about 4.9-6.6 ns and quantum yields in the range of 0.10-0.14. Additionally, the antibacterial and antifungal activities of the newly synthesized phosphazenes against some bacteria and yeast strains and their interactions with pBR322 plasmid DNA were investigated. The bacterial strain most susceptible (MIC = 156.3 mu M) to compounds 5a and 8a was P. aeruginosa. However, it was found that the yeast strain most susceptible (MIC = 156.3 mu M) to compounds 5b, 7a, 7b and 8b was C.albicans. The cytotoxic activities of 5a, 5b, 7b and 8a against L929 fibroblast and MCF-7 breast cancer cells were determined. However, cis-5b showed reasonable antioxidant activity with a radical scavenging value of 35.20%.
Novel Electrospun Cotton-Like Nano/Microfiber from Waste Polycarbonate Plastic for Use as Filler Fiber in Outerwear Textiles
(Korean Fiber Soc, 2023) Bozkaya, Ogün
Synthetic fibers, which have many different uses, have replaced natural filling materials as filling fibers in clothing textiles today. In the textile industry, the use of recycling plastics has gained importance due to the difficulties in raw material supply, energy saving and increasing environmental problems. Polycarbonate (PC) is an important engineering plastic with increasing waste due to its use in many industries in recent years. The aim of this study is to produce cotton-like (CL) material from waste PC (wPC) plastic by electrospinning method to be used as filling fiber in outerwear textiles. The synthesized CL-rPC material was characterized using field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) techniques. In addition to these, properties that determine textile comfort such as wettability, water vapor transmission rate (WVTR), water adsorption capacity (WAC) and thermal insulation were investigated. Morphological analysis showed that the mostly nano-sized fibers were smooth and bead-free. The mean fiber diameter was determined as 585 +/- 373 nm. The FTIR spectra of the wPC and CL-rPC nano/microfibers (CL-rPC NMFs) were compared and the similarity between them was found to be 98.39%. Water contact angle, WVTR and WAC of CL-rPC NMFs material were measured as 139.15 +/- 0.07 degrees, 6103.41 +/- 117.76 g/m(2)/day and 17.53 +/- 1.81%, respectively. Moreover, the thermal conductivity of CL-rPC NMFs material was determined as 0.0363 +/- 0.0094 W/mK. The results reveal that CL-rPC NMFs material produced from recycled PC can be a potential candidate for filling fiber applications that can provide thermal comfort conditions in outerwear textiles.
Investigation of the biocompatibility and in vivo wound healing effect of Cotinus coggygria extracts
(Ankara Univ, 2024) Bozkaya, Esra; Türk, Mustafa; Ekici, Hüsamettin; Karahan, Siyami
Cotinus coggygria is widely recognized its antiseptic, anti-inflammatory, antimicrobial, antihemorrhagic, and wound-healing properties. In this, aimed to evaluate the phenolic contents, cytotoxicity/proliferation, hemolytic, antimicrobial, genotoxic, apoptotic, necrotic activities, and in vivo wound healing effects of C. coggygria, , a plant species known to have beneficial effects on wound healing. TOF-LC/MS analyzes revealed that the methanol extract of C. coggygria leaves contained flavonoids and phenolic compounds such as gallic acid (18.5 mg/kg), catechin (4.6 mg/kg), protocatesic acid (0.6 mg/kg), vanillic acid (8.4 mg/kg), ellagic acid (0.1 mg/kg), rosmarinic acid (0.1 mg/kg), quercetin (15 ppb) and C. coggygria stems contained such as gallic acid (24.6 mg/kg), catechin (155.1 mg/kg), chlorogenic acid (1.9 mg/kg), 4hydroxybenzoic acid (383.3 mg/kg), rutin (2.5 mg/kg), ellagic acid (15.1 mg/kg), apigenin 7-glycoside (10.5 mg/kg), rosmarinic acid (0,4 mg/kg), quercetin (15.2 mg/kg), naringenin (279.1 mg/kg). Consequently, C. coggyria has a positive effect on wound healing with antibacterial properties, particularly against E. coli, and without cytotoxic, genotoxic, or hemolytic effects at test concentrations. In the in vivo burn model, wounds treated with leaf and stem extracts healed faster than the control group. Thus, C. coggygria is an effective plant for wound healing with antibacterial properties, particularly against E. coli, and without cytotoxic, genotoxic, and hemolytic effects.
Investigation of the in vitro antibacterial, cytotoxic and in vivo analgesic effects of silver nanoparticles coated with Centella asiatica plant extract
(Ankara Univ, 2023) Bozkaya, Ogun; Ekici, Hüsamettin; Gün Gök, Zehra; Arat, Esra; Ekici, Seda; Yigitoglu, Mustafa; Vargel, İbrahim
In recent years, researchers have shown an increased interest in using medicinal plants for the synthesis of silver nanoparticles (AgNPs) having various therapeutic properties. Centella asiatica (CA), a medicinal plant, has been used to treat minor burn wounds, psoriasis, and hypertrophic wounds among many other pathological conditions. The current study aimed to synthesize CA coated AgNPs (CA-AgNPs) with appropriate biocompatibility and various therapeutic properties, including antimicrobial and analgesic activities. The synthesized CA-AgNPs were characterized by ultraviolet-visible (UV-Vis) spectroscopy, zeta potential measurements, and fourier transform infrared (FT-IR) spectroscopy. The formation of spherical CA-AgNPs was confirmed by a single surface plasmon resonance (SPR) peak emerging at 420 nm wavelength by UV-Vis. The average hydrodynamic diameter and zeta potential of the particles were found to be 29.5 nm and -24.5 mV, respectively. The FT-IR analyses showed that the AgNPs were coated and stabilized by bioactive compounds from the CA extract. MTT cytotoxicity assay revealed that CA-AgNPs at <= 1 mM concentrations exhibited biocompatibility for L929 fibroblast cells. The antimicrobial activity of CA-AgNPs was confirmed by significant inhibition of Staphylococcus aureus and Escherichia coli. In addition, the analgesic effect of CA-AgNPs was investigated for the first time in the literature by tail-flick and hot plate methods, and statistically significant results were obtained for both methods. Taken together, these results suggest that CA-AgNPs can be used as an effective antibacterial and analgesic agent in a variety of biomedical applications, including coating wound dressings.
Evaluation of melamine and cyanuric acid cytotoxicity: an in vitro study on L929 fibroblasts and CHO cell line
(ANKARA UNIV PRESS, 2020) Melekoglu, Abdullah; Ekici, Husamettin; Arat, Esra; Karahan, Siyami
Melamine and its metabolites pose health concern as they are used in various industrial products including feed and drugs. There are a limited number of studies on melamine and cyanuric acid cytotoxicity and cellular damage without a certain conclusion. The present study aimed to evaluate melamine, cyanuric acid and its combined cytotoxic effects using 3-(4.5-dimethylthiazol-2-yl) methyl thiazole tetrazolium (MTT) bromide test. The study also evaluated apoptotic and necrotic effect using a double staining method of Hoechst 33342 and propidium iodide. Melamine, cyanuric acid and their combination (1:1) were applied to L929 fibroblasts and Chinese hamster ovary (CHO) cells at various concentrations (1000 mu g/mL, 500 mu g/mL, 250 mu g/mL, 125 mu g/mL and 62.5 mu g/mL). At the highest concentration (1000 mu g/mL), the cell viability dropped down approximately to 50% both in CHO cells and L929 cells. Melamine, cyanuric acid and their mixture caused cytotoxicity in CHO cells and L929 fibroblasts in dose-dependent manner Cell death occurred through both apoptosis and mainly necrosis. Both cell types were more sensitive to the mixture of melamine and cyanuric acid and, furthermore, CHO cells were more sensitive than L929 fibroblasts. As a result, melamine, cyanuric acid and their combination caused cytotoxicity in CHO cells and L929 fibroblasts. Further studies should be conducted in different cell lines. These studies should also aim to reveal the mechanism of cytotoxicity and related pathways.
Production of 2-hydroxyethyl methacrylate-g-poly(ethylene terephthalate) nanofibers by electrospinning and evaluation of the properties of the obtained nanofibers
(WILEY, 2020) Gok, Zehra Gun; Inal, Murat; Bozkaya, Ogun; Yigitoglu, Mustafa; Vargel, Ibrahim
Nanofiber production was investigated from poly(ethylene terephthalate) (PET) polymers functionalized with hydroxyethyl methacrylate (HEMA) by grafting of HEMA monomers onto the PET fibers. HEMA grafted PET (PET-g-HEMA) copolymers were analyzed by scanning electron microscopy, Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy. PET and PET-g-HEMA were dissolved in trifluoroacetic acid and nanofibers were obtained by electrospinning. It was found that the PET and PET-g-HEMA polymers having grafting yield 20 and 55% could be converted to continuous, smooth, and beadles nanofibers. For characterization of the nanofiber membranes, thermogravimetric analysis, differential scanning calorimeter analysis, surface contact angle measurement, porosity analysis, and mechanical tests were applied. When compared with the original PET nanofibers, the thermal properties and degradation process of PET-g-HEMA nanofibers changed according to the amount of HEMA present in the structure of nanofibers. The contact angles of the nanofibers obtained from PET-g-HEMA polymers decreased whereas the water retention ability of the nanofibers increased compared to original PET nanofibers. The porosity of PET-g-HEMA nanofibers was found be high compared to PET nanofibers and whereas the mechanical properties of PET was higher than PET-g-HEMA nanofibers. The obtained nanofibers can be used in many fields such as biomaterial applications.
Preparation of a novel functionalized magnetic nanobiocomposite as a carrier for protein adsorption
(TAYLOR & FRANCIS INC, 2020) Metin, Aysegul Ulku; Dogan, Mustafa; Erdem, Umit; Babacan, Taner; Gungunes, Hakan
This study aims the synthesis of a novel functionalized magnetic nanocarrier based on xanthan gum biopolymer. Glycidyl methacrylate was grafted on xanthan gum chains by radical polymerization reaction using two types of initiators: ammonium persulfate and benzoyl peroxide. Characterization studies of the magnetic nanocarrier were performed using several instruments such as Fourier Transform Infrared Spectroscopy, Scanning Electron Microscopy, Energy-Dispersive-X-Ray Spectroscopy, X-Ray Diffraction Spectroscopy, Transmission Electron Microscopy, Mossbauer Spectroscopy, and Vibrating Sample Magnetometer. According to the Vibrating Sample Magnetometer data and Mossbauer analysis, Fe atoms were incorporated successfully in the polymer chains in Fe3+ state and magnetic nanocarrier has super-paramagnetic behavior, respectively. Epoxy groups on magnetic nanoparticles were converted to carboxylic acid groups using iminodiacetic acid and then tested to usability as a carrier for immobilization of proteins such as albumin, lipase and cytochrome c. The adsorption of albumin and lipase on magnetic nanoparticles were pH-dependent while cytochrome c was immobilized in a wide range of pH value. The calculated maximum experimental immobilization capacity of magnetic nanoparticles was 65.10 mg g(-1), 62.0 mg g(-1) and 188.0 mg g(-1) for albumin, lipase and cytochrome c, respectively. Experimental data fitted to Langmuir isotherm better than Freundlich. The rate of cytochrome c adsorption followed the pseudo-second-order kinetic. Results showed that the functionalized magnetic nanoparticles can be effectively used as a carrier for protein separations, especially for cytochrome c. Moreover, the functionalized magnetic nanocarrier had high affinity to Cytochrome c protein even in multiple protein systems.
Investigation on phenol degradation capability of Scenedesmus regularis: influence of process parameters
(TAYLOR & FRANCIS LTD, 2020) Basaran Kankilic, Gokben; Metin, Aysegul Ulku; Aluc, Yasar
Phenol removal from environmental solutions has attracted much attention due to phenol's high toxicity, even at low concentrations. This study aims to reveal the phenol biodegradation capacity of Scenedesmus regularis. Batch system parameters (pH, amount of algal cell, phenol concentration) on biodegradation were examined. After 24 h of treatment, 92.16, 94.50, 96.20, 80.53, 65.32, 52 and 40% of phenol were removed by Scenedesmus regularis in aqueous solutions containing 5, 10, 15, 20, 30, 40 and 50 mg/L of phenol, respectively. To describe the correlation between degradation rate and phenol concentration, the Michaelis-Menten kinetic equation was used where V-max and K-m are 0.82 mg phenol g algea(-1) h(-1) and 24.97 ppm, respectively. Phenol remediation ability of S.regularis can enable the usage of the spent biomass as biofuel feedstock and animal feed makes it a 'green' environmental sustainable process.
Effect of vanadium addition on fundamental electrical quantities of Bi-2223 crystal structure and semi-empirical model on structural disorders-defects
(SPRINGER, 2020) Ulgen, A. T.; Erdem, U.; Zalaoglu, Y.; Turgay, T.; Yildirim, G.
The primary contribution of the present study is to determine the effect of vanadium addition on the fundamental aspects of characteristic crystalline and electrical quantities for the Bi1.8Sr2.0Ca2.2Cu3.0VxOy (0.00 <= x <= 0.30) crystal system using the powder X-ray diffraction (XRD), temperature-dependent electrical resistivities and semi-empirical approaches founded on the structural disorders-defects. The de electrical resistivity results show that every electrical quantity is found to degrade regularly with the increment in the addition level as a consequence of the induced permanent structural disorders-defects, intergranular grain boundary coupling interaction problems and non-superconducting barrier regions in the bulk Bi-2223 superconducting system. The vanadium addition brings also about the characteristic transition from over-doped state to under-doped state due to the suppression in the overlapping of Cu-3d and O-2p wave functions. The XRD results indicate that the vanadium addition leads to shift the characteristic peaks towards the larger/lower angles in terms of the peak positions in the reference data, enlarge the diffraction peak widths (line broadening of X-ray diffraction), appear or disappear new peaks, increase/decrease the average grain size, lattice cell parameters and superconducting phase fractions founded on the diffraction intensities. Based on the evidences, the presence of vanadium particles in the bulk Bi-2223 superconducting phase damages crucially the fundamental characteristic features. Moreover, it is found that characteristic two-stage (bulk genuine, T-c(mid) and coherence, T-co) transition temperatures decrease systematically with the addition level. On this basis, the presence of vanadium impurity in the system leads to degrade the stabilization of superconductivity in the small homogeneous clusters in the paths and especially effective electron-phonon coupling (bipolaron in the polarizable lattices) probabilities due to the reduction of hole trap energy per Cu ions in the valence band of system. Additionally, the results display that the vanadium particles affect negatively on both the dirty limit characteristic feature and gap coefficient of Bi-2223 ceramic compound as a result of the decrement in the minimum required energy for breaking up the cooper-pairs in the system. At the same time, the electrical resistivity curves enable us to develop a sensitive semi-empirical approach to find the possible highest onset critical transition temperature for the ideal crystallinity. The model founded on the crystallinity quality displays that the possible highest onset transition temperature is about 116.037 K +/- 1.25587 K with R-adj(2) = 0.948.
Determining the lowest sulfur detection limit in diesel fuel by ultraviolet fluorescence
(TAYLOR & FRANCIS LTD, 2020) Dogan, Mustafa
This technical review article focuses on determining a robust and precise lower-level sulfur detection procedure. When measuring under 0.1 ppm and approaching zero values, the limits of the instrument are pushed to separate real signal response from noise. One of the performance parameters in method validation studies is to determine these near-zero value samples reliably when the instrument works near the noise signal level. The study examined the early stages of the method development process, regarding the determination of the validation parameters limit of blank, limit of detection (LOD), and limit of quantification (LOQ). The sulfur content in diesel fuel was determined with guidance from the standard ISO 20846:2011. The average sulfur readings of a diesel test sample and blank (99% iso-octane) were measured as 3.9 and 0.0196 ppm, respectively. For a 1.5% diluted diesel test sample the mean sulfur value was measured as 0.0613 ppm and this value was verified as the LOD. For a 3% diluted diesel test sample the mean sulfur value was measured as 0.1158 ppm and this result was verified as the LOQ. The LOD and LOQ were tested for conformity. The accuracy of these tested values was checked according to EUROCHEM guidelines.
A novel research on the subject of the load-independent microhardness performances of Sr/Ti partial displacement in Bi-2212 ceramics
(SPRINGER, 2020) Zalaoglu, Y.; Turgay, T.; Ulgen, A. T.; Erdem, U.; Turkoz, M. B.; Yildirim, G.
This work is interested in the critical changes in the load-independent microhardness performance parameters with the partial substitution of Sr2+ inclusions for the Ti4+ impurities in the Bi-2212 inorganic solids with the help of the theoretical approximations as regards Meyer's law (ML), proportional sample resistance (PSR), modified proportional sample resistance (MPSR), elastic/plastic deformation (EPD), Hays-Kendall (HK) and indentation-induced cracking (IIC) models found on the experimental microhardness tests applied to a variety of test loads between 0.245 and 2.940 N for the first time. Moreover, Ti-substituted Bi-2212 bulk ceramics (Bi2.1Sr2.0-xTixCa1.1Cu2.0Oy) are prepared within mole-to-mole ratios of x = 0.000, 0.010, 0.030, 0.050, 0.070, 0.100 by the standard solid-state reaction method in the atmospheric pressure conditions. It is provided that Ti partial substitution in the superconducting system descends unsmilingly the mechanical durability, stability, strength, toughness, critical stress, stiffness and flexural strengths of Bi-2212 superconducting solids studied owing to the increment of crystal structural problems. Moreover, it is obtained that the degradation in the crystal structural leads to diminish the typical ISE characteristic of Bi-2212 superconducting ceramic compounds. At the same time, the results show that all the models (especially IIC approach) can serve as the suitable descriptors for the determination of the variation in the load-independent mechanical performances of the Bi-2212 superconducting materials.

Güncel Gönderiler