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Öğe Beyond Conventional: Antibacterial, Antioxidant, and Photocatalytic Properties of Nanofibers Featuring Metal-Oxide-Modified Boron Nitride Nanoparticles(Amer Chemical Soc, 2024) Horzum, Nesrin; Dogan, Deniz; Karaduman, Fatma Rabia; Metin, Aysegul UlkuCuO-, ZrO2-, and ZnO-immobilized functional boron nitride (fBN) nanoparticles were synthesized by an environmentally friendly approach using a Stevia rebaudiana extract. Metal-oxide-immobilized fBN nanoparticles (fBN/MO)-incorporated (1 wt %) polyvinyl alcohol/poly(acrylic acid) composite nanofibers were fabricated by electrospinning, and their antibacterial, antioxidant, and photocatalytic properties were investigated. fBN/CuO and fBN/ZnO nanoparticles were distributed randomly, showcasing nonuniform geometries besides polygonal-shaped fBN/ZrO2 nanoparticles. fBN/MO nanoparticles exhibited a uniform dispersion along the composite nanofibers, with diameters between 115 and 160 nm. The incorporation of fBN/MO nanoparticles into the composite nanofibers (0.074-0.753 W/mK) resulted in an improvement in both thermal stability and conductivity when compared with PVA/PAA nanofibers (0.063 W/mK). fBN/MO-modified composite nanofibers exhibited an antibacterial efficacy exceeding 99% against Streptococcus mutans, Acinetobacter baumannii, Escherichia coli, and Staphylococcus aureus, augmenting their antioxidant properties. The modified composite nanofibers, particularly those incorporating fBN/ZrO2 nanoparticles, exhibited effective photocatalytic remediation against methylene blue (MB) with the highest activity, attributed to their favorable morphological and optoelectronic properties, resulting in a remarkably more than 20-fold improvement. Enhanced stability for repeated treatment of MB for a minimum of three cycles was achieved. The multifunctional nature of nanofibers unveils synergistic antibacterial, antioxidant, and photodegradation effects, positioning them as promising for biomaterials and water disinfection.Öğe Bioremoval of mercury (II) from aqueous solutions by Phragmites australis: Kinetic and equilibrium studies(Taylor & Francis Inc, 2018) Kankilic, Gokben Basaran; Metin, Aysegul Ulku; Aluc, Yasar; Bozkaya, OgunIn this study, the removal of mercury (II) ions from aqueous solutions by dried biomass of Phragmites australis was investigated in the batch system. The biomass was characterized by Fourier transform infrared spectroscopy (FT-IR), energy dispersive X-ray fluorescence (ED-XRF), Brunauer-Emmett-Teller (BET) surface area techniques (BET). Inductively Coupled Plasma Atomic Emission Spectrophotometer (ICP-OES, Spectro Blue) was used to analyze Hg(II) concentration and obtained data in batch experiments indicated that Hg (II) was rapidly adsorbed and such adsorption reached equilibrium within 60 min. The initial pH of the solution was effective parameter for Hg (II) biosorption. The biosorption kinetics was in better good fit with pseudo-second order kinetics and the results obtained from the batch experiments were conformed better with the Langmuir isotherm model than Freundlich and D-R isotherm models. The maximum Hg (II) biosorption capacity of P. australis was 20.0 +/- 0.4mg/g. The availability of other metal ions affected mercury biosorption. Adsorption/desorption studies demonstrated that the adsorbed Hg (II) could be desorbed effectively with a 0.1M ethylenediamine tetra-acetic acid (EDTA) solution. The biosorption capacity of the regenerated biosorbent could still be maintained at 72% at the fifth adsorption-desorption cycle. Consequently, it can be said that P. australis can be used as an applicable, cost-efficient, nature friendly biosorbent for treating wastewater. [GRAPHICS] .Öğe Chitosan based metal-chelated copolymer nanoparticles: Laccase immobilization and phenol degradation studies(Elsevier Sci Ltd, 2017) Alver, Erol; Metin, Aysegul UlkuImmobilization improves the stability and reusability of enzymes. In this study, laccase, which is a green biocatalyst, was immobilized onto Cu (II)-chelated chitosan nanoparticles via adsorption and successfully applied to remove phenol from aqueous solution. Cu (II)-chelated chitosan-graft-poly (glycidyl methacrylate) nanoparticles were prepared using poly (ethylene imine), PEI, which is employed as both a spacer arm and metal chelator and used to immobilize laccase by coordination. Properties of chitosan based nanoparticles were characterized using FTIR, TGA, SEM and zeta-sizer analysis. The maximum laccase loading capacity of Cu (II)-chelated chitosan based nanoparticles (CHT-PGMA-PEI-Cu (II) NPs) was calculated as 65.75 +/- 2.51 mg/g. This immobilized system exhibited broad pH and temperature profiles, and better stability and reusability than free enzyme; after eight cycles of continuous use, the activity of the immobilized enzyme remained above 50 +/- 0.62%. The K-m and V-max values of free and immobilized laccase were 0.055 mM, 0.070 mM, and 0.19 U/mg, 0.14 U/mg, respectively. The catalytic efficiencies (V-max/K-M) of the free and immobilized laccase were 3.45 and 2.0, respectively. Feasibility of the laccase immobilized system in the removal of phenol was investigated in a batch system. The results showed that the CHT-PGMA-PEI-Cu (II) NPs have great potential for industrial applications. More than 96% of phenol was removed with laccase immobilized metal chelated NPs in the presence of mediator, ABTS, indicating that the metal-chelated chitosan based NPs is a promising support for both laccase immobilization and further applications in the removal of phenolic compounds. (C) 2017 Elsevier Ltd. All rights reserved.Öğe Colorimetric Bisphenol-A Detection With a Portable Smartphone-Based Spectrometer(Ieee-Inst Electrical Electronics Engineers Inc, 2018) Bayram, Abdullah; Horzum, Nesrin; Metin, Aysegul Ulku; Kilic, Volkan; Solmaz, Mehmet ErtugrulWater quality monitoring in resource-limited settings without access to a sophisticated laboratory requires the development of low cost and portable instrumentation. Herein, we propose a newly designed handheld reflection-based smart-phone sensing platform to detect Bisphenol-A (BPA), a well-known endocrine disruptor agent abundantly used in plastic industry. An experimental investigation relying on color change due to the formation of quinone-type complex was conducted with samples from two different water sources: distilled and commercial drinking water. This colorimetric measurement device was used to determine BPA in distilled water in alkaline environments. The successful combination of colorimetric assay and spectrometer facilitates limit of detection in the low ppm levels, 0.29 ppm for smartphone and 0.23 ppm for commercial spectrometer, with a sensitivity of 0.1/ppm.Öğe Environmentally friendly pathway applying sustainable resources to remove anionic dye from aqueous solutions: encapsulation in carboxymethyl cellulose nanoneedles(Springer Int Publ Ag, 2023) Alver, Erol; Dogan, Deniz; Mert, Humeyra; Metin, Aysegul UlkuEncapsulation technique was used for the rapid and efficient removal of RB-250 from aqueous solutions. This technique involves the simultaneous formation of carboxymethyl cellulose (CMC) particles and the entrapment of the anionic dye RB-250 within the particles. TEM and zeta analyses of dye-encapsulated CMC particles showed needle type agglomeration of nanoparticles. Various parameters were investigated to optimize the RB-250 removal efficiency of CMC by encapsulation. Remarkably, while pH and time significantly affect the dye removal efficiency in adsorption, which is a widely used dye removal technique, the effect of these parameters is negligible in the proposed technique. In addition, it was determined that the temperature and stirring rate does not have a significant effect on the entrapment of the dye molecules in nanoparticles. More importantly, unlike conventional dye removal techniques such as adsorption, this technique allowed the rapid and efficient removal of an anionic dye with unmodified CMC. RB-250 encapsulation capacity of CMC nanoparticles was determined as 2809 mg RB-250/g CMC. These results revealed that the encapsulation is a promising candidate in dye removal applications where time and ease are important.Öğe Evolution of dynamics of physico-chemical and mechanical properties of hydroxyapatite with fluorine addition and degradation stability of new matrices(Elsevier, 2022) Erdem, Umit; Dogan, Deniz; Bozer, Buesra Moran; Karaboga, Seda; Turkoz, Mustafa Burak; Metin, Aysegul Ulku; Yildirim, GurcanThis multidisciplinary study examined sensitively the change in the dynamics of main mechanical performance, stability of crystal structure, crystallinity quality, strength, corrosion resistance, biocompatibility, resistance to structural degradation/separations and mechanical durability features of hydroxyapatite (HAp) biomedical materials based on the fluorine addition and degradation process to guide future medical and dental treatment studies. In the study, the fluorine ions were used to be the dental coating, filling and supporting material for biologically or synthetically produced bone minerals. The general characteristic properties were investigated by means of standard spectroscopic, structural and mechanical analysis methods including RAMAN, SEM-EDS, TEM, Vickers micro-indentation hardness and density measurements. A time dependent release test was performed to evaluate possible fluorine ion release after the degradation process. It was found that the fundamental charac-teristic properties of HAp biomedical materials are noted to improve with the increase in the fluoride level up to 2% due much more stabilization of HAp crystal system. The combination of RAMAN spectra and powder XRD analyzes indicates that 2% addition level affects positively the formation velocity of characteristic HAP phase. Besides, fluorine doped HAp materials all exhibited the main characteristic peaks after degradation process. This is attributed to the fact that the fluorine ions enabled the hydroxyapatite to enhance the structural quality and stability towards the corrosion environment. However, in case of excess dopant level of 3% the degradation rates were obtained to increase due to higher contribution rate and especially electrostatic interactions. As for the surface morphology examinations, 2% fluorine added HAp with the highest density of 3.0879 g/cm3 was determined to present the superior crystallinity quality (smallest grain size, best smooth surface, honeycomb pattern, regular shaped particles and densest particle distributions through the specimen surface). Conversely, the excess fluorine triggered to increase seriously degree of micro/macro porosity in the surface morphology and microscopic structural problems in the crystal system. Thus, the HAp doped with 3% was the most affected material from the degradation process. Additionally, the fluorine ion values read after the release process were quite far from the value that could cause toxic effects. Lastly, the optimum fluorine addition provides the positive effects on the highest durability, stiffness and mechanical fracture strength properties as a consequence of dif-ferentiation in the surface residual compressive stress regions (lattice strain fields), amplification sites and active operable slip systems in the matrix. Hence, the crack propagations prefer to proceed in the transcrystalline re-gions rather than the intergranular parts. Similarly, it was found that Vickers micro-indentation hardness tests showed that the microhardness parameters increased after the degradation process. All in all, the fluorine addition level of 2% was noted to be good choice to improve the fundamental characteristic properties of hy-droxyapatite biomedical materials for heavy-duty musculoskeletal, orthopedic implant, biological and thera-peutic applications in medicine and dentistry application fields.Öğe Fibrous polymer-grafted chitosan/clay composite beads as a carrier for immobilization of papain and its usability for mercury elimination(Springer, 2016) Metin, Aysegul Ulku; Alver, ErolPapain, which is an industrially important enzyme, has been immobilized on fibrous polymer-modified composite beads, namely poly(methacrylic acid)-grafted chitosan/clay. Characterization studies have been done using FTIR and SEM analysis. Operating parameters such as pH and initial concentration of papain have been varied to obtain the finest papain immobilized polymermodified composite beads. The immobilization capacity of composite beads has been determined as 34.47 +/- 1.18 (n = 3) mg/g. The proteolytic activity of immobilized papain was operated using bovine serum albumin (BSA) and maximum velocity (V-max) and Michaelis-Menten constant (K-m) values of the free and immobilized enzymes were determined using Lineweaver-Burk and Eadie-Hofstee equations. Usability of papain immobilized polymermodified composite beads as adsorbents for the elimination of mercury was investigated. The maximum removal capacity of PIPMC beads has been found to be 4.88 +/- 0.21 mg Hg/g when the initial metal concentration and weight of polymer-modified composite beads were 50 mg/L and 0.04 g at pH 7, respectively. Mercury removal performance of the papain immobilized polymer-modified composite beads was investigated in conjunction with Cu (II), Zn (II) and Cd (II) ions. The mercury adsorption capacity of papain immobilized polymer-modified composite beads was a slight reduction from 1.15 to 0.89 mg/g in presence of multiple metal salts.Öğe Investigation on phenol degradation capability of Scenedesmus regularis: influence of process parameters(TAYLOR & FRANCIS LTD, 2020) Basaran Kankilic, Gokben; Metin, Aysegul Ulku; Aluc, YasarPhenol 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.Öğe INVESTIGATION THE PERFORMANCE OF CHITOSAN BASED COMPOSITE BEADS ON REMOVAL OF ANIONIC DYE (AY-204)(Yildiz Technical Univ, 2015) Alver, Erol; Metin, Aysegul Ulku; Ciftci, HakanThe aim of this study is to investigate the utility of chitosan/zeolite composite beads as adsorbent for removal of anionic textile dye, Acid Yellow 204. It was investigated the influence of parameters such as pH, time, zeolite content in the composite structure, electrolyte concentration, dye concentration and sorbent dosage on the efficiency of dye removal. It was determined that the adsorption capacity increased significantly with decreasing pH Langmuir and Freundlich isotherm models were applied to the experimental data to determine the adsorption mechanism. and The Langmuir isotherm model was determined to be more consistent with the experimental data. It was observed that the reaction kinetics is suitable for the pseudo-second-order.Öğe Magnetically responsive chitosan-based nanoparticles for remediation of anionic dyes: Adsorption and magnetically triggered desorption(Elsevier Science Sa, 2022) Babacan, Taner; Dogan, Deniz; Erdem, Umit; Metin, Aysegul UlkuChitosan-based nanoparticles (PGMA/mCHT) were prepared for the adsorption of anionic Reactive Red 120 (RR120) and Indigo Carmine (IC). The morphology and characteristics were clarified by using SEM-EDX, XRD, VSM, and FTIR. The adsorption of RR120 and IC on PGMA/mCHT was carried out in a batch process to determine the influence of initial dye concentration (5-600 mg/L), initial pH (3-9), temperature (5, 25, 35, and 45 degrees C) and contact time. Under acidic conditions, higher adsorption efficiencies of the PGMA/mCHT nanoparticles due to intermolecular interactions of dye molecules between the protonated amine groups and the sulfonyl groups. Bi-solute adsorption was also investigated revealing between dye molecules has no competitive effect at the same initial concentration. The kinetic results of RR120 and IC adsorption onto PGMA/mCHT nanoparticles fit well to the pseudo-second-order model. The desorption of dye molecules from PGMA/mCHT nanoparticles was also studied using an alternating magnetic field which is caused the superior desorption behavior demonstrating the magnetic nanoparticles can be acted as a nanoheater.Öğe Methylene blue adsorption on magnetic alginate/rice husk bio-composite(ELSEVIER, 2020) Alver, Erol; Metin, Aysegul Ulku; Brouers, FrancoisMagnetic alginate/rice husk (m-ALG/RH) bio-composite beads prepared with ionotropic gelation method and used for methylene blue (MB) removal. Structural analysis of magnetic alginate/rice husk composite beads was performed using FTIR, SEM-EDS and TGA techniques. The accomplishment of magnetic alginate/rice husk composite beads as an adsorbent for the removal methylene blue was investigated from aqueous solution. Maximum experimental adsorption capacity of the bio-composite beads was calculated as 274.9 mg/g. The various process parameters such as pH, temperature and initial MB concentration optimized. It was determined that pH no significant effect on dye removal efficiency of beads while temperature and ionic strength caused a decrease on removal efficiency. The various isotherm models were applied for determine the adsorption mechanism and Freundlich isotherm model is more compatible with the experimental data. The kinetic studies showed that the adsorption of methylene blue can be well described by the fractal Brouers-Sotolongo kinetic model. The thermodynamic calculations indicated that methylene blue adsorption was a spontaneous and exothermic nature. The results showed that the magnetic alginate/rice husk bio-composite as low-cost and eco-friendly adsorbent can be effectively used for cationic dye removal steps in the environmental engineering applications. (C) 2020 Elsevier B.V. All rights reserved.Öğe One step effective removal of Congo Red in chitosan nanoparticles by encapsulation(Pergamon-Elsevier Science Ltd, 2017) Alver, Erol; Bulut, Mehmet; Metin, Aysegul Ulku; Ciftci, HakanChitosan nanoparticles (CNPs) were prepared with ionotropic gelation between chitosan and tripolyphosphate for the removal of Congo Red. The production of chitosan nanoparticles and the dye removal process was carried out in one-step. The removal efficiency of Congo Red by encapsulation within chitosan from the aqueous solution and its storage stability are examined at different pH values. The influence of some parameters such as the initial dye concentration, pH value of the dye solution, electrolyte concentration, tripolyphosphate concentration, mixing time and speed on the encapsulation is examined. Congo Red removal efficiency and encapsulation capacity of chitosan nanoparticles were determined as above 98% and 5107 mg Congo Red/g chitosan, respectively. (C) 2016 Elsevier B.V. All rights reserved.Öğe One-pot green approach for rapid and effective anionic dye remediation: encapsulation within alginate nanocapsules(Wiley, 2024) Alver, Erol; Dogan, Deniz; Mert, Humeyra; Metin, Aysegul UlkuBACKGROUNDThe encapsulation technique was applied to efficiently eliminate Congo red (CR) from aqueous solutions. During the ionotropic gelation between calcium (Ca2+) ions and alginate (AL), CR was effectively entrapped within the AL nanocapsules in a one-step process. Suitable conditions for efficient CR removal via encapsulation were revealed by the systematic optimization of parameters including pH, time and stirring speed, etc.RESULTSAccording to the experimental observations, the stirring rate and temperature were found to have an insignificant effect on the encapsulation of CR molecules. When the pH value of the medium was 3, the highest level of encapsulation efficiency was achieved in a period of 15 min. At a preliminary CR concentration of 2000 mg L-1 and pH 3, the encapsulation efficiency was calculated at approximate to 98.9%, with an encapsulation capacity of 2800 mg dye g-1 AL. The zeta potential values of AL and CR/AL nanocapsules were determined to be +7.05 eV and -14.9 eV, respectively, and the results showed that the particles tended to agglomerate. TEM micrographs also showed that the nanocapsules were nanosized and agglomerated. Soil and UV degradation studies showed that the dye-entrapped nanocapsules degraded remarkably. These results highlighted the great potential of encapsulation for dye removal in economical and practical applications.CONCLUSIONEncapsulation was confirmed to be an economical and practical technique for effectively eliminating CR from aqueous solutions. Under UV light irradiation, the dye molecules entrapped within alginate nanocapsules displayed photodegradation. (c) 2024 Society of Chemical Industry (SCI).Öğe Phragmites australis as a new cellulose source: Extraction, characterization and adsorption of methylene blue(ELSEVIER, 2020) Kankilic, Gokben Basaran; Metin, Aysegul UlkuThe aim of this study was to investigate potential use of Phragmites australis in the production of cellulose microfibrils with chemical extraction process. Characterization of the natural P. australis and extracted fibrils were examined by FT-IR, XRD, FE-SEM, TGA, zeta potential and particle size distribution analyses indicating that amorphous polymer parts have been successfully moved away from the plant structure and cellulose content of P. australis was increased from 39.92% +/- 0.78% to 91.45 +/- 0.49%. Extracted cellulose samples showed microfibrillar structure based on FESEM images. The usability of cellulose microfibrils extracted from P. australis as an adsorbent was investigated in dye removal studies due to its abundant, eco-friendly and low-cost properties. Therefore, Methylene blue (MB) removal capacity of cellulose microfibrils from aqueous solution was tested and the effects of adsorption process parameters were evaluated in a controlled batch system. Maximum adsorption capacity (qm(max)) was found to be 54.9 mg/g and the microfibrils allowed MB removal over a wide pH range. Experimental data fit the both Langmuir and Freundlich isotherm models indicating multilayer adsorption. The adsorption process was better described with pseudo second-order kinetic model. In conclusion, P. australis is a good candidate in high purity cellulose microfibrils production as a natural material. Cellulose microfibrils are a potential alternative source which can be used as an adsorbent for wastewater treatment especially for cationic dye removal. Moreover, it can be used for production of cellulose microfibrils in various industrial applications. (C) 2020 Elsevier B.V. All rights reserved.Öğe Phragmites australis: An alternative biosorbent for basic dye removal(Elsevier Science Bv, 2016) Kankilic, Gokben Basaran; Metin, Aysegul Ulku; Tuzun, IlhamiThis study is aimed at investigating the removal of methylene blue (MB) from aqueous solutions using a reed species, Phrag-mites australis as an adsorbent. P. australis was modified by means of a chemical treatment, assuring the alteration of hydroxyl groups to sulphonyl groups. Experiments were performed in the batch mode to determine the adsorption dynamics of the modified and untreated P. australis. The impact of several influential parameters such as initial pH, initial dye concentration and contact time on the adsorption capacity of P. australis was evaluated. The adsorption capacity of raw P. australis was found to improve significantly by modification reaction. The maximum sorption capacities of the raw and modified biomass were found to be 22.7 mg/g and 46.8 mg/g at initial MB concentration of 250 ppm, biosorbent dosage 0.25 g and initial dye solution of pH of 6.5, respectively. Dye adsorption equilibrium data were fitted well to the Langmuir isotherm rather than the others. The rate of adsorption followed the pseudo second-order kinetic model. Thermodynamic parameters for both raw and modified biomass showed that the adsorption of MB was favorable and spontaneous. Results showed that both P. australis and its modified form have a potential as an eco-friendly adsorbent for the removal of methylene blue from aqueous solution. (C) 2015 Elsevier B.V. All rights reserved.Öğe Physicochemical and biological assessment of boron nitride nanosheets-reinforced poly(2-hydroxyethylmethacrylate) composite for biomedical applications(Elsevier, 2022) Dogan, Deniz; Metin, Aysegul UlkuResearch on mechanically advanced materials for biological applications involving load-bearing is in progress. Within this scope, this study is the first to propose the fabrication of bionanocomposites combining the different amounts of functionalized boron nitride nanosheets (f-BNNSs, 0-2.0 mg/mL) and poly(hydroxyethyl methac-rylate) (pHEMA). The pristine BN was exfoliated by microwave irradiation to access BNNSs at different powers and times. The as-exfoliated BNNSs were characterized by zeta-sizer, FTIR, XRD, and TEM, which showed that the BNNSs exhibited facile and processable features in tiny sizes. Bionanocomposites were fabricated by pho-topolymerization. The physical, chemical, and mechanical properties, hydrophilic behavior, and degradability of bionanocomposites were evaluated. The mechanical parameters such as Young's modulus and elongation per-centage at break showed that adding f-BNNSs up to 2.0 mg/mL significantly increased the mechanical strength of pHEMA without affecting the hydrophilicity, hemocompatibility, and cytotoxicity. Moreover, the hardness of pHEMA/f-BNNSs composites (38.56 MPa) was remarkably higher than that of pHEMA. There was no cytotoxicity recorded for fabricated bionanocomposites from the MTT assay. All nanocomposites exhibited superior anti-bacterial activities against E.coli and S.aureus compared with pHEMA. However, pHEMA/f-BNNSs composites were more effective against E.coli than S.aureus. While E.coli colonies was reduced 100% at all composites in an hour, S.aureus colonies was completely destroyed with pHEMA/1f-BNNSs and pHEMA/2f-BNNSs after 24 h in-cubation. The study's findings demonstrated that the mechanically improved pHEMA/f-BNNSs films could in-crease the application of pHEMA in biomedical fields.Öğe Poly (methyl vinyl ether-co-maleic acid) - Pectin based hydrogel-forming systems: Gel, film, and microneedles(Elsevier Science Bv, 2017) Demir, Yusuf Kemal; Metin, Aysegul Ulku; Satiroglu, Betul; Solmaz, Mehmet Ertugrul; Kayser, Veysel; Maeder, KarstenCross-linking of natural and synthetic polymers is widely explored to achieve the desired material properties (mechanical strength, drug loading capacity, swelling and erosion rates). However, the potential of polymers produced by crosslinking poly (methyl vinyl ether-co-maleic acid) (PMVE/IVIA) and pectin (PE) in pharmaceutics is mainly unexplored so far. We have investigated the effect of various esterification conditions and pectin content on the physicochemical properties. Materials have been characterized by fourier transform infrared, differential scanning calorimetry and scanning electron microscopy. In addition, swelling and bioadhesive features of PMVE/MA-PE hydrogel systems were investigated. A band shift for the carbonyl group from 1706 to 1776 cm(-1), and glass transition (Tg) increased from 55.4 +/- 0.9 degrees C to 119.5 +/- 0.3 degrees C confirmed the formation of esterification reaction within the cross-linked films. Cross-linked PMVE/MA:PE films with a ratio of 5 demonstrated a superior mass increase when compared to 2.5, 3.125, 3.75, 6.25, and 7.5 ratios of the same hydrogel film. Formulations containing PMVE/MA and pectin with a ratio of 3.75 showed superior bioadhesive features. For the first time, we engineered three-dimensional printing based swell-able microneedle arrays made out of cross-linked PMVE/MA-PE. Microneedle arrays height and aspect ratio were ranged from 702.5 +/- 11.9 mu m to 726 +/- 23.3 mu m and 3.12 +/- 0.20 to 3.29 +/- 0.21, respectively. Cross-linked PMVE/MA-PE Microneedle arrays (10-2, 24 h) indicated the least height loss, 22.33 +/- 4.15%, during axial compression test; whilst, transverse failure of cross-linked PMVE/MA-PE Microneedle arrays was varied from 0.15 +/- 0.05 to 0.25 +/- 0.04 N/needle. In conclusion, we obtained a novel cross-linked polymer system with promising features of drug delivery and bio-analytical applications. (C) 2017 Elsevier B.V. All rights reserved.Öğe 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, HakanThis 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.Öğe Recovery Studies on RDX from Decommissioned Munitions(Gazi Univ, 2024) Altin, Soner; Kose, Ozge; Metin, Aysegul Ulku; Turker, MehmetMunitions become obsolete due to the expiration of their shelf life, storage, or inappropriate conditions during use. In this study, it was aimed to recover and purify RDX from waste Composition-B (Comp-B) explosive, which is a mixture of 2,4,6-trinitrotoluene (TNT), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), which is the most commonly used as the main fusing agent in military munitions. Waste Comp-B samples were obtained from the munition in two different ways, and different RDX recovery percentages and purity were achieved. Comp-B was obtained both mechanically directly from the ammunition and through the recycling process by melting the main filling of the ammunition with hot water and steam method. TNT was removed from the samples obtained by both methods by utilizing the solubility differences of TNT and RDX in Toluene and RDX was obtained (rRDX). The recovery efficiency was 94% for Comp-B obtained by the mechanical method and 77% for the hot water/steam melting method. As a result of the subsequent purification process, RDX purity for both methods was calculated and determined to be more than 99%.Öğe Synthesis of magnesium diboride (MgB2) from its elements by mechanochemical method and usage as energetic agent(Gazi Univ, 2021) Canoz, Bilal; Metin, Aysegul Ulku; Guru, MetinAim The aim of this study is to synthesize of magnesium diboride using elemental magnesium (Mg) and elemental Boron (B) by mechanochemical method. Design & Methodology Magnesium diboride synthesis was carried out using elemental magnesium (Mg), and elemental boron (B).The products obtained were analyzed by using XRD and SEM-EDS. Originality Mg is an unstable element that can be easily oxidized. For this reason, MgB2, which has a stable structure, is thought to have an energy value that can be used in rocket fuels. Findings Optimum conditions are determined as follows: ball/powder mass ratio is 8/1, milling time is 7 hours, ratio of reactants are determined as 10% B excess and sinter process temperature is 650 degrees C. Conclusion After the production and purification steps, the yield was calculated as 87.1% and the calorific energy value of the obtained MgB2 was measured as 9.2 kcal/g. Declaration of Ethical Standards The author(s) of this article declare that the materials and methods used in this study do not require ethical committee permission and/or legal-special permission.
