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Öğe Adsorptive removal kinetics of anionic dye onto chitosan films doped with graphene oxide: An in situ fluorescence monitoring(Taylor & Francis Inc, 2018) Kahya, Nilay; Bener, Semira; Kaygusuz, Hakan; Evingur, Gulsen Akin; Erim, F. BediaThe aqueous adsorption of a fluorescent dye (pyranine) onto crosslinked chitosan-graphene oxide composite films was studied. In situ fluorescence monitoring technique is introduced as easy and fast experimental technique to select optimal adsorbent conditions. The effect of ionic crosslinker on adsorption was studied with sodium tripolyphosphate, trisodium citrate, and sodium sulfate, respectively. Among the crosslinkers, it was realized that sodium sulfate crosslinked films showed a greater adsorption rate for pyranine than the other two types of crosslinked films. Recently, graphene oxide is of interest as a filler compound for many biopolymer applications due to its favorable thermal, mechanical and surficial properties. In the present study, graphene oxide incorporation increased adsorption rate of the dye and the mechanical strength of ionically crosslinked chitosan films. The adsorption behavior of the adsorbent was explained by a kinetic model. Samples were characterized using scanning electron microscopy, thermogravimetric analysis, swelling experiments and tensile testing method.Öğe Analysis of a Rare Honey Sample From Tuzluca/Iğdır Region(2020) Kaygusuz, HakanTurkey has a wide variety of honey products and most of the honeys are endemic. There are many endemic honey samples in Anatolia that have not been investigated yet. Since natural honey has special benefits due to its many bioactive ingredients, it is still a challenge to classify and characterize different honey samples. In this study, an endemic and rare honey sample from the mountainous and almost uninhabited region of Tuzluca, Iğdır is reported. Honey sample is characterized by the means of antioxidant and antidiabetic capacities, nitrite and nitrate content, fructose/glucose ratio. Results indicate that the reported honey sample has unique characteristics.Öğe Antibacterial nano cerium oxide/chitosan/cellulose acetate composite films as potential wound dressing(Pergamon-Elsevier Science Ltd, 2020) Kalaycıoğlu, Zeynep; Kahya, Nilay; Adımcılar, Veselina; Kaygusuz, Hakan; Torlak, Emrah; Akın-Evingür, Gülşen; Erim, F. BediaNovel chitosan and cellulose acetate polymer composites with nanosized cerium oxide were prepared as potential wound dressing materials. Chitosan and cellulose acetate are natural polymer derivatives with biocompatible properties. Both polymers can be dissolved in formic acid. The polymer composite was formed by solvent-casting method. The formed films were not soluble in water. In order to improve antibacterial, thermal, and mechanical properties of the composite material, films were loaded with nanosized cerium oxide. Films were characterized with thermogravimetric, scanning electron microscopy with energy-dispersive X-ray spectroscopy, mechanical, ultraviolet-visible light transmittance, water solubility, pH, moisture content, water vapor transmission rate, swelling, and antibacterial tests. The physical properties and antibacterial characteristics of the films are promising for further research as a potential wound covering material.Öğe Biopolymer-assisted green synthesis of functional cerium oxide nanoparticles(Springer International Publishing Ag, 2020) Kaygusuz, Hakan; Erim, F. BediaCerium oxide nanoparticles were synthesized by thermal decomposition of cerium alginate biopolymer gel at 450 degrees C, where alginate both acts as a precursor and a template. The synthesis is a green, facile and one-step method and the resulting nanoparticles have functionalized surface. The resulted material were characterized using X-ray diffraction for confirmation of cerium oxide, crystallite size analysis and grain size distribution. Transmission electron microscopy was used for the particle size determination, hydrodynamic size estimation was studied by dynamic light scattering and surface characteristics were analyzed using zeta potential measurements. Results show the presence of spherical particles with a size of < 5 nm. Having only a negative surface charge in such a wide pH range will ensure that the behavior of obtained nanoparticles in different environments is predictable. Isoelectric point of the synthesized material is significantly different from non-functionalized cerium oxide, and indicates the surface functionality, which is an important property for biocompatibility.Öğe Chemistry research in Europe: A publication analysis (2006-2016)(Sage Publications Ltd, 2021) Kaygusuz, HakanIn this article, chemistry research in 51 different European countries between years 2006 and 2016 was studied using statistical methods. This study consists of two parts: In the first part, different economical, institutional and citation parameters were correlated with the number of publications, citations and chemical industry numbers using principal components analysis and hierarchical cluster analysis. The results of the first part indicated that economical and geographical parameters directly affect the chemistry research outcome. In the second part, research in branches of chemistry and related disciplines such as analytical chemistry, polymer science and physical chemistry were analysed using principal components analysis and hierarchical cluster analysis for each country. Publication data were collected as the number of chemistry publications (in Science Citation Index-Expanded (SCI-E)) between years 2006 and 2016 in different chemistry subdisciplines and related scientific areas. Results of the second part of the study produced geographical and economical clusters of countries, interestingly, without addition of any geographical data.Öğe COVID-19 modeling based on real geographic and population data(Turkiye Klinikleri, 2023) Baysazan, Emir; Berker, A. Nihat; Mandal, Hasan; Kaygusuz, HakanBackground/aim: Intercity travel is one of the most important parameters for combating a pandemic. The ongoing COVID-19 pandemic has resulted in different computational studies involving intercity connections. In this study, the effects of intercity connections during an epidemic such as COVID-19 are evaluated using a new network model. Materials and methods: This model considers the actual geographic neighborhood and population density data. This new model is applied to actual Turkish data by means of provincial connections and populations. A Monte Carlo algorithm with a hybrid lattice model is applied to a lattice with 8802 data points. Results: Around Monte Carlo step 70, the number of active cases in Türkiye reaches up to 8.0% of the total population, which is followed by a second wave at around Monte Carlo step 100. The number of active cases vanishes around Monte Carlo step 160. Starting with İstanbul, the epidemic quickly expands between steps 60 and 100. Simulation results fit the actual mortality data in Türkiye. Conclusion: This model is quantitatively very efficient in modeling real-world COVID-19 epidemic data based on populations and geographical intercity connections, by means of estimating the number of deaths, disease spread, and epidemic termination.Öğe Effect of reinforcing materials on mechanical properties of composite material using Taguchi method(Journal of Physics: Conference Series, 2021) Owaid, Anmar Abdulazeez; Kaygusuz, Hakan; Mohammed, Farag MahelThe mechanical properties play an important role in the selection of suitable material in the manufacturing of boats. In this paper, the effect of glass fiber orientations and the fillers weight fraction on the mechanical properties of un saturated polyester composite material were studied. The glass fibers were used with (0/0, 0/90, 45/45) angles. The carbon filler used with (2.5%, 5%, 7.5%), while the aluminium oxide nano be used with (0%, 1%, 3%) weight fraction respectively. The standard Taguchi’s array L9 (33 ) was used. The signal to noise ratio and analysis of variance were introduced to analyze and estimate the optimal combination parameters. The results show that the mechanical properties improved with using the reinforcements. The glass fibers orientations angle presents the most parameter effect than the other parameters on the modulus of elasticity, tensile strength and impact strength with a contribution of 81.8%, 83.39% and 96.75% respectively. Followed by carbon and aluminium oxide nano. The optimum parameter with their levels for the highest modulus of elasticity was obtained at (0/90 fiber orientation, 5% carbon and 0% nano aluminium oxide). While the highest tensile strength and impact strength present with using (0/0 fiber orientation and 5% carbon). The experimental and expected results are very close, with an error ratio not exceeding 5%.Öğe Electric-field induced phase transitions in capillary electrophoretic systems(Aip Publishing, 2021) Kaygusuz, Hakan; Erim, F. Bedia; Berker, A. NihatThe movement of particles in a capillary electrophoretic system under electroosmotic flow was modeled using Monte Carlo simulation with the Metropolis algorithm. Two different cases with repulsive and attractive interactions between molecules were taken into consideration. Simulation was done using a spin-like system, where the interactions between the nearest and second closest neighbors were considered in two separate steps of the modeling study. A total of 20 different cases with different rates of interactions for both repulsive and attractive interactions were modeled. The movement of the particles through the capillary is defined as current. At a low interaction level between molecules, a regular electroosmotic flow is obtained; on the other hand, with increasing interactions between molecules, the current shows a phase transition behavior. The results also show that a modular electroosmotic flow can be obtained for separations by tuning the ratio between molecular interactions and electric field strength.Öğe Evaluation of some Turkish Salvia species by principal component analysis based on their vitamin B2, mineral composition, and antioxidant properties(Elsevier Science Bv, 2019) Gezek, Görkem; Hashemi, Parya; Kalaycıoğlu, Zeynep; Kaygusuz, Hakan; Sarıoğlu, Gözde; Döker, Serhat; Erim, F. BediaIn this study, 14 Turkish Salvia species, 12 of which are endemic, were characterized based on their vitamin B2, mineral, total phenolic contents, and antioxidant activities. Determination of vitamin B2 in Salvia species was achieved by a fast and sensitive capillary electrophoresis technique using a laser induced fluorescence (LIF) detector. All samples contain vitamin B2 ranging from 0.165 to 1.19 mg/100 g. Fifteen elements (Ca, K, Na, Mg, Fe, Mn, Zn, Li, Cu, Co, Al, V, Sr, Sn, and Ni) were determined in each Salvia sample by inductively coupled plasma-mass spectrometry (ICP-MS). Total phenolic contents of the Salvia samples, ranging from 11.8 to 119 mg gallic acid equivalents (GAE)/g, were determined using the Folin-Ciocalteu's method. The antioxidant activities were evaluated by 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical scavenging activity and ferric reducing antioxidant power assay (FRAP). Analysis data were evaluated by principal component analysis (PCA) and differentiation among Salvia species was shown.Öğe Foam-based antibacterial hydrogel composed of carboxymethyl cellulose/polyvinyl alcohol/cerium oxide nanoparticles for potential wound dressing(2024) Orhan, Burcu; Karadeniz, Duygu; Kalaycıoğlu, Zeynep; Kaygusuz, Hakan; Torlak, Emrah; Erim, F. BediaFoam-based wound dressing materials produced by dispersing gas phases in a polymeric material are soft, adapt to the body shape, and allow the absorption of wound exudate due to their porous structure. Most of these formulations are based on synthetic substances such as polyurethane. However, biopolymers have entered the field as a new player thanks to their biocompatible and sustainable nature. Incorporating biopolymers in formulations is gaining interest in scientific literature, and we extend this approach by adding antibacterial cerium oxide nanoparticles to biopolymer formulation. We introduce a novel biopolymer composite of carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), and cerium oxide nanoparticles (CeO2 NPs), namely PVA-CMC@CeO2. This mixture was first foamed and then cross-linked with sodium tetraborate solution, followed by a freeze-thaw process. After the novel material's spectroscopic, structural, and morphological characterization, we investigated its swelling, drug-delivery, antibacterial, and biodegradability properties PVA-CMC@CeO2 dressing effectively inhibits Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) growth and delivers the antibiotic drug silver sulfadiazine for up to 6 h. The antibacterial properties, good swelling, and drug release profile of the blend material show promising potential in wound care applications.Öğe Gain characteristics of short-length erbium-doped fiber amplifiers at extreme temperatures(Springer, 2021) Alnuwab, M. A.; Kaygusuz, HakanErbium-doped fiber amplifiers are used for amplifying optical signals. In this type of optical amplifier, the core of a silica fiber is doped with Er3+ ions. Here, the effects of temperature on the gain parameters for short-length erbiumdoped fiber amplifiers are simulated. Temperatures were selected over a wide range (-200 to +80 degrees C) for different ion densities to simulate extreme conditions, such as the presence of liquid nitrogen. The maximum gain occurs at temperatures close to 0 degrees C, and the Er3+ concentration also plays an important role.Öğe Graphene oxide/alginate quasi-cryogels for removal of methylene blue(Springer International Publishing, 2018) Balkız, Gizem; Pingo, Evridiki; Kahya, Nialy; Kaygusuz, Hakan; Bedia, Erim, F.Quasi-cryogelation technique is a simple yet effective technique for improving the adsorptive efficiency of biopolymer-based adsorbent materials. In this work, a biopolymer-based adsorbent material, graphene oxide alginate quasi-cryogel beads are reported. Alginate biopolymer was crosslinked and frozen at ? 21 °C in order to obtain a gel with cryogel-like microstructure. Graphene oxide was included in the bead formulation in order to enhance the adsorptive characteristics. Beads were characterized using Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and swelling experiments. Removal of the model cationic dye, methylene blue, was studied by batch adsorption method. It is found that the adsorption follows the Freundlich isotherm model and pseudo-first order kinetics with reaching an adsorption capacity of 122.26 mg/g in 60 min. Results indicate that the physisorption might be due to theinteractions between graphene oxide and methylene blue, in addition to electrostatic interactions. Moreover, quasi-cryogelation technique significantly improved the dye removal properties. © 2018, Springer International Publishing AG, part of Springer Nature.Öğe Mechanical,thermal and chemical properties of spent black tea doped concrete(Carl Hanser Verlag, 2020) Hanbay, Serap; Kaygusuz, HakanThe use of waste materials in concrete has been accelerated around the world recently. In this study, thermal and compressive strength properties of concrete doped with black tea waste are studied to assess the availability of using this type of waste in concrete. Black tea waste with 0.3 and 0.5 vol.-% were added to concrete mixtures. Thermal conductivity and effusivity of concrete with black tea waste were evaluated firstly, and load-bearing capacity of this biomass doped concrete were also investigated by the compressive test and Schmidt hammer test. The results showed that using black tea waste with 0.3 vol.-% slightly decreased the compressive strength of concrete whereas there was a considerable decrease in thermal conductivity. However, using black tea waste with 0.5 vol.-% causes an obvious decrease in compressive strength and a decrease in thermal conductivity of concrete which is not directly proportional with the amount of black tea. Therefore, with a small toleration of loss of compressive strength, black tea waste doped concrete can be produced with high volume fractions in order to have concrete samples with good thermal insulation for research purposes.Öğe Novel approaches for COVID-19 diagnosis and treatment: A nonsystematic review(TÜBİTAK, 2021) Garip Ustaoğlu, Şebnem; Kaygusuz, Hakan; Bilgin, Mehmet Dinçer; Severcan, FerideSince COVID-19 pandemic has been continuously rising and spreading, several original contributions and review articles on COVID-19 started to appear in the literature. The review articles are mainly focus on the current status of the pandemic along with current status of the corona diagnosis and treatment process. Due to some disadvantages of the currently used methods, the improvement on the novel promising diagnosis and treatment methods of corona virus is very important issue. In this review, after briefly discussing the status of current diagnosis and treatment methods, we present to the scientific community, novel promising methods in the diagnosis and treatment of COVID-19. As with other novel approaches, first, the diagnosis potential of mass spectroscopy and optical spectroscopic methods such as UV/visible, infrared, and Raman spectroscopy coupled with chemometrics will be discussed for the corona virus infected samples based on the relevant literature. In vibrational spectroscopy studies, due to complexity of the data, multivariate analysis methods are also applied to data. The application of multivariate analysis tools that can be used to extract useful information from the data for diagnostic and characterisation purposes is also included in this review. The reviewed methods include hierarchical cluster analysis, principal component analysis, linear and quadratic discriminant analysis, support vector machine algorithm, and one form of neural networks namely deep learning method. Second, novel treatment methods such as photodynamic therapy and the use of nanoparticles in the in-corona virus therapy will be discussed. Finally, the advantages of novel promising diagnosis and treatment methods in COVID-19, over standard methods will be discussed. One of the main aims of this paper is to encourage the scientific community to explore the potential of this novel tools for their use in corona virus characterization, diagnosis, and treatmentÖğe Sustainable alginate-carboxymethyl cellulose superabsorbents prepared by a novel quasi-cryogelation method(Springer, 2022) Orhan, Burcu; Kaygusuz, Hakan; Erim, F. BediaThe research in biopolymer-based superabsorbents is gaining importance in the green chemistry feld thanks to their environmentally friendly properties. In this study, a biopolymer-based superabsorbent made of calcium ion crosslinked alginate/ carboxymethyl cellulose composite was prepared by a new quasi-cryogelation process, where the complete ionic gelation takes place before the freezing step, in contrast to the conventional cryogelation technique in which gelation occurs under semi-frozen conditions. Thanks to the facile quasi-cryogelation method, the morphology of the gels changed and a signifcant increase in water absorption properties has been achieved. The swelling properties of the material were investigated in distilled water and diferent physiological fuids. Results show that the proposed material shows good water absorption property where a water absorption of 2343% was reached and even after fve cycles this value was 1200%. As a result, this study reports a biopolymer-based sustainable superabsorbent which is appropriate for various applications such as the removal of pollutants from water or diaper production.Öğe The effect of weekend curfews on epidemics: A Monte Carlo simulation(2021) Kaygusuz, Hakan; Berker, A. NihatThe ongoing COVID-19 pandemic is being responded with various methods, applying vaccines, experimental treatment options, total lockdowns or partial curfews. Weekend curfews are among the methods for reducing the number of infected persons and this method is practically applied in some countries such as Turkey. In this study, the effect of weekend curfews on reducing the spread of a contagious disease, such as COVID-19, is modeled using a Monte Carlo algorithm with a hybrid lattice model. In the simulation setup, a fictional country with three towns and 26,610 citizens were used as a model. Results indicate that applying a weekend curfew reduces the ratio of ill cases from 2 0.23 to 0.15. The results also show that applying personal precautions such as social distancing is important for reducing the number of cases and deaths. If the probability of disease spread can be reduced to 0.1, in that case the death ratio can be minimized down to 0.Öğe Türkiye'ye özgü bitki ve gıda örneklerinin temel bileşenler analiziyle sınıflandırılması(Altınbaş Üniversitesi, 2018) Kaygusuz, HakanTemel bileşenler analizi (İng. Principal component analysis, PCA) çok sayıda değişkenin temsil ettiği bir verinin matematiksel bir dönüşüm ile toplam varyansı açıklayabilen temel bileşenlere geçirilmesini konu alan istatistiksel bir yöntemdir. Pek çok alanda olduğu gibi kimyasal verilere de uygulanabilen bu yöntemle, özellikle biyolojik türler için büyük önem taşıyan sınıflandırma kolayca yapılabilmektedir. Bu derleme makalesinde, Türkiye’ye özgü gıda ve bitki örneklerinin konu edildiği temel bileşenler analizi çalışmalarına değinilmiş ve sonuçları incelenmiştir. Bunlara ek olarak, bu tür çalışmaların yararı ve önemi hakkında tartışılmıştır.
