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Öğe Dentinal tubule occluding capability of nano-hydroxyapatite; The in-vitro evaluation(Wiley, 2018) Baglar, Serdar; Erdem, Umit; Dogan, Mustafa; Turkoz, MustafaIn this in-vitro study, the effectiveness of experimental pure nano-hydroxyapatite (nHAP) and 1%, 2%, and 3% F doped nano-HAp on dentine tubule occlusion was investigated. And also, the cytotoxicity of materials used in the experiment was evaluated. Nano-HAp types were synthesized by the precipitation method. Forty dentin specimens were randomly divided into five groups of; 1no treatment (control), 2specimens treated with 10% pure nano-HAp and 3, 4, 5 specimens treated with 1%, 2%, and 3% F(-)doped 10% nano-HAp, respectively. To evaluate the effectiveness of the materials used; pH, FTIR, and scanning electron microscopy evaluations were performed before and after degredation in simulated body fluid. To determine cytotoxicity of the materials, MTT assay was performed. Statistical evaluations were performed with F and t tests. All of the nano-HAp materials used in this study built up an effective covering layer on the dentin surfaces even with plugs in tubules. It was found that this layer had also a resistance to degradation. None of the evaluated nano-HAp types were have toxicity. Fluoride doping showed a positive effect on physical and chemical stability until a critical value of 1% F-. The all evaluated nano-HAp types may be effectively used in dentin hypersensitivity treatment. The formed nano-HAp layers were seem to resistant to hydrolic deletion. The pure and 1% F(-)doped nano-HAp showed the highest biocompatibility thus it was assessed that pure and 1% F(-)doped materials may be used as an active ingredient in dentin hypersensitivity agents.Öğe Determining the lowest sulfur detection limit in diesel fuel by ultraviolet fluorescence(TAYLOR & FRANCIS LTD, 2020) Dogan, MustafaThis 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.Öğe EFFECTS OF HIGH VOLTAGE ELECTRIC FIELD (HVEF) TREATMENTS ON GERMINATION AND SEEDLING GROWTH OF FIELD PEA (Pisum arvense L.) SEEDS(Parlar Scientific Publications (P S P), 2021) Erol, Taskin; Kara, Kamil; Yilmaz, Ozlem Ince; Dogan, MustafaField pea is an important cool-season legume crop that is grown on over 6 million hectares worldwide. P. arvense is a variety used commonly as forage pea due to its digestibility and highly nutritious content suitable for feeding livestock. Despite various types of electric field treatments are investigated for the improvement of widely consumed crops, studies are still very limited. In this study, field pea seeds were treated with HVEF of 50, 100 and 200 kV/m intensities for 3 different durations (1, 5 and 10 minutes). Germination and seedling growth parameters examined were germination percentage, root and shoot lengths and dry weights. Germination percentage was 96.25% for control, and oscillated +/- 1.5% in treatments with no significance. 50 and 100 kV/m treatments enhanced root lengths up to 10.5% in 5 min-100 kV/m treatments. Although non-significant, shoot lengths also increased especially in 100 kV/m treatments up to 16.2%. The most significant effect was determined in root dry weights which improved in all treatments of 50 and 100 kV/m except 10 min-50 kV/m treatment. 200 kV/m treatments slightly reduced the growth of seedlings. This study shows that HVEF treatments are effective in enhancing seedling growth of field pea seeds and have the potential to be used in seed technologies.Öğe Hydroxyapatite-based nanoparticles as a coating material for the dentine surface: An antibacterial and toxicological effect(ELSEVIER SCI LTD, 2020) Erdem, Umit; Dogan, Mustafa; Metin, Aysegul U.; Baglar, Serdar; Turkoz, Mustafa B.; Turk, Mustafa; Nezir, SaffetIn this study, nano sized hydroxyapatite (nHAp) and Ag(I) doped hydroxyapatite (Ag-nHAp) particles were synthesized by the precipitation method and used as a coating material for remineralization on caries-affected dentine samples. Characterization studies of both the synthesized hydroxyapatite-based particles and the coated dentine samples were performed using instrumental techniques such as SEM and FFIR, and then toxicity and antibacterial properties were also evaluated. It was observed that dentine samples were effectively coated by both nHAp and Ag center dot nHAp particles which have no toxic effects. Furthermore, the costing of nano-hydroxyapatite on dentine samples positively contributed to the viability of L929 fibroblast cells and also provided an antibacterial effect against to bacteria such as S. mutants, C. albicans and E. coli bacteria that are most frequently caused caries in the teeth. While all type of bacteria was eliminated by the nHAp coated dentine samples at 24th, Ag-nHAp coated dentine samples removed to all bacteria type at 1st.Öğe Impacts Of High Voltage Electric Field (Hvef) Applications On Germination And Seedling Growth Of Seed (Triticum Aestivum L.) With Analysis By Fourier Transform Infrared (Ftir) Spectroscopy(Parlar Scientific Publications (P S P), 2018) Ince-Yilmaz, Ozlem; Erol, Taskin; Kara, Kamil; Dogan, Mustafa; Erdem, UmitWheat is an important widely grown cereal that its grains used worldwide as a staple food. In this study, germination and seedling growth characteristics of grains of Triticum aestivum, the most widely grown species of the genus, in response to HVEF applications were studied. Three different intensities (50, 100 and 200 kV/m) were applied for 1, 5 and 10 min durations. Germination percentages were not affected by treatments, while germination speeds were inhibited by high intensities at long durations. Maximum enhancement in seedling growth measures which were given as root and shoot lengths and dry weights was determined for 5 min 50 kV/m treatment, where increases in average seedling lengths and dry weights were 34.2 % and 26.1 %, respectively. 1 min durations of treatments were also highly improved seedling growth, particularly at root measures. ATR technique was used to analyze the roots and first foliage leafs of treated seeds at FTIR spectroscopy. FTIR results supported that HVEF treatment could be a useful tool for enhancement of wheat seedling growth in early stages of development.Öğe Polymer-layered oxygen sensor design and testing(Springer, 2021) Dogan, MustafaSensors 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.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 Thermal, morphological, and spectral changes after Er, Cr:YSGG laser irradiation at low fluences on primary teeth for caries prevention(WILEY, 2021) Erkmen Almaz, Merve; Ulusoy, Nur Burcu; Akbay Oba, Aylin; Erdem, Umit; Dogan, MustafaThe aim of this study was to determine the temperature increase in the pulp chamber and possible thermal effects on molecular structure of primary teeth during the irradiation with Er,Cr:YSGG laser. Primary central incisors were divided into three groups (n = 20). Labial surfaces in each group were irradiated by Er,Cr:YSGG laser within different power and frequencies as following groups: I: 0.25 W, 20 Hz, II: 0.50 W, 20 Hz, III: 0.75 W, 20 Hz. A thermocouple was placed inside the pulp chamber so that the temperature increments were recorded during the enamel irradiation. Morphological changes of enamel surfaces were experimentally evaluated by SEM. Fourier-transform infrared spectroscopy and RAMAN analyses were carried out to determine the differentiations in the molecular structure. The experimental results obtained were analyzed statistically by means of one-way analysis of variance. Statistically significant differences were detected between groups (p < .05). Group III exhibited the highest values for the temperature parameters. Besides, the conical craters, cracks, and formation of ablation areas were observed for all the groups. Also, it was obtained that the hydroxyapatite lost the hydroxyl ions due to the thermal effect of the laser. Temperature rise throughout the Er,Cr:YSGG laser irradiation for prevention of primary enamel demineralization presented a positive correlation with the laser output power level. The formations of adverse morphological and spectral changes were detected on the surface of teeth after the laser application. On this basis, the Er,Cr:YSGG laser applications should be treated with much more caution considering enamel surface and pulpal tissues in primary teeth.Öğe Ultraviolet light accelerates the degradation of polyethylene plastics(Wiley, 2021) Dogan, MustafaPolyethylene 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.
