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    Antioxidant Activity of Rumex conglomeratus P. Collected from Turkey
    (Asian Journal Of Chemistry, 2013) Kilic, Ismail; Yesiloglu, Yesim; Bayrak, Yuksel; Gulen, Sezer; Bakkal, Tahir
    Plants contain a wide variety of free radical scavenging molecules, such as flavonoids, anthocyanins, carotenoids, dietary glutathionine, vitamins and endogenous metabolites and such natural products are rich in antioxidant activities. Rumex conglomeratus P. is widely spread in Turkey and used as an anticonstipate in traditional medicine. In this study, the antioxidant activity of water extract of R. conglomeratus was evaluated using different antioxidant tests. In addition, carotenoid content and proline level of R. conglomeratus were also determined. The results were compared with natural and synthetic antioxidants. The results showed that R. conglomeratus contained naturally occuring antioxidant components and possessed antioxidant activity which may be attributed to its radical scavenging and metal chelating activities. It was concluded that R. conglomeratus might be a potential source of antioxidants.
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    The Effect of Problem-Based Learning Approach on Academic Success and Motivation in Science Education
    (Pegem Akad Yayincilik Egitim Danismanlik Hizmetleri Tic Ltd Sti, 2015) Kilic, Ismail; Moralar, Ayhan
    The aim of this study is to investigate the effect of problem-based learning approach of Matter and Heat unit taking place in science and technology course involved in the curriculum of the 6th grade on the students' academic success and motivation towards science and technology course. The research was designed and implemented according to pretest-posttest control group experimental model. 6-A class (N=16) attending Buyukkarakarli Primary School, Hayrabolu county, Tekirdag was determined as the experimental group intentionally biased by the researcher in the second semester of 2009-2010 academic year. 6-A class (N=20) attending Huseyin Korkmaz Primary School, Hayrabolu county, Tekirdag was determined randomly among three sections of the 6th class as the control group. While problem-based learning approach was implemented for the experimental group; traditional approaches were applied in the control group. While implementing problem-based learning approach for the experimental group, problem scenarios developed by the researcher were used. Academic Achievement Test and Science and Technology Course Motivation Scale were used as the data collection tools. By means of data analysis, it is found out that problem-based learning approach is more effective than traditional method in terms of developing academic success on science and technology course and motivation towards this course.
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    in vitro Antioxidant Activity and Total Phenolic Content of Various Extracts of Satureja hortensis L. Collected from Turkey
    (Asian Journal Of Chemistry, 2013) Yesiloglu, Yesim; Sit, Latifsah; Kilic, Ismail
    The antioxidant capacities of the acetone, ethanol and water extracts of leaves and flowers of S. hortensis were estimated using different antioxidant tests, including lipid peroxidation, reducing power, 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical scavenging, iron chelation, superoxide anion radical scavenging and hydrogen peroxide scavenging. The contents of antioxidant components in these extracts were also determined. Results showed that the highest contents of these components including phenols and flavonoids were found in water extract. This study verified that the water extract has strong antioxidant activities which were correlated with its high level of phenolics and flavonoids. This extract can be used as a source of potential antioxidant or functional food material.
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    In Vitro Antioxidant Activity of Various Extracts of Ginger (Zingiber officinale L.) Seed
    (Asian Journal Of Chemistry, 2013) Yesiloglu, Yesim; Aydin, Hatice; Kilic, Ismail
    The methanolic and ethanolic extracts from ginger (Zingiber officinale L.) seed (ZOS) were investigated for their antioxidant and radical scavenging activities in eight different assays, namely, total antioxidant activity, reducing power, 1,1-diphenyl-2-picryl-hydrazyl (DPPH) free radical scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, total flavonoid content, total phenolic Compound and metal chelating activities. Both methanolic extract and ethanolic extract of Zingiber officinale L. seed exhibited strong total antioxidant activity. These-various antioxidant activities were compared with synthetic antioxidants such as butylated hydroxyanisole, butylated hydroxytoluene, Trolox, alpha-tocopherol and ascorbic acid. The-Methanol:extract Zingiber officinale L. seed seed exhibited greater antioxidant capacity than that of ethanol.
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    Investigation on the Antioxidant Activity of Roots and Stem of Colchicum turcicum L.
    (Asian Journal Of Chemistry, 2014) Kilic, Ismail; Yesiloglu, Yesim; Bayrak, Yuksel
    Water and acetone extracts from Colchicum turcicum L. were investigated for their antioxidant and radical scavenging activities in four different assays, namely, total antioxidant activity, 1,1-dipenyl-2-picryl-hydrazyl (DPPH) free radical scavenging, hydrogen peroxide scavenging and ferrous chelating activities. Antioxidant activity, ferrous chelating and hydrogen peroxide scavenging activities of C. turcicum extracts showed dose dependence and increased with concentration of C. turcicum extract. At the same concentration (100 mu g/mL), water extract of C. turcicum (WECT) and acetone extract of C. turcicum (AECT) showed 53 and 48 % inhibition of lipid peroxidation of linoleic acid emulsion, respectively. On the other hand, butylated hydroxyanisole, butylated hydroxytoluene and ascorbic acid indicated inhibitions of 77, 71 and 59 % on the peroxidation of linoleic acid emulsion, respectively, at 50 mu g/mL. Also, the total phenolic content in both water extract of C. turcicum and acetone extract of C. turcicum were determined as catechol equivalents. The total phenolics content of water and acetone extracts were determined by the Folin-Ciocalteu procedure and 0.454 and 2.172 mg catechol equivalent of phenols was detected in 1 g water extract of C. turcicum and acetone extract of C. turcicum.
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    Kinetics and Thermodynamics of Cr(VI), Cu(II), and Ni(II) Adsorption on Activated Carbon Prepared from Rice Hulls
    (Taylor & Francis Inc, 2013) Bayrak, Yuksel; Topallar, Harika; Karagoz, Buse; Kilic, Ismail
    First, activated carbon was prepared by various ammonium compounds such as NH4NO3, NH4Cl, NH4Br, NH4I, NH4HCO3, and (NH4)(2)HPO4. The pore properties such as surface areas, pore volumes and pore sizes of them were compared under same activation conditions (600 degrees C, 5g of rice hull, 20g of ammonium compound, within a half-hour activation time). The highest surface area by Brunauer-Emmett-Teller (BET) method was obtained as 456.7667m(2)g(-1) by ammonium nitrate compared to other ammonium compounds, and then the kinetics and thermodynamics of Cr(VI), Cu(II), and Ni(II) ions removal from aqueous solutions on this activated carbon were studied. The adsorption data was found to follow second order kinetic model to explan the kinetics of Cr(VI), Cu(II), and Ni(II) ions adsorption, and rate constants were evaluated with the help of this kinetic model. Activation energy and other activation thermodynamic parameters (S, H, and G) were determined by means of the rate constants at different temperatures. Equilibrium data were fitted to the Langmuir and Freundlich adsorption isotherms. Freundlich isotherm best fits the experimental results. Thermodynamic parameters such as K-C, G, H, and S were also calculated. The positive value of S and negative values of G showed the spontaneous of this adsorption system, while the positive value of H pointed out this is an endothermic process.
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    Preparation of Rice Hull-Based Activated Carbon with Ammonium Nitrate
    (Asian Journal Of Chemistry, 2013) Kilic, Ismail; Bayrak, Yuksel; Topallar, Harika; Karagoz, Buse
    The present study deals with the preparation of rice hull-based activated carbon with ammonium nitrate. The obtained carbon was activated at temperatures between 400 and 900 degrees C. The rice hull-activated carbon presented a BET surface area of 456.77 m(2) g(-1) and a pore volume of 0.2406 cm(3) g(-1) at 600 degrees C. The adsorption and desorption average pore widths by BET method were found as 2.727 and 2.725 nm, respectively, whereas the Barret-Joyner-Halenda (BJH) adsorption and desorption average pore widths were 4.015 and 4.446 nm, respectively. Thus, it was found that rice hull-based activated carbon consisted of mesopores predominantly. These experimental results indicated the potential use of rice hull as a precursor in the activated carbon preparation process with ammonium nitrate. Moreover, the adsorption-desorption isotherm and the adsorption potential of the activated carbon that prepared at the optimum conditions were evaluated.
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    Spectrometric Studies on Antioxidant Activity of Pinus Nigra Resin In Vitro and Its Total Phenolic and Flavonoid Content
    (Bentham Science Publ Ltd, 2016) Kilic, Ismail
    The demand for novel effective antioxidant-based drugs has led to the evaluation of the antioxidant potential in several molecules derived from natural resources. In the current work, in vitro antioxidants of methnol extract of Pinus nigra resin (PNR) from Turkey were analyzed. The antioxidant activity of methanol extract of Pinus nigra resin was evaluated using different antioxidant assays such as total antioxidant activity, DPPH free radical scavenging activity, ferrous ions (Fe2+) chelating activity, reducing power, hydrogen peroxide (H2O2) scavenging activity, superoxide anion radical (O-2(center dot-)) scavenging activity and ABTS(.+) scavenging activity. In addition, the amounts of total phenolic and flavonoids were also determined. The extract showed 81% inhibition on peroxidation of linoleic acid emulsion. Like metal chelating, the reducing power, hydrogen proxide scavenging and ABTS(.+) scavenging activity of PNR depend on concentration, and increased with the increasing concentration of PNR. Our results indicated that the Pinus nigra resin showed the potential to be used as a natural antioxidant.
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    Spectroscopic studies on the antioxidant activity of ellagic acid
    (Pergamon-Elsevier Science Ltd, 2014) Kilic, Ismail; Yesiloglu, Yesim; Bayrak, Yuksel
    Ellagic acid (EA, C14H6O8) is a natural dietary polyphenol whose benefits in a variety of diseases shown in epidemiological and experimental studies involve anti-inflammation, anti-proliferation, anti-angiogenesis, anticarcinogenesis and anti-oxidation properties. In vitro radical scavenging and antioxidant capacity of EA were clarified using different analytical methodologies such as total antioxidant activity determination by ferric thiocyanate, hydrogen peroxide scavenging, 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH) scavenging, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging activity and superoxide anion radical scavenging, ferrous ions (Fe2+) chelating activity and ferric ions (Fe3+) reducing ability. EA inhibited 71.2% lipid peroxidation of a linoleic acid emulsion at 45 mu g/mL concentration. On the other hand, butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), alpha-tocopherol and ascorbic acid displayed 69.8%, 66.8%, 64.5% and 59.7% inhibition on the peroxidation of linoleic acid emulsion at the same concentration, respectively. In addition, EA had an effective DPPH center dot scavenging, ABTS(center dot+) scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, ferric ions (Fe3+) reducing power and ferrous ions (Fe2+) chelating activities. Also, those various antioxidant activities were compared to BHA, BHT, alpha-tocopherol and ascorbic acid as references antioxidant compounds. These results' suggested that EA can be used in the pharmacological, food industry and medicine because of these properties. (C) 2014 Elsevier B.V. All rights reserved.
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    Spectroscopic studies on the antioxidant activity of p-coumaric acid
    (Pergamon-Elsevier Science Ltd, 2013) Kilic, Ismail; Yesiloglu, Yesim
    p-coumaric acid (4-hydroxycinnamic acid), a phenolic acid, is a hydroxyl derivative of cinnamic acid. It decreases low density lipoprotein (LDL) peroxidation and reduces the risk of stomach cancer. In vitro radical scavenging and antioxidant capacity of p-coumaric acid were clarified using different analytical methodologies such as total antioxidant activity determination by ferric thiocyanate, hydrogen peroxide scavenging, 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH) scavenging, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) radical scavenging activity and superoxide anion radical scavenging, ferrous ions (Fe2+) chelating activity and ferric ions (Fe3+) reducing ability. p-Coumaric acid inhibited 71.2% lipid peroxidation of a linoleic acid emulsion at 45 mu g/mL concentration. On the other hand, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), alpha-tocopherol and ascorbic acid displayed 66.8%, 69.8%, 64.5% and 59.7% inhibition on the peroxidation of linoleic acid emulsion at the same concentration, respectively. In addition, p-coumaric acid had an effective DPPH center dot scavenging, ABTS(center dot+) scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, ferric ions (Fe3+) reducing power and ferrous ions (Fe2+) chelating activities. Also, those various antioxidant activities were compared to BHA, BHT, alpha-tocopherol and ascorbic acid as references antioxidant compounds. These results suggested that p-coumaric acid can be used in the pharmacological and food industry because of these properties. (C) 2013 Elsevier B.V. All rights reserved.
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    Teachers' and students' views about the applicability of the project-based learning approach in science courses in Turkey
    (Education Assoc South Africa, 2022) Kilic, Ismail; Ozel, Mehtap
    The aim with this study was to examine how, from the teachers' and students' perspectives, the project-based learning approach was applied in science and technology lessons. The research was conducted through a case study with qualitative research methods. The data of the study were obtained from semi-structured interviews with 38 students and 11 science and technology teachers. This data were analysed by descriptive analysis which is a qualitative data analysis method. The results of this study show that the teachers described the project-based learning approach as an inapplicable approach in schools. Teachers advised a reduction of curriculum content and a reduction in class sizes. We understood that the other phases of the project processes that started with the selection of project topics at school were done with the help of the students' families at home. It also became clear that during the evaluation process, the teachers took the students' own efforts into consideration. We determined that most of the students who participated in the projects in the science and technology course were free to choose their project subjects. It also became clear that students preferred to do projects in the science and technology course. At the end of the research report, suggestions based on the results of the research are made.