Sahin H.,Giresun University
Journal of Enzyme Inhibition and Medicinal Chemistry | Year: 2016
The aim of this study was to evaluate new natural inhibitor sources for the enzymes urease and xanthine oxidase (XO). Chestnut, oak and polyfloral honey extracts were used to determine inhibition effects of both enzymes. In addition to investigate inhibition, the antioxidant capacities of these honeys were determined using total phenolic content (TPC), ferric reducing antioxidant power (FRAP), and DPPH radical scavenging activity assays. Due to their high phenolic content, chestnut and oak honeys are found to be a powerful source for inhibition of both enzymes. Especially, oak honeys were efficient for urease inhibition with 0.012-0.021 g/mL IC50 values, and also chestnut honeys were powerful for XO inhibition with 0.028-0.039 g/mL IC50 values. Regular daily consumption of these honeys can prevent gastric ulcers deriving from Helicobacter pylori and pathological disorders mediated by reactive oxygen species. © 2015 Informa UK Ltd.
Polat R.,Giresun University |
Cakilcioglu U.,Firat University |
Satil F.,Balikesir University
Journal of Ethnopharmacology | Year: 2013
Ethnopharmacological relevance This study has identified not only the wild plants collected for medical purposes by local people of Solhan District in the Eastern Anatolia Region, but also the uses and local names of these plants. It tried to provide a source for researchers studying in ethnobotany, pharmacology and chemistry by comparing the information obtained from traditionally used herbs with previous laboratory studies. Aim of the study This study aims to identify wild plants collected for medical purposes by the local people of Solhan District located in the Eastern Anatolia Region of Turkey and to determine the uses and local names of these plants. Materials and methods A field study had been carried out for a period of approximately 2 years (2011-2012). During this period, 214 vascular plant specimens were collected. Demographic characteristics of participants, names of the local plants, their utilized parts and preparation methods were investigated and recorded. The plant species were collected within the scope of the study; herbarium materials were prepared; and the specimens were entitled. In addition, the relative importance value of the species was determined and informant consensus factor (FIC) was calculated for the medicinal plants included in the study. Our research area also includes people with Kurdish and Zaza ethnic origins. Results 82 plants were found to be used for medical purposes before in the literature analysis of the plants used in our study, while 9 plants were found to have no literature records. The most common families are Asteraceae (12 plants), Rosaceae (10 plants), and Lamiaceae (9 plants). The medicinal uses of Anthriscus cerefolium (L.) Hoffm., Arum elongnatum Steven, Astragalus lamarckii Boiss., Chaerophyllum bulbosum L., Crataegus atrosanguinea Pojark., Hordeum bulbosum L., Pastinaca armena Fisch. & Mey., Prunus kurdica Fenzl ex Fritsch, Sium sisarum L. var. lancifolium (M. Bieb.) Thell. that we found were used in our study area and recorded for the first time. No information could be obtained regarding the names of two wild plants that are being used in Solhan. In Turkey, local plant names display differences especially due to local dialects. The plants used in Solhan are known by the same or different local names in various parts of Anatolia. Conclusion In the research area, local people were found to use 82 plants from 31 families for curative purposes. The respondents of the questionnaire are Turkish citizens, with various ethnic backgrounds. Mean age of the respondents was 55 years. These plants are used in the treatment of many diseases. Comparison of the data obtained in this study with the experimental data obtained in the previous laboratory studies derived from the plants growing in Solhan proved ethnobotanical usages to a great extent. Literature review indicated that the curative plants that grow in Solhan are used in different parts of the world for the treatment of similar diseases. These plants, used for the treatment of various diseases, are abundantly found in this region. Drying of the medicinal plants enabled the local people to use them in every season of the year. © 2013 Published by Elsevier Ireland Ltd.
Ultay N.,Giresun University |
Calik M.,Karadeniz Technical University
Journal of Science Education and Technology | Year: 2012
Context-based chemistry education aims at making connections between real life and the scientific content of chemistry courses. The purpose of this study was to evaluate context-based chemistry studies. In looking for the context-based chemistry studies, the authors entered the keywords 'context-based', 'contextual learning' and 'chemistry education' in well-known databases (i. e. Academic Search Complete, Education Research Complete, ERIC, Springer LINK Contemporary). Further, in case the computer search by key words may have missed a rather substantial part of the important literature in the area, the authors also conducted a hand search of the related journals. To present a detailed thematic review of context-based chemistry studies, a matrix was used to summarize the findings by focusing on insights derived from the related studies. The matrix incorporates the following themes: needs, aims,methodologies, general knowledge claims, andimplications for teaching and learning, implications for curriculum development and suggestions for future research. The general knowledge claims investigated in this paper were: (a) positive effects of the context-based chemistry studies; (b) caveats, both are examined in terms of students' attitudes and students' understanding/cognition. Implications were investigated for practice in context-based chemistry studies, for future research in context-based chemistry studies, and for curriculum developers in context-based chemistry studies. Teachers of context-based courses claimed that the application of the context-based learning approach in chemistry education improved students' motivation and interest in the subject. This seems to have generated an increase in the number of the students who wish to continue chemistry education at higher levels. However, despite the fact that the majority of the studies have reported advantages of context-based chemistry studies, some of them have also referred to pitfalls, i. e. dominant structure of out-of-school learning, tough nature of some chemistry topics, and teacher anxiety of lower-ability students. © 2011 Springer Science+Business Media, LLC.
Kacal M.R.,Giresun University
Radiation Physics and Chemistry | Year: 2014
Energy dispersive X-ray fluorescence technique (EDXRF) has been employed for measuring L3-subshell absorption jump ratios, rL3 and jump factors, JL3 for high Z elements. Jump factors and jump ratios for these elements have been determined by measuring L3 subshell fluorescence parameters such as L3 subshell X-ray production cross section σL3, L3 subshell fluorescence yield, ωL3, total L3 subshell and higher subshells photoionization cross section σLT. Measurements were performed using a Cd-109 radioactive point source and an Si(Li) detector in direct excitation experimental geometry. Measured values for jump factors and jump ratios have been compared with theoretically calculated and other experimental values. © 2014 Elsevier Ltd.
Yalcin E.,Giresun University
Environmental technology | Year: 2011
Pseudomonas putida RW-II isolated from petroleum refinery wastewater was tested for hydrocarbon degradation potential in the presence of polycationic surfactant, cetyl trimethylammonium bromide (CTAB). The effects of CTAB on growth profile, cell surface hydrophobicity, cell adhesion, zeta potential and hydrocarbon biodegradation were investigated. The addition of CTAB had a significant effect on the growth profile of RW-II and the growth was increased 1.11 times in hexadecane containing medium. In the presence of CTAB, the growth of Pseudomonas putida RW-II increased about 14.4%. The zeta potential of Pseudomonas putida RW-II decreased significantly when CTAB was added to the medium. The addition of CTAB not only decreased the zeta potential of surface, but also significantly increased the hydrophobicity of the cell surface. The degradation rate of hexadecane, anthracene and naphthalene was observed as 64.8%, 46% and 56% at the end of 120 h, respectively. Biodegradation of hexadecane, anthracene and naphthalene was enhanced 1.16, 1.15 and 1.08 times at 40 mg/L CTAB addition, respectively. The increase in biodegradation resulted from improved interaction between the hydrocarbon and microorganism derived from the increased adhesion. Thus, the use of CTAB has been proposed to be a valuable effect to enhance the biodegradation of hydrocarbons.
Guney M.S.,Giresun University
Renewable and Sustainable Energy Reviews | Year: 2011
In this study was presented the valid equations for energy conversion system from water currents analogous to wind power system. Hydrokinetic technology may be divided into two categories such as horizontal and vertical system. Application of the systems is possible to marine, and river currents. Each system has different performance coefficient. Hydrokinetic energy conversion systems shows lower power coefficient. The existing measures with the purpose of increasing of performance coefficient have been presented. Additional suggestions have been put forward. Future perspectives for application improvement and working fields of different kind have been given. © 2011 Elsevier Ltd. All rights reserved.
Guney M.S.,Giresun University
Renewable and Sustainable Energy Reviews | Year: 2016
Solar energy conversion and its application methods varies in wide range from passive solar to heat building to complex concentrated form to generate electricity. It is crucial to know these structures in detail and to classify them in methodical order. The constituent mechanism of primary energy sources have been briefly mentioned. Hereafter the classification of renewable energies, various application methods of solar power, the amount of solar energy falling on the earth, the main effects created by solar energy, and energy conversion methods, inclusively concentrated solar power, have been discussed. © 2015 Elsevier Ltd. All rights reserved.
Ozen T.,Giresun University
Grasas y Aceites | Year: 2010
The antioxidative activity of the 80% ethanol extract obtained from eleven commonly consumed wild edible plants was determined according to the phosphomolybdenum method, reducing power, metal chelating, superoxide anion and free radical scavenging activity and compared to standard compounds such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and trolox. Total phenolic compounds, flavonoids, and anthocyanins in the extracts were also measured. Trachystemon orientalis, Vaccinium mrytillus, Rumexacetosella Polygonum amphibium, Beta vulgaris, and Similax Excelsa had the highest antioxidant capacities. overall results showed that these plants can serve as good sources of bioactive polyphenols in the human diet and can be regarded as good candidates for nutritional supplement formulations due to their high concentrations of total phenolic compounds, flavonoids and anthocyanins as well as their strong antioxidant activity.
Baris B.,Giresun University
Physica B: Condensed Matter | Year: 2013
Al/rubrene/p-Si Schottky diode has been fabricated by forming a rubrene layer on p type Si by using the spin coating method. The frequency dependent capacitance-voltage (C-V-f) and conductance-voltage (G-V-f) characteristics of Al/rubrene/p-Si Schottky diyotes has been investigated in the frequency range of 5 kHz-500 kHz at room temperature. The C-V plots show a peak for each frequency. The capacitance of the device decreased with increasing frequency. The decrease in capacitance results from the presence of interface states. The plots of series resistance-voltage (Rs-V) gave a peak in the depletion region at all frequencies. The density of interface states (N ss) and relaxation time (t) distribution profiles as a function of applied voltage bias have been determined from the C-V and G-V measurements. The values of the Nss and τ have been calculated in the ranges of 8.37 × 1011 -4.85 × 1011 eV-1 cm-2 and 5.17 × 10-6-1.02 × 10-5 s, respectively. © 2013 Elsevier B.V. All rights reserved.
Baris B.,Giresun University
Physica B: Condensed Matter | Year: 2014
In present paper, the device parameters of tin oxide/n-Si(1 0 0) structure have been determined by means of capacitance-voltage (C-V) and conductance-voltage (G-V) measurements between 500 Hz and 1 MHz and current-voltage (I-V) measurements between -2 and +3 V at 300 K. This device has denoted good rectifying behavior and the I-V data could be described by thermionic emission (TE) technique. The values of ideality factor (n) and barrier height (ΦB) for the sample have been determined to be 3.724 and 0.624 eV, respectively. The measured values of capacitance and conductance for the series resistance under all the biases have been corrected influence to calculate the real values of capacitance and conductance. The frequency dependence of the capacitance may be attributed to trapping states. Interface trap states of the MOS device increased by decreasing the frequency and were calculated as 1.12×1011 and 6.62×1011 eV-1 cm-2 for 1 MHz and 100 kHz, respectively. Several important device parameters such as barrier height (ΦB), fermi energy (EF), diffusion voltage (VD), donor carrier concentration (ND) and space charge layer width (WD) for the device have been obtained between 100 kHz and 1 MHz. © 2014 Elsevier B.V. All rights reserved.