Garoufalis C.S.,University of Patras |
Garoufalis C.S.,Technological Educational Institute Tei Of Ionian Islands |
Poulopoulos P.,University of Patras |
Bouropoulos N.,University of Patras |
And 3 more authors.
Physica E: Low-Dimensional Systems and Nanostructures | Year: 2017
Thin iron films in the thickness range 0.7–48 nm have been deposited on high quality Corning glass and Si(100) substrates by radio frequency magnetron sputtering. The films were then oxidized by annealing at temperatures of 400−450 °C in a furnace in air. X-ray diffraction experiments revealed the formation of single-phase α-Fe2O3. The films were continuous and present negligible surface roughness. Ultraviolet-visible light absorption spectroscopy has shown a blue shift of both, the indirect and direct band gaps of hematite. The experimental results are interpreted as evidences of quantum confinement effects. This is facilitated by theoretical calculations based on Hartree Fock approximation as applied for an electron-hole system, in the framework of effective mass approximation. The agreement between theory and experiment supports the quantum confinement interpretation. © 2017 Elsevier B.V.
Salta K.,National and Kapodistrian University of Athens |
Gekos M.,National and Kapodistrian University of Athens |
Koulougliotis D.,Technological Educational Institute TEI of Ionian Islands
Chemistry Education Research and Practice | Year: 2012
This study aims at identifying factors that influence students' choice not to pursue a chemistry-related career by analyzing the experiences of secondary education chemistry teachers in Greece and of Greek adults who have not pursued studies related to science. Data collection was done with the method of individual structured interviews. The comparative analysis of the answers given by 10 adults and 10 chemistry teachers, shows that there is a noteworthy agreement between the factors pointed out by the two independent groups. These factors - proposed to form an interconnected grid - are related to the following issues: the nature of school chemistry, the instructional content and context, the students' characteristics and the status of chemistry in the Greek educational system and Greek society. This journal is © The Royal Society of Chemistry.
Tsasi G.,National and Kapodistrian University of Athens |
Sokovic M.,University of Belgrade |
Ciric A.,University of Belgrade |
Eriotou E.,Technological Educational Institute Tei Of Ionian Islands |
And 3 more authors.
Records of Natural Products | Year: 2016
The essential oils (EOs) from the leaves and the flowers of Smyrnium olusatrum L., growing wild in the island of Cephalonia (Greece), were analyzed by GC-FID and GC-MS. Fifty nine constituents, which accounted for 90.3% (fl) and 97.1% (lvs) of the oils, were identified. Furanodiene, germacrone and furanoeremophil-1-one were the major constituents in both essential oils; they were also isolated from the flowers essential oil and identified using spectroscopic methods, ie. 1D and 2D NMR, GC-MS. In addition β-myrcene (11.7%) and β-phellandrene (5.2%) were main constituents in the essential oil of the leaves. The essential oils and the pure isolates were evaluated for antifungal activity against Aspergillus fumigatus, A. versicolor, A. ochraceus, A. niger, Trichoderma viride, Penicillium funiculosum, P. ochrochloron, P. verucosum var. cyclopium by using the microdilution method and proved to possess significant antifungal effect. Among them, (+) furanoeremophil-1-one was particularly active with MIC values in the range of 0.0008-0.125 mg/mL and MFC values of 0.025-0.050 mg/mL and proved more effective than the commercial mycotics ketoconazole and bifonazole used as positive controls. © 2015 ACG Publications. All rights reserved.
Kachrimanidou V.,Agricultural University of Athens |
Kopsahelis N.,Agricultural University of Athens |
Kopsahelis N.,Technological Educational Institute TEI of Ionian Islands |
Vlysidis A.,Agricultural University of Athens |
And 5 more authors.
Food and Bioproducts Processing | Year: 2016
Crude enzyme produced via solid state fermentation using the fungal strain Aspergillus oryzae was used to lyse cells of Cupriavidus necator, enabling the recovery of poly(3-hydroxybutyrate-co-3-hydroxyvalerate), P(3HB-co-12 mol% 3HV). A central composite design was employed in order to optimize the temperature and the pH value leading to the highest lysis of C. necator cells (88.9 ± 0.4%) and the optimal hydrolysis of protein contained in bacterial cells. Enzymatic lysis of bacterial cells was also carried out at the optimum temperature and uncontrolled pH value leading to P(3HB-co-12 mol% 3HV) recovery yield and purity of 98% and 96.7%, respectively. The bacterial cell lysate obtained after the separation of P(3HB-co-12 mol% 3HV) granules was evaluated as nutrient-rich supplement together with crude glycerol for the production of poly(3-hydroxybutyrate) in shake flask cultures. This novel downstream separation process could be integrated in a sunflower-based biorefinery reducing the cost of poly(hydroxyalkanoate) recovery and fermentation medium formulation. © 2016 Institution of Chemical Engineers
Koulougliotis D.,Technological Educational Institute Tei Of Ionian Islands |
Koulougliotis D.,Greek National Center For Scientific Research
Photosynthetica | Year: 2010
Progressive microwave power saturation (P1/2) measurements have been performed on the tyrosine D radical (YD •) of photosystem II (PSII) in order to examine its relaxation enhancement by the oxygen-evolving complex (OEC) poised to the reduced S-1 and S-2 oxidation states by NO treatment. Analysis of the power saturation curves showed that the S-1 oxidation state of the OEC does not enhance the relaxation of YD •: it therefore possesses a diamagnetic ground state. In contrast, the Mn(II)-Mn(III) multiline electron paramagnetic resonance (EPR) signal characteristic of the S-2 oxidation state of the OEC was shown to provide a relaxation enhancement pathway for YD •, however less efficient relative to the one provided by the S2-state multiline EPR signal. We also examined the YD • relaxation enhancement characteristics of the EPR-silent oxidation state produced after brief (1-5 min) dark incubation at 0°C of a PSII sample poised to the EPRactive S-2 state. This EPR-silent oxidation state denoted as "0°C incubation" state was shown to possess remarkably similar P1/2 values with the EPR-active S-2 state in the overall examined temperature range (6-20 K). In addition, these values remained unchanged after successive cycles of the OEC between the EPR-active S-2 state and the "0°C incubation" state. The data presented in this work point to the conclusion that the "0°C incubation" state is indeed an S-2 oxidation state with half-integer spin. © Springer Science+Business Media B.V. 2010.