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Polymeris G.S.,Cultural and Educational Technology Institute CETI | Polymeris G.S.,Isik University | Goudouri O.M.,Aristotle University of Thessaloniki | Paraskevopoulos K.M.,Aristotle University of Thessaloniki | Kitis G.,Aristotle University of Thessaloniki
Key Engineering Materials | Year: 2012

Results of the present study provide strong indications towards the effective application of the 110°C Thermoluminescence (TL) peak in discriminating between different bioactive responses for the case of the 58S bioactive glass. The in vitro bioactivity of this glass in the form of powder in SBF solution was tested for various immersion times, ranging between 0 and 6 days. This TL peak is ubiquitously present in all 58S samples, for all immersion times. The intensity of the 110°C TL peak was proven to be very sensitive to the different bioactive responses, indicating a strongly decreasing pattern with increasing immersion time in SBF, easily identifying thus the loss of silica. This loss is reflected to the decrease of the 110°C TL peak intensity, which appears to be fast even for the shorter immersion times. The 110°C TL glow peak intensity and sensitization could also be yielding a time scale regarding the beginning of some among the several stages included in the bioactivity sequence. © (2012) Trans Tech Publications. Source


Oniya E.O.,Cultural and Educational Technology Institute CETI | Oniya E.O.,Adekunle Ajasin University | Polymeris G.S.,Cultural and Educational Technology Institute CETI | Tsirliganis N.C.,Cultural and Educational Technology Institute CETI | Kitis G.,Aristotle University of Thessaloniki
Radiation Measurements | Year: 2012

Pre-dose sensitization of various components of LM-OSL signal of a Nigerian annealed quartz sample has been investigated along side with that of 110 °C TL peak in this work. Successive cycles of irradiations and TL/OSL readings using different heating rates were employed to attain pre-dose sensitization. The results showed that the pre-dose sensitization factor of 110 °C TL peak depends strongly on the heating rate of thermal activation. The pre-dose sensitization of 110 °C TL and all components of RT LM-OSL yield HR dependence on the sensitization after TA. This dependence was ascribed to the different heating time associated with each HR. Sensitization of LM-OSL measured at 125 °C generally does not show dependence on HR of TA. This was with the exception of components C 1 and C 3. Increasing sensitization pattern with increasing HR suggests a correlation between the TL glow-peak at 110 °C, the component C 4 of RT LM-OSL and the component C 3 of the LM-OSL signal at 125 °C. Extension of the present investigation to diverse quartz kinds from different origins was suggested in order to study the prevalence of the pre-dose sensitization on component C 4 of RT LM-OSL. Finally fast heating is suggested for lower sensitization of fast component while applying OSL dating protocols. © 2012 Elsevier Ltd. All rights reserved. Source


Oniya E.O.,Adekunle Ajasin University | Oniya E.O.,Cultural and Educational Technology Institute CETI | Polymeris G.S.,Cultural and Educational Technology Institute CETI | Tsirliganis N.C.,Cultural and Educational Technology Institute CETI | Kitis G.,Aristotle University of Thessaloniki
Journal of Luminescence | Year: 2012

The fast, linearly modulated optically stimulated luminescence (LM-OSL) component in quartz is the main dosimetric signal used for the dating applications of this material. Since the blue light stimulation (470 nm, 40 mW cm - 2+) time needed to obtain the fast LM-OSL component is less than 50 s the electron trapping levels responsible for it are still highly populated. In this way an active radiation history is created which could play an important role in the dosimetric characteristics of the fast OSL signal. In the present work the dose response behavior of the fast OSL signal is investigated in quartz samples with an annealed radiation history and quartz samples possessing an artificial radiation history. A computerized curve de-convolution analysis of the LM-OSL curves for 50 s stimulation time showed that it consists of three individual OSL components. The faster component C 1 with peak maximum time around 5 s has a linear dose response in virgin samples, which turns to a slight superlinearity as a function of the artificial radiation history. On the other hand the component C 2 with peak maximum time at 12 s is slightly superlinear which turns into strong superlinearity as a function of artificial radiation history. Finally, component C 3 with peak maximum time at about 45 s is strongly superlinear for both virgin samples and as a function of artificial radiation history. The implications to practical application are discussed. © 2012 Elsevier B.V. Source


Polymeris G.S.,Cultural and Educational Technology Institute CETI | Polymeris G.S.,Istanbul Science University | Goudouri O.M.,Aristotle University of Thessaloniki | Kontonasaki E.,Aristotle University of Thessaloniki | And 3 more authors.
Journal of Physics D: Applied Physics | Year: 2011

The formation of a carbonated hydroxyapatite (HCAp) layer on the surface of bioactive materials is the main reaction that takes place upon their immersion in physiological fluids. To date, all techniques used for the identification of this HCAp formation are rather time consuming and not well suited to detailed and rapid monitoring of changes in the bioactivity response of the material. The aim of this work is to explore the possibility of using thermoluminescence (TL) for the discrimination between different bioactive responses in the case of the 58S bioactive glass. Results provided strong indications that the 110 °C TL peak of quartz can be used effectively in the study of the bioactive behaviour of 58S bioactive glass, since it is unambiguously present in all samples and does not require deconvolution analysis. Furthermore, the intensity of the 110 °C TL peak is proven to be very sensitive to the different bioactive responses, identifying the loss of silica which takes place at the first stages of the sequence. The discontinuities of the 110 °C TL peak intensity plot versus immersion time at 8 and 1440 min provide experimental indications regarding the timescale for both the beginning of amorphous CaP formation as well as the end of crystalline hydroxyl-apatite formation respectively, while the spike in the sensitization of the 110 °C TL peak, which was observed for immersion times ranging between 20 and 40 min, could be an experimental feature indicating the beginning of the crystalline HCAp formation. © 2011 IOP Publishing Ltd. Source


Subedi B.,Aristotle University of Thessaloniki | Polymeris G.S.,Istanbul Science University | Polymeris G.S.,Cultural and Educational Technology Institute CETI | Tsirliganis N.C.,Cultural and Educational Technology Institute CETI | And 2 more authors.
Radiation Measurements | Year: 2012

The experimentally measured thermoluminescence (TL) glow curves of quartz samples are influenced by the presence of the thermal quenching effect, which involves a variation of the luminescence efficiency as a function of temperature. The real shape of the thermally unquenched TL glow curves is completely unknown. In the present work an attempt is made to reconstruct these unquenched glow curves from the quenched experimental data, and for two different types of quartz samples. The reconstruction is based on the values of the thermal quenching parameter W (activation energy) and C (a dimensionless constant), which are known from recent experimental work on these two samples. A computerized glow-curve deconvolution (CGCD) analysis was performed twice for both the reconstructed and the experimental TL glow curves. Special attention was paid to check for consistency between the results of these two independent CGCD analyses. The investigation showed that the reconstruction attempt was successful, and it is concluded that the analysis of reconstructed TL glow curves can provide improved values of the kinetic parameters E, s for the glow peaks of quartz. This also leads to a better evaluation of the half-lives of electron trapping levels used for dosimetry and luminescence dating. © 2012 Elsevier Ltd. All rights reserved. Source

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