Investigation of zinc polycarboxylate cement used in dental treatments in terms of retrospective dosimeter.

Zinc polycarboxylate cement is one of the few dental materials that demonstrate true adhesion to tooth structure. It is suitable for use in living organisms without causing harm. Its strong adhesion to teeth and low level of irritancy are two important parameters for the dental applications. In this study, the dosimetry properties of zinc polycarboxylate cement using thermoluminescence (TL) method were investigated and determined the effectiveness of its use as a good dosimeter. According to the results of this study, the sample shows a good TL properties with three main peaks found around 140°C, 220°C and 330°C. It has a wide linear dose response between 72 Gy and 2.3 kGy and good reusability of the TL peak found at 330°C. Unfortunately, the TL peak intensity values are rapidly faded within a short waiting time interval. Zinc polycarboxylate cement, which is frequently used in dental crowns, can be used as a retrospective dosimeter for measuring the amount of radiation in space studies and nuclear accidents due to its wide linear dose-response curve in the high dose region.

Thermoluminescence studies of calcite conducted by bacterial CaCO3 precipitation in organic soil.

In this study, the thermoluminescence (TL) properties of the calcite conducted by bacterial calcium carbonate (CaCO3) precipitation (BCCP) in organic soils were investigated. The bacterial calcium carbonate (CaCO3) precipitation (BCCP) is a popular technique and has been applied in a variety of civil and geotechnical engineering applications. For example, bacterial calcium carbonate precipitation fills the gaps on the organic ground and makes cementing it with the biological method using bacteria. The study reveals that the calcium carbonate mineral called as calcite has a clear TL glow curve with four main peaks located around 90, 140, 210 and 240 °C, a wide linear dose response region between 140Gy and 2.3 kGy is observed. In addition, a good reusability is seen in the high temperature peaks. The TL glow curve peaks are not affected by reusability. Although the dosimetric peaks at 210 and 240 °C appear to be nearly constant, the TL peak intensities at 90 °C and 140 °C completely faded after 24 and 336 h storage time, respectively. The activation energies (Ea) and frequency factors (s) for peaks at 90 °C, 140 °C, 210 °C and 240 °C were evaluated via variable heating rate (VHR). The activation energy of the peaks in the TL glow curve is lying between 0.57eV and 1.04 eV.

Thermoluminescence properties of unique Rosso Levanto marble.

This marble extracted from deposits in Elazig in Turkey resembles red meat in appearance and is only found in Elazig. This type of marble has been widely used in the most famous architectural structures and buildings. In this study, the thermoluminescence (TL) properties of a unique marble that originated from Turkey, named Rosso Levanto, were investigated. Two distinct TL peaks were observed at 160°C and around 375°C. Particle size experiments showed that best TL intensity was seen at 200 µm particle size and therefore dose-response, heating rate, cycle of measurement and fading experiments were carried out on powdered samples with a particle size of 200 µm. The findings revealed good linearity in dose-response, observed up to 0.5 kGy. The reproducibility experiment gave good results, but peak intensity decreased by about 40% in first 6 h of storage in a dark room.

Analysis of thermoluminescence characteristics of a lithium disilicate glass ceramic using a nonlinear autoregressive with exogenous input model.

Dental ceramics because of their translucency exemplify the most biologically realistic restorative materials for aesthetic rehabilitation and can be used to estimate dose accumulated as a result of a nuclear accident or attack. In this study, lithium disilicate ceramic obtained from Vivadent Ivoclar, Turkey was studied for its thermoluminescence (TL) properties. The lithium disilicate glass ceramic was irradiated with a 90 Sr-90 Y ß-source from 10 Gy to 6.9 kGy and the results read on a Harshaw 3500 reader. The TL peak of lithium disilicate ceramic showed sublinearity in the range 12 Gy to 6 kGy. The area under the TL glow curve increased by about 25% by the end of 10th measurement cycle. Fading values were also considered after irradiation. Lithium disilicate ceramic samples underwent 37% fading after 1 h and 59% fading after 1 week. In addition to the experimental study, a software-based simulation study was also undertaken using a MATLAB system identification tool. Experimental studies are generally time consuming and some materials used for experiments are very expensive. In this study, experimental, and simulation results were compared and produced almost the same outcome with a similarity of more than 98%.

Thermoluminescence dosimetric properties of silicon carbide (SiC) used in industrial applications.

Silicon Carbide (SiC), also known as carborundum, has been found to be widely useful as a substrate and wide band gap semiconductor in radiation resistant optoelectronic devices. The aim of this study is to discuss the thermoluminescence (TL) properties of silicon carbide (SiC) used in industrial applications for dosimetric purposes. Basic TL properties of these materials such as dose response, heating rate, fading effect and reproducibility have also been investigated. The largest TL peak intensity was observed at 400-1000 µm of particle size for the dosimetric peak (≈250 °C). A wide linear region between 12Gy and 2.3 kGy was observed. The good reproducibility was obtained with small standard deviation but low-temperature peaks were completely faded after 30 min storage in a dark room.

TLD characteristic of glass, feldspathic and lithium disilicate ceramics.

Thermoluminescence (TL) emission of dental ceramics could be potentially used for retrospective dosimetry purposes as this allows a quick and reliable dose assessment in case of nuclear accident or bad use of a nuclear attack. This paper reports on the chemical and luminescence characterization of glass, feldspathic and lithium disilicate glass ceramic (LS2 ). Swedish and Turkish dental ceramics supplied by Vivadent Ivoclar considering: (i) the dose response in the range 10 Gy to 6.9 kGy which displays a linear dose-response at low dose values up to 36 Gy (glass and feldspathic ceramics) and shows sublinear behavior from 12 Gy to 6 kGy (lithium disilicate glass ceramics), (ii) a reproducibility of the TL signal in which the area under the glow curve increased about 25% after 10 cycles for glass and lithium disilicate ceramics and increased about 30% after seven cycles for feldspathic ceramics, (iii) stability of the luminescence emission with the elapsed time and (iv) effect of the heating rate. Glass, lithium disilicate and feldspathic ceramics display a complex UV-blue glow emission that can be respectively fitted to five and four groups of components assuming first-order kinetics behavior.

Thermoluminescence behavior of basaltic rocks collected in southeastern region of Turkey.

Basalt is well known as an extrusive igneous rock erupts on land by volcanic eruption. It is darker, denser and finer grained compared to the familiar granite of the continents. The study reveals the thermoluminescence properties (TL) of basaltic rocks which collected in southeastern region of Turkey. With this study, the variations of glow curve of the basalt at the different grain sizes, different annealing temperature and different annealing time have been investigated. This study also includes, dose response and heating rate experiments. As a result, the basalt sample shows thermoluminescence properties with a wide peak about 200°C. The best TL sensitivity was observed at samples whose grain size is ~100µm. The basalt sample has a wide TL glow curve. A linearity for the values up to 155Gy and supralinearity between 155Gy and 615Gy in dose response are observed and it reaches to saturation beyond 615Gy. Thermal treatments at higher temperatures decrease the TL sensitivity.

Thermoluminescence glow curve analysis of natural onyx from Turkey.

In this study, the thermoluminesce (TL) properties of natural onyx were determined after ß-irradiation ((90)Sr/(90)Y) at room temperature. The effect of the additive dose and variable heating rate for TL glow peaks of the sample were investigated. Computerized glow curve deconvolution (CGCD) methods were used to determine the number of peaks and kinetic parameters related to the TL glow peaks in natural onyx from Turkey. It was also determined kinetic parameters of onyx by means of the variable heating rate (VHR) method. The sample was exposed to ß-irradiation between 2.4 Gy and 2.457 kGy. The CGCD methods showed that the glow curve of sample is the superposition of at least six first order components which were ascribed as P1-P6. The dose responses of some peaks have similar patterns and they follow linearity. The effect of heating rates on the response of dosimetric glow peaks of sample was studied. The maximum TL peak intensities of glow curve are decreasing with increasing heating rate and maximum TL peak intensities at 1 °C/s drops to 20% of the initial value when the sample is read at 6 °C/s.