We report the impact of dysprosium (Dy(3+)) dopant and magnesium oxide (MgO) modifier on the thermoluminescent properties of lithium borate (LB) glass via two procedures. The thermoluminescence (TL) glow curves reveal a single prominent peak at 190 °C for 0.5 mol% of Dy(3+). An increase in MgO contents by 10 mol% enhances the TL intensity by a factor of 1.5 times without causing any shift in the maximum temperature. This enhancement is attributed to the occurrence of extra electron traps created via magnesium and the energy transfer to trivalent Dy(3+) ions. Good linearity in the range of 0.01-4 Gy with a linear correlation coefficient of 0.998, fading as low as 21% over a period of 3 months, excellent reproducibility without oven annealing and tissue equivalent effective atomic numbers ~8.71 are achieved. The trap parameters, including geometric factor (μg), activation energy (E) and frequency factor (s) associated with LMB:Dy are also determined. These favorable TL characteristics of prepared glasses may contribute towards the development of Li2O-MgO-B2O3 radiation dosimeters.
Gd2 O2 S:Eu3+ nanophosphors have been successfully synthesized using microwave irradiation and γ-irradiation methods with polyvinyl pyrrolidone as a stabilizer. The physical and luminescence spectra were compared. The morphologies of both Gd2 O2 S:Eu3+ nanophosphors were in the hexagonal phase and mainly consisted of spherical nanostructures with diameters of ~90 nm and ~50 nm for both microwave irradiation and γ-irradiation methods. Upon 325 nm of ultraviolet (UV) light excitation, strong red emissions (626 nm) were observed for both methods; these emissions corresponded to the 5 D0 →7 F2 transition of Eu3+ ions. However, Gd2 O2 S:Eu3+ nanophosphors following microwave treatment showed better luminescence intensity than Gd2 O2 S:Eu3+ nanophosphors treated with γ-irradiation. This difference was attributed to the crystallinity phase and surface quenching effects of Gd2 O2 S:Eu3+ nanophosphors. The reaction mechanisms of Gd2 O2 S:Eu3+ nanophosphors in both methods are discussed in detail.
Lithium borate (LB) glasses doped with dysprosium oxide (Dy2 O3 ) have been prepared by utilizing the conventional melt-quench technique. The prepared glass samples were exposed to 60 Co to check their dosimetric features and kinetic parameters. These features involve glow curves, annealing, fading, reproducibility, minimum detectable dose (MDD), and effective atomic number (Zeff ). Kinetic parameters including the frequency factors and activation energy were also determined using three methods (glow curve analysis, initial rise, and peak shape method) and were thoroughly interpreted. In addition, the incorporation of Dy impurities into LB enhanced the thermoluminescence sensitivity ~170 times. The glow from LB:Dy appeared as a single prominent peak at 190°C. The best annealing proceeding was obtained at 300°C for 30 min. Signal stability was reported for a period of 1 and 3 months with a reduction of 26% and 31%, respectively. The proposed glass samples showed promising dosimeter properties that can be recommended for personal radiation monitoring.
This paper describes the synthesis of poly(1-aminonaphthalene) and its application as a chemosensor for detection of Fe3+ using the naked eye and a fluorimetric method. The conjugated polymer was synthesized by chemical oxidative polymerization using FeCl3 as a catalyst. The response of the polymer towards various metal ions was investigated using colorimetric detection, and ultraviolet-visible and fluorescence spectroscopies. The polymer displayed high selectivity and sensitivity towards Fe3+ compared with other metal ions. A significant colour change from purple to yellow was observed upon addition of Fe3+ by the naked eye. The polymer also showed a high selectivity and sensitivity 'turn-off' fluorescence response towards Fe3+ ions. A good linear response was obtained for Fe3+ concentrations in the range 10-50 mg L-1 with a detection limit of 1.04 mg L-1 . The proposed chemosensor was applied for determination of Fe3+ content in water samples and satisfactory results were obtained.
Carbon-based quantum dots (C-QDs) were synthesized through microwave-assisted carbonization of an aqueous starch suspension mediated by sulphuric and phosphoric acids. The as-prepared C-QDs showed blue, green and yellow luminescence without the addition of any surface-passivating agent. The C-QDs were further analyzed by UV-vis spectroscopy to measure the optical response of the organic compound. The energy gaps revealed narrow sizing of C-QDs in the semiconductor range. The optical refractive index and dielectric constant were investigated. The C-QDs size distribution was characterized. The results suggested an easy route to the large scale production of C-QDs materials.
The penicillin derivative amoxicillin (AMX) plays an important role in treating various types of infections caused by bacteria. However, excessive use of AMX may have negative health effects. Therefore, it is of utmost importance to detect and quantify the AMX in pharmaceutical drugs, biological fluids, and environmental samples with high sensitivity. Therefore, this review article provides valuable and up-to-date information on nanostructured material-based optical and electrochemical sensors to detect AMX in various biological and chemical samples. The role of using different nanostructured materials on the performance of important optical sensors such as colorimetric sensors, fluorescence sensors, surface-enhanced Raman scattering sensors, chemiluminescence/electroluminescence sensors, optical immunosensors, optical fibre-based sensors, and several important electrochemical sensors based on different electrode types have been discussed. Moreover, nanocomposites, polymer, and MXenes-based electrochemical sensors have also been discussed, in which such materials are being used to further enhance the sensitivity of these sensors. Furthermore, nanocomposite-based photo-electrochemical sensors and the market availability of biosensors including AMX have also been discussed briefly. Finally, the conclusion, challenges, and future perspectives of the above-mentioned sensing techniques for AMX detection are presented.
This work explores the thermoluminescence (TL) and photoluminescence (PL) properties of Ag/Y co-doped zinc oxide (ZnO) nanophosphor. The proposed dosimeter was prepared by the coprecipitation method and sintered at temperatures from 400°C to 1000°C in an air atmosphere. Raman spectroscopy was studied to investigate the structural features of this composition. The new proposed dosimeter revealed two peaks at 150°C and 175°C with a small shoulder at high temperature (225°C). The PL spectrum showed strong green emissions between 500 to 550 nm. The Raman spectrum showed many bands related to the interaction between ZnO, silver (Ag), and yttrium oxide (Y2 O3 ). The rising sintering temperature enhanced the TL glow curve intensity. The Ag/Y co-doped ZnO nanophosphor showed an excellent linearity index within a dose from 1 to 4 Gy. The minimum detectable dose (MDD) of the Ag/Y co-doped ZnO nanopowder (pellets) equaled 0.518 mGy. The main TL properties were achieved in this work as follows: thermal fading (37% after 45 days at 1 and 4 Gy), optical fading (53% after 1 h and 68% after 6 h by exposure to sunlight), effective atomic number (27.6), and energy response (flat behavior from 0.1 to 1.3 MeV). Finally, the proposed material shows promising results nominated to be used for radiation measurements.