Novel Tb³âº-Doped LaAl2B4O10 phosphors: Structural analysis, luminescent properties, and energy transfer mechanism.

This study explores the structural and luminescent properties of terbium (Tb³âº)-doped lanthanum aluminium borate (LaAl2B4O10, abbreviated as LAB) phosphors, a novel host lattice for Tb³âº doping. LAB:Tb³âº phosphors, with varying dopant concentrations, were synthesized using a microwave-assisted combustion synthesis approach and characterized using X-ray diffraction (XRD), Rietveld refinement, and photoluminescence spectroscopy at both room and low temperatures. The structural analysis confirmed the hexagonal crystal structure of LAB and revealed successful incorporation of Tb³âº ions without altering the fundamental lattice. Luminescence studies demonstrated that the LAB:Tb³âº phosphors show strong green emission primarily attributed to the 5D4→7F5 transition of Tb³âº. The optimal doping concentration was determined to be 5 wt% Tb³âº, which provided maximum luminescence efficiency. This concentration also allowed for a critical study of energy transfer mechanisms within the phosphor, revealing dipole-dipole interactions with a critical distance of 9.80 Å between Tb³âº ions. Additionally, the CIE chromaticity coordinates of LAB:0.05 Tb³âº were precisely determined to be (0.289, 0.4460), indicating the potential for high-quality green emission suitable for solid-state lighting and display technologies. This work not only demonstrates the potential of LAB:Tb3+ as a highly efficient green luminescent material, but also sheds light on the mechanisms responsible for energy transfer and concentration quenching.

Beta irradiation-induced thermoluminescence: Glow curve analysis and kinetic parameters in combustion-synthesized undoped Ca4YO(BO3)3.

This study examines the thermoluminescent (TL) properties of undoped Ca4YO(BO3)3 phosphor, focusing on how it behaves under a variety of experimental conditions. The IRSL-TL 565 nm was chosen as the appropriate detection filter among various optical detection filter combinations. During the preheating trials conducted at a rate of 2 °C/s, the TL peak exhibited increased intensity, particularly around 200 °C. The experimental outcomes demonstrated a reliable linear relationship (R2 = 0.996 and b = 1.015) in the dose response of undoped preheated Ca4YO(BO3)3 within the range of 1-200 Gy. The investigation encompasses a range of techniques, including the TM-Tstop method, computerized glow curve deconvolution (CGCD) analysis, and theoretical modelling. The application of the TM-Tstop method to samples irradiated with a 5 Gy dose revealed distinct zones on the TM versus Tstop diagram, signifying the presence of at least two discernible components within the TL glow curve, specifically, a single general order kinetics peak and a continuous distribution. The analysis of activation energy versus preheated temperature exhibited a stepwise curve, indicating five trap levels with depths ranging between 1.13 eV and 1.40 eV. The CGCD method also revealed the superposition of at least five distinct TL glow peaks. It was observed that their activation energies were consistent with the Tm-Tstop experiment. Furthermore, the low Figure of Merit (FOM) value of 1.18% indicates high reliability in the goodness-of-fit measure. These findings affirm the reliability and effectiveness of the employed methods in characterizing the TL properties of the Ca4YO(BO3)3 phosphor under investigation. Theoretical models, including the semi-localized transition model, were introduced to explain anomalous observations in TL glow peak intensities and heating rate patterns. While providing a conceptual framework, these models may require adjustments to accurately capture the specific characteristics uncovered through CGCD analysis. As a potential application, the study suggests that the characterized TL properties of Ca4YO(BO3)3 phosphor could be utilized in dosimetric applications, such as radiation dose measurements, owing to its reliable linear response within a broad dose range.

Temperature-dependent photoluminescence of novel Eu3+, Tb3+, and Dy3+ doped LaCa4O(BO3)3: Insights at low and room temperatures.

This study explores the structural and optical qualities of LaCa4O(BO3)3 (LACOB) phosphors doped with Eu3+, Dy3+, and Tb3+ using a microwave-assisted sol-gel technique. It uncovers oxygen-related luminescence defects in LACOB, highlighting emission peaks at 489 and 585 nm for Dy3+, a distinct sharp peak at 611 nm for Eu3+ in the red spectrum, and a notable green emission for Tb3+ due to specific transitions. The photoluminescence (PL) analysis indicates that luminescence is optimized through precise doping, leveraging dipole interactions, and localized resonant energy transfer, which are influenced by dopant concentration and spatial configuration. Temperature studies show emission intensity variations, particularly noticeable below 100 K for Tb3+ doped samples, demonstrating the nuanced balance between thermal quenching and luminescence efficiency. This temperature dependency, alongside the identified optimal doping conditions, underscores the potential of these materials for advanced photonic applications, offering insights into their thermal behavior and emission mechanisms under different conditions.

Temperature-responsive insights: Investigating Eu3+ and Dy3+ activated yttrium calcium oxyborate phosphors for structure and luminescence.

An investigation into the luminescent behavior of YCOB (Yttrium Calcium Oxyborate) doped with Eu3+ and Dy3+ ions, synthesized via the combustion method, is presented. The study, employing X-ray diffraction (XRD), Fourier-Transform Infrared Spectroscopy (FTIR), and Energy-Dispersive X-ray Spectroscopy (EDS) analyses, confirms the structural integrity and purity of the synthesized nanophosphors. An XRD pattern exhibiting distinct crystalline peaks indicates that the dopant ions were successfully integrated into the YCOB lattice. The photoluminescence (PL) response of YCOB with Eu3+ and Dy3+ ions is thoroughly examined, uncovering distinct excitation and emission spectra. In the case of Eu3+ doping, excitation spectra reveal a significant charge transfer (CT) band at 254 nm, indicative of electron transfer between oxygen and europium ions. This CT transition enhances our understanding of the excitation behavior, with the dominant and Laporte-forbidden 5D0 → 7F2 transition. Characteristic peaks at 345 nm in the excitation spectra efficiently stimulate YCOB:Dy3+ when Dy3+ is used as a dopant. The primary emission peak at 585 nm corresponds to the hypersensitive electric dipole transition 4F9/2-6H13/2. Concentration quenching phenomena are observed, with a maximum Eu3+ concentration of 7 wt % attributed to the dipole-quadrupole interaction. Dy3+ doping, with a maximum concentration of 2 wt % primarily shows multipolar interactions, especially dipole-dipole interactions. The study extends to CIE chromaticity analysis, emphasizing Eu3+ doping's suitability for white light-emitting diode (WLED) applications and ensuring color stability. Conversely, varying Dy3+ concentrations do not yield consistent chromaticity coordinates. These findings have significant implications for the development of advanced phosphor materials across diverse applications, offering a roadmap for optimizing their optical performance.

Europium-doped strontium gadolinium oxide phosphor: Investigating structural and photoluminescence characteristics via sol-gel combustion synthesis.

SrGd2O4 phosphors doped with Eu3+ were successfully synthesized through a sol-gel combustion method, covering a range of dopant concentrations from 0.25 mol% to 3 mol%. The structural analysis of these phosphor materials was comprehensively conducted utilizing various techniques, including X-ray powder diffraction analysis (XRD), Energy Dispersive X-ray (EDX), and Fourier-transform infrared spectroscopy (FTIR). In addition to unveiling the structural characteristics, these analyses provide valuable insights into the compositional aspects, enhancing our understanding of the synthesized SrGd2O4:Eu3+ phosphors across different doping levels. XRD analysis findings validate the successful generation of the intended SrGd2O4 host, demonstrating orthorhombic system structures consistent with JPCD card number 98-019-3592. FTIR analyses conducted on the phosphor samples not only identify bending modes but also reveal intricate details about small vibration bonds within the material. When excited by the 349 nm laser, SrGd2O4:xEu3+ phosphors exhibit distinct photoluminescence (PL) properties like red emission at 614 nm from Eu3+. From the emission spectra, one can clearly observe that Eu3+ with an ionic radius close to the Gd3+ ion preferentially occupies the symmetry sites of the host lattice. The optimal doping concentration was determined to be 0.5 mol%, as revealed by the data in our study. Additionally, a deeper understanding of the luminescence quenching mechanism was attained, pinpointing the involvement of dipole-dipole (d-d) energy transfer in this intriguing phenomenon. This optimal concentration not only enhances the material's properties but also underscores the pivotal role of d-d interactions in governing the luminescence behavior within the doped system.

Luminescence of undoped and Eu3+ activated zinc gallate phosphor: Synthesis, unusual intense 5D0 → 7F4 red emission.

A series of Eu3+-doped ZnGa2O4 samples were synthesized via the urea-glycine combustion route. Powder X-ray diffraction (XRD) was used to investigate the crystallinity of the samples, energy dispersive spectroscopy (EDS) to explore the elemental composition, Fourier transform infrared (FTIR), to observe the vibrational modes of the samples, photoluminescence (PL) to determine the luminescence properties. The XRD data prove that the samples remain single cubic structure even at high concentrations of Eu³âº, enabling the formation of a unique emission spectrum. The active ion concentration was varied to examine the influence of concentration on luminescent properties. This study revealed a 5D0 →7F4 transition located at 700 nm with unusual intensity that has not been documented in the literature, which suggests that the active ion concentration can influence the luminescent characteristics of the phosphors. The increasing Eu3+ content increases the number of Eu3+ ions in ZnGa2O4 host lattice, which enhances the luminescence efficiency of the phosphor. However, beyond a certain level of Eu3+content (i.e., 3 wt% Eu3+), the number of Eu3+ ions becomes excessive, resulting in a reduction in luminescence efficiency due to concentration quenching. The dipole dipole interaction is elucidated to play a prominent role in the mechanism of Eu3+ quenching in the ZnGa2O4. An assessment of color coordinates based on emission spectra reveals that the coordinates shift from blue to the white light region, and then to red as Eu3+ content increases. This suggests that there is a substantial relationship between the Eu3+ concentration and the measured color coordinates.

Thermoluminescence in GdAl3(BO3)4 phosphors: Unusual heating rate dependencies, dose responses and kinetic parameters.

The current study focuses on the production of GdAl3(BO3)4 (GAB) phosphors using gel combustion. X-ray diffraction (XRD) and thermoluminescent (TL) methods were used to investigate the structural and thermoluminescence (TL) features of the samples. XRD results revealed that GAB phosphors were crystallized in a rhombohedral crystal system. TL experimental data exhibited an unusual heating rate behaviour, which was explained by the semi-localized transition model, and this provides valuable insight into the properties of the GAB sample. Beta-irradiated GAB hosts exhibit two primary peaks at 106 °C and 277 °C on their TL glow curves. We have employed a variety of heating rates (VHRs), TM-Tstop method, and computerized glow curve deconvolution (CGCD) techniques. By using a combination of these techniques, we can identify the kinetic parameters of the GAB samples more accurately, including peak numbers, activation energy, and frequency factors. Both Tm-Tstop and CGCD techniques produce similar results in terms of trap numbers and trap depths. In the trap centers, electrons were trapped at 1.05 eV, 0.84 eV, 1.12 eV, 1.20 eV, 1.42 eV, 1.63 eV and 1.42 eV. There was a linear behaviour of GAB samples over a dose range of 0.1 Gy-10 Gy. GAB phosphors did not show any significant changes in TL response with repeated irradiation cycles, suggesting that it is a reliable radiation dosimeter. GAB is therefore a potential candidate for radiotherapy dose measurement based on these findings.

Anomalous dose behaviour of thermoluminescence glow curves and kinetic analysis of beta irradiated YAl3(BO3)4:Tb phosphor.

With the aid of thermoluminescence (TL), we have extensively studied YAl3(BO3)4 host matrices incorporated with Tb3+ at different doping contents, which have been produced by combustion. The measured the TL glow curves exposed to beta rays at different doses consisted of four broad peaks located at around 76, 126, 230, and 378 °C. The peak maximum of the 230 °C TL peak shifts toward higher temperatures after 5 Gy beta irradiation while the other peak maxima almost remain constant. It is peculiar that 230 °C peak maximum shifts to higher temperatures with increased radiation dose and can be attributed to the multiple phases of the sample. A TL glow curve exhibits a proportional increase in intensity with increased the heating rate. A discussion of the possible causes of this pattern is provided. Observed peaks using the Tm─Tstop method are due to the presence of a quasi-continuous distribution of traps. The parameters of the traps have also been estimated using various heating rate methods in excellent agreement with one another.

Adsorption of thorium (IV) ions using a novel borate-based nano material Ca3Y2B4O12: Application of response surface methodology and Artificial Neural Network.

Since nuclear wastes are the most important wastes in terms of health and the environment, they are evaluated differently within nuclear reactors as well as in terms of their use in medical and industrial applications. In some cases, emergency intervention is necessary due to the amount of radioactivity or the physical and/or chemical conditions. . The purpose of this study is to investigate the adsorption properties of nano Ca3Y2B4O12 (CYBO) material synthesized by the sol-gel combustion method for the adsorption of Thorium (IV) from an aqueous medium. We tested how pH (3-8), the concentration of Th (IV) (25-125 mg/L), amount of adsorbent value (0.005-0.08 g) and temperature (20-60 °C), affect adsorption efficiency. The best possible combinations of these parameters were examined by Response Surface Methodology (RSM) and Artificial Neural Network (ANN). R2 values for RSM and ANN were 0.9964 and 0.9666, respectively. According to the models, the adsorption capacity under the optimum conditions determined for the RSM and ANN model was found to be 134.62 mg/g and 125.12 mg/g, respectively.

Thermoluminescence characteristics and kinetic analyses of europium doped strontium gadolinium oxide phosphor.

In this work, SrGd2O4 phosphors incorporated with Eu3+ at various dopant concentrations are synthesized via solid state reaction method. An X-ray diffraction (XRD) and thermoluminescence (TL) technique were used to examine the structural and thermoluminescent properties of as-prepared phosphors. Orthorhombic phase formation of Eu3+ doped samples was confirmed by XRD. The influence of impurity concentration and heating rates on the glow curves was also investigated. Anomalous heating rate pattern was observed in the sample with Eu3+ additive. A model of semi-localized transition was used to explain this behaviour. The TL glow curves of beta irradiated SrGd2O4:Eu3+ (0.25 mass %) reveal three well-resolved peaks at 105, 189, and 245 °C. Various heating rates, TM-Tstop, initial rise, and computerized glow curve deconvolution techniques were employed to detect the overlapping peak numbers and establish the kinetic parameters of SrGd2O4:Eu3+ (0.25 mass %). When the trap numbers and comparable energy values are considered, the findings of the approaches are very similar. For the dose ranges between 0.1 and 8 Gy, SrGd2O4:Eu3+ (0.25 mass %) samples exhibited linear behaviour, and high reproducibility, indicating their applicability for TL dosimetry applications.

Is thyroid-stimulating hormone a predictor of severity of carotid artery disease?

OBJECTIVE: The relationship between thyroid function and carotid artery stenosis in euthyroid patients is controversial. Therefore, we aimed at evaluating the relationship between the severity of carotid artery disease (CAD) and thyroid-stimulating hormone (TSH) levels in euthyroid patients. PATIENTS AND METHODS: A total of 90 euthyroid patients with CAD were trichotomized into three groups based on CAD severity. Group 1 comprised patients who had one internal carotid artery with total stenosis and the other with more than 50% stenosis. In Group 2, patients had one internal carotid artery with total stenosis and the other with less than 50% stenosis. Group 3 comprised patients with less than 50% stenosis in both internal carotid arteries. Demographic data, complete blood count, biochemical parameters, and thyroid function parameters were compared between the groups. RESULTS: No significant relationship was noted between the severity of CAD and demographic data and comorbidity rates. A comparison of the biochemical parameters revealed that TSH levels were significantly different between the groups. Post-hoc analysis showed that Group 1 and Group 3 differed significantly with respect to TSH levels (0.75 ± 0.37 IU/mL vs. 1.39 ± 1.00 IU/mL, p=0.002). A cut-off value of 0.65 yielded 46.67% sensitivity and 81.67% specificity, whereas a cut-off value of 0.70 yielded 53.33% sensitivity and 75.00% specificity. The area under the curve was 0.691 (95% CI, 0.576-0.806) (p=0.003). CONCLUSIONS: TSH can be demonstrated to predict severe carotid artery disease. Therefore, the severity of CAD can be assessed using TSH levels.

Thermoluminescence glow curve analysis of Ca3Y2B4O12 phosphor prepared using combustion method.

Ca3Y2B4O12 (CBYO) phosphor was synthesized using a gel combustion method. X-ray diffraction (XRD) measurement confirmed a single-phase structure (space group Pnma (62)) of synthesized compound. TL measurements were conducted between room temperature (RT) and 450 °C at a heating rate of 2 °Cs-1. Significant glow peaks were observed at 64, 116, and 242 °C in CYBO phosphor sample exposed to different beta doses. In the range of 0.1-100 Gy, the TL intensity of the glow peak displayed good linearity. Different methods were employed to determine the number of peaks, the trap structure, and the kinetic parameters of the thermoluminescence glow curve of CBYO; the Hoogenstraaten method, various heating rates (VHR), and glow curve deconvolution method (CGCD) implemented through tgcd:An R package. Currently available findings confirm that CYBO host is a promising candidate for environmental studies because one exhibits adequate TL dose response coupled with a good sensitivity and linearity.

Novel Dy incorporated Ca3Y2B4O12 phosphor: Insights into the structure, broadband emission, photoluminescence and cathodoluminescence characteristics.

This study reports cathodoluminescence (CL) and photoluminescence (PL) properties of undoped borate Ca3Y2B4O12 and Ca3Y2B4O12:x Dy3+ (x = 0.5, 1, 2, 3, 5, and 7) synthesized by gel combustion method. Micro-X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), CL and PL under electron beam and 359 nm pulse laser excitation, respectively were used to investigate characterization and luminescence studies of synthesized samples in the visible wavelength. As-prepared samples match the standard Ca3Y2BO4 phase that belongs to the orthorhombic system with space group Pnma (62) based on XRD results. Under electron beam excitation, this borate host shows a broad band emission from about 250 to 450 nm, peaked at 370 nm which is attributed to NBHOC. All as-prepared phosphors exhibited the characteristic PL and CL emissions of Dy3+ ions corresponding to 4F9/2→6HJ transitions when excited with laser at 359 nm. The CL emission spectra of phosphors were identical to those of the PL spectra. Concentration quenching occurred when the doping concentration was 1 mol% in both the CL and PL spectra. The underlying reason for the concentration quenching phenomena observed in the discrete orange-yellow emission peaked at 574 nm of Dy3+ ion-doped Ca3Y2B4O12 phosphor is also discussed. According to these data, we can infer that this new borate can be used as a yellow emitting phosphor in solid-state illumination.

How childhood trauma and emotions influence essential tremor and its severity in Sakarya Province.

OBJECTIVE: Essential tremor (ET) is among the most common central nervous system disorders. It is characterised by symmetrical and bilateral postural tremor, usually affecting the hands. Alongside such motor symptoms, psychiatric symptoms, such as anxiety and depression, often occur. This study aimed to investigate how anxiety, depression and childhood trauma influence ET patients' tremor frequency and severity. PATIENTS AND METHODS: The participants comprised 85 patients and 70 control volunteers. Participating patients have been admitted to our clinic for hand tremor complaints and diagnosed with ET, according to the Washington Heights Inwood Genetic Study of Essential Tremor (WHIGET) diagnosis criteria, and they returned for follow-up for at least one year after their initial treatment. Patients with thyroid dysfunction, Parkinson's disease, central nervous system pathology, a history of smoking or alcohol use or a history of drug use that may cause tremor were excluded from the study. Patients' demographic data, such as their age and gender, age at disease onset, disease duration, family history and tremor severity were recorded. The Beck Anxiety Inventory (BAI), Beck Depression Inventory (BDI) and Childhood Trauma Questionnaire (CTQ) were applied to all patients. RESULTS: Statistically significant differences were found in BDI score averages and BAI score averages between the patient and control groups (p = 0.002; p = 0.001) and physical abuse, emotional neglect and sexual abuse scores on the CTQ scale (p = 0.001, p = 0.007 and p = 0.001, respectively). CONCLUSIONS: Childhood mental trauma and emotional mood disorders are more common among ET patients. However, these disorders do not appear to affect ET severity.

Specialist physicians battle against the COVID-19 pandemic: the relationship between specialist physicians working conditions and levels of burnout during the COVID-19 pandemic.

OBJECTIVE: This study was planned to determine the burnout levels of physicians during the COVID-19 pandemic, and to contribute to taking the necessary measures by determining the associated factors. MATERIALS AND METHODS: This research was designed via Google Online Form as an online survey with questions of Sociodemographic Data Form, Maslach Burnout Inventory and Beck Anxiety Inventory and was conducted with 40 specialist physicians actively working at the Sakarya University Training and Research Hospital. The same questionnaire was re-applied online after two months, and 24 out of 40 physicians were accessed. The SPSS 25 (IBM, Armonk, NY, USA) program was used for the analysis of the data. RESULTS: According to the Maslach Burnout Inventory applied in the pre-test, it was found that the feeling of personal accomplishment was high, emotional burnout was normal, and depersonalization was low. Anxiety and burnout were found to be positively correlated, and there were no statistically significant differences in the average values of the pre-and post-test Maslach Burnout Inventory and Beck Anxiety Inventory scores. CONCLUSIONS: Detecting possible burnout in physicians working in a pandemic, identifying associated factors and taking required measures can be beneficial both for physicians and society from a biopsychosocial perspective.

Synthesis and beta particle excited thermoluminescence of BaSiF6 phosphor.

BaSiF6 phosphor was synthesized by a gel combustion method. The crystalline size was found to be 54.17 ± 4.36 nm using Williamson-Hall (W-H) approximation. The TL data collected by means of a combination of a commercial BG39 and HC575/25 filters was studied to evaluate basic kinetic parameters. Three TL glow peaks of BaSiF6 phosphors are centered at around 84, 190 and 322 °C. Tm-Tstop, various heating rate (VHR) and computerized glow-curve deconvolution (CGCD) method were utilized to analyse collected data. Our findings indicate that luminescence process in scrutinized material may obey second order kinetics. The TL dose response of the TL glow peaks exhibits a linear characteristic up to 100 Gy. Deconvolution of the glow curve reveals that the number of the component TL glow peaks in the complex glow curve is composed of well-isolated six overlapping glow peaks. The FOM value is 2.32.

Adsorption of thorium (IV) ions by metal ion doped ZnO nanomaterial prepared with combustion synthesis: Empirical modelling and process optimization by response surface methodology (RSM).

Environmental problems have reached enormous dimensions, driving efforts to remove and recycle waste from energy and industrial production. In particular, removing the radionuclide contamination that occurs as the nuclear industry grows is difficult and costly, but it is vital. Technologic and economical methods and advanced facilities are needed for the separation and purification of radioactive elements arising from the nuclear industry and uranium and thorium mining. With the adsorption method, which is the most basic separation and recovery method, the use of high-capacity nanomaterials has recently gained great importance in reducing the activity of the waste, reducing its volume by transforming it into solid form, and recovering and removing liquid radioactive wastes that might harm the ecological environment. This study aimed to determine the adsorption properties of metal ion-doped nano ZnO (nano-ZnO:Al) material synthesized by the microwave-assisted gel combustion method for the adsorption of thorium (IV) from aqueous media. First, characterization processes such as XRD, SEM, BET and zeta potential were performed to observe changes in the host ZnO adsorbent structure caused by the doping process. Later, this was optimized via the response surface method (RSM), which is widely used in the characterization of the adsorption properties of thorium (IV) from aqueous solutions. Such characterization is commonly used in industrial research. We tested how pH (3-8), temperature (20-60 °C), Th (IV) concentration (25-125 mg/L) and adsorbent amount (0.01-0.1 g) affect adsorption efficiency. The best possible combinations of these parameters were determined by RSM. It was calculated by RSM that the design fits the second order (quadratic) model using the central composite design (CCD) for the design of experimental conditions. R2 and R2 adjusted values from the parameters showing the model fit were 0.9923 and 0.9856, respectively. According to the model, the experimental adsorption capacity was 192.3 mg/g for the doped-ZnO nanomaterial under the theoretically specified optimum conditions. Also, the suitability of Th (IV) adsorption to isotherms was examined and thermodynamic parameters were calculated.

Synthesis and photoluminescence characteristics of a novel Eu and Tb doped Li2MoO4 phosphor.

Li2MoO4:x Eu3+ and Li2MoO4:xTb3+ phosphors, where x = 0.5, 1, 2, 3, 5 and 7 wt%, were synthesized through a gel-combustion method. The XRD data reveals that Eu3+ and Tb3+ doped Li2MoO4 phosphors exhibit a Rhombohedral structure belonging to the space group R3 which matched well with the standard JCPDS files (No.012-0763). We present photoluminescence (PL) spectra from Eu and Tb doped Li2MoO4 under 349 nm Nd:YLF pulses laser excitation over the temperature range of 10-300 K. Undoped Li2MoO4 shows a wide broad band around 600 nm because of the intrinsic PL emission of tetrahedral of MoO42- which was in good agreement with previous findings. Under the excitation of 394 nm, the as-synthesized phosphors exhibited sharp and strong intensity PL emission signals in the red (612 nm, 5D0→7F2 transition) and green (544 nm, 5D4→7F5 transition), respectively. The critical doping concentration of Eu3+ and Tb3+ ions in the Li2MoO4 were estimated to be 2 wt%. The concentration quenching phenomena were discussed, and the critical distances for energy transfer have also been evaluated by the concentration quenching.

Characterization of thermoluminescence kinetic parameters of beta irradiated B doped Ca5(PO4)3OH powder obtained from eggshell.

In this study, we have synthesized B doped Ca5(PO4)3OH (HAP) by a sonication chemical method. The thermoluminescence (TL) properties of the family of synthesized samples (B doped Ca5(PO4)3OH (HAP) were investigated using an IRSL-TL 565 nm filter. This gave the highest TL intensity of each phosphor after 2 Gy ß-irradiation. Three TL glow peaks of B doped Ca5(PO4)3OH (HAP) are centered at around 84, 208 and 324 °C (with a heating rate of 2 °Cs-1). The trapping parameters such as activation energy (E), order of kinetics (b), frequency factor (s) were calculated by using initial rise (IR), various heating rates (VHR) and computerized glow curve deconvolution (CGCD) method. The response of TL glow curves remained constant within ±5% deviation from the initial value after 9 cycles of reuse; but only at tenth cycle the deviation goes up to 6%.

SURVIVIN POSITIVITY AND PROGNOSTIC FACTORS IN PAPILLARY THYROID CARCINOMAS.

Context: Papillary thyroid carcinoma(PTC)s are the indolent progressive tumours. Survivin is a unique bifunctional protein with cell cycle regulation and apoptosis inhibition. The expression of this protein has been shown to be increased in thyroid tumours correlated with aggressive behavior from well differentiated to anaplastic. Objective: In this study, we aimed to investigate the relationship between immunohistochemically survivin expression and tumour-associated prognostic factors in papillary thyroid carcinomas. Design: In patients with thyroidectomy, we compared the clinicopathological findings and immunohistochemical positivity for survivin. Subjects and Methods: In 109 patients, sex, age, tumour size, histological tumour variant, tumour focality, tumour border pattern, tumour peripheral/intratumoural lymphocytic and stromal response, intraglandular spread, extrathyroideal spread, lymph node metastases, lymphocytic tiroiditis and relationships of these findings with survivin positivity were investigated. Results: When we indicated the tumour size and compared it with survivin expression, tumour size correlates with, survivin expression (p = 0.016). Survivin expression was correlated statistically significant with lymphovascular invasion, without stromal response and with intraglandular extension respectively (p<0.001, p = 0.043, p<0.001). No significant correlation was found between other clinicopathological parameters and survival. Conclusion: Few studies have investigated the relationship of survivin expression with prognosis in thyroid papillary carcinomas and showed that survivin was a poor prognostic marker. If its expression is detected in preoperative cytology smears, it may affects the surgical treatment strategy. When it is detected in the tissue, postoperative radioactive iodine treatment plan may be modified and the need for more aggressive follow-up may be considered.