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In this study, a glass system based on heavy metal oxides, namely Pb 3 O 4 -Sb 2 O 3 -SiO 2 , was prepared with Ho 2 O 3 , Er 2 O 3 , and Tm 2 O 3 as dopants. The prepared glass were characterized using X-ray diffraction (XRD) and infrared (IR) studies. The luminescence efficiencies of the three rare earth ions viz., Ho 3+ , Er 3+ , and Tm 3+ in the glass system were investigated, specifically focusing on green (Ho 3+ , Er 3+ ), blue (Tm 3+ ), and near-infrared (NIR) emissions. The optical absorption (OA) and photoluminescence (PL) spectra of RE mixed glass displayed strong bands in the visible and NIR regions, which were analyzed using the Judd-Ofelt (J-O) theory. The J-O coefficients (Ω λ ) were found to be in the order of Ω 2  > Ω 4  > Ω 6 for all the three glass. Notably, the Tm 3+ -doped glass exhibited the lowest Ω 2 value, which was attributed to a larger degree of disorder in the glass network due to lower fractions of Sb 5+ and Pb 4+ ions that take part in the glass network forming. This conclusion was arrived based on the IR studies. Furthermore, the quantitative analysis of PL spectra and decay curves indicated that SbHo and SbEr glass were suitable for efficient green emission, while SbTm glass is a promising choice for blue laser emission., (© 2023 John Wiley & Sons Ltd.)

Li 2 O-HfO 2 -SiO 2 -Tm 2 O 3 :Au 2 O 3 glass samples (containing fixed content of Tm 2 O 3 and different concentration of Au 2 O 3 ) were prepared and characterized. Bearing of Au 0 metallic particles (MPs) on improving blue emission of thulium ions (Tm 3+ ) ions was explored. Optical absorption (OA) spectra exhibited multiple bands excited from 3 H 6 of Tm 3+ . Additionally, a broad peak in the wavelength range 500-600 nm due to surface plasmon resonance (SPR) of Au 0 MPs was noticed in the spectra. Photoluminescence (PL) spectra (of thulium free glasses) indicated a peak in the visible range due to sp → d electronic transition of Au 0 MPs. Luminescence spectra of Tm 3+ and Au 2 O 3 co-doped glasses exhibited intense blue emission with substantial increase of intensity with increase of Au 2 O 3 content. Bearing of Au 0 MPs on the reinforcement of blue emission of Tm 3+ was discussed in detail with kinetic rate equations., (© 2023 John Wiley & Sons Ltd.)

Introduction  Vaccination has shown to be protective against severe coronavirus disease 2019 by various studies. However, the vaccine efficacy was demonstrated to be less against the emerging variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Both vaccine- and infection-induced immunity against SARS-CoV-2 may prevent reinfection and severity. Our study aims to assess and compare the humoral response in heterogeneous population based on infection and vaccination status along with hybrid immunity. Methods  A retrospective, observational study of 2,545 adults was conducted. The study groups comprised of group I ( n  = 309) naive with a single dose of vaccination, group II ( n  = 357) infected and unvaccinated, group III ( n  = 590) completely vaccinated with two doses of vaccine, group IV ( n  = 70) booster dose, group V ( n  = 602) with hybrid immunity (pre-vaccination infection), and group VI ( n  = 617) with breakthrough infection (post-vaccination infection). Data pertaining to demographic details, clinical presentations, reverse transcription-polymerase chain reaction, anti-SARS-CoV-2 total antibodies immunoglobulin G (IgG), neutralizing antibodies by anti SARS-CoV-2 sVNT (surrogate virus neutralization test), S1/S2IgG, S-RBD (receptor-binding domain), and ChAdOx1-nCov-19 (Covishield) vaccination were retrieved from electronic health records. Results  The mean levels of neutralizing antibodies of group V were S1/S2, RBD (10.5/14.3 times), and sVNT (84.44%) and group VI had S1/S2, RBD (11.4/11.8 times), and sVNT (78.07%) when compared to group III. We also observed a statistically significant higher immune response in group V and VI than group I and II. A higher percentage (18.2%) of group II individuals had severe disease when compared to group V and VI (6.5/10.8%). Conclusion  A single dose of ChAdOx1 vaccine gives robust antibody responses in previously infected individuals and may confer long-term hybrid immunity following booster vaccination., Competing Interests: Conflict of Interest None declared., (The Indian Association of Laboratory Physicians. This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. ( https://creativecommons.org/licenses/by-nc-nd/4.0/ ).)

This study consists of the results of an investigation into the influence of the free-volume space (f v ) defects on luminescence efficiency (LE) of erbium ions in Au 2 O 3 -doped PbO-B 2 O 3 -SeO 2 (PBS) glass ceramics. Glass ceramics containing fixed concentrations of Er 3+ ions and varied concentrations of Au 2 O 3 were synthesized. X-ray diffraction studies indicated that the samples contained Au 2 (SeO 3 ) 3 crystalline phase and nano gold metallic particles. The concentration of defects entrenched in the glass ceramics estimated in terms of Au 2 O 3 content using positron annihilation lifetime spectroscopy measurement indicated the highest content in the glass ceramic containing 0.075 mol% of Au 2 O 3 . Optical absorption and the photoluminescence (PL) spectra of the glass ceramics were studied in the visible region. The observed increase of PL efficiency was attributed to the enhanced concentration of free-volume imperfections in the samples. A perfect correlation could be achieved between the free-volume fraction and the PL efficiency of erbium ions in these glass ceramics., (© 2022 John Wiley & Sons Ltd.)

Zirconium doped calcium phosphate-based bioglasses are the most prominent bioactive materials for bone and dental repair and regeneration implants. In the present study, a 8ZnO-22Na 2 O-(24 - x)CaO-46P 2 O 5 -xZrO 2 (0.1 ≤ x ≤ 0.7, all are in mol%) bioglass system was synthesized by the conventional melt-quenching process at 1100 °C. The glass-forming ability and thermal stability of the glasses were determined by measuring the glass transition temperature ( T g ), crystallization temperature ( T c ), and melting temperature ( T m ), using differential thermal analysis (DTA). The biological activity of the prepared samples was identified by analyzing X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy-energy dispersive spectra (SEM-EDS), before and after immersion in simulated body fluid (SBF) for various intervals of 0, 1 and 5 days, along with the magnitude of pH and the degradation of glasses also evaluated. The obtained results revealed that the glass-forming ability and thermal stability of glasses increased with the increase in zirconia mol%. The XRD, FTIR, and SEM-EDS data confirmed a thin hydroxyapatite (HAp) layer over the sample surface after incubation in SBF for 1 and 5 days. Furthermore, the development of layer found to be increased with the increase of incubation time. The degradation of the glasses in SBF increased with incubation time and decreased gradually with the increase content of ZrO 2 mol% in the host glass matrix. A sudden rise in initial pH values of residual SBF for 1 day owing to ion leaching and increase of Ca 2+ and PO 4 3- ions and then decreased. These findings confirmed the suitability of choosing material for bone-related applications.

Aluminium doped phosphate based bioglasses have potential applications in the field of bone tissue engineering, because of their excellent bioactivity and biocompatibility along with high mechanical strength and controlled dissolution. In the present study, 8ZnO-22Na 2 O-(24-x)CaO-46P 2 O 5 -xAl 2 O 3 (where x = 0, 2, 4, 6, 8 and 10 mol%) glass system was synthesized and investigated by means of XRD, FTIR, SEM and EDS before and after immersion in SBF for 3, 7, 14 and 21days, the physic-chemical properties of the samples, including density and microhardness, evaluation of pH and weight loss of glasses in physiological fluid and cell cultural studies like cell viability, cytocompatability and cell proliferation by seeding rMSCs cells on the glass samples in order to throw some light on their structural properties. The results showed that, the density and Vickers hardness found to be increased with the increase in content of alumina due to the slight increase in the number of octahedrally coordinated Al 3+ ions and stronger ionic cross linkages due to insertion of Al 3+ ions between phosphate networks. The initial rise in pH and controlled solubility in SBF strongly supports the apatite layer development. The growth of the rMSCs cells on all samples showing good cytocompatability and proliferation up to 6 mol% Al 2 O 3 after that decreases slightly with an increase in alumina content due to network forming action of Al 3+ ions in zinc phosphate based glasses. The results confirmed the suitability of these glasses for clinical trials towards bone repair and regeneration resorbable implants., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Strontium Bismuth Borosilicate (SrBiBS as N) glasses doped with Tb 3+ ions (N: Tb) and co-doped with Sm 3+ /Tb 3+ (N: SmTb) were synthesized through the process of classical melt quenching. The structural and optical properties are investigated through energy dispersive spectroscopy; X-ray diffraction, Differential thermal analysis (DTA) and Fourier transform infrared spectra (FTIR), Optical absorption (OA) and photoluminescence (PL) spectral studies. X-ray diffraction indicates amorphous nature of glass. DTA curves explained the thermal stability and stress parameters of glasses. FTIR spectrum indicates existing vibrations of borate and silicate units. The absorption spectra have shown nine absorption bands of Tb 3+ ions in the visible and NIR regions, due to transitions from ground state 7 F 6 . In visible region, absorption spectra of co-doped glasses exhibited two bands of Tb 3+ and three bands of Sm 3+ with hyper sensitive transitions at 375 nm ( 7 F 6  →  5 G 6 ) and 401 nm ( 6 H 5/2  →  6 P 3/2 ). Photo Luminescence (PL) spectra of N: Tb and N: SmTb glasses is recorded at 375 nm excitation. N: Tb glasses have shown green emission corresponding to 5 D 4  →  7 F 5 transition. In all N: SmTb glasses, addition of Tb 3+ ions has enhanced Sm 3+ emission which is connected to quenching of Tb 3+ emission. Moreover, 0.8 mol% of Tb 3+ ions in co-doped glass (N: SmTb8) has shown maximum emission. The energy transfer process was inferred from shortening of decay times observed in N: SmTb glasses. The decay profiles fitted with Inokuti-Hirayama model suggests that the electric dipole-dipole interaction(S = 6) between Sm 3+ and Tb 3+ might dominate in energy transfer mechanism with probability P ET and energy transfer parameter Q of 113-173 S -1 and 9.9-12.0 respectively. The color chromaticity (CIE) coordinates from PL emission of N: Tb & N: SmTb glasses have covered Green, Orange red and yellow (warm-light) regions with coordinates in ranges of x = 0.39-0.62 and y = 0.34-0.56.The color temperatures in range of 1713 K-4258 K., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Novel amphiphilic Zn(II)phthalocyanines (ZnPcs) peripherally substituted with four and eight dimethylaminopyridinium units (ZnPc 1 and ZnPc 2 ) were synthesized by cyclotetramerization of the corresponding phthalonitriles. The effect of aggregation and photophysical (fluorescence quantum yields and lifetimes) and photochemical (singlet oxygen generation and photodegradation under light irradiation) properties was investigated. The chemosensing ability of ZnPcs toward explosive nitroaromatic compounds was explored in aqueous medium. This study demonstrates that ZnPc 1 and ZnPc 2 show fluorescence quenching behavior upon interaction with different nitro analytes and show unprecedented selectivity toward 2,4,6-trinitrophenol with a limit of detection (LOD) of 0.7-1.1 ppm with a high quenching rate constant ( K sv ) of 1.6-2.02 × 10 5 . The near-infrared (NIR) fluorescence in thin films was quenched efficiently because of the photoinduced electron-transfer process through strong intermolecular π-π and electrostatic interactions. The sensing process is highly reversible and free from the interference of other commonly encountered nitro analytes. Further, experiments were performed to demonstrate the use of ZnPcs as efficient heterogeneous photocatalysts in the reduction of nitro explosives. The smart dual performance of multicharged ZnPcs in aqueous media quantifies them as attractive candidates in developing sensor materials at the NIR region and to possibly convert the toxic explosives into useful scaffolds. These results provide an interesting perspective toward elaboration of stable fluorescent systems for the selective sensing behavior of nitro explosives and their facile heterogeneous catalytic behavior in the reduction reactions., Competing Interests: The authors declare no competing financial interest.

In this work we synthesized SrO-ZnO-P 2 O 5 glasses mixed with Pb 3 O 4 (heavy metal oxide) and doped with different amounts of Dy 2 O 3 (0.1 to 1.0 mol%). Subsequently their emission and decay characteristics were investigated as a function of Dy 2 O 3 concentration. The emission spectra exhibited three principal emission bands in the visible region corresponding to 4 F 9 /2  →  6 H 15 /2 (482 nm), 6 H 13 /2 (574 nm) and 6 H 11 /2 (663 nm) transitions. With increase in the concentration of Dy 2 O 3 (upto 0.8 mol%) a considerable increase in the intensity of these bands was observed and, for further increase, quenching of photoluminescence (PL) output was observed. Using emission spectra, various radiative parameters were evaluated and all these parameters were found to increase with increase in Dy 2 O 3 concentration. The Y/B integral emission intensity ratio of Dy 3 + ions evaluated from these spectra exhibited a decreasing trend with increase in the Dy 2 O 3 concentration up to 0.8 mol%. Quenching of luminescence observed in the case of the glasses doped with 1.0 mol% is attributed to clustering of Dy 3 + ions. The quantitative analysis of these results together with infra-red (IR) spectral studies indicated that 0.8 mol% is the optimum concentration of Dy 3 + ions needed to achieve maximum luminescence efficiency. Copyright © 2016 John Wiley & Sons, Ltd., (Copyright © 2016 John Wiley & Sons, Ltd.)

BaO-B 2 O 3 -P 2 O 5 glasses doped with a fixed concentration of Tb 3 + ions and varying concentrations of Al 2 O 3 were synthesized, and the influence of the Al 3 + ion concentration on the luminescence efficiency of the green emission of Tb 3 + ions was investigated. The optical absorption, excitation, luminescence spectra and fluorescence decay curves of these glasses were recorded at ambient temperature. The emission spectra of terbium ions when excited at 393 nm exhibited two main groups of bands, corresponding to 5 D 3  →  7 F j (blue region) and 5 D 4  → 7F j (green region). From these spectra, the radiative parameters, viz., spontaneous emission probability A, total emission probability A T , radiative lifetime τ and fluorescent branching ratio β, of different transitions originating from the 5 D 4 level of Tb 3 + ions were evaluated based on the Judd-Ofelt theory. A clear increase in the quantum efficiency and luminescence of the green emission of Tb 3 + ions corresponding to 5 D 4  →  7 F 5 transition is observed with increases in the concentration of Al 2 O 3 up to 3.0 mol%. The improvement in emission is attributed to the de-clustering of terbium ions by Al 3 + ions and also to the possible admixing of wave functions of opposite parities. Copyright © 2016 John Wiley & Sons, Ltd., (Copyright © 2016 John Wiley & Sons, Ltd.)

Multi-component CaF2-Bi2O3-P2O5-B2O3 glasses doped with different concentrations of Cr2O3 were crystallized through heat treatment. The prepared glass ceramic samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and differential thermal analysis (DTA). Spectroscopic studies viz., optical absorption, Fourier transform infrared (FTIR), Raman and electron paramagnetic resonance (EPR) were carried out. The XRD, SEM and DTA studies indicated that the samples contain different crystalline phases. Results of optical absorption and EPR studies pointed out the gradual conversion of chromium ions from Cr(3+) state to Cr(6+) state with an increase of Cr2O3 content from 0.1 to 0.5 mol%. The results of FTIR, Raman and EPR studies revealed that Cr(6+) ions participate in the glass network in tetrahedral positions and seemed to increase the polymerization of the glass ceramics. The quantitative analysis of results of the spectroscopic studies further indicated that the glasses crystallized with low concentration of Cr2O3 are favourable for solid state laser devices., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Soda lime silica borate glasses mixed with different concentrations of TiO2 are synthesized by the melt-quenching technique. As a part of study on bioactivity of these glasses, the samples were immersed in simulated body fluid (SBF) solution for prolonged times (~21 days) during which weight loss along with pH measurements is carried out at specific intervals of time. The XRD and SEM analyses of post-immersed samples confirm the formation of crystalline hydroxyapatite layer (HA) on the surface of the samples. To assess the role of TiO2 on the formation of HA layer and degradability of the samples the spectroscopic studies viz. optical absorption and IR spectral studies on post- and pre-immersed samples have been carried out. The analysis of the results of degradability together with spectroscopic studies as a function of TiO2 concentration indicated that about 6.0 mol% of TiO2 is the optimal concentration for achieving better bioactivity of these glasses. The presence of the maximal concentration octahedral titanium ions in this glass that facilitates the formation of HA layer is found to be the reason for such a higher bioactivity., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Glasses of the composition (30-x)PbO-5Bi2O3-65SiO2: xNiO (with x ranging from 0 to 1.0 mol%) were synthesized. A variety of spectroscopic studies, viz., IR, Raman optical absorption and luminescence properties of these glasses have been carried out as a function of NiO concentration. The analysis of results of all these studies has indicated that the nickel ions occupy both octahedral and tetrahedral positions. However, with the increase of NiO concentration the octahedral occupancy of Ni(2+) ions prevailed over the tetrahedral ions. The luminescence spectra of these glasses have exhibited a broad NIR emission band in region 1100-1500 nm. This band is identified as being due to (3)T2(3F)→(3)A2(3F) octahedral transition of Ni(2+) ions. The luminescence efficiency and cross section have been found to be the highest for the glass containing the highest concentration of NiO. The reasons for such high luminescence efficiency have been discussed in the light of structural variations taking place in the host glass network., (Copyright © 2015 Elsevier B.V. All rights reserved.)

MgO-PbO-B2O3-SiO2-Nd2O3-Dy2O3 glasses are prepared by melt-quenching technique. The samples are characterized by X-ray diffraction (XRD), optical absorption, luminescence and Fourier transform infrared (FT-IR) spectral studied. XRD analysis evidently indicates that the prepared samples are fully amorphous nature. From the optical absorption spectra, the bonding environment surrounding the Dy(3+) and their energy level scheme in glass network is analyzed. Enhancement of Dy(3+) emission by non-radiative energy transfers from Nd(3+) has been observed here. The samples emits intensive bluish yellow color from the (4)F9/2→(6)H15/2, (6)H13/2 transition of Dy(3+) ions in these glasses which are nearer to white light and it is also supported by the chromaticity color coordinates. The FT-IR spectra reveal that network connectivity is increased with replacement of bonds B-O-B, Si-O-Si by more resistant B-O-Si bonds with gradually increasing the content of Dy(3+) ions in the glass network. Along with spectroscopic parameters some physical parameters like density, refractive index etc. are measured for the glasses., (Copyright © 2013 Elsevier B.V. All rights reserved.)

The glasses of the composition 19Na(2)SO(4)-20MO-60P(2)O(5): 1.0Ho(2)O(3)/1.0Er(2)O(3) (M=Mg, Ca, and Ba) have been synthesized. Optical absorption and fluorescence spectra (in the spectral range 350-2100 nm were studied at ambient temperature. The spectra were characterized using Judd-Ofelt theory. From the luminescence spectra, various radiative properties like transition probability A, branching ratio β and the radiative life time τ for blue (B), green (G) and red (R) emission levels of these glasses have been evaluated. The energy transfer between the two rare earth ions (Ho(3+) and Er(3+)) in co-doped Na(2)SO(4)-MO-P(2)O(5) glass systems in the visible and NIR regions has also been investigated. Highest intensity, the highest quantum efficiency and maximum energy transfer with low phonon losses of B, G, and R lines has been observed in BaO mixed glasses. The reasons for such higher values of these parameters have been discussed in the light of varying field strengths at the rare earths ion site due to replacement of one modifier oxide with the other. The enhanced intensity of NIR emission (at 2.0 μm) has also been discussed in terms of cross relaxation of Er(3+) ions from (4)I(13/2) level to (5)I(7) of Ho(3+) ions., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Li(2)O-ZrO(2)-SiO(2):Nd(3+) glasses mixed with Nb(2)O(5), Ta(2)O(5) and La(2)O(3) were prepared. Optical absorption and photoluminescence spectra of these glasses have been recorded at room temperature. The Judd-Ofelt theory was successfully applied to characterize Nd(3+) spectra of all the three glasses. From this theory, various radiative properties like transition probability A, branching ratio β(r), the radiative lifetime τ(r), for (4)F(3/2) emission level in the spectra of these glasses has been evaluated. The radiative life time for (4)F(3/2) level of Nd(3+) ions has also been measured and quantum efficiencies were estimated. Among the three glasses studied, the La(2)O(3) mixed glass has exhibited the highest quantum efficiency. The reasons for such higher value have been discussed based on the relationship between the structural modifications taking place around the Nd(3+) ions., (Copyright © 2011 Elsevier B.V. All rights reserved.)

PbO-Sb(2)O(3)-B(2)O(3) glasses mixed with different concentrations of CoO (ranging from 0 to 2.0 mol%) were crystallized. The samples were characterized by x-ray diffraction, scanning electron microscopy and differential scanning calorimetric techniques. The x-ray diffraction and scanning electron microscopic studies have revealed the presence of CoSb(2)O(6), Co(2.33)Sb(0.67)O(4), Pb(5)Sb(2)O(8),Pb(3)(SbO(4))(2), PbB(4)O(7) and Co(3)O(4) crystalline phases in these samples. The DSC studies have indicated the spreading of the crystallization from the inside to the surface of the samples as the concentration of the crystallizing agent is increased. The IR and Raman spectroscopic studies have pointed out the existence of conventional BO(3), BO(4), SbO(4) and also Co(III)-O structural units in the glass ceramic samples. These studies have further indicated the decreasing concentration of symmetrical structural vibrational groups with increase in the concentration of CoO. The results of various studies, namely dielectric properties over a range of frequency and temperature, photo-induced birefringence, optical absorption, fluorescence and magnetic susceptibility at room temperature of PbO-Sb(2)O(3)-B(2)O(3):CoO glass ceramics, have also been reported. The variations observed as a function of the concentration of crystallizing agent in all these properties have been analyzed in the light of different oxidation states and environments of cobalt ions in the glass ceramic network.