Heat Treatment Effect on Eu 3+

Glass systems of 73TeO2-4BaO-3Bi2O3-2Eu2O3-xAg (in molar ratio where x = 0, 1, 2, and 3) compositions have been successfully synthesized. Silver nanoparticles were obtained with the employment of heat treatment (HT) procedure executed at 350°C. Glass transition temperatures of different compositions have been determined through DSC measurements. XRD results presented characteristic amorphous halo indicating lack of long range order in the samples. FTIR structural studies revealed that glass matrix is mainly composed of TeO3 and TeO4 species and is stable after different applied heat treatment times. X-ray photoelectron spectroscopy (XPS) measurements confirmed that in selected samples part of Ag ions changed oxidation state to form Ag0 species. TEM measurements revealed nanoparticles of size in the range of 20–40 nm. UV-vis absorption results demonstrated characteristic transitions of Eu3+ ions. Additionally, UV-vis spectra of samples heat-treated for 6, 12, 24, and 48 hours presented bands related to silver nanoparticles. Photoluminescence (PL) studies have been performed with excitation wavelength of λexc=395 nm. Obtained spectra exhibited peaks due to 5D0-7FJ (where J=2,3,4) and 5D1-7FJ (where J=1,2,3) transitions of Eu3+. Moreover, luminescence measurement indicated enhancement of rare earth ions emissions in several of the annealed samples. Increase of emission intensity of about 35% has been observed

Influence of Selected Saccharides on the Precipitation of Calcium-Vaterite Mixtures by the CO₂ Bubbling Method

Calcium carbonate is a compound existing in living organisms and produced for many biomedical applications. In this work, calcium carbonate was synthesized by a CO2 bubbling method using ammonia as a CO2 absorption promotor. Glucose, fructose, sucrose, and trehalose were added into the reaction mixture to modify characteristics of precipitated calcium carbonate particles. To determine the polymorphic form of produced calcium carbonate particles, Fourier transform infrared spectroscopy (FTIR-ATR) and X-ray diffraction (XRD) analysis were performed. Scanning electron microscopy (SEM) was used to estimate the size and shape of produced particles. Mixtures of vaterite and calcite were synthesized in all experiments. The percentage content of the vaterite in the samples depended on used additive. The highest concentration of vaterite (90%) was produced from a solution containing sucrose, while the lowest concentration (2%) was when fructose was added. Saccharides affected the rate of CO2 absorption, which resulted in a change in the precipitation rate and, therefore, the polymorphic composition of calcium carbonate obtained in the presence of saccharides was more varied

Au–Si plasmonic platforms: synthesis, structure and FDTD simulations

Plasmonic platforms based on Au nanostructures have been successfully synthesized by directional solidification of a eutectic from Au and the substrate. In order to determine homogeneous shape and space distribution, the influence of annealing conditions and the initial thickness of the Au film on the nanostructures was analyzed. For the surface morphology studies, SEM and AFM measurements were performed. The structure of platforms was investigated using XRD and XPS methods. Structural investigations confirmed, that nanostructures consist of metallic Au, growing along the [111] direction. The most homogeneous seems to be the platform obtained by solidification of a 2.8 nm Au film, annealed at 550 °C for 15 min. This sample was subsequently chosen for theoretical calculations. Simulations of electromagnetic field propagation through the produced samples were performed using the finite-difference time domain (FDTD) method. The calculated absorbance, as a result of the FDTD simulation shows a quite good agreement with experimental data obtained in the UV–vis range

From Structure to Luminescent Properties of B2O3-Bi2O3-SrF2 Glass and Glass-Ceramics Doped with Eu3+ Ions

Glass-ceramics with the composition B2O3-Bi2O3-SrF2 were synthesized by the conventional melt-quenching technique and subsequent crystallization of the parental glasses. The temperature at which the ceramization was carried out was selected based on differential scanning calorimetry (DSC) analysis. The structure of the studied materials and the formation of SrF2 nanocrystals were confirmed by the Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) techniques. It was found that the amount of strontium fluoride introduced into the parental borate-bismuth glass has a significant impact on the growth of SrF2 nanocrystals. In particular, the influence of the crystalline SrF2 phase on luminescence intensity and kinetics was studied using Eu2O3-doped samples. An increase in luminescence intensity was observed in the samples in which SrF2 nanocrystals were formed. This is most likely related to the fact that some of the Eu3+ ions were (after annealing of the glass) located in the crystalline structure of strontium fluoride. This was confirmed both by the luminescence lifetime obtained based on the luminescence decay curves and the calculated Judd–Ofelt parameters, Ω2 and Ω4. The results achieved confirm that the glasses and glass-ceramics described in this work could be considered as a new phosphor for light-emitting diodes (LEDs)

Transformation of bimetallic Ag–Cu thin films into plasmonically active composite nanostructures

Abstract Formation of plasmonically active silver, copper and composite silver-copper nanostructures were studied in this paper. Metallic nanostructures were fabricated by thermal disintegration, so called dewetting, of the thin films in an argon atmosphere. The formation process of the nanostructures was in-situ observed by a novel method, based on resistance measurements. The influence of the material and thickness of the initial thin film on temperature of their disintegration was investigated. Electrical measurements were validated by scanning electron microscopy observations, while metallic the behavior of nanostructures was studied by XPS method. The formation of silver-copper nanocomposite structures was confirmed by UV–vis spectroscopy. Plasmon resonance with two characteristic peaks for nanocomposite structures was observed

Immune Response to Vaccination against COVID-19 in Breastfeeding Health Workers

Background: Initially, there were no data on the safety of COVID-19 vaccines in lactating women. The aim of our study was to evaluate the immune response to COVID-19 vaccinations in breastfeeding women. Methods: The study included 32 breastfeeding women who, regardless of the study, had decided to be vaccinated. Maternal serum and breast milk samples were simultaneously collected on days 8 ± 1, 22 ± 2, 29 ± 3, and 43 ± 4 after the first dose of the vaccine. The immune response was assessed by determining the presence of anti-SARS-CoV-2 IgG and IgA. Results: The breast milk IgG level was detectable (6.50 ± 6.74, median 4.7, and maximum 34.2 BAU/mL) and highly correlated to serum IgG level (rS 0.89; p < 0.001). The breast milk ratio of IgA to the cut-off value was higher in serum IgA-positive (4.18 ± 3.26, median 2.8, and maximum >10) than in serum IgA-negative women (0.56 ± 0.37, median 0.5, and maximum 1.6; p < 0.001). The highest concentrations of serum and breast milk antibodies were observed on day 29 ± 3 with a decrease on day 43 ± 4. Conclusion: The immune response to the vaccination against SARS-CoV-2 is strongest 7 ± 3 days after the second dose of the vaccine. Lactating mothers breastfeeding their children after vaccination against SARS-CoV-2 may transfer antibodies to their infant