Investigation of Host-Sensitized Luminescence of Trivalent Lanthanide Doped Yttrium Phosphate using VUV Spectroscopy

Host-sensitized luminescence of yttrium phosphate doped with trivalent lanthanide elements prepared via two synthetic approaches was studied using VUV spectroscopy. A correlation between an unusually intense 150 nm excitation intensity and the ground state energy level of select trivalent lanthanide elements was proposed. Using spectroscopy, the host-to-activator transfer efficiencies of YPO4:Ln3+ (Ln3+ = Sm3+, Eu3+ and Tb3+) were evaluated for two synthetic approaches. Electron-hole pair trapping efficiencies and Sloss values were calculated using published kinetic models

VUV Optical Properties of Rare Earth Doped YPO4 Prepared by Different Routes

The optical properties of nanocrystalline YPO4:Ln3+ (Ln = Eu, Sm, Tb) prepared via co-precipitation are compared to larger crystallites of YPO4:Ln3+ prepared via traditional solid state reaction. In larger crystals (~330 nm) a distinct peak is observed at 150 nm in the excitation spectra, the intensity of which decreases markedly in smaller crystals (~20 nm). Using excitation and reflectance spectroscopy, host–to–activator energy transfer efficiencies were calculated for Y1-xPO4:Lnx3+ (0.01 ≤ x ≤ 0.10). From the transfer efficiency data, we estimate that trapping by Eu3+ and Sm3+ is at least five times more efficient than trapping by Tb3+ for excitation at the band edge. The fraction of energy lost to the surface or grain boundaries for excitation at 150 nm and 138 nm is also estimated. We propose that in the samples prepared via co-precipitation, an amorphous phase forms at grain boundaries that is responsible for the loss of efficiency under 150 nm excitation

The IDENTIFY study: the investigation and detection of urological neoplasia in patients referred with suspected urinary tract cancer - a multicentre observational study

Objective To evaluate the contemporary prevalence of urinary tract cancer (bladder cancer, upper tract urothelial cancer [UTUC] and renal cancer) in patients referred to secondary care with haematuria, adjusted for established patient risk markers and geographical variation. Patients and Methods This was an international multicentre prospective observational study. We included patients aged ≥16 years, referred to secondary care with suspected urinary tract cancer. Patients with a known or previous urological malignancy were excluded. We estimated the prevalence of bladder cancer, UTUC, renal cancer and prostate cancer; stratified by age, type of haematuria, sex, and smoking. We used a multivariable mixed-effects logistic regression to adjust cancer prevalence for age, type of haematuria, sex, smoking, hospitals, and countries. Results Of the 11 059 patients assessed for eligibility, 10 896 were included from 110 hospitals across 26 countries. The overall adjusted cancer prevalence (n = 2257) was 28.2% (95% confidence interval [CI] 22.3–34.1), bladder cancer (n = 1951) 24.7% (95% CI 19.1–30.2), UTUC (n = 128) 1.14% (95% CI 0.77–1.52), renal cancer (n = 107) 1.05% (95% CI 0.80–1.29), and prostate cancer (n = 124) 1.75% (95% CI 1.32–2.18). The odds ratios for patient risk markers in the model for all cancers were: age 1.04 (95% CI 1.03–1.05; P < 0.001), visible haematuria 3.47 (95% CI 2.90–4.15; P < 0.001), male sex 1.30 (95% CI 1.14–1.50; P < 0.001), and smoking 2.70 (95% CI 2.30–3.18; P < 0.001). Conclusions A better understanding of cancer prevalence across an international population is required to inform clinical guidelines. We are the first to report urinary tract cancer prevalence across an international population in patients referred to secondary care, adjusted for patient risk markers and geographical variation. Bladder cancer was the most prevalent disease. Visible haematuria was the strongest predictor for urinary tract cancer

New Synthesis of Novel Phosphor for LED Technology: Sr3Y2(BO3)4:Eu Using Sr3B2O6:Eu and SrB4O7:Eu Precursors

Phosphors, used in plasma screens, medical imaging, and LED lighting, are materials that absorb energy and emit light. A promising activator for use in phosphors is divalent europium (Eu2+). Depending on the host, this dopant can emit anywhere in the visible spectrum. However, in many host compounds, it is difficult to dope Eu2+ due to the stability of trivalent europium (Eu3+). The literature indicates that the phosphor SrB4O7 readily incorporates Eu2+ into its structure, but that Sr3B2O6 does not. Here, we show that we can increase the ratio of Eu2+ emission to Eu3+ emission in Sr3B2O6:Eu by using SrB4O7:Eu2+ as a precursor. Divalent europium emission in Sr3Y2(BO3)4 has not been reported in the literature. To look for Eu2+ emission, we prepared samples of Sr3Y2(BO3)4 by using Sr3B2O6 and SrB4O7 precursors. Samples of SrB4O7:Eu precursor were prepared using traditional methods: grinding stoichiometric amounts of strontium carbonate, boric acid, and europium oxide and firing in a reducing atmosphere. To make the Sr3B2O6:Eu precursor, portions of the SrB4O7:Eu precursor were ground with stoichiometric amounts of SrCO3, and samples were fired in a reducing atmosphere again. To transform the precursors, the SrB4O7 precursor was ground with stoichiometric amounts of yttrium oxide and strontium carbonate, and fired in a reduction furnace. Sr3B2O6 precursor was ground with stoichiometric amounts of yttrium oxide and boric acid, and fired in a reduction furnace. We show that undoped samples of Sr3B2O6 and SrB4O7 can be transformed phase-pure to Sr3Y2(BO3)4. This method may lead to previously unmade novel phosphors