Noncontact optical thermometers have attracted interest of scientific researchers due to their reliability and accuracy. However, the use of optical thermometers based on the luminescence intensity ratio of two thermally coupled energy levels (TCELs) is limited by the Boltzmann factor of the energy difference between them. Here, we propose a strategy to improve temperature sensing by utilizing the nonthermally coupled energy levels (NTCELs) of Tm3+ and Er3+ ions. We studied the upconversion luminescence (UCL) and temperature-sensing properties of Yb3+/Er3+/Tm3+-codoped 12CaO·7Al2O3 single crystals. The UCL color of these crystals changes from white to green as the temperature increases from 323 to 623 K, and they exhibit a large temperature dependence. The maximum relative sensitivity based on NTCELs (Tm:1G4/Er:3H11/2) is 3.073% K–1, which is approximately six times higher than that achieved using TCELs (Er3+:2H11/2/4S3/2). The maximum absolute sensitivity-based luminescence intensity ratio of NTCELs (I 800/870) is 12.5% K–1 at 323 K, which is the highest absolute sensitivity for Er3+ and Tm3+ ions. This work provides a promising strategy to realize an accurate and effective temperature sensor via tuning of dual-mode upconversion in a single crystal.
Aim. Patients with diabetic ketosis often exhibit albuminuria. We previously found that acute hyperglycaemia can cause nephrotoxic injury. Here, we explored whether an excessive ketone body level causes kidney injury and the potential underlying mechanism. Methods. Fifty-six type 2 diabetes without ketosis (NDK group), 81 type 2 diabetes with ketosis (DK group), and 38 healthy controls (NC group) were enrolled. Clinical data were collected before and after controlling diabetic ketosis. Beta-hydroxybutyric acid (BOHB), an AKT activator, an AKT inhibitor, or plasmids encoding DAB2 were transformed into human renal proximal tubule epithelial cells (HK-2 cells). Results. The urinary albumin-to-creatinine ratio (ACR), transferrin (TF), immunoglobulin G (IgG), Beta2-microglobulin (β2-MG), retinol-binding protein (RBP), N-acetyl-beta-glucosaminidase (NAG), and Beta-galactosidase (GAL) were higher in the DK than NC and NDK groups. The proportion of patients with an increased urinary level of TF, IgG, β2-MG, RBP, NAG, or GAL was higher in the DK group too. After controlling ketosis, urinary microalbumin, TF, IgG, β2-MG, and RBP decreased significantly. In HK-2 cells, albumin endocytosis and megalin expression decreased with increasing BOHB concentration. Compared with BOHB treatment, BOHB with AKT activator significantly increased the DAB2, megalin levels and albumin endocytosis; the AKT inhibitor treatment exhibited the opposite effects. Compared with BOHB treatment, megalin expression and albumin endocytosis were significantly increased after BOHB with DAB2 overexpression treatment. Conclusions. Patients with diabetic ketosis may suffer from glomerular and tubular injuries that recover after ketosis control. High concentrations of BOHB downregulate megalin expression by inhibiting the AKT/DAB2/megalin signalling pathway and albumin endocytosis in proximal renal tubules.
Developing high-resolution, high-accuracy fluorescent thermometers is challenging. In this study, the optical properties and thermal sensing of Yb-, Tm-, and Eu-co-doped C12A7 (C12A7:Yb/Eu/Tm), with flower-like structure upconversion microparticles, were studied. Eu3+ doping induced an approximately 6-fold change in the upconversion luminescence (UCL) output in comparison with C12A7:Yb/Tm microparticles. The maximum relative temperature sensitivity (S) of C12A7:Yb/Eu/Tm reached 3.0% K–1, representing an approximately 5-fold difference compared with the value of C12A7:Yb/Tm. In particular, the multicolor upconversion emission of C12A7:Yb/Eu/Tm can easily change from blue to white UCL with increasing temperature. Moreover, the band structure, total density, and optical coefficient of C12A7:Yb/Eu/Tm were investigated via density functional theory. The total density of O atoms increased in comparison with the total density of pure C12A7, indicating that substitution of Ca2+ by Yb/Eu/Tm produced positive vacancies on the cage structure. The optical coefficient of C12A7 was improved by the Yb/Eu/Tm dopant. The thermally regulated multicolor characteristics and thermally coupled energy levels of Tm3+ provide “dual adjustment temperature sensing”, which is a promising strategy for realizing accurate and effective temperature sensors.
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