Thermal quenching of photoluminescence represents a significant obstacle to practical applications such as lighting, display, and photovoltaics. Herein, a novel strategy is established to enhance upconversion luminescence at elevated temperatures based on the use of negative thermal expansion host materials. Lanthanide‐doped orthorhombic Yb2W3O12 crystals are synthesized and characterized by in situ X‐ray diffraction and photoluminescence spectroscopy. The thermally induced contraction and distortion of the host lattice is demonstrated to enhance the collection of excitation energy by activator ions. When the temperature is increased from 303 to 573 K, a 29‐fold enhancement of green upconversion luminescence in Er3+ activators is achieved. Moreover, the temperature dependence of the upconversion luminescence is reversible. The thermally enhanced upconversion is developed as a sensitive ratiometric thermometer by referring to a thermally quenched upconversion.
Sustained cardiac hypertrophy (CH) is related to a variety of physiological as well as pathological stimuli and eventually increases the risk of heart failure. HOTAIR has been identified as a competing endogenous RNA in multiple human biological processes. Whether lncRNA-HOTAIR is involved in the progress of CH and how it works still remain unknown. Herein, we found that HOTAIR was down-regulated, while miR-19 was up-regulated in both heart tissues from TAC-operated mice in vivo and cultural cardiomyocytes treated with Ang-II in vitro by real-time PCR. Meanwhile, HOTAIR expression was negatively correlated with miR-19 in TAC-operated mice. HOTAIR overexpression reduced cell surface area and the expression of hypertrophic markers ANP, BNP, and β-MHC in response to Ang-II stimulation as well as knockdown of miR-19. The further molecular mechanisms of HOTAIR action in CH demonstrated that HOTAIR may act as a competing endogenous RNA (ceRNA) for miR-19, thereby modulating the dis-inhibition of its endogenous target PTEN and playing an important role in inhibiting CH progress. These findings reveal a novel function of LncRNAs, which conduce to an extensive understanding of CH and provide novel research directions and therapeutic options for treating this disease.
Lanthanide-doped ScF3 nanoparticles
are synthesized
and explored for thermal enhancement of upconversion. A hot-injection
method is developed to control the formation of ScF3 nanoparticles
with a core–shell nanostructure of uniform size and morphology.
Temperature dependence of the upconversion emission is investigated
in the temperature range from 168 to 308 K. In contrast to typical
NaYF4:Yb/Er@NaYF4 nanoparticles that display
thermally quenched emissions, a 3.7-fold enhancement of the upconversion
emission is recorded for the ScF3:Yb/Er@ScF3 nanoparticles as the temperature is increased from 168 to 248 K
because of the negative thermal expansion of the ScF3 host
lattice. Besides, the emission profiles of the nanocrystals also display
a strong temperature dependence, enabling convenient ratiometric thermometry
with a relative sensitivity of 1.73%·K–1 at
168 K. As the core–shell nanoparticles are minimally susceptible
to surface quenching, our findings may inspire new ideas for developing
thermally enhanced upconversion nanoparticles with high emission intensities.
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