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The second near-infrared (NIR II) response photon up-conversion (UC) materials show great application prospects in the fields of biology and optical communication. However, it is still an enormous challenge to obtain efficient NIR II response materials. Herein, we develop a series of Er3+ doped ternary sulfides phosphors with highly efficient UC emissions under 1532 nm irradiation. β-NaYS2:Er3+ achieves a visible UC efficiency as high as 2.6%, along with high brightness, spectral stability of lights illumination and temperature. Such efficient UC is dominated by excited state absorption, accompanied by the advantage of long lifetimes (4I9/2, 9.24 ms; 4I13/2, 30.27 ms) of excited state levels of Er3+, instead of the well-recognized energy transfer UC between sensitizer and activator. NaYS2:Er3+ phosphors are further developed for high-performance underwater communication and narrowband NIR photodetectors. Our findings suggest a novel approach for developing NIR II response UC materials, and simulate new applications, eg., simultaneous NIR and visible optical communication. Development of efficient upconversion (UC) phosphors that emit under irradiation in the NIR II region is challenging - most UC materials rely on the presence of sensitizers absorbing at shorter wavelengths. Here, authors synthesize Er3+ doped ternary sulfides phosphors with visible UC efficiency up to 2.6% and long emission lifetimes under 1532 nm irradiation, via an excited state absorption mechanism. [ABSTRACT FROM AUTHOR]

Background and Purpose: Dopamine agonists targeting D2 receptor have been used for decades in treating pituitary adenomas. There has been little clear evidence implicating the canonical G protein signalling as the mechanism by which D2 receptor suppresses the growth of pituitary tumours. We hypothesize that β-arrestin2-dependent signalling is the molecular mechanism dictating D2 receptor inhibitory effects on pituitary tumour growth.Experimental Approach: The involvement of G protein and β-arrestin2 in bromocriptine-mediated growth suppression in rat MMQ and GH3 tumour cells was assessed. The anti-growth effect of a β-arrestin2-biased agonist, UNC9994, was tested in cultured cells, tumour-bearing nude mice and primary cultured human pituitary adenomas. The effect of G protein signalling on tumour growth was also analysed by using a G protein-biased agonist, MLS1547, and a Gβγ inhibitor, gallein, in vitro.Key Results: β-arrestin2 signalling but not G protein pathways mediated the suppressive effect of bromocriptine on pituitary tumour growth. UNC9994 inhibited pituitary tumour cell growth in vitro and in vivo. The suppressive function of UNC9994 was obtained by inducing intracellular reactive oxygen species generation through downregulating mitochondrial complex I subunit NDUFA1. The effects of Gαi/o signalling and Gβγ signalling via D2 receptor on pituitary tumour growth were cell-type-dependent.Conclusion and Implications: Given the very low expression of Gαi/o proteins in pituitary tumours and the complexity of the responses of pituitary tumours to G protein signalling pathways, our study reveals D2 receptor β-arrestin2-biased ligand may be a more promising choice to treat pituitary tumours with improved therapeutic selectivity. [ABSTRACT FROM AUTHOR]

Multicolor upconversion luminescence materials show significantly applications in materials science. In this paper, the novel Yb3+‐sensitized Na3La(VO4)2 upconversion luminescence crystals are synthesized by the solid‐state reaction method. Three primary colors upconversion luminescence are successfully achieved in Na3La(VO4)2:Yb3+,Tm3+, Na3La(VO4)2:Yb3+,Er3+, and Na3La(VO4)2:Yb3+,Ho3+ crystals excited by the single 980 nm LD. Multicolor upconversion luminescence can be obtained by simply adjusting the combination ratios of these three samples. Luminescence mechanisms of the Yb3+‐sensitized system are discussed in detail. In the Na3La(VO4)2 host material, the Yb3+/Ho3+ codoped system exhibits unusual red upconversion luminescence based on the short decay time of Ho3+ ion 5I6 level, which provides the possibility of three primary color luminescence under 980 nm excitation. [ABSTRACT FROM AUTHOR]

The development of noncontact thermal probe based on stable inorganic materials of trivalent lanthanide (Ln3+) doped phosphors with nontoxicity is of vital importance for their promising applications in bio‐medical fields. Here we explore the upconversion luminescence and thermal sensing properties of Er3+, Yb3+ co‐doped oxysulfide in a broad temperature range of 300‐583 K. It was found that constructing an active shell with an optimum concentration of sensitizers is an efficient way to improve both the luminescent intensities and thermal sensitivity. Compared with the core‐only sample, the luminescent intensity of the Y2O2S: Er3+, Yb3+@ Y2O2S: 5%Yb3+ sample is significantly enhanced by 12‐fold at excitation of 980 nm. While further increasing the Yb3+ concentration in the shell activates new quenching pathways of Er3+ → Yb3+ → quencher from the core to the shell. Similar quenching mechanisms are also observed at excitation of 1550 nm. These energy transfer processes and luminescence mechanisms are verified in the fluorescence decay measurements. Furthermore, coating the core sample with an active shell doped by 10% Yb3+ enhances the thermal sensitivity by 30%, holding a high and stable sensitivity more than 50 × 10−4 K−1 in a broad temperature range of 423‐573 K at 980 nm excitation. In addition, at the much safer excitation wavelength of 1550 nm, this sample achieved the maximum sensitivity of 45 × 10−4 K−1 at 503 K. Our work contributes a feasible and versatile way to promote the luminescence and thermal sensing properties of Ln3+‐based materials, combining with the nontoxic oxysulfide host, indicating their potential applications as safe fluorescent and temperature nano‐probes in bio‐field. [ABSTRACT FROM AUTHOR]

Uniform spindle‐like micro‐rods NaLa(WO4)2:Yb3+,Er3+ phosphors are prepared by the solvothermal method in the text. Controllable morphology of NaLa(WO4)2 crystal can be obtained by adjusting the prepared temperature, PH value, complexing agent content, and solvent ratio. Uniform NaLa(WO4)2:Yb3+,Er3+ micro‐rods of 1.8 μm in length and 0.5 μm in width are synthesized at a low temperature of 120°C. The prepared NaLa(WO4)2:Yb3+,Er3+ phosphors present green upconversion luminescence under 980 nm excitation, luminescence intensity reaches to maximum at the Yb3+ and Er3+ concentration of 6 and 2 mol%. The temperature performance of the NaLa(WO4)2:Yb3+,Er3+ phosphors are evaluated based on thermal coupling technology. Temperature dependence of the two green emissions ratio of Er3+ ion is obtained, and the sensitivity of the sample can be calculated, the maximum sensitivity of NaLa(WO4)2:Yb3+,Er3+ is up to 0.019 K−1 at the sample temperature of 564 K. [ABSTRACT FROM AUTHOR]

The thermal effects of Er/Yb-doped NaYF4 phosphor induced by 980/1510 nm laser diode irradiation were intuitively and contrastively investigated using an infrared thermal imaging technology with real-time online monitoring. The Yb3+/Er3+ codoped materials have strong thermal effects and high-temperature elevation under 980 nm irradiation. However, the severe thermal effects of materials with higher Er3+ ion doping concentration are remarkably attributed to the cross relaxation between the Er3+ ions under 980 nm irradiation. The energy transfer between Er3+ and Yb3+ ions in Er3+/Yb3+-codoped materials also contributes to the thermal effects under 1510 nm laser diode irradiation. Under the same testing conditions, the temperature elevation ∆T of samples induced by 1510 nm laser diode irradiation is lower than that induced by 980 nm laser diode irradiation. The temperature rising rate and elevation ∆T value of samples depend on the ion doping concentration and power density of the laser diode excitation. The internal temperature of the samples exhibits deep temperature gradient under 980/1510 nm laser diode irradiation. By comparing the two kinds of thermometry methods, the temperature value calculated by fluorescence intensity ratio is almost similar to that obtained through infrared thermal imaging technology under higher excitation power pumping. [ABSTRACT FROM AUTHOR]

Lanthanide ions have abundant excited-state channels which result in a radiation relaxation process generally accompanied by a non-radiation relaxation process. However, non-radiation relaxation processes will consume the activation energy and reduce the luminescence efficiency of the phosphor. Two lasers with an excitation energy which matched the ground state absorption and excited state absorption of ions were used to excite the phosphors to avoid the non-radiation relaxation process. This approach can achieve the purpose of populating specific states of the lanthanide ions, and furthermore effectively tunes the luminescence intensity and color output of the sample. Results show that the red emission intensity of the sample is significantly improved and this is caused by populating the 4 F 9/2 level under simultaneous 1510 nm and 980 nm excitation. Then when the 1510 nm and 808 nm co-operate to excite the sample, the green emission obtained increased sharply because the 2 H 11/2 / 4 S 3/2 states were efficiently populated. As a proof-of-concept experiment, this new approach has potential in the applications of solar cells., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)