Study on the characteristic curve of laser-induced delayed luminescence in leaves of Scindapsus

At room temperature, we studied the delayed luminescence characteristic curves of the leaves of Scindapsus in darkroom and continuously irradiate at different wavelengths. The results show that the decay of stimulated emission photons induced by pulsed laser has a typical hyperbolic trend with the delay time, and the goodness of fitted curve can reach 99.9%. The initial photon intensity I (0) and decay time τ are closely related to the environment and physiological activities of plants. In the dark room, it was found that the initial intensity and decay time of the delayed luminescence curve for picked leaves decreased, while the potted leaves remained almost unchanged. The characteristic curve of laser-induced delayed luminescence accurately reflected the process and degree of plant wilting. For continuously irradiated by the laser wavelength of 520 nm and 400 nm, respectively, the change in curve parameters reflects the selective absorption of different light wavelengths. Compare the condition with having light and without, the metabolites of photosynthesis and respiration are different in plants, which leads to greatly changes in decay time. The characteristic curve of laser-induced delayed luminescence can be used as an important parameter to measure the physiological state of plants.

Smart meta-superconductor MgB2 constructed by the dopant phase of luminescent nanocomposite

On the basis of the idea that the injecting energy will improve the conditions for the formation of Cooper pairs, a smart meta-superconductor (SMSC) was prepared by doping luminescent nanocomposite Y2O3:Eu3+/Ag in MgB2. To improve the superconducting transition temperature (TC) of the MgB2-based superconductor, two types of Y2O3:Eu3+/Ag, which has the strong luminescence characteristic, with different sizes were prepared and marked as m-Y2O3:Eu3+/Ag and n-Y2O3:Eu3+/Ag. MgB2 SMSC was prepared through an ex situ process. Results show that when the dopant content was fixed at 2.0 wt.%, the TC of MgB2 SMSC increased initially then decreased with the increase in the Ag content in the dopant. When the Ag content is 5%, the TC of MgB2 SMSC was 37.2–38.0 K, which was similar to that of pure MgB2. Meanwhile, the TC of MgB2 SMSC doped with n-Y2O3:Eu3+/Ag increased initially then decreased basically with the increase in the content of n-Y2O3:Eu3+/Ag, in which the Ag content is fixed at 5%. The TC of MgB2 SMSC doped with 0.5 wt.% n-Y2O3:Eu3+/Ag was 37.6–38.4 K, which was 0.4 K higher than that of pure MgB2. It is thought that the doping luminescent nanocomposite into the superconductor is a new means to improve the TC of SMSC.

Optimization of Tb3+/Gd3+ Molar Ratio for Rapid Detection of Naja Atra Cobra Venom by Immunoglobulin G-Conjugated GdPO4·nH2O : Tb3+ Nanorods

In this report, GdPO4·nH2O and Tb3+-doped GdPO4·nH2O nanorods@silica-NH2 conjugated with IgG antibody were synthesized by applying hydrothermal, sol-gel, and coprecipitation methods successively. The effects of Tb3+/Gd3+ molar ratios of reactants on the size, morphology, and luminescence of the synthesized samples were also investigated. For the optimized GdPO4·nH2O : Tb3+ sample, uniform nanorods sizing from 10 to 30 nm in diameter and from 200 to 300 nm in length were obtained with the strongest luminescence in green color with narrow bands under the UV excitation (325 nm). The results revealed that, after being coated with silica-NH2 and conjugated with IgG antibody, all luminescence characteristic peaks of GdPO4·nH2O : Tb3+ corresponding to the process of energy transfer from Gd3+ to Tb3+ and then the emission from 5D4 → 7FJ (J=6,5,4,3) of Tb3+ were still clearly observed. The initial results of using the optimized Tb3+-doped GdPO4·nH2O nanorods@silica-NH2 conjugated with IgG antibody for rapid selective detection of Naja atra cobra venom were also reported.