ABSTRACT
The liquid micro-environment plays a momentous role in the regulation of various activities, and the abnormal changes are often closely related to the deterioration phenomena in multiple beverages. The local viscosity fluctuation has long been regarded as a key indicator to reflect the micro-environmental status changes. Herein, we proposed a versatile optical sensor, rosmarinic acid (RA), one kind of green natural product extracted from rosemary, for monitoring liquid micro-environmental viscosity alterations. RA displays a larger Stokes shift (123.8 nm) with narrow-band energy and exhibits wide adaptability, high selectivity, good sensitivity, and excellent photostability in various commercial liquids. When in high viscous media, a bright fluorescent signal of RA is specifically activated, and a high signal-to-noise ratio signal was released (58-fold). With the assistance of the fluorescence analytical technique, we have successfully achieved tracking the viscosity fluctuations during the deterioration stage of liquids via an in situ and visualization method. Our study will spur additional research on the molecular tools extracted from natural products for liquid safety inspection, and a convenient and sustainable application pathway has been established.
Subject(s)
Rosmarinus , Fluorescence , Viscosity , Lipids/chemistry , Rosmarinic AcidABSTRACT
The morphological and structural optimizations of electrode materials are efficient ways to enhance their electrochemical performance. Herein, we report a facile co-precipitation and subsequent calcination method to fabricate Li1.2Mn0.54Ni0.13Co0.13O2 nanosheets consisting of interconnected primary nanoparticles and open holes through the full thickness. By comparing the nanosheets and the agglomerated nanoparticles, the effects of the morphology and structure on the electrochemical performance are investigated. Specifically, the nanosheets exhibit a discharge capacity of 210 mA h g-1 at 0.5C with a capacity retention of 85% after 100 cycles. The improved electrochemical performance could be attributed to their morphological and structural improvements, which may facilitate sufficient electrolyte contacts, short diffusion paths and good structural integrity during the charge/discharge process. This work provides a feasible approach to fabricate lithium-rich layered oxide cathode materials with 2D morphology and porous structure, and reveals the relationships between their morphology, structure and electrochemical performance.
ABSTRACT
Polycrystalline Ba3La2(BO3)4:Ce3+,Dy3+ sub-micrometer-sized phosphors were synthesized by solid-state reaction under a weak reductive atmosphere. The structure, static and time-resolved photoluminescence are investigated. Under the near-ultraviolet excitation, the Ba3La2(BO3)4:Dy3+ phosphors emit white light with three intense emission bands centered at 483, 575, and 665â¯nm. The efficient energy transfer from Ce3+ to Dy3+ in Ba3La2(BO3)4 phosphor was found by excitation/emission spectra and decay time measurements, and the resonant type was demonstrated by a dipole-dipole mechanism. A tunable emission hue from blue (0.18, 0.20) to blue-white (0.26, 0.29) and eventually to white (0.32, 0.33) was obtained in Ba3La2(BO3)4:Ce3+,Dy3+ phosphors. Owing to the broad UV excitation band, indicating that Ba3La2(BO3)4:Ce3+,Dy3+ phosphors can be considered as a potential candidate for ultraviolet-based white light-emitting diodes.
ABSTRACT
Irregular club-shape nanoparticles of Yb3+ doped Y3Al5O12 were synthesized by the co-precipitation method using different precipitator, such as ammonium hydrogen carbonate, hexamethylene tetramine and urea. The reaction mechanism of different precipitator and the effect on the particle size and dispersion of Y3Al5O12:Yb3+ powders were investigated, and the influence of ammonium sulfate as the dispersant in the reaction system was also discussed. The results show that the large and agglomerated Y3Al5O12:Yb3+ powders were obtained from urea compared to that uniform particle size and dispersion one from ammonium hydrogen carbonate and hexamethylene tetramine. Moreover, ammonium sulfate is beneficial to enhance the dispersion of the particles for ammonium hydrogen carbonate and to form the club-shape morphology of Y3Al5O12:Yb3+ crystals for hexamethylene tetramine. The photoluminescence property investigation shows that the near-infrared emission intensity of the powders increased with the calcining temperature as well as the particle size and dispersion of as-prepared particles for all the precipitators.
ABSTRACT
Submicron core-shell structure particles SiO2@Y3Al5O12:Er3+, which silica spherical particles was coated with an yttrium aluminum garnet (Y3Al5O12) layer doped with Er3+, were prepared by the modified Pechini-Type sol-gel method for the first time. The structure and morphology of samples were detected by the X-ray powder diffraction (XRD) measurement, field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM), respectively. The results indicate that well-crystallized garnet nanocrystallines were formed on the surface of the silica particles. The luminescent spectra in near infrared and visible region of the core-shell structured SiO2@Y3Al5O12:Er3+ powders were also investigated and compared with those of the pure Y3Al5O12:Er3+ and the Er3+ doped silicate glass. The results show that mono-dispersed SiO2@Y3Al5O12:Er3+ core-shell spherical particles with the near infrared, red and green luminescent emissions under the excitation of 980 nm laser diode have been successfully synthesized.
