Preparative separation and purification of rebaudioside A from steviol glycosides using mixed-mode macroporous adsorption resins (MARs) were systematically investigated. Mixed-mode MARs were prepared by a physical blending method. By evaluation of the adsorption/desorption ratio and adsorption/desorption capacity of mixed-mode MARs with different proportions toward RA and ST, the mixed-mode MAR 18 was chosen as the optimum strategy. On the basis of the static tests, it was found that the experimental data fitted best to the pseudosecond-order kinetics and Temkin-Pyzhev isotherm. Furthermore, the dynamic adsorption/desorption experiments were performed on the mini column packed with mixed-mode MAR 18. After one run treatment, the purity of rebaudioside A in purified product increased from 40.77 to 60.53%, with a yield rate of 38.73% (W/W), and that in residual product decreased from 40.77 to 36.17%, with a recovery yield of 57.61% (W/W). The total recovery yield reached 96.34% (W/W). The results showed that this method could be utilized in large-scale production of rebaudioside A from steviol glycosides in industry.

According to the Friedel-Crafts and amination reaction, a series of macroporous adsorption resins (MARs) with novel structures were synthesized and identified by the Brunauer-Emmett-Teller (BET) method and Fourier transform infrared (FTIR) spectra, and corresponding adsorption behaviors for (-)-epigallocatechin gallate (EGCG) and caffeine (CAF) extracted from waste tea were systemically investigated. Based on evaluation of adsorption kinetics, the kinetic data were well fitted by pseudo-second-order kinetics. Langmuir, Freundlich, Temkin-Pyzhev, and Dubinin-Radushkevich isotherms were selected to illustrate the adsorption process of EGCG and CAF on the MARs. Thermodynamic parameters were adopted to explain in-depth information of inherent energetic changes associated with the adsorption process. The effect of temperature on EGCG and CAF adsorption by D101-3 was further expounded. Van der Waals force, hydrogen bonding, and electrostatic interaction were the main driving forces for the adsorption of EGCG and CAF on the MARs. This study might provide a scientific reference point to aid the industrial large-scale separation and enrichment of EGCG from the extracts of waste tea using modified MARs.

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Red or near-infrared phosphors, which have a lower absorption in biological tissue, show excellent promise in the field of bioimaging. Here, we design the red phosphor with a broad emission band and realize tunable luminescence of Cr3+ by two methods, i.e., adjusting the Cr3+-doping concentration in Zn3(AlGa)2­Ge2O10 solid solution and doping In3+ ions in Zn3Al2Ge2O10 due to a size mismatch. The solid solution is illustrated by density functional theory calculation, X-ray powder diffraction, and high resolution transmission electron microscopy. The Cr3+-doped phosphor shows a red emission band centered at 705 nm, which is ascribed to the 2E → 4A2 and 4T2(4F) → 4A2 transitions. When Cr3+ ions or In3+ ions are introduced, the full width at half-maximum (fwhm) increased due to the combination of crystal field splitting, nephelauxetic effect, and reabsorption.

Lead halide perovskites and their applications in the optoelectronic field have garnered intensive interest over the years. Inorganic perovskites (IHP), though a novel class of material, are considered as one of the most promising optoelectronic materials. These materials are widely used in detectors, solar cells, and other devices, owing to their excellent charge‐transport properties, high defect tolerance, composition‐ and size‐dependent luminescence, narrow emission, and high photoluminescence quantum yield. In recent years, numerous encouraging achievements have been realized, especially in the research of CsPbX3 (X = Cl, Br, I) nanocrystals (NCs) and surface engineering. Therefore, it is necessary to summarize the principles and effects of these surface engineering optimization methods. It is also important to scientifically guide the applications and promote the development of perovskites more efficiently. Herein, the principles of surface ligands are reviewed, and various surface treatment methods used in CsPbX3 NCs as well as quantum‐dot light‐emitting diodes are presented. Finally, a brief outlook on CsPbX3 NC surface engineering is offered, illustrating the present challenges and the direction in which future investigations are intended to obtain high‐quality CsPbX3 NCs that can be utilized in more applications.

A series of LiBaBO3:RE (RE=Eu 2+ /Tb 3+ /Eu 3+ ) phosphors had been synthesized by the high-temperature solid-state reaction method. The X-ray diffraction (XRD), emission spectra, excitation spectra, decay lifetimes, and diffuse reflection spectra were utilized to characterize the phosphors. The as-prepared samples had been demonstrated via XRD measurement and showed that the Eu 2+ /Tb 3+ /Eu 3+ can be efficiently doped into the host. The obtained phosphors can emit different colors light when doping with different activators. The energy transfer from Tb 3+ to Eu 3+ occurs in LiBaBO3:0.03Eu 3+ , yTb 3+ prepared in the air. While an abnormal reduction phenomenon was reported when Eu and Tb ions were co-doped in LiBaBO3 and prepared in an inferior reductive atmosphere, which showed tunable-color from blue to red based on energy transfer of Eu 2+ →Tb 3+ →Eu 3+ ions. And the energy transfer not only can occur between Eu 2+ and Tb 3+ ions, but also Tb 3+ and Eu 3+ ions. All these results reveal that Tb 3+ can play the role of storing the energy for Eu 3+ , and LiBaBO3 may be potential candidate phosphors for LEDs.

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