Enhanced Fluorescence Characteristics of SrAl2O4: Eu2+, Dy3+ Phosphor by Co-Doping Gd3+ and Anti-Counterfeiting Application.

A series of long-afterglow luminescent materials (SrAl2O4: Eu2+ (SAOE), SrAl2O4: Eu2+, Dy3+ (SAOED) and SrAl2O4: Eu2+, Dy3+, Gd3+ (SAOEDG)) was synthesized via the combustion method. Temperature and concentration control experiments were conducted on these materials to determine the optimal reaction temperature and ion doping concentration for each sample. The crystal structure and luminescent properties were analyzed via X-ray diffraction (XRD), photoluminescence (PL), and afterglow attenuation curves. The outcomes demonstrate that the kind of crystal structure and the location of the emission peak were unaffected by the addition of ions. The addition of Eu2+ to the matrix's lattice caused a broad green emission with a central wavelength of 508 nm, which was attributed to the characteristic 4f65d1 to 4f7 electronic dipole, which allowed the transition of Eu2+ ions. While acting as sensitizers, Dy3+ and Gd3+ could produce holes to create a trap energy level, which served as an electron trap center to catch some of the electrons produced by the excitation of Eu2+ but did not itself emit light. After excitation ceased, this allowed them to gently transition to the ground state to produce long-afterglow luminescence. It was observed that with the addition of sensitizer ions, the luminous intensity of the sample increased, and the afterglow duration lengthened. The elemental structure and valence states of the doped ions were determined with an X-ray photoelectron spectrometer (XPS). Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) were used to characterize the samples. The results show that the sample was synthesized successfully, and the type and content of ions in the fluorescent powder could be determined. The fluorescence lifetime, quantum yield, bandgap value, afterglow decay time, and coordinate position in the coherent infrared energy (CIE) diagram of the three best sample groups were then analyzed and compared. Combining the prepared phosphor with ink provides a new idea and method for the field of anti-counterfeiting through screen printing.

Influence of Carboxymethyl Cellulose on the Stability, Rheological Property, and in-vitro Digestion of Soy Protein Isolate (SPI)-Stabilized Rice Bran Oil Emulsion.

In this study, carboxymethyl cellulose (CMC) was added to soybean protein isolate (SPI)-stabilized rice bran oil (RBO) emulsion to improve its physicochemical stability and free fatty acid (FFA) release characteristics. RBO emulsions stabilized by SPI and various contents of CMC were prepared and assessed by measuring zeta potential, particle size, transmission, and microstructure, the rheological properties were analyzed by dynamic shear rheometer. In addition, its chemical stability was characterized by a storage experiment, and the FFA release was explored by a simulated gastrointestinal tract (GIT) model. It showed that the negative charge of the droplets of RBO emulsion was increased with increasing CMC content. The decrease in transmission of SPI-stabilized RBO emulsion with increasing CMC content was due to the droplets not being free to move by the special network interaction and an increase in the viscosity. According to the determination of the reactive substances of lipid hydroperoxide and thiobarbituric acid during 30 days storage at 37°C, the chemical stability of the emulsion added with CMC was enhanced compared with the SPI-stabilized RBO emulsion. In-vitro digestion studies not only evaluated the structural changes of RBO emulsions at different stages, but also found that RBO emulsion with CMC showed a higher level of free fatty acids release in comparison with that without CMC. It indicated that the utilization of CMC can improve the bioavailability of RBO emulsions.

[Study on crystalline and properties of N', N-Bis (n-butyl)-3, 4, 9, 10-perylene tetracarboxylic diimide].

N', N-Bis(n-butyl)-3,4,9,10-perylene tetracarboxylic diimide was synthesized, purified and crystallized, then IR, element analysis and X-ray diffraction were tested. The spectrum of UV-Vis absorption (maximum absorption peak at 524. 80 nm), fluorescence emission (maximum emission intensity at 539.0 nm) and stokes displacement (15 nm) of the compound in DMF were analyzed. The UV-Vis absorption spectrum between 400 and 700 nm in a film can indicate that alpha-crystal has much stronger absorption peaks than beta-crystal and that red shift of maximum absorption occurs (545 to 580 nm) when beta-crystal is changed into alpha-crystal. It is obvious that CPS of alpha, beta-crystal are respectively 2 508 at 26.0 degrees and 1 891 at 25.2 degrees in the X-ray diffraction pattern. The functional separate photoreceptors of alpha, beta-crystal as charge generation material were made, and photoconductivity properties were tested after charging the sample and then using spectral light of 532 nm formed by a band path filter.