Recent Research Progress of Mn4+-Doped A2MF6 (A = Li, Na, K, Cs, or Rb; M = Si, Ti, Ge, or Sn) Red Phosphors Based on a Core–Shell Structure

White light emitting diodes (WLEDs) are widely used due to their advantages of high efficiency, low electricity consumption, long service life, quick response time, environmental protection, and so on. The addition of red phosphor is beneficial to further improve the quality of WLEDs. The search for novel red phosphors has focused mainly on Eu2+ ion- and Mn4+ ion-doped compounds. Both of them have emissions in the red region, absorption in blue region, and similar quantum yields. Eu2+-doped phosphors possess a rather broad-band emission with a tail in the deep red spectral range, where the sensitivity of the human eye is significantly reduced, resulting in a decrease in luminous efficacy of WLEDs. Mn4+ ions provide a narrow emission band ~670 nm in oxide hosts, which is still almost unrecognizable to the human eye. Mn4+-doped fluoride phosphors have become one of the research hotspots in recent years due to their excellent fluorescent properties, thermal stability, and low cost. They possess broad absorption in the blue region, and a series of narrow red emission bands at around 630 nm, which are suitable to serve as red emitting components of WLEDs. However, the problem of easy hydrolysis in humid environments limits their application. Recent studies have shown that constructing a core–shell structure can effectively improve the water resistance of Mn4+-doped fluorides. This paper outlines the research progress of Mn4+-doped fluoride A2MF6 (A = Li, Na, K, Cs, or Rb; M = Si, Ti, Ge or Sn), which has been based on the core–shell structure in recent years. From the viewpoint of the core–shell structure, this paper mainly emphasizes the shell layer classification, synthesis methods, luminescent mechanism, the effect on luminescent properties, and water resistance, and it also gives some applications in terms of WLEDs. Moreover, it proposes challenges and developments in the future

Deoxidation thermodynamics of Ti–O in hydrogen atmosphere: Preparation of TiH2 alloy powder by direct reduction of spent V2O5–WO3/TiO2 catalyst with magnesiothermic

The abundant metal Ti is a high-quality metal with lightweight, high strength, and corrosion resistance. However, due to its harsh preparation conditions, the price remains high, so titanium metal's simple and effective products have become a challenge for the world's scientific research community. In this paper, by calculating the oxygen potential of Ti–O, Ti–H, and Ti–H–O solid solutions, the oxygen potential of Ti–H–O was obtained when the oxygen content was 0.03 and 0.009. As H2 enters the Ti–O lattice, the oxygen potential of the Ti–H–O system increases with the increase of H content. Thermodynamic calculations showed that introducing hydrogen effectively destroyed the stability of Ti–O solid solutions. At the same time, this paper uses a magnesiothermic as a reducing agent. To verify the feasibility of the above thermodynamics, reduce the spent V2O5–WO3/TiO2 catalyst (Ti > 80 wt%) of titanium-rich materials in a hydrogen atmosphere. Finally, the spent V2O5–WO3/TiO2 catalyst was reduced at 750 °C for 8–24 h to obtain TiH2 powder with an oxygen content of 0.9 wt%

Network Pharmacology and Molecular Docking Analysis on Molecular Targets and Mechanisms of Buyang Huanwu Decoction in the Treatment of Ischemic Stroke

Background and Objective. With the exact clinical efficacy, Buyang Huanwu decoction (BHD) is a classical prescription for the treatment of ischemic stroke (IS). Here, we aimed to investigate the pharmacological mechanisms of BHD in treating IS using systems biology approaches. Methods. The bioactive components and potential targets of BHD were screened by TCMSP, BATMAN-TCM, ETCM, and SymMap databases. Besides, compounds that failed to find the targets from the above databases were predicted through STITCH, SwissTargetPrediction, and SEA. Moreover, six databases were searched to mine targets of IS. The intersection targets were obtained and analyzed by GO and KEGG enrichment. Furthermore, BHD-IS PPI network, compound-target network, and herb-target-pathway network were constructed by Cytoscape 3.6.0. Finally, AutoDock was used for molecular docking verification. Results. A total of 235 putative targets were obtained from 59 active compounds in BHD. Among them, 62 targets were related to IS. PPI network showed that the top ten key targets were IL6, TNF, VEGFA, AKT1, etc. The enrichment analysis demonstrated candidate BHD targets were more frequently involved in TNF, PI3K-Akt, and NF-kappa B signaling pathway. Network topology analysis showed that Radix Astragali was the main herb in BHD, and the key components were quercetin, beta-sitosterol, kaempferol, stigmasterol, etc. The results of molecular docking showed the active components in BHD had a good binding ability with the key targets. Conclusions. Our study demonstrated that BHD exerted the effect of treating IS by regulating multitargets and multichannels with multicomponents through the method of network pharmacology and molecular docking

Influences of sintering temperature on pore morphology, porosity, and mechanical behavior of porous Ti

The purpose of this study was to determine the influences of the sintering temperature on the pore morphology, porosity, and mechanical behavior of titanium foams. Porous Ti samples were successfully manufactured using the metal powder metallurgy method in conjunction with sintering at the four temperatures (900, 1000, 1100, and 1200 °C). The sintering temperature significantly influenced the pore morphology, porosity, and mechanical behavior of the titanium foams. The titanium foams were characterized using an optical microscope in conjunction with scanning electron microscopy. A fracture showed the appearance and growth of a sintering neck between adjacent particles. As the sintering temperature increased, the sintering necks gradually became clearer. The porosity decreased from 56.48% to 46.83% as the sintering temperature increased from 900 °C to 1200 °C, while the initial yield strength of the porous titanium increased from 101.81 to 208.01 MPa. The porous titanium foams produced by the metal powder metallurgy method have a significant utilization potential in hard-tissue engineering

Tuning Interfacial Magnetic Ordering via Polarization Control in Ferroelectric SrTiO₃/PbTiO₃ Heterostructure

The electromagnetic properties at the interface of heterostructure are sensitive to the interfacial crystal structure and external field. For example, the two-dimensional magnetic states at the interface of LaAlO₃/SrTiO₃ are discovered and can further be controlled by electric field. Here, we study two types of heterostructures, TiO₂/PbTiO₃ and SrTiO₃/PbTiO₃, using first-principle electronic structure calculations. We find that the ferroelectric polarization discontinuity at the interface leads to partially occupied Ti 3d states and the magnetic moments. The magnitude of the magnetic moments and the ground-state magnetic coupling are sensitive to the polarization intensity of PbTiO₃. As the ferroelectric polarization of PbTiO₃ increases, the two heterostructures show different magnetic ordering that strongly depends on the electron occupation of the Ti t_2g orbitals. For the TiO₂/PbTiO₃ interface, the magnetic moments are mostly contributed by degenerated d<i>_yz</i>/d<i>_xz</i> orbitals of interfacial Ti atoms and the neighboring interfacial Ti atoms form ferromagnetic coupling. For SrTiO₃/PbTiO₃ interface, the interfacial magnetic moments are mainly contributed by occupied d_<i>xy</i> orbital because of the increased polarization intensity, and as the electron occupation increases, there exists a transition of the magnetic coupling between neighboring Ti atoms from ferromagnetism to antiferromagnetism via the superexchange interaction. Our study suggests that manipulating the polarization intensity is one effective way to control interfacial magnetic ordering in the perovskite oxide heterostructures