Search

Chemistry laboratory training is an integral part of chemistry teaching. However, outdated experimental protocols present limitations and can hinder students’ initiative and innate inclination toward exploration. In this study, novel scientific concepts were translated into experimental chemistry teaching. Small fluorescent molecules with aggregation-induced emission and excited-state intramolecular proton transfer properties were prepared using a carbonyl nucleophile addition reaction. The basic photophysical properties of the molecules and their fluorescence response to acid-base stimulation were evaluated experimentally. The non-toxic and non-noxious reagents used for the experiments were refluxed in ethanol for 0.5 h to implement green organic synthesis principles. The experiment was compact and the fluorescence and color changes of the as-synthesized molecules were conspicuous and remarkable. This can stimulate students’ enthusiasm for experimental chemistry. In addition to the basic organic synthesis reaction, this experiment included several modern analysis and characterization methods, such as nuclear magnetic resonance, Fourier-transform infrared spectroscopy, ultraviolet-visible absorption spectroscopy, and fluorescence spectroscopy. We are confident that this intuitive and effective basic experiment can effectively stimulate and cultivate the innate curiosity of students. [ABSTRACT FROM AUTHOR]

One of the most effective methods for improving the storage density of resistive random access memories (RRAMs) is to fabricate 3D vertical stacking devices. By using BP-DDAT(DDAT: S-1-dodecyl-S ′-(α,α′-dimethyl-α′ ′- aceticacid)trithiocarbonate) as a key 2D template and reversible addition-fragmentation chain transfer (RAFT) reagent, a novel poly(N-vinylcarbazole) covalently functionalized black phosphorus derivative (BP-PVK) is successfully synthesized and well-characterized by infrared spectroscopy, X-ray electron spectroscopy and UV-Vis absorption spectroscopy. The environmental stability and solubility of BP nanosheets are greatly improved. Using BP-PVK as active layer, a double-layer vertically stacked RRAM memory device (17×17 stripe array) with a configuration of Al/BP-PVK/Al/BP-PVK/Al is fabricated. The as-fabricated device shows good bistable electrical switching and non-volatile rewritable performance at room temperature, with an ON/OFF current ratio exceeding 10³, higher production yield of the memory devices and structural uniformity. [ABSTRACT FROM AUTHOR]

BACKGROUND: There are differences in the production characteristics, chemical composition, coloration mechanism and formation conditions of green tourmaline from different producing areas. At present, the mineral species and coloration mechanism of Tanzanian green tourmaline have not been solved, which makes it difficult for its scientific identification and quality rating. OBJECTIVES: To study the mineralogical characteristics and coloration mechanism of Tanzanian green tourmaline. METHODS: The mineral component was analyzed by infrared spectroscopy and Raman spectroscopy. Microtexture was characterized by polarized light microscopy. Electron probe microanalyzer, and ultraviolet-visible (UV-Vis) spectroscopy were applied to analyze the chemical composition. RESULTS: The main mineral component of tourmaline in Tanzania was MgO tourmaline, which was characterized by single crystal, small grain, no cleavage, and split development, and can be used as a gemstone. The main chemical component of green tourmaline was SiO2, Al2O3, MgO and B2O3, with average contents of 37.52%, 36.26%, 9.65% and 8.42%, respectively. In addition, it contained a small amount of FeO, Cr2O3 and TiO2. Combined with the absorption spectrum in the ultraviolet region of 440 nm, 600 nm and 680 nm in UV-Vis spectroscopy, it was concluded that the tiny amounts of Cr3+ replacing Al3+ into the crystal lattice was the main cause of the green color. CONCLUSIONS: The mineralogical characteristics and coloration mechanism of green tourmaline in Tanzania was confirmed, which provides a theoretical basis for the scientific identification, further quality evaluation and utilization. [ABSTRACT FROM AUTHOR]