Ten compounds, including a new guaiane-type sesquiterpene lactone, were isolated from the aerial parts of . The structure of the new compound was determined to be 5-hydroxyguaia-3(4),11(13),10(14)-trien-6α,12-olide, named scoparanolide. Six known sesquiterpene lactones [estafiatone, 3β,4α-dihydroxyguaia-11(13),10(14)-dien-6α,12-olide, estafiatin, preeupatundin, 3β-hydroxycostunolide, and ludovicin B] and three known coumarin derivatives (scopoletin, scoparone, and isofraxidin) were identified by nuclear magnetic resonance and electrospray ionization mass spectroscopy. Six known sesquiterpene lactones were found for the first time in this plant. The angiotensin I-converting enzyme inhibitory activities of coumarin derivatives and scopoletins were significantly higher compared to those of sesquiterpene lactones and quercetin.
Lead‐free 0.77(Bi0.5Na0.5)TiO3–0.23Sr(Ti1−xFex)O3 (x = 0, 0.04) (BNT–23STFx) was prepared using a conventional solid‐state reaction route. The effects of Fe‐modification on the chemical homogeneity from a μm scale perspective, the core‐shell domains structures, and the ferroelectric properties were investigated. The chemical homogeneity was analyzed using energy dispersive X‐ray mapping in scanning transmission electron microscopy mode, and the field‐dependent behaviors of strain and polarization were obtained to determine the ferroelectric properties. Substituting Fe3+ for Ti4+ resulted in completely different electrical behavior and properties, despite similar XRD patterns and microstructures. The Fe‐substitution promoted the mobility of Sr2+ ions in the BNT phase and, as a consequence, the chemical homogeneity increased and the core‐domains collapsed. Extending the ceramic processing, such as milling time and sintering time, affected domain distribution and compositional inhomogeneity, which led to a gradual transformation from ferroelectric to relaxor.
A new plasma-assisted electrolysis method has been developed to synthesize amorphous TiO 2 nanoparticles and exploited for the enhanced photocatalytic performance. The method is simple, environmentally friendly, produces nanoparticles directly from bulk metal, and is suitable for mass production. The process was conducted in low-concentration nitric acid electrolyte under a voltage of 450 V, the minimum necessary to produce plasma on the anode surface. The average nanoparticle size was tuned between 16 and 28 nm by controlling electrolyte concentration within the range of 5 to 15 mM. The production rate increased with time, with the maximum of 11.27 g/h. The amorphous TiO 2 nanoparticles were calcined at various temperatures to determine the crystalline structures and to compare their photocatalytic effects. The structure ranged from pure anatase to rutile under various calcination temperatures; the anatase-rutile mixed phase produced at 600 • C showed the highest catalytic performance, with 94% degradation of methylene blue within 30 min owing to a synergetic effect between the phases. This liquid-phase plasma-assisted electrolysis method can pave the way for large-scale synthesis of highly pure metal-based ceramic nanoparticles with narrow size distributions. Titanium dioxide is a semiconducting material that shows chemical stability and noble characteristics. For several decades, it has been extensively studied due to its physical and chemical properties such as wide band gap and efficient photon electron transfer, which allow its application in photocatalysis, 1-3 antireflection coating, 4-6 water splitting, 7-9 and dye-sensitized solar cells. 10-13 Among these, its photocatalytic effect has attracted the most attention; TiO 2 possesses powerful organic decomposition properties under ultraviolet light.Formation of the three main crystal phases of TiO 2 , namely anatase, rutile, and brookite, depends on the synthesis method and calcination conditions. Generally, mixed phases of anatase and rutile show the best photocatalyst performance due to a synergistic effect. Among the pure phases, anatase yields more efficient catalytic performance than rutile because it has a larger band gap (anatase 3.2 eV, rutile 3.0 eV). The wider band gap reduces light absorption and raises the maximum of the valence band to a higher level that is closer to adsorbed molecules' redox potentials. Then, it facilitates electron transfer from the TiO 2 surface to molecules due to the increased oxidation potential of the electrons. This enhances the decomposition of organic molecules absorbed on the surface of the TiO 2 .14 The photocatalytic performance originating from absorbed ultraviolet light is also affected by photogenerated charge carriers such as electrons and holes. 15 Highly excited holes in the valence band diffuse into the outer layer of a particle and react with adsorbed water molecules on the surface, creating reactive •OH radicals. In addition, electrons remaining in the conduction band produce oxide radicals on the parti...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.