Nanocarbon-supported Pt nanoparticles (NPs) were prepared and tested for the propane dehydrogenation reaction (PDH). The nanocarbon support is composed of a nanodiamond core and a defective, ultrathin graphene nanoshell (ND@G). The Pt/ND@G catalyst experienced slight deactivation during the 100 h PDH test, while the Pt/Al 2 O 3 catalyst showed severe deactivation after the 20 h PDH test. Pt NPs exhibited superior sintering resistance versus that of the ND@G support. This particular support structure of ND@G allows electrons on the defects to transfer to the Pt NPs, leading to a strong metal−support interaction, which significantly prevents Pt NP sintering and promotes the desorption of electron-rich propylene. This electron transfer mechanism was also confirmed by a CO catalytic oxidation test.
The development of new-type memristors with special performance is of great interest. Herein, an inorganicorganic hybrid crystalline polyoxometalate (POM) with usual dynamic structures is reported and used as active material for fabricating memristor with unique temperature-regulated resistive switching behaviors. The hybrid POM not only exhibits tunable thermochromic properties, but also thermalinduced reversible aggregation and disaggregation reactions, leading to reversible structural transformations in SCSC fashion. Further, the memory device using the hybrid POM as active layer exhibits uncommon performance, which can keep resistive switching silent in the low temperature range of 30-150 8C, but show nonvolatile memory behavior in the high temperature range of 150-270 8C. Particularly, the silent and working states at three special temperatures (30, 150 and 270 8C) can be monitored by chromism. The correlation between structure and resistive switching property of the material has been discussed. The work demonstrates that crystalline inorganic-organic hybrid POMs are promising materials for making memristors with superior performance.Memristors are leading candidates for the next generation non-volatile memory devices owing to their low power consumption, high access speed, multi-state switching and device scalability. [1][2][3][4][5][6][7] The development of memristors with high performance and reliability under special/harsh environments is in great demand so that they can be applied in many promising fields, such as aerospace, geothermal, oil and gas industries. [8] In the past few decades, great efforts have been paid to improve the switching performance of memristors at high temperatures because the working mechanisms of memory devices, including filamentary conduction, space charge trapping, valence and conformation changes and
D-Allulose is considered an ideal alternative to sucrose and has shown tremendous application potential in many fields. Recently, most efforts on production of D-allulose have focused on in vitro enzyme-catalyzed epimerization of cheap hexoses. Here, we proposed an approach to efficiently produce D-allulose through fermentation using metabolically engineered Escherichia coli JM109 (DE3), in which a SecY (ΔP) channel and a D-allulose 3-epimerase (DPEase) were co-expressed, ensuring that D-fructose could be transported in its nonphosphorylated form and then converted into D-allulose by cells. Further deletion of f ruA, manXYZ, mak, galE, and f ruK and the use of Ni 2+ in a medium limited the carbon flux flowing into the byproduct-generating pathways and the Embden−Meyerhof−Parnas (EMP) pathway, achieving a ≈ 0.95 g/g yield of D-allulose on D-fructose using E. coli (DPEase, SecY [ΔP], ΔFruA, ΔManXYZ, ΔMak, ΔGalE, ΔFruK) and 8 μM Ni 2+ . In fed-batch fermentation, the titer of D-allulose reached ≈23.3 g/L.
A copper-mediated trifluoromethylthiolation of vinyl bromides has been developed. This method provides ready access to vinyl trifluoromethyl thioethers in good to high yields from simple, inexpensive starting materials. A broad substrate scope is achieved, and the reaction is compatible with various functional groups, including cyano, nitro, trifluoromethyl, alkoxy, amino, halide, and heterocyclic groups.
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.