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In this article, a hitherto unreported catalyst-free ring expansion reaction of tetrahydroisoquinolines with o-alkynylarylaldehydes for the construction of the dibenzo[b,d]azepine skeleton is described. Using air as a "green" oxidant, some important biologically active dibenzo[b,d]azepines were produced with favorable functional group tolerance and a wide substrate scope. The synthetic potential was further confirmed by facile scale-up reactions and the synthesis of isoindoline derivatives. [ABSTRACT FROM AUTHOR]

The strength of backfill is greatly influenced by its inclination angle and interlayer concentration. in order to study the influence of inclination angle and interlayer mass concentration on the strength of backfill, a group of layered cemented backfill with cement-sand ratio of 1:4, interlayer mass concentration of 66%, 67% and 68% and inclination angles of 0°, 10°, 20° and 30° were prepared by using tailings as aggregate. The uniaxial compression test was carried out to analyse the effect of interlayer mass concentration and inclination angle on layered cemented backfill. The crack propagation and energy change law of the specimen during compression were analysed by J-integral and energy conservation law. The relationship between the crack initiation and propagation and strain energy of two representative threelayer backfill specimens was analysed by numerical modelling. The results show that the increase in the layer number and the inclination angle of the backfill can weaken the strength of the backfill. In a certain range of inclination angles, the weakening coefficient of the backfill caused by the inclination angle is very consistent with the cosine value of the corresponding angle. Due to the release of crack energy and the existence of interface J integral, the uniaxial compressive strength of different mass concentration backfill is different at various positions. When the displacement reaches a certain value, the crack and strain energy no longer increase. [ABSTRACT FROM AUTHOR]

We report a novel scanning probe electron energy spectrometer (SPEES) which combines a double toroidal analyzer with a scanning tunneling microscope to achieve both topography imaging and electron energy spectroscopy mapping of surface in situ. The spatial resolution of spectroscopy mapping is determined to be better than 0.7 ± 0.2 μm at a tip sample distance of 7 μm. Meanwhile, the size of the field emission electron beam spot on the surface is also measured, and is about 3.6 ± 0.8 μm in diameter. This unambiguously demonstrates that the spatial resolution of SPEES technique can be much better than the size of the incident electron beam. Published by AIP Publishing. [ABSTRACT FROM AUTHOR]