A universal KOH-free strategy is developed to prepare nitrogen-doped carbon nanosheets (N-SCNSs) derived from edible oil residues with high specific surface area and high nitrogen content for application in high-rate and high-energy supercapacitors.

A wavelength splitter and a polarization splitter with high compactness and extremely simple structures are designed for optical communication wavelengths. Operation principle of the devices is based on directional coupling in two parallel periodic dielectric waveguides. The device performances have been evaluated by the finite-difference time-domain simulations. The wavelength splitter with a coupling region length of 5 mum can route 1.31 and 1.55 mum wavelengths to corresponding outputs with a transmittance of more than 93%, while the polarization splitter with a coupling region length of 4.6 mum can divide lightwaves in TM and TE polarizations with a degree of polarization higher than 90% at 1.55 mum.

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A rhodium(III)-catalyzed controllable [4 + 1] and [4 + 2] annulation of N-aryl pyrazolones with maleimides as C1 and C2 synthon has been explored for the synthesis of spiro[pyrazolo[1,2-a]indazole-pyrrolidines] and fused pyrazolopyrrolo cinnolines. The product selectivity was achieved through time-dependent annulation. The [4 + 1] annulation reaction involves sequential Rh(III)-catalyzed C–H alkenylation of N-aryl pyrazolone, followed by an intramolecular spirocyclization via aza-Michael-type addition to afford spiro[pyrazolo[1,2-a]indazole-pyrrolidine]. However, prolonged reaction time converts in situ formed spiro[pyrazolo[1,2-a]indazole-pyrrolidine] into fused pyrazolopyrrolocinnoline. This unique product formation switch proceeds via strain-driven ring expansion through a 1,2-shift of the C–C bond.

Fabry–Pérot microcavities with controllable resonant wavelengths and constant quality factors are constructed by introducing defects in periodic dielectric waveguides. Two-dimensional finite-difference time-domain method is used to simulate the field distributions in the cavities. The simulated electric field profile fits a cosine-Gaussian curve. The quadratic relation between the resonant wavelength and the defect length is theoretically discussed and numerically proved. Simulations show that the resonant wavelength can be simply controlled by shifting cylinders in the defects, and the value of quality factor keeps a constant of about 103.

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