A tight-binding analytic framework is combined with first-principles calculations to reveal the mechanism underlying the strain effects on electronic structures of graphene and graphene nanoribbons(GNRs).It provides a unified and precise formulation of the strain effects under various circumstances-including the shift of the Fermi(Dirac)points,the change in band gap of armchair GNRs with uniaxial strain in a zigzag pattern and its insensitivity to shear strain,and the variation of the k-range of edge states in zigzag GNRs under uniaxial and shear strains which determine the gap behavior via the spin polarization interaction.
An efficient method for the synthesis of N-Cbz-β-aminoalkanesulfonamides was described.N-Cbz-β-aminoalkanesulfonamides were readily prepared in good yields from a variety of amino alcohols,including optically active ones,via N-Cbz protection with benzyl chloroformate,Mitsunobu esterification reaction with thiolacetic acid,N-chlorosuccinimide oxidation,and ammonolysis process.
Reduction of graphene oxide （GO） is a promising low-cost synthetic approach to bulk graphene, which offers an accessible route to transparent conducting films and flexible electronics. Unfortunately, the release of oxygen-containing functional groups inevitably leaves behind vacancies and topological defects on the reduced GO sheet, and its low electrical conductivity hinders the development of practical applications. Here, we present a strategy for real-time repair of the newborn vacancies with carbon radicals produced by thermal decomposition of a suitable precursor. The sheet conductivity of thus-obtained single-layer graphene was raised more than six-fold to 350-410 S/cm （whilst retaining 〉96% transparency）. X-ray photoelectron spectroscopy （XPS） and Raman spectroscopy revealed that the conductivity enhancement can be attributed to the formation of additional sp2-C structures. This method provides a simple and efficient process for obtaining highly conductive transparent graphene films.
Boya DaiLei FuLei LiaoNan LiuKai YanYongsheng ChenZhongfan Liu
