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Researchers recently synthesized a new orthorhombic allotrope of silicon, namely Cmcm Si24. This work studied the effect of one vacancy for Cmcm Si24 on structural, electronic, and mechanical anisotropy properties by the first principle calculation. The lattice parameters of Cmcm Si24:V are the same as Cmcm Si24, but the density of Cmcm Si24:V is larger than that of Cmcm Si24. Moreover, the values of elastic moduli for Cmcm Si24:V are smaller than for Cmcm Si24. The Cmcm Si24:V has mechanical stability and anisotropy and has lower formation energy than diamond-Si. The analysis of the band structures shows that Cmcm Si24 is an indirect band gap material, and the value of the band gap is 1.08 eV. In particular, electronic band structures of Cmcm Si24:V exhibit metallic characteristics. Furthermore, the electron localization function indicated strong covalent silicon--silicon bonds in Cmcm Si24 and Cmcm Si24:V. In addition, the effective mass of electrons and holes of Cmcm Si24 is smaller than that of diamond-Si along the a direction, and larger than that along the b and c directions. Finally, the X-ray diffraction patterns for Cmcm Si24 and Cmcm Si24:V are very close after 13:84°. [ABSTRACT FROM AUTHOR]

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Drought-tolerant ( DT) maize ( Zea mays L.) hybrids have potential to increase yield under drought conditions. However, little information is known about the physiological determinations of yield in DT hybrids. Our objective was to assess radiation-use efficiency ( RUE), biomass production, and yield in two hybrids differing in drought tolerance. Field experiments were conducted in 2013 and 2014 with two hybrids, P1151 HR ( DT hybrid) and 33D49 (conventional hybrid) under well-watered (I100) and drought (I50) conditions. I100 and I50 refer to 100 % and 50 % evapotranspiration requirement, respectively. On average, P1151 HR yielded 11-27 % greater than 33D49 at I100 and about 40 % greater at I50, At I100, greater yield in P1151 HR was due to greater biomass at physiological maturity ( BMpm) resulting from greater post-silking biomass accumulation ( BMpost). At I50, both hybrids had similar BMpm but P1151 HR showed a higher harvest index and greater BMpost. RUE differed significantly (P < 0.05) between the hybrids at I100, but not at I50. At I100, the RUE values for P1151 HR and 33D49 were 4.87 and 4.28 g MJ−1 in 2013, and 3.71 and 3.48 g MJ−1 in 2014. At I50, the mean RUE was 3.89 g MJ−1 in 2013 and 3.16 g MJ−1 in 2014. Results indicate that BMpost is important for maintaining high yield in DT maize. [ABSTRACT FROM AUTHOR]