Introgression lines (ILs) are useful tools for precise mapping of quantitative trait loci (QTLs) and the evaluation of gene action or interaction in theoretical studies. A set of 159 ILs carrying variant introgressed segments from Chinese common wild rice (Oryza rufipogon Griff.), collected from Dongxiang county, Jiangxi Province, in the background of Indica cultivar (Oryza sativa L.), Guichao 2, was developed using 126 polymorphic simple sequence repeats (SSR) loci. The 159 ILs represented 67.5% of the genome of O. rufipogon. All the ILs have the proportions of the recurrent parent ranging from 92.4 to 99.9%, with an average of 97.4%. The average proportion of the donor genome for the BC(4)F(4) population was about 2.2%. The mean numbers of homozygous and heterozygous donor segments were 2 (ranging 0-8) and 1 (ranging 0-7), respectively, and the majority of these segments had sizes less than 10 cM. QTL analysis was conducted based on evaluation of yield-related traits of the 159 ILs at two sites, in Beijing and Hainan. For 6 out of 17 QTLs identified at two sites corresponding to three traits (panicles per plant, grains per panicle and filled grains per plant, respectively), the QTLs derived from O. rufipogon were usually associated with an improvement of the target trait, although the overall phenotypic characters of O. rufipogon were inferior to that of the recurrent parent. Of the 17 QTLs, 5 specific QTLs strongly associated with more than one trait were observed. Further analysis of the high-yielding and low-yielding ILs revealed that the high-yielding ILs contained relatively less introgressed segments than the low-yielding ILs, and that the yield increase or decrease was mainly due to the number of grain. On the other hand, low-yielding ILs contained more negative QTLs or disharmonious interactions between QTLs which masked trait-enchancing QTLs. These ILs will be useful in identifying the traits of yield, tolerance to low temperature and drought stress, and detecting favorable genes of common wild rice.
Based on Density Functional Theory (DFT), using first-principles pseudopotential plane wave method, elastic properties and electronic structure of TiB2 and ZrB2 were calculated. The elastic constants of these compounds were calculated by Voigt-Reuss-Hill method. The results show that the elastic modulus of TiB2 and ZrB2 are 594 and 520 GPa, and the shear modulus are 268 and 229 GPa, respectively. Pugh empirical criterion and Poisson's ratio show that the two compounds are very brittle, and the brittleness of TiB2 is higher than ZrB2. Finally, the differences in elastic properties between TiB2 and ZrB2 result form their electronic structures.
The relationship among the composition, microstructure and strength of materials is always one of the hotspots for scholars of materials research. The influence of curing time on the compressive strength and flexural strength of the foam concrete with the cement, cement-slag and cement-steel slag as main binder respectively was studied in this paper. The microstructure of these foam concrete was analyzed by SEM and the mineral phases of the foam concrete was analyzed by XRD. The relationship among the binders, microstructure, mineral phases and strength of the foam concrete were explored and the reasons of why the strength of the cement foam concrete and cement-slag foam concrete is much higher than that of the cement-steel slag foam concrete are proposed.
In recent years, MgZnO alloy becomes one of the most suitable materials for the fabrication of ultraviolet detectors. In this paper, we have fabricated three metal semiconductor metal (MSM) photodetectors on Mg0.42Zn0.58O film grown by radio frequency magnetron sputtering. The interdigital electrodes are 500 um long and 5 um wide with an interelectrode spacing 2, 5 and 10 um, respectively. The structural, electrical and optical properties of epilayers were characterized by various techniques. At 5 V bias, a peak responsivity of 1.09 mA/W was achieved at 283 nm for the device with 2 um interelectrode spacing. The peak responsivity at 283 nm increased with the reduction of the finger pitch for three devices and the ultraviolet-visible rejection ratio (R283 nm/R400 nm) was more than one order of magnitude at 5 V bias.
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