Effects of Mutation and Hybridization on Breeding of Super High Yield Wheat Varieties

In order to develop high quality wheat varieties with super high yield, a theory which improved the genetic difference between parents by performing radi- ation mutation on them to enhance heterosis was proposed. The dry seeds treated and planted last year were radiated frequently by X- ray from 2003 to 2004. Then the dry seeds were radiated by high energy X ray combined with nuclear magnetic resonance from 2005 to 2007. We have treated the dry seeds repeatedly for 3 years and gained a variety of aberrant plants. These mutants were used as parents that were hybridized with the best plants in field. It was shown that a lot of mutant plants appeared in the f＇llial generations. After that, we selected big grains and super big grains among them. The result showed that, middle stem plants with big grains and low stem plants with big grains appeared. This phenomenon might be due to the breakthrough of linkage relationship between big grain trait and high stem trait. With the technique practice and materials, the new thoughts and methods were provided for induction and utilization of heterosis of wheat, which created a va- riety of seed selection and breeding materials for breeding super wheat varieties.

In-situ growth of low-dimensional perovskite-based insular nanocrystals for highly efficient light emitting diodes

Regulation of perovskite growth plays a critical role in the development of high-performance optoelectronic devices.However,judicious control of the grain growth for perovskite light emitting diodes is elusive due to its multiple requirements in terms of morphology,composition,and defect.Herein,we demonstrate a supramolecular dynamic coordination strategy to regulate perovskite crystallization.The combined use of crown ether and sodium trifluoroacetate can coordinate with A site and B site cations in ABX_(3) perovskite,respectively.The formation of supramolecular structure retard perovskite nucleation,while the transformation of supramolecular intermediate structure enables the release of components for slow perovskite growth.This judicious control enables a segmented growth,inducing the growth of insular nanocrystal consist of low-dimensional structure.Light emitting diode based on this perovskite film eventually brings a peak external quantum efficiency up to 23.9%,ranking among the highest efficiency achieved.The homogeneous nano-island structure also enables high-efficiency large area(1 cm^(2))device up to 21.6%,and a record high value of 13.6%for highly semi-transparent ones.

ADI-FDTDMethod for Two-Dimensional Transient Electromagnetic Problems

An efficient and accurate numerical scheme is proposed for solving the transverse electric(TE)mode electromagnetic(EM)propagation problemin two-dimensional earth.The scheme is based on the alternating direction finite-difference time-domain(ADI-FDTD)method.Unlike the conventional upward continuation approach for the earth-air interface,an integral formulation for the interface boundary is developed and it is effectively incorporated to the ADI solver.Stability and convergence analysis together with an error estimate are presented.Numerical simulations are carried out to validate the proposed method,and the advantage of the present method over the popular Du-Fort-Frankel scheme is clearly demonstrated.Examples of the electromagnetic field propagation in the ground with anomaly further verify the effectiveness of the proposed scheme.