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Nano-Si3N4 has been synthesized by the thermal plasma with silicon tetrachloride (SiCl4) as the Si source, liquid ammonia (NH3) as the N source, and silane (SiH4) as the catalyst. And the prepared Nano-Si3N4was heat-treated atfour different temperatures of 1350°C, 1400°C, 1450°C, 1500°C. The as-prepared samples were characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and fourier transform infrared spectroscopy (FTIR). The results showed that the particle size of the nano-Si3N4 powder was less than 100 nm and it was amorphous when the temperature below 1450°C. At 1500°C, the synthesized Si3N4 powder with the grain size of 10 nm was crystallized, and the α-phase Si3N4 reached more than 90%.

The cytological mechanism of male sterility of Shaan-GMS, a natural mutant dominant genic male sterile (DGMS) line in Brassica napus L., is not well studied. Cytological observation was made on different-size buds of DGMS line 0A30A derived from Shaan-GMS line. The pollen mother cells (PMCs) of DGMS line 0A30A were degenerating at the beginning of meiosis and could not pass the anaphase I stage, with no dyads or tetrads formed, suggesting that the DNA damage checkpoint and spindle assembly checkpoint were activated in sterile anthers. During the meiosis process of sterile anthers in the sterile plants, several kinds of abnormal meiotic cells could be observed: nuclei condensed PMCs, cells with micronuclei, collapsed cells, plasmolysis cells, cells connected with nucleoplasmic bridge, and microspore analogue developed from PMCs without meiosis but enclosed by the exine wall. The results suggested Shaan-GMS to be a new type of DGMS line in B. napus.

Piezoelectric Pb(Sb1/2Nb1/2)O3-Pb(Mn1/3Nb2/3)O3-PbZrO3-PbTiO3 (PSN-PMN-PZT) quaternary ceramics with the various contents of Pb(Mn1/3Nb2/3)O3 from 4 to 10mol% were prepared. The phase structure of the system was delineated by X-ray diffraction analysis. The surface morphology was examined by SEM. The piezoelectric and dielectric properties were also measured. X-ray diffraction patterns showed that the PSN-PMN-PZT piezoelectric ceramics was composed of tetragonal phase with perovskite-type structure. Study on the influence of Pb(Mn1/3Nb2/3)O3 additives on dielectric and piezoelectric properties indicated that the PSN-PMN-PZT quaternary system exhibited a high mechanical quality factor and well-situated piezoelectric properties. The optimized results of d33 =332pC/N, d31= -105pC/N, Kp=0.58, K31=0.34 and Qm=1658 can be obtained at 6 mol% Pb(Mn1/3Nb2/3)O3. The obtained electrical properties make this composition a good candidate for underwater acoustic devices.