酵母菌种的单倍体分离及其原生质体的再生、融合的研究

采用酶法和复合作用法对酵母菌株 13 0 0 (2N)和 2 0 10 (2N)的单倍体细胞 (1N)的获得率分别为3 0 %和 2 0 %左右 由实验确定脱子囊壁的最佳条件为采用生理盐水 ,pH5 .4 ,温度为 2 7℃ ,获得A型 ,B型两种单倍体细胞 (IN) 通过群体杂交法 ,从 75个平板上 ,挑选出 14 5个小菌落 ,得到 5个营养缺陷型菌株 ,该菌株的原生质体在 3 5 %PEG的作用下进行原生质体的融合 ,获得成功 但是仍需进一步对融合体进行生理、生态的研究     

An algorithm based on evidence theory and fuzzy entropy to defend against SSDF

In cognitive radio networks, spectrum sensing is one of the most important functions to identify available spectrum for improving the spectrum utilization. Due to the open characteristic of the wireless electromagnetic environment, the wireless network is vulnerable to be attacked by malicious users(MUs), and spectrum sensing data falsification(SSDF) attack is one of the most harmful attacks on spectrum sensing performance. In this article,an algorithm based on the evidence theory and fuzzy entr...     

Passive-source ocean bottom seismograph （OBS） array experiment in South China Sea and data quality analyses

Long-term passive source ocean bottom seis- mograph （OBS） observatory is challenging due to various technical difficulties. In order to gain experience in this field, and to reveal the lithospheric structure beneath the extinct ridge in the central South China Sea （SCS）, we carried out a passive source OBS array experiment, which includes 18 OBSs, in the deep portion of SCS. Here we present the instrumentation, the OBS deployment and recovery of this experiment, and more importantly, the data quality evaluated by a number of approaches. Through processing and inspecting waveforms from global, regional and local earthquakes, we find that most of recovered OBSs have good data quality with discernible main phases. The ambient noise analyses of OBS recordings show that their noise is higher than the global average, and the horizontal component is noisier than the vertical, indicating current impacts on horizontal components are more severe. In the period range of 5-10 s, there is a noise notch for the SCS OBSs, and noise levels of horizontal components are comparable to the vertical. This feature, which is not seen at OBS stations in open ocean, suggests the distant sources for double frequency microseism in this marginal sea are not significant. In addition, we successfully determined the orientations for 7 OBSs by investigating their Rayleigh wave polarizations; and we demonstrated the dispersion feature of Rayleigh waves through the frequency-time analysis. Finally, we summarized lessons learned from this experiment regarding the passive source OBS investiga- tions in SCS.     

Synthesis and performance of Ca-α/β-SiAlON composites from tailings

Ca-α/β-SiAlON composites were prepared using Ca-α/β-SiAlON powder synthesized from gold ore tailings, which contained abundant Si and Al elements as the major raw materials together with minor additives, through a pressure-less sintering method. The influences of sintering temperature on the phase composition and microstructure of the composites were analyzed. The scanning electron microscopy images of the composites show the interlacing of grains with elongated columnar, short columnar and plate-like morphologies. The composites sintered at 1520℃ for 6 h have a flexural strength of 352 MPa, Vickers hardness of 11.2 GPa, and fracture toughness of 4.8 MPa·m1/2. The relative content of each phase in the products is I(Ca-α-SiAlON):I(β-SiAlON):I(Fe₃Si) = 23:74:3, where I_i stands for the diffraction peak intensity of phase i.     

Study on contrast test of PPC pre-oxidation and coagulation for algae removal and deodorization

The effect of treating algae-bearing water and induced odor by use of permanganate potassium composite （PPC） pre-oxidation was investigated, and was compared with the effect of treatments by pre-chlorination, permanganate petassium pre-oxidation and simple coagulation. The results showed that simple coagulation and pre-chlorination were less effective in removing algae and its odor, whereas PPC pre-oxidation was the most effective in algae removal and deodorization. Upon oxidation with PPC, the cells of Oscillatoria agardhic were inactivated and some intra-cellular and extra-cellular components were released into the water, which may help the coagulation by their bridging effect. The efficient removal of algae by PPC pre-oxidation is believed to be the joint contribution of several mechanisms.     

Epitaxial growth of Fe/Ag single crystal superlattices and their magnetic properties

Single crystal Fe/Ag(001) superlattices with various periodicities were fabricated using ultrahigh vacuum evaporation deposition. It was found that single crystal bcc Fe layers and single crystal fcc Ag layers can epitaxially grow on a single crystal Ag buffer layer alternately, which was deposited on NaCl single crystal chips by ion beam assisted deposition. The magnetic measurements of the superlattices reveal an oscillation coupling between ferromagnetism and antiferromagnetism as a function of the Ag layer thickness. The oscillation period, which is 1 nm (5 Ag layers), is in good agreement with the calculated values when the Ag thickness is greater than 1.5 nm. While the thickness of the Ag spacer layer decreases to 1 nm, the oscillation coupling varies from calculations, which can be attributed to the intermixing of the interlayers according to the annealing results.     

Tangential stress analysis of myocardial wall by finite element method

A novel method is presented to build the triangular surface model and calculate the tangential stress and strain of myocardial wall ,which can be further used to reflect the left ventricle twisting—a sensitive index to assess the systolic and diastolic function of heart. Firstly, a point distribution model is used to obtain the feature points of the ventricular surface in medical images. Secondly, the surface model is constructed by triangular mesh, and then the subdivision strategy is introduced to refine the model. Thirdly, plane projection and finite element method(FEM) are applied to calculate the tangential stress and strain.Finally, the distribution of tangential modulus of elasticity is discussed. The stimulation results show that the proposed method can be used to compute the tangential stress and strain of myocardial wall effectively and the computing result is consistent with the results mentioned in the literatures.     

复合式静电感应电极水雾喷头的研究

研究设计了一种复合式静电感应电极水雾喷头，它具有结构简单，荷电效果好，安全可靠等特点，并且克服了由于雾滴水流造成裸露电极的短路现象，同时该结构还避免了荷电后的水雾对密闭电极的静电屏蔽效应。