Secondary metabolites of cyanobacteriaNostoc sp.

Cyanobacteria attracted much attention recently because of their secondary metabolites with potent biological activities and unusual structures. This paper reviews some recent studies on the isolation, structural, elucidation and biological activities of the bioactive compounds from cyanobacteriaNostoc species.

     

Basic theory of three-dimensional landslide modeling based on the logical model of geologic structure

Dynamic visualization of landslide cross-sections is important for understanding the structure and mechanism of landslide formation. Moreover, the modeling of geologic information plays an effective role in geo-hazard assessment and their mitigation. In this study, we developed the basic theory of a three-dimensional landslide modeling and applied it to the Nigawa landslide of the Hyogo Prefecture in central Japan. The construction of this model is based on the boundary surfaces of slump blocks and geologic units, and the hierarchical relationships between these surfaces. An application algorithm was validated and the model proved efficient in depicting the nature of landslides in the Nigawa area.     

饱和珊瑚砂液化特性动三轴试验研究

为调查饱和珊瑚砂液化相关特性与发展规律,针对饱和Chibishi珊瑚砂,开展一系列不排水循环三轴试验,研究相对密度D_r和循环应力比CSR对饱和Chibishi珊瑚砂的超孔隙水压力Δu、轴向应变ε_a及动强度特性的影响,并分析不同地区珊瑚砂抗液化强度的差异性。结果表明,饱和Chibishi珊瑚砂的Δu发展模式根据不同的CSR水平可以分为前期均匀增长型、前期突增型和后期突增型;此外,采用一种新的孔压模型对前期均匀增长型、前期突增型的孔压比r_u进行表征,Chibishi珊瑚砂在相同的D_r条件下,双幅应变ε_DA达到5%的循环次数N随着CSR水平的增加而逐渐减小;各珊瑚砂在同一里氏震级对应的等效循环振动次数下,抗液化强度CRR的增长模式存在显著差异。研究结果可丰富对珊瑚砂液化特征的认知,同时对近岸和沿海工程的抗震设计提供参考依据。