Dissipation source function and an improvement to LAGFD-WAM model

In this paper, a new theoretical expression of dissipation term is presented on the basis of statistical model of breaking wave, which is an improvement to LAGFD-WAM wave model. The computational results in three typical wind fields show a good improvement to LAGFD-WAM model and a better accuracy in comparison with the observed data in the South China Sea.     

Isolation, distribution and evaluation of cytotoxic and antioxidant activity of cultivable actinobacteria from the Oman Sea sediments

Screening bioactive natural products from bacteria is a determinative step in the drug discovery programs. The present study aim to isolate actinobacteria from the Oman Sea sediments for determining the effects of different culture media and treatments on the yield of the isolation process, and measure the DPPH radical scavenging and Artemia cytotoxic activity of culture extracts of the actinobacterial isolates. A total of 290 actinobacterial isolates were collected from 14 sediment samples. Heat treatment(40.68%) and M_4 medium(29.31%) exhibited the maximum isolation rates of actinobacteria. Streptomyces isolates were dominantly distributed in all of the investigated stations according to 16 S rRNA gene sequencing. The distribution pattern of Streptomyces followed a depth-dependent frequency trend, whereas the members of rare genera including Micromonospora, Nocardia Actinoplanes, Nocardiopsis, Saccharopolyspora and Crossiella were distributed in deeper stations. Approximately,25% of the examined isolates could scavenge 90% of 10~(–4) mol/L DPPH solutions at 1 250 μg/mL final concentration of their ethyl acetate culture extracts. Furthermore, the most potent extracts could scavenge DPPH radicals with IC50 ranges from 356.8 to 566.4 μg/mL. Brine shrimp cytotoxicity tests showed that 38.88% of the examined culture extracts exhibited LC_(50) lower than 1 000 μg/mL against the Artemia cells. Moreover, the most potent culture extracts exhibited LC_(50) range from 335.4 to 534.4 μg/mL. Phylogenetic analysis by 16 S rRNA gene sequence revealed that the OS 005, OS 263 and OS 157 closely related to Streptomyces djakartensis, Streptomyces olivaceus and Nocardiopsis dassonvillei respectively. These results suggested the widespread distribution of the antioxidant and cytotoxic producing actinobacteria in the Oman Sea sediments, which could be considered as promising candidates for the discovery of microbial bioactive compounds.     

脊尾白虾蜕皮抑制激素基因全长cDNA的克隆及其对环境胁迫的响应

为研究脊尾白虾蜕皮抑制激素基因(MIH)在环境适应中的作用,本文采用RACE技术从蜕皮间期脊尾白虾眼柄中克隆获得MIH-like基因全长c DNA序列,命名为Ec MIH。该基因全长1218bp,包括360bp的开放阅读框,420bp的5'端非编码区和394bp的3'端非编码区;开放阅读框编码120个氨基酸,包括41个氨基酸组成的信号肽和79个氨基酸组成的成熟肽,预测蛋白分子量为13.71k Da,理论等电点p I为8.02。同源性比较分析发现,脊尾白虾MIH-like基因与日本沼虾和罗氏沼虾同源性最高,分别为87%和86%。荧光定量PCR分析结果表明,脊尾白虾MIH-like基因在眼柄中的表达量最高,在卵巢中的表达量最少,而在肝脏、肌肉、鳃和血细胞中不表达。环境胁迫后该基因具有明显的时序性。p H6.5胁迫后24h和48h,眼柄和腹神经节中MIH-like基因的表达量较对照组均显著增加(P0.05);4mg/L氨氮浓度组胁迫后12h和24h,眼柄和腹神经节中MIH-like基因的表达量较对照组均显著增加(P0.05);盐度39胁迫后12h和24h,眼柄和腹神经节中MIH-like基因的表达量较对照组均显著增加(P0.05)。本研究结果表明脊尾白虾mih基因参与了环境胁迫后的机体应激反应。     

南江县铁炉坝地区含金丰度及金矿化围岩蚀变特征

对四川省南江县铁炉坝地区各类岩石和土壤的含金丰度进行了阐述，对金矿化的围岩蚀变特征进行了较详细的论述，指出黄铁矿化一电气石化-硅化的蚀变组合是该区金成矿的指示性标志。     

Sedimentary characteristics of terrigenous debris at site MD05-2905 in the northeastern part of the South China Sea since 36 ka and evolution of the East Asian monsoon

Sediments with high sedimentation rate at site MD05-2905 in the Northeastern slope of the South China Sea provide unique materials for a high-resolution study on the paleoenvironment. Based on precise dating of AMS ¹⁴C, grain size analysis of terrigenous debris at core MD05-2905 was conducted after organic matter, biological carbonate and biogenic opal were removed. The results show that 15.5–63.5 μm coarse grain size ingredients may indicate East Asian winter monsoon changes and that 2–9 μm fine grain size ingredients may be used as a proxy of evolution of the East Asian summer monsoon. The results of grain size analysis, which suggest East Asian monsoon intensity, reveal that a winter monsoon dominated the glacial regime and a summer monsoon dominated the Holocene regime. It was also shown that the summer monsoon increased gradually, experienced several abrupt changes and reached a culmination in the early Holocene (11200–8500 a B.P.) since 36 ka. Controlled by precession periodicity, it may be related with the amount of solar radiation at the highest stage, which needs further study. __________ Translated from Advances in Earth Science, 2007, 22(10): 1012–1018 [译自: 地球科学进展]     

Comparative Studies of Different Mesoscale Convection Parameterization Schemes in the Simulation of Mei-Yu Front Heavy Rain

The mei-yu front heavy rainstorms occurred over Nanjing on 3 5 and 8 9 July 2003 and were simulated in this paper using the Weather Research and Forecasting Model (WRFv3.1) with various mesoscale convection parameterization schemes (MCPSs). The simulations show that the temporal and spatial evolution and distribution of rainstorms can be modeled; however, there was incongruity between the comparative simulations of four different MCPSs and the observed data. These disparities were exhibited in the simulations of both the 24-hour surface rainfall total and the hourly precipitation rate. Further analysis revealed that the discrepancies of vertical velocity and the convective vorticity vector (CVV) between the four simulations were attributed to the deviation of rainfall values. In addition, the simulations show that the mid-scale convection, particularly the mesoscale convection system (MCS) formation, can be well simulated with the proper mesoscale convection parameterization schemes and may be a crucial factor of the mei-yu front heavy rainstorm. These results suggest that, in an effort to enhance simulation and prediction of heavy rainfall and rainstorms, subsequent studies should focus on the development and improvement of MCPS.     

Confidence Evaluation of Medium-and Long-Term Earthquake Prediction by Use of the Analytical Hierarchy Process

This paper offers an approach to the relative confidence level of medium- and long-term earthquake prediction methods by use of the analytical hierarchy process (AHP). We construct the criterion judgment matrices according to the results of an expert questionnaire known as the Delphi scheme. From the matrices we can obtain a scale for the relative preference or priority weight of each factor. The quantitative weights might be applied to make synthetic prediction of earthquake risk areas in the northern part of the North China seismic region.     

耿达短水准异常与汶川8.0级地震

结合龙门山断裂带其他跨断层资料,对耿达短水准在汶川8.0级地震前后的观测资料进行了重新分析,发现耿达短水准在汶川地震前后的异常为当地居民修建生活小区所致,不应视为地震前兆异常。     

生态功能优先背景下的西南岩溶区石漠化治理问题

文章分析了现有石漠化治理模式、物种选择、石漠化治理综合效益评估、消除贫困等方面存在的不足,并结合国家对西南岩溶石漠化区主体生态功能的定位,对未来石漠化治理过程中的几个关键问题进行了探讨,认为未来石漠化治理要更有效地兼顾生态与经济效益,提高生态补偿标准,完善生态补偿体制,促进石漠化区农村人口的城镇化转移,减少人口压力,消除农户破坏环境的驱动因素,促进石漠化治理成效的长期可持续发展,以保证西南岩溶石漠化区水土保持和生物多样性维护主体生态功能的实现。      

土壤质量评价国外研究进展

土壤是人类赖以生存的根本资源。土壤质量涉及到动植物生产力,大气、水的质量和人类的健康,随着人们对自然资源和环境保护意识的增强,越来越多的国家和地区已将土壤质量评价工作作为实现可持续发展的一个重要方面。通过土壤质量评价,了解土壤管理和利用的现状,为土壤质量的改善及可持续利用提供理论依据和技术支撑。根据国外近10年的研究,总结了主要的评价指标体系和评价方法。评价指标主要包括土壤物理、化学和生物性质3个方面的指标。评价方法分为定性和定量评价,定量评价应用较广,包括土壤质量指数、土壤质量模型、多元线性回归、相对土壤质量法等。掌握和了解国外相关研究的动态,对于开展土地质量地球化学评估及土地的分等定级工作有着重要的意义。