福建省近岸海域海洋生态健康评价与分析

根据《近岸海洋生态健康评价指南》中的“河口及海湾生态系统生态环境健康评价方法“,利用2006年~2010年以来福建省环保厅的近岸海域监测网络的监测数据及相关文献资料,对福建省近岸海域的海洋生态健康状况进行分析评价。评价结果显示:福建省近岸海域生态系统健康指数为60.3,处于亚健康状态,其中水环境、沉积物、生物残毒和栖息地环境处于健康状态,而生物处于不健康状态。根据当前实际情况,该文从法律保障、管理机制和补偿机制等方面提出了适合保持生态健康的具体策略,为推动福建近岸海域经济发展与海域生态健康可持续发展提供参考

Drag reduction using riblets downstream of a high Reynolds number inclined forward step flow

Micro-riblet is an efficient passive method for controlling turbulent boundary layers, with the potential to reduce frictional drag. In various applications within the transportation industry, flow separation is a prevalent flow phenomenon. However, the precise drag reduction performance of riblets in the presence of flow separation remains unclear. To address this, an inclined forward step model is proposed to investigate the interaction between riblet and upstream flow separation. The large eddy simulation (LES) method is applied to simulate the flow over geometries with different step angles and riblet positions. The results show riblets still reduce wall frictional resistance when subjected to the upstream flow separation. Remarkably, as the angle of the step increases from 0 degrees to 30 degrees, the drag reduction experiences an increment from 9.5% to 12.6%. From a turbulence statistics standpoint, riblets act to suppress the Reynold stress in the near-wall region and dampen ejection motions, thus weakening momentum exchange. Quadrant analysis reveals that with the augmentation of flow separation, the Q2 motion within the flow field intensifies, subsequently enhancing the riblet-induced drag reduction. Moreover, the position of the rib lets has a significant impact on the pressure drag. Riblets close to the point of separation enhance flow separation, altering the surface pressure distribution and thus increasing the resistance. The results reveal that when the riblets are positioned approximately 160 riblet heights away from the step, their effect on the upstream flow separation becomes negligible. The precise performance of riblets under complex flow conditions is important for their practical engineering application

石斛属植物生物碱成分研究进展

生物碱是药用石斛重要的生理活性成分,是金钗石斛Dendrobiumnobile的特征药效成分。石斛属植物中共获得52个生物碱成分,依据结构分为5种,包括倍半萜类、八氢中氮茚类、酰胺碱类、四氢吡咯类和咪唑类生物碱。倍半萜类生物碱又划分为石斛碱型、石斛星型、石斛酮型等。含有生物碱的石斛共有19种,主要有金钗石斛、束花石斛D. chrysanthum、玫瑰石斛D. crepidatum、棒节石斛D. findleyanum、黄喉石斛D. signatum、铬黄石斛D. friedericksianum等。对石斛属植物中生物碱的结构分类、含生物碱的石斛种类以及石斛属生物碱含量的影响因素研究现状进行综述,以期为石斛属生物碱的深入研究及开发提供参考