Diversity of bacterial community structure and its driving factors in three bays of Bohai Sea

[Background] Sustainable development of coastal ecosystem has become one of the most important concerns for people nowadays. Riverine output and anthropogenic interrupt have important impacts on the coastal environment. [Objective] In this study, we collected 12 samples from three transects including Bohai Bay, Liaodong Bay and Laizhou Bay to explore the microbial community and diversity in summer of 2015. [Methods] DNA was extracted from water samples by using DNA extraction kit. Samples were analyzed by Illumina HiSeq sequencing technology. We compared the differences among these three transects according to the analysis results. [Results] The diversity index and rarefaction curves showed significant differences among these three transects. The order of diversity value was Laizhou Bay>Bohai Bay>Liaodong Bay. The distribution of the dominant community was as follows: the proportion of Proteobacteria, Bacteroidetes, Cyanobacteria, Actinobacteria and Planctomycetes in the Bohai Bay was 39.8%, 25.7%, 22.4%, 5.85% and 4.38%, respectively. The dominant community proportion in Liaodong bay was Proteobacteria (37.8%), Bacteroidetes (25.7%), Cyanobacteria (17.8%), Actinobacteria (10.4%) and Planctomycetes (5.64%). While in Laizhou Bay there were only four dominant communities as follows: Proteobacteria (59.0%), Bacteroidetes (17.5%), Cyanobacteria (8.2%), Actinobacteria (7.88%). By using the principal component analysis (PCA) and Heatmap correlation analysis, we found that environmental factors were key roles in controlling the microbial diversity in the Bohai Sea. Among them, the concentration of nitrate was particularly significant according to the Mantel test analysis. [Conclusion] The microbial diversity in the three bays of Bohai Sea was very rich and multifarious. The population structure and species in the Laizhou Bay is the most complex and abundant among these three bays, and then it is Bohai Bay and Liaodong Bay. There was a significant correlation among microbial diversity, environmental factors and the spatial distribution. Above all, this study will provide a theoretical basis for further protection and ecological development of Bohai Sea

一种制备聚酰亚胺模塑粉的方法

本发明是关于一种制备高性能聚酰亚胺模塑粉的方法。本发明将化学酰亚胺化法与热酰亚胺化法相结合来制备聚酰亚胺模塑粉，具体地说，是将至少种芳香族酸酐和至少一种芳香族二元胺于溶剂中聚合生成聚酰胺酸溶液，在5～40℃下进行化学酰亚胺化后，加热至50℃～250℃进行热酰亚胺化反应，得到聚酰亚胺模塑粉。由该方法制备的聚酰亚胺模塑粉质量稳定，性能优良。带填

Distribution of the Net-Phytoplankton Community and Chlorophyll-a in the Bohai Sea in Summer and Its Impacts on Fishery Resources

Phytoplankton are the major primary producers in the ocean and play a crucial role in the marine food chain. Understanding the dynamics of the marine phytoplankton community can provide insights into the succession process and current status of marine fishery resources. Based on the net-phytoplankton samples collected from the Bohai Sea in the summer (June and August) of 2015, we studied the phytoplankton community composition, diversity, abundance, and dominant taxa in the Bohai Sea. Compared with historical data, the phytoplankton community structure in the Bohai Sea was changed markedly. The chlorophyll-a concentration had changed slightly during recent years, but was much higher than that in the 1980s and 1990s, and the regions with lower values (&lt;1.0 g/L) were much smaller than those 20 years ago. In terms of the dominant taxa, the dominance of the genera Chaetoceros and Coscίnodiscus was found to be slightly decreased, whereas the species Skeletonema costatum, which had been an important dominant species in the Bohai Sea, was not observed in the two months of summer in 2015. In contrast, Paralia sulcata and Pyrrophyta (Noctiluca scientillans in June and Ceratium tripos in August) were still dominant in the Bohai Sea, and the abundance and dominance of Achnanthes brevipes and Pseudo-nitzschia pungens was higher than those in the years before 2015. The diversity indices (Shannon diversity and species richness and evenness) of phytoplankton were at a moderate level. Such a trend was mainly caused by the significant change of the nutrient structure in the Bohai Sea. This may change the structure of the marine food chain and influence the growth and reproduction of commercial fishes and shrimps (e.g., Konosirus punctatus, Liza haematocheila, and Acetes chinensis) that feed on phytoplankton. Consequently, this will have potential impacts on fishery production and the structure and function of the ecosystem in the Bohai Sea.</p

A study of the influence of initial liquid volume on the capillary flow in an interior corner under microgravity

In this work the influence of initial liquid volume on the capillary flow in an interior corner is studied systematically by microgravity experiments using the drop tower, under three different conditions: the Concus-Finn condition is satisfied,close to and dissatisfied. The capillary flow is studied by discussing the movement of tip of the meniscus in the corner. Experimental results show that with the increase of initial liquid volume the tip location increases for a given microgravity time, the achievable maximum tip velocity increases and the flow reaches its maximum tip velocity earlier However, the results for the three different conditions show some difference. (C) 2010 Elsevier Ltd All rights reserve

Influence of Contact Angle and Tube Size on Capillary-Driven Flow Under Microgravity

The influence of contact angle and tube radius on the capillary-driven flow for circular cylindrical tubes is studied systematically by microgravity experiments using the drop tower. Experimental results show that the velocity of the capillary flow decreases monotonically with an increase in the contact angle. However, the time-evolution of the velocity of the capillary flow is different for different sized tubes. At the beginning of the microgravity period, the capillary flow in a thinner tube moves faster than that in a thicker tube, and then the latter overtakes the former. Therefore, there is an intersection between the curves of meniscus velocity vs microgravity time for two differently sized tubes. In addition, for two given sized tubes this intersection is delayed when the contact angle increases. The experimental results are analyzed theoretically and also supported by numerical computations

Experimental study on the capillary flow in tubes of different shapes under microgravity condition

利用落塔设施创造的短时间微重力条件, 研究了不同尺寸的正方形和三角形截面的毛细管中的流体在微重力条件下的流动行为, 并与圆形毛细管中的毛细流动进行了对比, 总结出了毛细管尺寸和截面形状对界面张力主导的毛细流动行为的影响规律. 结果显示, 对于同样形状的毛细管, 其尺寸对于毛细流动的影响规律基本相同; 而对于不同的截面形状, 方形管和三角形管都与截面积小得多的圆形管有一定的类似性. 相关结果对于深入理解不同条件下的界面张力主导的毛细流动特性, 以及在空间微重力条件下通过改变毛细管的形状来实现流速和流量的独立控制等方面都具有明显的现实意义

Rhizosphere microbial community structure and function of Zostera japonica in the distribution area of seagrass beds in the Yellow Sea and Bohai Sea

Zostera japonica is a unique Asian seaweed species and has important ecological value. In recent years, Zostera japonica has been continuing to degenerate, causing widespread concern among researchers. [Objective] We hypothesized that the rhizospheric microorganisms were closely related with the healthy growth of Zostera japonica. We explored the diversity and function of microbial community in root of Zostera japonica at coastal zone of Yellow sea and Bohai sea, and intrinsic relationship with seagrass. [Methods] We collected surface sediment samples of Zostera japonica roots and unvegetated areas from three locations including Dongying, Weihai, and Dalian city. We investigated the rhizosphere microbial community structure by sequencing on Illumina HiSeq300 platform and analyzed the correlation between microbial community structure and environmental parameters. [Results] The most dominated phyla widely distributed in the rhizospheric surface sediments of Zostera japonica included: Proteobacteria (41.1%), Cyanobacteria (15.4%), Bacteroidetes (12.6%), Actinobacteria (9.3%). Comparisons of different regions (Weihai, Dongying, and Dalian) or sample types (rhizosphere vs. non-rhizosphere) showed significant differences in microbial communities, mainly due to the presence of sulfate-reducing bacteria and nitrogen-fixing bacteria found in the rhizosphere. Total nitrogen, total carbon, total organic carbon, clay, were all significantly correlated to rhizospheric bacterial community composition and distribution. [Conclusion] From a functional point of view, the differences between groups was mostly related to sulfur and nitrogen cycling, and sulfate reducing bacteria play a key role in maintaining the ecological health of Zostera japonica.</p

Preparation of Exo-tetrahydrotricyclopentadiene Based High Energy Density Fuels

Preparation of Exo-tetrahydrotricyclopentadiene Based High Energy Density Fuel

Synthesis of Silicalite-1 Membranes on the Surface of Stainless Steel

Silicalite-1 (pure silica MFI) membranes were hydrothermally synthesized on pretreated surface of two common stainless steel materials, i.e., AISI 304 and 316L. XRD and SEM techniques were used to characterize the membranes. Various membrane morphologies can be obtained by adjusting synthesis conditions such as the H2O/SiO2 ratio in the start colloid, the crystallization time and temperature as well as the substrate materials. The silicalite-1 membranes on the stainless steel surface show potential applications for regenerative fuel cooling technology in high speed flight field.Silicalite-1 (pure silica MFI) membranes were hydrothermally synthesized on pretreated surface of two common stainless steel materials, i.e., AISI 304 and 316L. XRD and SEM techniques were used to characterize the membranes. Various membrane morphologies can be obtained by adjusting synthesis conditions such as the H2O/SiO2 ratio in the start colloid, the crystallization time and temperature as well as the substrate materials. The silicalite-1 membranes on the stainless steel surface show potential applications for regenerative fuel cooling technology in high speed flight field