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

某院鲍曼不动杆菌血流感染治疗方案的制定

目的:制定某院鲍曼不动杆菌血流感染的治疗方案。方法:收集某院2015-2016年血标本培养出的鲍曼不动杆菌39株,测定对氨苄西林舒巴坦,替加环素,亚胺培南,美罗培南的最低抑菌浓度。运用蒙特卡洛方法计算不同方案的达标概率(PTA)和累积反应分数(CFR)。结果:氨苄西林舒巴坦3 g q6h对鲍曼不动杆菌的CFR为66.05%,替加环素50 mg q12h,100mg q12h的CFR分别为95.75%和99.77%,亚胺培南1 g q8h,q6h和美罗培南1 g q8h,q6h的CFR分别是67.74%,96.56%和74.19%,88.8%。结论:某院鲍曼不动杆菌血流感染时,经验选择可用替加环素50 mg q12h,100 mg q12h和亚胺培南1 g q6h方案。目标治疗应根据最低抑菌浓度(MIC)情况选择方案

Asymmetric Migration of Human Keratinocytes under Mechanical Stretch and Cocultured Fibroblasts in a Wound Repair Model

Keratinocyte migration during re-epithelization is crucial in wound healing under biochemical and biomechanical microenvironment. However, little is known about the underlying mechanisms whereby mechanical tension and cocultured fibroblasts or keratinocytes modulate the migration of keratinocytes or fibroblasts. Here we applied a tensile device together with a modified transwell assay to determine the lateral and transmembrane migration dynamics of human HaCaT keratinocytes or HF fibroblasts. A novel pattern of asymmetric migration was observed for keratinocytes when they were cocultured with non-contact fibroblasts, i.e., the accumulative distance of HaCaT cells was significantly higher when moving away from HF cells or migrating from down to up cross the membrane than that when moving close to HF cells or when migrating from up to down, whereas HF migration was symmetric. This asymmetric migration was mainly regulated by EGF derived from fibroblasts, but not transforming growth factor alpha or beta_1 production. Mechanical stretch subjected to fibroblasts fostered keratinocyte asymmetric migration by increasing EGF secretion, while no role of mechanical stretch was found for EGF secretion by keratinocytes. These results provided a new insight into understanding the regulating mechanisms of two or three-dimensional migration of keratinocytes or fibroblasts along or across dermis and epidermis under biomechanical microenvironment

Calculation on Dynamic Coefficients of Annular Seals in Centrifugal Pumps

本文根据Hirs的紊流整体流动理论,研究了离心泵间隙密封的动量方程式,在此基础上,推导了计算动力学系数的微分方程组,进行了数值求解并对计算结果进行了分析比较

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

Determination of Zirconium in Soil Samples

本文介绍用偶氮胂Ⅲ作显色剂,以分光光度法测定土壤中锆的方法。zr(Ⅳ)在酸性介质中与偶氮胂Ⅲ形成蓝紫色络合物,最大吸收波长在660nM。方法的检测限为2ng。土壤样品以nA_2O_2熔融予处理,分离掉多数干扰离子。方法用于标准土壤样品的测定,变异系数<2%,测定值与标准值的相对误差<10%。In this artical is introducod the determination of zirconium in soil using spectropho- tometry,with arsenazo Ⅲ as color-developing reagent.The limit of The determintion is 2 ng.The RSD are<2% The soil sample is melted with Na_2O_2 in pretreatment to separate most of the in- terFering ions

Omnibearing position transducer

本发明公开了一种用于移动载体的全方位位置传感器。其中与码盘同轴安装的电机通过安装板与传动减速机构啮合,装有镜片的旋转头在传动减速机构上与上安装架轴承连接,一侧置有光电接收器的调制激光发射器固定于安装板上,位于传动减速机构下面,信号选择器输入端与调制激光发射器和光电接收器输出端连接,单片机数据采集处理器输入端为码盘和信号选择器,与旋转头同一水平面的空间设置多个合作目标。它能增强移动载体运行的自治能力,作业效率高,灵活性能强

EA4T车轴钢的高周和超高周疲劳性能研究

研究了2组EA4T车轴铜的高周和超高周疲劳性能，一组是现车用的欧系EA4T车轴试样，一组是试验用车轴钢25CrMo4试样、采用旋转弯曲疲劳试验机进行疲劳试验，结果表明,当应力水平较低时．2批试样均未发生10^8周次的疲劳断裂。疲劳断口的扫描电子显微镜观测显示，裂纹均从试样表面起源。S-N试验数据结果比较表明，试验用的车轴钢25CrMo4具有更好的疲劳性能

氮化镓基发光二极管电流阻挡层的制作方法

&nbsp;一种氮化镓基发光二极管电流阻挡层的制作方法,包括如下步骤：步骤1：取一氮化镓LED外延片,该外延片由衬底,N型氮化镓,多量子阱,铝镓氮EBL和P型氮化镓组成；步骤2：将该氮化镓LED外延片隔离成多个重复单元,每个单元就是一个独立的LED芯片；步骤3：对每个单元上表面的选定区域进行表面处理,使P型氮化镓的表层的中心区域形成电流阻挡层；步骤4：在每个单元上表面制作P电极,该P电极覆盖整个电流阻挡层及P型氮化镓,完成氮化镓基发光二极管电流阻挡层的制作