应用实时定量PCR技术检测秦皇岛近岸海域褐潮原因种——抑食金球藻(Aureococcus anophagefferens)

Aureococcus anophagefferens, a small pelagophyte algae, has caused brown tide blooms in coastal waters of Qinhuangdao in recent years, presenting significant negative impacts on the shellfish mariculture industry. Under standard light microscopy, it is visually indistinguishable from other small algae in field samples due to its extremely small size. In this study, quantitative polymerase chain reaction(q PCR) based on 18 S r DNA sequences was developed and used to detect and enumerate A. anophagefferens. A linear regression(R2 = 0.91) was generated based on cycle thresholds value(Ct) versus known concentrations of A. anophagefferens. Twenty-two field samples collected in coastal waters of Qinhuangdao were subjected to DNA extraction and then analyzed using q PCR. Results showed that A. anophagefferens had a wide distribution in coastal waters along Qinhuangdao. Elevated A. anophagefferens abundance, category 3 brown tide blooms(200 000 cells/m L) occurred at Dongshan Beach and Tiger-stone Beach in August in 2013. In shellfish mariculture areas along coastal waters of Qinhuangdao, 4 stations had category 3 blooms, and 6 stations had category 2 blooms(35 000–200 000 cells/m L) in August and all stations had category 1 blooms(0 to ≤35 000 cells/m L) in October. Quantitative PCR allows for detection of A. anophagefferens cells at low levels in filed samples, which is essential to effective management and prediction of brown tide blooms.     

有效群体大小对蛤仔F1生长和存活影响

对不同有效群体大小(Ne=2、4、8、16、32、200)的蛤仔F1代生长和存活性状进行了比较。结果表明:浮游期,各试验组幼虫壳长均未表现出显著性差异(P0.05),实验组Ne=200的存活率低于其他各实验组,并随着日龄的增长,差异越来越显著;稚贝期,各实验组的壳长和存活率的变化规律和浮游期基本一致。对壳长变异情况分析表明,浮游期,随着群体有效含量的增大,子代开始出现小型个体和大型个体,壳长分布变异逐渐明显;稚贝期,各试验组组内壳长变异进一步加剧,除Ne=2试验组稚贝壳长介于400μm和600μm之间外,其他各试验组均出现明显的小型和大型个体,表现为有效群体越大,组内稚贝壳长变异越为明显。     

MPI环境下基于边界校正方法的海洋模型的并行化

基于区域分解技术,设计了一种针对海洋模型的边界校正方法,该方法不需要对原有海洋模型进行较大改动,只需要利用消息传递接口(message passing interface,MPI)编写子区域间的数据传输模块,即可实现原有海洋模型的并行化。相对于重新开发并行系统,该方法能够较快把原有模型的串行解决方案转化为并行解决方案,并且并行化后的海洋模型能够获得较高的加速比。     

深水立管设计标准中内波作用的分析与探讨

深水立管的设计、建造以及安装都必须依据相关规范进行,中国当前尚未出台专门针对立管设计的相关标准,现阶段还是以参考国外规范为主。本文首先对立管设计、安装中涉及的相关规范和工业标准进行介绍,论述当前国外API、ABS和DNV设计规范中关于深水立管环境条件及其载荷的相关规定,然后针对中国南海等海域普遍存在的内波现象,分析了内波尤其是内孤立波对顶张力立管的影响,结果表明,内孤立波会引起立管较大的位移以及较高的应力幅值,需要在设计分析中加以考虑。最后对中国在引入API、ABS和DNV等相关规范设计深水立管时提出相应的建议,以期为南海海域油气开发中立管的设计提供参考。     

河北省近海有害藻华灾害分级、时空分布和优势藻华生物变化特征

为研究1989—2013年河北省近海有害藻华灾害分级、时空分布和优势肇事生物变化特征,对河北省近海累计58次有害藻华记录的发生时间、位置与范围、面积和优势有害藻华生物种类进行了统计分析。结果表明:小型(面积0~100 km2)、中型(100~1 000 km2)、大型(≥1 000 km2)和面积不详的有害藻华中,小型藻华为多发性藻华,发生次数占全省海域累计发生次数的60.35%;5-8月份是藻华多发期,发生次数占累计发生次数的86.21%;2000年后藻华发生频率大增,由原来年均发生1次演变为年均发生4次;秦皇岛海域发生藻华次数最多,占全省海域累计发生次数的57.14%,沧州海域次之,唐山海域最少;秦皇岛海域发生藻华累计面积最大,占全省海域累计发生面积的64.25%,沧州海域次之,唐山海域最小。河北省优势海洋有害藻华生物共计15种,易发性藻华生物夜光藻Noctiluca scintillans引发藻华次数最多,占全省海域累计发生次数的44.83%,2009年前是河北省近海最主要的藻华肇事生物;高发性藻华生物抑食金球藻Aureococcus anophagefferens引发有害藻华累计面积最大,占全省海域累计发生面积的55.57%,2009年后该藻和夜光藻共同成为河北省近海优势藻华肇事生物。     

Chemical spots on the surface of the strongly magnetic Herbig Ae star HD 101412

Due to the knowledge of the rotation period and the presence of a rather strong surface magnetic field, the sharp‐lined young Herbig Ae star HD 101412 with a rotation period of 42 d has become one of the most well‐studied targets among the Herbig Ae stars. High‐resolution HARPS polarimetric spectra of HD 101412 were recently obtained on seven different epochs. Our study of the spectral variability over the part of the rotation cycle covered by HARPS observations reveals that the line profiles of the elements Mg, Si, Ca, Ti, Cr, Mn, Fe, and Sr are clearly variable while He exhibits variability that is opposite to the behaviour of the other elements studied. Since classical Ap stars usually show a relationship between the magnetic field geometry and the distribution of element spots, we used in our magnetic field measurements different line samples belonging to the three elements with the most numerous spectral lines, Ti, Cr, and Fe. Over the time interval covered by the available spectra, the longitudinal magnetic field changes sign from negative to positive polarity. The distribution of field values obtained using Ti, Cr, and Fe lines is, however, completely different compared to the magnetic field values determined in previous low‐resolution FORS 2 measurements, where hydrogen Balmer lines are the main contributors to the magnetic field measurements, indicating the presence of concentration of the studied iron‐peak elements in the region of the magnetic equator. Further, we discuss the potential role of contamination by the surrounding warm circumstellar matter in the appearance of Zeeman features obtained using Ti lines. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

基于模糊评判的数控机床零部件制造工艺FMECA研究

以数控机床零部件的制造工艺为研究对象,对其实施改进的制造工艺FMECA,通过梯形模糊数评判的方法确定出工艺FMECA中风险优先数的排序,利用模糊综合评判方法确定出工艺系统的风险等级,有效地找出薄弱工艺环节并采取改进措施,从而提高数控机床零部件制造工艺可靠性.     

Influence of Ohmic diffusion on the excitation and dynamics of MRI

In this paper we make an effort to understand the interaction of turbulence generated by the magnetorotational instability (MRI) with turbulence from other sources, such as supernova explosions (SNe) in galactic disks. First we perform a linear stability analysis (LSA) of non‐ideal MRI to derive the limiting value of Ohmic diffusion that is needed to inhibit the growth of the instability for different types of rotation laws. With the help of a simple analytical expression derived under first‐order smoothing approximation (FOSA), an estimate of the limiting turbulence level and hence the turbulent diffusion needed to damp the MRI is derived. Secondly, we perform numerical simulations in local cubes of isothermal nonstratified gas with external forcing of varying strength to see whether the linear result holds for more complex systems. Purely hydrodynamic calculations with forcing, rotation and shear are made for reference purposes, and as expected, non‐zero Reynolds stresses are found. In the magnetohydrodynamic calculations, therefore, the total stresses generated are a sum of the forcing and MRI contributions. To separate these contributions, we perform reference runs with MRI‐stable shear profiles (angular velocity increasing outwards), which suggest that the MRI‐generated stresses indeed become strongly suppressed as function of the forcing. The Maxwell to Reynolds stress ratio is observed to decrease by an order of magnitude as the turbulence level due to external forcing exceeds the predicted limiting value, which we interpret as a sign of MRI suppression. Finally, we apply these results to estimate the limiting radius inside of which the SN activity can suppress the MRI, arriving at a value of 14 kpc (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)