Development and application of absolute quantitative detection by duplex chamber-based digital PCR of genetically modified maize events without pretreatment steps

The possibility of the absolute quantitation of GMO events by digital PCR was recently reported. However, most absolute quantitation methods based on the digital PCR required pretreatment steps. Meanwhile, singleplex detection could not meet the demand of the absolute quantitation of GMO events that is based on the ratio of foreign fragments and reference genes. Thus, to promote the absolute quantitative detection of different GMO events by digital PCR, we developed a quantitative detection method based on duplex digital PCR without pretreatment. Moreover, we tested 7 GMO events in our study to evaluate the fitness of our method. The optimized combination of foreign and reference primers, limit of quantitation (LOQ), limit of detection (LOD) and specificity were validated. The results showed that the LOQ of our method for different GMO events was 0.5%, while the LOD is 0.1%. Additionally, we found that duplex digital PCR could achieve the detection results with lower RSD compared with singleplex digital PCR. In summary, the duplex digital PCR detection system is a simple and stable way to achieve the absolute quantitation of different GMO events. Moreover, the LOQ and LOD indicated that this method is suitable for the daily detection and quantitation of GMO events.     

松花江冰下声学试验技术研究

北极区域极具战略意义与商业价值,随着各国的广泛关注,针对北极地区开展的科考科研活动逐渐增多。其中北极海域的相关研究尤为重要,特别是北极水声学,是保障北极军事存在以及正常科考科研活动的重要支撑。课题组于2015年1月在哈尔滨松花江进行了冰下声学试验,主要内容包括冰下信道测试、冰层散射系数测量以及冰下水声通信试验,实现了冰下半波导现象的初步观测、冰层前向散射系数的测量、基于能量检测器的低信噪比扩频通信、基于时反镜判决反馈均衡技术的高速水声通信以及冰下12用户多址水声通信等内容。本文对本次冰下声学试验情况进行介绍,并给出了相应的试验结果及经验总结。     

一种钆硼酸盐Rb2LiGdB2O6的结构、合成及光学性质

在Rb2 CO3-Li2 CO3-Gd2 O3-H3 BO3体系中,用自发结晶的方法获得了一种钆硼酸盐Rb2 LiGdB2 O6(RLGBO)单晶,同时,用固相合成法获得了RLGBO粉末多晶.单晶结构解析表明,RLGBO属于正交晶系,Pbcm空间群,晶胞参数a=7.0259(3)?,b=9.6103(4)?,c=10.0562(4)?和z=4.热学性质表明,RLGBO在840℃下保持良好的热稳定性.在RLGBO中分别掺杂2;的Ce3+,80;的Eu3+和50;的Tb3+之后,其结构不会发生改变.在紫外光及近紫外光激发下,RLGBO:Ce3+,RLGBO:Eu3+和RLGBO:Tb3+可分别发射蓝光,红光和绿光.结果表明,RLGBO化合物可作为发光物质的基质材料.     

纳氏试剂分光光度法测定铝灰渣浸出液中的氨氮含量

随着水土资源环境日益恶化,监测氨氮量对水土的污染程度也备受关注。为了准确测定铝灰渣浸出液中的氨氮量,实验对振荡方法、振荡时间、固液比、试液过滤方式、纳氏试剂加入量以及测定干扰因素进行了研究。确定了以翻转振荡为前处理方式,最佳振荡时间为14 h,固液比为1:10,最佳纳氏试剂加入量为1.0 mL,通过改善过滤方式,降低了空白值。由实验结果可知：在试验范围内,F^-对氨氮量的测定不产生干扰;对于浸出液中Cl^-、Al³⁺和Ca²⁺浓度高的样品,可通过移取稀释液2.00 mL,加入1.0 mL酒石酸钾钠溶液(500 g/L),即可消除其干扰。运用纳氏试剂分光光度法测定铝灰渣浸出液中的氨氮量,得到氨氮标准曲线线性相关系数为0.9998,方法检出限为0.39 mg.L^-1,RSD(n=6)<5%,回收率在94.7%～105%之间。本方法简单快速,精密度高,且具有较低的检出限,适用于大批量铝灰铝渣等固体废物浸出液中氨氮量的测定。     

介孔钯-硼合金纳米颗粒的制备和甲醇氧化电催化性能北大核心CSCD

合金化可以调节贵金属纳米材料的物理化学性质,从而显著提升它们的电催化性能。尽管合金化在过去的20多年里已取得诸多成果,但是如何充分发挥纳米合金的组分优势仍需深入的探究。本研究通过一步溶液相合成法实现了类金属硼(B)合金化的钯基介孔纳米催化剂材料的合成,同时探究了B原子的组分优势和介孔形貌的结构优势在碱性介质中电化学甲醇氧化反应(MOR)的协同作用。最优PdCuB介孔纳米催化剂表现出优异的电化学MOR活性和稳定性。机理研究表明,优异的催化活性源于B原子在Pd基介孔纳米催化剂中的积极协同作用;该协同作用通过电子效应(改变Pd的表面电子结构从而减弱CO基中间体的吸附)和双功能效应(促进OH_(2)的吸附从而氧化CO基中间体)在动力学上加速了有毒CO基中间体的去除(提高甲醇氧化的决速步骤)。同时,B原子的间隙插入和介孔结构抑制了物理奥斯特瓦尔德(Ostwald)熟化过程,显著增加了催化剂的稳定性。     

微生物肥料对西红花生长及代谢物的影响

在大田条件下,研究了重茬净、微生物菌剂、锦能菌宝、自制活性生物肥料4种不同微生物肥料对西红花产量、代谢物和根际微生物生态的影响。结果表明,与对照组相比,施用微生物肥料后,根际土壤中好酸性的细菌呈减少趋势,而嗜中性或碱性的细菌呈增加趋势,4种微生物肥料均能提高西红花有效球比例,表明增施微生物肥料具有缓解西红花连作障碍的功效。同时,增施重茬净、微生物菌剂、锦能菌宝和自制活性生物肥料分别引起2,3,3和13种代谢物含量上调和2,3,2和4种代谢物含量下调。     

A Simple,Low-cost Method to Fabricate Drag-reducing Coatings on a Macroscopic Model Ship

A low-cost method was used to fabricate superhydrophobic coatings on a macroscopic model ship and the drag-reducing effect was investigated at both low and high speed. Hierarchical structures of the superhydrophobic copper coatings were characterized by means of scanning electron microscopy(SEM) and X-ray diffraction(XRD). Drag coefficient tests on surfaces with different wettability(superhydrophilic, hydrophilic, hydrophobic and superhydrophobic surfaces) showed that the as-prepared superhydrophobic surface exhibited a high remarkable drag reduction of 81% at a low speed of 1 mm/s. In the drag-reducing tests with model ship, the superhydrophobic coatings also exhibited around 16% drag reduction at a velocity of 0.3 m/s.     

Generalized coarse-grained model based on point multipole and Gay-Berne potentials

This paper presents a general coarse-grained molecular mechanics model based on electric point multipole expansion and Gay-Berne [J. Chem. Phys. 74, 3316 (1981)] potential. Coarse graining of van der Waals potential is achieved by treating molecules as soft uniaxial ellipsoids interacting via a generalized anisotropic Gay-Berne function. The charge distribution is represented by point multipole expansion, including point charge, dipole, and quadrupole moments placed at the center of mass. The Gay-Berne and point multipole potentials are combined in the local reference frame defined by the inertial frame of the all-atom counterpart. The coarse-grained model has been applied to rigid-body molecular dynamics simulations of molecular liquids including benzene and methanol. The computational efficiency is improved by several orders of magnitude, while the results are in reasonable agreement with all-atom models and experimental data. We also discuss the implications of using point multipole for polar molecules capable of hydrogen bonding and the applicability of this model to a broad range of molecular systems including highly charged biopolymers.     

聚苯乙烯荧光乳液的制备及其性能研究

为了实现萘酰亚胺水性化以及提高与纸张的结合性,通过乳液聚合法制备了聚苯乙烯荧光乳液,并对其合成条件进行了优化。通过红外、凝胶渗透色谱法确定其结构;利用紫外、荧光光谱测定其光学性能;采用扫描电镜和透射电镜对其形貌进行了观测。通过计算得出其荧光量子产率为78.57%。聚合物涂布于纸张表面后,初始白度增大了8.19%（ISO）。在紫外老化箱老化48 h后,涂有聚合物的纸张的白度分别比空白纸和涂有小分子荧光增白剂的纸张下降了3.68%（ISO）和3.16%（ISO）,说明所制得的聚合物乳液与纸张结合性好,具有一定的增白及返黄抑制作用。     

高效氟代联蒽类深蓝光材料的合成及OLED性能

为了开发新型多功能的蓝光电致发光材料与器件,设计并合成了一系列氟取代联蒽类材料(BAnFs),通过改变吸电子基团的取代模式,进而调节其光物理性能、热稳定性和能级.以CBP为主体、BAnFs为掺杂的器件表现出高效的深蓝光发光性能,对应的色坐标为CIE (0.15, 0.08),特别是对BAn-(3,5)-CF3器件的电流效率为3.05 cd/A,最大外量子效率(EQE)高达5.02;.同时BAnFs材料可作为高性能的蓝光主体材料,其EQE为3.56;~5.43;.因此,BAnFs可作为新型高性能的多功能蓝光发光材料.