地震水化前兆的灰色识别

本文研究了水化地震前兆的灰色系统识别方法, 并以北京栏杆市热水井H2浓度动态为例建立了GM(1, 1)滑动识别模型。文中提出了动态前兆识别参数M(t)的概念, 认为动态前兆识别参数M(t)比静态识别指标更有效。用这种识别法进行后验性识别, 提前于内蒙丰镇1981年8月13日5.8级地震前15天识别出发震前兆。以唐山地震前后津2热水井CO2前兆异常识别的失败为反例, 分析了失败的原因, 认为对地震平静期的观测研究是进行水化前兆灰色识别的前提。     

Competitive colorimetric triazophos immunoassay employing magnetic microspheres and multi-labeled gold nanoparticles along with enzymatic signal enhancement

The authors have developed a competitive immunoassay for the model pesticide triazophos (TRIAZ). The method is based on the use of only one monoclonal antibody immobilized on multi-labeled gold nanoparticle (AuNP) probes. The immunoassay uses two sets of probe. The first is a multi-labeled AuNP probe that carries monoclonal antibody (mcAb), single-stranded DNA (ssDNA) and horse radish peroxidase (HRP). The second is a magnetic microparticle (MMP) probe that is obtained by coating MMPs with ovalbumin coupled to TRIAZ. Free TRIAZ and MMP-immobilized TRIAZ compete for binding to the mcAb on the surface of the AuNPs. Because TRIAZ is a rather small molecule, it cannot be bound by two antibodies. The competitive immunoassay overcomes the limitations of small molecule detection using one kind of mcAb only. Sensitive transduction of the immunoreaction is accomplished by enzymatically catalyzed amplified. TRIAZ was quantified by a conventional ELISA and by the immunoassay presented here. Both method are highly sensitive and well reproducible. The new assay has a linear response in the 15 ng L^?1 to 40 μg L^?1 TRIAZ concentration range, and a 14 ng L^?1 limit of detection which make it more sensitive than the ELISA. The recovery rate in case of spiked samples ranges from 78.4 to 105%, and the RSD is <20%. A good correlation was further established between the results of the immunoassay and those of GC-MS analysis.

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Graphical abstract Schematic of a competitive colorimetric triazophos immunoassay employing magnetic microspheres (black color) and multi-labeled gold nanoparticles (red color). The assay overcomes the obstacles in pesticide detection and shows higher sensitivity than the conventional ELISA.

     

Chiral molecular switches based on binaphthalene molecules with anthracene moieties: CD signal due to interchromophoric exciton coupling and modulation of the CD spectrum

By coupling the features of binaphthalene and anthracene, new binaphthalenes with two anthracene moieties were designed and synthesized, aiming at developing chiral molecular switches. A strong CD signal with negative sign due to the interchromophoric exciton coupling was observed for (S)-1 with -(CH2)2 as the linker. This new CD signal became weak and the sign reversed by changing the linker to -(CH2)3 in (S)-2 and -(CH2)6 in (S)-3. For (S)-4 with -(CH2)11 as the linker, no such CD signal was detected. Photodimerization of two anthracene moieties in these binaphthalene molecules can occur. The results show that the CD spectra of (S)-1, (S)-2, (S)-3, and (R)-1 can be reversibly modulated by alternating UV light irradiation and heating. Therefore, chiral molecular switches based on new binaphthalenes with two anthracene moieties are achieved.     

HL—1M装置等离子体电子温度测量

在ＨＬ－１Ｍ装置上用红宝石激光９０ｏ汤姆逊散射对等离子体电子温度进行了测量,建立了激光测量等离子体电子温度的数学模型。开发了用于数据采集和处理的程序,并对实验结果进行了初步讨论和误差分析。     

MXene基单原子催化剂的制备及其在电催化中的应用

单原子催化剂具有高原子利用率、高催化活性和高选择性等优点,兼具了均相催化剂“独立活性位点”和非均相催化剂“易循环利用”的特点,有效解决贵金属昂贵稀少的缺陷。其中载体不仅能影响单原子的稳定性,还影响其电子结构,从而影响催化性能。作为一种新型二维无机材料,MXene具有比表面积大、带隙可调、导电性好和螯合位丰富等特点,是制备单原子催化剂的理想载体材料。本文简要总结了MXene的结构特点,综述了MXene基单原子催化剂的制备策略,并着重介绍了MXene基单原子催化剂在电化学能源转换领域的应用,包括析氢反应、氧电极反应、氮还原反应、二氧化碳还原反应,以及在电池储能方面的应用。最后,总结了当前MXene基单原子催化剂在研究和实用方面所面临的挑战与机遇。     

不同循环加载应力下花岗岩Kaiser效应特征的试验研究

为了更准确地获取花岗岩的Kaiser效应点对应的应力值σAE,利用RMT-100B岩石力学伺服试验机和Micro-Ⅱ Express型声发射监测系统,研究不同循环加载应力σci下岩石Kaiser效应特征.结果表明:相比单次加载,在循环加载作用下,试样的应力-应变曲线在加载初期下凸减弱,压密阶段变短;由于试样的加卸载曲线...     

流化床反应器中Ni/γ-Al2O3催化剂上甲烷部分氧化制合成气

催化甲烷部分氧化(POM)制合成气已成为替代水蒸气重整最有希望的工艺过程之一[1]. 该过程是个温和的放热反应,反应速度非常快,在高空速下可实现高甲烷转化,并且制得的合成气V(H2)/V(CO)=2, 可直接用于合成甲醇及F-T合成烃类、合成二甲醚等后续工业过程. 到目前为止,大部分POM的研究工作在固定床反应器中进行[2～4]. 由于反应速度极快,导致催化剂表面存在热点[2,5], 不仅影响实验的准确性[6,7], 而且工业应用困难. 热点的存在还会导致活性组分Ni的烧结和流失. 在固定床反应器中,催化剂积炭也是导致其活性下降的重要原因[8,9]. Bharadwaj等[10]发现,流化床反应器Rh和Ni催化剂上甲烷转化率高达90%, 反应后催化剂未发现积炭. Santos等[11]曾报道采用流化床催化剂床层几乎可以实现等温分布,而且甲烷转化率接近热力学平衡值, 反应10 h后催化剂表面积炭量仅为0.6%. 本文采用流化床反应器考察了不同反应条件下Ni/γ-Al2O3催化剂上甲烷部分氧化的反应性能,同时对催化剂积炭及稳定性作了初步研究.     

利用汉明距离优选神经网络学习样本

鉴于学习样本对神经网络模型的模式识别性能有很大的影响 ,提出学习样本的选择应与识别模型所利用的特性相结合 ,并利用汉明 (Hamming)距离对用于旋转不变识别的级联模型的学习样本进行优选 ,计算机对三个很相似的飞机模型进行识别 ,识别结果表明对学习样本进行有效的选择不仅可以减少系统的学习训练时间而且可以提高模型的识别能力。     

Molecular Engineering of Star-Shaped Indoline Hole Transport Materials: The Influence of Planarity on the Hole Extraction and Transport Processes

As the key properties of perovskite solar cells (PSCs), the hole extraction and transport capabilities of the hole transport material (HTM) affect the photovoltaic performance of PSCs to a considerable extent, while both capabilities can be adjusted by molecular planarity. Therefore, in this work, the molecular planarity of the HTM is systematically optimized to regulate the hole extraction and transport capabilities. Along with the improvement in planarity, the HTM′s HOMO level is increased, leading to the enhancement of hole extraction capability. Meanwhile, the hole transport capability can also be improved due to the intensification of molecular stacking during the film formation. As a result, the planar HTM achieves a relatively high efficiency of 18.48 %, which is higher than that of spiro-OMeTAD. Accordingly, the molecular planarity presents an important impact on the photovoltaic performance of PSCs, providing us with a promising strategy for further optimization of efficient HTMs.     

Controlled synthesis of urchin-like Bi2S3 via hydrothermal method

The urchin-like Bi₂S₃ nanostructures have been grown by a facile environmentally friendly hydrothermal method. X-ray diffraction (XRD) and Raman spectrum demonstrate that the obtained samples are composed of pure orthorhombic phase Bi₂S₃. Scanning electron microscopy (SEM) images and transmission electron microscopy (TEM) images reveal that it is produced as uniform urchin-like pattern with spherical symmetry. High-resolution (HR) TEM and selected-area electron diffraction (SAED) demonstrate that the nanowires which grow radially from the center of the urchin-like nanostructures toward all directions are single-crystalline and grow along the [001]. It is found that the reaction time, reaction temperature and thiourea (Tu) play key roles for the formation of urchin-like Bi₂S₃ nanostructures. The formation mechanism is ascribed to self-assembly and the intrinsic splitting character of the Bi₂S₃ structure. The urchin-like Bi₂S₃ composed of porous nanorods, solid nanorods and nanowires could be found potential application in optical, catalysts and sensor devices.