用回归分析方法优选有杆泵抽油井的抽汲参数

姚春冬，张树江．用回归分析方法优选有杆泵抽油井的抽汲参数，数理统计与管理，１９９７，１６（１），９～１５．本文根据现场测试数据，建立了抽油机井地面效率、井下功率损失与排量系数的回归公式，以此为基础建立了以系统效率为目标函数的抽油机井抽汲参数优化设计模型，从而提出了一种优选抽油机井抽汲参数的新方法     

Probing the role of metal cations on the aggregation behavior of amyloid β-peptide at a single molecule level by AFM

With the development of nanotechnology, understanding of intermolecular interactions on a single molecule level by atomic force spectroscopy (AFM) has played an important role in molecular biology and biomedical science. In recent years, some research suggested that the presence of metal cations is an important regulator in the processes of misfolding and aggregation of the amyloid β-protein (Aβ), which may be an important etiological factor of Alzheimer’s disease. However, the knowledge on the principle of interactions between Aβ and metal cations at the single molecule level is still poor understood. In this paper, the amyloid β-protein (Aβ) was fabricated on substrate of mixed thiol-modified gold nanoparticles using self-assembled monolayer method and the adhesion force in the longitudinal direction between metal cations and Aβ42 were investigated by AFM. The role of metal ions on Aβ aggregation is discussed from the perspective of single molecular force. The force results showed that the specific adhesion force F _i and the nonspecific force F ₀ between a single Aβ–Aβ pair in control experiment were calculated as 42 ± 3 and 80 pN, respectively. However, F _i between a single Aβ–Aβ pair in the presence of Cu²⁺, Zn²⁺, Ca²⁺ and Al³⁺ increased dramatically to 84 ± 6, 89 ± 3, 73 ± 5, 95 ± 5 pN successively, which indicated that unbinding between Aβ proteins is accelerated in the presence of metal cations. What is more, the imaging results showed that substoichiometric copper cations accelerate the formation of fibrils within 3 days. The combined atomic force spectroscopy and imaging analysis indicate that metal cations play a role in promoting the aggregating behavior of Aβ42.     

Absorption band of Y<Subscript>2</Subscript>O<Subscript>3</Subscript> micro- and nanopowders induced by proton and electron bombardment

A comparative analysis of the structure, phase composition, morphology, and diffuse reflection spectra in the region of 0.2–2.5 μm is carried out. Their changes arising from the bombardment of microand nanopowders of yttrium oxide with 100-keV protons and 100-keV electrons is examined. It is found that the reflectance of the nanopowders in the near-IR (infrared) region is less than that of the micropowders and, upon electron bombardment, their radiation resistance is slightly larger as compared to the micropowders.     

Preparation and properties of an ordered, uniform 0.9 nm Ag array assembled in a nanoporous VSB-1 by a simple soft chemical method

An ordered, homogeneously distributed and uniform 0.9 nm Ag array, which exhibits an unusual UV-vis surface plasmon resonance absorption peak at 355 nm with the largest blue-shift position and controllable intensity, has been successfully prepared by a simple soft chemical approach using the nanoporous VSB-1 as the template.     

(Co,Ni) Se2/C@FeOOH中空笼状纳米结构的自旋调控加速水氧化催化研究

氢气作为一种清洁无污染的可再生能源,可以有效地解决全球能源危机和环境污染问题.低能耗水裂解制氢是公认的未来清洁制氢的有效途径之一.水裂解反应分为阳极上发生的析氧反应(OER)和阴极上发生的析氢反应,由于阳极半反应涉及四电子过程,反应动力学缓慢,进而导致整个水分解产氢效率低下,成为规模化水裂解制氢应用的瓶颈.贵金属Ir基...     

EAST中性束穿透损失分析

中性束注入(NBI )是托卡马克装置四种辅助加热手段(中性束注入、低杂波、离子回旋段波、电子回旋段波)中加热效率最高、物理机制最清楚的一种等离子体加热技术,是国际聚变界公认的最有效的辅助加热手段之一。为了探究EAST-NBI的穿透损失,通过对穿透损失率产生原理的理论分析,设计了具体硬件电路框图和实验方案,并通过实验验证了理论推导的正确性。具体做法首先通过对离子源束斑内中心点热电偶进行定量标定的方法作为穿透损失计算的标准。通过石墨瓦上热电偶单位能量下的温升与标定热电偶的温升之比来对穿透损失率进行计算。实验结果表明在一定的束能范围内,穿透损失率随着注入束能的增加而线性增长,穿透损失率随着等离子体密度增长呈指数衰减。     

EAST中性束注入控制系统设计

中性束注入（NBI）是磁约束核聚变装置等离子体加热和电流驱动的重要手段。依据东方超环（EAST）NBI实验运行特点,设计了基于网络通讯的集散式控制系统。NBI控制系统采用计算机网络技术,按照控制层次分为远程监控层、服务器控制层和现场控制层,三层控制结构易于系统功能扩展与设备升级。一条束线的两个离子源可以独立运行控制,这为EAST第二条束线控制扩展奠定基础。实验表明,NBI控制系统具备了远程监控、连锁保护和数据处理功能,满足了NBI实验运行的自动化和可视化的需求。     

Sn and SnO2-graphene composites as anode materials for lithium-ion batteries

Sn and SnO₂-graphene composites were synthesized using hydrothermal process, followed by annealing in Ar/H₂ atmosphere, and characterized using x-ray diffraction, scanning electron microscopy, and transition electron microscopy. The results indicated that the polycrystalline metallic Sn forms nanospheres with a diameter of 100?～?300 nm, while the SnO₂ nanoparticles are much smaller with a size below 15 nm, which adsorb tightly on the surface of graphene sheets. The Sn and SnO₂-gaphene composites showed good electrochemical performance. After 55 charging/discharging cycles, the capacity remains above 440 mAh/g at a cycling rate of 400 mA/g and the coulombic efficiency is 99.1 %. The good electrochemical properties of the composites are partially contributed to the graphene component with good mechanical flexibility and electrical conductivity, which is an excellent carbon matrix for dispersing the Sn and SnO₂ nanostructures and provides the electron transport pathways as well.     

Label-free visual detection of nucleic acids in biological samples with single-base mismatch detection capability

We have combined an allosteric molecular beacon for target recognition and guanine-rich DNAzyme for signal amplification to develop a new platform for visual detection of nucleic acids with single-base mismatch detection capability. The fully DNA-structured platform can undergo color change in response to target DNA/RNA, which enables sensitive and selective visual detection in biological samples.     

分部优化正则化在近场声全息技术中的应用

在基于等效源法近场声全息技术的基础上,对稳定重建过程不适定性的正则化技术进行深入研究。为改善正则化效果,综合考虑Tikhonov正则化和截断奇异值法,提出一种新的分部优化正则化技术。该技术兼取了两种方法的优点,比Tikhonov正则化稳定,避免了过滤波等正则化失效的情况;比截断奇异值法精度高,包含了更多的细节信息。通过对简支板的数值仿真,分别和Tikhonov正则化和截断奇异值法进行了比较,说明了本文所提方法稳定性较好和精度较高的优点。最后通过实验研究进一步证明了本文方法的有效性和正确性。