Low-temperature electrolytic coloration and spectral property of ammonium alum crystals

Ammonium alum crystals are colored electrolytically using a pointed cathode and a flat anode at low temperatures and under various voltages. SO₃^?, SO₂^? and O₃^? hole-trapped centers are produced in colored ammonium alum crystals. Characteristic absorption bands of SO₃^?, SO₂^? and O₃^? hole-trapped centers are observed in absorption spectra of colored ammonium alum crystals. Production and conversion of hole-trapped centers are explained. Current–time curves for electrolytic coloration of ammonium alum crystal and their relationship with electrolytic coloration process are given.     

Preparation and Mechanical Properties of Fe3Al Nanostructured Intermetallics

Nanostructured Fe₃Al intermetallic compounds were produced by using hydrogen arc plasma method. The transmission electron microscopy experiments showed that the average particle size of the as-synthesized was about 40-nm. The change in hardness of Fe₃Al nanostructured intermetallic compounds with annealing temperatures was observed and evaluated.     

物理教育研究评估

科学的定性及定量评估方法是物理教育研究重要的研究手段.目前国际通用的教育评估测试,根据测试目标的不同,可分为多种类型:学习内容调查、学习态度调查和科学分析能力调查等.我们已将本文中介绍的部分评估测试应用于国际教育研究领域.     

Atomic force microscopy investigation of growth process of organic TCNQ aggregates on SiO2 and mica substrates

<正>Deposition patterns of tetracyanoquinodimethane(TCNQ) molecules on different surfaces are investigated by atomic force microscopy.A homemade physical vapour deposition system allows the better control of molecule deposition. Taking advantage of this system,we investigate TCNQ thin film growth on both SiO_2 and mica surfaces.It is found that dense island patterns form at a high deposition rate,and a unique seahorse-like pattern forms at a low deposition rate.Growth patterns on different substrates suggest that the fractal pattern formation is dominated by molecule-molecule interaction.Finally,a phenomenal "two-branch" model is proposed to simulate the growth process of the seahorse pattern.     

Cs 39D态Rydberg原子Stark光谱的实验研究

本文从理论和实验上对Cs39D态Rydberg原子在弱电场作用下的Stark效应做了详细研究. 理论上利用数值方法计算了Cs原子39D态的Stark结构;实验上,采用两步激发超冷基态原子获得超冷Rydberg原子,通过场电离的方法获得了39D态的Stark光谱,测量获得α^5/2₂,α^5/2₀,α^3/2₂和α^3/2₀相应的极化率分别为：62(7),－146(13), 73(6) 和－106(20) MHz·V^-2cm²,实验结果与理论相符合.     

Integrated modeling of insect flight: From morphology,kinematics to aerodynamics

An integrated and rigorous model for the simulation of insect flapping flight is addressed. The method is very versatile, easily integrating the modeling of realistic wing–body morphology, realistic flapping-wing and body kinematics, and unsteady aerodynamics in insect flight. A morphological model is built based on an effective differential geometric method for reconstructing geometry of and a specific grid generator for the wings and body; and a kinematic model is constructed capable to mimic the realistic wing–body kinematics of flapping flight. A fortified FVM-based NS solver for dynamically moving multi-blocked, overset-grid systems is developed and verified to be self-consistent by a variety of benchmark tests; and evaluation of flapping energetics is established on inertial and aerodynamic forces, torques and powers. Validation of this integrated insect dynamic flight simulator is achieved by comparisons of aerodynamic force-production with measurements in terms of the time-varying and mean lift and drag forces. Results for three typical insect hovering flights (hawkmoth, honeybee and fruitfly) over a wide rang of Reynolds numbers from O(10²) to O(10⁴) demonstrate its feasibility in accurately modeling and quantitatively evaluating the unsteady aerodynamic mechanisms in insect flapping flight.     

基于经验模态分解和小波阈值的冲击信号去噪

冲击信号是非线性的并且容易受到噪声污染。为研究冲击信号去噪的问题,本文针对经验模态分解(Empirical Mode Decomposition,EMD)去噪和小波阈值去噪方法存在的不足,提出了基于EMD的小波阈值去噪方法。单纯的EMD去噪方法会在去除高频噪声的同时压制高频的有效信息。本文将EMD与小波阈值去噪相结合,利用连续均方误差准则确定含噪较多的高频固有模态函数(Intrinsic Mode Function, IMF),对高频IMF分量进行小波阈值去噪,以分离并保留这些分量中的有效信息,同时保持低频IMF分量不变。对模拟数据和实际冲击信号进行去噪处理,结果表明,基于EMD的小波阈值去噪方法的去噪效果优于单纯的EMD去噪方法和小波阈值去噪方法。     

微波消解植物灰分与环境土壤中微量元素的ICP-AES方法研究

应用MDS-2002A犁压力自控密闭微波消解样品制备系统,针对研究样品的特性和共性,进行植物灰分和土壤样品相同微波消解条件的研究实验,并采用电感耦合等离子体原子发射光谱法测定其元素的含量.讨论了混合酸体系、混酸配比、固液比和微波消解时间对于样品制备结果的影响.最终的优选方案为A281C2,即微波程序为工步2,混酸配比为6:2:1:1,混合酸体系为HNO3-HCl-HF-HClO4,最高功率消解时间为10 min的条件下,消解结果最佳.在微波消解最佳条件下,进行了方法准确度实验和测量结果重现性实验,该方法经土壤(GBW07401)和植物(GBW07603)国家标准物质验证,所得测试结果的相对误差均在0.00%～7.14%之间,相对标准偏差均在0.87%～5.25%之间.结果表明,微波消解法处理植物灰分和土壤样品,具有快速、简便、节省试剂、消解完全等特点,测定结果的准确度和精密度令人满意.     

X射线显微CT用于大鼠骨小梁结构分析的研究

应用X射线显微CT(X-μCT)对正常及骨质疏松大鼠的骨小梁结构进行了分析,并与骨组织形态计量法的测量值进行了比较,探讨了X射线光谱技术在骨结构分析中的应用。实验对大鼠骨样品进行X-μCT扫描,扫描条件为 80 kVp,80 μA,360°旋转,帧平均4帧,角度增益 0.4°,分辨率14 μm。三维重建并分析了骨小梁结构,结构参数包括骨体积分数(BV/TV)、骨小梁厚度(Tb.Th)、骨小梁数量(Tb.N)以及骨小梁间隔(Tb.Sp)。结果表明,采用X-μCT分析不同组大鼠的骨小梁结构参数值之间存在显著差异(P<0.05),测定值与传统骨组织形态计量法的测定值显著相关,其中胫骨骨小梁BV/TV,Tb.Th,Tb.N,Tb.Sp的相关系数r分别为0.984,0.960,0.995,0.988,腰椎骨小梁各结构参数的相关系数分别为0.938,0.968,0.877,0.951。因此,X-μCT可以较好地呈现并区分正常骨组织、骨质疏松骨组织以及经雌激素治疗后骨组织的微观结构,可以实现对骨小梁结构参数的分析测定,与骨组织形态计量法相比是一种更精确、立体、快速且无损测量骨微结构和评价骨质量的方法。     

Impact parameter and beam energy dependence for azimuthal asymmetry of direct photons and free protons in intermediate energy heavy-ion collisions

Hard photon emitted from energetic heavy ion collisions is of very interesting since it does not experience the late-stage nuclear interaction, therefore it is useful to explore the early-stage information of matter phase. In this work, we have calculated the impact parameter and beam energy dependence for azimuthal asymmetry, characterized by directed transverse flow parameter F and elliptic asymmetry coeffcient v2, of direct photons and the corresponding free protons in intermediate energy heavy-ion collisions. It is further shown the anti-correlated azimuthal asymmetry between direct photons and free protons.