Polarized spin transport in mesoscopic quantum rings with electron--phonon and Rashba spin--orbit coupling

The influence of electron--phonon (EP) scattering on spin polarization of current output from a mesoscopic ring with Rashba spin--orbit (SO) interaction is numerically investigated. There are three leads connecting to the ring at different positions; unpolarized current is injected to one of them, and the other two are output channels with different bias voltages. The spin polarization of current in the outgoing leads shows oscillations as a function of EP coupling strength owing to the quantum interference of EP states in the ring region. As temperature increases, the oscillations are evidently suppressed, implying decoherence of the EP states. The simulation shows that the magnitude of polarized current is sensitive to the location of the lead. The polarized current depends on the connecting position of the lead in a complicated way due to the spin-sensitive quantum interference effects caused by different phases accumulated by transmitting electrons with opposite spin states along different paths.     

汽车制动噪声的研究

近年来,随着人们环保意识的增强,汽车制动产生的噪声污染备受关注.本文分析了汽车制动噪声产生的特点,并从实验和理论两方面系统回顾了制动噪声的研究工作,重点对各种制动噪声的机理进行了分析和评述.最后,指出目前制动噪声研究工作的不足,并对未来的研究工作提出了一些展望和建议.     

分子印迹技术和荧光分析技术在爆炸物检测中的应用*

爆炸品危害社会安定、国家安全,引起国际社会的关注。开发爆炸品的在线监测技术成为当今热点研究领域之一。爆炸物的种类多种多样,它们的检测方法也各不相同。本文简要地回顾了爆炸物的常规检测方法,介绍了爆炸物的新颖检测技术,重点介绍了分子印迹技术和荧光分析技术在爆炸物检测中的应用,总结了分子印迹聚合物和荧光共轭聚合物检测爆炸物的特点,并对它们的发展趋势进行了展望。     

考虑自重载荷作用的连续体结构拓扑优化

针对自重载荷作用下连续体结构拓扑优化中常遇到的柔顺度随单元密度变化的非单调性、非有效的材料体积约束和材料低密度区出现的``附属'效应等主要困难,提出了RAMP材料插值模型和平均敏度过滤技术相结合的求解策略,并采用MMA方法进行了优化求解. 研究了惩罚因子的选择对最优拓扑以及材料体积约束的影响. 结果表明,合理增大RAMP材料模型中惩罚因子(例如取值达到20.0), 可使材料体积约束达到有效约束. 此外,通过与Sigmund提出的敏度过滤技术比较表明,当引入平均敏度过滤技术时,结果0/1化程度较Sigmund的敏度技术高,可获得清晰的黑白拓扑.      

STUDY ON MECHANICAL INTERACTIONS BETWEEN SINGLE CARDIAC MYOCYTE AND ELASTIC SUBSTRATE

Quantitative investigation on mechanical characteristics of cardiac myocytes has important physiological significance. Based on elastic substrate technique, this paper develops a set of algorithms for high-efficiency cellular traction recovery. By applying a gradient-based digital image correlation method to track randomly distributed fluorescence microbeads on the deformed substrate induced by single cardiac myocyte, high-resolution substrate displacement field can readily be obtained. By using a numerical algorithm based on the integral Boussinesq solution, cell-substrate tractions are reconstructed in a stable and reliable manner. Finally, spatiotemporal dynamics of a single cardiac myocyte is investigated as it adheres to a polyacrylamide elastic substrate.     

发光二极管诱导荧光检测器*

发光二极管诱导荧光检测器（LED-IF）是近十年来发展起来的一种微型化荧光检测器,在流动注射、毛细管液相色谱、毛细管电泳及芯片电泳等微流动分析系统中具有广泛的应用。本文讨论了LED-IF的4种光学结构,并对其主要器件,包括光源、滤光片、透镜、光纤、光电检测器以及检测池作了详细讨论,还介绍了LED-IF与其它技术的联用及其在生物、医药和环境样品检测中的应用,对未来的发展趋势作了展望。     

Bubble generation and transport in a microfluidic device with high aspect ratio

Bubble generation and transport in a micro-device composed of a micro-T-junction and a following serpentine micro-channel was experimentally investigated. It has a rectangular cross-sectional with an aspect ratio of 7.425. Air and water were used as gas and liquid, respectively. Mixtures of water–glycerol and water–Tween-20 were used to study the effects of liquid viscosity and surface tension. Compared with previous T-junction bubble generation, the liquid and gas inlets orientation was switched in this work. The continuous flow was driven from the perpendicular channel and the dispersion flow was from the main channel. It shows that the break-up process has three periodic steps under certain operating conditions. The dimensionless bubble length L/w in the micro-channel with high aspect ratio is much larger than that in square microchannels. A correlation is proposed to correlate L/w with liquid flow rate J_L, gas flow rate J_G, and liquid viscosity μ_L. Surface tension σ can change the bubble shape but almost does not affect the bubble length in this fast break-up process. Additionally, a long bubble may be broken up at the corners at the same time because the locations of gas and liquid are exchanged relative to the concave and convex portions of an elbow after a turn which may result in the change of fluid velocities and gas–liquid pressure drop.     

Preparation of CuInS2 Thin Film Using Sulfides Nanoparticle Precursor Ink

A low cost spin coating route of fabricating CuInS₂ polycrystalline thin films by reactive sin-tering method was put forward. The ink for spin coating was optimized by pre-reducing the precursor powders in hydrogen, which turned the nanoparticle precursor powders from mixed sulfides into a mixture of CuInS₂ and Cu-In metal alloys. The results of scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, and Raman spectra showed that this optimization could highly improve the performance of CuInS₂ polycrystalline thin films, including higher packing density, less impurity phases, and better quality. The en-ergy gap of optimized CuInS₂ thin film was determined to be about 1.45 eV by absorption spectroscopy measurement.     

Influence of local environment on the intensity of the localized surface plasmon polariton of Ag nanoparticles

A combined Ag nanoparticle with an insulating or conductive layer structure has been designed for molecular detection using surface enhanced Raman scattering microscopy. Optical absorption studies revealed localized surface plasmon resonance, which shows regular red shift with increasing environmental dielectric constant. With the combined structure of surface enhanced Raman scattering substrates and rhodamine 6G as a test molecule, the results in this paper show that the absorption has a linear relationship with the local electromagnetic field for insulating substrates, and the electrical property of the substrate has a non-negligible effect on the intensity of the local electromagnetic field and hence the Raman enhancement.     

Viscoelastic measurement of complex fluids using forced oscillating torsion resonator with continuously varying frequency capability

Traditional torsional resonators, often obtaining the viscoelastic moduli of complex fluids only at one or several given discrete frequencies, lack the continuously varying frequency capability. This is an obvious disadvantage of the traditional torsional resonator technique. This paper presents an improved strategy, based on our previous discrete-frequency-measuring method (Wang et al., J Rheol 52:999–1011, 2008), to overcome such restriction and thus accomplish the continuously varying frequency capability of the traditional torsional resonator for measuring the viscoelastic properties of complex fluids. The feasibility of this strategy is demonstrated with the Newtonian fluids (several water–glycerol solutions) of viscosities varying from 10 to 1,400 cp by using our homemade torsion resonator apparatus in the 10 ~ 2,500 rad/s frequency range (continuous frequencies). Some results for typical viscoelastic polymers (two polyethylene oxide (PEO) aqueous solutions) are also given. Additionally, a comparison of the PEO results is made with the common rheometer technique. It is demonstrated that this improved strategy could enable the traditional torsional resonators, with one oscillating resonance mode, to work as the microrheological technique and the common rheometer technique in the continuous frequency range.