Pressure dependence of the radial breathing mode of carbon nanotubes: the effect of fluid adsorption

The pressure dependence of shifts in the vibrational modes of individual carbon nanotubes is strongly affected by the nature of the pressure transmitting medium as a result of adsorption at the nanotube surface. The adsorbate is treated as an elastic shell which couples with the radial breathing mode (RBM) of the nanotube via van der Waal interactions. Using analytical methods as well as molecular simulation, we observe a low frequency breathing mode for the adsorbed fluid at approximately 50 cm-1, as well as diameter dependent upshifts in the RBM frequency with pressure, suggesting metallic nanotubes may wet more than semiconducting ones.     

Factorization of discontinuities of multi-Regge amplitudes

It is shown that an arbitrary discontinuity of an arbitrary multi-Regge amplitude factorizes in a large class of models which encompasses the dual resonance model. It is argued that multiple discontinuities also factorize and that the factorization of discontinuities is expexted to hold on very general grounds as a result of the singularity structure of multiparticle amplitudes. These results allow the full amplitude as well as its discontinuities to be written as a product of Regge propagators, single-, double- and triple-Regge vertices and their discontinuities.     

Propulsion of a molecular machine by asymmetric distribution of reaction products

A simple model for the reaction-driven propulsion of a small device is proposed as a model for (part of) a molecular machine in aqueous media. The motion of the device is driven by an asymmetric distribution of reaction products. The propulsive velocity of the device is calculated as well as the scale of the velocity fluctuations. The effects of hydrodynamic flow as well as a number of different scenarios for the kinetics of the reaction are addressed.     

On the Domain of Applicability of General Relativity

We consider the domain of applicability of general relativity (GR), as a classical theory of gravity, by considering its applications to a variety of settings of physical interest as well as its relationship with real observations. We argue that, as it stands, GR is deficient whether it is treated as a microscopic or a macroscopic theory of gravity. We briefly discuss some recent attempts at removing this shortcoming through the construction of a macroscopic theory of gravity. We point out that such macroscopic extensions of GR are likely to be nonunique and involve non-Riemannian geometrical frameworks.     

距离选通技术对后向散射抑制作用的理论分析

 从辐射度学的基本理论出发，建立了单CCD像元的距离选通激光主动成像模型。而后考虑成像质量，借助单CCD像元信噪比和图像均方差误差两个指标，阐明了距离选通技术是抑制后向散射、增大成像距离、提高图像质量的有效手段。最后从模型出发，导出了距离选通技术在激光主动成像中应用时一些关键参数的选取原则:(1) 尽可能减小激光脉冲宽度，以克服后向散射的影响；（2） 要能够达到尽可能远的观测距离，在激光功率一定的条件下，激光占空比越大越好；（3）在激光满足一定条件的情况下，脉冲频率越高越好。     

Aspects of organic chemistry of fullerenes

Successive additions to [60]fullerene show a remarkable degree of regioselectivity. Two characteristic examples of additions, namely nucleophilic cyclopropanations of 6-6 double bonds as well as formations of 5–6 bridged open azafulleroids, have been systematically investigated by analytical, spectroscopic as well as by computational methods. Regioselective additions to activated positions within the carbon framework of fullerene derivatives are the key steps for both controlled ring opening of the fullerene core and the synthesis of heterofullerenes.     

近红外光谱定性分析中的特征波长筛选研究

提出了一种以样品光谱类间相关系数之和最小为准则进行光谱波长逐步筛选的方法(stepwise selection basing on minimum sum of correlation coefficients, SMCC),以类间距离与类内距离和的比值最大化(符合分析者主观预期目标)作为定性分析中特征波长筛选效果的评价依据,并使用红塔集团提供的2012年17种不同类型工业分级烟叶作为试验样品,以验证筛选方法的有效性。研究表明,采用CO1分级烟叶光谱作为参照类别,筛选出10个特征波长点：采用特征波长计算得到的类内欧氏距离的平均值为采用全部波长计算得到的平均值的1.69倍,采用特征波长计算得到的类间欧氏距离的平均值为采用全部波长计算得到的平均值的3.70倍,采用特征波长计算得到的类间欧氏距离与类内欧氏距离和的比值的平均值为采用全部波长计算得到的平均值的2.21倍。特征波长的类间与类内欧氏距离和的比值增大,说明筛选出来的特征波长能更加有效的表达不同类间的远近关系以及同一类内的离散度,SMCC算法是一种有效的、可应用于近红外光谱定性分析中的特征波长筛选方法。     

鲁米诺化学发光法测定食品中的二氧化硫残留量

建立了一种测定食品中二氧化硫残留量的方法。以鲁米诺作为发光剂,空气中的氧气作为氧化剂,亚硫酸根作为敏化剂,硫酸钴作为鲁米诺-空气-亚硫酸根离子化学发光体系的催化剂,通过测定加入亚硫酸盐溶液前后体系的发光总强度的变化,可确定亚硫酸盐的浓度。应用该方法可准确测定干果干菜等食品中二氧化硫残留量。     

Multivariate analysis of dynamical processes

The analysis of multi-dimensional biomedical systems requires analysis techniques, which are able to deal with multivariate data consisting of both time series as well as point processes. Univariate and bivariate analysis techniques in the frequency domain for time series and point processes are established and investigated, although the number of investigations is strongly biased towards time series. Actual multivariate techniques for time series or hybrids of time series and point processes are scarcely addressed. Here, we present spectral analysis techniques which are able to analyse point processes as well as time series. Thereby, univariate, bivariate as well as multivariate techniques are discussed. Applications to simulated as well as real-world data reveal the abilities of the proposed techniques.     

掺杂MgB_2体系超导电性的一个判据

提出一个计算原子半径差和电负性差的方法,研究了原子半径差Δd和电负性差Δe及它们之比△d/△e与掺杂MgB2体系超导转变温度Tc的关系,发现三者都与转变温度有良好的规律性,对它们进行数值模拟都获得开口向下的抛物线关系。由此,提出用原子半径差、电负性差、及它们之比△d/△e作为提高掺杂二硼化镁超导电性的一个新依据。     

Analysis of the informativeness of polarization and nephelometric measurements in diagnostics of the microphysical parameters of erythrocytes

Regression relations are found between the microphysical parameters (MPPs) of human blood erythrocytes and the angular coefficients of linear polarization P(??), as well as between the MPPs of erythrocytes and angular coefficients of linear polarization P(??) together with the directional scattering coefficients ??(??). The efficiency of using these regression relations for determining the MPPs of erythrocytes is estimated. It is shown that the involvement of polarization measurements allows one to reduce the error in the retrieval of MPPs, as well as of the size and volume distribution functions, to ??3%.     

Real-time observation of structural and orientational transitions during growth of organic thin films

We study kinetically controlled orientational and structural transitions of molecular thin films during growth in situ and in real time, using diindenoperylene (DIP) as an example. By time-resolved surface-sensitive x-ray scattering (out of plane and in plane), we follow the organic molecular beam deposition of DIP on silicon oxide, on stepped sapphire, and on rubrene as an organic model surface. We identify transitions for the few-monolayer (ML) regime, as well as for thick (several 10's of ML) films. We show that the differences in the interaction of DIP with the substrate change the thickness as well as temperature range of the transitions, which include (transient) strain, subtle changes of the orientation, as well as complete reorientation. These effects should be considered rather general features of the growth of organics, which, with its orientational degrees of freedom, is qualitatively different from growth of inorganics.     

利用神经网络提高编码器精度的方法

介绍了编码器误差的构成及特点，针对系统误差的分布规律与特点提出了基于神经网络的误差修正方法。采用非线性逼近精度较高的径向基函数神经网络，以采样点的角度值作为网络的输人样本，以高精度检测编码器的检测值作为学习目标建立了误差修正模型。实验结果表明，采用此种方法可将编码器的精度提高至原来的3倍以上，可有效地改善编码器的系统精度。     

Effect of two asymmetries on current of a Brownian particle

A Brownian particle in an asymmetric periodic potential and subjected to an asymmetric dichotomous noise was investigated. In the frame of Fokker-Planck equation, exact expression of current of the system was derived. By means of numerical calculations, the results indicate that: (i) as the symmetry of either potential or noise is broken, a steady current will form; (ii) as the two symmetries are broken simultaneously, the current does not always appear, dependent on values of symmetric parameters of the potential and the noise; (iii) the current exhibits non-monotonic behavior as a function of symmetric parameter of the potential, while monotonic behavior as a function of symmetric parameter of the noise; (iv) in the case the potential symmetry is not broken seriously, the current is greatly influenced on by the noise symmetric parameter; (v) absolute values of the current as a function of height of potential barrier first increase then approach to saturation as the spatial potential is symmetric, while varies monotonically as the dichotomous noise is symmetric. In addition, the planes of the two symmetric parameters, which determine directions of the current, are drawn.     

Specific features of the radiative relaxation of excited states of polymethine dyes of different ionicity in films of photoconductive and nonphotoconductive polymers

The spectral and luminescent properties of film composites based on photoconductive poly-N-epoxipropylcarbazole and nonphotoconductive polyvinylbutyral with admixtures of cationic and anionic polymethine dyes, as well as the effect of an external magnetic field on these properties, are studied. It is found that the magnetic field affects the intensity and kinetics of the delayed fluorescence and recombination luminescence of the cationic dye in photoconductive films. This is explained by specific features of photogeneration of charge pairs, namely, by the participation of the singlet and triplet excited states of dye molecules in this process, as well as by the singlet-triplet conversion in dye molecules and photogenerated charge pairs.     

Effects of high-energy ultrasound on the functional properties of proteins

In recent years, high-energy ultrasound has been used as an alternative to improve the functional properties of various proteins, such as from milk, eggs, soy and poultry. The benefits of implementing this technology depend on the inherent characteristics of the protein source and the intensity and amplitude of the ultrasound, as well as on the pH, temperature, ionic strength, time, and all of the variables that have an effect on the physicochemical properties of proteins. Therefore, it is necessary to establish the optimal conditions for each type of food. The use of ultrasound is a promising technique in food technology with a low impact on the environment, and it has thus become known as a green technology. Therefore, this review focuses on the application of high-energy ultrasound to food; its effects on the functional properties of proteins; and how different conditions such as the frequency, time, amplitude, temperature, and protein concentration affect the functional properties.     

Equation of state at the adiabat of unloading

On the assumption that condensed matter at high pressures and temperatures behaves as an ideal gas, a functional dependence of the adiabatic exponent on the Grüneisen constant was obtained, as well as an equation of state that relates the velocity of the shock front and the mass velocity in the shock wave. The calculated estimates of the rate of unloading for cadmium, tin, aluminum, and iron are given as functions of the mass velocities. A comparison with experimental data shows that such an equation of state sufficiently well describes the behavior of the substance and can be used instead of the conventional semiempirical dependences.     

The effect of masker interaural phase on the detection of a monaural signal

The masking-level difference (MLD) for a 500-Hz monaural pure-tone signal was examined as a function of the interaural phase shift of a 100-Hz-wide noise band centered on 500 Hz. Results indicated that the MLD decreased in magnitude as the interaural phase shift of the masker increased. In a second experiment, the 100-Hz-wide noise band was used as both the masker and the signal in order to examine the detection cues of interaural time difference and interaural level difference separately. Again, the interaural phase of the masker was varied, and an Sm signal was presented. Results indicated that the MLD decreased as a function of increasing masker interaural temporal difference for the time cue, but that the MLD did not change systematically for the level cue. The deterioration of binaural detection as a function of increasing masker interaural phase difference was not as great as that which has been reported in localization and lateralization experiments.