Path integral quantization corresponding to the deformed Heisenberg algebra

In this paper, the deformation of the Heisenberg algebra, consistent with both the generalized uncertainty principle and doubly special relativity, has been analyzed. It has been observed that, though this algebra can give rise to fractional derivative terms in the corresponding quantum mechanical Hamiltonian, a formal meaning can be given to them by using the theory of harmonic extensions of function. Depending on this argument, the expression of the propagator of the path integral corresponding to the deformed Heisenberg algebra, has been obtained. In particular, the consistent expression of the one dimensional free particle propagator has been evaluated explicitly. With this propagator in hand, it has been shown that, even in free particle case, normal generalized uncertainty principle and doubly special relativity show very much different result.     

Path to achieving molecular dispersion in a dense reactive mixture

A uniform dispersion of reactants is necessary to achieve a complete reaction involving multicomponents. In this study, we have examined the role of plasticizer in the reaction of two seemingly unlikely reactants: a highly crystalline hexamethylenetetramine (HMTA) and a strongly hydrogen bonded phenol formaldehyde resin. By combining information from NMR, infrared spectroscopy and differential scanning calorimetry, we were able to determine the role of specific intermolecular interactions necessary for the plasticizer to dissolve the highly crystalline HMTA and to plasticize the phenol formaldehyde resin in this crosslinking reaction. The presence of the plasticizer increased the segmental mobility, disrupted the hydrogen bonded matrix, and freed the hydroxyl units, which further increased the solubility of the HMTA. Both the endothermic and exothermic transitions are accounted for in the calorimetric data obtained. For the first time, it is possible to obtain the effective molar ratio of each component needed to complete the crosslinking reaction efficiently. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1519–1526     

甲烷浓度对碳化硅基底金刚石薄膜摩擦性能影响

利用热丝化学气相沉积法(HFCVD)在碳化硅基底上制备金刚石薄膜,采用场发射扫描电子显微镜、拉曼光谱仪、原子力显微镜研究了在不同甲烷浓度条件下制备的金刚石薄膜表面形貌及物相组成,在干摩擦条件下通过往复式摩擦磨损实验测试并计算了已制备金刚石薄膜的摩擦系数和磨损率,结合物相分析及摩擦磨损实验结果分析了甲烷浓度的改变对金刚石薄膜摩擦磨损性能的影响。结果表明,由于甲烷气体含量的升高,金刚石薄膜结晶质量下降,薄膜由微米晶向纳米晶转变。摩擦磨损实验结果显示:3%甲烷浓度条件下制备的金刚石薄膜耐磨性较好,磨损率为2.2×10^-7 mm³/mN;5%甲烷浓度条件下制备的金刚石薄膜摩擦系数最低(0.032),磨损率为5.7×10^-7 mm³/mN,制备的金刚石薄膜的耐磨损性能相比于碳化硅基底(磨损率为9.89×10^-5 mm³/mN)提升了两个数量级,显著提高了碳化硅基底的耐磨性。     

气体压强对纳秒激光诱导空气等离子体特性的影响

环境气体的压强对激光诱导等离子体特性有重要影响.基于发射光谱法开展了气体压强对纳秒激光诱导空气等离子体特性影响的研究,探讨了气体压强对空气等离子体发射光谱强度、电子温度和电子密度的影响.实验结果表明,在10-100 kPa空气压强条件下,空气等离子体发射光谱中的线状光谱和连续光谱依赖于气体压强变化,且原子谱线和离子谱线强度随气体压强的变化有明显差别.随着空气压强增大,激光击穿作用区域的空气密度增加,造成激光诱导击穿空气几率升高,从而等离子体辐射光谱强度增大.空气等离子体膨胀区域空气的约束作用,增加了等离子体内粒子间的碰撞几率以及能量交换几率,并且使离子-电子-原子的三体复合几率增加,因此造成原子谱线OⅠ777.2 nm与NⅠ821.6 nm谱线强度随着气体压强增大而增大,在80 kPa时谱线强度最高,随后谱线强度缓慢降低.而离子谱线N Ⅱ 500.5 nm谱线强度在40 kPa时达到最大值,气体压强大于40 kPa后,谱线强度随压强增加而逐渐降低.空气等离子体电子密度均随压强升高而增大,在80 kPa后增长速度变缓.等离子体电子温度在30 kPa时达到最大值,气体压强大于30 kPa后,等离子体电子温度逐渐降低.研究结果可为不同海拔高度的激光诱导空气等离子体特性的研究提供重要实验基础,为今后激光大气传输、大气组成分析提供重要的技术支持.     

基于横向莫尔条纹的自准直测角方法

本文提出了基于横向莫尔条纹的自准直测角方法,用遮光原理分析了莫尔条纹的位移放大作用.并基于该方法搭建了原理光路,得到的莫尔条纹信号稳定且能够满足测量需求.在此基础上对系统进行了定量标定,简化了数据处理步骤,实现了动态测量,系统分辨率达到10″,进一步明确将该方法应用到自准直仪中可以有效提高仪器分辨率.     

Recent Progress in the $L_p$ Theory for Elliptic and Parabolic Equations with Discontinuous Coefficients

In this paper, we review some results over the last 10-15 years on elliptic and parabolic equations with discontinuous coefficients. We begin with an approach given by N. V. Krylov to parabolic equations in the whole space with $\rm{VMO}_x$ coefficients. We then discuss some subsequent development including elliptic and parabolic equations with coefficients which are allowed to be merely measurable in one or two space directions, weighted $L_p$estimates with Muckenhoupt ($A_p$) weights, non-local elliptic and parabolic equations, as well as fully nonlinear elliptic and parabolic equations.     

基于化学学科认知障碍突破的中考复习教学实践* ——以“二氧化碳的性质”为例

分析学生对二氧化碳的3个典型学科认知障碍,以“二氧化碳的捕捉”为情境,通过“尝试捕捉二氧化碳”“谁在捕捉二氧化碳”“捕捉背后的原理”等3个主要环节,实现对学科认知障碍的突破,展示了一种新的中考复习教学思路。     

Cycloparaphenylene (CPP) series are molecular models for graphene armchair edges: trends in their aromaticity and cyclic conjugation are evaluated

Cycloparaphenylene ([r]CPP) and cyclacene ([r]CA) series are models for short carbon nanotubes. It is shown that armchair edges in model cycloparaphenylenes possess greater aromaticity and cyclic conjugation than do zigzag edges in model cyclacenes. According to Aihara’s bond resonance energy (BRE) and Bosanac and Gutman energy effect (ef) measurements, cycloparaphenylenes are twice as aromatic as cyclacenes. The general solution of all eigenvalues of all members of the cycloparaphenylene series is given. The origin of the recurrence of some eigenvalues are determined.     

Approximate Entropy of Brain Network in the Study of Hemispheric Differences

Human brain, a dynamic complex system, can be studied with different approaches, including linear and nonlinear ones. One of the nonlinear approaches widely used in electroencephalographic (EEG) analyses is the entropy, the measurement of disorder in a system. The present study investigates brain networks applying approximate entropy (ApEn) measure for assessing the hemispheric EEG differences; reproducibility and stability of ApEn data across separate recording sessions were evaluated. Twenty healthy adult volunteers were submitted to eyes-closed resting EEG recordings, for 80 recordings. Significant differences in the occipital region, with higher values of entropy in the left hemisphere than in the right one, show that the hemispheres become active with different intensities according to the performed function. Besides, the present methodology proved to be reproducible and stable, when carried out on relatively brief EEG epochs but also at a 1-week distance in a group of 36 subjects. Nonlinear approaches represent an interesting probe to study the dynamics of brain networks. ApEn technique might provide more insight into the pathophysiological processes underlying age-related brain disconnection as well as for monitoring the impact of pharmacological and rehabilitation treatments.