Direct measurement of the surface dynamics of supercooled liquid-glycerol by optical scanning a film

The surface dynamics of supercooled liquid-glycerol is studied by scanning the thickness of the glycerol film with single photon detection. Measurements are performed at room temperature well above the glycerol's glass transition temperature. It is shown that the surface dynamics of the glycerol film is very sensitive to the temperature. The linear relationship between the thickness of the film and the viscosity predicted by the Vogel--Fulcher--Tammann--Hesse (VFTH) law is also presented experimentally.     

加强习题变式教学 提高学生思维品质

习题变式教学通过启迪、引导学生自觉地运用物理的基础知识和基本规律,拓展学生的"学习空间"和"变异维数",从而实现培养和提高学生的思维品质.     

Spectral Characterization of Couplings in a Mixed Optomechanical Model *

Abstract:We study the spectrum of single-photon emission and scattering in a mixed optomechanical model which consists of both linear and quadratic optomechanical interactions. The spectra are calculated based on the exact long-time solutions of the single-photon emission and scattering processes in this system. We find that there exist some phonon sideband peaks in the spectra and there are some sub peaks around the phonon sideband peaks under proper parameter conditions. The correspondence between the spectral features and the optomechanical interactions is confirmed, and the optomechanical coupling strengths can be inferred by analyzing the resonance peaks and dips in the spectra.     

Multifunctional Small Molecule Fluorophore for Long‐Duration Tumor‐Targeted Monitoring and Dual Modal Phototherapy

In this work, a specific tumor‐targeted small molecular fluorophore for synchronous long‐duration cancer imaging, photodynamic therapy, and photothermal therapy is synthesized. This novel fluorophore exhibits specific targeting ability in certain tumors (U87MG, MDA‐MB‐231, A549, etc.) based on its inherent structure and efficiently generates local hyperthermia and reactive oxygen species simultaneously for imaging‐guided precise cancer therapy combining the photothermic and photodynamic effects under laser irradiation. Meanwhile, compared to traditional near infrared fluorophore, this novel fluorophore with significantly enhanced stability against photobleaching can prolong the time of tumor imaging and improve the phototherapy efficiency. This work presents a potential strategy to develop small‐molecule‐based cancer theranostic agents for simultaneous cancer targeting, imaging, and therapy.     

Dc-bias-field-induced dielectric relaxation and ac conduction in CaCu3Ti4O12 ceramics

The dielectric relaxation and ac conduction of CaCu₃Ti₄O₁₂ (CCTO) ceramics were investigated at different temperatures under a dc bias. The dc bias gives rise to space charge accumulation, i.e. an electrode response, resulting in the significant increase of dielectric permittivity and dielectric loss tangent. Two Debye-like relaxations, arising from electrode and grain boundary responses, are present at low frequency with an increase of the dc bias. The electrode and grain boundary relaxations are distinguished according to the impedance spectroscopy and the frequency-dependent ac conductivity. The relaxation times of electrode and grain boundary relaxation are 0.955 ms and 0.026 ms, respectively, with a dc bias of 10 V at 328 K.     

小波聚类方法和近红外光谱技术用于药片种类判别

对310个药片样品的近红外光谱数据进行了聚类分析。首先使用小波变换对光谱数据矩阵进行多尺度分解,在进行有效压缩之后,采用经典分类方法对合适选取的小波系数组合进行聚类分析,提出了小波聚类方法。该方法分别用于实验室药片、中试药片和规模生产药片样品的分析,按药片样品的组成得到4个类别。结果表明,对实验室药片和中试药片样品分类的精确度均达到100%;对于规模生产药片的分类,共120个样品中只有1个样品被错误划分,精确度也高达99.2%。近红外光谱技术结合小波聚类方法的聚类性能是令人满意的,相比经典聚类分析,更加快速、易于使用,对制药行业药片质量以及成本控制均有积极作用。     

The Essence of Operators’ Weyl Ordering Scheme and New Operator Identities for Converting Q−P Ordering to Weyl Ordering

We find new operator formulas for converting Q?P and P?Q ordering to Weyl ordering, where Q and P are the coordinate and momentum operator. In this way we reveal the essence of operators’ Weyl ordering scheme, e.g., Weyl ordered operator polynomial ${_{:}^{:}}\;Q^{m}P^{n}\;{_{:}^{:}}$ , $$\begin{aligned} {_{:}^{:}}\;Q^{m}P^{n}\;{_{:}^{:}} =&\sum_{l=0}^{\min (m,n)} \biggl( \frac{-i\hbar }{2} \biggr) ^{l}l!\binom{m}{l}\binom{n}{l}Q^{m-l}P^{n-l} \\ =& \biggl( \frac{\hbar }{2} \biggr) ^{ ( m+n ) /2}i^{n}H_{m,n} \biggl( \frac{\sqrt{2}Q}{\sqrt{\hbar }},\frac{-i\sqrt{2}P}{\sqrt{\hbar }} \biggr) \bigg|_{Q_{\mathrm{before}}P} \end{aligned}$$ where ${}_{:}^{:}$ ${}_{:}^{:}$ denotes the Weyl ordering symbol, and H _m,n is the two-variable Hermite polynomial. This helps us to know the Weyl ordering more intuitively.     

Study of a millimeter-wave squint indirect holographic algorithm suitable for imaging with large field-of-view

In this paper a millimeter-wave （MMW） squint indirect holographic method is presented, which is suitable for imaging with a large field-of-view. The proposed system employs the squint operation mode to remove the background and twin- image interferences, which achieves a similar effect to off-axis holography but leaves out the large-aperture quasi-optical component. The translational scanning manner enables a large field of view and ensures the image uniformity, which is difficult to realize in off-axis holography. In addition, a corresponding imaging algorithm for the presented scheme is developed to reconstruct the image from the recorded hologram. Some imaging results on typical objects, obtained with electromagnetic simulation, demonstrate good performance of the imaging scheme and validate the effectiveness of the image reconstruction algorithm.     

苹果盛果期冠层高光谱与其组分特征的定量模型研究

从分析苹果树盛果期冠层高光谱入手,结合同一时间的数码照片,在Erdas,ViewSpec Pro,DPS和LIBSVM等软件的支持下,采用相关分析、线性回归、逐步回归、基于BP人工神经网络分析、支持向量机回归方法,探析高光谱反射率及其转换数据与冠层组分指数间的关系。结果表明,冠层反射率受地表反光膜的影响显著;原始反射率与果叶比的相关性最好,611~680 nm为反映两者关系的特征波段;在特征波段内,依据原始反射率和果叶比所建立的4种模型都可满足预测需要,但基于BP人工神经网络模型和支持向量机回归模型整体上优于一元线性回归模型和多元线性回归模型,尤以支持向量机回归模型精度最高。研究结果可为后续的苹果遥感估产工作提供理论支持。