神经网络法研究多溴代二苯胺热力学性质

通过时间分辨光谱技术详细地研究了ZnCuInS/ZnSe/ZnS量子点的激子弛豫动力学. 基于速率分布模型,波长依赖的发射动力学表明本征激子、界面缺陷态中的激子、给-受体对态中的激子都会参与量子点的发光过程,整个发光过程主要依赖于给-受体对态发射. 瞬态吸收数据表明激发后本征激子和界面缺陷物种可能会同时出现,在高激发光强下,光强依赖的俄歇复合过程也存在于量子点中     

用Matlab比较双缝干涉和双缝衍射

运用Matlab软件,对双缝衍射和双缝干涉、单缝衍射的光强分布和谱线特征进行了数值模拟,绘出实验中难以观察到的光强分布图,比较出双缝衍射与双缝干涉及单缝衍射的联系与区别。     

Spontaneous Ga incorporation in ZnO nanowires epitaxially grown on GaN substrate

Surface‐diffusion‐induced spontaneous Ga incorporation process is demonstrated in ZnO nanowires grown on GaN substrate. Crucially, contrasting distributions of Ga atoms in axial and radial directions are experimentally observed. Ga atoms uniformly distribute along the ～10 μm long ZnO nanowire and show a rapidly gradient distribution in the radial direction, which is attributed substantially to the difference between surface and volume diffusion. The understanding on the incorporation process can potentially modulate doping and properties in semiconductor nanomaterials.

     

定轴转动中打击中心位置分析

刚体定轴转动的打击中心是一个很重要的力学概念,但在很多《大学物理》教材中都没有介绍.本文以一根质量均匀分布的细杆绕端点作定轴转动为例,首先从动力学的角度,分析刚体的受力和力矩,根据动力学方程,分别计算出打击中心位置;然后从运动学角度出发,以转轴O点的切向速度和切向加速度等于零为条件,再分别寻找打击中心的位置.计算结果表明:上述4种方法得出的刚体打击中心位置是相同的.最后简介刚体打击中心在体育运动、日常生活中一些应用.     

弹簧参与的微小振动一定是简谐运动吗

振动和波动是生活中的一种非常普遍而重要的运动形式,其中简谐振动是最简单、最基本的运动,弹簧振子是研究简谐运动的最基本模型.在研究弹簧参与的微小振动时,部分学生不能很好的判定弹簧参与的微小振动是否为简谐运动.本文讨论了系统作简谐运动的充要条件,并通过4个具体例子详细分析了弹簧参与的微小振动.     

Electronic structure and optical properties of boron-sulfur symmetric codoping in 4 × 4 graphene systems

The electronic structure and optical properties of boron-doped, sulfur-doped, andboron-sulfur-codoped graphene systems have been studied by using first-principlescalculations. Energy band structure and density of states are presented to describe theelectronic properties. The doping can open the band gap and change the optical propertiesof graphene. For all optical properties of doped graphene systems, parallel(E _∥) polarization and perpendicular(E _⊥) polarization are presented. Theoptical properties under two kinds of polarizations are reflected in the range of peakheight and the change of some extraordinary features.     

Preparation and Characterization of Vanillin Cross-Linked Chitosan Microspheres of Pterostilbene

A vanillin cross-linked chitosan microsphere delivery system was established for stabilization and controlled release of pterostilbene. The prepared microspheres were characterized by SEM images, FT-IR spectra, thermogravimetry, and X-ray diffraction. FT-IR spectra results indicated that chitosan was cross-linked by vanillin successfully. Thermal analysis showed that pterostilbene had been totally incorporated into the microspheres and the encapsulation of pterostilbene decreases the rate of degradation and increases the stability. XRD analysis was conducted to confirm the results of DSC analysis. The release rate of pterostilbene from microspheres in pH 3.6 buffer solution could be up to 58.1 % within 48 h.     

A Novel Heterometallic Cluster-Based Coordinational Polymer with 2-[Bis-(2-hydroxy-ethyl)-Amino]-Ethanesulfonic Acid: Synthesis and Crystal Structure

A rare heterometallic cluster-based polymer [Cu₄(Hbhea)₄(μ ₂-OCH₃) K(CH₃OH))] _n ·(H₂O) _n (1) (H₃bhea = 2-[bis-(2-hydroxy-ethyl)-amino]-ethanesulfonic acid), has been synthesized and structurally determined by single crystal X-ray diffraction, elemental analysis. Crystallographic unit of 1 consists of four Cu(II), four Hbhea ligands, one methanol molecule, one methanol anion, one K ion and one crystal lattice water and formed anion cluster [Cu₄(Hbhea)₄(CH₃O)]^? which further constructed a 3-D polymer by linking the six-coordination K ions.     

Synthesis,Crystal Structure and Magnetic Property of a New Binuclear Copper (II) Complex Containing Water Clusters

A new binuclear copper (II) complex {[Cu₂(phen)₂(tar)(H₂O)]·8H₂O}_n (1) has been synthesized and structurally characterized by single-crystal X-ray diffraction analysis. The complex crystallizes in monoclinic system, space group P2(1), with a = 7.1710(5), b = 22.0124(15), c = 10.6691(7) Å, β = 102.541(1)°, V = 1643.95(19) Å³, Z = 2. Compound 1 is further extended to a 2D supramolecular framework by hydrogen bonds and π–π stacking interactions. Especially, six of the eight uncoordinated water molecules are connected via hydrogen bonding interactions forming 1D chain, which play an important role in the stabilization of the crystal structure. Furthermore, magnetic susceptibility measurements of this complex shows weak antiferromagnetic exchange between the copper (II) ions (J = ?5.92 cm^?1).