铬掺杂的锂离子电池正极材料LiVPO4F的制备以及电化学行为的研究

采用高温固相法2步合成了掺Cr的锂离子电池正极材料LiV_1-xCr_xPO₄F(x=0，0.01，0.03，0.05，0.07)，XRD测试表明LiV_1-xCr_xPO₄F属三斜晶系。通过恒电流充放电，循环伏安和交流阻抗实验表明：掺Cr后LiVPO₄F正极材料更有利于锂离子的嵌入和嵌出，材料的放电容量和循环性能进一步提高，例如，铬掺杂的LiVPO₄F样品在室温、0.2 C倍率下充放电，循环50周后容量在110 mAh·g^-1以上。文中还讨论了充放电容量随掺Cr量的关系，n_Cr含量为0.03的LiV_1-xCr_xPO₄F有着较高的放电平台和良好的循环稳定性。     

球型Ni(OH)2表面包覆Y(OH)3及其高温充放电性能

应用共沉淀的方法在球型Ni(OH)₂的表面包覆了一层Y(OH)₃,并研究了包覆不同含钇量后的球型Ni(OH)₂的高温充放电性能。研究结果表明:包覆Y(OH)₃的球型Ni(OH)₂具有良好的高温充放电性能。其中1C充放电条件下,包覆量为0.3%的Ni(OH)₂较好,0.2C充放电条件下,包覆量为1%的Ni(OH)₂较好。     

Direct perturbation method for perturbed complex Burgers equation

So far, Lou's direct perturbation method has been applied successfully to solve the nonlinear Schr?dinger equation(NLSE) hierarchy, such as the NLSE, the coupled NLSE, the critical NLSE, and the derivative NLSE. But to our knowledge, this method for other types of perturbed nonlinear evolution equations has still been lacking. In this paper, Lou's direct perturbation method is applied to the study of perturbed complex Burgers equation. By this method, we calculate not only the zero-order adiabatic solution, but also the first order modification.     

思维导图在仪器分析实验教学中的应用——以电化学分析实验为例

在电化学分析实验教学中引入思维导图,探讨了思维导图在仪器分析实验教学中的应用方法及效果评价。实验原理的教学依托“比较与对比图”和“逻辑思维图”,强调相关方法原理之间的联系,突出新方法的特点;实验步骤则以清晰易懂的“流程图”方式呈现。教学实践表明,思维导图有利于学生对实验基本原理的理解和掌握,提高了学生的实验兴趣,促进了学生的独立思考能力和解决问题的能力,显著提升了实验教学效果。     

Breit-Wigner formula for the scattering phase in the Stark effect

Near resonance energy, we study the asymptotic behavior of the derivative of the scattering phase as the applied electric field tends to zero. We obtain the leading asymptotics of the spectral function near a simple resonance, and as an application we rigorously prove the Breit-Wigner formula which relates the width of resonances to the time delay of particles in a homogeneous electric field.Supported by Alexander von Humboldt Stiftung     

Asymptotical solutions of coupled nonlinear Schrodinger equations with perturbations

In this paper Lou＇s direct perturbation method is applied to the perturbed coupled nonlinear Schrodinger equations to obtain their asymptotical solutions, which include not only the zero-order solutions but also the first-order modifications. Based on the asymptotical solutions, the effects of perturbations on soliton parameters and the collision between two solitons are then discussed in brief. Furthermore, we directly simulate the perturbed coupled nonlinear SchrSdinger equations by split-step Fourier method to check the validity of the direct perturbation method. It turns out that our analytical results are well supported by the numerical calculations.     

基于微课的“化工专业英语”多元化有效教学研究与实践*

遵循首要教学原理设计和实施化工专业英语课程多元化教学,采用逆向教学设计本课程教学过程,设计制作本课程微课进行翻转课堂教学,借助于超星“学习通”平台教学功能加强教学互动和教学评价,基本达成了学生学习效果好、效率高和参与度高的“3E”有效教学。     

创新综合化学实验:烷基-烷基Kumada偶联反应*

为将交叉偶联反应引入本科化学实验教学中,设计了创新综合化学实验——Kumada偶联反应。该实验选取氯化亚铜作催化剂,常温下即可反应,溶剂低毒,反应时间短,产率高,符合“绿色化学”理念。该实验在无水无氧条件下进行偶联反应,再通过萃取、分液、柱层析对产物进行分离,并引入气相色谱对产物进行定性和半定量分析。通过该实验项目的学习,学生可以掌握典型的有机化合物合成、分离手段并熟悉大型仪器设备的分析技术。     

Solitary and Periodic Waves in Coupled KdV Equations with Different Linear Dispersion Relations

Based on the invariant expansion method, some reasonable approximate solutions of coupled Korteweg-de Vries （KdV） equations with different linear dispersion relations have been obtained. These solutions contain not only bell type soliton solutions but also periodic wave solutions that expressed by Jacob/elliptic functions. The results also show that if the arbitrary constants are selected suitably, the approximate solutions may become the exact ones.