A high‐order Godunov method for one‐dimensional convection‐diffusion‐reaction problems

In this article we develop a high‐order Godunov method for one‐dimensional convection‐diffusion‐reaction problems where convection dominates diffusion. The heart of this method comes from incorporating the diffusion term via the slope of the linear representation (recovery) of the solution on each grid cell. The method is conservative and explicit. Therefore, it is efficient in computing time. For constant coefficient linear convection, diffusion, and Lipschitz‐type reaction, the properties of the total variation stability and monotonicity preservation are proved. An error estimation is derived. Computational examples are presented and compared with the exact solutions. © 2000 John Wiley & Sons, Inc. Numer Methods Partial Differential Eq 16: 495–512, 2000     

Effects of phenolic resin on the electrochemical performance of Li3V2(PO4)3/C cathode materials

As a kind of lithium-ion battery cathode material, monoclinic lithium vanadium phosphate/carbon Li₃V₂(PO₄)₃/C was synthesized by adopting phenolic resin as carbon source, both for reducing agent and coating material. The crystal structure and morphology of the samples were characterized through X-ray diffraction (XRD) and scanning electron microscope (SEM). Galvanostatic charge-discharging experiments and electrochemical impedance spectrum (EIS) were utilized to determine the electrochemical insertion properties of the samples. XRD data revealed that phenolic resin does not change the crystal structure of Li₃V₂(PO₄)₃/C. Furthermore, the morphology of grains and the electronic conductivity of Li₃V₂(PO₄)₃/C were improved. Galvanostatic charge-discharging and EIS results showed that the optimal electrochemical properties and the minimum charge-transfer resistance of Li₃V₂(PO₄)₃/C can be reached when added by 5 wt.% of redundant carbon (except the carbon needed to reduce V⁵⁺ to V³⁺). The initial discharge capacity is 128.4 mAh g^?1 at 0.2 C rate and 101.2 mAh g^?1 at 5 C in the voltage range of 3.0～4.3 V.     

药物的手性拆分

手性药物在医学应用中具有广阔的应用前景。本文介绍了常用药物的手性拆分方法,包括机械拆分法、经典成盐拆分法、色谱拆分方法及酶拆分法等的拆分原理,并对它们的应用领域及优缺点进行了比较分析。以期对新药的手性拆分及现有药物的拆分优化提供一般的理论参考。     

融合信息技术,探索军队院校力学课程的形成性考核模式

融合信息技术,探索以学生为中心、以能力培养为导向的力学课程形成性考核模式,并以流体力学课程实施为例,把学生的学习过程细分为教学前、中、后三阶段,对其知识学习情况、自主学习能力、随堂学习能力、团队合作能力、交流研讨能力、求解问题能力及应用创新能力等进行全面监督、测评与激励,促进学生全方位发展,通过两种考核模式比较综合地给...     

Ternary phase diagrams and metastable zone width of azithromycin in water–acetone solvent mixtures

Journal of Thermal Analysis and Calorimetry - The transition water activity of azithromycin in water–acetone solvent mixtures at temperatures 293.15 K, 298.15 K,...     

高温离子热快速合成AlPO4-42分子筛

本文采用离子热合成法,以磷酸为磷源、异丙醇铝为铝源,在溴化1-丁基-3-甲基咪唑鎓([BMIM]Br)离子液体中于280℃快速合成了AlPO_4-42分子筛,并用该方法快速合成了其他类型的磷酸铝分子筛。通过X射线衍射、扫描电镜、比表面积孔隙率分析、固体核磁等表征手段研究了不同物料配比、模板剂、晶化时间对合成AlPO_4-42分子筛的影响以及AlPO_4-42分子筛的比表面积、孔容大小和孔道中的填充物。结果发现,在4min时已经形成了AlPO_4-42分子筛的结构。合成出的AlPO_4-42分子筛具有十四面体的形貌,这与采用常规方法得到的AlPO_4-42分子筛晶体的立方体形貌明显不同,而且AlPO_4-42分子筛的比表面积和孔容都有所改变。在合成AlPO_4-42分子筛的过程中离子液体和模板剂协同导向产物的形成。     

外腔式宽调谐被动调QNd:YVO_4/PPMgLN光学参量振荡器

报道了一个低阈值宽调谐、被动调Q、单谐振掺MgO的周期性极化铌酸锂晶体(PPMgLN)光学参量振荡器。利用被动调Q的Nd:YVO4激光器作为泵浦源,采用外腔结构,在室温下,实现了PPMgLN晶体的准相位匹配光学参量振荡。光参量振荡的阈值仅为0.27W(单脉冲能量4.5μJ、脉宽35ns);在泵浦光为1.35W(脉冲能量8.2μJ、脉宽35ns),PPMgLN周期为31μm时,获得了161.9mW,3.202μm脉冲激光输出;同时获得了98.5mW的1.594μm信号光输出,总的光光转化效率达到19.3%。通过改变晶体的周期,实现了闲频光3.13～4.19μm,信号光1.43～1.65μm的宽带可调谐激光输出。