以5-(3-吡啶基)-1H-吡唑-3-羧酸为配体的钴共晶配合物的合成、晶体结构及电化学性质

采用溶剂热法合成了一种新型的钴（Ⅱ）基配合物,即{[Co（Hppc）₂][Co₂（4,4''-bipy）（H₂O）₄]（SO₄）₂·2H₂O}_n （1）,其中H₂ppc=5-（3-吡啶基）-1H-吡唑-3-羧酸,4,4''-bipy=4, 4''-联吡啶。配体H₂ppc是由吡啶环、吡唑环和羧基共同组成,同时兼具了刚性和柔性。通过单晶X射线衍射对配合物1进行了结构测定。结果显示所合成的配合物1结晶在单斜晶系C2/c空间群,包括2个晶体学独立部分：二维层状[Co（Hppc）₂]和一维链状[Co₂（4,4''-bipy）（H₂O）₄]^2-,并形成具有{4⁴·6²}{4}₂拓扑网络结构的共晶化合物。此外,配合物1呈现出良好的电化学发光（ECL）性能以及良好的超级电容器性能。     

小微企业信用风险评估的IDGSO-BP集成模型构建研究

针对传统BP神经网络在小微企业信用风险评估实际应用中,随机初始权值和阈值导致网络学习速度慢、易陷入局部解以及运算结果误差较大等缺陷,借助群智能萤火虫(GSO)算法,提出一种基于改进离散型萤火虫(IDGSO)算法的BP神经网络集成学习算法的小微企业信用风险评估IDGSO-BP模型。该模型以BP神经网络为基本框架,在学习过程中引入离散型萤火虫算法,优化设计神经网络的网络结构与连接权值,得到一组相对合适的权值与阈值,再进行新一轮网络训练,以“均平方误差最小”为评价准则,产生网络的输出结果,以此建立小微企业信用风险评估模型。其仿真实验结果表明,该模型在收敛速度及运算精度方面较传统BP神经网络模型、遗传GA-BP模型及连续GSO-BP模型有较明显优势。因此,IDGSO-BP模型可以有效提高小微企业信用风险评估的准确性。     

一类时滞捕食系统的Hopf分支

研究了一类具有修正的Leslie-Gower和Holling-IV类功能性反应函数的时滞捕食系统,讨论了该系统的局部稳定性和Hopf分支存在性, 并利用中心流形定理和规范型理论确定了Hopf分支的方向和分支周期解的稳定性.仿真实例证明了理论分析结果的正确性.     

En 中n维单形二面角的角平分面的性质

利用距离几何的理论与方法研究了En中n维单形内二面角与外二面角的角平分面的性质,获得了n维单形内二面角与外二面角平分面的2个定理.     

求解方程的迭代过程中算法停止准则的讨论

分析了在求解方程的迭代过程中,算法中常用单一停止准则的不足,并给出了一些组合的停止准则,数值实验表明,这些停止准则是有效的.     

PbSe纳米棒的模板合成及其性质

在表面活性剂十六烷基三甲基溴化铵(CTAB)存在下,利用N2 H4·H2O还原H2SeO3合成出单质硒纳米管,然后以硒纳米管为模板,与Pb(NO3):和N2 H4·H2O在常压低温下反应,制备了PKSe纳米棒.采用电子透射电镜、X射线衍射等方法对产物进行了表征.探讨了PbSe纳米棒的形成机理和制备反应的影响因素.测定了产物的荧光性质,并利用电位扫描伏安法研究了所得PbSe纳米棒的电化学性质.结果表明,所得产物在碱性介质中电化学活性较高,在循环伏安曲线上出现明显的氧化峰和还原峰.     

Er3+掺杂Ge-Ga-S-KBr硫卤玻璃的中红外发光和多声子弛豫的研究

用熔融急冷法制备了系列不同Er3+离子掺杂浓度的Ge-Ga-S-KBr硫卤玻璃,测试了样品折射率、吸收光谱、中红外荧光光谱。通过吸收光谱计算了Er3+离子吸收谱线的振子强度,应用Judd-Ofelt理论计算分析了Er3+离子在Ge-Ga-S-KBr硫卤玻璃中的强度参数Ωi ( i = 2 , 4 , 6) 、自发辐射跃迁几率A、荧光分支比?和辐射寿命?rad等光谱参数。研究了808nm激光泵浦下样品中红外荧光特性与掺杂浓度之间变化关系,并用Futchbauer-Ladenburg公式分别计算了2.8?m处的受激发射截面。结果表明,在808nm 激光泵浦下观察到了2.8?m中红外荧光,分别对应于Er3+： 4I11/2?4I13/2跃迁,当Er3+离子掺杂浓度从0.4wt%增加到1.0wt%时,中红外荧光强度都随相应增加,计算的Er3+:4I11/2?4I13/2跃迁多声子驰豫速率分别为37 s-1。     

Luminescent properties of La2LiTaO6:Mn4+ and its application as red emission LEDs phosphor

A novel phosphor, Mn⁴⁺ doped La₂LiTaO₆, was developed by solid-state reaction method. The luminescent spectra and emission efficiencies of La₂LiTaO₆:Mn _x ⁴⁺ (x = 0.001, 0.003, 0.005 and 0.01) were discussed. The effects of co-doped charge compensation ions, M = Mg²⁺, Ca²⁺, Na⁺, were investigated, respectively. The excitation spectra indicated that La₂LiTaO₆:Mn⁴⁺ could be effectively excited by both NUV light and blue light. The emission spectra of the phosphor exhibit a broadband ranging from 670 to 720 nm with the maximum at about 709 nm in deep red region. The co-doping of Mg²⁺ could significantly improve the luminescent properties of La₂LiTaO₆:Mn⁴⁺. Thus, phosphor La₂LiTaO₆:Mn⁴⁺, Mg²⁺ can serve as a key component to improve color rendering of blue-chip white-LEDs.     

证券组合投资的多目标区间数线性规划模型

本文提出了证券组合投资的多目标区间数线性规划模型，引入了收益——风险偏好参数和优化水平参数。投资者可以根据对风险的喜好程度和金融市场的客观情况，适当估计这两个参数，从而得到相应情况下的有效投资方案，使投资过程更具柔性，而且更接近于实际情况。     

A co-doping approach towards enhanced ionic conductivity in fluorite-based electrolytes

A co-dopant strategy is used to investigate the effect that the elastic strain in the lattice has on the grain ionic conductivity of doped ceria electrolytes. Based on critical dopant ionic radius (r_c), different compositions in the Lu_xNd_yCe_1−x−yO_2−δ (x + y = 0.05, 0.10, 0.15, and 0.20) system are studied. Dopants are added such that the weighted average dopant ionic radius matches r_c for all the compositions. Dense ceramic discs are prepared using conventional solid oxide route and sintering methods. Precise lattice parameter measurements are used to calculate the lattice strain. The ionic conductivity of the samples is measured in the temperature range of 250 °C to 700 °C using two-probe electrochemical impedance spectroscopy technique. The elastic strain present in Lu_xNd_yCe_1−x−yO_2−δ system is found to be negligible when compared to Lu_xCe_1−xO_2−δ (negative) and Nd_xCe_1−xO_2−δ (positive) systems. Grain ionic conductivity of Lu_xNd_yCe_1−x−yO_2−δ (where x + y = 0.05) at 500 °C is observed to be 1.9 × 10^− 3 S/cm which is twice as high as that of Lu_0.05Ce_0.95O_2−δ. These results extend the validity of the r_c concept as a strategy for co-doping ceria electrolytes and open new designing avenues for solid oxide electrolytes with enhanced ionic conductivity.