Ba0.5Sr0.5Co0.8Fe0.2O3-δ为阴极的中温固体氧化物燃料电池

 通过在阴极与氧化钇稳定的氧化锆电解质间添加Gd0.1Ce0.9O1.95 (GDC)隔层,成功地将Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF)阴极应用在中温固体氧化物燃料电池上. 由BSCF膜的高透氧率可知,BSCF在中温范围内具有很高的氧离子电导率. 在添加GDC隔层后,电池以空气为氧化剂时显示了很高的性能,极化电阻急剧下降,表明GDC隔层的添加是必要和有效的.     

主编寄语

亲爱的读者、作者和所有关心与支持本刊的朋友们,《大学化学》2005年第 1期问世了,很高兴在此与新老朋友谈心、交心。　　盘点 2004年《大学化学》内容,我们感到欣慰。《大学化学》在传递信息、交流经验、介绍化学学科发展前沿领域的新成果和新知识、推进我国高等学校化学教育改革、提高教学质量等进行了卓有成效的工作,发挥了它作为化学教育和教学改革研究成果及信息交流平台的功能和作用。　　追溯《大学化学》近 20年来的工作,浏览它的各个栏目,评估它的辐射作用,我们更是感到它成绩斐然,工作可圈可点。尽管是双月刊,它在我国化学教…     

超音速火焰喷涂WC-Co层的高温氧化对摩擦磨损性能的影响

针对WC-12Co和WC-17Co超音速火焰喷涂层(HVOF),采用球/盘试验机研究其在大气环境下从室温至800℃的摩擦磨损性能,并结合涂层的氧化试验、氧化产物的XRD和Raman光谱分析、磨痕表面SEM观测,探索高温氧化对涂层摩擦磨损机制的影响.结果表明:WC-Co涂层在350 ～450℃时的摩擦磨损主要受Co氧化物的控制,体积流失小,为轻微氧化磨损;高于500℃时,WO3增多,虽有利于减摩却因消耗WC使涂层耐磨损性能下降;摩擦作用促进CoWQ的形成,这种钨钴双氧化物能够降低摩擦,减轻磨损,使涂层在600 ℃高温下仍维持良好的摩擦学性能;在更高温度条件下氧化剧烈,涂层性能迅速恶化而发生严重磨损,不宜作为耐磨涂层使用.Co含量较高的WC-Co涂层具有更好的高温耐磨性.     

酸碱度对金纳米结构形貌的调控及其机理研究

本文通过调节环境pH酸碱度改变聚电解质膜中氨基基团的键合状态,以控制聚电解质膜表面金纳米粒子的原位还原与自组装过程中的聚集行为,发现当聚电解质膜经pH为5.40的去离子水处理后可在其表面制备出片状金纳米结构;经pH为0.65的强酸溶液处理后,可在膜表面制备出树枝状的金纳米结构,且尺寸比pH为5.40条件下增大一倍;经pH为12.77的强碱溶液处理后,金纳米粒子的聚集状态发生改变,形成了球形纳米结构;对金纳米粒子形貌的调控机理进行了初步探讨.     

Identification of Radial Distance of Plasma Dispersionless Injection Boundary from the Injection Source

Measurements of energetic particles obtained by the two geosynchronous satellites （1991-080 and LANL-97A） are performed to investigate the plasma injection boundary and source region during the magnetospheric substorms. The measurement method is developed to allow remote sensing of the plasma injection time and the radial distance of injection boundaries by using measured energy dispersion and modelling particle drifts within the Volland-Stern electric field and the dipole magnetic field model. The radial distance of the injection boundary deduced from a dispersion event observed by the LANL-97A satellite on 14 June 1998 is 7.1RE, and the injection time agrees well with the substorm onset time identified by the Polar Ultraviolet Imager. The method has been applied to an event happened at 22.9 UT on 11 March 1998, when both the satellites （1991-080 and LANL-97A） observed the dispersionless character. The results indicate that the radial distance of injection source locates at 8.1RE at magnetotail, and particles move earthward from magnetotail into inner magnetosphere at 22.5 UT.     

物理教学中的理想化方法

在大学教学中,激发学生创造性地发现问题解决问题的能力是教学的中心任务,物理学中的理想化方法是科学方法之一．本文探讨了物理教学中怎样引入讲授理想化方法．     

逐孔起爆震动参数预报的BP神经网络模型

根据神经网络理论,结合逐孔起爆技术的特点,建立了爆破震动参数预报的BP网络模型。以某矿 山深孔台阶爆破为例,利用逐孔起爆过程中收集的原始资料和爆破震动监测数据,对建立的BP网络模型进 行了训练和应用。与实测值比较后发现,BP网络模型的预报结果更接近实测值。     

Anisotropic character of atoms in a two-dimensional Frenkel–Kontorova model

The dynamics of a certain density of interacting atoms arranged on a two-dimensional square lattice, which is made to slide over a two-dimensional periodic substrate potential with also the quare lattice symmetry, in the presence of dissipation, by an externally applied driving force, is studied. By rotating the misfit angle θ, the dynamical behaviour displays two different tribological regimes: one is smooth, the other becomes intermittent. We comment both on the nature of the atomic dynamics in the locked-to-sliding transition, and on the dynamical states displayed during the atom motion at different values of the driving force. In tribological applications, we also investigate how the main model parameters such as the stiffness strength and the magnitude of the adhesive force affect the static friction of the system. In particular, our simulation indicates that the superlubricity will appear.     

Effects of dust size distribution in ultracold quantum dusty plasmas

The effect of dust size distribution in ultracold quantum dusty plasmas are investigated in this paper. How the dispersion relation and the propagation velocity for the quantum dusty plasma vary with the system parameters and the different dust distribution are studied. It is found that as the Fermi temperature of the dust grains increases the frequency of the wave increases for large wave number dust acoustic wave. The quantum parameter of H_d also increases the frequency of the large wave number dust acoustic wave. It is also found that the frequency ω₀ and the propagation velocity v₀ of quantum dust acoustic waves all increase as the total number density increases. They are greater for unusual dusty plasmas than those of the usual dusty plasma.     

基于向量楔积的两体量子系统的纠缠度量

由于量子状态对应为一个Hilbert空间中的单位向量,因此利用向量的几何性质刻画量子状态的纠缠性是一个有趣的数学物理交叉课题.已有学者基于两个向量的楔积的模长在两体纯态系统C²■C²上定义了纠缠度量,其模长在几何上对应于平面上的一个定向平行四边形的面积.该文利用向量的楔积的模长进一步给出了两体纯态系统C³■C³和C^d■C^d上的纠缠度量,在几何上它们分别对应于一个定向平行六面体和d×(d-1)×…×4个定向平行六面体的体积.此外,提出了判定可分态的几何判据.结果表明,基于几何意义定义的纠缠度量是一种既简单又直观的度量方法.