“守正”和“创新”:当代中国艺术发展的新命题

“守正创新”的“守”是强调对文化最根本最核心的东西要“守”;“正”强调的是正大光明、浩然正气,是中华民族几千年精神文明立身的根基。“守正、创新”关注的是推进文艺发展的方法论,两者互补互制而有侧重,必然成为当下我国文化发展的新命题。

层状正极材料力学劣化及改善措施

力学性质是材料的本质属性之一,随着锂离子电池应用于电动汽车、智能电网领域,活性材料的力学特性开始受到关注。动力电池、储能电池的循环寿命需要达到几千次,活性材料晶胞亦经历几千次规律的膨胀、收缩,材料颗粒的力学劣化成为必须面对的新挑战。本文以团队的研究结果为主,总结了锂电池层状正极材料力学劣化机制和改善措施。首先,讨论了正极材料的力学研究基础,明确正极材料符合弹性形变,可以使用胡克方程分析;其次,回顾了正极材料力学劣化行为符合“损伤-断裂”模型,应力产生缺陷,逐渐积累直至断裂,电解液会沿着裂缝扩散至电池内部发生副反应,造成循环跳水;最后,总结了抑制材料力学劣化的主要策略,重点介绍了降低晶胞形变和表面构筑刚性层,降低晶胞变化是通过减小材料应变降低颗粒应力,表面构筑刚性层是阻挡电解液扩散至开裂的体相,这些策略都显著提高了材料的循环寿命。总的来说,电极材料的力学劣化是无法避免的,但可以通过合适的改善措施,延迟、减缓力学劣化的影响。

做美的“布道者”:以书法美育实践为例

当前,书法艺术的推广普及最急迫最重要也最根本的挑战是“美育”。书法艺术美的大普及,需要一批书法“布道者”,承担宣讲者、解说者、传播者、鉴赏者的角色。书法的“美育认知”是一个书法家成败或成就高下的第一决定性要素。书法“美育家”应注意阶段性、目标设置、距离感、出发点等四个方面,立足于“书法”和“美”这两个基点,紧紧围绕“作品”(名作经典)展开工作,为我们这个时代的书法艺术作出新建树。

基于片区开发的城市地下公共空间一体化开发模式思考

当前超大型的城市地下公共空间界面复杂、涉及专业及管理部门多,传统的规划及设计分工和管理已经不能满足要求.结合广州南沙横沥岛尖地下公共空间综合体的开发实践,探讨了复杂地下空间规划设计的管理问题,涉及管理机制、开发模式、技术保障等多方面因素,提出基于片区开发的城市地下公共空间一体化开发模式,以期为类似片区开发的城市地下公共空间规划设计管理工作提供参考.

Critical electronic structures controlling phase transitions induced by lithium ion intercalation in molybdenum disulphide

We report on first-principles studies of lithium-intercalation-induced structural phase transitions in molybdenum disulphide (MoS2 ), a promising material for energy storage in lithium ion batteries. It is demonstrated that the inversion-symmetry-related Mo-S p-d covalence interaction and the anisotropy of d-band hybridization are the critical factors influencing the structural phase transitions upon Li ion intercalation. Li ion intercalation in 2H-MoS2 leads to two competing effects, i.e. the 2H-to-1T transition due to the weakening of Mo-S p-d interaction and the D 6h crystal field, and the charge-density-wave transition due to the Peierls instability in Li-intercalated 2H phase. The stabilization of charge density wave in Li-intercalated MoS2 originates from the enhanced electron correlation due to nearest-neighbor Mo-Mo d-d covalence interaction, conforming to the extended Hubbard model. The magnitude of charge density wave is affected by Mo-S p-d covalence interaction and the anisotropy of d-band hybridization. In 1T phase of Li-intercalated MoS2 , the strong anisotropy of d-band hybridization contributes to the strong Fermi surface nesting while the d-band nonbonding with S-p facilities effective electron injection.

Synergetic effects of blended materials for Lithium-ion batteries

LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2, LiMn_2O_4 and LiCoO_2 are paired to make the blended materials for the cathode of lithium-ion batteries. The factors impacting on the characteristics of blended materials are studied using constant current charge/discharge measurement and electrochemical impedance spectroscopy. The results show that the three pairs of blended materials exhibit very different synergetic effects in high C-rate discharging. The mechanism of particle synergetic effect has a physical root on the compensating material property of blending components, which fundamentally correlates with their similarity and difference in crystalline and electronic structures. The AC impedance show the obvious changes that alternate the high C-rate performance, due to reduced particle impedance in blended materials. The pairs of LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2-LiMn_2O and LiCoO_2-LiMn_2O_4 present obvious increases in high C-rate reversible capacities than does the pair LiCoO_2-LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2.

Experimental Measurement of Valence Electron Concentration of Icosahedral AlPdMn Quasicrystal

The valence charge density distribution for the icosahedral AlPdMn （i-AlPdMn） quasicrystal was obtained with the structure factors of the nine strongest symmetry inequivalent reflections, which were refined by using the quantitative convergent beam electron diffraction （QCBED） technique. It shows that the bonding charge is localized. The enhanced charge density in the middle of the aluminum-transition-metal （Al-TM） bond shown in the valence charge density＇ distribution is the characteristic of covalent bonding. Assuming that the shape of an atom is a sphere with covalent radius, the number of electrons that each atom gains or loses in 55 different pseudo-Mackay clusters （PMCs） was cal- culated based on the obtained valence charge density distribution. It indicates that almost all the atoms lose electrons except a few Pd atoms that are in some particular shells. It also shows that the atoms of an identified element could have different valences because of chemically and/or structurally different local environments in which the atoms situ- ate. Regardless of the topology and chemical occupancy, the number of valence electrons per atom in a cluster is close to 1.69. This strongly suggests that the pseudo-Mackay clusters are stabilized at a certain elec- tron concentration.

水墨宗师说董源

中国山水画从古代丹铅青黄开始,一直是色彩的天下。老子曰"五色令人目盲",子夏曰"素以为绚兮",先人的告诫,当然是十分重要的,但反过来恰恰证明,"五色""绚"本是绘画正道,是当行本色。只不过一上升到哲学思维的高度,却反过来居高临下地指责"目盲""素",为追求改变思考立场以示深奥,而视"五色""绚"为世俗。在我们看来,这多少有点故弄玄虚、大言炎炎的意思,至少,画家们是不以为然的。

《瑞鹤图》：中国绘画史上的特例

北宋文艺皇帝宋徽宗,是一个书画兼长的大家,又精通金石博古之学、园艺庭院之学、鉴定收藏之学、编纂著录之学。抛开他作为皇帝的特殊身份和北宋末期国破家亡的失败,仅论他对于中国艺术史的贡献,是怎么评价都不为过的。他最经典的传世作品便是《瑞鹤图》。