Regulating Surface and Grain‐Boundary Structures of Ni‐Rich Layered Cathodes for Ultrahigh Cycle Stability

The wide applications of Ni‐rich LiNi_1‐x‐yCo_xMn_yO₂ cathodes are severely limited by capacity fading and voltage fading during the cycling process resulting from the pulverization of particles, interfacial side reactions, and phase transformation. The canonical surface modification approach can improve the stability to a certain extent; however, it fails to resolve the key bottlenecks. The preparation of Li(Ni_0.4Co_0.2Mn_0.4)_1‐xTi_xO₂ on the surface of LiNi_0.8Co_0.1Mn_0.1O₂ particles with a coprecipitation method is reported. After sintering, Ti diffuses into the interior and mainly distributes along surface and grain boundaries. A strong surface and grain boundary strengthening are simultaneously achieved. The pristine particles are fully pulverized into first particles due to mechanical instability and high strains, which results in serious capacity fading. In contrast, the strong surface and the grain boundary strengthening can maintain the structural integrity, and therefore significantly improve the cycle stability. A general and simple strategy for the design of high‐performance Ni‐rich LiNi_1‐x‐yCo_xMn_yO₂ cathode is provided and is applicable to surface modification and grain‐boundary regulation of other advanced cathodes for batteries.     

Precursor system of liquid crystalline phase containing propolis microparticles for the treatment of periodontal disease: development and characterization

Precursor systems of liquid crystalline phase were prepared using the surfactant PPG-5-Ceteth-20, isopropyl myristate, and water; gelatin microparticles containing propolis were then added into these systems. Homogeneity of dispersion, the in-system microparticle morphology, and sedimentation behavior of each formulation were evaluated. The rheological and mechanical properties (hardness, compressibility, and adhesiveness), the work of syringing, and the propolis release profile were also evaluated. All the formulations exhibited pseudoplastic flow and thixotropy, and they displayed storage modulus, loss modulus, dynamic viscosity, and loss tangent that depended on temperature, frequency, and composition. Mechanical properties varied significantly among the formulations being affected by changes in the composition and temperature. Raising the concentration of surfactant and adding propolis microparticles significantly decreased the work of syringing. The drug release was non-Fickian (anomalous) and there was no significant difference between the tested systems in the times required for 10%, 30%, and 50% release of the initial drug loading.     

反应温度对液态聚硅烷高压合成聚碳硅烷性能的影响

以液态聚硅烷(LPS)为原料,在高压釜内反应制备了聚碳硅烷(PCS)先驱体。研究发现,随着反应温度的升高．PCS的分子量增大,产率提高,软化点提高．Si—H键含量降低．在反应过程中LPS首先转化为小分子量的PCS．然后是小分子的PCS间发生脱氢及少量脱甲烷缩合使分子量长大。450℃后,反应产率明显增加,分子量分布出现中分子量峰。     

研究液体表面特性的激光动态光散射系统

本文介绍了我们已建立的用微机控制的激光散射实验系统,并用已知常规液体及低介面张力的二相微乳体系样品测量,实验结果与预期相符。     

应用双头电导探针技术测量气液两相泡状流局部参数

本研究应用双头电导探针技术测量气泡局部参数,从而揭示了气液两相泡状流的内部流动规律。     

Observations of the Effects of Oxide Skins on the Oscillations of Electromagnetically Levitated Metal Droplets

The surface tensions of liquid metals can be derived from measurements of the natural oscillation frequencies of levitated drops through the Rayleigh relation, In general, during terrestrial measurements, a spectrum consisting of three to five dominant oscillation frequencies (in the range of 30 to 60 Hz) are found, rather than the single one predicted by Rayleigh, due to deformation of the drop shape by gravity and the supporting magnetic field. Cummings and Blackburn have derived a correction factor to align the measured frequencies with the Rayleigh frequency, which has been shown to hold through micro-gravity experiments by Egry et al., for the majority of metals that have a liquid surface. Work at the NPL on more complex, commercial alloys has found that, in some cases, oscillation frequencies may be split into more complex spectra exhibiting seven to nine oscillation frequencies. This has been attributed to formations of oxide from the metal collecting on the surface of the droplet. Observations of the frequency spectra and high speed video images of the levitated drops are discussed.     

铝合金扁锭宽面竖状皱褶缺陷的成因

介绍了铝合金扁锭出现竖状皱褶缺陷的某些规律，分析了竖状皱褶缺陷产生的原因及其防止的途径，并进行了防止竖状皱褶缺陷的现场试验.