The Microwave-Assisted Green Synthesis of TiC Powders

Titanium carbide (TiC) is an important engineering material and has found widespread applications. Currently, TiC is typically synthesized through carbothermal reduction, requiring a high temperature (ca. 1700–2300 °C) and long reaction time (ca. 10–20 h), which is not eco-friendly. During a conventional reaction path, anatase TiO2 (A-TiO2) was first converted to rutile TiO2 (R-TiO2), which was subsequently reduced to TiC. Herein, we explored the synthesis of TiC powders with the assistance of microwave heating. In particular, we achieved the conversion of A-TiO2, which was more reactive than R-TiO2 for the carbothermal reduction, to TiC, which was directly due to quick microwave heating. As such, the carbothermal reduction started at a much lower temperature of ca. 1200 °C and finished within 30 min when reacting at 1400 °C, leading to significant energy saving. This study shows that microwave-assisted synthesis can be an effective and green process for preparing TiC powders, which is promising for future large-scale production. The influence of the reaction temperature, the reaction duration, and the carbon content on the synthesis of TiC powders was investigated

Emotional learning retroactively promotes memory integration through rapid neural reactivation and reorganization

Neutral events preceding emotional experiences can be better remembered, likely by assigning them as significant to guide possible use in future. Yet, the neurobiological mechanisms of how emotional learning enhances memory for past mundane events remain unclear. By two behavioral studies and one functional magnetic resonance imaging study with an adapted sensory preconditioning paradigm, we show rapid neural reactivation and connectivity changes underlying emotion-charged retroactive memory enhancement. Behaviorally, emotional learning retroactively enhanced initial memory for neutral associations across the three studies. Neurally, emotional learning potentiated trial-specific reactivation of overlapping neural traces in the hippocampus and stimulus-relevant neocortex. It further induced rapid hippocampal-neocortical functional reorganization supporting such retroactive memory benefit, as characterized by enhanced hippocampal-neocortical coupling modulated by the amygdala during emotional learning, and a shift of hippocampal connectivity from stimulus-relevant neocortex to distributed transmodal prefrontal-parietal areas at post-learning rests. Together, emotional learning retroactively promotes memory integration for past neutral events through stimulating trial-specific reactivation of overlapping representations and reorganization of associated memories into an integrated network to foster its priority for future use

Investigation on the preparation and properties of monodispersed Al2O3-ZrO2 nanopowder via Co-precipitation method

With Al2O3 as inhibitor (which can be etched after calcination), monodispersed Al2O3-ZrO2 nanopowder was successful prepared by co-precipitation method. The as-prepared powders were characterized by acoustic particle sizer (APS), SEM, TEM and XRD, respectively. Crystalline and non-agglomerated nanometric Al2O3-ZrO2 powders with very small crystallite size (similar to 7 nm) and narrow size distribution can be obtained. The relative yield was effected dramatically by pH and the ratio of M-AHC: M-Zr. Green bodies have an ultrafine uniform microstructure without apparent macropore through 200 MPa CIP treatment. The relative density of the grains can be reached to similar to 98.2% by sintering at 1050 degrees C for 4 h, with an average grain size degrees 39 nm. (C) 2016 Elsevier B.V. All rights reserved