ABSTRACT
2,6-Di-tert-butyl-hydroxytotulene (BHT) is a widely used antioxidant in various fields. In this study, we explored comprehensively the mechanisms and kinetics of BHT degradation to produce isobutene using the density functional theory method. Furthermore, the intrinsic chemical reactivity of BHT was investigated using the electrostatic potential, average local ionization energy, and Fukui function, and the most likely reaction site with OH radical was predicted. Two initiation pathways of BHT with OH radicals were reported. The OH addition pathways at the C2 site of BHT was found more likely to occur than the pathways of H abstracts from the t-butyl group due to the lower energy barrier. Rate constants of two initiation pathways were calculated by transition state theory, and they were promoted by the temperature rise. Mayer bond order and localized molecular orbitals analysis were conducted to reveal the variation of the chemical bonds in the reaction process. The tertiary butyl radical that had been generated in the OH-addition reaction was more likely to generate isobutene with the participation of oxygen. Overall, this research could help to reveal the transformation mechanism of isobutene produced by BHT degradation.
ABSTRACT
Thermal stability is the key issue in the industrial application of supported metal nanocatalysts. A combination method of density functional theory calculations, machine learning, and molecular dynamics simulation is adopted to study the sintering behavior of supported platinum (Pt) nanoparticles on graphene or TiO2 nanosheet, and analyze sintering mechanisms under different temperatures, particle sizes, and metal support interactions (MSIs). The results show that the agglomeration of supported nanoparticles is mainly based on the mechanism of small particle migration and growth. Small-sized particles with high surface energy determine the sintering rate. In addition, the increase of temperature is conducive to the agglomeration of particles, especially for systems with strong MSI. Based on the analysis of the sintering process, a sintering kinetic model of supported Pt nanoparticles related to particle size, temperature, and MSI is established, which provides theoretical guidance for the design of supported metal catalysts with high thermal stability.
ABSTRACT
The authors and journal apologize for errors in the above paper, which appeared in volume 26 part 3, pages 303319. The errors relate to the legend of Fig. 1A on page 307 and the artwork of Fig. 8D on page 316:
ABSTRACT
PURPOSE: Extracorporeal shock wave therapy (ESWT) has been reported as a new therapy for carpal tunnel syndrome (CTS). However, few studies have compared ESWT with the local corticosteroid injection (LCI). METHODS: In this study, a randomized controlled trial comparing 30 patients with ESWT and 25 patients treated with LCI was conducted. The clinical outcomes were obtained with tests including the visual analog scale (VAS) for pain and paresthesia, the Boston Carpal Tunnel Questionnaire (BQ), and a nerve conduction study, before the study started and at three, nine, and 12 weeks after the start of the treatment. RESULTS: Significantly greater improvement in the VAS and BQ scores was noted for the ESWT group than for the LCI group (P < 0.05). For the nerve conduction study, there was a significant improvement in the median nerve sensory nerve action potential distal latency at the nine and 12-week follow-ups for the ESWT group. CONCLUSIONS: ESWT is a useful noninvasive short-term treatment for mild to moderate carpal tunnel syndrome and elicits a better recovery than LCI does, but more research is needed to test the clinical outcomes of ESWT.
