In order to clarify the effect of sodium on the heterogeneous adsorption of NO on a char surface, several reasonably simplified saturated and unsaturated char models were selected as research objects, and Na atoms were decorated on the char models. Each char model and NO adsorption product were optimized by using density functional theory at the GGA-PBE (generalized gradient approximation-Perdew−Burke−Ernzerhof) level to obtain the adsorption energy of NO on different models. The results indicate that the addition of Na atoms catalyzes the adsorption of NO molecules by an saturated char structure, the adsorption form is changed from physisorption to chemisorption, and the adsorption energy is increased from −15.6 to −98.2 kJ/ mol. The adsorption energy of NO molecules with an unsaturated armchair-type char structure containing edge active sites is affected by sodium atoms, increasing from −211.7 to −303.6 kJ/mol, while the adsorption capacity of the zigzag-type char structure for NO molecules is hardly affected by Na atoms. This study provides a theoretical basis for the development of clean utilization technology of high-alkali coal.

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Sodium in high-alkali coal facilitates the heterogeneous reduction of nitrogen oxides on char surfaces. However, the reaction mechanism is unclear. In this paper, the effect of sodium on the reaction path of the char heterogeneous reduction of NO was analyzed based on the first-principles study using an armchair char model and a zigzag char model separately. Four reaction paths were obtained, and the most likely reaction path was found by comparison. The highest energy barriers of the reduction reactions were reduced to some extent by doping with the sodium atom. The doped sodium atom had a significant effect on the heterogeneous reduction reactions on the surface of the armchair char and had little effect on the surface of the zigzag char. However, a comprehensive analysis showed that the reactivity of the zigzag model is better than that of the armchair model. From the thermodynamic analysis, the addition of the sodium atom could change the reaction from nonspontaneous to spontaneous. After the completion of the reaction, the oxygen atom would be immobilized on the char structure surface, which will have an effect on the subsequent reaction. This study revealed the effect of the sodium atom on the reaction mechanism of the char heterogeneous reduction of NO and helped perfect the mechanism of the char heterogeneous reduction of NO.

Purpose To describe the prevalence and analyse the associated factors of possible sarcopenia and sarcopenia among community-dwelling old adults in China, in order to provide effective strategies for early prevention and treatment of sarcopenia. Methods This cross-sectional study evaluated community-dwelling old adults aged over 60 years. The basic information, morphological indices, body composition, physical activities were collected and assessed. Possible sarcopenia and sarcopenia were diagnosed by the criteria of Asian Working Group for Sarcopenia (AWGS) in 2019. A multivariate logistic regression model with stepwise method was employed to identify factors associated with possible sarcopenia and sarcopenia. Results In total 729 old adults from Tianjin were included in this study. Eighty-one participants were diagnosed with possible sarcopenia (prevalence of 11.11%). Seventy-five participants were diagnosed with sarcopenia (prevalence of 10.29%). Age (odds ratio (OR):1.047, 95% confidence interval (CI): 1.055–1.090) and lower physical activities (low level OR:4.171, 95% CI:1.790–9.720; medium level OR:2.634, 95% CI:1.352–5.132) were significantly associated with possible sarcopenia. Age (OR:1.187, 95% CI:1.124–1.253), higher body fat percentage (OR:1.225, 95% CI:1.140–1.317), lower BMI (OR:0.424, 95% CI:0.346–0.519), lower mini-mental state examination (MMSE) scores (OR:0.865,95% CI:0.781–0.958) and low physical activities (OR:4.638, 95% CI:1.683–12.782) were significantly associated with sarcopenia. Conclusion Possible sarcopenia and sarcopenia are prevalent among community-dwelling old adults in China. Ageing and lower physical activities were both associated with possible sarcopenia and sarcopenia. Old adults with sarcopenia more likely have higher body fat percentage, lower BMI and lower cognitive function compared with those without this condition.

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