The rapid decrease of CO2 capture capacity is one of the most challenging problems hindering the use of naturally occurring limestone in the calcium looping process. In this work, the mechanical modification method (dry planetary ball milling) was used to improve the cyclic CO2 capture performance of naturally occurring limestone. Low-cost Bayer aluminum hydroxide sourced from the industrial-scale production of alumina from bauxite ore was used as the precursor of the inert support to enhance the CO2 sorption stability of the ball-milled sorbents. It was found that the CO2 uptake of the milled sorbents could be further improved by increasing the ball-milling time because this generated more amounts of fine particles. Moreover, the pellets produced from ball-milled limestone powder possessed a relatively high CO2 capture capacity of 0.252 g/g in the 25th cycle, which is nearly 1.3 times the capture capacity of naturally occurring limestone powder. This indicates that the combination of mechanical modification and pelletization is an effective approach to produce highly efficient CO2 capture pellets from naturally occurring limestone.

This cross-cultural study investigated country differences in the relationship between maternal parenting styles and two important developmental outcomes of students – high school achievement and self-esteem. 634 undergraduates resident in three countries (China 207, Turkey 196, USA 231) where socio-cultural orientation and previous research suggest that normative family relationships would be different, were selected. We predicted that in the three countries, different maternal parenting styles would be prevalent and would foster positive development in terms of their congruence with the prevailing individualistic or collectivist ethic of the country. Students completed Buri’s Parent Authority Questionnaire (which yielded scores on maternal authoritarian, authoritative and permissive parenting), Rosenberg’s selfesteem scale, and reported on their high school achievement. Results showed country differences in the prevalence of the three maternal parenting styles, and some differences in the way each parenting style was related to student outcomes. Nevertheless, most differences were not those predicted. In particular, the Chinese findings were unexpected, as the Chinese mothers were the most authoritative, and were the only group for whom authoritarian parenting was negatively associated with high school achievement. Reasons for the unpredicted results are discussed as well as the need for changes in the conceptualization of parenting to accommodate diverse and diversifying cultures. Some novel findings from Turkey suggest the advantages of studying parenting in a wider range of countries to reveal the variety of family processes that contribute to positive child development.

No abstract

The intrinsic kinetics of char combustion were commonly investigated using thermogravimetric analysis (TGA) in previous works at low temperatures to prevent oxygen limitations and temperature deviation. However, the low temperatures caused excess test time because the reaction rate was too slow. In this study, the microfluidized bed (MFB), which has effective heat and mass transfer, was used to investigate the intrinsic kinetics of char combustion at a higher temperature within less time. TGA was used to check the reliability of the MFB. The results suggested that, for fine particles (74–100 μm), the particle temperature deviation and gas distortion could be disregarded in the MFB. For four coal samples, the activation energy measured by the MFB was similar to the result measured by TGA, but the test time using the MFB was greatly shortened as a result of the higher temperatures. The kinetic parameters measured by the MFB were used to predict the char oxidation rate. The predicted rate fit the TGA experiment well at lower temperatures. These results demonstrated the reliability of the MFB and TGA measurements. However, at higher temperatures, the combustion rate in TGA was limited by oxygen diffusion, suggesting that the TGA measurement should be carried out at relatively low temperatures to prevent oxygen diffusion limitation. Instead, the MFB measurement was still valid at higher temperatures as a result of the effective mass and heat transfer.

Many countries have been implementing various control measures with different strictness levels to prevent the coronavirus disease 2019 (COVID-19) from spreading. With the great reduction in human mobility and daily activities, considerable impacts have been imposed on the global air transportation industry. This study applies a hybrid SARIMA-based intervention model to measure the differences in the impacts of different control measures implemented in China, the U.S. and Singapore on air passenger and air freight traffic. To explore the effect of time span for the measures to be in force, two scenarios are invented, namely a long-term intervention and a short-term intervention, and predictions are made till the end of 2020 for all three countries under both scenarios. As a result, predictive patterns of the selected metrics for the three countries are rather different. China is predicted to have the mildest economic impact on the air transportation industry in this year in terms of air passenger revenue and air cargo traffic, provided that the control measures were prompt and effective. The U.S. would suffer from a far-reaching impact on the industry if the same control measures are maintained. More uncertainties are found for Singapore, as it is strongly associated with international travel demands. Suggestions are made for the three countries and the rest of the world on how to seek a balance between the strictness of control measures and the potential long-term industrial losses.