Two groups of Chinese four-year-olds and their parents' interaction in joint activities were analyzed and compared. The children in Group 1 were high scorers in written number skills and the children in Group 2 were low scorers. Eighty-five dyads participated in four separate 15-minute joint activities such as book reading, mathematical worksheets, blank paper and blocks. A mini-questionnaire was also administered. The results indicated that a wide variety of mathematics and interactive strategies were involved in the activities, that there was no difference in the frequency of mathematical events occurring in the activities between the two groups, that more parents in Group 1 used several more positive strategies than the parents in Group 2, that more children in Group 2 had trouble remaining engaged in the activity, and that the frequency and the quality of parent-child joint activities at home, such as book reading and mathematical worksheets, were possible contributors to children's development of mathematics.

Yttria in Pt/TiO2 catalyst improved the Pt dispersion and stabilized the structure, and hence enhanced the low-temperature activity and stability.

CuCe-SAPO-34 (CuCe-x) catalysts with 3 wt% Cu and various contents of Ce for selective catalytic reduction of NO x by NH 3 (NH 3 -SCR) were prepared by wet co-impregnation method. The activities of CuCe-x catalysts were better than that of Cu-SAPO-34 (Cu). In addition, hydrocarbons (HCs) resistance of the CuCe-x catalysts was examined and compared to that of Cu catalyst. The NH 3 -SCR performance after UV-vis-DRS and H 2 -TPR results confirmed that the addition of Ce could inhibit the aggregation of CuO crystallites and increase the amount of isolated copper ions. Furthermore, the NH 3 -TPD and TGA results demonstrated that the addition of Ce decreased the amount and strength of strong acid sites, so that the amounts of C 3 H 6 /O 2 adsorption on CuCe-x catalysts were lower than that on Cu catalyst. Therefore, activity and HCs resistance of Cu-SAPO-34 was improved by the addition of Ce.