Early number and arithmetic performance of Ecuadorian 4-5-year-olds

This study aimed at (a) constructing a reliable and valid test to assess Ecuadorian 4–5-year olds’ number and arithmetic skills; (b) providing empirical data on Ecuadorian 4–5-year olds’ number and arithmetic skills; and (c) confronting these children’s actual performances with the performances expected by national experts in this domain. We administered the Test of Early Number and Arithmetic (TENA), developed on the basis of the Ecuadorian mathematics standards to 86 Preschoolers and 127 Kindergartners and asked 10 experts to evaluate TENA’s validity and predict children’s performances on it. Results supported the overall reliability and validity of the TENA. Furthermore, we observed differences in number and arithmetic competencies between and within Preschoolers and Kindergartners, but not between boys and girls. Finally, experts overestimated children’s performances on the test. The scientific and practical implications of these results are discussed

Experimental Determination and Correlation of Artemisinin's Solubility in Supercritical Carbon Dioxide

The measurement and correlation of the experimental solubility of the antimalarial artemisinin (Artemisia annua L.) in supercritical carbon dioxide is reported. Results were obtained using a static analytical method at 308.2, 318.2, and 328.2 K, and in a pressure range from 10.0 up to 25.0 MPa. Solubility experimental data were correlated with three density-based models (Chrastil, Bartle, and Méndez-Santiago−Teja models) and with two cubic equation of state (EOS) models, namely, the Peng−Robinson EOS and the Soave−Redlich−Kwong EOS, together with the conventional van der Waals mixing and combining rules. Good correlation results were obtained between the calculated and the experimental solubility to all fitted models. Results clearly show the feasibility of processing this antimalarial drug using supercritical fluid technologies and processes