ABSTRACT
Although there is a body of work investigating code-switching (alternation between two languages in production) in the preschool period, it largely relies on case studies or very small samples. The current work seeks to extend extant research by exploring the development of code-switching longitudinally from 31 to 39 months of age in two distinct groups of bilingual children: Spanish-English children in San Diego and French-English children in Montréal. In two studies, consistent with previous research, children code-switched more often between than within utterances and code-switched more content than function words. Additionally, children code-switched more from Spanish or French to English than the reverse. Importantly, the factors driving the rate of code-switching differed across samples such that exposure was the most important predictor of code-switching in Spanish-English children whereas proficiency was the more important predictor in French-English children.
ABSTRACT
In the present study, the characteristics of leachate generated from dumpsite called 'Zapote' located in southern region of Tamaulipas, Mexico were evaluated. The adsorption of non-biodegradable organic matter measured as chemical oxygen demand (COD), color and heavy metals from leachate on activated carbon (AC) prepared in acid media from Guadua amplexifolia bamboo has been studied. In addition, the computation of kinetic parameters during the adsorption process as well as the most probable mechanisms was determined. The ACs were analyzed by using scanning electron microscopy and Fourier transform infrared spectroscopy. The experimental data showed that the ACs removed up to 81.4% of color and reduced COD up to 91.6% after 9â h of reaction at 60°C. For heavy metals, the maximum adsorption uptake was achieved at pH = 8.0 within 20â min with removal percentages of 87.0% (Pb(II)), 43.0% (Cu(II)) and 30.5% (Ni(II)). A pseudo-second-order model explained the adsorption kinetics most effectively for Pb, Ni and Cu, while a pseudo-first order was found for Zn. The AC synthesized from the G. amplexifolia species could be potentially used as an effective adsorbent in the reduction of COD, and removal of color and heavy metals.
