Widespread reforestation before European influence on Amazonia

An estimated 90 to 95% of Indigenous people in Amazonia died after European contact. This population collapse is postulated to have caused decreases in atmospheric carbon dioxide concentrations at around 1610 CE, as a result of a wave of land abandonment in the wake of disease, slavery, and warfare, whereby the attendant reversion to forest substantially increased terrestrial carbon sequestration. On the basis of 39 Amazonian fossil pollen records, we show that there was no synchronous reforestation event associated with such an atmospheric carbon dioxide response after European arrival in Amazonia. Instead, we find that, at most sites, land abandonment and forest regrowth began about 300 to 600 years before European arrival. Pre-European pandemics, social strife, or environmental change may have contributed to these early site abandonments and ecological shifts.

Response Surface Optimized Dyeing of Kenaf Fiber in Supercritical Carbon Dioxide

Kenaf fibers were dyed with capsanthin using supercritical carbon dioxide. Response surface methodology, based on a three level and three variable small central composite design, was employed to obtain the best possible combination of dyeing time, temperature and pressure for maximum K/S value.The optimum conditions were as follows: dyeing time of 60 min, temperature of 119.99 °C and pressure of 30 MPa. Under these conditions, the K/S value was 17.54, which was similar to the value predicted by the model.