Response Surface Methodology and Genetic Algorithms Applied to Model and Optimize the Dyeing of Cotton Process with the Reactive Black 5 Dyestuff

This work aimed to combine response surface methodology and genetic algorithms to model and optimize the dyeing process to show the influences of each component in the dyeing of cotton knit to optimize its dyeing conditions. A 26 design of central composite and rotational (DCCR) was used as support to execute seventy-eight dyeings with Reactive Black 5 dyestuff (RB5) on 100% knitted cotton substrate. The impacts of various dyeing process parameters were also investigated. The concentrations of [RB5] (percent), [NaCl] (g/L), [Na2CO3] (g/L), and [NaOH] (mL/L), as well as processing time (min) and temperature (°C), were employed. The K S-1 coefficient and the costs of each experiment were calculated as a result. The objective function was derived from the fitting of the experimental points using the least-squares method and analysis of variance (ANOVA). The findings revealed that both techniques can be efficiently applied to model and optimize the cotton dyeing, with the goal of lowering the cost and environmental impact

Energy level decay and excited state absorption processes in erbium-doped tellurite glass

The fundamental excited state decay processes relating to the 4I11/2 → 4I13/2 transition in singly Er3+-doped tellurite (TZNL) glass have been investigated in detail using time-resolved fluorescence spectroscopy. Selective laser excitation of the 4I11/2 energy level at 970 nm and selective laser excitation of the 4I13/2 energy level at 1485 nm has established that energy transfer upconversion by way of a dipole-dipole interaction between two excited erbium ions in the 4I13/2 level populates the 4I11/2 upper laser level of the 3 m transition. This upconversion has been analyzed for Er2O3 concentrations between 0.5 mol. and 2.2 mol. . The 4I13/2 and 4I11/2 energy levels emit luminescence with peaks located at 1532 nm and 2734 nm, respectively, with radiative decay efficiencies of 65 and 6.8 for the higher (2.2 mol. ) concentration sample. The low 2.7 m emission efficiency is due to the non-radiative decay bridging the 4I11/2 → 4I13/2 transition and energy transfer to the OH- groups in the glass. Excited state absorption was observed to occur from the 4I13/2 and 4I11/2 levels with peak absorptions occurring at 1550 nm and 971 nm, respectively. The decay time of the 4I11/2 excited state decreased with an increase in the Er3+ concentration, which related to energy transfer to OH- ions that had a measured concentration of 6.6 1018 cm-3. Results from numerical simulations showed that a population inversion is reached at a threshold pumping intensity of ∼80 kW cm-2 for a cw laser pump at 976 nm if [Er3+] ≥ 1.2 × 1021 cm-3 (or [Er 2O3] ≥ 2.65 mol. ) without OH- impurities being present. © 2011 American Institute of Physics.Laércio Gomes, Michael Oermann, Heike Ebendorff-Heidepriem, David Ottaway, Tanya Monro, André Felipe Henriques Librantz and Stuart D. Jackso