RESUMEN
Biofuel is one of the best ways to reduce our dependence on fossil fuels. Ever since commercial biodiesel production began, waste glycerol, the biodiesel byproduct, has gained researchers’ interest, especially its recycling. Here, we explored using glycerol residue (carbon source) as a substrate in the fermentation process for ethanol production by Escherichia coli K12 in anaerobic conditions. The factors affecting the ethanol production was optimised by response surface methodology (RSM). Significant variables that impact the ethanol concentration were pH, temperature and the substrate, with a statistically significant effect (P <0.05) on ethanol formation. The significant factor was analyzed by the Box-Behnken design. The optimum conditions for bioethanol formation using glycerol as substrate was obtained at pH 7 and temperature 37°C. The ethanol productivity was 0.77 g/L/h. The ethanol concentration of 9.2 g/L achieved from glycerol residue was close to the theoretical value with the fermentation achieved at optimised terms.
RESUMEN
Purpose: To describe the variables that may be utilized in the optimization of three?dimensional heads?up surgeries (3D?HUS) for achieving better ergonomics among ophthalmic surgeons. Methods: A cross?sectional study was conducted at the operating room of a tertiary eye care center, equipped with an ARTEVO 800 3D surgical microscope and display monitor. The parameters noted were monitor height (MH), surgeon eye?to?floor distance (ETFD), surgeon eye?to?monitor distance (ETMD) and viewing tilt (VT) angle. The neck and eye strain of the surgeon and assistant were scored as per Borg’s CR?10 scale, before and after surgeries. Results: Thirty (13 right, 17 left) eye surgeries were analyzed. The minimum ETMD was 51 inches (in) and the eye strain reduced with shorter ETMD (within the range 51 inches to 83 inches). The VT and ETFD were higher for right eye surgeries. The optimum MH was between 50 and 55 in. Overall, the neck strain and eye strain were in the range of 0–3 and 0–1, respectively. Conclusion: The various parameters affecting the 3D image quality, neck and eye strain are chair height, VT angle, eye centration, monitor distance, laterality of the eye, and room illumination.