Douglas H. Fockink

Production of cellulosic ethanol from cotton processing residues after pretreatment with dilute sodium hydroxide and enzymatic hydrolysis

In this study, production of cellulosic ethanol from two cotton processing residues was investigated after pretreatment with dilute sodium hydroxide. Pretreatment performance was investigated using a 2(2) factorial design and the highest glucan conversion was achieved at the most severe alkaline conditions (0.4g NaOH g(-1) of dry biomass and 120°C), reaching 51.6% and 38.8% for cotton gin waste (CGW) and cotton gin dust (CGD), respectively. The susceptibility of pretreated substrates to enzymatic hydrolysis was also investigated and the best condition was achieved at the lowest total solids (5wt%) and the highest enzyme loading (85mg of Cellic CTec2 g(-1) of dry substrate). However, the highest concentration of fermentable sugars - 47.8 and 42.5gL(-1) for CGD and CGW, respectively - was obtained at 15wt% total solids using this same enzyme loading. Substrate hydrolysates had no inhibitory effects on the fermenting microorganism.

Principles and Challenges Involved in the Enzymatic Hydrolysis of Cellulosic Materials at High Total Solids

The enzymatic hydrolysis of plant polysaccharides is a key unit operation for the production of cellulosic ethanol. However, hydrolysates with sugar concentrations as high as 180–200 g L−1 (18–20 °Brix) must be produced for a successful ethanol fermentation and this can only be achieved at high total solids. With this, a significant decrease in both capital and production costs is achieved. In addition, less water is needed, effluent generation is minimized and the cost of wastewater treatment is reduced. At high total solids, the rheology of biomass slurries exhibits large apparent viscosities and yield stresses that increase with the volume fraction of the insoluble solids, creating both mass and heat transfer limitations at various levels within the body of the fiber suspension. In this context, this chapter reviews the most recent developments in enzymatic hydrolysis for the production of high sugar concentrations using high total solids and low enzyme loadings. This chapter also reviews several strategies to overcome these rheological problems, such as fed-batch feeding and the addition of chemical additives that are able to decrease the effects of extremely high initial viscosities, thus facilitating the substrate liquefaction while decreasing the unproductive binding of enzymes. Lastly, a brief discussion is given about the impact of different impellers setups on the hydrolysis rate, since adequate mixing capacity and low energy consumption are key factors in designing bioreactors for lignocellulose processing.

Male-Produced Sex Pheromone of the Carrion Beetles, Oxelytrum discicolle and its Attraction to Food Sources

Carrion beetles are part of the great diversity of insects collected on cadavers. In Brazil, beetles of the genus Oxelytrum have great forensic importance in post mortem interval (PMI) estimation. We investigated the system of chemical communication in the attraction of these necrophagous beetles. Gas chromatographic analysis (GC) of female and male aeration extracts revealed the presence of two male-specific compounds, produced in a ratio of 94:6. Bioassays showed that the combination of male produced volatiles and the odor of a food source (carcass volatiles) were attractive to females. Mass and infrared spectral analyses of the male-specific compounds suggested that they were both unsaturated hydrocarbons. Several micro-derivatizations were carried out with the natural products, and the target structures were identified as (Z)-1,8-heptadecadiene (major) and 1-heptadecene (minor). The structure of the minor component was assigned by co-injection with a commercial standard. A seven-step synthesis was developed to synthesize (Z)-1,8-heptadiene, which co-eluted with the major natural product on three different GC stationary phases. Y-tube olfactometer assays showed that the mixture of synthetic standards in the naturally occurring proportion was slightly attractive to females. The results contribute both to the understanding of the chemical ecology of O. discicolle and to its potential to improve the accuracy of PMI estimation.

Effects of low concentrations of ibuprofen on freshwater fish Rhamdia quelen

Ibuprofen is a pharmaceutical drug widely used by the global population and it has been found in aquatic ecosystems in several countries. This study evaluated the effects of ibuprofen in environmental concentrations (0, 0.1, 1 and 10 μg/L) on the freshwaterspecies Rhamdia quelen exposed for 14 days. In the posterior kidney, ibuprofen increased glutathione-S-transferase activity in all groups exposed. Furthermore, increased glutathione peroxidase activity and the levels of reduced glutathione in the group exposed to 10 μg/L. Ibuprofen decreased the carbonic anhydrase activity in the posterior kidney in all exposed groups, and increased the activity in the gills in group exposed to 0.1 μg/L. The levels of plasma magnesium increased in groups exposed to 0.1 and 1 μg/L. In the blood, ibuprofen decreased the white blood cell count in groups exposed to 0.1 e 1.0 μg/L. Therefore, these results indicated that ibuprofen caused nephrotoxicity and demonstrated immunosuppressive effect in Rhamdia quelen.