The main objective of this research was to test the hypothesis that bioavailable protein and, more specifically, the sulfurcontaining amino acids within the protein, can be degraded by proteolytic enzymes to produce odor-causing compounds-mainly volatile sulfur compounds (VSCs)-during biosolids storage. To achieve these objectives, samples of digester effluent and cake solids were collected at 11 different wastewater treatment plants in North America, and the samples were analyzed for protein and amino acid content and general protein-degrading enzyme activity. At the same time, cake samples were stored using headspace bottles, the concentration of VSCs were measured using gas chromatography, and olfactometry measurements were made by a trained odor panel. The results showed that the bound cake protein content and methionine content was well-correlated with VSC production and the detection threshold measured by the odor panel. Water Environ. Res., 80, 127 (2008).

The main objective of this research was to test the hypothesis that bioavailable protein, and, more specifically, the sulfur-containing amino acids within the protein, can be degraded by proteolytic enzymes to produce odor causing compounds, mainly volatile sulfur compounds (VSCs), during biosolids storage. Another objective of this research was to examine the factors that affect protein and amino acid content from different full-scale treatment processes. To achieve these objectives, samples of digester effluent and cake solids were collected at 11 different wastewater treatment plants in North America and the samples were analyzed for protein and amino acid content as well as general protein degrading enzyme activity. Ten of the plants used mesophilic anaerobic digestion and one plant used thermophilic anaerobic digestion. At the same time, cake samples were stored using headspace bottles, and the concentration of VSCs were measured using GC/MS and olfactometry measurements were made by a trained odor panel. The results showed the bound cake protein content from the different sites was well correlated with VSC production as well as the detection threshold (DT) measured by the odor panel. In addition, the sulfur containing amino acid, methionine, was very well correlated with the VSC concentration and well correlated with DT. Protein degrading enzyme activity was not well correlated to odorant production. Operational parameters such as solids retention time generally did not correlate well with the biochemical constituents. However, the total iron content of a digester was negatively correlated with the bound protein concentration, suggesting greater amounts of Fe in the biosolids decreased the amount of protein that could be extracted from the cake.

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A physical chemistry lab for undergraduate students described in this report is about applying kinetic models to analyze the spread of COVID-19 in the United States and obtain the reproduction numbers. The susceptible-infectious-recovery (SIR) model and the SIRvaccinated (SIRV) model are explained to the students and are used to analyze the COVID-19 spread data from U.S. Centers for Disease Control and Prevention (CDC). The basic reproduction number R0 and the real-time reproduction number Rt of COVID-19 areextracted by fitting the data with the models, which explains the spreading kinetics and provides a prediction of the spreading trend in a given state. The procedure outlined here shows the differences between the SIR model and the SIRV model. The SIRV model considers the effect of vaccination which helps explain the later stages of the ongoing pandemic. The predictive power of the models is also shown giving the students some certainty in the predictions they made for the following months.

Homogenates of rat kidney cortex obtained 1,3 or 14 days after a single injection of HgCl2 were used to prepare the post-microsomal pH5 supernatant fraction. The activity of this fraction for peptide synthesis from [14C]phenylalanyl-tRNA was significantly increased at 1 and 3 days, at which time the proximal tubules are regenerating [Cuppage & Tate (1967) Am. J. Pathol. 51, 405-429]. This increased activity could not be attributed to a decreased inhibitory activity, but was due to an increased aminoacyl-tRNA binding, i.e. elongation-factor-1 activity, in the supernatant fraction.