Thesis advisor: Jianmin Gao / Thesis advisor: Eranthie Weerapana / Cysteine residues are known to perform an array of functional roles in proteins, including nucleophilic and redox catalysis, regulation, metal binding, and structural stabilization, on proteins across diverse functional classes. These functional cysteine residues often display hyperreactivity, and electrophilic chemical probes can be utilized to modify reactive cysteines and modulate their protein functions. A particular focus was placed on three peptide-based cysteine-reactive chemical probes (NJP2, NJP14. and NJP15) and their particular biological applications. NJP2 was discovered to be an apoptotic cell-selective inhibitor of glutathione S-transferase omega 1 and shows additional utility as an imaging agent of apoptosis. NJP14 aided in the development of a chemical-proteomic platform to detect Zn2+-cysteine complexes. This platform identified both known and unknown Zn2+-cysteine complexes across diverse protein classes and should serve as a valuable complement to existing methods to characterize functional Zn2+-cysteine complexes. Finally, NJP15 was part of a panel of site-selective cysteine-reactive inhibitors of protein disulfide isomerase A1 (PDIA1). These inhibitors show promise in clarifying the unique and redundant properties of PDIA1's dual active-sites, as well as interrogating the protein's role in cancer. Together, these case studies illustrate the potential of cysteine-reactive chemical probes to modulate protein activities, interrogate biological systems, and aid in the development of powerful therapeutic drugs. / Thesis (PhD) — Boston College, 2015. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

Neste trabalho é utilizado o processo oxidativo avançado, via reagente de Fenton, para a destruição de resíduos que contenham hidroquinona. Sendo as técnicas utilizadas para a comprovação desta metodologia: ultravioleta, carbono orgânico total, cromatografia gasosa, cromatografia gasosa acoplada à espectrometria de massas. Em todas essas análises pôde?se observar uma destruição de mais de 60% da hidroquinona. / In this work, the destruction of hydroquinone present in residues was reached through advanced oxidation process, via Fenton. The reaction was followed by ultraviolet spectroscopy, total organic carbon and gas chromatography with flame ionization detector and mass spectrometry detector. Throughout all the results, the destruction of hydroquinone was greater than 90%.

Graduation date: 1995

A billion tons per year of genetically modified corn residues are soil incorporated having both direct and indirect effects on the belowground environment, soil carbon (C) sequestration, and nutrient cycling. If Bt genetic modification has non-target effects on corn stover structural/non-structural carbohydrate and nitrogen (N) concentrations, then the degradation rate of Bt-corn stover may be different than that of non-Bt isolines, possibly influencing soil C storage and N mineralization. Thus, this research focused primarily on the comparison of C and N mineralization of corn stover in soil as affected by Bt-trait, plant portion, water-availability and HFC-trait; and secondarily on the existence of Bt-related variations in the chemical structure of corn residues that might affect the degradation rate of stover in soil and consequently the soil C and N dynamics. A laboratory experiment was conducted under non-limiting N conditions with stover of Bt/non-Bt isogenic pairs of two varieties, a ?high fermentable corn? (HFC) line harvested at Snook, Texas and a non-HFC corn line harvested at the irrigated field of Snook and the non-irrigated field of College Station, Texas. The stover was partitioned into three plant portions, incorporated into a Weswood soil and incubated during 223 days. Results showed that the differences observed in the degradation in soil of Bt vs. non-Bt corn stover were dependent on environmental conditions (irrigated vs. non-irrigated settings) and hybrid variety (HFC vs. non-HFC hybrid lines). The structural composition of corn plants was affected by the Bt-trait, HFC-trait, irrigation and their interactions. Variations in the biomass fractions of the initial stover of Bt and non-Bt hybrids had minimum to non-impact on soil C and N concentrations measured at the end of the 223-day incubation period. Lignin concentration was affected by a Bt-trait*variety interaction. There were no significant differences in lignin concentration between non-Bt/Bt-corn derived stovers of the non-HFC variety irrespective of irrigation regime but Bt-hybrids of the HFC variety contained more than twice as much lignin as the non-Bt isogenic plants. The effects of higher lignin concentration on C mineralization rate appeared to be offset by an increased lignin degradability inherent in HFC-trait. Overall, results indicated that the cultivation of Bt-modified maize lines is not likely to have significant effects on soil C or N dynamics compared with the cropping of non-Bt hybrids.

In the United Sates and around the world, electric power plants are among the biggest sources of greenhouse gas emissions which the Intergovernmental Panel on Climate Change argued was the main cause of climate change and global warming. This dissertation explores the factors which may induce electricity producers to use biomass fuels for power generation and thereby mitigate the impact of greenhouse gas emissions. Analyses in this dissertation suggest that there are two important factors which will play a major role in determining the future degree of bioelectricity production: the price of coal and the future price of carbon emissions. Using The Forest and Agricultural Sector Optimization Model—Green House Gas version (FASOMGHG) in a case study examining the competitiveness of crop residues, this dissertation finds that crop residues currently cost much more than coal as an electricity generation feedstock because they have lower heat content and higher production /hauling costs. For them to become cost competitive with coal, the combined costs of production and hauling must be cut by more than half or the coal price needs to rise. In particular, for crop residues to have any role in electricity generation either the price of coal has to increase to about $43 per ton or the carbon equivalent price must rise to about $15 per ton. The simulation results also show that crop residues with higher heat content such as wheat residues will have greater opportunities in bioelectricity production than the residues with lower heat content. In addition, the analysis shows that improvements in crop yield do not have much impact on bioelectricity production. However, the energy recovery efficiency does have significant positive impact on the bioelectricity desirability but again only if the carbon equivalent price rises substantially. The analysis also shows the desirability of cofiring biomass as opposed to 100% replacement because this reduces haling costs and increases the efficiency of heat recovery. In terms of policy implications, imposing carbon emission restrictions could be an important step in inducing electric power producers to include biofuels in their fuelmix power generation portfolios and achieve significant greenhouse gas emission reductions.

A billion tons per year of genetically modified corn residues are soil incorporated having both direct and indirect effects on the belowground environment, soil carbon (C) sequestration, and nutrient cycling. If Bt genetic modification has non-target effects on corn stover structural/non-structural carbohydrate and nitrogen (N) concentrations, then the degradation rate of Bt-corn stover may be different than that of non-Bt isolines, possibly influencing soil C storage and N mineralization. Thus, this research focused primarily on the comparison of C and N mineralization of corn stover in soil as affected by Bt-trait, plant portion, water-availability and HFC-trait; and secondarily on the existence of Bt-related variations in the chemical structure of corn residues that might affect the degradation rate of stover in soil and consequently the soil C and N dynamics. A laboratory experiment was conducted under non-limiting N conditions with stover of Bt/non-Bt isogenic pairs of two varieties, a ?high fermentable corn? (HFC) line harvested at Snook, Texas and a non-HFC corn line harvested at the irrigated field of Snook and the non-irrigated field of College Station, Texas. The stover was partitioned into three plant portions, incorporated into a Weswood soil and incubated during 223 days. Results showed that the differences observed in the degradation in soil of Bt vs. non-Bt corn stover were dependent on environmental conditions (irrigated vs. non-irrigated settings) and hybrid variety (HFC vs. non-HFC hybrid lines). The structural composition of corn plants was affected by the Bt-trait, HFC-trait, irrigation and their interactions. Variations in the biomass fractions of the initial stover of Bt and non-Bt hybrids had minimum to non-impact on soil C and N concentrations measured at the end of the 223-day incubation period. Lignin concentration was affected by a Bt-trait*variety interaction. There were no significant differences in lignin concentration between non-Bt/Bt-corn derived stovers of the non-HFC variety irrespective of irrigation regime but Bt-hybrids of the HFC variety contained more than twice as much lignin as the non-Bt isogenic plants. The effects of higher lignin concentration on C mineralization rate appeared to be offset by an increased lignin degradability inherent in HFC-trait. Overall, results indicated that the cultivation of Bt-modified maize lines is not likely to have significant effects on soil C or N dynamics compared with the cropping of non-Bt hybrids.

In Ghana, wastewater is frequently used as a source of irrigation water for crops in urban areas, due to water scarcity and an increasing population growth. The water contains high amounts of nutrients, but also other unwanted constituents such as heavy metals, pathogens and pharmaceutical residues and is a potential health risk for the consumers. This study aimed to determine the status of pharmaceutical pollution in irrigation water used in Chirapatre Estates, a suburb to Kumasi, Ghana. Chirapatre Estates is located on a hill sloping towards a stream, with a network of sewer lines connected to a Waste Stabilization Pond (WSP). Problems regarding disposal of pharmaceutical waste, frequently used medications in the area and water quality of irrigation water was analyzed through interviews and water analysis. The interviews were made with households, farmers and pharmacies and the water samples were collected at farms and the maturation pond, the final treatment in the WSP. The analysis focused on the water quality parameters; pH, Chemical Oxygen Demand (COD), Total Suspended Solids (TSS), total phosphorus, phosphate, total nitrogen and nitrate. The empirical study showed high use of malaria treatment medication and paracetamol for adults as well as children. No instructions of disposal of unused medications were expressed through the pharmacy or by the government, causing the majority of the inhabitants to dispose their leftovers in the trash. One can speculate that there might be a possible risk of finding some pharmaceutical residues in the aquatic environment, especially for the types of pharmaceuticals that can be persistent. The results indicated that the water quality from the WSP and at the farming sites was acceptable when compared to the Ghana Environmental Protection Agency (EPA) guidelines, except for TSS and total phosphorus. Further treatment of the water is still suggested, since adjacent farms use the water frequently and the EPA guidelines are not fulfilled. Future studies are recommended to establish the pharmaceutical residues present in the stream water.

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