188 research outputs found
Int J Min Sci Technol
No full textThe environmental risks associated with casing deformation in unconventional (shale) gas wells positioned in abutment pillars of longwall mines is a concern to many in the mining and gas well industry. With the recent interest in shale exploration and the proximity to longwall mining in Southwestern Pennsylvania, the risk to mine workers could be catastrophic as fractures in surrounding strata create pathways for transport of leaked gases. Hence, this research by the National Institute for Occupational Safety and Health (NIOSH) presents an analytical model of the gas transport through fractures in a low permeable stratum. The derived equations are used to conduct parametric studies of specific transport conditions to understand the influence of stratum geology, fracture lengths, and the leaked gas properties on subsurface transport. The results indicated that the prediction that the subsurface gas flux decreases with an increase in fracture length is specifically for a non-gassy stratum. The sub-transport trend could be significantly impacted by the stratum gas generation rate within specific fracture lengths, which emphasized the importance of the stratum geology. These findings provide new insights for improved understanding of subsurface gas transport to ensure mine safety.CC999999/ImCDC/Intramural CDC HHSUnited States/2021-09-21T00:00:00Z34552806PMC84551481036
Genetic diversity and fungicide sensitivity of Rhizoctonia solani associated with soybean seedling disease
No full textRhizoctonia solani, a ubiquitous and genetically diverse fungus, is an important seedling pathogen of soybean in North America. With the dearth of commercial soybean varieties marketed for resistance to members of this species, seed treatment fungicides have become increasingly important as a management option. However, our knowledge of the groups associated with soybean seedlings, the genetic structure of the pathogenic groups, as well as their potential for adaptation to fungicide seed treatments, is very limited. To bridge this knowledge gap, we characterized, using conventional and molecular techniques, Rhizoctonia isolates collected from farmers’ fields in the U.S. and in Canada to identify the predominant and most aggressive groups. Three taxonomic groups were identified: R. solani, R. zeae, and the binucleate Rhizoctonia. The R. solani isolates comprised members of anastomosis groups (AG) 2-2IIIB, 3PT, 4 HGI, 4 HGIII, 7, and 11. Isolates of AG-2-2IIIB were the most frequently recovered and the most aggressive on soybean and corn. Using single nucleotide polymorphism markers identified from genotyping-by-sequencing approach, the genetic structure of the populations of AG-2-2IIIB from Illinois, Ohio, and Ontario was assessed for clues about the pathogen’s reproductive biology and to determine if the pattern of genetic variation within populations is consistent with that of a pathogen that is at a high risk of adapting to repeated fungicide applications. While the Illinois population was mostly clonal, the genetic structure of the AG-2-2IIIB populations from Ontario and Ohio revealed a mixed reproductive mode, suggesting the need for caution when applying fungicides. Our results also presented genotype flow as a predominant force shaping the population genetic structure of this AG. To determine if R. solani populations are becoming less sensitive to the fungicide classes commonly used to manage seedling disease, a fungicide resistance monitoring program was initiated to compare the sensitivities of historical isolates with no prior fungicide exposure to the sensitivities of isolates that have been exposed to fungicides over time. Results from fungicide sensitivity assays showed that sensitivity to the fungicide classes tested has decreased in comparison to the baseline R. solani population, but control of seedling disease caused by R. solani was still achieved regardless of in vitro sensitivity.
The appendix chapter of this dissertation presents the results of a separate study evaluating the potential of a three-gene pyramid for improved soybean aphid management . From greenhouse studies evaluating the differential reaction of soybean isolines with different combinations of aphid resistance genes, Rag1, Rag2, and Rag3 to four soybean aphid biotypes, the Rag1/2/3 pyramid was found to be the most effective.Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2018-05-01The student, Olutoyosi Ajayi, accepted the attached license on 2016-04-15 at 13:35.The student, Olutoyosi Ajayi, submitted this Dissertation for approval on 2016-04-15 at 13:50.This Dissertation was approved for publication on 2016-04-20 at 15:05.DSpace SAF Submission Ingestion Package generated from Vireo submission #9247 on 2016-07-07 at 14:16:48Made available in DSpace on 2016-07-07T21:14:47Z (GMT). No. of bitstreams: 3
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Previous issue date: 2016-04-20Embargo set by: Seth Robbins for item 93259
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Reason: Author requested closed access (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 93259
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The total synthesis of mycothiol and new inhibitors of carbohydrate processing enzymes
No full textThe work described in this dissertation covers a wide range of disciplines within organic chemistry, with the common goal of obtaining more information about various carbohydrate-processing enzymes. Carbohydrate-processing enzymes are garnering an increasing amount of attention relative to their more well-studied protein-processing counterparts, as they are ubiquitous and implicated in various regulatory, signaling and metabolic processes in eukaryotic cells. Chapter 1 involves the synthesis of anomeric phosphothioates as possible O-GlcNAc transferase inhibitors, and a mechanistic study on the anomeric Pudovik rearrangement of thiophosphites to thiophosphonates is described. Chapter 2 is an account of the development of a facile method for functionalizing 2-methyl thiazoline rings, and several selective GlcNAc-thiazoline-based O-GlcNAcase inhibitors were synthesized by this method. Chapter 3 details the 16-step total synthesis of the M. tuberculosis antioxidant carbohydrate mycothiol by a new intramolecular glycosylation method. The method is amenable to glycosylations of 2-deoxy-2-aminoglyosides, a unique aspect among such reactions. The efficiency of the synthetic route to mycothiol makes it attractive as a template from which to design analogs as potential inhibitors of enzymes involved in the biosynthesis of mycothiol. An apparently unprecedented 1,9-hydride shift is also described in the third chapter. Chapter 4 describes a tripartate prolonged-release drug delivery system, in which the drug of interest (ethynyl estradiol in this study) is coupled, through a variable linker, to another carrier drug with a long half-life and a relatively high inhibitory concentration. The effect of steric bulk on the in vitro release of ethynyl estradiol was evaluated, showing a direct relationship between steric bulk around the ester linkage and ethynyl estradiol release time. In vivo data from pigs also seemed to point to an increase in drug bioavailability with the 3-part system. Finally, chapter 5 describes early efforts to synthesize boronic acid analogs of folic acid and antifolates.Ph.D.Includes abstractVitaIncludes bibliographical referencesby Kehinde Ajay
Blood Pressure Association with Sodium Intake from Snacks Among Undergraduates of Afe Babalola University, Nigeria
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Estimating a Fiscal Reaction Function for Nigeria
No full textThe study examines the determinants of fiscal balance and the impact of the selected macroeconomic variables on the primary balance of government. It aims to estimate the fiscal reaction function for Nigeria and determine whether the implementation of fiscal policy is sustainable in the long-run. A Fiscal Reaction model was developed and ARDL technique was used to establish the relationships and interactions among the variables. The study investigated whether the fiscal measures pursued by the government from 2000:Q1 to 2018:Q4 was adequate in addressing the accumulation of huge debt. The analysis of the stylized facts reveals that the government had continued to run budget deficits for almost the entire period, except for a few period. The public debt to GDP, which is a major determinant of the primary balance, is negative and significant implying that a fiscal rule that encourages a strong reduction in debt-to-GDP levels would result in substantial pressure for Nigeria to run large primary surpluses in the future. The CUSUM and CUSUMSQ tests show the recursive residual plots of the fiscal reaction function are within the 5 per cent critical lines, hence, providing evidence of stable fiscal reaction function for Nigeria. The study thus, recommends that, apart from the urgent need for the fiscal authorities to adopt urgent reforms to discourage huge debt accumulation, improve revenue generation capacity and more fundamentally, expenditure switching to improve the quality of expenditure, the transition from primary deficits to primary surpluses should follow a gradual process
Estimating a fiscal reaction function for Nigeria
No full textThe study examines the determinants of fiscal balance and the impact of the selected macroeconomic variables on the primary balance of government. It aims to estimate the fiscal reaction function for Nigeria and determine whether the implementation of fiscal policy is sustainable in the long-run. A Fiscal Reaction model was developed and ARDL technique was used to establish the relationships and interactions among the variables. The study investigated whether the fiscal measures pursued by the government from 2000:Q1 to 2018:Q4 was adequate in addressing the accumulation of huge debt. The analysis of the stylized facts reveals that the government had continued to run budget deficits for almost the entire period, except for a few period. The public debt to GDP, which is a major determinant of the primary balance, is negative and significant implying that a fiscal rule that encourages a strong reduction indebt-to-GDP levels would result in substantial pressure for Nigeria to run large primary surpluses in the future. The CUSUM and CUSUMSQ tests show the recursive residual plots of the fiscal reaction function are within the 5 per cent critical lines, hence, providing evidence of stable fiscal reaction function for Nigeria. The study thus, recommends that, apart from the urgent need for the fiscal authorities to adopt urgent reforms to discourage huge debt accumulation, improve revenue generation capacity and more fundamentally, expenditure switching to improve the quality of expenditure, the transition from primary deficits to primary surpluses should follow a gradual process
Overview of factors that influence the adoption of mobile telephony by students in higher education institutions
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