Synthesis of model oxepin substrates for comparative two electron oxidation studies with cytochrome P450 and cerium ammonium nitrate to investigate benzene metabolism

Two model oxepins were synthesized in an attempt to model the metabolism of benzene in the human liver. 4,5-Benzoxepin was subjected to similar enzyme reactions that the oxepin metabolite itself would encounter if one was exposed to benzene. In addition, a synthesis of 2,3-benzoxepin was completed in order to compare enzyme and non-enzyme catalyzed reactions with that of 4,5-benzoxepin. In an attempt to test the validity of the enzyme reactions, the model oxepins were also reacted with a two single electron oxidizing inorganic salt, cerium (IV) ammonium nitrate (CAN) to see if the intermediates following the enzyme reaction were consistent. Other chemists in the past have postulated that oxepin undergoes further epoxidation in metabolism instead of two single electron oxidations, so a test with dimethyldioxirane (DMDO) was also performed on the model oxepins to observe if their products closer matched the enzyme reactions. Research suggests that oxepin can follow both the two single electron oxidation and further epoxidation metabolic pathways when exposed to enzymes CYP1A2 and CYP3A4 under multiple concentrations of enzyme with a fixed concentration of model oxepin substrate. Amides and lactams are common structural motifs found in a variety of natural products and construct the backbone of amino acid chains, proteins, and enzymes. Amides have 3 major resonance contributors. 4-Silatranones have been calculated previously to have the nitrogen lone pair delocalized like in normal amides vs. having a coordinate covalent bond with silicon as in silatranes, which is a bridged bicyclic amine dependent upon conformation. This research aims to synthesize strained lactams known as 4-silatranones and to help elucidate who wins the competition for nitrogen’s lone pair-the silicon via dative bond or delocalization into the amide carbonyl. Iron chelators have many biological applications including the treatment of iron overload disease, the suppression or promotion of reactive oxygen species production and even the ability to sense the iron status in the cell. Development of a chelator that can modulate and sense intracellular iron is the goal of this research. 8-hydroxyquinoline has been shown as a powerful chelating agent for iron in the past when three equivalents of 8-hydroxyquinoline have been tethered to a tripodal linker allowing for a hexadentate chelator to completely sequester iron. This portion of the project focuses on the synthesis of a tripodal linker with a carboxylic acid handle (Figure 4) to attach the chelator to lysine residue of a SS-peptide (synthesized by a research group member) that targets the mitochondria of a cell which contain labile iron pools

Microstructure and conductance-slope of InAs/GaSb tunnel diodes

InAs/GaSb and similar materials systems have generated great interest as a heterojunction for tunnel field effect transistors (TFETs) due to favorable band alignment. However, little is currently understood about how such TFETs are affected by materials defects and nonidealities. We present measurements of the conductance slope for various InAs/GaSb heterojunctions via two-terminal electrical measurements, which removes three-terminal parasitics and enables direct study on the effect of microstructure on tunnelling. Using this, we can predict how subthreshold swings in TFETs can depend on microstructure. We also demonstrate growth and electrical characterization for structures grown by metalorganic chemical vapor deposition (MOCVD)—a generally more scalable process compared with molecular beam epitaxy (MBE). We determine that misfit dislocations and point defects near the interface can lead to energy states in the band-gap and local band bending that result in trap-assisted leakage routes and nonuniform band alignment across the junction area that lower the steepness of the conductance slope. Despite the small lattice mismatch, misfit dislocations still form in InAs on GaSb due to relaxation as a result of large strain from intermixed compositions. This can be circumvented by growing GaSb on InAs, straining the GaSb underlayer, or lowering the InAs growth temperature in the region of the interface. The conductance slope can also be improved by annealing the samples at higher temperatures, which we believe acts to annihilate point defects and average out major fluctuations in band alignment across the interface. Using a combination of these techniques, we can greatly improve the steepness of the conductance slope which could result in steeper subthreshold swings in TFETs in the future.National Science Foundation (U.S.). Center for Energy Efficient Electronics Science (Award 0939514)Natural Sciences and Engineering Research Council of Canada (Postgraduate M Scholarship

The impact of firm characteristics on speed of adjustment to target leverage: a UK study

Responding to the need to investigate heterogeneity in the speed of adjustment (SOA) to target leverage in a manner that reflects the fractional nature of leverage, we estimate SOA across sub-samples of UK firms using the Dynamic Panel Fractional (DPF) estimator. Using firm characteristics to identify firms subject to varying costs of deviation from and adjustment to target leverage, we find significant evidence of heterogeneity in the speeds at which UK firms adjust to target leverage. Our results show that small, high growth and low dividend paying firms adjust to target leverage faster than their large, low growth and high dividend paying counterparts. We also find some evidence to suggest openly held firms adjust faster than closely held firms, though our results are not robust to the categorizing criterion employed or target leverage specification

Pathways for Nutrient Loss to Water; Slurry and Fertilizer Spreading

End of project reportThere are almost 150,000 farms in Ireland and these contribute substantial quantities of N and P to inland and coastal waters. Some of these nutrients are carried from wet soils by overland flow and by leaching from dry soils. Farm practice can reduce the loss from farms by judicious management of nutrients. Improvements are required to diminish export of nutrients without impairing operations on the farm. Literature regarding nutrient loss from agriculture was reviewed in this project and maps were prepared to predict best slurry spreading times around Ireland. Two further maps were prepared to show slurry storage requirement on farms

The development of feeding and management strategies for milk production systems with very contrasting milk supply patterns.

End of Project ReportsIn Experiment 1, three systems of milk production with contrasting calving patterns, namely 100% autumn (A); 100% spring (S) and 50% autumn: 50% spring (AS), were compared over a two year period. The average milk yield was 6,532, 6,358 and 6,142 kg/cow for systems A, AS and S respectively. The difference in yield was not statistically significant. Fat yield, fat content and protein yield for system S was significantly lower than those with the other two systems. The autumn-calving cows (A) had reduced reproductive performance. Experiment 2 compared grazed grass with grass silage as a forage source for autumn-calving cows in early lactation; it showed that the cows on grazed grass had significantly higher milk protein yield and milk protein content. The cows on the grass silage had significantly lower dry matter intake and a significantly higher bodyweight loss post-calving. The aim of this project was to develop low-cost systems of milk production which lead to an improved milk supply pattern of quality milk for the food industry. In particular, the objective was to research the role which grazed grass can contribute to the feed requirements of cows calving at different times during the year.European Union Structural Funds (EAGGF

Pulpits and Platforms: The Role of the Church in Determining Protest among Black Americans

This article further specifies the relationship between church-based resources, group identification and political activism among black Americans. Previous research indicates that political communication within churches and activism within the church serve to motivate political participation. Our research suggests that, net of relevant controls, activism within the church does not significantly increase protest politics. A key determinant of protest participation is attending a church that exhibits a politicized church culture, and this effect is contingent upon educational attainment and membership in secular organizations.Hence, the church serves as a crucial context for the dissemination of political messages and exposure to opportunities for protest only for those black Americans with relatively low educational achievement and organizational involvement. Group identification has no effect on protest participation

Heterogeneity in the Speed of Adjustment to Target Leverage: A UK Study

Responding to the need to address heterogeneity in the speed of adjustment (SOA) to target leverage in a manner that reflects the fractional nature of leverage, we estimate SOAs across sub-samples of UK firms using the Dynamic Panel Fractional estimator (DPF). Using firm risk as a categorising variable, we show that riskier firms tend to adjust to target leverage at a faster rate, suggesting opportunity costs of being away from target leverage are higher for riskier firms. We also demonstrate the bias in SOAs as estimated using a model that does not account for the fractional nature of leverage, and show that this bias can result in spurious inferences being made when comparing SOAs across sub-samples. Our results cast doubt on existing evidence relating to heterogeneity in SOAs of UK firms