HYDROALLYLATION OF 1,3-DIENES CATALYZED BY RHODIUM AND NICKEL COMPLEXES

I. Design and Synthesis of Chiral Carbodicarbene LigandsThe design and synthesis of a series of chiral carbodicarbene ligands is reported. A rhodium-carbodicarbene complex was synthesized and a crystal structure was obtained. This complex is an active catalyst for the enantioselective hydroarylation of 1,3-dienes, giving 98% conversion, 8:1 rr, and 89:11 er.II. (CDC)-Rh Catalyzed Hydroallylation of 1,3-Dienes with Allyl TrifluoroboratesThe Rh-catalyzed hydroallylation of 1,3-dienes with potassium allyltrifluoroborate is reported. This reaction utilizes a bidentate carbodicarbene ligand and is tolerant of a wide range of aryl-substituted dienes in good yield (up to 76%) and selectivity (up to >20:1). Deuterium-labelling studies were performed and a bidentate carbodicarbene-rhodium complex was synthesized.III. Enantio- and Diastereoselective Ni-Catalyzed Hydroallylation of 1,3-DienesThe diastereo- and enantioselective hydroallylation of 1,3-dienes with allylboronic esters facilitated by a nickel-phosphoramidite catalyst is reported. Products are formed in high yield, regioselectivity, (E/Z)-selectivity, diastereoselectivity, and enantioselectivity (up to 87% yield, >99:1 rr, >95:5 E/Z, >98:2 dr, and 99:1 er).Doctor of Philosoph

The terrestrial carbon budget of South and Southeast Asia

Accomplishing the objective of the current climate policies will require establishing carbon budget and flux estimates in each region and county of the globe by comparing and reconciling multiple estimates including the observations and the results of top-down atmospheric carbon dioxide (CO2) inversions and bottom-up dynamic global vegetation models. With this in view, this study synthesizes the carbon source/sink due to net ecosystem productivity (NEP), land cover land use change (ELUC), fires and fossil burning (EFIRE) for the South Asia (SA), Southeast Asia (SEA) and South and Southeast Asia (SSEA=SA+SEA) and each country in these regions using the multiple top-down and bottom-up modeling results. The terrestrial net biome productivity (NBP=NEP-ELUC-EFIRE) calculated based on bottom-up models in combination with EFIRE based on GFED4s data show net carbon sinks of 217±147, 10±55, and 227±279 TgC yr?1 for SA, SEA, and SSEA. The top-down models estimated NBP net carbon sinks were 20±170, 4±90 and 24±180 TgC yr?1. In comparison, regional emissions from the combustion of fossil fuels were 495, 275, and 770 TgC yr?1, which are many times higher than the NBP sink estimates, suggesting that the contribution of the fossil fuel emissions to the carbon budget of SSEA results in a significant net carbon source during the 2000s. When considering both NBP and fossil fuel emissions for the individual countries within the regions, Bhutan and Laos were net carbon sinks and rest of the countries were net carbon source during the 2000s. The relative contributions of each of the fluxes (NBP, NEP, ELUC, and EFIRE, fossil fuel emissions) to a nation’s net carbon flux varied greatly from country to country, suggesting a heterogeneous dominant carbon fluxes on the country-level throughout SSEA

The terrestrial carbon budget of South and Southeast Asia

This is the final version of the article. Available from IOP Publishing via the DOI in this record.Accomplishing the objective of the current climate policies will require establishing carbon budget and flux estimates in each region and county of the globe by comparing and reconciling multiple estimates including the observations and the results of top-down atmospheric carbon dioxide (CO2) inversions and bottom-up dynamic global vegetation models. With this in view, this study synthesizes the carbon source/sink due to net ecosystem productivity (NEP), land cover land use change (E LUC), fires and fossil burning (E FIRE) for the South Asia (SA), Southeast Asia (SEA) and South and Southeast Asia (SSEA = SA + SEA) and each country in these regions using the multiple top-down and bottom-up modeling results. The terrestrial net biome productivity (NBP = NEP - E LUC - E FIRE) calculated based on bottom-up models in combination with E FIRE based on GFED4s data show net carbon sinks of 217 ±147, 10 ±55, and 227 ±279 TgC yr-1 for SA, SEA, and SSEA. The top-down models estimated NBP net carbon sinks were 20 ±170, 4 ±90 and 24 ±180 TgC yr-1. In comparison, regional emissions from the combustion of fossil fuels were 495, 275, and 770 TgC yr-1, which are many times higher than the NBP sink estimates, suggesting that the contribution of the fossil fuel emissions to the carbon budget of SSEA results in a significant net carbon source during the 2000s. When considering both NBP and fossil fuel emissions for the individual countries within the regions, Bhutan and Laos were net carbon sinks and rest of the countries were net carbon source during the 2000s. The relative contributions of each of the fluxes (NBP, NEP, E LUC, and E FIRE, fossil fuel emissions) to a nation's net carbon flux varied greatly from country to country, suggesting a heterogeneous dominant carbon fluxes on the country-level throughout SSEA.This research was partly supported by the NASA Land Cover and Land Use Change Program (NNX14AD94G) and the US National Science Foundation (No. NSF-AGS-12-43071)

Precipitation Impacts on Groundwater Levels in the Ephemeral Holgate Lake: A MODFLOW Inquiry

Holgate Lake, an ephemeral lake located in southeast Portland, has a history of flooding and inundating residential areas. The appearance of the lake is hypothesized to be a function of precipitation-driven changes in groundwater levels. A model was developed using MODFLOW-NWT, a U.S. Geological Survey (USGS) modular hydrologic program, to analyze parameters contributing to the appearance of the lake. The model was most sensitive to changes in aquifer properties including hydraulic conductivity and storativity. The model displayed low sensitivity to changes in precipitation, evapotranspiration, and conductance of surface waters. Results from the analysis contribute to a better understanding of the surface-groundwater system, and could be used to assess flooding risks in the Holgate Lake area with additional model calibration

A numerical study of surface air temperature response to vertical mixing and momentum extraction by wind farms and the impacts of wind farms on mesoscale boundaries

Wind turbines have been shown to impact their local microclimate. With the increasing areal coverage of wind farms it has become increasingly important to answer scientific questions regarding these impacts. In this thesis, a high resolution numerical model is employed to explore the response of land surface and near surface air temperatures within and in the immediate vicinity of large wind farms in west central Texas to changes in the turbines’ thrust and TKE coefficients during meteorological summers. A control run with no wind turbines is compared to three experimental tests, each with differing thrust and TKE coefficients. The experimental tests are fist compared to observed data from the Moderate Resolution Imaging Spectroradiometer (MODIS) data on the Terra and Aqua Satellites. It is shown that the observed impact of wind farms is greater than the numerically modeled impact. Second, the control run is compared to the experimental tests. The non-linear interaction of hub height wind speeds, thrust coefficients, and TKE coefficients along with the wind turbine layer static stability determine the temperature change impact. During night, statically stable conditions result in strong warming signals while during the day near-neutral conditions result in insignificant impacts. The magnitude of the signal is determined by non-linear interactions between the wind turbines’ thrust coefficient and the vertical wind speed. The high resolution numerical model is also used to analyze the propagation of mesoscale boundaries near and through the wind farm. When compared to the control run, the experimental simulation shows an acceleration of the propagation of the mesoscale boundaries when the boundaries approached the wind farms and a deceleration as the boundaries propagated away from the wind farms. Due to the reduction of winds by the wind farms, boundaries propagating away from the wind farms experience less winds behind the boundaries and propagation speeds are reduced. Boundaries propagating towards wind farms experience less winds ahead of the wind farms and propagation speeds increase

CE-QUAL-W2 Hydrodynamic and Water Quality Model of the Cedar River Municipal Watershed

The laterally averaged, two-dimensional model CE-QUAL-W2 was used to develop a water quality model of the Cedar River Municipal Watershed as a reservoir management and climate change scenario tool. The 90,638-acre watershed, located 56 kilometers southeast of Seattle, WA, provides drinking water to over 1.4 million people. The watershed relies on two waterbodies for storage, Chester Morse Lake and the Masonry Pool. The Masonry Dam is the main storage structure in the watershed. The Cedar River flows downstream from the Masonry Dam for 57 kilometers to Lake Washington. The reservoir model simulated Chester Morse Lake and the Masonry Pool. The river model simulated the Cedar River from the Masonry Dam for 21 kilometers to the Landsburg Diversion Dam. Model inputs included bathymetric data, stream inflows and temperatures, outflows from the Masonry Dam, water quality constituent concentrations, and meteorological data. The system was modeled over two separate time periods: January 1, 2005 to December 31, 2008 and January 1 to December 31, 2015. Water level calibration was completed by comparing observed water surface elevations in Chester Morse Lake and the Masonry Pool. Flow calibration was completed by comparing streamflow gages in the Cedar River. Water temperature calibration used temperature data from twelve locations for the 2005-2008 model and six locations for the 2015 model. Water quality calibration used data from five locations for the 2005-2008 model and ten locations for the 2015 model. The model simulated water temperature on the hourly timescale with an RMSE of 0.60-0.65°C in the reservoir models and an RMSE of 0.48-0.71°C in the river models. The model simulated dissolved oxygen profile concentrations in Chester Morse Lake with an RMSE of 0.51-0.66 mg/L in the reservoir models and dissolved oxygen discrete sample concentrations in the Cedar River with an RMSE of 0.32-0.36 mg/L in the river models. Other water quality parameters were simulated within observed ranges for all parameters. Three climate change scenarios considered changes in meteorological data and inflow data. Two reservoir management scenarios considered changes in reservoir storage and spring refill level. The scenario with the greatest predicted impact was Scenario 1, in which air temperature and water temperature were increased by a uniform 3°C. Temperature change of the average monthly temperature at noon increased by 1.0-2.6°C across the watershed. Dissolved oxygen concentrations less than 6 mg/L were predicted 9 percent of the time for the reservoir from May to September compared to 0 percent in the base model and all other scenarios. Other water quality parameters did not experience significant change under any of the modeled scenarios. The impact on fish habitat under each scenario was determined for the reservoir model and the river model. Non-lethal growth conditions for bull trout in Scenario 1 decreased by 2 to 20 percent of reservoir volume from June through October. Core summer salmonid habitat decreased by 1 to 13 percent of river volume from mid June through mid September under Scenario 1. The calibrated Cedar River Municipal Watershed model provides a watershed management tool to help implement new management scenarios and prepare for the impacts of climate change. Current model limitations include a reliance on the historically observed Masonry Pool water levels to control outflows from the reservoir in management scenarios. Operation logic that de couples the model from the historically observed water surface elevations should be developed. This would allow the model to be a more useful management tool based on operation logic rather than observed operation strategy