京都大学 / 新制・課程博士 / 博士(工学) / 甲第24601号 / 工博第5107号 / 新制||工||1977(附属図書館) / 京都大学大学院工学研究科都市環境工学専攻 / (主査)教授 伊藤 禎彦, 准教授 西村 文武, 教授 越後 信哉 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

No description available.

No description available.

We analyze a toy model for p-n junction photovoltaic devices by simulating photoexcited state dynamics in silicon nanowires. One nanowire is approximately circular in cross section with a diameter of d = 1.17 nm. The other has an approximately rhombic cross-section with d1 = 1.16 nm and d2 = 1.71 nm. Both nanowires have been doped with aluminum and phosphorus atoms and capped with gold leads. We use Boltzmann transport equation (BE) that includes phonon emission, carrier multiplication (CM), and exciton transfer. BE rates are computed using non-equilibrium finite-temperature many-body perturbation theory (MBPT) based on Density Functional Theory (DFT) simulations, including excitonic effects from Bethe-Salpeter Equation. We compute total charge transfer amount generated from the initial photoexcitation and find an enhancement when CM is included. In particular, we see between 78% and 79% enhancement in the smaller wire, while we see 116% enhancement in the larger nanowire

Manure nitrogen in dairy cattle represents a substantial economic and environmental loss to the industry. Current strategies used to improve N efficiency (Neff) have shown limited progress and thus, warrant more effective approaches. Considering that the gastrointestinal bacterial community has been associated with various phenotypes of economic importance, the objective of this project was to evaluate the associations between the rumen and fecal bacteriomes and Neff phenotypes in dairy cows. Results showed similarities in the overall bacterial community composition and structure of cows differing in Neff. However, the relative abundance of specific bacterial ASV differed between low and high Neff cows. Furthermore, bacterial ASV strongly correlated with Neff could be involved in processes such as nutrient supply, performance, and feed efficiency. These suggest that the gastrointestinal bacterial community is a factor influencing Neff in dairy cows and specific bacterial members can potentially serve as markers of Neff phenotypes.

Note:

Nitrated polycyclic aromatic hydrocarbons (nitro-PAH) are environmental contaminants that have been identified in extracts of particulates obtained from automobile exhaust, diesel exhaust, and power plant emissions. One of the most abundant nitro-PAH, 1-nitropyrene, has been found to be a powerful bacterial mutagen and a carcinogen in animal tests. In a bacterial strain (Salmonella tvphimurium TA98) 1- nitropyrene undergoes reduction and concomitant covalent binding to DNA, presumably via the N-hydroxy-l-aminopyrene. This labile compound was prepared by the ascorbic acid reduction of 1-nitrosopyrene and was characterized by high performance liquid chromatography (HPLC), combined liquid chromatography-mass spectrometry (LC-MS), ultraviolet-visible (UV-VIS), fluorescence and nuclear magnetic resonance (NMR) spectroscopy (1H and 15N) . In addition the pH stability and some reactions of this compound were studied. The 1,6- and 1,8-hydroxylaminonitropyrenes derived from the very potent mutagens 1,6- and 1,8 dinitropyrene were also synthesized and characterized by high performance liquid chromatography, ultraviolet-visible and nuclear magnetic resonance spectroscopy (1H and 15N) . / Thesis / Master of Science (MSc)

No description available.

No description available.

Long-term watershed and field nitrogen (N) balances were used in this study to quantify the surface (baseflow) and ground water lag times and effects of BMPs on N discharge from a Virginia Coastal Plain watershed. Ten-year water quantity/quality data (1986-1996) collected at the Nomini Creek (NC) watershed were used. Field (Field-N) and watershed (Watershed-N) scale N models were developed for computing the N balances. BMPs evaluated in this study included no-till corn and split N application. The role of atmospheric N (atm-N) deposition (dry+wet) in masking the effects of BMPs on watershed N loading was also investigated. Nitrogen retention and discharge from the forest areas in the NC watershed were simulated using the 5-year water and N input and output data from forested subwatersheds. Field and watershed N balances (WNBAL) were used to evaluate the effects of BMPs on measured surface and ground water N in the NC watershed. A 6-month laboratory study was conducted to develop N mineralization (Nmin) models for agricultural, forest, and fallow soils in the NC watershed. Mineralization potential (N0) and rate constants (k) for surface and subsurface soils from agricultural, forest, and fallow soils were estimated by fitting the laboratory measured data to a first-order model, using the nonlinear regression procedure. A large variability (300%, 163 - 471 kg/ha) in N0 of agricultural surface soils was observed. On average, forest soils had much higher potentially mineralizable N than agricultural soils. The first-order model was incorporated into the Field-N model to predict daily Nmin using the measured N0 and k and daily values of soil water and temperature. Atmospheric deposition was a major source of N in the NC watershed, accounting for 23% of the total N input. Variation in atm-N deposition during the 10-year period was from 10 to 42 kg/ha (average = 25 kg/ha); much larger than the variation in fertilizer N (37 to 51 kg/ha). Atm-N deposition was found to be a controlling factor affecting surface water DIN (dissolved inorganic N) and TDN (total dissolved N) loading in the NC watershed; an indication that atm-N deposition is a masking factor in the BMP impact evaluation. Large uncertainty in atm-N deposition existed due to uncertainty involved in quantifying dry N deposition. Forested areas of the NC watershed retained 77% of the atm-N deposition. Forest area N discharge was simulated using the 77% retention and annual atmospheric deposition. Comparison of Field-N predicted N balance and leaching (steady-state and transient conditions) with observed ground water NO3 concentration revealed that the ground water lag time ranged from 2 to 8 months. Unusually rapid transport of solute in the watershed was facilitated by the network of discontinuous clay lenses. Based on the lag time, the pre-BMP (1986-1990) and post-BMP (1991-1995) periods were defined. Results from Field-N indicated that implementation of split fertilizer N on corn reduced the post-BMP ground water NO3 concentration by 10-12% at two of the four ground water monitoring sites. The split N application reduced the frequency of detection of high NO3 (> 9 mg/l) concentration by 44% during the post-BMP period. Considerably large uncertainty existed in evaluating the effects of BMPs on ground water NO3 due to N contributions from neighboring agricultural and forest areas. Effects of no-till corn could not be evaluated since this BMP was already implemented at the sites prior to the beginning of the study. Results of statistical trend analysis of the ground water N supported the modeling results. Watershed-N model was able to accurately predict the effects of land use activities on watershed N balances (WNBAL) and baseflow and ground water N. A one-to-one relationship between the WNBAL and observed N loading and concentration time series was observed. Comparison of WNBAL and measured baseflow N revealed that the baseflow lag time or residence time was between 4-11 months. Multivariate regression models were developed to predict baseflow N using Watershed-N results. The multivariate model predicted the N loading and concentration exceptionally well (R2 > 90%). Corn N input and output and acreage was an important predictor of ground water N and baseflow N loading and concentration. Post-BMP WNBAL was considerably less than the WNBAL for the pre-BMP period. However, these reductions were mainly due to the 43% reductions in atm-N deposition and 31% increase in the plant uptake during the post-BMP period. Reductions in WNBAL caused by BMPs were only 5%. Reductions in N loading caused by BMPs were 10%. Statistical trend analysis of monitoring and modeling results indicated significant post-BMP reductions in WNBAL and DIN and TDN loading. However, poor to moderate evidence was available to suggest that BMPs caused a significant reductions in WNBAL and N loading. Marginal effects of BMPs could mainly be attributed to insufficient BMP implementation. Watershed-N was used to evaluate N reduction scenarios and to design BMPs. Irrigating corn was one of the best BMPs, as it could reduce N loading from NC watershed by 50%. Quantification of lag time and long-term watershed N balances from this study provide crucial information for understanding N cycling and factors controlling N discharges which is essential for designing programs for controlling N discharges from Mid-Atlantic Coastal Plain watersheds. / Ph. D.