Groundwater is a valuable source of drinking water and projects that manages groundwaterneed to prevent complications on the water’s characteristics. In an infrastructural project,groundwater reduced from elevated levels of nitrate needed to be recharged into the aquifer inthe area. This study aimed to describe important parameters to consider while performingartificial recharge. To fulfil the aim four research questions were answered; 1) What are thesurficial deposits in the area and how do they affect infiltration? 2) Are there any geologicalstructures that can influence the flow pattern due to infiltration? 3) What is the flow directionpattern in the area and how does it affect infiltration? 4) How does the infiltration attemptinfluence the groundwater levels and flow pattern in the aquifer? Previous literatures werestudied to find parameters that could affect the choice of location for an infiltration attempt.These parameters were used in Pugh’s concept selection and the most suitable location wasfound. To evaluate the attempt the groundwater levels were measured before and afterinfiltration to locate any local rise in groundwater levels. The results showed no rise ingroundwater levels that would change the flow pattern in the area and the location proved tobe suitable for infiltration in the future. The surficial deposits, groundwater flow direction andthe bedrock topology in the area proved to be important parameters that limited the possiblelocations for groundwater recharge. Future studies need to include these parameters and takeeconomic factors and land use into account to find appropriate infiltration locations.

A novel strategy for site-specific DNA transformation of plants has been proposed and the first component of the system developed. The proposed method overcomes the limitations of current techniques by providing a specific integration site for the insertion of transgenes using features of the adeno-associated virus (AAV) life cycle. In the absence of helper virus, AAV integrates into a specific location on human chromosome 19, the AAVS1 locus. The sequence for AAV integration was introduced into the model plant Arabidopsis thaliana using Agrobacterium tumefaciens-mediated transformation. A portion of the human AAVS1 sequence, including the Rep binding site (RBS) and terminal resolution site (TRS), was cloned between T-DNA borders of the Agrobacterium Ti plasmid. The reporter gene, b-glucuronidase (GUS) was inserted proximal to AAVS1 in the plasmid for use in screening for the presence of T-DNA. In addition, it will serve as an indicator of the expression level expected for transgene inserted into AAVS1 by recombinant AAV. PCR amplification, dideoxy sequencing, GUS expression assays and genomic Southern blots were performed to examine putative transgenic plants for the presence of the AAVS1 sequence. / Master of Science

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No description available.

Yes / While achieving the spatial organization of cells within 3D assembled nanofiber/cell constructs via nanofiber-enabled cell layering, the small sizes of inter-fiber pores of the electrospun nanofiber mats could significantly limit cell penetration across the layers for rapid formation of an integrated tissue construct. To address this challenge, efforts were made to improve cell-infiltration of electrospun nanofiber mats by modulating the density distribution and spatial organization of the fibers during electrospinning. Collection of collagen-containing electrospun nanofibers (300–600 nm in diameter) onto the surface of a stainless steel metal mesh (1 mm × 1 mm in mesh size) led to the periodic alternation of fiber density from densely packed to loosely arranged distribution within the same mat, in which the densely packed fibers maintained the structural integrity while the region of loose fibers allowed for cell penetration. Along with improved cell infiltration, the distinct fiber organization between dense and loose fiber regions also induced different morphology of fibroblasts (stellate vs. elongated spindle-like). Assembly of cell-seeded nanofiber sheets into 3D constructs with such periodically organized nanofiber mats further demonstrated their advantages in improving cell penetration across layers in comparison to either random or aligned nanofiber mats. Taken together, modulation of nanofiber density to enlarge the pore size is effective to improve cell infiltration through electrospun mats for better tissue formation. / NSF-IIP. Grant Numbers: 1338958, 1346430; NSF-DMR. Grant Number: 1508511; NSF-CBET. Grant Number: 1033742; and NIAMS. Grant Number: 1R21 AR056416

The Mekong River Basin (MRB) is one of the largest transboundary basins in the world shared between six south Asian countries. The Mekong river supports a population of more than sixty million people through irrigation and fisheries for their survival and hosts approximately 88,000 MW of unharnessed hydropower potential. The construction of the dams for the supply of energy has a wide-ranging effect on the downstream regions of reservoirs, causing unprecedented and devastating damage to the environment and livelihood of people. The dissertation examines the optimal operation of the dams for the equitable distribution of water between irrigation, domestic, and hydropower sectors with minimal effect on the downstream ecosystem by estimating the cascading effects of dams in the MRB. The hydrological characteristic of the MRB was simulated using the high resolution (1 km) Variable Infiltration Capacity (VIC) hydrological model with the Lohmann et al. (1996, 1998) routing scheme and general circulation models projection for the future till 2099. Remote sensing products were used for the derivation of the reservoir behaviors, while the net irrigation water requirement (NIWR) was simulated by the irrigation scheme embedded in the improved VIC model. The VIC-MODFLOW (VIC-MF) coupled model was used for the investigation of the interaction between the surface and groundwater movement. The hydropower potential of the dams was estimated using the modified Hanasaki et al. (2006) approach by explicitly considering the irrigation water demand from the expanding and intensifying agricultural activities. A system dynamic model for the MRB was developed for the sustainable optimization of water allocation to meet the needs from the irrigation, domestic, hydropower generation, and ecological sectors. Economic analysis was performed to evaluate the existing and future conditions over the resource surplus regions with consideration of social impacts. Streamflows in the MRB varied substantially with the peak monthly streamflow from 10 m3/sec to 40,000 m3/sec. The inflows to dams in both main river and tributaries are projected to increase from 1.2% to 25% under RCP 4.5 and a decrease of 28.5% - 74.7% under RCP 8.5 during 2020-2099 as compared to the historic mean. The NIWR for the MRB was calculated as 65,000 million m3 for the observed period (1981-2019) with a decrease of 0.25% for the future period. The groundwater interaction is expected to enhance the surface streamflow resulting in additional inflow to dams. The multipurpose reservoirs were able to generate the desired annual energy ranging from 15 GWh to 400 GWh along with satisfying more than 80% of the irrigation water demand. Similarly, the irrigation reservoirs also satisfied more than 80% of the water demand for irrigation and hydropower reservoirs to generate the required energy between 2 GWh and 18990 GWh. Climate change will enhance the hydropower potential with an average increase of 7.3% and 5.3% in the future under RCP 4.5 and RCP 8.5, respectively. The increase in the irrigated area (5% and 10%) reduces the energy generation of the multipurpose dams by 1.5%, however, the addition of a crop cycle lowers the energy generation by more than 10%. The system dynamics model showed the multipurpose dams produced annual energy of 316 GWh and satisfied more than 60% of the irrigation, municipal, and industrial sectors water demand during 2006-2019. Similarly, irrigation dams supplying more than 60% of the irrigation water demand, and 50% of the municipal and industrial sectors demand. Climate change has a positive influence on the performance of the dams. The assessment of the shadow price shows that the dam operation in Thailand, Laos PDR, and China will be sufficient to meet the water demands of the energy, irrigation, municipal, and industrial sectors, while the energy sector of Cambodia and Vietnam may experience adverse impacts. / Doctor of Philosophy / The Mekong River Basin (MRB) is one of the largest transboundary basins in the world shared between six south Asian countries. The Mekong river supports more than sixty million people through irrigation and fisheries for their survival and hosts unharnessed hydropower potential. The construction of the dams has a wide-ranging effect on the downstream regions of reservoirs, causing damage to the environment and livelihood of people. The dissertation studies the optimal operation of the dams in the MRB for the equitable distribution of water between irrigation, domestic, and hydropower sectors with minimal effect on the ecosystem. The streamflow of the MRB was simulated using the hydrological model with a routing scheme and future projection till 2099. Remote sensing products were used for the derivation of the reservoir behaviors. The water requirement for the irrigation and the groundwater-surface interaction was simulated by the irrigation scheme embedded in the hydrological model and groundwater coupled model. The hydropower potential of the dams was estimated by explicitly considering the irrigation water demand from the expanding and intensifying agricultural activities. A dynamic model for the MRB was developed for the sustainable optimization of water allocation to meet the needs from the irrigation, domestic, hydropower generation, and ecological sectors. Economic analysis was performed to evaluate the existing and future conditions over the resource surplus regions with consideration of social impacts. Streamflows in the MRB varied substantially between the dams based on the location at the mainstem or tributaries. The inflows to dams in both main river and tributaries in the future is expected to increase under low-carbon emission and decrease under high-carbon emission conditions. The irrigation water for the MRB was calculated as 65,000 million m3 for the period 1981-2019 and expected to decrease in the future. The groundwater interaction is expected to increase the surface streamflow resulting in additional inflow to dams. The multipurpose reservoirs were able to generate the desired annual energy ranging along with satisfying more than 80% of the irrigation water demand. Similarly, the irrigation reservoirs also satisfied more than 80% of the water demand for irrigation and hydropower reservoirs to generate the required energy. Climate change will favor the hydropower energy potential in the future. The increase in the irrigated area and the addition of a crop cycle reduces the energy generation of the multipurpose dams. The system dynamics model showed the multipurpose dams produced 97% of the demand energy and satisfied more than 60% of the irrigation, municipal, and industrial sectors water demand during 2006-2019. Similarly, irrigation dams supplying more than 60% of the irrigation water demand, and 50% of the municipal and industrial sectors demand. Climate change has a positive influence on the performance of the dams. The assessment of the shadow price shows that the dam operation in Thailand, Laos PDR, and China will be sufficient to meet the water demands of the energy, irrigation, municipal, and industrial sectors, while the energy sector of Cambodia and Vietnam may experience adverse impacts.

Increases in impervious surfaces associated with urbanization change stream hydrology by increasing peak flow rates, storm-flow volumes and flood frequency, and degrade water quality through increases in sediment, nutrient, and bacteria concentrations. In response to water quality and quantity issues within the Stroubles Creek watershed, the Town of Blacksburg and Virginia Tech designed and constructed two innovative stormwater best management practices (BMPs). The goal of this project was to evaluate the effectiveness of a bioretention cell and a CU-Structural Soil™ infiltration trench. BMP construction was completed in July 2007. Twenty-nine precipitation events were monitored over a period of five months between October 2007 and March 2008. For each storm, inflow and outflow composite samples were collected for each BMP and analyzed for suspended sediment, total nitrogen, total phosphorus, fecal coliform bacteria and E-coli bacteria. The inflow and outflow concentrations and loads, as well as total inflow and outflow volumes and peak flow rates, were then compared to evaluate how well each BMP reduces stormwater flows, decrease peak runoff rates and improves water quality of stormwater runoff. Results for the bioretention cell indicate average reductions in stormwater quantity, sediment, total nitrogen, total phosphorus and fecal coliform bacteria that exceeded 99% by mass. The CU-Structural Soil™ infiltration trench produced reductions in stormwater quantity, total phosphorus and sediment that averaged 60%, 45% and 51%, respectively. Preliminary bacteria results indicated that both BMPs served as sources of E-coli, and the infiltration trench served as a source of fecal coliform bacteria. / Master of Science

Nous étudions la propagation et la quantification d'incertitudes paramétriques au travers de modèles hydrologiques pour la simulation des processus d'infiltration et d'érosion en présence de pluie et/ou de ruissellement. Les paramètres incertains sont décrits dans un cadre probabiliste comme des variables aléatoires indépendantes dont la fonction de densité de probabilité est connue. Cette modélisation probabiliste s'appuie sur une revue bibliographique permettant de cerner les plages de variations des paramètres. L'analyse statistique se fait par échantillonage Monte Carlo et par développements en polynômes de chaos. Nos travaux ont pour but de quantifier les incertitudes sur les principales sorties du modèle et de hiérarchiser l'influence des paramètres d'entrée sur la variabilité de ces sorties par une analyse de sensibilité globale. La première application concerne les effets de la variabilité et de la spatialisation de la conductivité hydraulique à saturation du sol dans le modèle d'infiltration de Green--Ampt pour diverses échelles spatiales et temporelles. Notre principale conclusion concerne l'importance de l'état de saturation du sol. La deuxième application porte sur le modèle d'érosion de Hairsine--Rose. Une des conclusions est que les interactions paramétriques sont peu significatives dans le modèle de détachement par la pluie mais s'avèrent importantes dans le modèle de détachement par le ruissellement / We study parametric uncertainty propagation and quantification in hydrological models for the simulation of infiltration and erosion processes in the presence of rainfall and/or runoff. Uncertain input parameters are treated in a probabilistic framework, considering them as independent random variables defined by a fixed probability density function. This probabilistic modeling is based on a literature review to identify the range of variation of input parameters. The output statistical analysis is realized by Monte Carlo sampling and by polynomial chaos expansions. Our analysis aims at quantifying uncertainties in model outputs and establishing a hierarchy within input parameters according to their influence on output variability by means of global sensitivity analysis. The first application concerns the variability and spatial localization of the soil saturated hydraulic conductivity in the Green-Ampt infiltration model at different spatial and temporal scales. Our main conclusion is the importance of the soil saturation state. The second application deals with the Harisine--Rose erosion model. One conclusion is that the parametric interactions are not significant in the rainfall detachment model, but they prove to be important in the runoff detachment model

Gävle kommuns VA-huvudman Gästrike Vatten AB ansvarar för dricksvattenproduktionen i Gävle. För Gävles tätort tas vatten från Valboåsen som sträcker sig från öster om staden, genom staden och vidare norrut. Denna rapports syfte är att genom mätning av halten löst syre undersöka Valboåsens förbindelse till Gavleån. Detta kommer ge en ökad förståelse för åsens komplexitet. Resultatet kommer också att användas för att verifiera och utveckla den konceptuella modellen över flödena i åsens grundvattenmagasin som tagits fram av Midvatten AB. För att kunna mäta halten löst syre har en provtagning skett på grundvattenrör. I provtagningen ingick även så kallade slugtest där rörens kapacitet och anslutning till grundvattenmagasinet säkerställdes. Efter mätningen sammanställdes resultatet för att kunna jämföra halten löst syre i grundvattenrören mot den konceptuella modellen. Resultatet visade att halten löst syre i vattnet i de olika grundvattenrören stöder den konceptuella modellen till stora delar och gav även mer information om områden längs åsen där kunskap om flödesförhållandena tidigare var osäkra. Metoden i den utförda studien har visat stor användbarhet för att påvisa flödesförhållanden och ytvattenpåverkan i Valboåsen vilket visar att mätning av syrehalt kan vara mycket användbart i grundvattenutredningar angående ytvattenpåverkan. För att utöka studien av Valboåsen i framtiden behövs mer provtagning i grundvattenmagasinet på områden som inte ingick i denna studie. / Gävle municipality's water company is Gästrike Vatten AB. They manages the drinking water production for the City of Gävle. The production starts in the ridge of Valbo which extends between Överhärde (located in the south part of Valbo) and Strömsbro (located in the north part of Gavle). Purpose of this report is to measure the dissolved oxygen content in the aquifer throughout the whole area to investigate where the infiltration from the nearby Gavle River occurs. The aim of the study is to get a better understanding of the complexity of the Valbo ridge. The measurements will help to verify or modify the conceptual model of the directions of water flow in the Valbo ridge, developed by Midvatten AB. Dissolved oxygen content was measured through ground water pipes. To assess the pipes’ capacity and connection to the aquifer, slug tests were performed. The dissolved oxygen data were analyzed and compared with the conceptual model. The results showed that the dissolved oxygen content in the water supported the conceptual model to a large extent and also gave previously unknown information on some stretches of the ridge. The method shows great potential for additional future studies in Valbo ridge and elsewhere. To expand the study further, a need for more sampling of the aquifer throughout the areas that were not included in this study.

Dans un contexte de développement du trafic aérien, et en vue de répondre aux nouvelles normes environnementales, il est désormais impératif de diminuer la consommation de carburant et les émissions de gaz des moteurs, ainsi que d’en améliorer le rendement. Pour ce faire, la conception des dispositifs, mais aussi leur fabrication et les matériaux employés sont repensés.Plus légers, inertes chimiquement et capables de conserver leurs propriétés mécaniques même à haute température, les matériaux composites à matrice céramique SiC/SiC sont des matériaux prometteurs pour remplacer certaines pièces métalliques des moteurs aéronautiques et atteindre cet objectif. Une des voies prometteuses d’élaboration de ces composites est l’imprégnation de silicium liquide (Melt Infiltration, dite MI) dans une préforme de fibres de carbure de silicium, revêtues de SiC (SiCCVI), préalablement imprégnée de poudre de SiC (SiCp).Le silicium doit remplir les pores de la préforme sans dégrader ses constituants. Néanmoins, des interactions locales entre le silicium liquide (SiL) et le revêtement en carbure de silicium (SiCCVI) des fibres de SiC ont été mises en évidence. Elles se traduisent par une dégradation du revêtement pouvant aller jusqu’à la destruction des fibres. Le premier objectif de cette thèse est donc de comprendre ces interactions SiL- SiCCVI et d’identifier les principaux facteurs. Par la suite, la modulation des interactions SiL- SiCCVI peut être envisagée par l’ajout de poudre de SiCp ainsi que par l’utilisation de l’alliage Si-B. L’objectif de ce second volet de la thèse sera de comprendre comment la (les) poudre(s) et l’alliage Si-B influent sur les interactions (paramètres et mécanismes). / Increase of the air traffic and recent environmental standards require the reduction of the energy consumption and gas emission of the new aircraft engines. For this purpose, new materials have been developed.Lighter, chemically inert and suitable for high temperature applications, the Ceramic Matrix Composites SiC/SiC are promising materials for replacing some of the metallic turbine engine pieces and improving energy efficiency.From now on, CMC matrix was mainly elaborated by Ceramic Chemical Vapor Infiltration (CVI). However, this process is slow and costly, and the residual porosity is high. Then, the infiltration of liquid silicon (Melt Infiltration) in a SiC fibrous preform, coated with SiC (SiCCVI), and densified by SiC powders (SiCp) is an alternative route to full CVI.Even if liquid silicon (SiL) should fill the pores of the preform without reacting with SiC, local interactions have been noticed between the liquid silicon and the Sic deposit, which is deleterious to the final material mechanical properties. Therefore, this thesis aims at understanding the interactions SiL- SiCCVI and identifying the main parameters. This requires beforehand to characterize deeply and precisely the microstructure of the SiCCVI. Thereafter, research will focus on the control of the SiL- SiCCVI interactions.