An isotopic dilution method was used to test the effects of osmotic potential, (IJ' ,), upon nitrification, ammonification, N-immobilization, and nitrous oxide production rates in soil at solute concentrations encountered in Penoyer soil. A nitrification potential assay was also performed to approximate maximum nitrification rates. Nitrification potential rates in soil slurries exponentially declined in response to decreased osmotic potential. However, nitrification was independent of salt concentration at the ambient NIL+ concentrations of the soil. The differential response was attributed to the variable NIL+ substrate quantities. The effects of osmotic potential were secondary to NIL+ substrate levels in controlling nitrification rates. Ammonification rates declined exponentially as a function of decreased osmotic potential; however, the 33% reductions in ammonification rates were restricted to a range of osmotic potentials between 0 and -500 kPa. Ammonification rates were independent of osmotic potential at potentials between -500 and -1800 kPa. Immobilization rates of both NH/ and N03- declined exponentially as osmotic potential decreased. Absolute rates ofN03- immobilization exceeded those of N~ • by a factor of 4, indicating that under N~+ limited conditions, substantial N03- assimilation occurred. However, the generalization that N~ + is the preferred N source was in fact supported by the data, where immobilization rates relative to the respective pool sizes clearly favored NH4 + assimilation. Nitrous oxide production rates increased linearly as osmotic potential decreased. An NH4 + dependence indicated the evolved N20 was derived from nitrification rather than denitrification.

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第18859号 / 医博第3970号 / 新制||医||1008(附属図書館) / 31810 / 京都大学大学院医学研究科医学専攻 / (主査)教授 渡邊 直樹, 教授 渡邉 大, 教授 松原 和夫 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DGAM

京都大学 / 0048 / 新制・論文博士 / 博士(農学) / 乙第13215号 / 論農博第2864号 / 学位論文||H30||N5153(農学部図書室) / (主査)教授 川島 茂人, 教授 星野 敏, 教授 藤原 正幸 / 学位規則第4条第2項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

Food production security and resiliency require combination of agricultural management practices that are environmentally friendly and economically viable. Cover crops and tillage are two typical management practices that influence corn (Zea mays L.) and soybean (Glycine max L.) production in Illinois and the Midwest, USA. Finding practices that could potentially reduce nitrous oxide (N2O) emissions and sequester carbon (C) in the soil can improve agricultural resiliency to climate change. Generally, shifting from reduced tillage (RT) to no-till (NT) improves soil structure and decreases C emissions or sequesters soil C but might increase N2O emissions. Including a legume cover crop such as hairy vetch (Vicia villosa L.) before corn is preferred to winter cereal cover crops (WCCCs) to avoid yield penalty in corn and ensure high grain production. Winter cereal cover crops such as winter cereal rye (Secale cereale) (WCR) could potentially decrease soil N2O emissions during fallow period by capturing residual N and reducing soil moisture. These conditions could change in soils with legacy tillage (RT vs. NT) effects due to changes in soil physical, chemical, and biological over time. We utilized a medium-term (six-year-old) trial to test several hypotheses. We hypothesized that RT increases the soil temperature, accelerates soil organic matter mineralization, and especially in combination with hairy vetch could increase soil N in the soil leading to increased corn grain yield and N2O emission (Chapter 1). We also hypothesized that WCR takes up residual N after harvesting corn, decrease soil N, use soil moisture, and therefore, could decrease soil N2O emission (Chapter 2). For study 1 (Chapter 1), our objective was to evaluate the influence of cover crop (hairy vetch) vs. a no CC control and tillage systems (RT vs. NT) on (i) corn yield, N uptake, removal, and N balance; (ii) N2O emissions during corn season; (iii) yield scaled N2O emissions on a long-term (eight years) tillage × cover cropping system during the corn growing season in 2019 and 2021. We also analyzed factors that influence N2O emissions via principal component analysis in corn season. In corn growing seasons, we found that corn grain yield was higher in RT than NT reflecting on more N in the soil in RT than NT. Hairy vetch increased corn grain yield, soil N, and N2O-N indicating increased corn grain yield by hairy vetch N contribution let to higher N loss. Yield-scaled N2O-N emissions in NT-2019 (3696.4 g N2O-N Mg-1) were twofold higher than RT-2019 (1872.7 g N2O-N Mg-1) and almost fourfold higher than NT-2021 and RT-2021 indicating in a wet year like 2019, yield-scaled N2O-N emissions were higher in NT than RT. Principal component analysis indicated N2O-N fluxes were less driven by soil N and more by environmental conditions and N balances reflecting on N application at planting in this trial. . The objectives for chapter 2 were to evaluate the legacy effect of tillage (RT vs. NT) and cover crops (WCR vs. a no cover crop control) on soil nitrate-N (NO3-N), volumetric water content (VWC), temperature, and N2O emission trends during a fallow period after corn in a six-yr trial. In spring 2020 we also estimated WCR biomass and N uptake as affected by tillage practices and compared WCR biomass to weeds in the no cover crop treatment. In rye growing season, winter cereal rye biomass was 55% higher than weeds in the fallow treatment. A linear positive relation between WCR biomass and N uptake (R2= 0.93) and C accumulation (R2 = 0.99) indicates WCR captures more N and adds more C inputs than weeds. Winter cereal rye biomass was also higher in RT than NT reflecting on higher soil temperature and N availability in RT than NT. Soil VWC was lower in WCR plots and there was a negative linear relation between days of the year (DOY) and VWC (R2 = 0.6). Despite all these differences, soil N2O-N values were mainly less than 5 g N2O-N ha-1d-1 in all sampling dates regardless of tillage or cover crop treatment. We conclude that in poorly drained Alfisols with claypan and fragipans, NT is not an effective strategy to decrease N2O-N fluxes. Hairy vetch benefits corn grain yield and supplement N but that increases N loss through N2O-N emissions. We concluded that we should focus on decreasing N2O emissions early in corn season since majority of N is lost during that time sometimes 300 times higher than those reported during the WCR phase. Some changes in management practices that could reduce N2O losses are shifting from upfront N application to sidedress N management, terminating hairy vetch at or even after corn planting, and combine these efforts with enhanced efficiency fertilizers that control nitrification and denitrification.

The design, development, integration and testing of a full-featured, Lab-Scale Hybrid Rocket Engine was not only envisioned to be the chosen method of putting student payloads into space, but to be an invaluable teaching resource. The subject of the present thesis is the analysis, design, development, integration and demonstration of a lab-scale hybrid rocket motor. The overarching goal of this project was to establish a working developmental lab model from which further research can be accomplished. The lab model was specifically designed to use a fuel source that could be studied in normal laboratory conditions. As such, the rocket engine was designed to use Hydroxyl Terminated Polybutadiene as the fuel and Liquid Nitrous Oxide as the oxidizer. Developing the rocket engine required the usage of several electronics modules and a software package. The custom-designed electronics modules were a Signal Conditioning & Data Amplification Interface and a Data Acquisition Network. The software package was coded in Visual Basic (VB). A MathCAD regression rate computer model was designed and written to geometrically constrain the engine design. Further, the computer model allowed for the "what-if" situations to be evaluated. Using ProPep, solutions to the Equilibrium Thermodynamics Equations for the fuel and oxidizer mixture were obtained. The resultants were used as initial input to the computer model for predicting the lab-scale rocket's Chamber Pressure, Chamber Temperature, Ratio of Specific Heats and Molecular Weight. Details on the model, the rocket hardware, and the successful test firing are provided.

This doctoral research provides an advanced molecular approach for the investigation of microbial structure and function in response to operational conditions of biological nitrogen removal (BNR) processes, including those leading to direct production of a major greenhouse gas, nitrous oxide (N₂O). The wastewater treatment sector is estimated to account with 3% of total anthropogenic N₂O emissions. Nevertheless, the contribution from wastewater treatment plants (WWTPs) is considered underestimated due to several limitations on the estimation methodology approach suggested by the Intergovernmental Panel on Climate Change (IPCC). Although for the past years efforts have been made to characterize the production of N₂O from these systems, there are still several limitations on fundamental knowledge and operational applications. Those include lack of information of N₂O production pathways associated with control of aeration, supplemental organic carbon sources and adaptation of the microbial community to the repeated operational conditions, among others. The components of this thesis, lab-scale investigations and full-scale monitoring of N₂O production pathways and emissions in conjunction with meta-omics approach, have a combined role in addressing such limitations. Lab-scale experiments imposing short-term anoxic-aerobic cycling on partial- and full-nitrification based processes were conducted to investigate the microbial response to N₂O production. Interestingly, it was determined that full-nitrification systems could be a higher contributor to N₂O production and emissions than partial-nitrification. While it has been reported in the literature a higher contribution from the latter when the microbial community is not subjected to oxygen cycling conditions. Following the knowledge obtained with a single anoxic-aerobic cycle imposed to nitrifying communities, long-term adaptation of the microbial community to continued anoxic-aerobic cycling and its impact on N₂O production were investigated through a meta-omics approach. Long-term studies are particularly significant regarding engineered systems, where the microorganisms are continually subjected to cycling conditions again and again. A microbial adaptation at the RNA level was identified on both autotroph and heterotroph organisms. The transcripts of the metabolic pathways related to NO and N₂O production (nir, nor) and consumption (nor, nos) were initially induced followed by a gradual decline, leading to a parallel reduction in gaseous emissions over time. Other pathways not typically interrogated in conjunction with the nitrogen metabolism, such as electron transport chain and carbon fixation were also investigated and revealed a mechanism to overcome the imbalance in electron flow and generation of proton motive force (increased transcription of terminal oxidase genes, cco and cox) to uphold carbon fixation during continued cycling. The second part of this thesis focuses on full-scale WWTPs, where it is crucial to determine specific nuances of the systems’ dynamics and of the different types of treatment that may contribute to increased production and emissions of N₂O. For that purpose, two distinct BNR systems not usually considered and studied in terms of N₂O production and emissions were chosen. First, a separate centrate treatment (SCT) process employing glycerol as the supplemental carbon source was monitored. Significantly, this system was found to have one of the highest levels of N₂O production and emission report thus far. Glycerol revealed to foster a microbial community (i.e. Burkholderiales, Rhodobacterales and Sphingomonadales) that stores internal carbon and promote partial denitrification, leading to accumulation of nitrite and N₂O [7-11]. Second, both fixed- and moving-bed biofilm BNR systems were investigated. The overall N₂O emission fractions for the Integrated Fixed-Film Activated Sludge (IFAS)(0.09 – 1.1% infl-TKN) and denitrification filters (0.11 – 1.4% infl-TN) were similar to the reported emissions from suspended growth activated sludge systems [4-6]. For the IFAS system, aqueous and gaseous N₂O profiles paralleled the diurnal variability on influent nitrogen load. The production of N₂O was significantly correlated with ammonia concentration (p<0.05, r=0.91), suggesting the production through hydroxylamine oxidation pathway. Denitrification filters displayed a very peculiar pattern on N₂O emissions associated with intermittent operational cycles (i.e. nitrogen release cycle and backwash). These intrinsic operations of the denitrification filters contributed to transient oxygen conditions and nearly the entire N₂O emissions through gaseous stripping and production by inhibition of denitrification. Similarly to suspended growth systems, process design and operations demonstrated to also play an important role in N₂O emissions from attached growth processes. Finally, aeration strategies for energy efficient conventional nitrification based on the microbial community development and its associated performance was investigated in lab-scale. It was demonstrated that using the same air supply rate, continuous and intermittent aeration resulted in completely different microbial structure. Consequently, distinct kinetics and nitrification performance were observed. The aeration rate could be minimized (resulting in reduction in energy consumption) for high ammonia removal efficiency and lower N₂O emissions, as long as the process is designed accordingly to the microbial ecology developed in such conditions. In sum, the microbial structure, function and connection of metabolic pathways of complex engineered microbial communities as applicable to BNR systems and its operations were investigated in detail. From an engineering perspective, this dissertation provides an advancement on the molecular approach to characterize structure and function of microbial responses to engineered operations beyond the business-as-usual target genes, which can eventually result in better design and control of engineered BNR processes. This study offers more than an improved scientific understanding of the complex microbial environment and direct engineering applications. It connects sanitation with water quality and the greenhouse gas effect by prioritizing concurrent enhanced biological nitrogen removal and mitigation of N₂O production and emission. Ultimately the implications of the result presented herein can provide economical, environmental, health benefits for the society.

Master of Science / Department of Agronomy / Charles W. Rice / Agricultural lands receiving N inputs are considered the primary source of N2O, a potent greenhouse gas. N fertilizer management has shown variable effects on both N2O losses and corn grain yield. The objectives of this study were to assess the impact of N source and placement on N2O emissions, fertilizer-induced emission factor (FIEF), corn grain yield, yield-scaled N2O emissions (YSNE) and N fertilizer recovery efficiency (NFRE). The experiment was conducted from 2013 through 2014 at the Agronomy North Farm located at Kansas State University, Manhattan, KS. The soil was a moderately well-drained Kennebec silt loam. The treatments were broadcast urea (BC-Urea), broadcast urea ammonium nitrate (UAN) (BC-UAN), broadcast coated urea (BC-CU), surface-band UAN (SB-UAN), subsurface-band UAN (SSB-UAN), subsurface-band UAN + nitrification inhibitor (SSB-UAN+I) and a 0 N control. In 2013, SSB- UAN emitted significantly more N2O (2.4 kg N2O-N ha-1), whereas control (0.3 kg ha-1) and BC- UAN (0.6 kg ha-1) emitted the least. In 2014, most treatments emitted between 3.3 and 2.5 kg N2O-N ha-1. Only SSB-UAN+I (1.03 kg ha-1) and control (0.26 kg ha-1) were significantly lower. The use of a nitrification inhibitor decreased N2O emissions by 62% and 55% in 2013 and 2014, respectively. BC treatments had cumulative emissions significantly higher in 2014 compared to 2013. Only SSB-UAN+I had a significantly lower FIEF (0.4%), and 2013 FIEF (0.68%) was significantly lower than that of 2014 (1.38%). In 2013, banded treatments had significantly higher grain yields (from 9.1 to 10.5 Mg ha-1), whereas in 2014 fewer differences among N treatments were observed, ranging from 7.2 to 8.6 Mg ha-1. Banded treatments had significantly lower grain yields in 2014 compared to 2013. Only BC-UAN and SSB-UAN+I had significantly lower YSNE, and 2013 had lower YSNE than 2014. In 2013, SSB-UAN had the greatest NFRE, whereas BC treatments had the lowest. In 2014, N treatments did not differ in NFRE. SSB-UAN and SSB-UAN+I had significantly lower NFRE values in 2014 compared to 2013. Fertilizer source and placement have the potential to mitigate N2O emissions and promote high yields and NFRE in corn, however, the response is dependent on the rainfall pattern after fertilizer application. The option of banding UAN without any additive promoted higher N2O losses on a year when precipitation was well distributed, but also enhanced grain yield and NFRE. On the other hand, under the same precipitation conditions, broadcasting N fertilizer promoted lower N2O losses, grain yield and NFRE, but those were all improved in a wet year. Therefore, the subsurface band placement would be the best option under a normal year, whereas broadcasting fertilizer would be the best option under a wetter year. Further, the use of NI with subsurface band UAN provides the most sustainable option, since the NI decreased N2O losses compared to UAN alone in both years. Further research should evaluate N source and placement combinations under different environments in order to better understand how they impact crop performance and the negative environmental aspects of N fertilization. It is important to test those treatments under different precipitation scenarios and look for trends that indicate the best N management option at the local level.

Procedursmärta är den vanligaste orsaken till smärta hos barn i sjukvården. Dagligen genomförs diagnostiska och terapeutiska procedurer på barn, som både är skrämmande och smärtsamma. Barn som upplever otillräcklig smärtlindring under medicinska procedurer har en högre nivå av rädsla och ångest inför framtida procedurer, de reagerar dessutom kraftigare på akut smärta. Att låta barn inhalera en blandning av lustgas och syrgas ger både en smärtlindring och sedering. Stor fördel är att lustgas är enkel att administrera, har en kort anslagstid och effekten avklingar snabbt när inhalationen avslutas, och ger få biverkningar. Syftet med litteraturstudien var att beskriva effekten av lustgas i samband med att barn utsätts för smärtsamma procedurer inom hälso- och sjukvården. En litteraturstudie utfördes där tio vetenskapliga studier grundlade resultetet. Vid bearbetningen identifierades tre olika teman, dessa var; Lustgas och smärta, Lustgas och biverkningar, Lustgas och fasta. I resultatet framkom att lustgassedering är en effektiv och säker metod för att uppnå smärtlindring och sedering under mindre, men smärtsamma medicinska procedurer, med få biverkningar. Allt fler barn sederas med lustgas vid olika medicinska procedurer av icke anestesiutbildade sjuksköterskor. En konklusion av resultatet var, för att sjuksköterskan ska kunna möta kraven måste systematisk utbildning och träning finnas och tydliga guidelines utarbetas och vara förankrad hos all personal. Detta måste prioriteras, förbättras och kontinuerligt uppdateras.

Nitrous oxide (N2O) is a widely used anesthetic adjunct in dentistry and medicine that is also commonly abused. N2O alters the function of several receptors in vitro and ex vivo, however, the receptors systems underlying its abuse-related intoxicating effects are poorly understood. The goals of this dissertation were to (1) establish N2O as a discriminative stimulus, (2) characterize the temporal properties of the discriminative stimulus, (3) determine the degree of similarity between N2O and other inhalants and (4) explore the neurochemical effects responsible for the stimulus properties of N2O. Twenty-four mice were trained to discriminate 10 minutes exposure to 60% N2O+40% O2 from 100% O2 in daily 5 minute food-reinforced operant sessions. Mice acquired the discrimination in a mean of 38 sessions. N2O produced concentration-dependent full substitution for itself. Full substitution required 7 minutes of N2O exposure but the offset of stimulus effects following cessation of N2O exposure were more rapid. Varying degrees of partial substitution for N2O were engendered by abused vapors and vapor anesthetics. The aromatic hydrocarbon toluene produced the most robust substitution for N2O. One or more toluene concentrations produced full substitution for N2O in 7 of 8 subjects, suggesting that these two abused inhalants share common neurochemical mechanisms. The NMDA receptor open channel blockers (+)-MK-801, ketamine and memantine produced dose-dependent partial substitution for N2O. A competitive NMDA antagonist and NMDA glycine site antagonist did not substitute for N2O. Pretreatment with (+)-MK-801 as well as ethanol produced dose-dependent leftward shifts in the N2O concentration effect curve further suggesting some overlap in their mechanisms of action. GABAA agonists and positive allosteric modulators, opioid agonists, serotonergic agonists, nicotine, a nNOS inhibitor and the psychomotor stimulant amphetamine all failed to appreciably substitute for N2O and/or failed to alter the N2O concentration effect curve when administered prior to N2O exposure. No drug tested produced greater than 80% mean N2O-lever selection leaving open the possibility of other neurochemical contributors to the stimulus effects of N2O.

Doctor of Philosophy / Department of Agronomy / Charles W. Rice / Nitrogen is critical for plant growth and is a major cost of inputs in production agriculture. Too much nitrogen (N) is also an environmental concern. Agricultural soils account for 85% of anthropogenic N₂O which is a major greenhouse gas. Management strategies for N fertilization and tillage are necessary for enhancing N use efficiency and reducing negative impacts of N to the environment. The different management practices induce changes in substrate availability for microbial activity that may result in increasing or reducing net N₂O emitted from soils. The objectives of this research were to (1) integrate results from field studies to evaluate the effect of different management strategies on N₂O emissions using a meta-analysis, (2) quantify N₂O-N emissions under no-tillage (NT) and tilled (T) agricultural systems and the effect of different N source and placements, (3) perform sensitivity analysis, calibration and validation of the Denitrification Decomposition (DNDC) model for N₂O emissions, and (4) analyze future scenarios of precipitation and temperature to evaluate the potential effects of climate change on N₂O emissions from agro-ecosystems in Kansas. Based on the meta-analysis there was no significant effect of broadcast and banded N placement. Synthetic N fertilizer usually had higher N₂O emission than organic N fertilizer. Crops with high N inputs as well as clay soils had higher N₂O fluxes. No-till and conventional till did not have significant differences regarding N₂O emissions. In the field study, N₂O-N emissions were not significantly different between tillage systems and N source. The banded N application generally had higher emissions than broadcasted N. Slow release N fertilizer as well as split N applications reduced N₂O flux without affecting yield. Simulations of N₂O emissions were more sensitive to changes in soil parameters such as pH, soil organic carbon (SOC), field capacity (FIELD) and bulk density (BD), with pH and SOC as the most sensitive parameters. The N₂O simulations performed using Denitrification Decomposition model on till (Urea) had higher model efficiency followed by no-till (compost), no-till (urea) and till (compost). At the regional level, changes in climate (precipitation and temperature) increased N₂O emission from agricultural soils in Kansas. The conversion from T to NT reduced N₂O emissions in crops under present conditions as well as under future climatic conditions.