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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Development of an Analytical Method for Distinguishing Ammonium Bicarbonate from the Products of an Aqueous Ammonia Co2 Scrubber and the Characterization of Ammonium Bicarbonate

Meng, Lingyu 01 January 2004 (has links)
The link between anthropogenic emissions of CO2 with increased atmospheric CO2 levels and, in turn, with increased global temperature has been well established and accepted. Using aqueous ammonia to capture CO2 and produce an inexpensive nitrogen fertilizer, ammonium bicarbonate (ABC) has been thought as a feasible approach to CO2 sequestration. Due to the different concentrations of reactants and reaction conditions, different carbon-ammonium composites can be produced. In view of achieving a maximum of NH3 utilization in the capture of CO2, the product of ABC will be ideal. Hence the ABC in the products needs to be identified. Various analytical techniques were used to distinguish the ABC. FTIR, DSC, TGA and XRD techniques were used to qualitatively distinguish the ammonium bicarbonate from the ammonium salts. The carbon, hydrogen and nitrogen element analysis and Near Infrared (NIR) techniques were used as quantitative analysis of ABC. The AOTF-NIR Free Space spectrometer is an ideal tool for real-time, on-line measurements of ABC. Sample 01050401 and Sample 01060401 from the CO2 Scrubbing experiment by aqueous ammonia at WKU were determined by these techniques as ammonium bicarbonate and have very good quality as fertilizer in accordance with GB -3559-92 Agriculture Ammonium Bicarbonate National Standard of China. During fertilizer storage and application, an amount of ABC will decompose into NH3, H2O and CO2. Long-effect ABC (LEABC) is a product of co-crystallized dicyanodiamide (DCD) and ABC. In order to evaluate ABC fertilizer efficiency and its contribution to permanent carbon fixation, tests with Thermogravimetric Analysis (TGA) were conducted. The experiments by TGA indicated that the temperature and air flow rate have much less effect on the evaporation of the LEABC than on the ABC. Kinetic studies of ABC and LEABC gave their Activation Energy. At the 7.5% conversion rate, LEABC’s Activation Energy is 111.9 kJ/mole, which is greater than ABC’s Activation Energy 93.6 kJ/mole. The difference in Activation Energy explains the reason of different stability of ABC and LEABC.
2

The Reliability Of An Energy Balance Model In Simulating Climatic Responses Due To Increases In Carbon Dioxide Levels

Culver, Christopher Robin 04 1900 (has links)
<p> A relatively simple climatic model based on the energy balance has been used to examine the climatic responses due to increases in carbon dioxide CO2. Simulations concerning the CO2 concentration, the cloud fraction and the ocean's mixed-layer depth were all performed using an IBM-PC personal computer. The results were intended to provide a better understanding of the processes involved in an EBM, as well as the importance of this type of model in simulating climatic responses. There were four main areas of study within the research centred around both a decrease and an increase in CO2 concentration, changes in the cloud fraction and the influence of the ocean's mixed-layer. </p> <p> The role of the oceans in the climate system is still somewhat of a mystery to most scientists. in terms of its affect on a CO2 enhanced climate. Changes in the cloud fraction serve either to enhance or suppress the effect of CO2 on the surface temperature of the planet. This is dependant on whether the amount of cloud is reduced or increased. The focus of the study is based on the changes in carbon dioxide concentration levels. Simulations confirm, that when CO2 is reduced. the surface temperature will decrease as well. When CO is halved. the temperature decrease is 2.51 ° C. In contrast, when CO2 is doubled the surface temperature rose by 2.91 °C . Thus. causing the present clay climate of the model to warm drastically. </p> <p> The reliability of the results proved to be difficult to assess. The model tends to overestimate decreases in temperature when co~ is reduced in content. However. Burt's model does seem to accurately represent increases in temperature for 2x CO2 .The simulation results fall within a range defined by the results of selected radiative convective models (RCM). Nevertheless. there is a need for increased research in the area of effects. produced by other parameters on a CO2 enhanced climate. </p> / Thesis / Bachelor of Arts (BA)
3

Morphological and physiological studies of the carbon concentrating mechanism in Chlamydomonas reinhardtii

Chan, Kher Xing January 2019 (has links)
Chlamydomonas reinhardtii possesses a single-cell-based CO2-concentrating mechanism (CCM). The CCM is an important element of algal photosynthesis, metabolism, growth and biomass production, which works by increasing the concentration of inorganic carbon (Ci) in the pyrenoid, a dense RuBisCO-packed structure within the chloroplast. This suppresses RuBisCO oxygenase activity and associated photorespiration. The enhanced efficiency of CO2 assimilation in the pyrenoid via CCM had been modelled theoretically as a requirement for successful CCM in higher plant systems. The ultimate aim of my research is to understand the biogenesis of the pyrenoid using a set of CCM mutants with pyrenoidal defects. Immunofluorescence methods and spot growth tests under different CO2 concentrations were performed on mutants with CCM defects generated by an insertional mutagenesis screen. Morphological and physiological characterisation of these mutants revealed differences in the pyrenoid morphology, the ability for RuBisCO to aggregate into the pyrenoid and the formation of thylakoidal tubule network associated with the pyrenoid. The thylakoid tubule network may be linked to the transport of inorganic carbon into the pyrenoid as part of the CCM. Further characterisation of one of the mutants gave rise to the hypothesis that the gene of interest, Cre11.g467712 (SAGA), is a multi-functional anchor protein related to the structural formation of the pyrenoid and may be another essential component of the pyrenoid.
4

EFFECTS OF ADDITIONAL SODIUM BICARBONATE ON EXTRA/INTRA CELLULAR FACTORS IN A CONTINUOUS FLOW BIOREACTOR FOR THE PRODUCTION OF TISSUE ENGINEERED ARTICULAR CARTILAGE

Khan, AASMA ARIF 31 October 2012 (has links)
Articular cartilage has a low propensity for self-repair, due to which 27 million people are affected by osteoarthritis every year in North America. The current repair techniques used for cartilage defects possess flaws that reduce long-term clinical success. Tissue engineering carries with it the promise of engineering hyaline-like cartilage with physical and biochemical properties, similar to that of native cartilage. This being said, the primary objective of my project was to engineer clinically relevant sized articular cartilage constructs. To achieve my objective, first, I investigated the effect of continuous culture on cartilaginous tissue growth. Constructs grown under continuous media flow significantly accumulated more collagen and glycosaminoglycan, and displayed a stratified morphology, similar to that found in native cartilage. The second goal was to further increase chondrocyte proliferation, and extracellular matrix (ECM) accumulation. To achieve this, constructs were grown in a bioreactor with media supplemented with 14 mM sodium bicarbonate (NaHCO3). Constructs cultivated in the bioreactor with NaHCO3 supplementation exhibited a significant (p<0.05) increase in ECM accumulation (a 98-fold increase in glycosaminoglycans and a 25-fold increase in collagen content), cell proliferation (a 13-fold increase), and thickness (a 28-fold increase) compared to all other conditions (static and reactor without NaHCO3 supplementation). The third goal was to engineer cartilage constructs with as little cells as possible, reducing donor site morbidity. From the results obtained, it was evident that the monolayer constructs outperformed all the other constructs (pellet, biopsy, and minced). The final goal was to understand the underlying reason for the increased proliferation. First, I investigated if there were any differences present in intracellular pH (pHi) and intracellular buffering capacity. Second, I determined the role of extracellular pH (pHe) on cell proliferation. In an effort to accurately achieve this, I, for the first time, have reported on measuring pHi of chondrocytes while still in culture (2D and 3D cultures) using a confocal microscope. This study demonstrated the importance of extracellular environments, such as pHe, extracellular buffering capacity, and the presence of carbon dioxide and bicarbonate ions for chondrocyte proliferation. / Thesis (Ph.D, Chemical Engineering) -- Queen's University, 2012-10-30 19:19:32.026
5

Simulating Co2 Sequestration In A Depleted Gas Reservoir

Ozkilic, Ismet Oke 01 September 2005 (has links) (PDF)
Carbon dioxide is one of the greenhouse gases which have strong impacts on the environment and its amount in the atmosphere is far beyond to be ignored. Carbon dioxide levels are projected to be reduced by sequestering it directly to the underground. High amounts of carbon dioxide can be safely stored in underground media for very long time periods. Storage in depleted gas reservoirs provides an option for sequestering carbon dioxide. In 2002, production of Kuzey Marmara gas reservoir has been stopped due to gas storage plans. Carbon dioxide sequestration in Kuzey Marmara field has been considered in this study as an alternative to the gas storage projects. Reservoir porosity and permeability maps were prepared with the help of Surfer software demo version. These maps were merged with the available Kuzey Marmara production information to create an input file for CMG-GEM simulator and a three dimensional model of the reservoir was created. History match of the field model was made according to the 1998-2002 production data to verify the similarity between the model and actual reservoir. Kuzey Marmara field is regarded as a candidate for future gas storage projects. The reservoir still contains producible natural gas. Four different scenarios were prepared by considering this fact with variations in the regional field properties and implemented into previously built simulation model. These scenarios primarily focus on sequestering carbon dioxide while producing as much as natural gas possible. After analyzing the results from the scenarios it is realized that / CO2 injection can be applied to increase natural gas recovery of Kuzey Marmara field but sequestering high rate CO2 emissions is found out to be inappropriate.
6

Green Anesthesia : Use of Inhalational Anesthetics and their Effect on our Climate / Miljövänlig Anestesi : Användning av inhalationsanestetika och dess påverkan på vårt klimat

Karchut, Sabina, Wedahl, Skylar January 2023 (has links)
This thesis has, commissioned by Dräger, an international company at the forefront of medical and safety technology, examined how the use of inhalational anesthetics affects the climate and environment. The purpose of this work is to examine how the Swedish healthcare sector currently works with inhalational anesthetics, how different anesthetic machines affect the emissions, as well as alternatives available to reduce anesthetic gases emissions. Climate change is a current issue in today’s society, but the impact of anesthetic gases on the climate is not widely known, despite their everyday use in the healthcare sector. Through data collection from two Swedish hospitals; Linköping University Hospital and Örebro University Hospital, an interview with medical and medical engineering staff, as well as a literature study the main question of the thesis could be answered; How do the most common anesthetic gases affect the environment? The results are presented in the form of diagrams showing the amount of anesthetic gas used in the aforementioned hospitals during surgeries. The results have been analyzed and discussed based on the research questions, and the different results from each hospital have been compared to each other. It can be seen that Dräger’s anesthesia machines have a relatively low consumption of sevoflurane, but it is impossible to draw any definitive conclusions due to lack of data, and lack of access to machines from other manufacturers. / Detta examensarbete har, på uppdrag av Dräger, ett internationellt företag i framkant inom medicin- och säkerhetsteknik, undersökt hur användning av inhalationsanestetika påverkar miljön. Målet med arbetet är att undersöka hur den svenska sjukvården för närvarande arbetar med inhalationsanestetika, hur olika anestesimaskiner påverkar utsläppen, samt alternativ som finns tillgängliga för att minska dessa utsläpp. Klimatförändringar är en aktuell fråga i dagens samhälle men påverkan av anestesigaser på klimatet är inte allmänt känt, trots att dessa används dagligen i hälsovården. Genom datainsamling från två svenska sjukhus; Linköpings Universitetssjukhus och Örebro Universitetssjukhus, intervjuer med medicinsk- och medicinteknisk personal, samt en litteraturstudie har arbetets problemställning besvarats; Hur påverkar de mest frekvent använda anestesigaserna miljön? Resultaten visar i diagramform hur mycket anestesi gas som använts i tidigare nämnda sjukhus under operationer. Resultaten har analyserats och diskuterats utifrån forskningsfrågorna, dessutom har de olika resultaten från respektive sjukhus jämförts med varandra. Det kan ses att Drägers anestesimaskiner har en relativt låg konsumtion av sevofluran, men brist på data samt brist på tillgång till maskiner från andra producenter gör det omöjligt att dra en konkret slutsats.

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