Two-stroke poppet-valved engines may combine the high power density of two - stroke engines and the low emissions of poppet-valved engines. A two-stroke diesel engine can generate the same power as a four-stroke engine of the same size, but at higher (leaner) air/fuel ratios. Diesel combustion at high air/fuel ratios generally means hydrocarbons, soot and carbon monoxide are oxidised more completely to water and carbon dioxide in the cylinder, and the opportunity to increase the rate of exhaust gas recirculation should reduce the formation of nitrogen oxides (NOx). The concept is being explored as a means of economically modifying diesel engines to make them cleaner and/or more powerful. This study details the application of two computational models to this problem. The first model is a relatively simple thermodynamic model created by the author capable of rapidly estimating the behaviour of entire engine systems. It was used to estimate near-optimum engine system parameters at single engine operating points and over a six-mode engine cycle. The second model is a detailed CFD model called KIVA-ERC. It is a hybrid of the KIVA engine modelling package developed at the Los Alamos National Laboratory and combustion and emissions subroutines developed at the University of Wisconsin-Madison Engine Research Center. It was used for detailed scavenging and combustion simulations and to provide estimates of emissions levels. Both models were calibrated and validated for four-stroke cycle operation using experimental data. The thermodynamic model was used to provide initial and boundary conditions to the KIVA-ERC model. Conversely, the combustion simulations were used to adjust zero-dimensional combustion correlations when experimental data was not available. Scavenging simulations were performed with shrouded and unshrouded intake valves. A new two-zone scavenging model was proposed and validated using multidimensional scavenging simulations. A method for predicting the behaviour of the two-stroke engine system based on four-stroke data has been proposed. The results using this method indicate that a four-stroke diesel engine with minor modifications can be converted to a two-stroke cycle and achieve substantially the same fuel efficiency as the original engine. However, emissions levels can not be predicted accurately without experimental data from a physical prototype. It is therefore recommended that such a prototype be constructed, based on design parameters obtained from the numerical models used in this study.

No description available.

<p>Electrostatic interaction is a strong force that attracts positively and negatively charged molecules to each other. Such an interaction is formed between positively charged polycationic polymers and negatively charged nucleic acids. In this dissertation, the electrostatic attraction between polycationic polymers and nucleic acids is exploited for applications in oral gene delivery and nucleic acid scavenging. An enhanced nanoparticle for oral gene delivery of a human Factor IX (hFIX) plasmid is developed using the polycationic polysaccharide, chitosan (Ch), in combination with protamine sulfate (PS) to treat hemophilia B. For nucleic acid scavenging purposes, the development of an effective nucleic acid scavenging nanofiber platform is described for dampening hyper-inflammation and reducing the formation of biofilms.</p><p>Non-viral gene therapy may be an attractive alternative to chronic protein replacement therapy. Orally administered non-viral gene vectors have been investigated for more than one decade with little progress made beyond the initial studies. Oral administration has many benefits over intravenous injection including patient compliance and overall cost; however, effective oral gene delivery systems remain elusive. To date, only chitosan carriers have demonstrated successful oral gene delivery due to chitosan’s stability via the oral route. In this study, we increase the transfection efficiency of the chitosan gene carrier by adding protamine sulfate to the nanoparticle formulation. The addition of protamine sulfate to the chitosan nanoparticles results in up to 42x higher in vitro transfection efficiency than chitosan nanoparticles without protamine sulfate. Therapeutic levels of hFIX protein are detected after oral delivery of Ch/PS/phFIX nanoparticles in 5/12 mice in vivo, ranging from 3 -132 ng/mL, as compared to levels below 4 ng/mL in 1/12 mice given Ch/phFIX nanoparticles. These results indicate the protamine sulfate enhances the transfection efficiency of chitosan and should be considered as an effective ternary component for applications in oral gene delivery.</p><p>Dying cells release nucleic acids (NA) and NA-complexes that activate the inflammatory pathways of immune cells. Sustained activation of these pathways contributes to chronic inflammation related to autoimmune diseases including systemic lupus erythematosus, rheumatoid arthritis, and inflammatory bowel disease. Studies have shown that certain soluble, cationic polymers can scavenge extracellular nucleic acids and inhibit RNA-and DNA-mediated activation of Toll-like receptors (TLRs) and inflammation. In this study, the cationic polymers are incorporated onto insoluble nanofibers, enabling local scavenging of negatively charged pro-inflammatory species such as damage-associated molecular pattern (DAMP) molecules in the extracellular space, reducing cytotoxicity related to unwanted internalization of soluble cationic polymers. In vitro data show that electrospun nanofibers grafted with cationic polymers, termed nucleic acid scavenging nanofibers (NASFs), can scavenge nucleic acid-based agonists of TLR 3 and TLR 9 directly from serum and prevent the production of NF-ĸB, an immune system activating transcription factor while also demonstrating low cytotoxicity. NASFs formed from poly (styrene-alt-maleic anhydride) conjugated with 1.8 kDa branched polyethylenimine (bPEI) resulted in randomly aligned fibers with diameters of 486±9 nm. NASFs effectively eliminate the immune stimulating response of NA based agonists CpG (TLR 9) and poly (I:C) (TLR 3) while not affecting the activation caused by the non-nucleic acid TLR agonist pam3CSK4. Results in a more biologically relevant context of doxorubicin-induced cell death in RAW cells demonstrates that NASFs block ~25-40% of NF-ĸβ response in Ramos-Blue cells treated with RAW extracellular debris, ie DAMPs, following doxorubicin treatment. Together, these data demonstrate that the formation of cationic NASFs by a simple, replicable, modular technique is effective and that such NASFs are capable of modulating localized inflammatory responses. </p><p>An understandable way to clinically apply the NASF is as a wound bandage. Chronic wounds are a serious clinical problem that is attributed to an extended period of inflammation as well as the presence of biofilms. An NASF bandage can potentially have two benefits in the treatment of chronic wounds by reducing the inflammation and preventing biofilm formation. NASF can prevent biofilm formation by reducing the NA present in the wound bed, therefore removing large components of what the bacteria use to develop their biofilm matrix, the extracellular polymeric substance, without which the biofilm cannot develop. The NASF described above is used to show the effect of the nucleic acid scavenging technology on in vitro and in vivo biofilm formation of P. aeruginosa, S. aureus, and S. epidermidis biofilms. The in vitro studies demonstrated that the NASFs were able to significantly reduce the biofilm formation in all three bacterial strains. In vivo studies of the NASF on mouse wounds infected with biofilm show that the NASF retain their functionality and are able to scavenge DNA, RNA, and protein from the wound bed. The NASF remove DNA that are maintaining the inflammatory state of the open wound and contributing to the extracellular polymeric substance (EPS), such as mtDNA, and also removing proteins that are required for bacteria/biofilm formation and maintenance such as chaperonin, ribosomal proteins, succinyl CoA-ligase, and polymerases. However, the NASF are not successful at decreasing the wound healing time because their repeated application and removal disrupts the wound bed and removes proteins required for wound healing such as fibronectin, vibronectin, keratin, and plasminogen. Further optimization of NASF treatment duration and potential combination treatments should be tested to reduce the unwanted side effects of increased wound healing time.</p> / Dissertation

Os processos de remoção de espécies químicas da atmosfera têm sido estudados atualmente utilizando modelos numéricos, na tentativa de compreender melhor, os processos de transferências de gases e material particulado (sejam elas naturais ou antropogênicas) intra-reservatórios na atmosfera e seus efeitos na dinâmica do tempo e clima. Neste estudo, foi utilizado o modelo RAMS para simular a estrutura vertical das nuvens que se desenvolvem na região amazônica, em conjunto ao modelo de remoção B. V. 2, para os processos de remoção úmida que ocorrem tanto dentro quanto abaixo da nuvem, além das condições atmosféricas locais da região da Bacia Amazônica para, assim, simular a transferência das espécies químicas da atmosfera para a hidrosfera dentro do escopo do projeto LBA. Dentro deste projeto, foram realizadas campanhas intensivas de medições, como a LBA/DRY-TO-WET e LBA/SMOCC (setembro a novembro de 2002) na região de Rondônia. No período das campanhas, foram realizadas medições das concentrações dos gases amônia, ácido nítrico e dióxido de enxofre, além das espécies inorgânicas solúveis em água, como amônio, nitrato e sulfato, entre outros. Estas concentrações de gases e partículas, bem como os parâmetros meteorológicos obtidos durante as campanhas, realizadas durante o período de transição entre as estações seca e chuvosa na região, foram utilizados como dados de entrada para ambos os modelos, onde foram escolhidos alguns eventos específicos. Com intuito de melhor representar o espectro de gotículas de nuvens no modelo de remoção, foram utilizadas a função de distribuição de Levine & Schwartz, 1982 e funções gama ajustadas aos dados observados em distribuição de gotículas de nuvem obtidas em vôos efetuados durante o experimento. Conseqüentemente, este trabalho visou à simulação da concentração na água de chuva de três espécies químicas (SO42-, NO3- e NH4+) removidas da atmosfera pelo evento de precipitação, comparando-as às composições químicas da água de chuva observadas experimentalmente, em dois eventos selecionados (9 e 10 de outubro de 2002). Simulações atmosféricas com o RAMS apresentaram resultados bastante satisfatórios conseguindo representar aspectos microfísicos das nuvens que se desenvolvem na região amazônica com bastante fidelidade. Os resultados da modelagem dos processos de remoção mostraram uma boa concordância com os observados, principalmente para o sulfato (que em alguns casos a quantidade encontrada na água de chuva pela simulação foi 97% da observada) em ambos os eventos, quando a altura da nuvem foi considerada mais realista para região (16 km). Além disso, observou-se que o espectro de gotículas de nuvem utilizado foi um parâmetro importante nos resultados. Os resultados mostraram ainda, uma predominância dos processos que ocorrem dentro da nuvem, sendo estes responsáveis por cerca de 80% a 97% da concentração da espécie química encontrada na água de chuva, corroborando a literatura. Com isso, ficou evidente a complexidade das interações e transferências entre os reservatórios atmosfera / hidrosfera através dos processos de remoção de poluentes, ressaltando assim, a importância dos estudos sobre este assunto. / The scavenging processes of chemical species have been studied using numerical modeling in order to understand the gases and particulate matter intra-reservoir transferences (natural or anthropogenic) which affect weather and climate. In this study RAMS model was used in turn to simulate cloud vertical structure formed over Amazonian area working together to B.V.2 scavenging model. The last model was used to simulate the in- and below-cloud scavenging processes, besides the local atmospheric conditions within the LBA Project. In this Project, there were evaluated many measurements of LBA/DRY-TO-WET and LBA/SMOCC (September to November) Campaigns at Rondonia State. During the Campaigns, ammonia, nitric acid and sulfur dioxide gases were evaluated and their respective particulate matter, ammonium, nitrate and sulfate, among others, as well as rainwater chemistry. These concentrations and meteorological parameters were also obtained, during the transition from dry to wet season, and used as input data to the both modeling, where some events were chosen. With the intention of modeling improvement, cloud droplet spectra were used from Levine & Schwartz, 1982 and gamma functions, according to each case and based on the droplet distribution obtained from flight collected data during the field Campaign. Consequently, this work simulated the rainwater concentrations of three chemical species (SO42-, NO3- e NH4+) scavenged from atmosphere by the precipitation event and compared to the observed data of two selected events (9 and 10 October 2002). RAMS atmospheric simulations presented satisfactory results which showed detailed cloud microphysics processes of Amazonian region. The modeling results show good agreement of observed data, mainly to sulfate, reaching 97% of the observed sulfate for both events, when the cloud height was considered more realistic for the region (16 km). Besides, the cloud droplet spectra were an important parameter to the modeling. The results also showed that the in-cloud process is responsible by 80% to 97% of the chemical species found in rainwater. Additionally, it was clear that the complexity of the interaction and intra-reservoir transferences through the scavenging processes and their importance.

This research is a result of a nine week field study during spring 2012, with the purpose of highlighting the stories of Dalit women in Madhya Pradesh, India. Together with a fellow student at Södertörn University, I investigated the Garima Campaign, an ActionAid project working with Dalit women forced to endure the illegal practice of manual scavenging, the manual removal of human excreta from dry toilets. This research was funded by a Minor Field Study scholarship provided by Swedish International Development Cooperation Agency (SIDA). In this paper I investigate how these oppressed women may change their life situation and self-image through participation in a group of peers striving towards the same goal, asking the questions: how do they narrate their former life as manual scavengers, what is it that persuaded them to join the campaign, and what kind of attitudes did they encounter from other members of society? Following this, focus is on communication and how it can contribute to improving the life conditions of people of low social status. The theories used for this purpose are intersectionality and empowerment, as well as Bourdieu’s concepts of habitus, field and symbolic violence. The data was drawn from interviews with female former manual scavengers, supported by observations of their life situation and on other background material. The results of this study corroborate the findings of much of the previous work in this field, especially in relation to the treatment of manual scavengers by the rest of society. However, there seemed to have been three major arguments that finally convinced the women to quit working as manual scavengers. The first one related to their feeling of dignity. The second one dealt with them being aware of their human rights, which supports the argument that awareness may lead to change. The third argument was an important pathos argument, and consisted of the fact that their children were mistreated in school and that the women did not want their children to feel bad about their social situation. In the Garima campaign the women are allowed to do things taboo for Indian women, especially for Dalit ones, like disturbing the existing system and standing up for their rights by kicking up a fuss. The campaign opened up a new arena in which they did not only work to abolish manual scavenging practices, but also worked to attack the caste system on the grass-roots level. In informing others, convincing them to stop the practice, the self-confidence of the women was strengthened further, as individuals and as a group.

The characteristics of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and the variation of the gas-particle partitioning of PCDD/Fs near two municipal solid waste incinerators (MSWIs) located in southern Taiwan were investigated. In order to better understand the mechanism of dry deposition, the atmospheric dry deposition flux and velocity of PCDD/Fs were calculated. It was found that the mean atmospheric PCDD/F concentrations (0.0348-0.106 pg I-TEQ/Nm3) were comparable to those detected in the vicinity of MSWIs in Taiwan, but significantly lower than those in a highly industrialized urban area (0.150 pg I-TEQ/Nm3) located in southern Taiwan. The relatively higher atmospheric PCDD/F concentrations was found in winter than in summer. The calculated total dry deposition flux of PCDD/Fs ranged from 0.0274-0.718 ng I-TEQ/m2-month, and the atmospheric deposition flux in winter tended to be higher than those in summer. The results also indicated that dry deposition velocities of atmospheric particles for each month ranged from 0.52-0.91 cm/s (mean = 0.63 cm/s) and 0.48-0.73 cm/s (mean = 0.55 cm/s) in sites A and B, respectively, which were similar to that for the ambient air near two MSWIs in Taiwan, but slightly higher than those in urban area of Korea. In addition, the dry deposition of PCDD/Fs was mainly contributed by particle-phase at both sampling areas during the estimated period. The above results demonstrated that the dominant mechanism of dry deposition was particle phase deposition. The annual variations of wet deposition of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in atmosphere were also measured at two sites (A and B). Results showed that particle scavenging dominates in the wet deposition processes for the removal of PCDD/Fs from the atmosphere, the highest value was observed at the highest chlorinated congener. The ambient temperature and the amount of precipitation played an important role in the variation of PCDD/F deposition fluxes. It was found that temperature was inversely associated with the existence of particulate PCDD/Fs, indicating PCDD/Fs are scavenged most efficiently in cold weather. PCDD/F wet deposition fluxes in rainy seasons (from June to August) were significantly higher than those in dry seasons (from December to February), revealing a positive relationship between wet deposition flux and monthly rainfall. Additionally, the annual total (dry + wet) deposition fluxes of PCDD/Fs were 149 ng/m2-year (5.02 ng I-TEQ/m2-year) and 177 ng/m2-year (5.11 ng I-TEQ/m2-year) for sites A and B, respectively, revealing that dry deposition was more dominant than the wet deposition for the atmospheric deposition of PCDD/Fs. Since atmospheric deposition is believed to be the main transfer pathway of PCDD/Fs into food chains, its impact on human exposure to PCDD/Fs is of great importance.

Staphylococcus aureus is one of the major causes of food-borne pathogenesis. Antibiotic consumption for these pathogens has been increasing year by year world-wide. In order to decrease the use of synthetic antibiotics, fresh fruits and dry herbs consumed as beverages in regular diets were examined as potential natural antibiotics for the treatment of food based infections against Staphylococcus aureus. Herbs consumed as tea infusions including Pimpinella anisum L. (anise), Anthemis arvensis L. (camomile), Rosa canina L. (rosehip), Salvia fruticosa Mill (sage) and fresh fruit juices including Vitis vinifera L. (grape), Citrus sinensis L. (orange), Prunus persica L. (peach) and Punica granatum L. (pomegranate) were selected as samples of hot or cold consumed beverages in our daily diets. Extracts of fresh fruit juices were prepared in methanol, on the other hand, tea infusions of herbs were filtered and lyophilized. Antioxidant capacities of the plant samples were investigated by radical scavenging methods, namely 2&rsquo / 2-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) as well as determination of total phenolic and flavonoid contents. Furthermore, antimicrobial activities of plant samples were determined by minimum inhibitory concentration and minimum bactericidal concentration methods along with disc diffusion method. Trolox equivalent antioxidant capacities (TEAC) of the herbal tea infusions obtained by ABTS radical scavenging method were ranged between 48.38 &plusmn / 1.242 and 715.73 &plusmn / 4.265 (&mu / mol Trolox equivalent (TE)/g of extract) while, TEAC values of fresh fruits juices were between 26.86 &plusmn / 0.217 and 73.55 &plusmn / 0.973 (&mu / mol Trolox equivalent (TE)/g of extract). Moreover, EC50 values of the tea infusions obtained by DPPH radical scavenging method were ranged between 0.05 &plusmn / 0.001 and 1.53 &plusmn / 0.004 (mg/mL) while, EC50 values of the fruit juices were 1.6 &plusmn / 0.014 and 2 &plusmn / 0.093 (mg/mL). Total phenolic content of the plant samples tested in this study were varied from 1.383 (&mu / g gallic acid equivalent (GAE)/mg of extract) to 159.167 (&mu / g gallic acid equivalent (GAE)/mg of extract) and total flavonoid content varied from 0.111 (&mu / g quercetin equivalent (QE)/mg of extract) to 201.15 (&mu / g quercetin equivalent (QE)/mg of extract). Sage, orange and grape displayed higher antimicrobial activities with values of 1.5, 6 and 6 mg/mL minimum inhibitory concentrations and 1.5, 24 and 24 mg/mL minimum bactericidal concentrations, respectively. Inhibition zone diameters of sage, orange and grape were found to be 9, 9 and 11 mm.

In this study, the settling particulates collected by time-series sediment traps, sediment cores, and seawater samples taken in the western South Okinawa Trough were analyzed for 210Pb and 210Po in order to understand the characteristics of the particulates and sediments based on the distribution of these two nuclides and the extent of their radioactive disequilibrium. Two sediment traps were deployed at T18 (24¢X45'N 122¢X18'E, about 300m and 100m above bottom) from February to August 1999. The results show that higher mass fluxes were observed from February to April, ranging between 16 and 56 g/m2/d. The 210Pb activity increases systematically with time from about 80 to 100 dpm/g, and the upper trap has slightly higher values. Similar to 210Pb, the 210Po activity also increases, but from near zero to only 27 dpm/g for both traps, much lower than the corresponding 210Pb activity. The 210Pb activities are quite different between the settling particulates collected by traps at T18 and the surface sediment taken nearby (the former have a mean activity of about 85 to 90 dpm/g; the latter has a value of only 11 dpm/g). The size distribution and elemental composition are also different between the trapped particulates and the sediment. Thus the underlying sediments were not directly derived from the overlying trapped particulates. Except for T4 core below 15cm and T19 entire core, the 210Po/210Pb activity ratio in the sediments varies greatly, from near zero to 0.7, indicating deficiency of 210Po. Both 210Po and 210Pb activities are much lower in the sediments than in the settling particulates. A T19 both 210Po and 210Pb activities in the core decrease steeply from 120 dpm/g at surface to 60 dpm/g at 4 cm, indicating radioactive equilibrium. This is entirely different from the cores taken at other stations. The total 210Po/210Pb activity ratio in the water column at T17 is nearly constant at about 0.6, but drops to 0.3 below 700m, i.e. 210Po activity is deficient in the entire water column. At T18, the activity ratio is about 1.3 between 100m and 300m, indicating a 210Po excess in this layer. Below 400m, the ratio is about 0.6 to 0.7, showing 210Po deficit again. These observations indicate that the water columns at T17 and T18 are stratified, probably due to lateral transport. Based on the 210Po/210Pb activity ratio the mean residence time of 210Po with respect to particulate scavenging ranges from 3 to 16 months.

Atmospheric deposition of nitrogen species represents an additional nutrient source to natural environments, and can alter the nitrogen cycle by increasing nutrient levels beyond the requirements of organisms. In Tampa Bay, atmospheric deposition of dissolved inorganic nitrogen species (DIN) has been found to be the second largest nitrogen source, but little is known about dissolved organic nitrogen species (DON). The research goal was to improve the dry and wet deposition estimates by inclusion of the DON contribution. In the atmospheric chemistry field a standard method to measure DON in atmospheric samples has not been agreed upon. This research proposes the use of the ultraviolet (UV)-photolysis method and presents the optimal settings for its application on atmospheric samples. Using a factorial design scheme, experiments on surrogate nitrogen compounds, typically found in the atmosphere, indicated that DON can be xviii measured with no biases if optimal settings are fixed to be solution pH 2 with a 24-hr irradiance period. DIN species (NH4 +, NO2 -, NO3 -) and DON concentrations were determined in fine (PM2.5) and coarse particles (PM10-2.5) as well as in rainwater samples collected at Tampa Bay. The estimates of wet deposition fluxes for NH4 +, NO3 - and DON were 1.40, 3.18 and 0.34 kg-N ha-1yr-1, respectively. Hourly-measured gas concentrations and 24-hr integrated PM10 concentrations were used in conjunction with a below-cloud scavenging model to explain DIN and DON concentration in rainwater samples. Scavenging of aerosol-phase DON contributed only 0.9 ± 0.2% to rainwater DON concentrations, and therefore gas scavenging should be responsible for 99%. These results confirmed the existence of negative biases in the dry and wet deposition fluxes over Tampa Bay. There is increasing interest in simulating wet deposition fluxes, and the proposed below-cloud scavenging model offers a new computational approach to the problem. It integrates the typical gas and particle collection functions and the concept of the deposition-weighted average concentrations. The model uses mass balance to describe the time-dependent cumulative contribution of all droplets in the rain spectrum to the rainwater concentration, giving predictions closer to experimental values and better estimations than those reported in the literature for similar cases.

Polymers films and membranes with immobile and irreversible reactive sites can provide significant barrier properties for packaging materials. There is a need to develop mathematical models to understand the behavior of these reactive materials and to confidently extrapolate experimental data. Due to mechanical and optical requirements, barrier films may consist of composites, such as polymer blends and multilayer films with alternating reactive and inert layers. The reactive term that consumes the mobile species in the governing transport equations for such materials is a function of both the mobile species and the immobilized reactive sites, leading to non-linear partial differential equations that typically have to be solved numerically. Composite structures add to the complexity of the model. For the polymer blend, a multiscale model was developed, incorporating the reactive details within the particle into the bulk transport equation. For the multilayer film, initial conditions and diffusion coefficients were assigned independently for reactive or inert layers. The models developed for the three configurations were solved numerically over a wide parameter space. Three regimes were identified, namely early times characterized by an initial flux plateau, and intermediate regime, and long times, characterized by the time lag. Asymptotic analysis of the homogeneous model was used to develop analytical predictions for the three regimes, obviating the need to numerically solve the model’s non-linear equations. These predictions were generalized to polymer blends. For multilayer films, predictions for early and long times were developed. Results for polymer blends and multilayer composites were compared and discussions of the most suitable configuration for different scenarios were presented. The reactive barrier configurations studied require the knowledge of parameters such as reaction rates and coefficients of diffusion and solubility of the reactive polymer. Model and predictive equations have been developed to describe the transient mass uptake in reactive homogeneous films, enabling the extraction of these parameters from sorption experiments. / text