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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.
101

Investigation of the Chemical Pathway for Gaseous Nitrogen Dioxide Formation during Flue Gas Desulfurization with Dry Sodium Bicarbonate Injection

Stein, Antoinette Weil January 2001 (has links)
No description available.
102

Kortsiktiga effekter avbikarbonatbehandling pålungmossa i plantskola / Short term effects on liverwort treated with sodiumbicarbonate

Stenström, Manne January 2022 (has links)
Årligen producerar svenska skogsplantskolor runt 400 miljoner plantor till skogsbruket.Lungmossan är ett av de stora ogräsen för de skogliga plantskolorna. Lungmossan breder utsig på plantbäddarna och omöjliggör hanteringen av plantorna. Idag finns det inget tillåtetbekämpningsmedel för att bekämpa lungmossa på marknaden. Behandling av bikarbonat i fastform har visat goda resultat men är svåra att genomföra i stor skala. I detta arbete harmöjligheten att bekämpa lungmossa med vattenlöslig bikarbonatbehandling studerats.Ett plantskoleförsök genomfördes i ett av Skogforsks växthus i Sävar. Försöket bestod av tvåförstudier och sedan ett huvudförsök med 9 olika försöksuppställningar. Totalt ingick 49Starpot 50 kassetter med 24–48 granplantor i varje. Resultatet visade att det går att behandlalungmossa med bikarbonat utblandat med vatten kortsiktigt, men att de skadorna som uppstårunder behandling på granplantorna gör metoden irrelevant. I stället bör vidare studier påbikarbonat i fast form undersökas.
103

Controlled release floating multiparticulates of metoprolol succinate by hot melt extrusion

Malode, V.N., Paradkar, Anant R, Devarajan, P.V. 30 June 2015 (has links)
Yes / We present hot melt extrusion (HME) for the design of floating multiparticulates. Metoprolol succinate was selected as the model drug. Our foremost objective was to optimize the components Eudragit® RS PO, polyethylene oxide (PEO) and hydroxypropyl methylcellulose (HPMC) to balance both buoyancy and controlled release. Gas generated by sodium bicarbonate in acidic medium was trapped in the polymer matrix to enable floating. Eudragit® RS PO and PEO with sodium bicarbonate resulted in multiparticulates which exhibited rapid flotation within 3 minutes but inadequate total floating time (TFT) of 3 hours. Addition of HPMC to the matrix did not affect floating lag time (FLT), moreover TFT increased to more than 12 hours with controlled release of metoprolol succinate. Floating multiparticulates exhibited t50% of 5.24 hours and t90% of 10.12 hours. XRD and DSC analysis revealed crystalline state of drug while FTIR suggested nonexistence of chemical interaction between the drug and the other excipients. The assay, FLT, TFT and the drug release of the multiparticulates were unchanged when stored at 40 °C/75%RH for 3 months confirming stability. We present floating multiparticulates by HME which could be extrapolated to a range of other drugs. Our approach hence presents platform technology for floating multiparticulates.
104

Regulation of Duodenal Mucosal Barrier Function and Motility : The Impact of Melatonin

Sommansson, Anna January 2013 (has links)
The duodenal mucosa is regularly exposed to acid, digestive enzymes and ingested noxious agents. It is thus critical to maintain a protective barrier to prevent the development of mucosal injury and inflammation, which are often observed in situations when barrier function is impaired. The rate of mucosal bicarbonate secretion, the regulation of epithelial paracellular permeability and motility are each key components of duodenal barrier function. The hormone melatonin is present in high levels in the gastrointestinal tract and it has been hypothesized that melatonin exerts protective properties. This thesis aims to investigate the impact of exogenous melatonin on the regulation of duodenal barrier function and motility in anesthetized rats in vivo. In addition, duodenal tissue was examined histologically and the expression levels of tight junction proteins and melatonin receptors were assessed with qRT-PCR. It was found that melatonin stimulated mucosal bicarbonate secretion and decreased basal paracellular permeability. Exposing the duodenal mucosa to the well-characterized barrier breaker ethanol increased mucosal bicarbonate secretion, paracellular permeability and motility. Omission of luminal Clˉ abolished, while pretreatment with a nicotinic receptor antagonist reduced, the ethanol-induced bicarbonate secretion suggesting that the secretory response to ethanol is meditated via Clˉ/HCO3ˉexchangers and enteric neural pathways. Melatonin reduced the ethanol-induced increases in paracellular permeability and motility either when injected intravenously or when administered in drinking water for two weeks. The actions of melatonin were abolished by the melatonin receptor antagonist luzindole and by nicotinic acetylcholine receptor inhibition. Two weeks oral administration of melatonin up-regulated the expression levels of melatonin receptors, down-regulated the expression of ZO-3 while the expression of ZO-1, ZO-2, claudin 2-4, occludin and myosin light chain kinase were unaffected. Superficial epithelial changes in a few villi were seen in response to ethanol exposure, an effect that was histologically unchanged by melatonin pretreatment. In conclusion, the results suggest that melatonin plays an important role in the neurohumoral regulation of gastrointestinal mucosal barrier function and motility via receptor- and enteric neural-dependent pathways in vivo in rats. Melatonin might be a candidate for treatment of barrier dysfunction in humans.
105

Influence of Dusts on Premixed Methane-Air Flames

Ranganathan, Sreenivasan 30 March 2018 (has links)
Influence of dust particles on the characteristics of premixed methane-air flames has been studied in this dissertation. Experiments are performed in a Bunsen burner type experimental set-up called Hybrid Flame Analyzer (HFA), which can be used to measure the burning velocity of gas, dust, and hybrid (gas and dust) premixed flames at constant pressure operating conditions. In the current study, analysis of particle-gas-air system of different types of dust particles (at particle size, dp = 75-90 µm) in premixed methane-air (ϕg = 0.8, 1.0 and 1.2) flames. Coal, sand, and sodium bicarbonate particles are fed along with a premixed methane-air mixture at different concentrations (λp = 0-75 g/m3) in both laminar and turbulent conditions. First, the variation of laminar burning velocity with respect to the concentration of dust particles, and type of dusts are investigated for different equivalence ratios. Second, the laminar premixed flame extinction with inert and chemical suppressant particles are studied. Third, the variation of turbulent burning velocity of these hybrid mixtures are investigated against different turbulent intensities apart from the different concentrations and types of dusts. Fourth, the radiative fraction of heat released from turbulent gas-dust premixed flames are also presented against the operating parameters considered. Combustible dust deflagration hazard is normally quantified using the deflagration index (Kst) measured using a constant volume explosion sphere, which typically is a sealed 20-liter metal sphere where a premixed mixture is ignited at the center and the progression of the resulting deflagration wave is recorded using the pressure measured at the vessel wall. It has been verified from prior studies that the quantification of the turbulence by this method is questionable and there is a need to analyze the controlling parameters of particle-gas-air premixed system accurately through a near constant pressure operated experimental platform. Thus, the main objective of this study is to analyze the influence of dust particles on premixed methane-air flames at near constant pressure conditions. The turbulent burning velocity is calculated by averaging the measured flame heights and the laminar burning velocity is calculated through the premixed cone angle measurements from several high-speed shadowgraph images obtained from the experiments. The turbulent intensity and length scale of turbulence generated by a perforated plate in the burner is quantified from the hot-wire anemometer measurements. Radiative heat flux is also measured for each of the turbulent test conditions. The outcomes from these experiments are: 1. An understanding of the variation of turbulent burning velocity of gas-dust premixed flames as a function of dust type, turbulent intensity, integral length scale, dust concentration and gas phase mixture ratio. 2. An understanding of the flame extinction characteristics and variation of laminar burning velocity of gas-dust premixed flames as a function of dust concentration and gas phase mixture ratio. 3. Quantify the radiative heat flux and radiative fraction of heat released from gas-dust turbulent premixed flames as a function of dust type, turbulent intensity, dust concentration and gas phase mixture ratio. Dust type and concentration play an important role in deciding the trend in the variation of both laminar (SL) and turbulent burning velocity (ST). Coal particles, with the release of volatile (methane), tend to increase burning velocities except for fuel rich conditions and at higher coal concentrations at larger turbulent intensities. At a higher turbulent intensity and larger concentrations, higher ST values are observed with the addition of sand. Sodium bicarbonate addition, with the release of CO2 and H2O, decreased the burning velocity at all the concentrations, turbulent intensities and equivalence ratios. Laminar flame extinction was observed with the addition of sand and sodium bicarbonate particles at conditions exceeding certain critical dust concentrations. These critical concentrations varied with the equivalence ratios of gaseous premixed flames. The turbulence modulation exhibited by particles and particle concentration is evident in these observations. The independent characteristic time scale analysis performed using the experimental data provided further insights to the results. The chemical and convective times in gas phase confirm the broadened preheat thin reaction zone regime in the current test cases, which has an effect of attenuating turbulence and thereby the resulting turbulent burning velocity. The particle time scale analysis (Stokes number) show that the effect of particles and particle concentration is to slightly enhance the turbulence and increase the turbulent burning velocity at lower concentrations. However, the time scale analysis of particle vaporization (vaporization Damköhler number) indicate an increase in the vaporization rate for particles (coal and sodium bicarbonate) resulting in a decrease in their turbulent burning velocities at higher concentrations and turbulent intensities. Sodium bicarbonate has higher evaporation rate than coal at same level of turbulence and the absence of this effect for inert (sand) results in higher turbulent burning velocities at higher concentrations. An increase in the turbulent intensity increases the vaporization rate of particles. The investigation on radiative fraction of heat released by methane-air-dust turbulent premixed flames identified that, the addition of dust particles increases the radiative fraction irrespective of the dust type due to the radial and axial extension of flame. A unified approach to couple this multiple complex phenomenon of turbulence, particle interaction, particle vaporization and combustion in particle laden premixed gaseous flames is the direction for future research.
106

Stability of Extemporaneously Prepared Lansoprazole Suspension at Two Temperatures

Morrison, Jordan T., Lugo, Ralph A., Thigpen, Jim C., Brown, Stacy D. 01 January 2013 (has links)
OBJECTIVE The purpose of this study was to examine the stability of a generic lansoprazole product in a 3 mg/mL sodium bicarbonate suspension under room temperature and refrigerated conditions. METHODS Lansoprazole suspensions (3 mg/mL) were prepared in triplicate using an 8.4% sodium bicarbonate vehicle for each storage condition (room temperature and refrigerated). During 1 month, samples from each replicate were periodically removed and analyzed for lansoprazole concentration by liquid chromatography–tandem mass spectrometry (LC-MS/MS). Each sample was spiked with 10 mg/L omeprazole to serve as the internal standard. A positive electrospray LC-MS/MS method was validated over the calibration range of 5 to 25 mg/L using Food and Drug Administration Guidance. The identities of the analyte and internal standard in the samples were verified by monitoring the MS/MS transitions of m/z 370 to m/z 252 and m/z 346 to m/z 198 for lansoprazole and omeprazole, respectively. Additionally, the pH of the suspensions was monitored throughout the study. RESULTS The stability of lansoprazole in the oral sodium bicarbonate suspension under refrigeration is compromised prior to what has been previously reported in the literature. Samples kept at room temperature lost >10% of the lansoprazole after 48 hours compared with the refrigerated samples, which maintained integrity up to 7 days. No statistically significant difference was found between the pH of the room temperature and refrigerated suspension samples, indicating that this factor is not the cause for the differences in stability at these two conditions. CONCLUSIONS This study suggests that the extemporaneously compounded lansoprazole oral suspension prepared in 8.4% sodium bicarbonate should not be stored in plastic oral syringes longer than 48 hours at room temperature and no longer than 7 days when refrigerated. These data indicate an expiration time earlier than that previously reported for the refrigerated product (14 days).
107

Enhancement of menadione cytotoxicity by bicarbonate: redox cycling and a possible role for the carbonate radical in quinone cytotoxicity

Aljuhani, Naif Saad Unknown Date
No description available.
108

Evaluierung, Validierung und Anwendung eines Scores zur Stratifizierung des Risikos akuter Nierenfunktionsstörungen / Evaluation, validation and application of a predictive score for risk stratification of acute kidney injury after cardiac surgery

Wetz, Anna Julienne 07 May 2013 (has links)
No description available.
109

Hidratação com bicarbonato de sódio na prevenção de nefropatia induzida por contraste : estudo clínico multicêntrico

Gomes, Vitor Osório January 2009 (has links)
Introdução: Nefropatia induzida por contraste (NIC) está associada a piores desfechos intra-hospitalar e a longo prazo. Estudos recentes sugerem que hidratação com bicarbonato de sódio possa ser útil na sua prevenção; no entanto, essa medida de prevenção de NIC não foi, ainda, avaliada em pacientes diabéticos. Método: Subanálise de um estudo multicêntrico envolvendo 301 pacientes com creatinina sérica ≥ 1,2 mg/dl ou depuração de creatinina endógena (DCE) < 50 ml/min submetidos a cineangiocoronariografia ou angioplastia coronária, randomizados para receber hidratação com bicarbonato de sódio ou solução salina (soro fisiológico – SF) a 0,9%. Todos os procedimentos foram realizados com contraste iônico de baixa osmolaridade. Os desfechos avaliados foram incidência de NIC (definida como aumento de 0,5 mg/dl) e variação da creatinina e da DCE em 48 horas após o procedimento. Da totalidade de pacientes, 87 tinham diabetes melito e foram incluídos nesse subestudo. Resultados: Não houve diferença entre os grupos em relação a características demográficas, volume de contraste e níveis basais de creatinina e DCE. Entre os pacientes avaliados, 8 desenvolveram NIC: 4 (9,8%) pacientes no grupo bicarbonato e 4 (8,9%) no grupo SF 0,9% (p = 0,9). A variação da creatinina sérica e da DCE foi similar entre os grupos. Conclusão: Hidratação com bicarbonato de sódio não demonstrou benefício em reduzir a incidência de NIC em pacientes diabéticos submetidos a cateterismo cardíaco ou angioplastia coronária em comparação à hidratação com SF 0,9%. / Background: Contrast-induced nephropathy (CIN) is associated with worse clinical outcomes both at short and long-term follow-up. Recent evidence indicates that intravenous hydration with sodium-bicarbonate may reduce the incidence of CIN. However, this strategy has not been reported in diabetic patients. Methods: Sub-analysis of a multicenter study involving 301 patients with serum creatinine ≥ 1,2 mg/dL or creatinine clearance < 50 mL/min submitted to coronary angiography or percutaneous coronary intervention and randomized to intravenous hydration with sodium-bicarbonate or normal saline. All patients received low-osmolar contrast media. We assessed the incidence of CIN (defined as creatinine increase ≥ 0,5 mg/dL), and the average change in creatinine and creatinine clearance 48 hours after the procedure. A total of 87 diabetic patients were analyzed. Results: There was no difference between groups regarding baseline characteristics, contrast volume used, baseline creatinine levels and creatinine clearance. Eight patients presented CIN: 4 (9.8%) in the bicarbonate group and 4 (8.9%) in the saline group (p = 0.9). The average change in serum creatinine and creatinine clearance were similar between groups. Conclusion: Intravenous hydration with sodium-bicarbonate did not reduce the incidence of CIN in diabetic patients undergoing coronary angiography or percutaneous coronary intervention as compared to hydration with normal saline.
110

Hidratação com bicarbonato de sódio na prevenção de nefropatia induzida por contraste : estudo clínico multicêntrico

Gomes, Vitor Osório January 2009 (has links)
Introdução: Nefropatia induzida por contraste (NIC) está associada a piores desfechos intra-hospitalar e a longo prazo. Estudos recentes sugerem que hidratação com bicarbonato de sódio possa ser útil na sua prevenção; no entanto, essa medida de prevenção de NIC não foi, ainda, avaliada em pacientes diabéticos. Método: Subanálise de um estudo multicêntrico envolvendo 301 pacientes com creatinina sérica ≥ 1,2 mg/dl ou depuração de creatinina endógena (DCE) < 50 ml/min submetidos a cineangiocoronariografia ou angioplastia coronária, randomizados para receber hidratação com bicarbonato de sódio ou solução salina (soro fisiológico – SF) a 0,9%. Todos os procedimentos foram realizados com contraste iônico de baixa osmolaridade. Os desfechos avaliados foram incidência de NIC (definida como aumento de 0,5 mg/dl) e variação da creatinina e da DCE em 48 horas após o procedimento. Da totalidade de pacientes, 87 tinham diabetes melito e foram incluídos nesse subestudo. Resultados: Não houve diferença entre os grupos em relação a características demográficas, volume de contraste e níveis basais de creatinina e DCE. Entre os pacientes avaliados, 8 desenvolveram NIC: 4 (9,8%) pacientes no grupo bicarbonato e 4 (8,9%) no grupo SF 0,9% (p = 0,9). A variação da creatinina sérica e da DCE foi similar entre os grupos. Conclusão: Hidratação com bicarbonato de sódio não demonstrou benefício em reduzir a incidência de NIC em pacientes diabéticos submetidos a cateterismo cardíaco ou angioplastia coronária em comparação à hidratação com SF 0,9%. / Background: Contrast-induced nephropathy (CIN) is associated with worse clinical outcomes both at short and long-term follow-up. Recent evidence indicates that intravenous hydration with sodium-bicarbonate may reduce the incidence of CIN. However, this strategy has not been reported in diabetic patients. Methods: Sub-analysis of a multicenter study involving 301 patients with serum creatinine ≥ 1,2 mg/dL or creatinine clearance < 50 mL/min submitted to coronary angiography or percutaneous coronary intervention and randomized to intravenous hydration with sodium-bicarbonate or normal saline. All patients received low-osmolar contrast media. We assessed the incidence of CIN (defined as creatinine increase ≥ 0,5 mg/dL), and the average change in creatinine and creatinine clearance 48 hours after the procedure. A total of 87 diabetic patients were analyzed. Results: There was no difference between groups regarding baseline characteristics, contrast volume used, baseline creatinine levels and creatinine clearance. Eight patients presented CIN: 4 (9.8%) in the bicarbonate group and 4 (8.9%) in the saline group (p = 0.9). The average change in serum creatinine and creatinine clearance were similar between groups. Conclusion: Intravenous hydration with sodium-bicarbonate did not reduce the incidence of CIN in diabetic patients undergoing coronary angiography or percutaneous coronary intervention as compared to hydration with normal saline.

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