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| 2. |
- Sur, Dipika, et al.
(författare)
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Efficacy and safety of a modified killed-whole-cell oral cholera vaccine in India: an interim analysis of a cluster-randomised, double-blind, placebo-controlled trial.
- 2009
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Ingår i: Lancet. - 1474-547X. ; 374:9702, s. 1694-702
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Oral cholera vaccines consisting of killed whole cells have been available for many years, but they have not been used extensively in populations with endemic disease. An inexpensive, locally produced oral killed-whole-cell vaccine has been used in high-risk areas in Vietnam. To expand the use of this vaccine, it was modified to comply with WHO standards. We assessed the efficacy and safety of this modified vaccine in a population with endemic cholera. METHODS: In this double-blind trial, 107 774 non-pregnant residents of Kolkata, India, aged 1 year or older, were cluster-randomised by dwelling to receive two doses of either modified killed-whole-cell cholera vaccine (n=52 212; 1966 clusters) or heat-killed Escherichia coli K12 placebo (n=55 562; 1967 clusters), both delivered orally. Randomisation was done by computer-generated sequence in blocks of four. The primary endpoint was prevention of episodes of culture-confirmed Vibrio cholerae O1 diarrhoea severe enough for the patient to seek treatment in a health-care facility. We undertook an interim, per-protocol analysis at 2 years of follow-up that included individuals who received two completely ingested doses of vaccine or placebo. We assessed first episodes of cholera that occurred between 14 days and 730 days after receipt of the second dose. This study is registered with ClinicalTrials.gov, number NCT00289224. FINDINGS: 31 932 participants assigned to vaccine (1721 clusters) and 34 968 assigned to placebo (1757 clusters) received two doses of study treatment. There were 20 episodes of cholera in the vaccine group and 68 episodes in the placebo group (protective efficacy 67%; one-tailed 99% CI, lower bound 35%, p<0.0001). The vaccine protected individuals in age-groups 1.0-4.9 years, 5.0-14.9 years, and 15 years and older, and protective efficacy did not differ significantly between age-groups (p=0.28). We recorded no vaccine-related serious adverse events. INTERPRETATION: This modified killed-whole-cell oral vaccine, compliant with WHO standards, is safe, provides protection against clinically significant cholera in an endemic setting, and can be used in children aged 1.0-4.9 years, who are at highest risk of developing cholera in endemic settings. FUNDING: Bill & Melinda Gates Foundation, Swedish International Development Cooperation Agency, Governments of South Korea, Sweden, and Kuwait.
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| 3. |
- Kjeang, Erik, et al.
(författare)
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A Parametric Study of Methanol Crossover in a Flowing Electrolyte Direct Methanol Fuel Cell
- 2006
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Ingår i: Journal of Power Sources. - 0378-7753 .- 1873-2755. ; 153, s. 89-99
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Tidskriftsartikel (refereegranskat)abstract
- Direct methanol fuel cells (DMFCs) have significant potential to become a leading technology for energy conversion in a variety of applications. However, problems, such as methanol crossover reduce the efficiency and open circuit voltage of the cells. The novel design of flowing electrolyte-direct methanol fuel cells (FE-DMFCs) addresses this issue. Methanol molecules are effectively removed from the membrane electrode assembly (MEA) by the flowing electrolyte, and the unused fuel can be utilized externally. In this paper, a general 3D numerical computational fluid dynamics (CFD) model is established to simulate methanol crossover by convection–diffusion in the FE-DMFC. Illustrations of methanol concentration distribution and methanol molar flux densities are presented, and the performance is compared to conventional DMFCs. The results indicate that methanol crossover can be reduced significantly. A parameter study is performed where the influences of anode fuel feed concentration, electrolyte channel thickness and electrolyte volumetric flow rate on methanol crossover are evaluated. In addition, effects of various electrolyte channel orientations are determined. According to the simulations, counter flow is the superior choice of channel orientations to minimize crossover.
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| 4. |
- Kjeang, Erik, et al.
(författare)
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Modeling methanol crossover by diffusion and electro-osmosis in a flowing electrolyte direct methanol fuel cell
- 2005
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Ingår i: Fuel Cells. - Weinheim : Wiley-VCH Verlagsgesellschaft. - 1615-6846 .- 1615-6854. ; 5:4, s. 486-498
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Tidskriftsartikel (refereegranskat)abstract
- A CFD model is created to analyze methanol transport in a flowing electrolyte direct methanol fuel cell (FE-DMFC) by solving the 3D advection-diffusion equation, with consideration of electro-osmosis. The average methanol flux at the anode and cathode surfaces is simulated and compared to equivalent direct methanol fuel cells. Methanol crossover is defined as methanol flux at the cathode surface, and the results reveal that methanol crossover can be drastically reduced by the flowing electrolyte. The performance of the FE-DMFC at peak power current density is evaluated, and diffusion is shown to be the dominant contribution, although electro-osmosis increases with current density. The power consumption of the electrolyte pump is shown to be negligible compared to the cell power output. This indicates that thin electrolyte channels with high flow rates could further improve the efficiency
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