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AbstractAutotrophs play an essential role in the cycling of carbon and nutrients, yet disease‐ecosystem relationships are often overlooked in these dynamics. Importantly, the availability of elemental nutrients like nitrogen and phosphorus impacts infectious disease in autotrophs, and disease can induce reciprocal effects on ecosystem nutrient dynamics. Relationships linking infectious disease with ecosystem nutrient dynamics are bidirectional, though the interdependence of these processes has received little attention. We introduce disease‐mediated nutrient dynamics (DND) as a framework to describe the multiple, concurrent pathways linking elemental cycles with infectious disease. We illustrate the impact of disease–ecosystem feedback loops on both disease and ecosystem nutrient dynamics using a simple mathematical model, combining approaches from classical ecological (logistic and Droop growth) and epidemiological (susceptible and infected compartments) theory. Our model incorporates the effects of nutrient availability on the growth rates of susceptible and infected autotroph hosts and tracks the return of nutrients to the environment following host death. While focused on autotroph hosts here, the DND framework is generalizable to higher trophic levels. Our results illustrate the surprisingly complex dynamics of host populations, infection patterns, and ecosystem nutrient cycling that can arise from even a relatively simple feedback between disease and nutrients. Feedback loops in disease‐mediated nutrient dynamics arise via effects of infection and nutrient supply on host stoichiometry and population size. Our model illustrates how host growth rate, defense, and tissue chemistry can impact the dynamics of disease–ecosystem relationships. We use the model to motivate a review of empirical examples from autotroph–pathogen systems in aquatic and terrestrial environments, demonstrating the key role of nutrient–disease and disease–nutrient relationships in real systems. By assessing existing evidence and uncovering data gaps and apparent mismatches between model predictions and the dynamics of empirical systems, we highlight priorities for future research intended to narrow the persistent disciplinary gap between disease and ecosystem ecology. Future empirical and theoretical work explicitly examining the dynamic linkages between disease and ecosystem ecology will inform fundamental understanding for each discipline and will better position the field of ecology to predict the dynamics of disease and elemental cycles in the context of global change.

This study was designed to test the hypothesis that chronic prenatal ethanol exposure decreases basal and stimulated L-glutamate release in the hippocampus of young, postnatal guinea pigs. Timed, pregnant guinea pigs were randomly assigned to one of the following three chronic treatment groups: 4 g ethanol/kg maternal body weight/day, isocaloric-sucrose and pair-feeding to the ethanol group, and water. Each oral treatment was given daily throughout gestation. Spontaneous locomotor activity was increased on postnatal day (PD) 10, and brain and hippocampal weights were decreased on PD 12 in the offspring of the ethanol group compared with the isocaloric-sucrose/pair-fed and water groups. On PD 12, the 45 mM K(+)- and 10 microM veratridine-stimulated release of glutamate in transverse hippocampal slices was decreased in the ethanol group compared with the two control groups. This alteration in glutamate release produced by chronic prenatal ethanol exposure may decrease the efficiency of excitatory synaptic transmission in the hippocampus during postnatal life.

Alcoholism and alcohol abuse represent a significant medical and societal problem, and have been thoroughly investigated in humans as well as using animal models. A less well understood aspect of alcohol related disorders is the possible effect of this drug on offspring whose parents were exposed prior to conception. The zebrafish has been successfully employed in alcohol research, however, the effect of exposing the parents to alcohol before fertilization of the eggs on offspring has not been demonstrated in this species. In this proof of concept study, we attempt to address this hiatus. We exposed both adult male and female zebrafish to 0.0% (control) or 0.5% (vol/vol) alcohol chronically for 7 days, subsequently bred the fish within their respective treatment group, collected the fertilized eggs, allowed them to develop, and tested the behavior of free-swimming offspring at their age of 7-9 days post-fertilization. We conducted the analysis in two genetically distinct quasi-inbred strains of zebrafish, AB and TL. Although gross morphology and general activity of the fish appeared unaffected, we found significant behavioral alterations in offspring of alcohol exposed parents compared to offspring of control parents in both strains. These alterations included robustly increased duration and reduced frequency of immobility, increased turn angle, and increased intra-individual variance of turn angle in offspring of alcohol exposed parents in both strains. The mechanisms underlying these behavioral effects or whether the effects are due to exposure of the father, the mother, or both to alcohol are unknown. Nevertheless, our results now set the stage for future studies with zebrafish that will address these questions.

Polymer electrolyte membrane (PEM) fuel cells convert the chemical energy of hydrogen and oxygen directly into electrical energy. Waste heat and water are the reaction by-products, making PEM fuel cells a promising zero-emission power source for transportation and stationary co-generation applications. In this study, a mathematical model of a PEM fuel cell stack is formulated. The distributions of the pressure and mass flow rate for the fuel and oxidant streams in the stack are determined with a hydraulic network analysis. Using these distributions as operating conditions, the performance of each cell in the stack is determined with a mathematical, single cell model that has been developed previously. The stack model has been applied to PEM fuel cell stacks with two common stack configurations: the U and Z stack design. The former is designed such that the reactant streams enter and exit the stack on the same end, while the latter has reactant streams entering and exiting on opposite ends. The stack analysed consists of 50 individual active cells with fully humidified H2 or reformate as fuel and humidified O2 or air as the oxidant. It is found that the average voltage of the cells in the stack is lower than the voltage of the cell operating individually, and this difference in the cell performance is significantly larger for reformate/air reactants when compared to the H2/O2 reactants. It is observed that the performance degradation for cells operating within a stack results from the unequal distribution of reactant mass flow among the cells in the stack. It is shown that strategies for performance improvement rely on obtaining a uniform reactant distribution within the stack, and include increasing stack manifold size, decreasing the number of gas flow channels per bipolar plate, and judicially varying the resistance to mass flow in the gas flow channels from cell to cell. Copyright © 2004 John Wiley & Sons, Ltd.

Abstract In this article, the novel concept of using magnetic nanofluidic electrolyte for redox flow batteries is demonstrated for the first time. In this regard, the stable magnetic nanofluidic electrolytes are prepared by dispersing magnetic modified multiwalled carbon nanotubes (MMWCNTs) in the positive electrolyte of a polysulfide-iodide redox flow battery at mass concentrations of less than 0.3 g L−1. The electrochemical behavior of magnetic nanofluidic electrolyte was examined using cyclic voltammetry at different mass concentrations of MMWCNTs with a carbon felt electrode. Higher and stable peak current densities were observed at larger mass concentrations of MMWCNTs. A polysulfide-iodide redox flow battery was employed to evaluate the influence of magnetic nanofluidic electrolyte on the battery performance for various mass concentrations, velocities of flowing electrolyte, and current densities using electrochemical impedance spectroscopy, polarization, and galvanostatic charge-discharge experiments. A decrease in ohmic resistance as well as reductions in the charge-transfer and mass-transfer resistances were observed for the magnetic nanofluidic electrolyte compared to those obtained in the absence of MMWCNTs. Adding MMWCNTs to the positive electrolyte at the mass concentration of 0.3 g L−1 results in enhanced performance of the polysulfide-iodide redox flow battery, whereby the peak power density increases by 45% and an energy efficiency of 79.91% was obtained at a current density of 20 mA cm−2. Moreover, high coulombic efficiency close to 100% and stable cycling performance over 200 cycles were achieved using magnetic nanofluidic electrolyte. After 50 cycles, at a current density of 30 mA cm−2, the energy efficiency of the battery operated with magnetic nanofluidic electrolyte remains 10% greater than that obtained in the absence of MMWCNTs. Besides improving the battery performance, MMWCNTs can be separated and recovered using magnetic decantation during electrolyte replacement for redox flow batteries involving high capacity fade and precipitation, which preserves system cost-benefits. The magnetic nanofluidic electrolyte could be applied for different redox solutions using appropriate magnetic nanoscale conductors. This innovative concept opens up a new opportunity to develop the next generation of high-performance and low-cost flow batteries.

Abstract The present paper investigates the performance of a solid oxide fuel cell based on proton-conducting electrolyte (SOFC-H+) using one-dimensional steady-state model. The analysis covers a detailed electro-chemical model for H2 and NH3 fuels. The direct internal reforming of NH3 is examined, and the effects of some operating parameters (e.g. temperature, pressure, fuel utilization and oxidant utilization) on the reversible cell potential are investigated. In addition, the overpotentials (including activation, ohmic and concentration) are calculated to study the irreversible behavior of the SOFC-H+ with some actual data operating conditions and material properties taken from the literature. In addition, effects of some operation and structural parameters on cell performance were examined. The present results indicate that the activation and the ohmic losses are considerable. The concentration overpotential at the anode side is negligible due to the fact that H2O is produced at the cathode side. The maximum power density is calculated as 3212 and 3113 W/m2 at 1073 K and 1 atm for the fuels of H2 and NH3. The results further show that H2 provides better performance than NH3 at the same partial pressure. Moreover, NH3 is an excellent hydrogen carrier which is a potential candidate for SOFC-H+ due to its high hydrogen content and considerable cell performance.

Abstract The modeling of fuel cells requires the coupling of fluid transport with electro-chemical reactions. There are two approaches commonly used. Firstly, the electrodes can be treated as two planes, where the potential gradient can be considered as being locally one-dimensional. In this case a two dimensional current density distribution is obtained. Secondly, the two electrode layers can be spatially resolved and the protonic and electronic potentials obtained by solving a pair of coupled Poisson equations. The latter approach requires much higher computational resources, because a higher spatial resolution is required and a large set of model parameters is required. On the other hand, much more detailed local information can be obtained by this method. The motivation for this study was to compare the results quantitively with detailed experimental data for a high temperature polymer electrolyte fuel cell with a geometric area of 200 cm2. Both model approaches show very good agreement with measured local current density distributions. The second model is able to provide a deeper insight into the current density variation through the membrane and catalyst layers and reveals points with local extremes. The present results are specific for high temperature polymer electrolyte fuel cells but the conclusions may readily be applied to the modeling of other high temperature fuel cell types.

Background: Alcohol use is a key preventable risk factor for serious injury. To effectively prevent alcohol-related injuries, we rely on the accurate surveillance of alcohol involvement in injury events. This often involves the use of administrative data, such as International Statistical Classification of Diseases and Related Health Problems, Tenth Revision, Australian Modification (ICD-10-AM) coding. Objective: To evaluate the completeness and accuracy of using administrative coding for the surveillance of alcohol involvement in major trauma injury events by comparing patient blood alcohol concentration (BAC) with ICD-10-AM coding. Method: This retrospective cohort study examined 2918 injury patients aged ≥18 years who presented to a major trauma centre in Victoria, Australia, over a 2-year period, of which 78% ( n = 2286) had BAC data available. Results: While 15% of patients had a non-zero BAC, only 4% had an ICD-10-AM code suggesting acute alcohol involvement. The agreement between blood alcohol test results and ICD-10-AM coding of acute alcohol involvement was fair ( κ = 0.33, 95% confidence interval: 0.27–0.38). Of the 341 patients with a non-zero BAC, 82 (24.0%) had ICD-10-AM codes related to acute alcohol involvement. Supplementary factors Y90 Evidence of alcohol involvement determined by blood alcohol level codes, which specifically describe patient BAC, were assigned to just 29% of eligible patients with a non-zero BAC. Conclusion: ICD-10-AM coding underestimated the proportion of alcohol-related injuries compared to patient BAC. Implications: Given the current role of administrative data in the surveillance of alcohol-related injuries, these findings may have significant implications for the implementation of cost-effective strategies for preventing alcohol-related injuries.

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