A Long‐Cycle‐Life Lithium–CO2 Battery with Carbon Neutrality

Lithium–CO₂ batteries are attractive energy‐storage systems for fulfilling the demand of future large‐scale applications such as electric vehicles due to their high specific energy density. However, a major challenge with Li–CO₂ batteries is to attain reversible formation and decomposition of the Li₂CO₃ and carbon discharge products. A fully reversible Li–CO₂ battery is developed with overall carbon neutrality using MoS₂ nanoflakes as a cathode catalyst combined with an ionic liquid/dimethyl sulfoxide electrolyte. This combination of materials produces a multicomponent composite (Li₂CO₃/C) product. The battery shows a superior long cycle life of 500 for a fixed 500 mAh g^?1 capacity per cycle, far exceeding the best cycling stability reported in Li–CO₂ batteries. The long cycle life demonstrates that chemical transformations, making and breaking covalent C? O bonds can be used in energy‐storage systems. Theoretical calculations are used to deduce a mechanism for the reversible discharge/charge processes and explain how the carbon interface with Li₂CO₃ provides the electronic conduction needed for the oxidation of Li₂CO₃ and carbon to generate the CO₂ on charge. This achievement paves the way for the use of CO₂ in advanced energy‐storage systems.     

Modeling Enterococcus densities measured by quantitative polymerase chain reaction and membrane filtration using environmental conditions at four Great Lakes beaches

Data collected by the US Environmental Protection Agency (EPA) during the summer months of 2003 and 2004 at four US Great Lakes beaches were analyzed using linear regression analysis to identify relationships between meteorological, physical water characteristics, and beach characteristics data and the fecal indicator bacteria, Enterococcus. Water samples were analyzed for Enterococcus densities by quantitative polymerase chain reaction (qPCR) and membrane filtration (MF). This paper investigates the ability of regression models to accurately predict Enterococcus densities above or below a threshold value, using environmental data on a beach-by-beach basis for both methods. The ability to create statistical models for real-time water quality analysis would allow beach managers to make more accurate decisions regarding beach safety. Results from linear regression models indicate that environmental factors explain more of the variability in Enterococcus densities measured by MF than Enterococcus densities measured by qPCR. Results also show that models for both methods did not perform well at predicting occurrences in which water quality levels exceeded a threshold.     

美国Highland铀矿碱法地浸采铀工艺(续完)

Highiand铀矿是西方国家最大的铀地浸矿山之一，采用典型的美国碱法地浸工艺，即以CO2和O2配制溶浸剂进行浸出。介绍了Highland铀矿采用的井场设计与建设、环境评价与监测、生产操作和地下水复原等方法，以及Highland铀矿的地质概况。     

Optimization of hydrogen stations in Florida using the Flow-Refueling Location Model

This paper develops and applies a model that locates hydrogen stations to refuel the maximum volume of vehicle flows. Inputs to the model include a road network with average speeds; the origin–destination flow volumes between each origin and destination; a maximum driving range between refueling stops; and the number of stations to build. The Flow-Refueling Location Model maximizes the flow volumes that can be refueled, measured either in number of trips or vehicle-miles traveled. Geographic Information Systems and heuristic algorithms are integrated in a spatial decision support system that researchers can use to develop data, enter assumptions, analyze scenarios, evaluate tradeoffs, and map results. For the Florida Hydrogen Initiative, we used this model to investigate strategies for rolling out an initial refueling infrastructure in Florida at two different scales of analysis: metropolitan Orlando and statewide. By analyzing a variety of scenarios at both scales of analysis, we identify a robust set of stations that perform well under a variety of assumptions, and develop a strategy for phasing in clustered and connecting stations in several stages or tiers.     

Detecting and ordering salient regions

We describe an ensemble approach to learning salient regions from arbitrarily partitioned data. The partitioning comes from the distributed processing requirements of large-scale simulations. The volume of the data is such that classifiers can train only on data local to a given partition. Since the data partition reflects the needs of the simulation, the class statistics can vary from partition to partition. Some classes will likely be missing from some or even most partitions. We combine a fast ensemble learning algorithm with scaled probabilistic majority voting in order to learn an accurate classifier from such data. Since some simulations are difficult to model without a considerable number of false positive errors, and since we are essentially building a search engine for simulation data, we order predicted regions to increase the likelihood that most of the top-ranked predictions are correct (salient). Results from simulation runs of a canister being torn and from a casing being dropped show that regions of interest are successfully identified in spite of the class imbalance in the individual training sets. Lift curve analysis shows that the use of data driven ordering methods provides a statistically significant improvement over the use of the default, natural time step ordering. Significant time is saved for the end user by allowing an improved focus on areas of interest without the need to conventionally search all of the data.     

Multitasking across generations: Multitasking choices and difficulty ratings in three generations of Americans

This study investigated whether changes in the technological/social environment in the United States over time have resulted in concomitant changes in the multitasking skills of younger generations. One thousand, three hundred and nineteen Americans from three generations were queried to determine their at-home multitasking behaviors. An anonymous online questionnaire asked respondents to indicate which everyday and technology-based tasks they choose to combine for multitasking and to indicate how difficult it is to multitask when combining the tasks. Combining tasks occurred frequently, especially while listening to music or eating. Members of the “Net Generation” reported more multitasking than members of “Generation X,” who reported more multitasking than members of the “Baby Boomer” generation. The choices of which tasks to combine for multitasking were highly correlated across generations, as were difficulty ratings of specific multitasking combinations. The results are consistent with a greater amount of general multitasking resources in younger generations, but similar mental limitations in the types of tasks that can be multitasked.     

Interpreting enhanced Hg oxidation with Br addition at Plant Miller

This paper introduces the first detailed reaction mechanisms for Br/Hg chemistry in flue gas, and interprets the Hg oxidation performance across a broad range of Br injection rates in recent field tests at Plant Miller. Homogeneous chemistry with Br species is much faster than with Cl species because the Br atom concentrations at the furnace exit are three to four orders of magnitude greater. The dominant channels with Br are analogous to those for Cl, whereby a Br atom partially oxidizes Hg⁰ into HgBr which is then oxidized into HgBr₂ by Br₂. Mercury also oxidizes heterogeneously on unburned carbon (UBC) with Br species. This mechanism is also analogous to the surface mechanism for Cl species, except that (i) Hg⁰ adsorption is faster on brominated sites and (ii) the high Br atom concentrations promote recombination reactions which maintain very low surface coverages of Hg/Br species. Hence, Br addition does not promote the production of particulate-Hg. Catalytic Hg⁰ oxidation on SCR monoliths by Br species is more than 40 times faster than by Cl species and follows a similar mechanism. For all Br loadings over 10 ppmw in the field tests, essentially all Hg⁰ entering the SCR was oxidized.     

Comparison of methods for fluorescent detection of viable, dead, and total Escherichia coli O157:H7 cells in suspensions and on apples using confocal scanning laser microscopy following treatment with sanitizers

The influence of treating Escherichia coli O157:H7 cells labeled with an enhanced green fluorescent protein (EGFP) plasmid with 20 microg/ml active chlorine, 100 mg/ml hydrogen peroxide, and 80 mg/ml acetic acid on fluorescence intensity was determined. In addition, fluorescent staining methods to differentiate viable and dead E. coli O157:H7 cells on the cuticle of Red Delicious cv. apples following treatment with water or 200 microg/ml active chlorine were evaluated. Suspensions of E. coli O157:H7 EGFP+ cells were exposed to chemical treatment solutions for 0, 30, 60, 120, or 300 s before populations (log10 cfu/ml) were determined by surface plating, and fluorescence intensities of suspensions and individual cells were measured using spectrofluorometry and confocal scanning laser microscopy (CSLM), respectively. The relative fluorescence intensity of suspensions and individual cells changed upon exposure to various treatments. Results indicate that the use of EGFP to tag E. coli O157:H7 may not be appropriate for investigations seeking to microscopically differentiate viable and dead cells on produce following surface treatment with sanitizers. SYTOX Orange and SYTOX Green nucleic acid stains fluorescently labeled dead E. coli O157:H7 cells attached to apple cuticles more intensely than did propidium iodide. A cross-signal occurred between CSLM photomultipliers when examining tissues treated with SYTOX Orange to detect dead cells and antibody labeled with Alexa Fluor 488 to detect total (dead and viable) cells. Because of the possibility of cross-signal resulting in an overestimation of the number of dead cells on apples and, perhaps, other produce treated with these stains, SYTOX Green is preferred to detect dead cells and antibody labeled with Alexa Fluor 594 is preferred to detect the total number of cells on apple surfaces following treatment with sanitizers. The performance of SYTOX Green in combination with Alexa Fluor 594 to detect dead and total cells of E. coli O157:H7 on other produce remains to be determined.