302 research outputs found
Metal–organic fireworks: MOFs as integrated structural scaffolds for pyrotechnic materials
A new approach to formulating pyrotechnic materials is presented whereby constituent ingredients are bound together in a solid-state lattice. This reduces the batch inconsistencies arising from the traditional approach of combining powders by ensuring the key ingredients are ‘mixed’ in appropriate quantities and are in intimate contact. Further benefits of these types of material are increased safety levels as well as simpler logistics, storage and manufacture. A systematic series of new frameworks comprising fuel and oxidiser agents (group 1 and 2 metal nodes & terephthalic acid derivatives as linkers) has been synthesised and structurally characterised. These new materials have been assessed for pyrotechnic effect by calorimetry and burn tests. Results indicate that these materials exhibit the desired pyrotechnic material properties and the effect can be correlated to the dimensionality of the structure. A new approach to formulating pyrotechnic materials is proposed whereby constituent ingredients are bound together in a solid-state lattice. A series of Metal–organic framework frameworks comprising fuel and oxidiser agents exhibits the desired properties of a pyrotechnic material and this effect is correlated to the dimensionality of the structure
Effects of crop type and harvest on nest survival and productivity of dickcissels in semi-natural grasslands
Recent focus on climate change and global energy production has increased interest in developing biofuels including perennial native grasses (e.g. switchgrass [Panicum virgatum]) as viable energy commodities while simultaneously maintaining ecosystem function and biodiversity. However, there is limited research examining the effects of biofuel-focused grasslands on grassland bird reproductive success and conservation. In 2011–2013 we studied the effects of vegetation composition and harvest regimens of switchgrass monocultures and native warm-season grass (NWSG) mixtures on nest success, nest density, and productivity for dickcissels (Spiza americana) in Clay Co. MS, USA. There was no effect of vegetation metrics, harvest frequency, or biofuel treatment on nest survival. However, both vegetation composition and harvest frequencies influenced nest density and productivity. Native warm season grasses contained 54–64 times more nests relative to switchgrass treatments, and nest density and productivity were 10% greater in single harvest plots. Our results suggest semi-natural grasslands can balance biofuel production, ecosystem functionality, and conservation so that biofuels offer an opportunity for wildlife conservation rather than a continued threat to grassland birds
Spatiotemporal Dynamics in Identification of Aircraft–Bird Strikes
A primary concern for human–wildlife interactions is the potential impacts resulting from wildlife (primarily birds) collisions with aircraft. The identification of species responsible for collisions with aircraft is necessary so that airport management can develop effective strategies to reduce strikes with those species. Of particular importance in developing such strategies is the identification of regional, seasonal, and temporal patterns in collisions with unidentified bird species that may limit the effectiveness of regional habitat management to reduce bird strikes. The authors analyzed 105,529 U.S. civil aviation strike records from 1990 to 2012 in the FAA’s National Wildlife Strike Database to examine patterns of collisions involving unidentified birds. Factors that affected identification were airport certification class, FAA region, mass of struck species, state species richness (if damage was reported), and interactive effects between the last four factors. Identification varied by region and declined with increasing species richness; this identification was greater for general aviation (GA) airports and the mass of struck species, especially when damage was reported. Species identification might be improved by increasing reporting efforts relative to species richness, especially by GA airport managers and operations staff, who may have a higher propensity of reporting bird strikes, and by collecting more fieldbased data on avian populations. The results can provide guidance for the development of airport management and personnel training
Spatiotemporal Dynamics in Identification of Aircraft–Bird Strikes
A primary concern for human–wildlife interactions is the potential impacts resulting from wildlife (primarily birds) collisions with aircraft. The identification of species responsible for collisions with aircraft is necessary so that airport management can develop effective strategies to reduce strikes with those species. Of particular importance in developing such strategies is the identification of regional, seasonal, and temporal patterns in collisions with unidentified bird species that may limit the effectiveness of regional habitat management to reduce bird strikes. The authors analyzed 105,529 U.S. civil aviation strike records from 1990 to 2012 in the FAA’s National Wildlife Strike Database to examine patterns of collisions involving unidentified birds. Factors that affected identification were airport certification class, FAA region, mass of struck species, state species richness (if damage was reported), and interactive effects between the last four factors. Identification varied by region and declined with increasing species richness; this identification was greater for general aviation (GA) airports and the mass of struck species, especially when damage was reported. Species identification might be improved by increasing reporting efforts relative to species richness, especially by GA airport managers and operations staff, who may have a higher propensity of reporting bird strikes, and by collecting more fieldbased data on avian populations. The results can provide guidance for the development of airport management and personnel training
Forage or Biofuel: Assessing Native Warm-season Grass Production among Seed Mixes and Harvest Frequencies within a Wildlife Conservation Framework
Native warm-season grasses (NWSG) are gaining merit as biofuel feedstocks for ethanol production with potential for concomitant production of cattle forage and wildlife habitat provision. However, uncertainty continues regarding optimal production approaches for biofuel yield and forage quality within landscapes of competing wildlife conservation objectives. We used a randomized complete block design of 4 treatments to compare vegetation structure, forage and biomass nutrients, and biomass yield between Panicum virgatum (Switchgrass) monocultures and NWSG polycultures harvested once or multiple times near West Point, MS, 2011–2013. Despite taller vegetation and greater biomass in Switchgrass monocultures, NWSG polycultures had greater vegetation structure heterogeneity and plant diversity that could benefit wildlife. However, nutritional content from harvest timings optimal for wildlife conservation (i.e., late dormant season-collected biomass and mid-summer hay samples) demonstrated greater support for biofuel production than quality cattle forage. Future research should consider testing various seed mixes for maximizing biofuel or forage production among multiple site conditions with parallel observations of wildlife use
P06-04. Using referrals from government health centers to expand an HIV discordant couple cohort in Lusaka, Zambia in preparation for vaccine efficacy trials
Breakthrough in marine invertebrate cell culture : Sponge cells divide rapidly in improved nutrient medium
Sponges (Phylum Porifera) are among the oldest Metazoa and considered critical to understanding animal evolution and development. They are also the most prolific source of marine-derived chemicals with pharmaceutical relevance. Cell lines are important tools for research in many disciplines, and have been established for many organisms, including freshwater and terrestrial invertebrates. Despite many efforts over multiple decades, there are still no cell lines for marine invertebrates. In this study, we report a breakthrough: we demonstrate that an amino acid-optimized nutrient medium stimulates rapid cell division in 9 sponge species. The fastest dividing cells doubled in less than 1 hour. Cultures of 3 species were subcultured from 3 to 5 times, with an average of 5.99 population doublings after subculturing, and a lifespan from 21 to 35 days. Our results form the basis for developing marine invertebrate cell models to better understand early animal evolution, determine the role of secondary metabolites, and predict the impact of climate change to coral reef community ecology. Furthermore, sponge cell lines can be used to scale-up production of sponge-derived chemicals for clinical trials and develop new drugs to combat cancer and other diseases.publishedVersio
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