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The emergence of metagenomics-based approaches in biology has overcome historical culture-based biases in microbiological studies. This has also enabled a more comprehensive assessment of the microbial ecology of environmental samples. The subsequent development of next-generation sequencing technologies, able to produce hundreds of millions of sequences at improved cost and speed, necessitated a computational shift from user-supervised alignment and analysis pipelines, that were used previously for vector-based metagenomic studies that relied on Sanger sequencing. Current computational advances have expanded the scope of microbial biogeography studies and offered novel insights into microbial responses to environmental variation and anthropogenic inputs into ecosystems. However, new biostatistical and computational approaches are required to handle the large volume and complexity of these new multivariate datasets. While this has allowed more complete characterization of taxonomic, phylogenetic and functional microbial diversity, these tools are still limited by methodological biases, incomplete databases, and the high cost of fully characterizing environmental biodiversity. This review addresses the evolution of methods to monitor surface waters and characterize environmental samples through the recent computational advances in metagenomics, with an emphasis on the study of surface waters. These new methods have provided an abundance of opportunities to expand our understanding of the interaction between microbial communities and public health. Specifically, they have allowed for comprehensive monitoring of bacterial communities in surface waters for changes in community structure associated with faecal contamination and the presence of human pathogens, rather than relying on only a few indicator bacteria to direct public health concerns.
Recent studies suggest that sand can serve as a vehicle for exposure of humans to pathogens at beach sites, resulting in increased health risks. Sampling for microorganisms in sand should therefore be considered for inclusion in regulatory programmes aimed at protecting recreational beach users from infectious disease. Here, we review the literature on pathogen levels in beach sand, and their potential for affecting human health. In an effort to provide specific recommendations for sand sampling programmes, we outline published guidelines for beach monitoring programmes, which are currently focused exclusively on measuring microbial levels in water. We also provide background on spatial distribution and temporal characteristics of microbes in sand, as these factors influence sampling programmes. First steps toward establishing a sand sampling programme include identifying appropriate beach sites and use of initial sanitary assessments to refine site selection. A tiered approach is recommended for monitoring. This approach would include the analysis of samples from many sites for faecal indicator organisms and other conventional analytes, while testing for specific pathogens and unconventional indicators is reserved for high-risk sites. Given the diversity of microbes found in sand, studies are urgently needed to identify the most significant aetiological agent of disease and to relate microbial measurements in sand to human health risk.
A melt-spinnable precursor of aluminum nitride fibers derived from triethylaluminum and ammonia contains AlNH, AlNH2 groups, and a small number of AlN units characteristic of aluminum nitride. The molecular weight of a spinnable composition is 070, corresponding to an average molecular weight of 13 organoaluminum groups. Ammonia, a curing agent for the fibers, accelerates elimination of ethane from the material, and decreases its solubility in toluene.
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