Self-ignition of tetrafluoroethylene induced by rapid valve opening in small diameter pipes

This work investigates the ignition of tetrafluoroethylene induced by the adiabatic compression that can arise by activating a high speed valve separating two portions of a pipeline with a high pressure difference. In the tests performed the high pressure zone contained tetrafluoroethylene at pressures between 15 and 30 bar. For the low pressure zone, experiments with nitrogen, air and tetrafluoroethylene were carried out. The pressure range in the low pressure zone was comprised between 0.05 and 1 bar. The pipe diameters analyzed were 15 and 20 mm. For the analyzed geometries, special conditions were required in order to reach reproducible ignitions, namely air at temperatures of at least 105 °C had to be present in the compression pipe. Furthermore, a minimum length of the compression pipe had to be used. The current work describes the experimental setup employed for the tests and discusses the achieved results. Numerical simulations were performed in order to clarify unexpected findings.     

Characterization of Drought in the South Atlantic,United States

Drought has been less extensively characterized in the humid South Atlantic compared to the arid western United States. Our objective was to characterize drought in the South Atlantic and to understand whether drought has become more severe in this region over time. Here we used monthly streamflow to characterize hydrological drought. Hydrological drought occurred when streamflow fell below the 20th percentile over three consecutive months and terminated once streamflow remained above the 20th percentile for three consecutive months. We characterized the frequency, duration, magnitude, and severity of events using the above definition. Significant changes in drought characteristics were tested with Mann‐Kendall over three periods: 1930‐2010, 1930‐1969, and 1970‐2010. We show that 71% of drought events were shorter than six months, while 7% were multiyear events. There was little evidence of trends in drought characteristics to support the claim of drought becoming more severe in the South Atlantic over the 20th Century. The one exception was a significant increase in the joint probability of nearby basins being simultaneously in drought conditions in the southern portion of the study area from 1970 to 2010. While drought characteristics have changed little through time, decreasing average streamflow in non drought periods coupled with increasing water demand provide the context within which recent multiyear drought events have produced significant stress on existing water infrastructure.     

Working on the sustainability of local communities with a “community-engaged” research methodology

Abstract

The Globalism Institute at Royal Melbourne Institute of Technology (RMIT) University in Melbourne is conducting research on local responses to globalisation across 10 local communities in seven different countries. The project's “community-engaged research methodology” was developed first in the Hamilton region in southwest Victoria, where staff from the university have been working in community partnerships for nearly 20 years. This research methodology differs from action research in that it sustains a clear distinction between the knowledge and skills of “outside” researchers and the hard-won local knowledge of community members. It is based on respectful dialogue and a clear commitment to maintain relationships for a matter of years rather than weeks. It involves the creation of “spaces for engagement” that can lead to multiple, sometimes unexpected, outcomes. It integrates a range of research methods (including surveys, story collection, strategic conversations, photo-narrative techniques, and research journals) that generate rich data to be used (subject to consent) by both community-based and university-based researchers. The research methods are linked to forms of analysis that relate local experiences to broader social processes. Community-engaged research takes time and patience but it can ensure good feedback and support mechanisms, good-quality data, locally relevant research outcomes and a process that can be convivial for all involved.     

Differences in Global Scientific Production Between New mRNA and Conventional Vaccines Against COVID-19

Environmental Science and Pollution Research - The search for effective vaccines to stop the COVID-19 pandemic has led to an unprecedented amount of global scientific production and activity. This...     

Comparison of different salt solutions for density separation of conventional and biodegradable microplastic from solid sample matrices

Environmental Science and Pollution Research - Microplastics are the new emerging pollutants ubiquitously detectable in aquatic and terrestrial ecosystems. Fate and behavior, as well as...     

Aquatic toxicity of glyphosate-based formulations: comparison between different organisms and the effects of environmental factors

Glyphosate-based herbicides (e.g. Roundup) are extensively used in the aquatic environment, but there is a paucity of data on the toxicity of the formulated products and the influences by environmental factors. In this study, the acute toxicity of technical-grade glyphosate acid, isopropylamine (IPA) salt of glyphosate, Roundup and its surfactant polyoxyethylene amine (POEA) to Microtox bacterium (Vibrio fischeri), microalgae (Selenastrum capricornutum and Skeletonema costatum), protozoa (Tetrahymena pyriformis and Euplotes vannus) and crustaceans (Ceriodaphnia dubia and Acartia tonsa) was examined and the relative toxicity contributions of POEA to Roundup were calculated. The effects of four environmental factors (temperature, pH, suspended sediment and algal food concentrations) on the acute toxicity of Roundup to C. dubia were also examined. Generally, the toxicity order of the chemicals was: POEA>Roundup>glyphosate acid>IPA salt of glyphosate, while the toxicity of glyphosate acid was mainly due to its high acidity. Microtox bacterium and protozoa had similar sensitivities towards Roundup toxicity (i.e. IC50 from 23.5 to 29.5 mg AE/l). In contrast, microalgae and crustaceans were 4-5 folds more sensitive to Roundup toxicity than bacteria and protozoa. Except photosynthetic microalgae, POEA accounted for more than 86% of Roundup toxicity and the toxicity contribution of POEA was shown to be species-dependent. Increase in pH (6-9) and increase of suspended sediment concentration (0-200 mg/l) significantly increased the toxicity of Roundup to C. dubia, but there were no significant effects due to temperature change and food addition.     

Age-size plasticity for reproduction in monocarpic plants

Empirical and theoretical investigations of monocarpy have usually addressed the question of minimum or threshold sizes for reproduction. However, the range of flowering sizes observed in many monocarpic species is extraordinarily large (well beyond what can be called a "threshold"), and the sizes of flowering and nonflowering plants may overlap greatly. We attempt to explain these reproductive patterns in terms of optimal reaction norms predicted by simple deterministic life history models. We assume that individuals differ in their growth trajectories due to the heterogeneous quality of microsites and ask how the optimal age and size at flowering varies with environmental variation in growth and for different assumptions about fecundity and mortality. Under two very different growth functions (one with no age- or size-related decline in growth rate and another with such a decline as size approaches an asymptote), the optimal reaction norms imply considerable plasticity for size at reproduction, particularly when poor growth is associated with higher mortality or lower asymptotic size. Deterministic models such as these may be more applicable to long-lived than to short-lived monocarps, because fitness potential should be less affected by stochastic variability in yearly growing condition in the former than in the latter. We consider the case of a tropical monocarpic and masting tree species, Cerberiopsis candelabra (Apocynaceae), and show that our model results can account for wide ranges of reproductive size and overlap in size of flowering and nonflowering plants, in accord with observation. We suggest that empirical attention to norms of reaction across growth environments will be a more profitable approach than investigation of size thresholds per se.     

Estrogenic and dioxin-like compounds in sediment from Zierikzee harbour identified with CALUX assay-directed fractionation combined with one and two dimensional gas chromatography analyses

The identity of compounds responsible for estrogenic and dioxin-like activities in sediment from the harbour of the small town Zierikzee in Zeeland, The Netherlands, was investigated using a bioassay directed fractionation approach with the in vitro estrogen and dioxin responsive reporter gene assays ER- and DR-CALUX. For identification of compounds exhibiting activity in the bioassays, either one or two-dimensional GC in combination with quadrupole (MSD), ion trap (ITD) or time-of-flight mass spectrometric detection (ToF-MS) was used, depending on the biological and chemical characteristics and the complexity of the fractions. The natural estrogenic hormone 17-β-estradiol and its metabolite estrone were identified with GC–ITD as the main contributors to the estrogenic activity. After successive rounds of fractionation, the dioxin-like activity could be explained by the presence of various polycyclic aromatic hydrocarbons identified with GC–MSD and two-dimensional comprehensive GC × GC–ToF-MS. Some estrogenic activity of a relatively non-polar nature remained unidentified.     

Fundamental trade-offs generating the worldwide leaf economics spectrum

Recent work has identified a worldwide "economic" spectrum of correlated leaf traits that affects global patterns of nutrient cycling and primary productivity and that is used to calibrate vegetation-climate models. The correlation patterns are displayed by species from the arctic to the tropics and are largely independent of growth form or phylogeny. This generality suggests that unidentified fundamental constraints control the return of photosynthates on investments of nutrients and dry mass in leaves. Using novel graph theoretic methods and structural equation modeling, we show that the relationships among these variables can best be explained by assuming (1) a necessary trade-off between allocation to structural tissues versus liquid phase processes and (2) an evolutionary tradeoff between leaf photosynthetic rates, construction costs, and leaf longevity.     

No-take marine reserves and reef fisheries management in the Philippines: a new people power revolution

The marine-conservation and reef fisheries-management program that exists today in the Philippines had humble beginnings in the 1970s at Sumilon and Apo islands. These islands have produced some of the best evidence available that no-take reserves, protected and managed by local communities, can play a key role in biodiversity conservation and fisheries management. Perhaps more importantly, they served as models for an extraordinary expansion of no-take reserves nationally in the Philippines in the past 2 decades. This expansion contributed substantially to a major shift in national policy of management of marine resources. This policy shift partially devolved responsibility from a centralized government bureaucracy to local governments and local communities. Local governments now comanage, along with the national government, marine resources out to 15 km from the coast. Giving some responsibility for management of marine resources to coastal people dependent upon those resources represents, in a very real sense, another "people power revolution" in the Philippines.