Transport properties of carbon dioxide in amorphous poly(ethylene furanoate) (PEF) were investigated using complementary pressure-decay sorption and permeation techniques. Detailed measurements for ...PEF at 35 °C indicate a significant, surprisingly large reduction in carbon dioxide permeability of 19× at 1 atm compared to poly(ethylene terephthalate) (PET), despite both an increase in free volume and carbon dioxide solubility of 1.6× for PEF vs PET. The solubility increase for PEF, which originates from greater interaction between carbon dioxide and the polar furan moiety, is offset by a substantial reduction in diffusivity of 31× compared to PET. Such diffusion reduction for PEF, which is 3× greater than the 9.7× reduction in oxygen diffusivity compared to PET, is thought to originate from a hindrance of polymer ring-flipping motions compared to PET. A possible mechanism for the surprising barrier improvement for carbon dioxide in PEF vs PET is explained herein along with a detailed comparison to oxygen and water transport.
Poly(ethylene furanoate) (PEF), the furan-derived analogue to poly(ethylene terephthalate) (PET), can provide a fully biosourced alternative to PET with greatly improved barrier properties and ...attractive thermal and mechanical properties. The improved barrier for PEF compared to PET is unexpected due to the higher free volume of PEF vs PET. Segmental motions related to penetrant diffusion in both polyesters were studied using dynamic mechanical analysis, 13C–CP/MAS solid-state NMR variable contact-time experiments, and centerband-only detection of exchange (CODEX) measurements. Unlike the active phenyl ring-flipping mechanism in PET, furan ring-flipping is greatly suppressed, thereby reducing β relaxation motions and diffusion in PEF due to the energy penalty associated with the nonlinear axis of ring rotation and ring polarity. Preliminary work also shows similar oxygen solubilities for PEF and PET, thereby proving that the drastic permeability reduction results from a decrease in diffusion coefficient caused by a hindrance in furan ring-flipping.
Aquatic environments are often contaminated with complex mixtures of chemicals that may pose a risk to ecosystems and human health. This contamination cannot be addressed with target analysis alone ...but tools are required to reduce this complexity and identify those chemicals that might cause adverse effects. Effect-directed analysis (EDA) is designed to meet this challenge and faces increasing interest in water and sediment quality monitoring. Thus, the present paper summarizes current experience with the EDA approach and the tools required, and provides practical advice on their application. The paper highlights the need for proper problem formulation and gives general advice for study design. As the EDA approach is directed by toxicity, basic principles for the selection of bioassays are given as well as a comprehensive compilation of appropriate assays, including their strengths and weaknesses. A specific focus is given to strategies for sampling, extraction and bioassay dosing since they strongly impact prioritization of toxicants in EDA. Reduction of sample complexity mainly relies on fractionation procedures, which are discussed in this paper, including quality assurance and quality control. Automated combinations of fractionation, biotesting and chemical analysis using so-called hyphenated tools can enhance the throughput and might reduce the risk of artifacts in laboratory work. The key to determining the chemical structures causing effects is analytical toxicant identification. The latest approaches, tools, software and databases for target-, suspect and non-target screening as well as unknown identification are discussed together with analytical and toxicological confirmation approaches. A better understanding of optimal use and combination of EDA tools will help to design efficient and successful toxicant identification studies in the context of quality monitoring in multiply stressed environments.
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•Effect-directed analysis is a powerful tool to support monitoring.•Multiple bioassays on specific and reactive toxicity direct toxicant identification•Combination of extraction and bioassay dosing is key for toxicant identification•Promising tools for LC–MS based toxicant identification are now available
Achieving sustainable agricultural productivity and global food security are two of the biggest challenges of the new millennium. Addressing these challenges requires innovative technologies that can ...uplift global food production, while minimizing collateral environmental damage and preserving the resilience of agroecosystems against a rapidly changing climate. Nanomaterials with the ability to encapsulate and deliver pesticidal active ingredients (AIs) in a responsive (for example, controlled, targeted and synchronized) manner offer new opportunities to increase pesticidal efficacy and efficiency when compared with conventional pesticides. Here, we provide a comprehensive analysis of the key properties of nanopesticides in controlling agricultural pests for crop enhancement compared with their non-nanoscale analogues. Our analysis shows that when compared with non-nanoscale pesticides, the overall efficacy of nanopesticides against target organisms is 31.5% higher, including an 18.9% increased efficacy in field trials. Notably, the toxicity of nanopesticides toward non-target organisms is 43.1% lower, highlighting a decrease in collateral damage to the environment. The premature loss of AIs prior to reaching target organisms is reduced by 41.4%, paired with a 22.1% lower leaching potential of AIs in soils. Nanopesticides also render other benefits, including enhanced foliar adhesion, improved crop yield and quality, and a responsive nanoscale delivery platform of AIs to mitigate various pressing biotic and abiotic stresses (for example, heat, drought and salinity). Nonetheless, the uncertainties associated with the adverse effects of some nanopesticides are not well-understood, requiring further investigations. Overall, our findings show that nanopesticides are potentially more efficient, sustainable and resilient with lower adverse environmental impacts than their conventional analogues. These benefits, if harnessed appropriately, can promote higher crop yields and thus contribute towards sustainable agriculture and global food security.
About 62,000 dead or dying common murres (Uria aalge), the trophically dominant fish-eating seabird of the North Pacific, washed ashore between summer 2015 and spring 2016 on beaches from California ...to Alaska. Most birds were severely emaciated and, so far, no evidence for anything other than starvation was found to explain this mass mortality. Three-quarters of murres were found in the Gulf of Alaska and the remainder along the West Coast. Studies show that only a fraction of birds that die at sea typically wash ashore, and we estimate that total mortality approached 1 million birds. About two-thirds of murres killed were adults, a substantial blow to breeding populations. Additionally, 22 complete reproductive failures were observed at multiple colonies region-wide during (2015) and after (2016-2017) the mass mortality event. Die-offs and breeding failures occur sporadically in murres, but the magnitude, duration and spatial extent of this die-off, associated with multi-colony and multi-year reproductive failures, is unprecedented and astonishing. These events co-occurred with the most powerful marine heatwave on record that persisted through 2014-2016 and created an enormous volume of ocean water (the "Blob") from California to Alaska with temperatures that exceeded average by 2-3 standard deviations. Other studies indicate that this prolonged heatwave reduced phytoplankton biomass and restructured zooplankton communities in favor of lower-calorie species, while it simultaneously increased metabolically driven food demands of ectothermic forage fish. In response, forage fish quality and quantity diminished. Similarly, large ectothermic groundfish were thought to have increased their demand for forage fish, resulting in greater top-predator demands for diminished forage fish resources. We hypothesize that these bottom-up and top-down forces created an "ectothermic vise" on forage species leading to their system-wide scarcity and resulting in mass mortality of murres and many other fish, bird and mammal species in the region during 2014-2017.
Oxygen transport in amorphous poly(ethylene furanoate) (PEF) was studied at various temperatures using complementary permeation and pressure-decay sorption techniques. A significant reduction ...in oxygen permeability of ∼11× was observed at 35 °C for PEF compared to poly(ethylene terephthalate) (PET), and is attributed primarily to reduction in chain segment mobility for PEF resulting from a hindrance of furan ring flipping. A custom-built high accuracy sorption system allowed determination of temperature-dependent so-called dual-mode parameters that have not been reported for oxygen in any polyester. Energetic parameters, i.e. the enthalpy of sorption and activation energies of diffusion and permeation, were measured for oxygen in PEF and discussed in the context of PET and related polyesters. The current work presents the first detailed study of penetrant transport in PEF, which demonstrates the impressive performance enhancements of PEF compared to PET.
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•O2 transport in poly(ethylene furanoate) (PEF) was studied at various temperatures.•Permeation and pressure-decay sorption methods provide complementary data.•PEF exhibits 11× lower O2 permeability vs. poly(ethylene terephthalate) (PET).•Transport energetics are reported for O2 sorption, diffusion and permeation in PEF.•The current work is the first detailed study of penetrant transport in PEF.
Diffusion coefficients for water in amorphous poly(ethylene furanoate) (PEF) and poly(ethylene terephthalate) (PET) were studied at 35 °C over the entire water activity range. PEF exhibits a ∼5× ...reduction in diffusion coefficient averaged over the entire concentration interval compared to PET. Fickian diffusion was observed for water in both polyesters up to ∼0.6 activity, after which the presence of non-Fickian relaxations required treatment using the Berens–Hopfenberg modeling framework. Penetrant plasticization at high activity was found for both PEF and PET, as evidenced by a positive correlation between diffusion coefficient and increasing water concentration. Arrhenius interpretation of diffusion coefficients measured at 15, 25, 35, and 45 °C allowed calculation of the activation energies of diffusion for PEF and PET, which were similar at 47.1 ± 2.8 kJ/mol and 46.4 ± 3.0 kJ/mol, respectively. This study complements prior work pertaining to the equilibrium water sorption properties in both polyesters, and subsequently provides a detailed investigation of the water diffusion process in these materials.
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•Water diffusion properties in PEF and PET were studied at 35 °C from 0 to 1 activity.•Dual-mode diffusion occurred at activity <0.6 and plasticization at activity >0.6.•PEF exhibits a reduction in water diffusion of ∼5× compared to PET.•The effective activation energy of water diffusion is reported for both polyesters.•The current work is the first detailed study of kinetic water sorption in PEF.
Environmental water quality monitoring aims to provide the data required for safeguarding the environment against adverse biological effects from multiple chemical contamination arising from ...anthropogenic diffuse emissions and point sources. Here, we integrate the experience of the international EU-funded project SOLUTIONS to shift the focus of water monitoring from a few legacy chemicals to complex chemical mixtures, and to identify relevant drivers of toxic effects. Monitoring serves a range of purposes, from control of chemical and ecological status compliance to safeguarding specific water uses, such as drinking water abstraction. Various water sampling techniques, chemical target, suspect and non-target analyses as well as an array of in vitro, in vivo and in situ bioanalytical methods were advanced to improve monitoring of water contamination. Major improvements for broader applicability include tailored sampling techniques, screening and identification techniques for a broader and more diverse set of chemicals, higher detection sensitivity, standardized protocols for chemical, toxicological, and ecological assessments combined with systematic evidence evaluation techniques. No single method or combination of methods is able to meet all divergent monitoring purposes. Current monitoring approaches tend to emphasize either targeted exposure or effect detection. Here, we argue that, irrespective of the specific purpose, assessment of monitoring results would benefit substantially from obtaining and linking information on the occurrence of both chemicals and potentially adverse biological effects. In this paper, we specify the information required to: (1) identify relevant contaminants, (2) assess the impact of contamination in aquatic ecosystems, or (3) quantify cause–effect relationships between contaminants and adverse effects. Specific strategies to link chemical and bioanalytical information are outlined for each of these distinct goals. These strategies have been developed and explored using case studies in the Danube and Rhine river basins as well as for rivers of the Iberian Peninsula. Current water quality assessment suffers from biases resulting from differences in approaches and associated uncertainty analyses. While exposure approaches tend to ignore data gaps (i.e., missing contaminants), effect-based approaches penalize data gaps with increased uncertainty factors. This integrated work suggests systematic ways to deal with mixture exposures and combined effects in a more balanced way, and thus provides guidance for future tailored environmental monitoring.
Microscopic organisms are often overlooked in traditional diversity assessments due to the difficulty of identifying them based on morphology. Metabarcoding is a method for rapidly identifying ...organisms where Environmental DNA (eDNA) is used as a template. However, legacy DNA is problematically detected from organisms no longer in the environment during sampling. Environmental RNA (eRNA), which is only produced by living organisms, can also be collected from environmental samples and used for metabarcoding. The aim of this study was to determine differences in community composition and diversity between eRNA and eDNA templates for metabarcoding. Using mesocosms containing field-collected communities from an estuary, RNA and DNA were co-extracted from sediment, libraries were prepared for two loci (18S and COI), and sequenced using an Illumina MiSeq. Results show a higher number of unique sequences detected from eRNA in both markers and higher α-diversity compared to eDNA. Significant differences between eRNA and eDNA for all β-diversity metrics were also detected. This study is the first to demonstrate community differences detected with eRNA compared to eDNA from an estuarine system and illustrates the broad applications of eRNA as a tool for assessing benthic community diversity, particularly for environmental conservation and management applications.
An increase in production of commercial products containing graphene-family nanomaterials (GFNs) has led to concern over their release into the environment. The fate and potential ecotoxicological ...effects of GFNs in the environment are currently unclear, partially due to the limited analytical methods for GFN measurements. In this review, the unique properties of GFNs that are useful for their detection and quantification are discussed. The capacity of several classes of techniques to identify and/or quantify GFNs in different environmental matrices (water, soil, sediment, and organisms), after environmental transformations, and after release from a polymer matrix of a product is evaluated. Extraction and strategies to combine methods for more accurate discrimination of GFNs from environmental interferences as well as from other carbonaceous nanomaterials are recommended. Overall, a comprehensive review of the techniques available to detect and quantify GFNs are systematically presented to inform the state of the science, guide researchers in their selection of the best technique for the system under investigation, and enable further development of GFN metrology in environmental matrices. Two case studies are described to provide practical examples of choosing which techniques to utilize for detection or quantification of GFNs in specific scenarios. Because the available quantitative techniques are somewhat limited, more research is required to distinguish GFNs from other carbonaceous materials and improve the accuracy and detection limits of GFNs at more environmentally relevant concentrations.
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