| 1. |
- Benyahia Erdal, Nejla, et al.
(author)
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Degradation of Cellulose Derivatives in Laboratory, Man-Made, and Natural Environments
- 2022
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In: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 23:7, s. 2713-2729
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Journal article (peer-reviewed)abstract
- Biodegradable polymers complement recyclable materials in battling plastic waste because some products are difficult to recycle and some will end up in the environment either because of their application or due to wear of the products. Natural biopolymers, such as cellulose, are inherently biodegradable, but chemical modification typically required for the obtainment of thermoplastic properties, solubility, or other desired material properties can hinder or even prevent the biodegradation process. This Review summarizes current knowledge on the degradation of common cellulose derivatives in different laboratory, natural, and man-made environments. Depending on the environment, the degradation can be solely biodegradation or a combination of several processes, such as chemical and enzymatic hydrolysis, photodegradation, and oxidation. It is clear that the type of modification and especially the degree of substitution are important factors controlling the degradation process of cellulose derivatives in combination with the degradation environment. The big variation of conditions in different environments is also briefly considered as well as the importance of the proper testing environment, characterization of the degradation process, and confirmation of biodegradability. To ensure full sustainability of the new cellulose derivatives under development, the expected end-of-life scenario, whether material recycling or "biological"recycling, should be included as an important design parameter.
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| 2. |
- Åkesson, Sofia, et al.
(author)
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Characterizing natural degradation of tetrachloroethene (PCE) using a multidisciplinary approach
- 2020
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In: Ambio: a Journal of the Human Environment. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 50, s. 1074-1088
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Journal article (peer-reviewed)abstract
- A site in mid-western Sweden contaminated with chlorinated solvents originating from a previous dry cleaning facility, was investigated using conventional groundwater analysis combined with compound-specific isotope data of carbon, microbial DNA analysis, and geoelectrical tomography techniques. We show the value of this multidisciplinary approach, as the different results supported each interpretation, and show where natural degradation occurs at the site. The zone where natural degradation occurred was identified in the transition between two geological units, where the change in hydraulic conductivity may have facilitated biofilm formation and microbial activity. This observation was confirmed by all methods and the examination of the impact of geological conditions on the biotransformation process was facilitated by the unique combination of the applied methods. There is thus significant benefit from deploying an extended array of methods for these investigations, with the potential to reduce costs involved in remediation of contaminated sediment and groundwater.
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| 3. |
- Hakkarainen, Minna, et al.
(author)
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Environmental degradation of polyethylene
- 2004
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In: LONG-TERM PROPERTIES OF POLYOLEFINS. - Berlin : Springer Berlin Heidelberg. ; , s. 177-199
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Book chapter (peer-reviewed)abstract
- The environmental degradation of polyethylene proceeds by synergistic action of photo- and thermo-oxidative degradation and biological activity. Since biodegradation of commercial high molecular weight polyethylene proceeds slowly, abiotic oxidation is the initial and rate-determining step. Enhanced environmentally degradable polyethylene is prepared by blending with biodegradable additives or photo-initiators or by copolymerisation. One of the key questions for successful development and use of environmentally degradable polymers is to understand the interaction between degradation products and nature. Polymer fragments and degradation products should be environmentally assimilable and should not accumulate or negatively affect the environment. Determination of abiotic and biotic oxidation products is an important step towards establishing the environmental degradation mechanism and environmental impact of the material. More than 200 different degradation products including alkanes, alkenes, ketones, aldehydes, alcohols, carboxylic acid, keto-acids, dicarboxylic acids, lactones and esters have been identified in thermo- and photo-oxidised polyethylene. In biotic environment these abiotic oxidation products and oxidised low molecular weight polymer can be assimilated by microorganisms. In future we will probably see a development of new polyethylenes with tailor-made structures specially designed for environmental degradation through different pathways. Paralleled with the development of these new materials we need to obtain better understanding of the environmental impact of degradable polymers and the interactions between nature and degradation products in a dynamic system.
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| 4. |
- Antonson, Hans, 1963-, et al.
(author)
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Road Salt Damage to Historical Milestones Indicates Adaptation of Winter Roads to Future Climate Change May Damage Arctic Cultural Heritage
- 2021
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In: Climate. - Basel : MDPI. - 2225-1154. ; 9:10
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Journal article (peer-reviewed)abstract
- There is no doubt that anthropogenic global warming is accelerating damage to cultural heritage. Adaptation measures are required to reduce the loss of sites, monuments and remains. However, little research has been directed towards understanding potential impacts of climate adaptation measures in other governmental sectors on cultural heritage. We provide a case study demonstrating that winter road salt, used to reduce ice related accidents, damages historical iron milestones. As the climate warms, road salt use will move north into areas where sites have been protected by contiguous winter snow cover. This will expose Artic/sub-Arctic cultural heritage, including Viking graves and Sami sites, to a new anthropogenic source of damage. Research and planning should therefore include the evaluation of secondary impacts when choosing climate adaptation strategies.
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| 5. |
- Peterson, Jesse, 1983-
(author)
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Excessive Seas : Waste Ecologies of Eutrophication
- 2020
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Doctoral thesis (other academic/artistic)abstract
- This dissertation researches how perspectives in western industrial societies communicate about and give meaning to environmental degradation through case studies on the causes and effects of cultural eutrophication—namely nutrient pollution, algal blooms, and dead zones—in the Baltic Sea. Utilizing this approach, this dissertation addresses the ecological problems of cultural eutrophication in marine ecosystems by exposing normative claims humans make about the Baltic Sea and its contents as well as detailing how seas that exceed human expectations may offer insights into negotiating differing perspectives, discrepancies in power, and ways of being among humans and non-humans in marine environments. In the introduction, the dissertation develops the concept and study of “waste ecology” and then interrogates several concepts related to water, nutrients, algal blooms, and dead zones. Chapter 1 then provides an environmental humanities theoretical and methodological frame which outlines the use of more-than-human ethnography, textual and visual analyses, and storying to assess ways that people value, order, and assign meaning to cultural eutrophication’s consequences in the following five chapters. These chapters explore whether or not the Baltic Sea can die, how nutrients get depicted as pollution, how an “algal perspective” might reframe human relationships to algal blooms, how algal monitoring efforts contribute to a myth that humans can remain separate from nature, and how narratives of environmental collapse depend upon what collapse means and for whom respectively. A final chapter concludes the dissertation, summarizing what the previous chapters might tell us about human relationships to seas besot by cultural eutrophication as well as how a lens of waste ecology might be applied for reorienting these relationships. The dissertation contributes to research and public discussions by providing grounds for critically re-evaluating human relationships to marine environments. It reveals normative material-semiotic assumptions about the Baltic Sea and its ecology and details social and cultural responses to threats that rupture such assumptions and analyses them, showing how these responses attribute varying degrees of value to certain ecological processes, plants and animals, and the sea. It argues for suspending judgment about environmental change while also critically reflecting on efforts that characterize the “environment” as insufficiently capable of handling human activities. Through this research, the dissertation decenters a human exceptionalist tendency to posit that only humans create waste, arguing that waste is co-created with and through (marine) environments and that degradation is not a result of fragility in nature as much as a failure of or lack of imagination in social and cultural organization.
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| 6. |
- Svanström, Sebastian, 1990-, et al.
(author)
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X-ray stability and degradation mechanism of lead halide perovskites and lead halides
- 2021
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In: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 23:21, s. 12479-12489
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Journal article (peer-reviewed)abstract
- Lead halide perovskites have become a leading material in the field of emerging photovoltaics and optoelectronics. Significant progress has been achieved in improving the intrinsic properties and environmental stability of these materials. However, the stability of lead halide perovskites to ionising radiation has not been widely investigated. In this study, we investigated the radiolysis of lead halide perovskites with organic and inorganic cations under X-ray irradiation using synchrotron based hard X-ray photoelectron spectroscopy. We found that fully inorganic perovskites are significantly more stable than those containing organic cations. In general, the degradation occurs through two different, but not mutually exclusive, pathways/mechanisms. One pathway is induced by radiolysis of the lead halide cage into halide salts, halogen gas and metallic lead and appears to be catalysed by defects in the perovskite. The other pathway is induced by the radiolysis of the organic cation which leads to formation of organic degradation products and the collapse of the perovskite structure. In the case of Cs0.17FA0.83PbI3, these reactions result in products with a lead to halide ratio of 1 : 2 and no formation of metallic lead. The radiolysis of the organic cation was shown to be a first order reaction with regards to the FA+ concentration and proportional to the X-ray flux density with a radiolysis rate constant of 1.6 × 10-18 cm2 per photon at 3 keV or 3.3 cm2 mJ-1. These results provide valuable insight for the use of lead halide perovskite based devices in high radiation environments, such as in space environments and X-ray detectors, as well as for investigations of lead halide perovskites using X-ray based techniques.
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| 7. |
- Guo, Y. D., et al.
(author)
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Identification of highly oxygenated organic molecules and their role in aerosol formation in the reaction of limonene with nitrate radical
- 2022
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In: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 22:17, s. 11323-11346
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Journal article (peer-reviewed)abstract
- Nighttime NO3-initiated oxidation of biogenic volatile organic compounds (BVOCs) such as monoterpenes is important for the atmospheric formation and growth of secondary organic aerosol (SOA), which has significant impact on climate, air quality, and human health. In such SOA formation and growth, highly oxygenated organic molecules (HOM) may be crucial, but their formation pathways and role in aerosol formation have yet to be clarified. Among monoterpenes, limonene is of particular interest for its high emission globally and high SOA yield. In this work, HOM formation in the reaction of limonene with nitrate radical (NO3) was investigated in the SAPHIR chamber (Simulation of Atmospheric PHotochemistry In a large Reaction chamber). About 280 HOM products were identified, grouped into 19 monomer families, 11 dimer families, and 3 trimer families. Both closed-shell products and open-shell peroxy radicals (RO2 center dot) 2 were observed, and many of them have not been reported previously. Monomers and dimers accounted for 47% and 47% of HOM concentrations, respectively, with trimers making up the remaining 6 %. In the most abundant monomer families, C10H15-17NO6-14, carbonyl products outnumbered hydroxyl products, indicating the importance of RO2 center dot termination by unimolecular dissociation. Both RO2 center dot autoxidation and alkoxy-peroxy pathways were found to be important processes leading to HOM. Time-dependent concentration profiles of monomer products containing nitrogen showed mainly second-generation formation patterns. Dimers were likely formed via the accretion reaction of two monomer RO2 center dot , and HOM-trimers via the accretion reaction between monomer RO2 center dot and dimer RO2 center dot. Trimers are suggested to play an important role in new particle formation (NPF) observed in our experiment. A HOM yield of 1.5%(+1.7%)(-0.7%) was estimated considering only first-generation products. SOA mass growth could be reasonably explained by HOM condensation on particles assuming irreversible uptake of ultra-low volatility organic compounds (ULVOCs), extremely low volatility organic compounds (ELVOCs), and low volatility organic compounds (LVOCs). This work provides evidence for the important role of HOM formed via the limonene +NO3 reaction in NPF and growth of SOA particles.
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| 8. |
- Pemunta, Ngambouk Vitalis, Dr, 1973-
(author)
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The logic of benevolent capitalism : the duplicity of Sithe Global Sustainable Oils Cameroon land grab and deforestation scheme as sustainable investment
- 2018
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In: International Journal of Global Environmental Issues. - : InderScience Publishers. - 1466-6650 .- 1741-5136. ; 17:1, s. 80-109
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Journal article (peer-reviewed)abstract
- This ethnographic study documents the concurrent debates pitting neoliberal ideology promoting economic growth and the generation of employment opportunities championed by the agro-industrial giant Herakles Farms, alongside the World Bank and the government of Cameroon - inherent in the establishment of a 73,086 ha oil palm plantation in Southwest Cameroon against the need for sustainable environment advocated for by local communities, NGOs and their transnational allies. Claims of benevolent capitalism are at odds with the perception and experiences of home loss and environmental degradation orchestrated by this project. The dissonance between the discourses and claims of benevolent capitalism with the perception and experiences of home loss and environmental degradation orchestrated by this project demonstrates that the neoliberal discourse of capitalist benevolence is a self-interested discourse that benefits the powerful at the expense of the subaltern. Local people should be empowered to negotiate with multinational corporations, laws recognising customary land rights instituted and implemented.
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| 9. |
- Benavente Araoz, Fabian Andres, 1985-, et al.
(author)
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Effect of Partial Cycling of NCA/Graphite Cylindrical Cells in Different SOC Intervals
- 2020
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In: Journal of the Electrochemical Society. - : Institute of Physics Publishing. - 0013-4651 .- 1945-7111. ; 167:4
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Journal article (peer-reviewed)abstract
- A quasi-realistic aging test of NCA/graphite lithium-ion 18650 cylindrical cells is performed during a long-term low c-rate cycling and using a new protocol for testing and studying the aging. This to emulate a characteristic charge/discharge profile of off-grid PV-battery systems. The cells were partially cycled at four different cut-off voltages and two state of charge ranges (ΔSOC) for 1000 and 700 cycles over 24 months. Differential voltage analysis shows that a combination of loss of active material (LAM) and loss of lithium inventory (LLI) are the causes of capacity loss. Cells cycled with high cut-off voltages and wide ΔSOC (20% to 95%) were severely affected by material degradation and electrode shift. High cut-off voltage and narrow ΔSOC (65% to 95%) caused greater electrode degradation but negligible cell unbalance. Cell impedance is observed to increase in both cells. Cells cycled with middle to low cut-off voltages and narrow ΔSOC (35%-65% and 20% to 50%) had comparable degradation rates to calendar-aged cells. Cycling NCA/graphite cells with low c-rate and high cut-off voltages will degrade the electrode in the same way high c-rate would do. However, low c-rate at low and middle cut-off voltages greatly decrease cell degradation compared to similar conditions at middle to high c-rate, therefore increasing battery lifetime. © 2020 The Author(s).
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| 10. |
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Producing nature and poverty in Africa
- 2000
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Editorial collection (other academic/artistic)abstract
- Development donors have supported thousands of environmental initiatives in Africa over the past quarter century. The contributors to this provocative new collection of essays assess these projects and conclude that environmental programmes constitute one of the major forms of foreign and state intervention in contemporary African affairs. Drawing on case study material from eight countries, the authors demonstrate clearly that environmental programmes themselves often have direct and far-reaching consequences for the distribution of wealth and poverty on the continent.Individual essays in the collection theorise specific forms of environmental intervention; the degree of historical discontinuity that exists between contemporary and past environmental policies and practices; the effect environmental programmes have had on localised systems of knowledge and value regimes; the strategies of accumulation that have been spun out of heavy donor and state investment in environmental programmes; and the numerous social, cultural and political-economic dislocations these initiatives have produced in African environments all across the continent.
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