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End date: 2024 × Start date: 2020 × Type: article × Publisher: Amsterdam : Elsevier ×

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    Polymeric monolithic materials: Syntheses, properties, functionalization and applications
    (Amsterdam : Elsevier, 2007) Buchmeiser, M.R.
    The synthetic particularities for the synthesis of polymer-based monolithic materials are summarized. In this context, monoliths prepared via thermal-, UV- or electron-beam triggered free radical polymerization, controlled TEMPO-mediated radical polymerization, polyaddition, polycondensation as well as living ring-opening metathesis polymerization (ROMP) will be covered. Particular attention is devoted to the aspects of controlling pore sizes, pore volumes and pore size distributions as well as functionalization of these supports. Finally, selected, recent applications in separation science, (bio-) catalysis and chip technology will be summarized. © 2007 Elsevier Ltd. All rights reserved.
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    Multiproxy approach to the reconstruction of soil denudation events and the disappearance of Luvisols in the loess landscape of south-western Poland
    (Amsterdam : Elsevier, 2022) Loba, Aleksandra; Zhang, Junjie; Tsukamoto, Sumiko; Kasprzak, Marek; Beata Kowalska, Joanna; Frechen, Manfred; Waroszewski, Jarosław
    Loess landscapes are highly susceptible to soil redeposition processes and thus may provide detailed insights into the record of denudation processes. Using optically stimulated luminescence dating and the soil micromorphology of 12 soil profiles, we reconstructed a complete record of denudation processes in south-western Poland. The first episode of soil redeposition took place around 9.1 ka. The denudation events that followed were attributed to the Neolithic (6.4 ± 0.3 ka), early Bronze Age (3.8 ± 0.2 ka), early and late Middle Ages (1.5 ± 0.1 ka and 0.7 ± 0.03 ka, respectively) and early Modern (0.4 ± 0.02 ka). As a consequence of the denudation processes, the soil cover in the studied area had been strongly reshaped. The predominant Luvisols had experienced progressive erosion processes that led first to a significant shallowing of the eluvial and argic horizons (truncated Luvisol) and, after some time, to their complete removal. Further thinning of the loess mantles had exposed geological substrates with very weak pedogenic alternations, thus pushing their transformation towards Regosol types. Similarly, Regosols occurred in toeslopes where freshly eroded material had been deposited, and where diagnostic horizons had not yet developed. Modern soil erosion rates in the studied loess area have considerably increased, and it is estimated that the Luvisol status may be completely transformed within approximately 80–300 years, if not sooner, due to progressive climate change.
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    Low temperature thermoluminescence of β-Ga2O3 scintillator
    (Amsterdam : Elsevier, 2022) Witkowski, Marcin E.; Drozdowski, Konrad J.; Makowski, Michał; Drozdowski, Winicjusz; Wojtowicz, Andrzej J.; Irmscher, Klaus; Schewski, Robert; Galazka, Zbigniew
    Low temperature thermoluminescence of β-Ga2O3, β-Ga2O3:Al and β-Ga2O3:Ce has been investigated. Glow curves have been analyzed quantitatively using a rate equations model in order to determine the traps parameters, such as activation energies, capture cross-sections and probabilities of recombination and retrapping.
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    Optimal carbon taxation and horizontal equity: A welfare-theoretic approach with application to German household data
    (Amsterdam : Elsevier, 2022) Hänsel, Martin C.; Franks, Max; Kalkuhl, Matthias; Edenhofer, Ottmar
    We develop a model of optimal taxation and redistribution under an ambitious climate target. We take into account vertical income differences, but also explicitly capture horizontal equity concerns by considering heterogeneous energy efficiencies. By deriving first- and second-best rules for policy instruments including carbon and labor taxes, transfers and energy subsidies, we investigate analytically how vertical and horizontal inequality is considered in the welfare maximizing tax structure. We calibrate the model to German household data and a 30 percent emission reduction goal and show that redistribution of carbon tax revenues via household-specific transfers is the first-best policy. Under plausible assumptions on inequality aversion, transfers to energy-intensive households should be about five times higher than transfers to energy-efficient households. Equal per-capita transfers do not require to observe households’ efficiency type, but increase equity-weighted mitigation costs by around 5 percent compared to the first-best. Mitigation costs increase by less, if the government can implement a uniform clean energy subsidy or household-specific tax-subsidy schemes on energy consumption and labor income that target heterogeneous energy efficiencies. Horizontal equity concerns may therefore constitute a new second-best rationale for clean energy policies or differentiated energy taxes.
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    Automated tangential-flow diafiltration device
    (Amsterdam : Elsevier, 2021) Lüken, Arne; Bruckhaus, Maike; Kosfeld, Udo; Emondts, Meike; Wessling, Matthias
    Tangential flow filtration (TFF) is a chemical unit operation used to purify and concentrate liquid suspensions of colloids, proteins, or cells. The solution flows tangentially across a membrane, such that a selective part of the fluid permeates the membrane while the filtrated matter is retained, increasing its concentration. TFF is a mild mechanical purification method that does not interact chemically with the filtrate. It is applied in sensitive separation tasks in protein chemistry, microbiology, or immunology. It is a fast alternative for dialysis applications, also applicable in the field of colloid purification. However, the costs of automated lab-scale devices (30,000 €) and the consumable membrane modules (100–600 €) make TFF currently hardly accessible for lab-scale polymer researchers. Therefore, we built a low-cost TFF system (2400 €) partly automated by an Arduino microcontroller and optimized for diafiltration buffer exchange and concentration processes in soft matter colloid research. We use medical hemodialysis membrane modules that only cost a share (20–50 €) of alternative TFF modules, and we demonstrate the functionality of the system for an exemplary colloidal microgel purification process.
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    First-Order Methods for Convex Optimization
    (Amsterdam : Elsevier, 2021) Dvurechensky, Pavel; Shtern, Shimrit; Staudigl, Mathias
    First-order methods for solving convex optimization problems have been at the forefront of mathematical optimization in the last 20 years. The rapid development of this important class of algorithms is motivated by the success stories reported in various applications, including most importantly machine learning, signal processing, imaging and control theory. First-order methods have the potential to provide low accuracy solutions at low computational complexity which makes them an attractive set of tools in large-scale optimization problems. In this survey, we cover a number of key developments in gradient-based optimization methods. This includes non-Euclidean extensions of the classical proximal gradient method, and its accelerated versions. Additionally we survey recent developments within the class of projection-free methods, and proximal versions of primal-dual schemes. We give complete proofs for various key results, and highlight the unifying aspects of several optimization algorithms.
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    Investigation of changes in crystalline and amorphous structure during deformation of nano-reinforced semi-crystalline polymers by space-resolved synchrotron saxs and waxs
    (Amsterdam : Elsevier, 2009) Schneider, K.; Schone, A.; Jun, T.-S.; Korsunsky, A.M.
    Complex structural changes occur in semi-crystalline polymers during deformation. In (nano-)filled systems the situation becomes even more complicated, since not only phase changes may take place, but also local (interfacial) failure between phases may occur. To help identify specific processes taking place within these systems, simultaneous small- and wide-angle X-ray scattering (SAXS/WAXS) measurements were performed using synchrotron radiation during in situ deformation. Using a highly focused beam, spatially resolved local information can be extracted by scanning the beam across the deformed/damaged region within the sample. The characteristic changes in the different phases are presented and discussed. While the study of WAXS patterns gives insight into the orientation and dimensions of the crystallites, SAXS provides information about the mutual arrangement of phases and the interfacial failure phenomena. Based on the analysis of the results obtained in our experiments it will be shown that the first changes in the crystalline phase appear long before macroscopic yielding of the sample is reached, i.e. the onset of irreversible deformation takes place. In the post-yield regime radical changes are observed in both the long- and short-range structures. It is concluded that the presence of nano-fillers exerts a strong influence on the establishment of microcrystalline structure, and hence also on the deformation behaviour at the microscopic scale.
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    Articulating the effect of food systems innovation on the Sustainable Development Goals
    (Amsterdam : Elsevier, 2021) Herrero, Mario; Thornton, Philip K.; Mason-D'Croz, Daniel; Palmer, Jeda; Bodirsky, Benjamin L.; Pradhan, Prajal; Barrett, Christopher B.; Benton, Tim G.; Hall, Andrew; Pikaar, Ilje; Bogard, Jessica R.; Bonnett, Graham D.; Bryan, Brett A.; Campbell, Bruce M.; Christensen, Svend; Clark, Michael; Fanzo, Jessica; Godde, Cecile M.; Jarvis, Andy; Loboguerrero, Ana Maria; Mathys, Alexander; McIntyre, C. Lynne; Naylor, Rosamond L.; Nelson, Rebecca; Obersteiner, Michael; Parodi, Alejandro; Popp, Alexander; Ricketts, Katie; Smith, Pete; Valin, Hugo; Vermeulen, Sonja J.; Vervoort, Joost; van Wijk, Mark; van Zanten, Hannah HE; West, Paul C.; Wood, Stephen A.; Rockström, Johan
    Food system innovations will be instrumental to achieving multiple Sustainable Development Goals (SDGs). However, major innovation breakthroughs can trigger profound and disruptive changes, leading to simultaneous and interlinked reconfigurations of multiple parts of the global food system. The emergence of new technologies or social solutions, therefore, have very different impact profiles, with favourable consequences for some SDGs and unintended adverse side-effects for others. Stand-alone innovations seldom achieve positive outcomes over multiple sustainability dimensions. Instead, they should be embedded as part of systemic changes that facilitate the implementation of the SDGs. Emerging trade-offs need to be intentionally addressed to achieve true sustainability, particularly those involving social aspects like inequality in its many forms, social justice, and strong institutions, which remain challenging. Trade-offs with undesirable consequences are manageable through the development of well planned transition pathways, careful monitoring of key indicators, and through the implementation of transparent science targets at the local level.
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    Integrating Life Cycle and Impact Assessments to Map Food's Cumulative Environmental Footprint
    (Amsterdam : Elsevier, 2020) Kuempel, Caitlin D.; Frazier, Melanie; Nash, Kirsty L.; Jacobsen, Nis Sand; Williams, David R.; Blanchard, Julia L.; Cottrell, Richard S.; McIntyre, Peter B.; Moran, Daniel; Bouwman, Lex; Froehlich, Halley E.; Gephart, Jessica A.; Metian, Marc; Többen, Johannes; Halpern, Benjamin S.
    Producing food exerts pressures on the environment. Understanding the location and magnitude of food production is key to reducing the impacts of these pressures on nature and people. In this Perspective, Kuempel et al. outline an approach for integrating life cycle assessment and cumulative impact mapping data and methodologies to map the cumulative environmental pressure of food systems. The approach enables quantification of current and potential future environmental pressures, which are needed to reduce the net impact of feeding humanity. © 2020 The AuthorsFeeding a growing, increasingly affluent population while limiting environmental pressures of food production is a central challenge for society. Understanding the location and magnitude of food production is key to addressing this challenge because pressures vary substantially across food production types. Applying data and models from life cycle assessment with the methodologies for mapping cumulative environmental impacts of human activities (hereafter cumulative impact mapping) provides a powerful approach to spatially map the cumulative environmental pressure of food production in a way that is consistent and comprehensive across food types. However, these methodologies have yet to be combined. By synthesizing life cycle assessment and cumulative impact mapping methodologies, we provide guidance for comprehensively and cumulatively mapping the environmental pressures (e.g., greenhouse gas emissions, spatial occupancy, and freshwater use) associated with food production systems. This spatial approach enables quantification of current and potential future environmental pressures, which is needed for decision makers to create more sustainable food policies and practices. © 2020 The Authors
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    Energy system changes in 1.5 °C, well below 2 °C and 2 °C scenarios
    (Amsterdam : Elsevier, 2019) Gambhir, Ajay; Rogelj, Joeri; Luderer, Gunnar; Few, Sheridan; Napp, Tamaryn
    Meeting the Paris Agreement's goal to limit global warming to well below 2 °C and pursuing efforts towards 1.5 °C is likely to require more rapid and fundamental energy system changes than the previously-agreed 2 °C target. Here we assess over 200 integrated assessment model scenarios which achieve 2 °C and well-below 2 °C targets, drawn from the IPCC's fifth assessment report database combined with a set of 1.5 °C scenarios produced in recent years. We specifically assess differences in a range of near-term indicators describing CO2 emissions reductions pathways, changes in primary energy and final energy across the economy's major sectors, in addition to more detailed metrics around the use of carbon capture and storage (CCS), negative emissions, low-carbon electricity and hydrogen. © 2018 The Authors