Discounting and the environment should current impacts be weighted differently than impacts harming future generations?

Background: In Life-Cycle Assessment (LCA), decision makers are often faced with tradeoffs between current and future impacts. One typical example is waste incineration, where immediate emissions to the air from the incineration process have to be weighted against future emissions of slag landfills. Long-term impacts are either completely taken into account or they are entirely disregarded in case of a temporal cut-off. Temporal cutoffs are a special case of discounting. Objective: In this paper, discounting is defined as valuing damages differently at different points of time using a positive or negative discount rate. Apart from temporal cut-offs, discounting has rarely been applied in LCA so far. It is the goal of this paper to discuss the concept of discounting and its applicability in the context of LCA. Methods: For this purpose, we first review the arguments for discounting and its principles in economic sciences. Discounting in economics can be motivated by pure time preference, productivity of capital, diminishing marginal utility of consumption, and uncertainties. The nominal discount rate additionally includes changes in the price level. These arguments and their justification are discussed in the context of environmental impacts harming future generations. Results and Discussion: It is concluded that discounting across generations because of pure time preference contradicts fundamental ethical values and should therefore not be applied in LCA. However, it has to be acknowledged that in practice decision makers often use positive discount rates because of pure time preference — either because they might profit from imposing environmental damage on others instead of themselves or because people in the far future are not of immediate concern to them. Discounting because of the productivity of capital assumes a relationship between monetary values and environmental impact. If such a relationship is accepted, discounting could be applied. However, future generations should be compensated for the environmental damage. It is likely that they would demand a higher compensation if the real per capita income increases. As both the compensation and the discount rate are related to economic growth, the overall discount rate might be close to zero. It is shown that the overall discount rate might even be negative considering that the required compensation could increase (even to infinite) if natural assets remain scarce, whereas the utility of consumption diminishes with increasing income. Uncertainties could justify both positive and negative discount rates. Since the relationship between uncertainties and the magnitude of damage is generally not exponential, we recommend to model changes in the magnitude of damage in scenario analysis instead of considering it in discounting (which requires an exponential function of time in the case of a constant discount rate). We investigated the influence of discounting in a case study of heavy metal emissions from slag landfills. It could be shown that even small discount rates of less than 1 % lead to a significant reduction of the impact score, whereas negative discount rates inflate the results. Conclusions and Recommendations: Discounting is only applicable when temporally differentiated data is available. In some cases, such a temporal differentiation is necessary to take sound decisions, especially when long emission periods are involved. An example is the disposal of nuclear or heavy metal-containing waste. In these cases, the results might completely depend on the discount rate. This paper helps to structure arguments and thus to support the decision about whether or not discounting should be applied in an LC

The Biosurfactant β-Aescin: A Review on the Physico-Chemical Properties and Its Interaction with Lipid Model Membranes and Langmuir Monolayers

Geisler R, Dargel C, Hellweg T. The Biosurfactant β-Aescin: A Review on the Physico-Chemical Properties and Its Interaction with Lipid Model Membranes and Langmuir Monolayers. Molecules. 2020;25(1): 117.This review discusses recent progress in physicochemical understanding of the action of the saponin β -aescin (also called β -escin), the biologically active component in the seeds of the horse chestnut tree Aesculus hippocastanum. β -Aescin is used in pharmacological and cosmetic applications showing strong surface activity. In this review, we outline the most important findings describing the behavior of β -aescin in solution (e.g., critical micelle concentration ( cmc ) and micelle shape) and special physicochemical properties of adsorbed β -aescin monolayers at the air–water and oil–water interface. Such monolayers were found to posses very special viscoelastic properties. The presentation of the experimental findings is complemented by discussing recent molecular dynamics simulations. These simulations do not only quantify the predominant interactions in adsorbed monolayers but also highlight the different behavior of neutral and ionized β -aescin molecules. The review concludes on the interaction of β -aescin with phospholipid model membranes in the form of bilayers and Langmuir monolayers. The interaction of β -aescin with lipid bilayers was found to strongly depend on its cmc . At concentrations below the cmc , membrane parameters are modified whereas above the cmc , complete solubilization of the bilayers occurs, depending on lipid phase state and concentration. In the presence of gel-phase phospholipids, discoidal bicelles form; these are tunable in size by composition. The phase behavior of β -aescin with lipid membranes can also be modified by addition of other molecules such as cholesterol or drug molecules. The lipid phase state also determines the penetration rate of β -aescin molecules into lipid monolayers. The strongest interaction was always found in the presence of gel-phase phospholipid molecules

Arguments for an additional long-lived intermediate in the photocycle of the full-length aureochrome 1c receptor: A time-resolved small-angle X-ray scattering study

Bannister S, Böhm E, Zinn T, Hellweg T, Kottke T. Arguments for an additional long-lived intermediate in the photocycle of the full-length aureochrome 1c receptor: A time-resolved small-angle X-ray scattering study. Structural Dynamics. 2019;6(3): 34701.Aureochromes (AUREO) act as blue-light photoreceptors in algae. They consist of a light-, oxygen-, voltage-sensitive (LOV) domain and a DNA-binding basic region/leucine zipper. Illumination of the flavin cofactor in LOV leads to the formation of an adduct, followed by global structural changes. Here, we first applied UV/vis spectroscopy to characterize the photocycle of full-length aureochrome 1c (PtAUREO1c) from the diatom Phaeodactylum tricornutum. With a time constant of 850 s and a quantum yield of 23%, PtAUREO1c reveals a faster recovery time and a much lower sensitivity toward light than PtAUREO1a, pointing to its role as a high light sensor in vivo. UV/vis spectroscopy offers details on the local recovery of the flavin chromophore. However, kinetic information on the global structural recovery of full-length AUREO or any other multidomain LOV protein is missing. This information is essential not least for the photoreceptors' applications as optogenetic devices. Therefore, we established a procedure to apply small-angle X-ray scattering on PtAUREO1c in a time-resolved manner employing an in-house setup. In combination with UV/vis spectroscopy under similar conditions, we revealed a discrepancy between the recovery of the global protein structure and the adduct lifetime. Accordingly, we propose to supplement the photocycle by an intermediate state (I447), which decays with a time constant of about 800 s and prolongs the lifetime of the signaling state

Using consequential LCA and optimization to identify the best uses of biomass resources within the energy sector

In the attempt to mitigate global temperature increase, a strong focus is placed on reducing the greenhouse gas (GHG) emissions from the energy sector, accounting for ca. 65% of the global GHG emissions (Herzog, 2009). Focusing on the Danish energy system as a case study, this study used consequential life-cycle assessment (LCA) and mathematical optimization to highlight optimal uses of the domestic (and eventual imported) biomass resources. This was done by: i) quantifying potentials and characterizing compositions of available biomass, ii) developing consequential LCA scenarios for energy conversion of each individual biomass (including co-products and possible induced effects, e.g. Land-Use Changes LUC) using an ad hoc biochemical model, and iii) optimizing the use of these resources under possible “policy/environmental” targets in the view of minimizing environmental impacts (e.g. global warming) or maximizing the penetration of renewable energy. The solution minimizing impacts from GHG emissions highlighted that domestic agricultural field-residues (e.g. straw/stover), along with the biomass fraction of municipal solid waste, chicken manure, and woody biomass, were optimally used for combustion-CHP (combined heat and power) or heat-only, as to phase-out coal- and oil-fired power and district heating plants. Cow and pig manure should undergo liquid/solid separation for further combustion-CHP of the solid and use on-land of the liquid, or be digested for biogas-CHP production, for the same reason. Subsequent upgrading of biogas to biomethane for use in vehicles was chosen only if a renewable target (as prescribed by the European Union’s Renewable Energy Directive RED) was imposed as a system-constraint, but it did not represent the most beneficial use from a GHG minimization perspective. Residues/by-products from food-industry with high nutritional value (e.g. whey, brewer’s grain, sugar beet residues, potato pulp, and soymeal) should be diverted to the feed sector, as feeding was found to be the optimal solution from a GHG minimization perspective. When allowing the system for producing energy crops, only cultivation of willow and Miscanthus, with further conversion in combustion plant for CHP and heat-only production, was highlighted to be beneficial from a GHG minimization perspective. This, however, was not the case for other environmental objectives, e.g. water footprint due to the induced effect on land, i.e. indirect Land-Use Change (iLUC). In this respect, cultivation of energy crops in Denmark increased feed import thus increasing water depletion-related impacts elsewhere. A similar trade-off was observed when minimizing impacts on N-eutrophication: with respect to this, cultivation of energy crops should be avoided along with biogas production, as this implied additional N load to soil though fertilizers and digestate application on-land, respectively. Allowing import of biomass/biofuels resulted in increased import of wood chips and pellets for direct combustion when minimizing impacts from GHG emissions. A multi-objective solution, aiming at finding an optimal solution across a number of environmental impact categories, was also established based on fuzzy intervals. Such a solution highlighted that improvements compared to the baseline 2013 are possible in all environmental compartments simultaneously. It was found that the GHG emissions could be decreased by 20% compared with the 2013 level without compromising other environmental compartments. Herzog, T., 2009. World Greenhouse Gas Emissions in 2005. WRI Working Paper. World Resources Institute, Washington DC, Unites States. Available online at: http://www.wri.org/publication/navigating-numbers (accessed December 2015)

Mini review: recent advances in biosurfactant-based association colloids–formation of microemulsions

In the context of a more sustainable economy, bio-surfactants become increasingly important, due to their independence of petrol-based chemistry, their usually mild synthesis conditions, and in certain cases their pharmacological activity. We have recently discussed self-assembly studies in binary systems of bio-surfactants of microbial origin, or saponins extracted from plants (Hellweg et al., Frontiers in Soft Matter, 2023, 2). In the present review, we focus on the formation of microemulsions based on these molecules. We review the formation and structure of microemulsion systems formed by oil, water, and biosurfactants, with a particular focus on Quillaja saponins and rhamnolipids

Knowledge graph for manufacturing cost estimation of gear shafts - a case study on the availability of product and manufacturing information in practice

Growing cost pressure forces companies to actively manage their product costs to secure profitability. Here, manufacturing cost estimation within product development estimates manufacturing and material costs. As most products are developed in generations, needed product and manufacturing information can origin from reference system elements (RSE), for example similar components of prior product generations. Problematically, this product and manufacturing information as well as the knowledge of its interrelation is often stored in an unstructured way, document based or at least not machine-readable. This makes manufacturing cost estimation an effortful, time consuming and mainly manual activity with low traceability, where a wide manufacturing knowledge is required. Trends in production, like new manufacturing processes and production systems further increase the need for manufacturing information and knowledge. Knowledge graphs as semantic technologies can improve the findability and reusability of reference system elements and enable automatic information processing. Within this research, cost estimation of research and development of a large automotive supplier was used as research environment. Guided by the model of PGE an ontology for the manufacturing cost estimation domain was developed. Then, a knowledge graph was instantiated based on product and manufacturing information from gear shafts of electric axles. A case study was carried out to evaluate process-specific cycle time calculation as exemplary use case of the knowledge graph. Process-specific cycle times are generally effortful estimated based on detailed manufacturing information and then used together with machine hourly rates to estimate manufacturing costs. Here, the structured and machine-readable manufacturing information of identified reference system elements is extracted from the knowledge graph to reduce the effort, increase the traceability and enable future automation. The case study shows exemplary, how a knowledge graph can support manufacturing cost estimation of gear shafts where product and manufacturing information is automatically identified using reference system elements

Thermoresponsive Microgel Coatings as Versatile Functional Compounds for Novel Cell Manipulation Tools

Uhlig K, Wegener T, Hertle Y, et al. Thermoresponsive Microgel Coatings as Versatile Functional Compounds for Novel Cell Manipulation Tools. POLYMERS. 2018;10(6): 656.For the effective use of live cells in biomedicine as in vitro test systems or in biotechnology, non-invasive cell processing and characterisation are key elements. Thermoresponsive polymer coatings have been demonstrated to be highly beneficial for controlling the interaction of adherent cells through their cultivation support. However, the widespread application of these coatings is hampered by limitations in their adaptability to different cell types and because the full range of applications has not yet been fully explored. In the work presented here, we address these issues by focusing on three different aspects. With regard to the first aspect, by using well-defined laminar flow in a microchannel, a highly controllable and reproducible shear force can be applied to adherent cells. Employing this tool, we demonstrate that cells can be non-invasively detached from a support using a defined shear flow. The second aspect relates to the recent development of simple methods for patterning thermoresponsive coatings. Here, we show how such patterned coatings can be used for improving the handling and reliability of a wound-healing assay. Two pattern geometries are tested using mouse fibroblasts and CHO cells. In terms of the third aspect, the adhesiveness of cells depends on the cell type. Standard thermoresponsive coatings are not functional for all types of cells. By coadsorbing charged nanoparticles and thermoresponsive microgels, it is demonstrated that the adhesion and detachment behaviour of cells on such coatings can be modulated