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- Hynynen, Jonna, 1987, et al.
(författare)
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'Lignin and extractives first' conversion of lignocellulosic residual streams using UV light from LEDs
- 2021
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Ingår i: Green Chemistry. - : Royal Society of Chemistry (RSC). - 1463-9262 .- 1463-9270. ; 23, s. 8251-8259
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Tidskriftsartikel (refereegranskat)abstract
- Lignocellulosic biomass, especially lignin and extractives, has the potential to substitute fossil precursors in the chemical industry. The conversion of lignin has been intensively researched, but challenges remain as high temperatures and increased pressure are commonly used, which is not energy efficient. Lignin and wood extractives bear chromophoric groups that can absorb light in the ultraviolet (UV) region, which enables photochemical reactions. Ultraviolet light emitting diodes (UV-LEDs) are an emerging technology; they are cheap, versatile, and energy-efficient compared to existing mercury lamps. UV-LEDs were used in this study as a proof of concept for the valorisation of a lignocellulosic residual stream from the pulp and paper industry, sawdust. In a process at ambient temperature and pressure and without the use of a catalyst, we have shown that lignin and extractives can be valorised using light from UV-LEDs. Simplified lignin model compounds were used to pinpoint chemical reactions during irradiation, and to ease the analysis of the sawdust samples. The rate of conversion upon irradiation of the model compounds was found to be 0.7-2.3 g L-1 h(-1), depending on the concentration of the starting compounds.
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- Takács, Károly, PhD, 1973-, et al.
(författare)
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Networks of reliable reputations and cooperation : a review
- 2021
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Ingår i: Philosophical Transactions of the Royal Society of London. Biological Sciences. - : Royal Society of London. - 0962-8436 .- 1471-2970. ; 376:1838
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Tidskriftsartikel (refereegranskat)abstract
- Reputation has been shown to provide an informal solution to the problem of cooperation in human societies. After reviewing models that connect reputations and cooperation, we address how reputation results from information exchange embedded in a social network that changes endogenously itself. Theoretical studies highlight that network topologies have different effects on the extent of cooperation, since they can foster or hinder the flow of reputational information. Subsequently, we review models and empirical studies that intend to grasp the coevolution of reputations, cooperation and social networks. We identify open questions in the literature concerning how networks affect the accuracy of reputations, the honesty of shared information and the spread of reputational information. Certain network topologies may facilitate biased beliefs and intergroup competition or in-group identity formation that could lead to high cooperation within but conflicts between different subgroups of a network. Our review covers theoretical, experimental and field studies across various disciplines that target these questions and could explain how the dynamics of interactions and reputations help or prevent the establishment and sustainability of cooperation in small- and large-scale societies.
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