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- Andersson, Annica, et al.
(författare)
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Paths to a sustainable food sector guided by LCA – exemplified by pork production
- 2014
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- To describe a more sustainable food sector, a supply chain approach is needed. Changing supply chains inevitably means that a range of attributes of the product and its system will change. This project will take on this challenge and deliver detailed descriptions of supply chains of six commodities from a Swedish region in 2012; Milk, cheese, beef, pork, chicken and bread. The set-up of the project was that experts on production along the supply chain design environmentally improved systems. The next step was to challenge the improvements considering their possible consequences on products and systems from different perspectives: food safety, sensory qualities, animal welfare, and consumer appreciation and (only for primary production) costs. The final supply chains were quantified by life cycle assessment (LCA), and they were again assessed from the perspectives mentioned above. Results will be generated during August 2014 and comprise both single-product LCA and region-wide impacts of the future scenarios.
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| 4. |
- Favereau, Ludovic, et al.
(författare)
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A Molecular Tetrad That Generates a High-Energy Charge-Separated State by Mimicking the Photosynthetic Z-Scheme
- 2016
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 138:11, s. 3752-3760
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Tidskriftsartikel (refereegranskat)abstract
- The oxygenic photosynthesis of green plants, green algae, and cyanobacteria is the major provider of energy rich compounds in the biosphere. The so-called "Z-scheme" is at the heart of this "engine of life". Two photosystems (photo system I and II) work in series to build up a higher redox ability than each photosystem alone can provide, which is necessary to drive water oxidation into oxygen and NADP(+) reduction into NADPH with visible light. Here we show a mimic of the Z-scheme with a molecular tetrad. The "tetrad Bodipy-NDI-TAPD-Ru is composed of two different dyes-4,4-difluoro-1,3,5,7-tetramethyl-2,6-diethy1-4-bora-3a,4a-diaza-s-indacene (Bodipy) and a Ru-II(bipyridine), (Ru) derivative-which are connected to a naphthalene diimide (NDI) electron acceptor and tetraalkylphenyldiamine (TAPD) playing the role of electron donor. A strong laser pulse excitation of visible light where the two dye molecules (Ru and Bodipy) absorb with equal probability leads to the cooperative formation of a highly energetic charge-separated state composed of an oxidized Bodipy and a reduced Ru. The latter state cannot be reached by one single photon absorption. The energy of the final charge-separated state (oxidized Bodipy/reduced Ru) in the tetrad lies higher than that in the reference dyads (Bodipy-NDI and TAPD-Ru), leading to the energy efficiency of the tetrad being 47% of the sum of the photon threshold energies. Its lifetime was increased by several orders of magnitude compared to that in the reference dyads Bodipy-NDI and TAPD-Ru, as it passes from about 3 ns in each dyad to 850 ns in the tetrad. The overall quantum yield formation of this extended charge-separated state is estimated to be 24%. Our proof-of-concept result demonstrates the capability to translate a crucial photosynthetic energy conversion principle into man-made molecular systems for solar fuel formation, to obtain products of higher energy content than those produced by a single photon absorption.
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| 5. |
- Favereau, Ludovic, et al.
(författare)
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Tris-bipyridine based dinuclear ruthenium(II)--osmium(III) complex dyads grafted onto TiO2 nanoparticles for mimicking the artificial photosynthetic Z-scheme
- 2017
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry. - 1463-9076 .- 1463-9084. ; 19:6, s. 4778-4786
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Tidskriftsartikel (refereegranskat)abstract
- The Z-Scheme function within molecular systems has been rarely reported for solar energy conversion although it offers the possibility to achieve higher efficiency than single photon absorber photosystems due to the use of a wider range of visible light. In this study, we synthesized and investigated the electrochemical and spectroscopic properties of two new dyads based on ruthenium and osmium tris-bipyridine complexes covalently linked via a butane bridge to explore their ability to realize the Z-scheme function once immobilized on TiO2. These dyads can be grafted onto a nanocrystalline TiO2 film via the osmium complex bearing two dicarboxylic acid bipyridine ligands, while the ruthenium complex contains either two unsubstituted bipyridine ancillary ligands (RuH-Os) or two (4,4'-bis-trifluoro-methyl-bipyridine) ancillary ligands (RuCF3-Os). Transient absorption spectroscopy studies of the Ru(II)-Os(III) dyads with femtosecond and nanosecond lasers were conducted both in solution and on TiO2. For both conditions, the photophysical studies revealed that the MLCT excited state of the ruthenium complex is strongly quenched and predominantly decays by energy transfer to the LMCT of the adjacent Os(III) complex, in spite of the high driving force for electron transfer. This unexpected result, which is in sharp contrast to previously reported Ru(II)-Os(III) dyads, precluded us to achieve the expected Z-scheme function. However, the above results may be a guide for designing new artificial molecular systems reproducing the complex function of a Z-scheme with molecular systems grafted onto a TiO2 mesoporous film.
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| 9. |
- Göransson, Anna-Lena, et al.
(författare)
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Dissecting the Aggregation Events of Alzheimer’s disease Associated Aβ peptide Variants by the Combined use of Different Fluorescent Probes
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The formation of soluble prefibrillar oligomeric species of the amyloid β peptide (Aβ) has been implicated as a causative agent in the development of Alzheimer’s disease (AD). It is therefore important to characterize the properties of these aggregates, which precede the formation of amyloid fibrils. We studied the in vitro aggregation process of two Aβ40 peptide variants through the combined use of four different fluorescent probes and transmission electron microscopy. Previous studies have shown that these two studied Aβ40 variants exhibit different levels of neurodegeneration when expressed in the central nervous system of Drosophila melanogaster. In the present study, we demonstrate distinct differences in aggregate morphology and their binding properties to different fluorescent probes during in vitro fibrillation of these Aβ peptides. Our results indicate a potential link between the observed neurodegenerative properties and the biophysical properties of distinct aggregated Aβ species.
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| 10. |
- Göransson, Erik
(författare)
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Bridge Mediated Electron Transfer in Conjugated and Cross-Conjugated Donor-Acceptor Compounds
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Detailed understanding of electron transfer reactions is important in many aspects of chemistry, biology and solar energy conversion.The main aim of this thesis is to provide further insight into electron transfer through highly conjugated bridge structures. Towards this end, three series of donor-acceptor dyads have been studied, all using an oligo(1,4-phenylene-ethynylene) moiety as the bridge. A common theme in these series is that they explore the effects of having either an ethynylene or phenylene as the attachment group between the bridge and the donor or acceptor. Photophysical characterization of these dyads was carried out by means of time resolved laser spectroscopy. The results show that having an ethynylene as attachment group results in higher rates for bridge mediated electron and energy transfer compared to similar systems, where a phenylene was used.It was also found that most of the investigated systems show a fast back electron transfer. A notable exception is a zinc(II) phthalocyanine- gold(III) porphyrin dyad, where very fast photoinduced electron transfer (kPET = 1.0×1012 s-1) was followed by relatively slow back electron transfer (kBET = 1.0×109 s-1). A complementary DFT investigation indicated that the charge shifted state involves a reduction of the gold ion, rather than the porphyrin ring. This results in lower electronic coupling between the reduced gold porphyrin and the bridge and thus slower back electron transfer.A series of zinc porphyrin platinum acetylide dyads was used to explore the effects on electronic coupling of different attachments points on the porphyrin ring. For the investigated system it was found that linking at the meso-position results in an eight-fold increase in electron transfer rate compared to the β-position.In addition, a series of mixed valence compounds was used to investigate electronic coupling mediated by cross-hyperconjugated or cross-π-conjugated bridges. The results indicate coupling elements of 100-400 cm-1, with the cross-π-conjugated bridge having the largest coupling. A complementary TD-DFT study indicates that both through bond and through space coupling can be active in these systems. The relative contribution of these two mechanisms to the electronic coupling is highly conformer dependent.
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