Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Entropy of aqueous surfaces. Application to polymeric Langmuir films
Deschênes, Louise ; Lyklema, Hans ; St-Germain, François - \ 2017
Advances in Colloid and Interface Science 247 (2017). - ISSN 0001-8686 - p. 149 - 162.
Jones-Ray effect - Langmuir monolayers - PEO - PPO - Surface entropy - Surface tension
Measuring surface (excess) entropies provides a bounty of valuable structural information that is hard to obtain otherwise. In the paper these quantities are defined and procedures of measurements discussed. Mostly they involve measurements at different temperatures. A review is given for interfaces with aqueous solutions in the absence of polymers. This review illustrates how, sometimes unanticipated, pieces of information are obtained, for example with cloud seeding and a possible explanation of the Jones-Ray effect. As a novel extension the procedure is applied to deposited, or Langmuir, monolayers of poly(ethylene oxide)-poly(propylene oxide) block copolymers. It will be shown how the various phase transitions and associated configurations of these polymers can be recognized and monitored.
Boosting LPMO-driven lignocellulose degradation by polyphenol oxidase-activated lignin building blocks
Frommhagen, Matthias ; Mutte, Sumanth Kumar ; Westphal, Adrie H. ; Koetsier, Martijn J. ; Hinz, Sandra W.A. ; Visser, Jaap ; Vincken, Jean Paul ; Weijers, Dolf ; Berkel, Willem J.H. Van; Gruppen, Harry ; Kabel, Mirjam A. - \ 2017
Biotechnology for Biofuels 10 (2017)1. - ISSN 1754-6834
Agaricus bisporus - Ascomycota - Basidiomycota - Catechol oxidase - Lignocellulose - LPMO - Myceliophthora thermophila C1 - Phenols - Polyphenol oxidase - PPO - Tyrosinase

Background: Many fungi boost the deconstruction of lignocellulosic plant biomass via oxidation using lytic polysaccharide monooxygenases (LPMOs). The application of LPMOs is expected to contribute to ecologically friendly conversion of biomass into fuels and chemicals. Moreover, applications of LPMO-modified cellulose-based products may be envisaged within the food or material industry. Results: Here, we show an up to 75-fold improvement in LPMO-driven cellulose degradation using polyphenol oxidase-activated lignin building blocks. This concerted enzymatic process involves the initial conversion of monophenols into diphenols by the polyphenol oxidase MtPPO7 from Myceliophthora thermophila C1 and the subsequent oxidation of cellulose by MtLPMO9B. Interestingly, MtPPO7 shows preference towards lignin-derived methoxylated monophenols. Sequence analysis of genomes of 336 Ascomycota and 208 Basidiomycota reveals a high correlation between MtPPO7 and AA9 LPMO genes. Conclusions: The activity towards methoxylated phenolic compounds distinguishes MtPPO7 from well-known PPOs, such as tyrosinases, and ensures that MtPPO7 is an excellent redox partner of LPMOs. The correlation between MtPPO7 and AA9 LPMO genes is indicative for the importance of the coupled action of different monooxygenases in the concerted degradation of lignocellulosic biomass. These results will contribute to a better understanding in both lignin deconstruction and enzymatic lignocellulose oxidation and potentially improve the exploration of eco-friendly routes for biomass utilization in a circular economy.

Phase transitions in polymer monolayers : Application of the Clapeyron equation to PEO in PPO-PEO Langmuir films
Deschênes, Louise ; Lyklema, J. ; Danis, Claude ; Saint-Germain, François - \ 2015
Advances in Colloid and Interface Science 222 (2015). - ISSN 0001-8686 - p. 199 - 214.
Clapeyron - Monolayers - PEO - Phase transition - PPO

In this paper we investigate the application of the two-dimensional Clapeyron law to polymer monolayers. This is a largely unexplored area of research. The main problems are (1) establishing if equilibrium is reached and (2) if so, identifying and defining phases as functions of the temperature. Once this is validated, the Clapeyron law allows us to obtain the entropy and enthalpy differences between two coexisting phases. In turn, this information can be used to obtain insight into the conformational properties of the films and changes therein. This approach has a wide potential for obtaining additional information on polymer adsorption at interfaces and the structure of their monolayer films. The 2D Clapeyron law was applied emphasizing polyethylene oxide (PEO) in polypropylene oxide (PPO)-PEO block copolymers, based on new well-defined data for their Langmuir films. Values for enthalpy per monomer of 0.12 and 0.23 kT were obtained for the phase transition of two different PEO chains (Neo of 2295 and 409, respectively). This enthalpy was estimated to correspond to 1.2 ± 0.4 kT per EO monomer present in train conformation at the air/water interface.

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