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.

    We have a manual that explains all the features 

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    Coupling between electrokinetics and electrode kinetics by bipolar faradaic depolarisation processes in microfluidic channels
    Duval, Jérôme F.L. ; Leeuwen, Herman P. van - \ 2020
    Advances in Colloid and Interface Science 275 (2020). - ISSN 0001-8686
    Bipolar electrochemistry - Electrode kinetics - Electrokinetics - Microfluidics - Streaming potential

    This article is concerned with the nature and impact of bipolar faradaic electron transfer processes in the context of measuring electrokinetic parameters at the interface between an electronically conductive substrate such as a solid metal layer, and a liquid medium. More specifically, it analyses the steady state electric current through the electrodic substrate layer in terms of its short-circuiting effect on the system's electrokinetic quantities, such as the streaming potential. Ample attention is paid to the electrodic behaviour of the chosen metal and its electron transfer characteristics with respect to redox functions in the medium. The electrochemical reversibility of redox couple species is expressed in terms of their oxidation and reduction rate constants as compared to their diffusive transport rates under lateral flow conditions. High values for rate constants lead to high reversibilities and large bipolar leaking currents through the metal substrate. In turn, high electron transfer rate constants generate large reductions in measured values for electrokinetic quantities such as streaming potentials that further become a non-linear function of the pressure gradient applied through the fluidic chamber. The present article presents an overview of theoretical and experimental approaches of this intricate coupling between bipolar electrode kinetics and electrokinetics and the impact from Hans Lyklema's contributions. It highlights not only the implications of bipolar faradaic depolarisation processes in electrokinetics but also the importance of bipolar electrochemistry principles in various electroanalytical applications reported for e.g. the control of microfluidic flows, for surfaces functionalisation, particles manipulation or for the wireless detection of electroactive analytes.

    Persistency of the 3-nitrooxypropanol effect on methane and hydrogen emissions in postpartum Holstein-Friesian dairy cows
    Gastelen, S. van; Dijkstra, J. ; Binnendijk, G.P. ; Duval, Stéphane M. ; Heck, Jeroen M.L. ; Kindermann, Maik ; Zandstra, T. ; Bannink, A. - \ 2019
    In: Proceedings of the 7th GGAA - Greenhouse Gas and Animal Agriculture Conference. - Iguassu Falls/Brazil : Embrapa (Proceedings 135) - p. 109 - 109.
    Identification of Climate and Genetic Factors That Control Fat Content and Fatty Acid Composition of Theobroma cacao L. Beans
    Mustiga, Guiliana M. ; Morrissey, Joe ; Stack, Joseph Conrad ; DuVal, Ashley ; Royaert, Stefan ; Jansen, Johannes ; Bizzotto, Carolina ; Villela-Dias, Cristiano ; Mei, Linkai ; Cahoon, Edgar B. ; Seguine, Ed ; Marelli, Jean Philippe ; Motamayor, Juan Carlos - \ 2019
    Frontiers in Plant Science 10 (2019). - ISSN 1664-462X
    cacao - fat content - fatty acid composition - heritability - linkage mapping - QTL - SNP - weather

    The main ingredients of chocolate are usually cocoa powder, cocoa butter, and sugar. Both the powder and the butter are extracted from the beans of the cacao tree (Theobroma cacao L.). The cocoa butter represents the fat in the beans and possesses a unique fatty acid profile that results in chocolate’s characteristic texture and mouthfeel. Here, we used a linkage mapping population and phenotypic data of 3,292 samples from 420 progeny which led to the identification of 27 quantitative trait loci (QTLs) for fatty acid composition and six QTLs for fat content. Progeny showed extensive variation in fat levels and composition, with the level of palmitic acid negatively correlated to the sum of stearic acid, oleic acid, and linoleic acid. A major QTL explaining 24% of the relative level of palmitic acid was mapped to the distal end of chromosome 4, and those higher levels of palmitic acid were associated with the presence of a haplotype from the “TSH 1188” parent in the progeny. Within this region of chromosome 4 is the Thecc1EG017405 gene, an orthologue and isoform of the stearoyl-acyl carrier protein (ACP) desaturase (SAD) gene in plants, which is involved in fatty acid biosynthesis. Besides allelic differences, we also show that climate factors can change the fatty acid composition in the beans, including a significant positive correlation between higher temperatures and the higher level of palmitic acid. Moreover, we found a significant pollen donor effect from the variety “SIAL 70” which was associated with decreased palmitic acid levels.

    Rigorous Physicochemical Framework for Metal Ion Binding by Aqueous Nanoparticulate Humic Substances: Implications for Speciation Modeling by the NICA-Donnan and WHAM Codes
    Town, Raewyn M. ; Leeuwen, Herman P. Van; Duval, Jérôme F.L. - \ 2019
    Environmental Science and Technology 53 (2019)15. - ISSN 0013-936X - p. 8516 - 8532.

    Latest knowledge on the reactivity of charged nanoparticulate complexants toward aqueous metal ions is discussed in mechanistic detail. We present a rigorous generic description of electrostatic and chemical contributions to metal ion binding by nanoparticulate complexants, and their dependence on particle size, particle type (i.e., reactive sites distributed within the particle body or confined to the surface), ionic strength of the aqueous medium, and the nature of the metal ion. For the example case of soft environmental particles such as fulvic and humic acids, practical strategies are delineated for determining intraparticulate metal ion speciation, and for evaluating intrinsic chemical binding affinities and heterogeneity. The results are compared with those obtained by popular codes for equilibrium speciation modeling (namely NICA-Donnan and WHAM). Physicochemical analysis of the discrepancies generated by these codes reveals the a priori hypotheses adopted therein and the inappropriateness of some of their key parameters. The significance of the characteristic time scales governing the formation and dissociation rates of metal-nanoparticle complexes in defining the relaxation properties and the complete equilibration of the metal-nanoparticulate complex dispersion is described. The dynamic features of nanoparticulate complexes are also discussed in the context of predictions of the labilities and bioavailabilities of the metal species.

    Farm-specific failure costs of production disorders in European organic dairy herds
    Soest, F.J.S. van; Mourits, M.C.M. ; Blanco-Penedo, I. ; Duval, J. ; Fall, N. ; Krieger, M. ; Sjöstrom, K. ; Hogeveen, H. - \ 2019
    Preventive Veterinary Medicine 168 (2019). - ISSN 0167-5877 - p. 19 - 29.
    Animal health economics - Ketosis - Lameness - Mastitis - Metritis

    On-farm decision support in animal health management requires a tailor-made failure costs (FCs) assessment of production disorders for the individual farm. In our study we defined a generic framework to estimate the FC of production disorders in dairy cows. We converted the framework to a practical tool in which the farm-specific FC of mastitis, ketosis, lameness and metritis were estimated for 162 organic dairy farms in four European countries. Along with the structure of the framework, the FC estimation required three distinct types of model input: performance input (related to herd performance parameters), consequential input (related to the consequences of the disorders) and economic input (related to price levels). Input was derived from official herd recordings (e.g. test-day records and animal health recordings) and farmers’ responses (e.g. questionnaire replies). The average FC of mastitis, ketosis, lameness and metritis amounted to € 96, € 21, € 43 and € 10 per cow per year, respectively. The variation in FC outcomes was high among farmers and countries. Overall ranking of the disorders based on absolute values was the same for all countries, with mastitis being the costliest disorder followed in order by lameness, ketosis, and metritis. Farm specific estimates can be used to rank production related disorders in terms of their associated failure costs and thus provide valuable insights for herd health management. The practical calculation tool developed in this study should be considered by farmers or herd health advisors to support their animal health practices or advice.

    Structural characteristics of organic dairy farms in four European countries and their association with the implementation of animal health plans
    Blanco-Penedo, Isabel ; Sjöström, Karin ; Jones, Philip ; Krieger, Margret ; Duval, Julie ; Soest, Felix van; Sundrum, Albert ; Emanuelson, Ulf - \ 2019
    Agricultural Systems 173 (2019). - ISSN 0308-521X - p. 244 - 253.
    Animal health, farm typologies - Cluster analysis - Multiple correspondence analysis - Organic dairy system - Tailored advisory services

    The aim of the present study was to classify the diversity of organic dairy farms in four European countries according to their structural characteristics and investigate the association of these farm types with implementation of herd health plans. A Multiple Correspondence Analysis (MCA), followed by Agglomerative Hierarchical Clustering (AHC), was used to classify the farms. Data for the analysis came from a survey of 192 organic farms from France, Germany, Spain and Sweden and contained farm and farmer descriptions from which the typologies were derived. Herd health plans was agreed for each farm, via a participatory approach involving the farmers, their veterinarians and other advisors (e.g. dairy advisors) by the use of an impact matrix. The MCA yielded two principal component axes explaining 51.3% of variance. Three farm groups were identified by AHC using the factor scores derived from the MCA. Cluster 1, the most numerous group (56.7% of the sample), had medium herd sizes with moderate use of pasture and moderate intensity of input use. Cluster 2, representing 17.7% of the sample, were the most extensive system and mainly of very small farm size. Cluster 3 (25.5% of the sample and only found in Sweden), had an intensive management approach, but relatively low stocking rate. The analysis also showed that organic dairy farms adopted differentiated strategies towards economic assets and animal health status, according to group membership. The typology therefore provides insights into the potential for advisory strategies relating to husbandry practices, different housing, pasture management and intensity, etc. adapted to different groups of farms. Regarding herd health plan implementation, Cluster 1 was the group with most implemented actions and Cluster 2 with lowest rate of implemented actions. These results may be used as background for directing (tailored) advice strategies, i.e. different types of organic dairy farms (clusters) may require different types of advisory services and recommendations adapted to the specific farm situation in order to deliver future improvements in animal health.

    The Intrinsic Stability of Metal Ion Complexes with Nanoparticulate Fulvic Acids
    Town, Raewyn M. ; Duval, Jérôme F.L. ; Leeuwen, Herman P. van - \ 2018
    Environmental Science and Technology 52 (2018)20. - ISSN 0013-936X - p. 11682 - 11690.

    The electrostatic contributions to metal ion binding by fulvic acids (FAs) are characterized in light of recent theoretical developments on description of the net charge density of soft nanoparticles. Under practical electrolyte concentrations, the radius of the small, highly charged soft nanoparticulate FAs is comparable to the electrostatic screening length and their electric potential profile has a bell shape that extends into the surrounding aqueous medium. Consequently, accumulation of counterions in the extraparticulate zone can be significant. By comparison of experimentally derived Boltzmann partitioning coefficients with those computed on the basis of (i) the structural FA particle charge and (ii) the potential profile for a nanoparticulate FA entity equilibrated with indifferent electrolyte, we identify the thickness of the extraparticulate counter charge accumulation shell in 1-1 and 2-1 electrolytes. The results point to the involvement of counterion condensation phenomena and call into question the approaches for modeling electrostatic contributions to ion binding that are invoked by popular equilibrium speciation codes. Overall, the electrostatic contributions to Cdaq2+ and Cuaq2+ association with FA are weaker than those previously found for much larger humic acids (HA). The intrinsic chemical binding strength of CdFA is comparable to that of CdHA, whereas CuFA complexes are weaker than CuHA ones.

    Poisson-Boltzmann Electrostatics and Ionic Partition Equilibration of Charged Nanoparticles in Aqueous Media
    Duval, Jérôme F.L. ; Town, Raewyn M. ; Leeuwen, Herman P. van - \ 2018
    The Journal of Physical Chemistry Part C: Nanomaterials and Interfaces 122 (2018)30. - ISSN 1932-7447 - p. 17328 - 17337.

    Most nanoparticles (NPs) dispersed in aqueous media carry a net charge. The ensuing electric field plays a fundamental role in determining the thermodynamic and chemodynamic features of the interactions between NPs and dissolved metal species and their lability and bioavailability in environmental and biological matrices. Although increasing attention is being paid to the analysis of metal ion speciation in dispersions of charged complexing NPs, so far the electrostatic features of NPs have only been described on the sole basis of their structural charge properties, that is, the number of (potentially) charged groups they carry. This approach intrinsically ignores the impact of counterion accumulation at/within the particle body/surface during equilibration of the system, which effectively lowers the magnitude of the net NP charge density. Herein, we present the first analysis of the potential profile of NPs after their physicochemical equilibration with the aqueous medium, and we discuss the implications thereof in terms of counterion accumulation within and/or in the vicinity of hard, soft, and core-shell NPs. The focus is on soft or core-soft shell NPs in the thick double layer limit for which bulky Donnan features are not applicable. The new conceptual framework identifies the spatial zone over which divalent counterion accumulation is significant as a function of size, charge density, and type of NP, as well as the ionic strength and electrolyte composition (1-1 and 2-1) of the aqueous medium for the most common case of negatively charged NPs.

    Lability of Nanoparticulate Metal Complexes at a Macroscopic Metal Responsive (Bio)interface : Expression and Asymptotic Scaling Laws
    Duval, Jérôme F.L. ; Town, Raewyn M. ; Leeuwen, Herman P. Van - \ 2018
    The Journal of Physical Chemistry Part C: Nanomaterials and Interfaces 122 (2018)11. - ISSN 1932-7447 - p. 6052 - 6065.
    The lability of metal complexes expresses the extent of the dissociative contribution of the complex species to the flux of metal ions toward a macroscopic metal-responsive (bio)interface, for example, an electrodic sensor or an organism. While the case of molecular ligands is well-established, it is only recently that a definition was elaborated for the lability of metal complexes with nanoparticles (NPs) in aqueous dispersions. The definition includes the thickness of the nonequilibrium reaction layer operational at the (bio)interface and the extent of geometrical exclusion of NPs therefrom. In this work, an explicit expression is derived for the lability of nanoparticulate metal complexes (M-NP) toward a macroscopic reactive (bio)interface. Interpretation accounts for the M-NP chemodynamic properties that depend on the NP size, electrostatics, metal diffusion and dehydration rates, and density of metal binding sites for various NP types, for example, soft/core-shell and hard NPs having volume and surface site distribution, respectively. Computational examples under practical conditions illustrate how these factors jointly determine the remarkable nonmonotonous dependence of the M-NP lability parameter on the NP size. The analysis is supported by the formulation of asymptotic scaling laws clarifying how local M-NP dissociation dynamics affect the lability parameter for M-NP complexes at the scale of the macroscopic (bio)interface.
    Chemodynamics and bioavailability of metal ion complexes with nanoparticles in aqueous media
    Leeuwen, Herman P. Van; Duval, Jérôme F.L. ; Pinheiro, José Paulo ; Blust, Ronny ; Town, Raewyn M. - \ 2017
    Environmental Science: Nano covers the benefits... 4 (2017)11. - ISSN 2051-8153 - p. 2108 - 2133.
    Nanoparticles (NPs) exhibit unique reactivity features that stem from the spatial confinement of their reactive sites to the particle body, which typically carries electric charges. Accordingly, association of ions and molecules with NPs takes place in a local environment that may be very different from that prevailing in the bulk aqueous medium. We present a critical overview of a conceptual framework that describes the dynamic features of metal ion, M, association with different types of NPs, i.e. impermeable (hard, 2D), core-shell, and permeable (soft, 3D). The interpretation identifies the crucial role played by the particulate electric field, and elucidates the factors that determine which step in the overall association/dissociation process is the rate-limiting one. The scope encompasses delineation of the distribution of NP-associated metals, M-NP, over various intraparticulate forms, as well as description of the influence of the intraparticulate spatial distribution of reactants on the complex formation/dissociation kinetics. The connection between the chemodynamic features of M-NP entities at the intraparticulate level and their reactivity at the macroscopic scale is elaborated. These relationships are used to derive analytical expressions for the lability of M-NP entities at reactive interfaces, such as sensors and organisms. Such knowledge is required to make mechanistic links with bioavailability and ensuing toxicity. The interpretation includes formulation of the operational reaction layer at the macroscopic interface and the significance of partial size exclusion of the NP body therefrom. The concepts are illustrated by confrontation with sets of experimental data for different types of natural and engineered NPs.
    Applicability of the Reaction Layer Principle to Nanoparticulate Metal Complexes at a Macroscopic Reactive (Bio)Interface : A Theoretical Study
    Duval, Jérôme F.L. ; Town, Raewyn M. ; Leeuwen, Herman P. Van - \ 2017
    The Journal of Physical Chemistry Part C: Nanomaterials and Interfaces 121 (2017)35. - ISSN 1932-7447 - p. 19147 - 19161.
    The reaction layer concept is commonly adopted to estimate the contribution of metal complexes to the flux of free metal ions (M) toward a macroscopic M-accumulating (bio)interface, e.g., a biosurface (microorganism) or a sensor (electrode). This concept is well-established for molecular ligands homogeneously distributed in solution. However, the case of (nano)particulate complexants carrying metal binding sites within their body or at their surface has so far received scant attention. In this study, a formalism is elaborated to evaluate the thickness λ of the reaction layer that is operational for (nano)particulate metal complexes at a macroscopic metal-sensing (bio)interface. The theory integrates the relevant chemodynamic properties of nanoparticulate metal complexes as governed by the interplay between M conductive diffusion to/from the nanoparticulate complexants and the dissociation kinetics of inner-sphere complexes between M and particle-supported binding sites. The intricate dependence of λ on particle size, particle type, particle charge, the density/number of metal binding sites, and the nature of the metal ion is physically interpreted with the aid of computational illustrations. Analytical formulations are further derived in the extremes where reaction layer properties are dominated by either diffusion-controlled or kinetically controlled dissociation of nanoparticulate metal complexes. The results constitute a solid physicochemical basis for elaboration to lability of nanoparticulate complexes at macroscopic reactive (bio)interfaces, a central theme in biouptake and toxicity of metals. In particular, the here-reported formalism is shown to successfully predict the lability of metal-polymer nanoparticle complexes as determined from voltammetric measurements. It is further evidenced that conventional approaches ignoring particle body exclusion from the reaction layer may dramatically overestimate, by several orders of magnitude, the true kinetic flux arising from the rate of dissociation of nanoparticulate metal species at a macroscopic reactive interface.
    Selective on-line detection of boronic acids and derivatives in high-performance liquid chromatography eluates by post-column reaction with alizarin
    Duval, F.L. ; Wardani, P.A. ; Zuilhof, H. ; Beek, T.A. van - \ 2015
    Journal of Chromatography. A, Including electrophoresis and other separation methods 1417 (2015). - ISSN 0021-9673 - p. 57 - 63.
    An on-line high-performance liquid chromatography (HPLC) method for the rapid and selective detection of boronic acids in complex mixtures was developed. After optimization experiments at an HPLC flow rate of 0.40 mL/min, the HPLC-separated analytes were mixed post-column with a solution of 75 µM alizarin and 0.1% triethylamine in acetonitrile, which was delivered at a flow rate of 0.60 mL/min. The reaction between alizarin and boronic acids occurred in a reaction coil of dimensions of 3.5 m × 0.25 mm at a temperature of 50 °C, resulting in fluorescent complexes that were detected as positive peaks by a fluorescence detector (¿exc 469 nm and ¿em 610 nm). The method enabled the selective detection of various boronic acids and derivatives, with a limit of detection of phenylboronic acid of 1.2 ng or 1 µM. It could successfully monitor the progress of two organic reactions involving boronic acid-containing compounds, and provided useful insights into the course of the reactions.
    New applications of the interaction between diols and boronic acids
    Duval, F.L. - \ 2015
    Wageningen University. Promotor(en): Han Zuilhof, co-promotor(en): Teris van Beek. - Wageningen : Wageningen University - ISBN 9789462574717 - 131
    antilichamen - immobilisatie - boorzuur - biomarkers - vloeistofchromatografie - antibodies - immobilization - boric acid - biomarkers - liquid chromatography

    Florine Duval - New applications of the interaction between diols and boronic acids – Summary

    Chapter 1 introduces the theory and known applications of the interaction between boronic acids and diols, and explains the context of this thesis. Diagnosis of depression was the initial goal of this multidisciplinary project. The focus of the PhD project was the development of a strategy to immobilize antibodies on the surface of a chip in such a way that very low concentrations (~ 1 pM) of biomarkers for depression could be detected in urine. To achieve this, the immobilization of antibodies using boronic acids seemed promising.

    However, preliminary experiments and further insights revealed the many challenges that this immobilization strategy faces, giving rise to Chapter 2. This chapter discusses several important points that need to be taken into account when one plans to immobilize antibodies via boronic acids: choice of the boronic acid structure and spacer to attach it to the surface, use of an antifouling polymer, choice of an antibody with suitable glycosylation, optimization of the conditions for antibody immobilization...

    One big issue for antibody immobilization using boronic acids is the reversibility of the reaction between boronic acids and diols, hence the possible release of the antibody from the surface.

    Chapter 3 describes the design and synthesis of boronic acid-containing linkers that would enable the oriented and irreversible immobilization of antibodies. Two linkers were designed with an amine for surface attachment, a boronic acid for capturing antibodies via the N-glycans in their Fc chain, and a diazirine for irreversible immobilization upon UV irradiation while maintaining antibody orientation. From a diazirine building-block that was obtained in three steps, the first linker was synthesized in four steps and the second linker was synthesized in three steps. Diol-functionalized silica was used for the chromatography of two boronic acid-containing intermediates, this method being novel (to the best of our knowledge) and likely based on boronic acid-diol interactions. High-resolution mass spectrometry, through matching exact masses, matching isotope patterns and observation of species corresponding to the esterification of boronic acids with MeOH, confirmed that both linkers were synthesized successfully.

    During the synthesis of boronic acid-containing linkers, it was difficult to see which spots on TLC plates corresponded to boronic acids. To solve this problem, a new TLC staining method based on the reaction between boronic acids and alizarin was developed.

    Chapter 4 presents this work in detail. After optimization experiments, 1 mM alizarin in acetone was shown to be the preferred staining solution. When the TLC plate was briefly dipped in this solution, allowed to dry in ambient air and observed under 365 nm light, bright yellow fluorescent spots were observed where boronic acids were present. Phenylboronic acid was detected at a concentration as low as 0.1 mM. A range of boronic acids and derivatives was successfully detected, and boron-free compounds resulted in no or very weak fluorescence. The staining method was further tested in the monitoring of three reactions involving boronic acids, and provided clear information about the consumption or formation of boronic acid-containing compounds.

    Although TLC is useful to synthetic chemists, analysis of reaction mixtures by HPLC is sometimes necessary for obtaining more accurate information or for optimization of preparative HPLC conditions.

    Chapter 5 presents the development and applicability of a method for the on-line HPLC detection of boronic acids using alizarin. After optimization experiments at an HPLC flow rate of 0.40 mL/min, the HPLC-separated analytes were mixed post-column with a solution of 75 μM alizarin and 0.1% triethylamine in ACN, which was delivered at a flow rate of 0.60 mL/min. The reaction between alizarin and boronic acids occurred in a reaction coil of dimensions of 3.5 m × 0.25 mm at a temperature of 50 °C, resulting in fluorescent complexes that were detected as positive peaks by a fluorescence detector (lexc 469 nm and lem 610 nm). The method enabled the selective detection of various boronic acids and derivatives, with a limit of detection of phenylboronic acid of 1.2 ng or 1 μM. It could successfully monitor the progress of two organic reactions involving boronic acid-containing compounds, and provided useful insights into the course of the reactions.

    Chapter 6 provides a reflexion about the work presented in this thesis, suggestions for future research, and a general conclusion.

    Key steps towards the oriented immobilization of antibodies using boronic acids
    Duval, F.L. ; Beek, T.A. van; Zuilhof, H. - \ 2015
    The Analyst 140 (2015)19. - ISSN 0003-2654 - p. 6467 - 6472.
    Oriented immobilization of antibodies using boronic acids shows a strong potential for improving immunoassay performance but is not yet widely used, possibly because of the difficulties encountered in its implementation. How to choose the boronic acid structure and how should it be attached to the surface? How to choose an antibody that will bind to the boronic acid? Under which conditions should the binding take place for an effective oriented antibody immobilization? How to make sure that the antibody stays on the surface? This tutorial review provides answers to these questions through analysis of the literature and personal suggestions, and thereby intends to facilitate the development of this promising antibody immobilization strategy.
    Electrokinetics as an alternative to neutron reflectivity for evaluation of segment density distribution in PEO brushes
    Zimmermann, R. ; Romeis, D. ; Bihannic, I. ; Cohen Stuart, M.A. ; Sommer, J.U. ; Werner, C. ; Duval, J.F.L. - \ 2014
    Soft Matter 10 (2014)39. - ISSN 1744-683X - p. 7804 - 7809.
    poly(ethylene oxide) brushes - diffuse soft interfaces - grafted polymer brush - streaming current - aqueous-solution - behavior - films - water - thin - surfaces
    Unravelling details of charge, structure and molecular interactions of functional polymer coatings defines an important analytical challenge that requires the extension of current methodologies. In this article we demonstrate how streaming current measurements interpreted with combined self consistent field (SCF) and soft surface electrokinetic theories allow the evaluation of the segment distribution within poly(ethylene oxide) (PEO) brushes beyond the resolution limits of neutron reflectivity technique.
    Chemodynamics of soft Charged nanoparticles in aquatic media: Fundamental concepts
    Town, R.M. ; Buffle, J. ; Duval, J.F.L. ; Leeuwen, H.P. van - \ 2013
    The Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment, & General Theory 117 (2013)33. - ISSN 1089-5639 - p. 7643 - 7654.
    metal speciation dynamics - aqueous-solutions - solvent exchange - complexes - relaxation - nmr - ion - approximation - temperature - membranes
    Understanding the extraordinary ionic reactivity of aqueous nanoparticles
    Leeuwen, H.P. van; Buffle, J. ; Duval, J.F.L. ; Town, R.M. - \ 2013
    Langmuir 29 (2013)33. - ISSN 0743-7463 - p. 10297 - 10302.
    soft - chemodynamics - size - coagulation - relaxation - complexes - ligands - binding - cu(ii)
    Nanoparticles (NPs) are generally believed to derive their high reactivity from the inherently large specific surface area. Here we show that this is just the trivial part of a more involved picture. Nanoparticles that carry electric charge are able to generate chemical reaction rates that are even substantially larger than those for similar molecular reactants. This is achieved by Boltzmann accumulation of ionic reactants and the Debye acceleration of their transport. The ensuing unique reactivity features are general for all types of nanoparticles but most prominent for soft ones that exploit the accelerating mechanisms on a 3D level. These features have great potential for exploitation in the catalysis of ionic reactions: the reactivity of sites can be enhanced by increasing the indifferent charge density in the NP body
    Saturated fat stimulates obesity and hepatic steatosis and affects gut microbiota composition by an enhanced overflow of dietary fat to the distal intestine
    Wit, Nicole de; Oosterink, Els ; Bosch-Vermeulen, Hanneke ; Keshtkar, Shohreh ; Duval, C.N.C. ; Vogel-van den Bosch, Johan de; Muller, Michael ; Meer, Roelof van der - \ 2012
    Mus musculus - GSE18586 - PRJNA120299
    We studied the effect of dietary fat type, varying in polyunsaturated/saturated fatty acid ratio's (P/S) on development of metabolic syndrome. C57Bl/6J mice were fed purified high-fat diets (45E% fat) containing palm oil (HF-PO; P/S 0.4), olive oil (HF-OO; P/S 1.1) or safflower oil (HF-SO; P/S 7.8) for 8 weeks. A low-fat palm oil diet (LF-PO; 10E% fat) was used as a reference. Additionally, we analyzed diet-induced changes in gut microbiota composition and mucosal gene expression. The HF-PO diet induced a higher body weight gain and liver triglyceride content compared to the HF-OO, HF-SO or LF-PO diet. In the intestine, the HF-PO diet reduced microbial diversity and increased the Firmicutes/Bacteroidetes ratio. Although this fits a typical obesity profile, our data clearly indicate that an overflow of the HF-PO diet to the distal intestine, rather than obesity itself, is the main trigger for these gut microbiota changes. A HF-PO diet-induced elevation of lipid metabolism-related genes in the distal small intestine confirmed the overflow of palm oil to the distal intestine. Some of these lipid metabolism-related genes were previously already associated with the metabolic syndrome. In conclusion, our data indicate that saturated fat (HF-PO) has a more stimulatory effect on weight gain and hepatic lipid accumulation than unsaturated fat (HF-OO and HF-SO). The overflow of fat to the distal intestine on the HF-PO diet induced changes in gut microbiota composition and mucosal gene expression. We speculate that both are directly or indirectly contributive to the saturated fat-induced development of obesity and hepatic steatosis.
    Sensitive Thin-Layer Chromatography Detection of Boronic Acids Using Alizarin
    Duval, F.L. ; Beek, T.A. van; Zuilhof, H. - \ 2012
    Synlett: accounts and rapid communications in synthetic organic chemistry 23 (2012)12. - ISSN 0936-5214 - p. 1751 - 1754.
    phenylboronic acid - suzuki reaction - part 2 - diol
    A new method for the selective and sensitive detection of boronic acids on thin-layer chromatography plates is described. The plate is briefly dipped in an alizarin solution, allowed to dry in ambient air, and observed under 366 nm light. Alizarin emits a bright yellow fluorescence only in the presence of a boronic acid.
    Sub-report-B - Update of influence of genetic parameters on the welfare and the resistance to stress of commercial broilers in De Jong, I., Berg, C., Butterworth, A. Estevéz, I. (Eds.) Scientific report updating the EFSA opinions on the welfare of broilers and broiler breeders
    Berg, C. ; Butterworth, A. ; Bihan-Duval, E. Le; Caplen, G. ; Ferrari, P. ; Jong, I.C. de; Rodenburg, T.B. ; Sorensen, P. ; Steenfeldt, S. ; Veldkamp, T. - \ 2012
    European Food Safety Authority - 116 p.
    broilers - broiler breeders - animal housing - animal welfare - animal genetics - poultry housing - animal health - animal production - poultry - animal behaviour - animal nutrition
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