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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    Evaluation of the impact of extrinsic rewards on user engagement in a health promotion context
    Nuijten, Raoul C.Y. ; Gorp, Pieter M.E. Van; Kaymak, Uzay ; Simons, Monique ; Kemperman, Astrid D.A.M. ; Berg, Pauline E.W. Van Den - \ 2019
    In: 41st Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBC 2019. - Berlin, Germany : Institute of Electrical and Electronics Engineers Inc. (Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS ) - ISBN 9781538613115 - p. 3600 - 3604.
    extrinsic rewards - health promotion - mHealth - social proof principle

    Despite the many mHealth solutions available, it remains unclear what their success factors are. Specifically, there has been controversy on the effectiveness of extrinsic rewards. This study evaluates two design elements of an mHealth solution -i.e., social proof and tangible rewards -and their impact on user engagement. During a four-week campaign, a sample of 143 university staff members engaged in a health promotion campaign. Participants were randomly distributed over one of three treatment groups. It was found that the introduction of a sufficiently meaningful, unexpected, and customized extrinsic reward can engage participants significantly more in a health promotion context.

    Assessment of heterosis in two arabidopsis thaliana common-reference mapping populations
    Hulten, Marieke H.A. van; Paulo, Maria Joāo ; Kruijer, Willem ; Blankestijn-de Vries, Hetty ; Kemperman, Brend ; Becker, Frank F.M. ; Yang, Jiaming ; Lauss, Kathrin ; Stam, Maike E. ; Eeuwijk, Fred A. van; Keurentjes, Joost J.B. - \ 2018
    PLoS ONE 13 (2018)10. - ISSN 1932-6203

    Hybrid vigour, or heterosis, has been of tremendous importance in agriculture for the improvement of both crops and livestock. Notwithstanding large efforts to study the phenomenon of heterosis in the last decades, the identification of common molecular mechanisms underlying hybrid vigour remain rare. Here, we conducted a systematic survey of the degree of heterosis in Arabidopsis thaliana hybrids. For this purpose, two overlapping Arabidopsis hybrid populations were generated by crossing a large collection of naturally occurring accessions to two common reference lines. In these Arabidopsis hybrid populations the range of heterosis for several developmental and yield related traits was examined, and the relationship between them was studied. The traits under study were projected leaf area at 17 days after sowing, flowering time, height of the main inflorescence, number of side branches from the main stem or from the rosette base, total seed yield, seed weight, seed size and the estimated number of seeds per plant. Predominantly positive heterosis was observed for leaf area and height of the main inflorescence, whereas mainly negative heterosis was observed for rosette branching. For the other traits both positive and negative heterosis was observed in roughly equal amounts. For flowering time and seed size only low levels of heterosis were detected. In general the observed heterosis levels were highly trait specific. Furthermore, no correlation was observed between heterosis levels and the genetic distance between the parental lines. Since all selected lines were a part of the Arabidopsis genome wide association (GWA) mapping panel, a genetic mapping approach was applied to identify possible regions harbouring genetic factors causal for heterosis, with separate calculations for additive and dominance effects. Our study showed that the genetic mechanisms underlying heterosis were highly trait specific in our hybrid populations and greatly depended on the genetic background, confirming the elusive character of heterosis.

    Amplicon sequencing for the quantification of spoilage microbiota in complex foods including bacterial spores
    Boer, P. de; Caspers, M. ; Sanders, J.W. ; Kemperman, R. ; Wijman, J. ; Lommerse, G. ; Roeselers, G. ; Montijn, R. ; Abee, T. ; Kort, R. - \ 2015
    Microbiome 3 (2015)30. - ISSN 2049-2618 - 13 p.
    Background
    Spoilage of food products is frequently caused by bacterial spores and lactic acid bacteria. Identification of these organisms by classic cultivation methods is limited by their ability to form colonies on nutrient agar plates. In this study, we adapted and optimized 16S rRNA amplicon sequencing for quantification of bacterial spores in a canned food matrix and for monitoring the outgrowth of spoilage microbiota in a ready-to-eat food matrix.

    Results
    The detection limit of bar-coded 16S rRNA amplicon sequencing was determined for the number of bacterial spores in a canned food matrix. Analysis of samples from a canned food matrix spiked with a mixture of equinumerous spores from the thermophiles, Geobacillus stearothermophilus and Geobacillus thermoglucosidans, and the mesophiles, Bacillus sporothermodurans, Bacillus cereus, and Bacillus subtilis, led to the detection of these spores with an average limit of 2 × 102 spores ml−1. The data were normalized by setting the number of sequences resulting from DNA of an inactivated bacterial species, present in the matrix at the same concentration in all samples, to a fixed value for quantitative sample-to-sample comparisons. The 16S rRNA amplicon sequencing method was also employed to monitor population dynamics in a ready-to-eat rice meal, incubated over a period of 12 days at 7 °C. The most predominant outgrowth was observed by the genera Leuconostoc, Bacillus, and Paenibacillus. Analysis of meals pre-treated with weak acids showed inhibition of outgrowth of these three genera. The specificity of the amplicon synthesis was improved by the design of oligonucleotides that minimize the amplification of 16S rRNA genes from chloroplasts originating from plant-based material present in the food.

    Conclusion
    This study shows that the composition of complex spoilage populations, including bacterial spores, can be monitored in complex food matrices by bar-coded amplicon sequencing in a quantitative manner. In order to allow sample-to-sample comparisons, normalizations based on background DNA are described. This method offers a solution for the identification and quantification of spoilage microbiota, which cannot be cultivated under standard laboratory conditions. The study indicates variable detection limits among species of bacterial spores resulting from differences in DNA extraction efficiencies.
    Mestvergisting Fermtech systems en Ecobag
    Kasper, G.J. ; Kemperman, A.J.M. - \ 2015
    Wageningen : Wageningen UR Livestock Research (Rapport / Wageningen UR Livestock Research 874) - 45
    mestvergisting - melkveehouderij - biogas - voedingsstoffen - dierlijke meststoffen - systeeminnovatie - bioraffinage - duurzaamheid (sustainability) - fermentatie - biobased economy - manure fermentation - dairy farming - biogas - nutrients - animal manures - system innovation - biorefinery - sustainability - fermentation - biobased economy
    Een deel van de veehouders wil de energetische waarde van mest benutten om in hun energieverbruik te voorzien. Vergisting is een methode om energie uit mest te halen. Doel is het vergisten van alle soorten dierlijke mest met systemen die een rendabele business case realiseren in de keten ‘(verse) mest tot en met verwaarden van digestaat of mineralenterugwinning m.b.v. mestraffinage’. Hiertoe zijn twee innovatieve technieken van vergisten onderzocht, die op pilotschaal zijn getest. Daarna zal bij opschaling het innovatieve vergistingsproces van grote betekenis kunnen zijn voor het mede oplossen van het Nederlandse mestprobleem. Het doel van dit project in engere zin beperkt zich tot het monitoren van alleen de innovatieve vergistingstechnieken van twee systemen met melkveemest op boerderijschaal.
    Impacts of NF concentrate recirculation on membrane performance in an integrated MBR and NF membrane process for wastewater treatment
    Kappel, C. ; Kemperman, A.J.B. ; Temmink, B.G. ; Zwijnenburg, A. ; Rijnaarts, H. ; Nijmeijer, K. - \ 2014
    Journal of Membrane Science 453 (2014). - ISSN 0376-7388 - p. 359 - 368.
    natural organic-matter - nanofiltration membranes - activated-sludge - treatment plants - heavy-metals - bioreactor - retention - acids
    As water shortages are increasing, the need for sustainable water treatment and the reuse of water is essential. Water reuse from wastewater can be accomplished in a membrane bioreactor (MBR) in the secondary activated sludge stage of a wastewater treatment plant. To remove viruses, dissolved organics and inorganics still present in the MBR permeate, nanofiltration (NF) can be applied. Nevertheless, the major drawback of nanofiltration membranes is the production of a concentrate stream that cannot be discharged to the environment. In this research we investigate the concept of a combined MBR and NF system with NF concentrate recirculation back to the MBR to produce reusable water in a sustainable way. Long-term continuous operation (1 year) shows that the NF permeate quality is riot impacted by the recirculation. Fouling on the NF membrane is mostly the result of inorganics, while organics (e.g. humic acids) do not have a major impact on NF fouling. In fact, the flux of the NF was enhanced by the presence of humic acids due to recirculation. However, the MBR showed increased fouling and consequently more frequent membrane cleaning. The results presented show that the continuous production of reusable water from wastewater in a combined MBR and NO process with NO concentrate recirculation can be successful. (C) 2013 Elsevier B.V. All rights reserved
    Effect of dissolved oxygen concentration on the bioflocculation process in high loaded MBRs
    Faust, L. ; Temmink, B.G. ; Zwijnenburg, A. ; Kemperman, A.J.B. ; Rijnaarts, H. - \ 2014
    Water Research 66 (2014). - ISSN 0043-1354 - p. 199 - 207.
    afvalwaterbehandeling - uitvlokking - bioreactoren - waste water treatment - flocculation - bioreactors - waste-water treatment - extracellular polymeric substances - activated-sludge flocs - improved energy recovery - membrane bioreactor - size distribution - biofilm structure - stability - sewage - performance
    High-loaded membrane bioreactors (HL-MBRs), i.e. MBRs which are operated at extremely short sludge and hydraulic retention times, can be applied to flocculate and concentrate sewage organic matter. The concentrated organics can be used for energy recovery, or for the production of more valuable organic chemicals. Little is known about the effect of the dissolved oxygen concentration (DO) on this bioflocculation process. To examine this effect, two HL-MBRs were operated, respectively at a low (1 mg L-1) and a higher (4 mg L-1) DO. The higher DO resulted in a better flocculation efficiency, i.e. 92% of the colloidal COD in the sewage flocculated compared to 69% at the lower DO. The difference was attributed to a higher microbial production of extracellular polymeric substances at a DO of 4 mg L-1 and to more multivalent cations (calcium, iron and aluminium) being distributed to the floc matrix. In addition, the HL-MBR that was operated at a DO of 4 mg L-1 gave a bigger mean floc size, a lower supernatant turbidity, better settleability and better membrane filterability than the HL-MBR that was operated at a DO of 1 mg L-1.
    High loaded MBRs for organic matter recovery from sewage: Effect of solids retention time on bioflocculation and on the role of extracellular polymers
    Faust, L. ; Temmink, B.G. ; Zwijnenburg, A. ; Kemperman, A.J.B. ; Rijnaarts, H. - \ 2014
    Water Research 56 (2014). - ISSN 0043-1354 - p. 258 - 266.
    waterzuivering - membranen - biofilms - organische stof - water treatment - membranes - biofilms - organic matter - municipal waste-water - submerged membrane bioreactor - improved energy recovery - activated-sludge process - microbial community - surface-properties - substances eps - performance - extraction - constituents
    High loaded MBRs (HL-MBR) can concentrate sewage organic matter by aerobic bioflocculation for subsequent anaerobic conversion to methane or volatile fatty acids. In the range of very short solid retention times (SRT), the effect of SRT on bioflocculation and EPS production in HL-MBR was investigated. This short SRT range was selected to find an optimum SRT maximising recovery of organics by aerobic bioflocculation and minimizing losses of organics by aerobic mineralization. Bioflocculation was studied in five HL-MBRs operated at SRTs of 0.125, 0.25, 0.5, 1 and 5 d. The extent of flocculation, defined as the fraction of suspended COD in the concentrate, increased from 59% at an SRT of 0.125 d to 98% at an SRT of 5 d. The loss of sewage organic matter by biological oxidation was 1, 2, 4, 11 and 32% at SRT of 0.125–5 d. An SRT of 0.5–1 d gave best combination of bioflocculation and organic matter recovery. Bound extracellular polymeric substances (EPS) concentrations, in particular EPS-protein concentrations, increased when the SRT was prolonged from 0.125 to 1 d. This suggests that these EPS-proteins govern the bioflocculation process. A redistribution took place from free (supernatant) EPS to bound (floc associated) EPS when the SRT was prolonged from 0.125 to 1 d, further supporting the fact that the EPS play a dominant role in the flocculation process. Membrane fouling was most severe at the shortest SRTs of 0.125 d. No positive correlation was detected between the concentration of free EPS and membrane fouling, but the concentration of submicron (45–450 nm) particles proved to be a good indicator for this fouling.
    Population-based nutrikinetic modelling of phytochemical exposure
    Velzen, E.J.J. van; Westerhuis, J.A. ; Grün, C.H. ; Duynhoven, J.P.M. van; Jacobs, D.M. ; Eilers, P.H.C. ; Mulder, T.P. ; Foltz, M. ; Garczarek, U. ; Kemperman, R. ; Vaughan, E.E. ; Smilde, A.K. - \ 2014
    Metabolomics 10 (2014)6. - ISSN 1573-3882 - p. 1059 - 1073.
    red wine/grape juice - black tea - dietary polyphenols - phenolic metabolites - nutrition research - food sources - human plasma - green tea - gut model - pharmacokinetics
    The beneficial health effects of fruits and vegetables have been attributed to their polyphenol content. These compounds undergo many bioconversions in the body. Modeling polyphenol exposure of humans upon intake is a prerequisite for understanding the modulating effect of the food matrix and the colonic microbiome. This modeling is not a trivial task and requires a careful integration of measuring techniques, modeling methods and experimental design. Moreover, both at the population level as well as the individual level polyphenol exposure has to be quantified and assessed. We developed a strategy to quantify polyphenol exposure based on the concept of nutrikinetics in combination with population-based modeling. The key idea of the strategy is to derive nutrikinetic model parameters that summarize all information of the polyphenol exposure at both individual and population level. This is illustrated by a placebo-controlled crossover study in which an extract of wine/grapes and black tea solids was administered to twenty subjects. We show that urinary and plasma nutrikinetic time-response curves can be used for phenotyping the gut microbial bioconversion capacity of individuals. Each individual harbours an intrinsic microbiota composition converting similar polyphenols from both test products in the same manner and stable over time. We demonstrate that this is a novel approach for associating the production of two gut-mediated ¿-valerolactones to specific gut phylotypes. The large inter-individual variation in nutrikinetics and ¿-valerolactones production indicated that gut microbial metabolism is an essential factor in polyphenol exposure and related potential health benefits
    Electrochemical phosphate recovery from nanofiltration concentrates
    Kappel, C. ; Yasadi, K. ; Temmink, B.G. ; Metz, S.J. ; Kemperman, A.J.B. ; Nijmeijer, K. ; Zwijnenburg, A. ; Witkamp, G.J. ; Rijnaarts, H. - \ 2013
    Separation and Purification Technology 120 (2013). - ISSN 1383-5866 - p. 437 - 444.
    amorphous calcium-phosphate - municipal waste-water - aqueous-solution - precipitation - hydroxyapatite - magnesium - struvite - removal - substitution - experiences
    The high total phosphorus content of raw domestic wastewater with its significant eutrophication potential offers an excellent possibility for phosphate recovery. Continuous recirculation of NF concentrate to an MBR and simultaneous phosphate recovery from the NF concentrate can be applied to produce reusable water, recovering phosphates, while at the same time decreasing the scaling potential of the recirculated NF concentrate, prolonging the retention times of slowly biodegradable soluble compounds (e.g. micropollutants) and recirculating multivalent cations to promote the bio-flocculation. Here we introduce an electrochemical system to recover phosphates. An electrochemical cell was divided into an anode and a cathode compartment separated by a cation exchange membrane. Precipitation of phosphates from nanofiltration concentrate was induced by locally increasing the pH at the cathode surface by water electrolysis and thereby creating supersaturated conditions at the cathode. 70–95% recovery of total phosphate was achieved at a pH of 8–10 near the cathode. Ion analysis, XRD and ATR-FTIR spectra indicated that the precipitate consisted of amorphous calcium phosphate (ACP) and minor proportions of amorphous calcium carbonate (ACC). The amount of ACC was dependent on the pH. Calcium phosphate scaling at the cathode surface did not occur due to H2-gas formation preventing nucleation and growth at the cathode.
    Evaluation and optimization of bar-coded amplicon sequencing for the characterization of spoilage microbiota in food products
    Boer, P. de; Caspers, M.P.M. ; Sanders, J.W. ; Kemperman, R. ; Wijman, J. ; Lommerse, G. ; Roeselaars, G. ; Montijn, R. ; Abee, T. ; Kort, R. - \ 2013
    In: Microbials Spoilers in Food 2013. - Quimper : - p. 45 - 45.
    Influence of membrane properties on fouling in submerged membrane bioreactors
    Marel, P. van der; Zwijnenburg, A. ; Kemperman, A. ; Wessling, M. ; Temmink, B.G. ; Meer, W. van der - \ 2010
    Journal of Membrane Science 348 (2010)1-2. - ISSN 0376-7388 - p. 66 - 74.
    waste-water treatment - cross-flow microfiltration - subcritical flux operation - activated-sludge - step method - filtration - ultrafiltration - deposition - morphology - colloids
    Polymeric flat-sheet membranes with different properties were used in filtration experiments with activated sludge from a pilot-scale MBR to investigate the influence of membrane pore size, surface porosity, pore morphology, and hydrophobicity on membrane fouling. An improved flux-step method was used to measure both the critical flux and critical flux for irreversibility. Long term experiments were performed to evaluate if influences of membrane properties on short term could be translated to long term fouling behavior. The results showed that a hydrophilic asymmetric membrane with an interconnected pore structure, a nominal pore size of 0.3 µm, and large surface porosity of 27%, provided the best membrane performance with respect to critical flux and critical flux for irreversibility. The dominant fouling mechanism in long term filtration experiments was gel layer formation, which for this membrane was the least severe, and therefore extended the sustainable time.
    An improved flux-step method to determine the critical flux and the critical flux for irreversibility in a membrane bioreactor
    Marel, P. van der; Zwijnenburg, A. ; Kemperman, A. ; Wessling, M. ; Temmink, B.G. ; Meer, W. van der - \ 2009
    Journal of Membrane Science 332 (2009)1-2. - ISSN 0376-7388 - p. 24 - 29.
    waste-water treatment - cross-flow microfiltration - filtration - ultrafiltration - suspensions - operation
    An improved flux-step method is presented incorporating cleaning steps by relaxation to determine the critical flux and the critical flux for irreversibility. Experiments are performed with activated sludge fed with real municipal wastewater. The improved flux-step method is compared with a common flux-step method often used in the literature. The critical flux for a polyvinylidenefluoride flat-sheet membrane with a pore size of 0.1 µm is 56 ± 2 L m-2 h-1 according to the common flux-step method and 52 ± 3 L m-2 h-1 according to the improved flux-step method. The marginal difference is explained by the application of larger flux-steps in the improved flux-step method. By applying intermediate relaxation the fouling appears to be almost completely reversible, indicating that cake layer formation is the dominant fouling mechanism. The cake layer remains removable up to a flux of 100 L m-2 h-1. The critical flux for irreversibility is therefore larger than 100 L m-2 h-1. The influence of fouling history is reduced by intermediate relaxation. As a result, the total fouling rate is much lower with the improved flux-step method compared to the common flux-step method, showing almost no fouling rate hysteresis in the improved method. A low amount of irreversible fouling is measured due to the adsorption of macromolecules, pore blocking, and/or gel formation. Applying the improved method ten times consecutively shows the influence of irreversible fouling on the long term. The critical flux decreases by 4 L m-2 h-1 as a consequence of irreversible fouling during the ten runs representing a long filtration run of 150 h at a net flux of 19 L m-2 h-1
    State Capture, Income and Institutional Quality
    Lensink, B.W. ; Kemperman, M. - \ 2008
    Applied Economics Letters 15 (2008)6. - ISSN 1350-4851 - p. 423 - 426.
    economic-development
    This article argues that the impact of income on institutional quality depends on state capture, and that a rise in income contributes to institutional development only if the degree of state capture is low.
    In situ product removal during enzymatic cephalexin synthesis by complexation
    Schroën, C.G.P.H. ; Nierstrasz, V.A. ; Bosma, R. ; Kemperman, G.J. ; Strubel, M. ; Ooijkaas, L.P. ; Beeftink, H.H. ; Tramper, J. - \ 2002
    Enzyme and Microbial Technology 31 (2002). - ISSN 0141-0229 - p. 264 - 273.
    In this paper, `complexation' indicates the formation of clathrate type inclusion compounds of cephalexin with naphthalene derivatives. These inclusion compounds readily crystallise in solution, resulting in specific co-crystals of complexing agent and cephalexin with a set ratio between both components. Complexation is used for in situ product removal during enzymatic kinetic cephalexin synthesis to prevent undesired hydrolysis. In order to achieve this, beneficial reaction conditions have to be matched with conditions that are beneficial for complexation. In the work described here, a pH of 7.5 and a temperature of 293 K meet these requirements best. The results were compared to predictions obtained with a model originally developed for cephalexin synthesis and which is now extended with complexation. For 1,5-dihydroxy-naphthalene, the course of the reaction was predicted accurately. For 2-naphthol, this was not the case; synthesis was enhanced and hydrolysis reduced compared to the model predictions for immobilised enzyme. On the other hand, the course of reactions could be predicted accurately by the model for liquid enzyme. Apparently, the reduced reaction rate (~30 esidual activity) is such that mass transfer can keep up with it and diffusion limitation was lifted resulting in higher cephalexin concentrations. The effect of in situ complexation on productivity is discussed. It was found that complexation has a beneficial effect on overall cephalexin productivity and in most cases, hydrolysis is suppressed. The effects were most pronounced for liquid enzyme in combination with complexation with 1,5-dihydroxy-naphthalene for which, also experimentally, the highest cephalexin concentrations were measured.
    Complexants for the clathration mediated synthesis of the antibiotic cephradine
    Kemperman, G.J. ; Gelder, R. de; Dommerholt, F.J. ; Schroën, C.G.P.H. ; Bosma, R. ; Zwanenburg, B. - \ 2001
    Green Chemistry 3 (2001). - ISSN 1463-9262 - p. 189 - 192.
    Enzymatic synthesis of cephalosporins is hampered by secondary hydrolysis and by complicated down-stream processing. Instantaneous removal of cephalosporin product by clathration, using an efficient and selective complexing agent, offers an attractive opportunity to tackle these problems. A series of benzene derivatives that form clathrate-type complexes with the cephalosporin antibiotics was subjected to efficiency measurements with Cephradine and enzyme inhibition studies. The best results for the antibiotic Cephradine were obtained with methyl 2-aminobenzoate, 2-hydroxybiphenyl and methyl 4-hydroxybenzoate. These three compounds are environmentally and toxicologically fully acceptable for application in a 'green' process.
    Interfacially polymerized layers for the stabilization of supported liquid membranes
    Kemperman, A.J.B. ; Boomgaard, Th. van den; Strathmann, H. - \ 1995
    In: Proceedings of Euromembrane '95, volume 1: 1-250-255
    Stabilization of supported liquid membranes
    Kemperman, A.J.B. - \ 1995
    University of Twente. -
    Perspectieven voor landbouw en ruimte, een case-study voor Zuid-Oost Friesland.
    Hidding, M.C. ; Hoorn, A.S. ; Kemperman, A.J.M. - \ 1993
    Wageningen : Vg. Ruimtelijke Planvorming LU Wageningen (Bedrijfsstijlenstudie 10.3) - 73 p.
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