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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    Doubling of Microalgae Productivity by Oxygen Balanced Mixotrophy
    Abiusi, Fabian ; Wijffels, Rene H. ; Janssen, Marcel - \ 2020
    ACS sustainable chemistry & engineering 8 (2020)15. - ISSN 2168-0485 - p. 6065 - 6074.
    Biomass yield on substrate - Carbon balance - Microalgae productivity - Mixotrophic cultivation - Oxygen balance

    Microalgae productivity was doubled by designing an innovative mixotrophic cultivation strategy that does not require gas-liquid transfer of oxygen or carbon dioxide. Chlorella sorokiniana SAG 211/8K was cultivated under continuous operation in a 2 L stirred-tank photobioreactor redesigned so that respiratory oxygen consumption was controlled by tuning the acetic acid supply. In this mixotrophic setup, the reactor was first operated with aeration and no net oxygen production was measured at a fixed acetic acid supply rate. Then, the aeration was stopped and the acetic acid supply rate was automatically regulated to maintain a constant dissolved oxygen level using process control software. Respiratory oxygen consumption was balanced by phototrophic oxygen production, and the reactor was operated without any gas-liquid exchange. The carbon dioxide required for photosynthesis was completely provided by the aerobic conversion of acetic acid. Under this condition, the biomass/substrate yield was 0.94 C-molx·C-molS -1. Under chemostat conditions, both reactor productivity and algal biomass concentration were doubled in comparison to a photoautotrophic reference culture. Mixotrophic cultivation did not affect the photosystem II maximum quantum yield (Fv/Fm) and the average-dry-weight-specific optical cross section of the microalgal cells. Only light absorption by chlorophylls over carotenoids decreased by 9% in the mixotrophic culture in comparison to the photoautotrophic reference. Our results demonstrate that photoautotrophic and chemoorganotrophic metabolism operate concurrently and that the overall yield is the sum of the two metabolic modes. At the expense of supplying an organic carbon source, photobioreactor productivity can be doubled while avoiding energy intensive aeration.

    Habitatrichtlijnrapportage 2019: Annex D Habitattypen : Achtergronddocument
    Janssen, John ; Bijlsma, Rienk-Jan ; Arts, Gertie ; Baptist, Martin ; Hennekens, Stephan ; Knegt, Bart de; Meij, Tom van der; Schaminée, Joop ; Strien, Arco van; Wijnhoven, Sander ; Ysebaert, Tom - \ 2020
    Wageningen : Wettelijke Onderzoekstaken Natuur & Milieu (WOt-technical report 171) - 97
    This document describes the concepts, data and methods used in the 2019 report (under Article 17 of the Habitats Directive) on the conservation status of habitat types for the parameters range, area, structure and functions, and future prospects. The ranges of nearly all habitat types have not changed. No reliable, updated data on area were available for most habitat types. The methodology for assessing structure and functions has been thoroughly revised to accommodate long-term monitoring data and meet the new reporting formats. The European Commission has also introduced a new method for assessing future prospects. The report presents the results and indicates where the methods and data can be improved.
    Alien flora across European coastal dunes
    Giulio, Silvia ; Acosta, Alicia Teresa Rosario ; Carboni, Marta ; Campos, Juan Antonio ; Chytrý, Milan ; Loidi, Javier ; Pergl, Jan ; Pyšek, Petr ; Isermann, Maike ; Janssen, John A.M. ; Rodwell, John S. ; Schaminée, Joop H.J. ; Marcenò, Corrado - \ 2020
    Applied Vegetation Science (2020). - ISSN 1402-2001
    alien flora - Atlantic - Baltic - Black Sea - coastal dune habitats - Mediterranean - neophyte - non-native - plant invasion - vegetation-plot data

    Questions: The spread of alien plant species is one of the main threats to the biodiversity of different natural habitats, and coastal dune habitats are among the most affected. There is a considerable local and regional variation in the level of alien plant invasion on coastal dunes. We asked what are the patterns of invasion across European coastal dunes and how they depend on habitat types and coastal regions. Location: Atlantic, Baltic, Black Sea and Mediterranean coasts of Europe. Methods: We used vegetation-plot records from shifting dunes and stable dune grasslands extracted from the European Vegetation Archive (EVA). We quantified richness, frequency and distribution of alien plant (neophyte) species across dune habitats and coastal regions. We also explored the donor habitats and invasion trajectories of these species. Results: In the flora of European coastal dunes, 7% of species were neophytes, for two-thirds originating from outside of Europe and mostly naturalised and ruderal. Shifting and stable dunes were similar in neophyte species composition, but there were more individual occurrences of neophytes in shifting dunes. The neophyte flora composition differed considerably between the Atlantic, Baltic, Black Sea and Mediterranean regions. The highest number of neophyte species was observed on the Atlantic dunes, while the highest number of neophyte occurrences was on the Black Sea dunes. Most of the neophytes originated from North America and the Mediterranean-Turanian region. Erigeron canadensis, Xanthium orientale, Oenothera biennis and Oenothera oakesiana were the most common neophytes. Conclusions: We provided a comprehensive assessment of alien plant invasions in the coastal dunes across Europe and highlighted that coastal dunes should be in the focus of European invasion management strategies.

    Vogel- en Habitatrichtlijnrapportage 2019
    Adams, Annemiek ; Bijlsma, Rienk-Jan ; Bos, Gerdien ; Clerkx, Sandra ; Janssen, John ; Kleunen, André van; Remmelts, Wilmar ; Rooijen, Nils van; Schaminée, Joop ; Schmidt, Anne ; Swaay, Chris van; Wijnhoven, Sander ; Woestenburg, Martin ; Aar, Mies van - \ 2020
    Wageningen : Wettelijke Onderzoekstaken Natuur & Milieu (Thema Informatievoorziening Natuur / Wettelijke Onderzoekstaken Natuur & Milieu ) - 52
    Maximization of sulfur formation in the presence of organic sulfur compounds in a dual bioreactor gas desulfurization system
    Kiragosyan, Karine - \ 2020
    Wageningen University. Promotor(en): A.J.H. Janssen, co-promotor(en): P. Roman; J.B.M. Klok. - Wageningen : Wageningen University - ISBN 9789463952583 - 180

    The growth of the global population and its associated increased demands for energy, food, and water has resulted in the intensification of industry and land use and hence loss of biodiversity and climate change. The overuse of natural resources, anthropogenic gas emissions and wastewater discharges into open waters cause environmental pollution, which, as a chain reaction, trigger  changes in the natural habitats of flora and fauna. Moreover, accumulation of CO2, N2O, CH4 and SO2 gases in the atmosphere cause health problems for millions of people and accelerate climate change.

    To sustain a global population of 7.7 billion people and manage their environmental footprint sustainably, the industry should transition towards a circular economy by using renewable resources and implementation of sustainable technologies. One such technology is the gas biodesulfurization process developed by our group in the Department of Environmental Technology at Wageningen University in cooperation with Delft University of Technology, University of Amsterdam, and industrial partners: Paqell B.V, Paques B.V and Shell. This technology emerged in the early 1990s when physicochemical desulfurization processes were dominating the market. Our biodesulfurization technology distinguishes itself because of its reduced operational and capital expenditures, and smaller environmental footprint. Since then, gas biodesulfurization has been intensively studied in order to facilitate higher sulfur recovery rates (>90 mol%) and stable process operations while treating a variety of gas feed streams. A high selectivity for sulfur is preferred because this will regenerate hydroxide ions, which are consumed when H2S is removed from gas streams. In addition, the consumption of air, energy, and caustic at sulfur-producing conditions are lower relative to the formation of sulfuric acid. Furthermore, the recovered sulfur slurry can be used as fertilizer and as fungicide. To maintain a stable sulfur selectivity, the biodesulfurization process operation should remain stable as well, especially when gas feed composition and sulfide concentration fluctuate. The composition of the feed gas depends on the industry that generates the sour gas. For example, biogas formed from the anaerobic digestion of wastewater in paper mill facilities has a relatively low amount of H2S (0.7 vol.%), whereas sour gas streams in the oil and gas industry are composed of up to 95 vol.% of H2S, a fraction of CO2, hydrocarbons, and thiols. The H2S concentration can vary greatly, not only between industries but also during the operation of a single installation. The daily H2S loading rate between Thiopaq installations may range from 10 kg day-1 up to 150 ton day-1. Therefore, the aim of this research was to achieve more sulfur formation and stable process operation in the presence of thiols.

    Messelink, Gerben J. ; Calvo, F.J. ; Marín, Francisco ; Janssen, Dirk - \ 2020
    In: Integrated Pest and Disease Management in Greenhouse Crops / Gullino, Maria Lodovica, Albajes, Ramon, Nicot, Philippe C., Springer International Publishing - ISBN 9783030223038 - p. 537 - 566.
    Several cucurbits species are cultivated in greenhouses worldwide. The most important genera are (1) Cucurbita, which includes squash, pumpkin, zucchini and gourds, (2) Citrullus, which includes watermelon and (3) Cucumis, which includes cucumber and various melons. Pests and diseases affecting cucurbit crops can vary considerably in relation to geographic area and cropping system. Growing in soil or on hydroponics strongly determines the presence of certain soil pathogens or nematodes. Also the way the crop is cultivated, the number of cropping cycles and the transition between cycles strongly affects the performance of pests, diseases and biological control agents. The main pests and diseases detrimental to cucurbits in various parts of the globe are reported here, along with the most effective or sustainable control strategies currently applied to manage them. Many pests can be controlled very successfully with natural enemies, but despite the recent developments on microbiological control agents, integrated pest management (IPM) with a low input of pesticides and, particularly fungicides, remains challenging in cucurbits, mainly because of viruses and diseases that are difficult to manage biologically or with selective control methods. Plant breeding programmes that develop disease tolerant cultivars that can be combined with arthropod natural enemies for pest control are promising to further develop robust IPM systems for cucurbits.
    Bioenergetics of peripheral blood mononuclear cells from endurance-trained and untrained healthy young adults analysed using extracellular flux assays
    Janssen, J.J.E. ; Lagerwaard, B. ; Nieuwenhuizen, A.G. ; Keijer, J. ; Boer, V.C.J. de - \ 2020
    In: Wias Annual Conference 2020 WIAS - p. 68 - 68.
    Skeletal muscle mitochondrial amount and function is positively affected by endurance exercise and training status1. However, to routinely assess mitochondrial function in response to exercise in humans, practical and non-invasive measurements of mitochondrial function are needed. We used near-infrared spectroscopy as a non-invasive method to assess the effect of training status on in vivo mitochondrial function2.In addition, we study peripheral blood mono nuclear cells (PBMCs), since PBMCs are relatively easily obtained from individuals and the immune system is involved in regulating the response of the body to exercise. Therefore we optimized and validated bright field imaging coupled to extracellular flux measurements in PBMCs to study the effect of training status on bioenergetic PBMC profiles. Methods. Extracellular flux measurements were performed using the Seahorse XFe Analyzer. For validation of our novel imaging approach in analyzing PBMC bio energetics, PBMCs were isolated from human buffy coats obtained from healthy blood donors and plated on coated Seahorse XFe96 cell culture microplates (0.5 – 3.0 x 105 cells/well). Brightfield images were taken using Cytation 1 and analyzed using ImagePro and ImageJ software. To study the effect of training status on bioenergetic PBMC profiles, eight endurance-trained (VO2max >57 ml/kg/min) and eight untrained(VO2max <47 ml/kg/min) young male adults were included. Results and conclusions Linear relationships were identified between plated cell number and pixel number (R2 = 0.9834,P < 0.001) and between calculated cell number (based on pixel number) and basal oxygen consumption rate (OCR) (R2 = 0.9491, P < 0.001) in multiple buffy coats, demonstrating reproducibility and suitability of our method for analyzing mitochondrial function in PBMCs over different days over a wide cell number range. Findings from our human trial on endurance-trained individuals indicated that PBMCs from endurance-trained individuals showed significantly lower coupling efficiency values (P = 0.0289) as well as higher proton leak compared to untrained individuals. No differences in basal respiratory OCR, maximal respiratory OCR or spare respiratory capacity in PBMCs from endurance-trained and untrained individuals were observed (P > 0.05). Our findings reveal a possible lower ATP production capacity of PBMCs from endurance-trained individuals and could contribute to further understanding how PBMC bioenergetics contribute to immune function and whole body performance.
    Fish Macrophages Show Distinct Metabolic Signatures Upon Polarization
    Wentzel, Annelieke S. ; Janssen, Joëlle J.E. ; Boer, Vincent C.J. de; Veen, Wouter G. van; Forlenza, Maria ; Wiegertjes, Geert F. - \ 2020
    Frontiers in Immunology 11 (2020). - ISSN 1664-3224 - 1 p.
    extracellular flux analysis - glycolysis - M1 M2 macrophage polarization - metabolic reprogramming - oxidative metabolism - oxidative phosphorylation (OXPHOS) - Seahorse - teleost

    Macrophages play important roles in conditions ranging from host immune defense to tissue regeneration and polarize their functional phenotype accordingly. Next to differences in the use of L-arginine and the production of different cytokines, inflammatory M1 macrophages and anti-inflammatory M2 macrophages are also metabolically distinct. In mammals, M1 macrophages show metabolic reprogramming toward glycolysis, while M2 macrophages rely on oxidative phosphorylation to generate energy. The presence of polarized functional immune phenotypes conserved from mammals to fish led us to hypothesize that a similar metabolic reprogramming in polarized macrophages exists in carp. We studied mitochondrial function of M1 and M2 carp macrophages under basal and stressed conditions to determine oxidative capacity by real-time measurements of oxygen consumption and glycolytic capacity by measuring lactate-based acidification. In M1 macrophages, we found increased nitric oxide production and irg1 expression in addition to altered oxidative phosphorylation and glycolysis. In M2 macrophages, we found increased arginase activity, and both oxidative phosphorylation and glycolysis were similar to control macrophages. These results indicate that M1 and M2 carp macrophages show distinct metabolic signatures and indicate that metabolic reprogramming may occur in carp M1 macrophages. This immunometabolic reprogramming likely supports the inflammatory phenotype of polarized macrophages in teleost fish such as carp, similar to what has been shown in mammals.

    Elevated viscosities in a simulated moving bed for γ-aminobutyric acid recovery
    Schultze-Jena, A. ; Boon, M.A. ; Vroon, R.C. ; Bussmann, P.J.Th. ; Janssen, A.E.M. ; Padt, A. van der - \ 2020
    Journal of Separation Science 43 (2020)7. - ISSN 1615-9306 - p. 1256 - 1264.
    chromatography - concentration profile - productivity - simulated moving bed - viscosity

    Process streams of agro-food industries are often large and viscous. In order to fractionate such a stream the viscosity can be reduced by either a high temperature or dilution, the former is not an option in case of temperature sensitive components. Such streams are diluted prior to chromatographic fractionation, resulting in even larger volumes and high energy costs for sub-sequential water removal. The influence of feed viscosity on the performance of simulated moving bed chromatography has been investigated in a case study of the recovery of a γ-aminobutyric acid rich fraction from tomato serum. This work addresses the chromatographic system design, evaluates results from a pilot scale operation, and uses these to calculate the productivity and water use at elevated feed concentration. At the two higher feed viscosities (2.5 and 4 mPa·s) water use is lower and productivity higher, compared to the lowest feed viscosity (1 mPa·s). The behavior of the sugars for different feed viscosities can be described well by the model using the ratio of feed to eluent as dilution factor. The behavior of γ-aminobutyric acid is highly concentration dependent and the recovery could not be accurately predicted.

    The economic value of R0 for selective breeding against microparasitic diseases
    Janssen, Kasper ; Bijma, Piter - \ 2020
    Genetics, Selection, Evolution 52 (2020)1. - ISSN 0999-193X - 1 p.

    BACKGROUND: Microparasitic diseases are caused by bacteria and viruses. Genetic improvement of resistance to microparasitic diseases in breeding programs is desirable and should aim at reducing the basic reproduction ratio [Formula: see text]. Recently, we developed a method to derive the economic value of [Formula: see text] for macroparasitic diseases. In epidemiological models for microparasitic diseases, an animal's disease status is treated as infected or not infected, resulting in a definition of [Formula: see text] that differs from that for macroparasitic diseases. Here, we extend the method for the derivation of the economic value of [Formula: see text] to microparasitic diseases. METHODS: When [Formula: see text], the economic value of [Formula: see text] is zero because the disease is very rare. When [Formula: see text]. is higher than 1, genetic improvement of [Formula: see text] can reduce expenditures on vaccination if vaccination induces herd immunity, or it can reduce production losses due to disease. When vaccination is used to achieve herd immunity, expenditures are proportional to the critical vaccination coverage, which decreases with [Formula: see text]. The effect of [Formula: see text] on losses is considered separately for epidemic and endemic disease. Losses for epidemic diseases are proportional to the probability and size of major epidemics. Losses for endemic diseases are proportional to the infected fraction of the population at the endemic equilibrium. RESULTS: When genetic improvement reduces expenditures on vaccination, expenditures decrease with [Formula: see text] at an increasing rate. When genetic improvement reduces losses in epidemic or endemic diseases, losses decrease with [Formula: see text] at an increasing rate. Hence, in all cases, the economic value of [Formula: see text] increases as [Formula: see text] decreases towards 1. DISCUSSION: [Formula: see text] and its economic value are more informative for potential benefits of genetic improvement than heritability estimates for survival after a disease challenge. In livestock, the potential for genetic improvement is small for epidemic microparasitic diseases, where disease control measures limit possibilities for phenotyping. This is not an issue in aquaculture, where controlled challenge tests are performed in dedicated facilities. If genetic evaluations include infectivity, genetic gain in [Formula: see text] can be accelerated but this would require different testing designs. CONCLUSIONS: When [Formula: see text], its economic value is zero. The economic value of [Formula: see text] is highest at low values of [Formula: see text] and approaches zero at high values of [Formula: see text].

    Geschiktheid zeewindparken voor maricultuur en passieve visserij : een kwantitatieve beoordeling van de kansrijkheid van de gebieden voor de potentiële productiviteit van een selectie aan commercieel interessante soorten
    Bogaart, Lisanne van den; Wal, Jan Tjalling van der; Tonk, Linda ; Bos, Oscar ; Coolen, Joop ; Poelman, Marnix ; Vergouwen, Sophie ; Duren, Luca van; Janssen, Henrice ; Timmermans, Klaas - \ 2020
    Yerseke : Wageningen Marine Research (Wageningen Marine Research report C127/19A) - 111
    In de Nederlandse Exclusieve Economische Zone (EEZ) zijn windparken gepland op diverse locaties. Door de windparken ontstaan nieuwe kansen voor multifunctioneel gebruik zoals maricultuur en niet-bodemberoerende visserij met passieve vistuigen. Deze studie brengt de potentiële - kwantitatieve - productiviteit van het kweken of vissen (passief vistuig) binnen bestaande, geplande en mogelijke toekomstige windparklocaties op de Noordzee in kaart voor een aantal vormen van medegebruik; kweek van bepaalde soorten zeewier en schelpdieren en de niet-bodemberoerende vangst van bepaalde soorten vissen, schaaldieren en inktvissen. Dit project is een vervolg op een voorgaand project waarbij een kwalitatieve beoordeling gegeven is van de kansrijkheid van de gebieden. In de huidige studie is voor een selectie van kansrijke soorten een berekening voor oogst of productie uitgevoerd. Daarnaast is dit rapport bedoeld om op basis van de huidige stand van kennis een inschatting te geven van de orde van grootte van het ruimtebeslag van zeewierproductie binnen toekomstige windparken. Met een aantal berekeningen wordt inzicht gegeven in de orde van grootte van opbrengsten, beschikbare/benodigde oppervlakten en benodigde nutriënten in de Noordzee. Op basis van deze analyse lijkt een areaal van enkele honderden km2 zeewierproductie realistisch, hierbij is uitgegaan van een grove indicatieve berekening, met diverse aannames. Op basis van de beschikbare voedingsstoffen voor mosselen zou tussen ca. 50 en 100 ton drooggewicht mosselen per km2 per jaar kunnen worden geproduceerd, waarbij de bronnen van onzekerheid in acht genomen dienen te worden. Om een indruk te krijgen van het (relatieve) voorkomen van vissen, weekdieren en schaaldieren is gebruik gemaakt van VMS- en logboekgegevens samen met gegevens van twee jaarlijkse surveys (BTS en IBTS). Het is echter niet mogelijk gebleken om voor alle geselecteerde soorten een kwantitatieve inschatting te maken, aangezien er nog weinig bekend is over ruimtelijke verdeling van deze soorten. Daarom is voor deze soorten een overzicht gegeven van wat er in de literatuur over bekend is.
    Muscle Toxicity of Drugs: When Drugs Turn Physiology into Pathophysiology
    Janssen, Lando ; Allard, Neeltje A.E. ; Saris, Christiaan G.J. ; Keijer, Jaap ; Hopman, Maria T.E. ; Timmers, Silvie - \ 2020
    Physiological reviews 100 (2020)2. - p. 633 - 672.
    drug-induced myopathy - muscle toxicity - statin myopathy - statins

    Drugs are prescribed to manage or prevent symptoms and diseases, but may sometimes cause unexpected toxicity to muscles. The symptomatology and clinical manifestations of the myotoxic reaction can vary significantly between drugs and between patients on the same drug. This poses a challenge on how to recognize and prevent the occurrence of drug-induced muscle toxicity. The key to appropriate management of myotoxicity is prompt recognition that symptoms of patients may be drug related and to be aware that inter-individual differences in susceptibility to drug-induced toxicity exist. The most prevalent and well-documented drug class with unintended myotoxicity are the statins, but even today new classes of drugs with unintended myotoxicity are being discovered. This review will start off by explaining the principles of drug-induced myotoxicity and the different terminologies used to distinguish between grades of toxicity. The main part of the review will focus on the most important pathogenic mechanisms by which drugs can cause muscle toxicity, which will be exemplified by drugs with high risk of muscle toxicity. This will be done by providing information on key clinical and laboratory aspects, muscle electromyography patterns and biopsy results, and pathological mechanism and management for a specific drug from each pathogenic classification. In addition, rather new classes of drugs with unintended myotoxicity will be highlighted. Furthermore, we will explain why it is so difficult to diagnose drug-induced myotoxicity, and which tests can be used as a diagnostic aid. Lastly, a brief description will be given of how to manage and treat drug-induced myotoxicity.

    Time-dependent transcriptome profile of genes involved in triacylglycerol (TAG) and polyunsaturated fatty acid synthesis in Nannochloropsis gaditana during nitrogen starvation
    Janssen, Jorijn H. ; Spoelder, Jacco ; Koehorst, Jasper J. ; Schaap, Peter J. ; Wijffels, René H. ; Barbosa, Maria J. - \ 2020
    Journal of Applied Phycology 32 (2020). - ISSN 0921-8971 - p. 1153 - 1164.
    Microalgae - Nannochloropsis gaditana - Nitrogen starvation - Polyunsaturated fatty acids - Transcriptome - Triacylglycerol

    In this research, the gene expression of genes involved in lipid metabolism of the eustigmatophyte alga Nannochloropsis gaditana was measured by transcriptomic data. This microalga can be used as a source of triacylglycerol (TAG) and the omega-3 fatty acid eicosapentaenoic acid (EPA). Insight in TAG and EPA production and regulation are needed to improve their productivity. Nitrogen starvation induces TAG accumulation in N. gaditana. Previous research showed that during nitrogen starvation, EPA was translocated from the polar lipids to TAG and de novo synthesized in N. gaditana. Therefore, the expression levels of genes involved in fatty acid translocation and de novo TAG synthesis were measured. Furthermore, the genes involved in de novo EPA synthesis such as elongases and desaturases were studied. The expression levels were measured during the first hours of nitrogen starvation and the subsequent period of 14 days. One phospholipid:diacylglycerol acyltransferase (PDAT) gene involved in translocation of fatty acids from membrane lipids to TAG was upregulated. In addition, several lipases were upregulated, suggesting that these enzymes might be responsible for the translocation of EPA to TAG. Most desaturases and elongases involved in de novo EPA synthesis were downregulated during nitrogen starvation, except for Δ9 desaturase which was upregulated. This upregulation correlates with the increase in oleic acid. Due to the presence of many hypothetical genes, improvement in annotation is needed to increase our understanding of these pathways and their regulation.

    High viscosity preparative chromatography for food applications
    Schultze-Jena, A. ; Boon, M.A. ; Vroon, R.C. ; Bussmann, P.J.Th. ; Janssen, A.E.M. ; Padt, A. van der - \ 2020
    Separation and Purification Technology 237 (2020). - ISSN 1383-5866
    Food fractionation - Preparative chromatography - Productivity - System size - Viscosity

    The strength of chromatography lies in the ability of fine-tuning recovery for specific target components or fractions of interest. A downside of industrial chromatography is the need to dilute streams, as it is often applied today. This article challenges the conventional low concentration of input streams and investigates size exclusion chromatography at concentrated streams of high viscosity. Chromatographic operation with concentrated streams leads to an increased pressure drop over the column and decreased mass transfer kinetics, but also lower volumes compared to diluted streams. The objective of this research was to investigate separation performance and system dimensions as a function of viscosity for food type streams, in scenarios where viscosity is not caused by target components. Disadvantages due to increased stream volume with decreasing concentration and benefits due to decreased viscosity were evaluated, aiming to find minimal column volume. Separation performance was evaluated for a range of target components in a preparative lab-scale system using a size exclusion resin and mobile phase viscosities in the range of 1.2–8.7 mPa⋅s. Mobile phases were viscosified through addition of sucrose, glycerol, or dextran. Change in mass transfer resistance, measured via van Deemter curves, was related to the change in diffusivity through viscosity. The analysis of different viscosifying agents emphasized the influence of viscosity inside the pores, rather than viscosity of the bulk phase. The viscosity inside the pores was calculated via the partition coefficient of each viscosifying agent. Based on the slopes of van Deemter curves, column dimensions were calculated for different scenarios, assuming a non-compressible stationary phase. Column volume remained constant with stream dilution from 8.7 mPa⋅s down to about 2.5 mPa⋅s. However, at the same time column geometry changed to thinner and longer columns with decreasing viscosity, in order to accommodate throughput and pressure drop. When diluting to even lower viscosities, column volume increased, since stream viscosity is less sensitive to stream concentration at the low viscosity range. These results are relevant to a wide range of industries utilizing weak interaction chromatography, especially those where the main driver of process development is cost reduction and where a trade-off between purity, yield, and costs has to be made.

    Natuur Ambitie Grote Wateren Factsheet Vreugderijkerwaard
    Ottburg, F.G.W.A. ; Lammertsma, D.R. ; Maas, G.J. ; Janssen, J.A.M. ; Schotman, A.G.M. - \ 2020
    Wageningen University & Research - 3 p.

    Natuur Ambitie Grote Wateren Factsheet Cortenoever-Stokebrand
    Ottburg, F.G.W.A. ; Lammertsma, D.R. ; Maas, G.J. ; Janssen, J.A.M. ; Schotman, A.G.M. - \ 2020
    Wageningen University & Research - 3 p.
    Natuur Ambitie Grote Wateren (NAGW): evaluatie natuur binnen Ruimte voor de Rivier
    In het kader van ruimte voor de rivier zijn in het verleden meerdere maatregelen getroffen waaraan geen concrete ecologische doelen zijn gekoppeld. Om inzicht te krijgen in de ecologische effectiviteit ofwel welke natuurwaarden zijn er aanwezig, zijn in 2018 en 2019 een viertal maatregelen onderzocht. Het gaat hier om 1) het kwelmoeras in de Amerongse Bovenpolder, 2) de meestromende nevengeulen in de Vreugderijkerwaard, 3) twee geïsoleerde strangen in Cortenoever-Stokebrand en 4) ontsteende Kribvakken langs de IJssel nabij Zutphen. Naast vegetatie zijn zoetwatervissen, amfibieën, bevers, otters en vogels onderzocht. De eerste bevindingen zijn samenvattend weergegeven in de bijgaande drie pagina’s tellende factsheet per gebied.

    NAGW factsheet 1: Amerongse Bovenpolder.
    NAGW factsheet 2: Vreugderijkerwaard.
    NAGW factsheet 3: Cortenoever-Stokebrand.

    Fabrice Ottburg
    Natuur Ambitie Grote Wateren Factsheet Amerongse Bovenpolder
    Ottburg, F.G.W.A. ; Lammertsma, D.R. ; Maas, G.J. ; Janssen, J.A.M. ; Schotman, A.G.M. - \ 2020
    Wageningen University & Research - 3 p.
    Natuur Ambitie Grote Wateren (NAGW): evaluatie natuur binnen Ruimte voor de Rivier
    In het kader van ruimte voor de rivier zijn in het verleden meerdere maatregelen getroffen waaraan geen concrete ecologische doelen zijn gekoppeld. Om inzicht te krijgen in de ecologische effectiviteit ofwel welke natuurwaarden zijn er aanwezig, zijn in 2018 en 2019 een viertal maatregelen onderzocht. Het gaat hier om 1) het kwelmoeras in de Amerongse Bovenpolder, 2) de meestromende nevengeulen in de Vreugderijkerwaard, 3) twee geïsoleerde strangen in Cortenoever-Stokebrand en 4) ontsteende Kribvakken langs de IJssel nabij Zutphen. Naast vegetatie zijn zoetwatervissen, amfibieën, bevers, otters en vogels onderzocht. De eerste bevindingen zijn samenvattend weergegeven in de bijgaande drie pagina’s tellende factsheet per gebied.

    NAGW factsheet 1: Amerongse Bovenpolder.
    NAGW factsheet 2: Vreugderijkerwaard.
    NAGW factsheet 3: Cortenoever-Stokebrand.

    Fabrice Ottburg
    Impact of hydraulic retention time on community assembly and function of photogranules for wastewater treatment
    Trebuch, L.M. ; Oyserman, B.O. ; Janssen, M. ; Wijffels, R.H. ; Vet, L.E.M. ; Fernandes, T.V. - \ 2020
    Water Research 173 (2020). - ISSN 0043-1354
    Extracellular polymeric substances - Functional network - Metagenomics - Microalgae and cyanobacteria - Microbial ecology - Phototrophic granulation

    Photogranules are dense, spherical agglomerates of cyanobacteria, microalgae and non-phototrophic microorganisms that have considerable advantages in terms of harvesting and nutrient removal rates for light driven wastewater treatment processes. This ecosystem is poorly understood in terms of the microbial community structure and the response of the community to changing abiotic conditions. To get a better understanding, we investigated the effect of hydraulic retention time (HRT) on photogranule formation and community assembly over a period of 148 days. Three laboratory bioreactors were inoculated with field samples from various locations in the Netherlands and operated in sequencing batch mode. The bioreactors were operated at four different HRTs (2.00, 1.00, 0.67, 0.33 days), while retaining the same solid retention time of 7 days. A microbial community with excellent settling characteristics (95–99% separation efficiency) was established within 2–5 weeks. The observed nutrient uptake rates ranged from 24 to 90 mgN L−1 day−1 and from 3.1 to 5.4 mgP L−1 day−1 depending on the applied HRT. The transition from single-cell suspension culture to floccular agglomeration to granular sludge was monitored by microscopy and 16S/18S sequencing. In particular, two important variables for driving aggregation and granulation, and for the structural integrity of photogranules were identified: 1. Extracellular polymeric substances (EPS) with high protein to polysaccharide ratio and 2. specific microorganisms. The key players were found to be the cyanobacteria Limnothrix and Cephalothrix, the colony forming photosynthetic eukaryotes within Chlamydomonadaceae, and the biofilm producing bacteria Zoogloea and Thauera. Knowing the makeup of the microbial community and the operational conditions influencing granulation and bioreactor function is crucial for successful operation of photogranular systems.

    AGINFRA PLUS: Running Crop Simulations on the D4Science Distributed e-Infrastructure
    Knapen, M.J.R. ; Lokers, R.M. ; Candela, L. ; Janssen, S.J.C. - \ 2020
    In: Environmental Software Systems. - Springer (IFIP Advances in Information and Communication Technology ) - ISBN 9783030398149 - p. 81 - 89.
    Virtual Research Environments (VREs) bridge the gap between the compute and storage infrastructure becoming available as the ‘cloud’, and the needs of researchers for tools supporting open science and analytics on ever larger datasets. In the AGINFRA PLUS project such a VRE, based on the D4Science platform, was examined to improve and test its capabilities for running large numbers of crop simulations at field level, based on the WOFOST-WISS model and Dutch input datasets from the AgroDataCube. Using the gCube DataMiner component of the VRE, and based on the Web Processing Service standard, a system has been implemented that can run such workloads successfully on an available cluster, and with good performance, providing summarized results to agronomists for further analysis. The methods used and the resulting implementation are briefly described in this paper. Overall the approach seems viable and opening the door to many follow-up implementation opportunities and further research. Some of them are indicated in more detail in the conclusions.
    Eight grand challenges in socio-environmental systems modeling
    Elsawah, Sondoss ; Filatova, Tatiana ; Jakeman, Anthony J. ; Kettner, Albert J. ; Zellner, Moira L. ; Athanasiadis, Ioannis N. ; Hamilton, Serena H. ; Axtell, Robert L. ; Brown, Daniel G. ; Gilligan, Jonathan M. ; Janssen, Marco A. ; Robinson, Derek T. ; Rozenberg, Julie ; Ullah, Isaac I.T. ; Lade, Steve J. - \ 2020
    Socio-Environmental Systems Modelling 2 (2020). - ISSN 2663-3027
    Modeling is essential to characterize and explore complex societal and environmental issues in systematic and collaborative ways. Socio-environmental systems (SES) modeling integrates knowledge and perspectives into conceptual and computational tools that explicitly recognize how human decisions affect the environment. Depending on the modeling purpose, many SES modelers also realize that involvement of stakeholders and experts is fundamental to support social learning and decision-making processes for achieving improved environmental and social outcomes. The contribution of this paper lies in identifying and formulating grand challenges that need to be overcome to accelerate the development and adaptation of SES modeling. Eight challenges are delineated: bridging epistemologies across disciplines; multi-dimensional uncertainty assessment and management; scales and scaling issues; combining qualitative and quantitative methods and data; furthering the adoption and impacts of SES modeling on policy; capturing structural changes; representing human dimensions in SES; and leveraging new data types and sources. These challenges limit our ability to effectively use SES modeling to provide the knowledge and information essential for supporting decision making. Whereas some of these challenges are not unique to SES modeling and may be pervasive in other scientific fields, they still act as barriers as well as research opportunities for the SES modeling community. For each challenge, we outline basic steps that can be taken to surmount the underpinning barriers. Thus, the paper identifies priority research areas in SES modeling, chiefly related to progressing modeling products, processes and practices.
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