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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Conductive thin film drying kinetics relevant to drum drying
Qiu, J. ; Kloosterboer, Koen ; Guo, Yang ; Boom, R.M. ; Schutyser, M.A.I. - \ 2019
Journal of Food Engineering 242 (2019). - ISSN 0260-8774 - p. 68 - 75.
Direct assessment of the kinetics of drum drying operation has been a difficult task as the mass and temperature profiles are hard to monitor. Still, developing better understanding of conductive drying would help to identify new operating windows for this technology. The drying kinetics was investigated by drying maltodextrin and starch suspensions with a novel custom-built laboratory-scale apparatus, which allows on-line monitoring of mass and temperatures. During drying, three separate periods were identified: the heating, the boiling and the conductive drying (declining rate) periods. The duration of the initial heating period was proportional to the film thickness and was responsible for a relatively small amount of water evaporated due to natural convection. During the boiling period, the drying rate kept constant while bubble formation impeded the heat transfer. Larger bubbles were observed for starch suspensions due to its viscoelastic properties. Thus, large temperature gradients between the heating pan and the film were observed for starch suspensions. During the conductive drying period, the initial amount of dry solids per surface area determines the drying rate as it determines the thickness of the semi-moist layer subjected to conductive drying. Application of a thin film is preferred to avoid boiling, especially at increasing solids content. This situation also better approaches double drum drying processes, where boiling occurs in the pool and conductive drying occurs on the drum.
Network Analyses Can Advance Above-Belowground Ecology
Ramirez, Kelly S. ; Geisen, Stefan ; Morriën, Elly ; Snoek, Basten L. ; Putten, Wim H. van der - \ 2018
Trends in Plant Science 23 (2018)9. - ISSN 1360-1385 - p. 759 - 768.
community ecology - global change - species interactions - terrestrial ecology

An understanding of above-belowground (AG-BG) ecology is important for evaluating how plant interactions with enemies, symbionts, and decomposers affect species diversity and will respond to global changes. However, research questions and experiments often focus on only a limited number of interactions, creating an incomplete picture of how entire communities may be involved in AG-BG community ecology. Therefore, a pressing challenge is to formulate hypotheses of AG-BG interactions when considering communities in their full complexity. Here we discuss how network analyses can be a powerful tool to progress AG-BG research, link across scales from individual to community and ecosystem, visualize community interactions between the two (AG and BG) subsystems, and develop testable hypotheses.

Bioaccumulation and Biotransformation of Triclosan and Galaxolide in the Freshwater Oligochaete Limnodrilus hoffmeisteri in a Water/Sediment Microcosm
Peng, Feng-Jiao ; Ying, Guang Guo ; Pan, Chang Gui ; Selck, Henriette ; Salvito, Daniel ; Brink, Paul J. van den - \ 2018
Environmental Science and Technology 52 (2018)15. - ISSN 0013-936X - p. 8390 - 8398.

Personal care products are widely used in our daily life in considerable quantities and discharged via the down-the-drain route to aquatic environments, resulting in potential risks to aquatic organisms. We investigated bioaccumulation and biotransformation of two widely used personal care products, triclosan (TCS) and galaxolide (HHCB) spiked to sediment, in the oligochaete worm Limnodrilus hoffmeisteri in water/sediment microcosms. After 7 days of sediment exposure to 3.1 μg of TCS or HHCB/g of dry weight sediment, the accumulation of TCS and HHCB in L. hoffmeisteri reached equilibrium, at which point the biota-sediment accumulation factors (BSAFs) were 2.07 and 2.50 for TCS and HHCB, respectively. The presence of L. hoffmeisteri significantly accelerated the dissipation of the levels of TCS and HHCB in the microcosms, with approximately 9.03 and 2.90% of TCS and HHCB, respectively, eliminated from the water/sediment systems after exposure for 14 days in the presence of worms. Two biotransformation products, methyl triclosan and triclosan O-sulfate, were identified for TCS in worm tissue, whereas only methyl triclosan was identified in the sediment. Unlike TCS, no evidence of biotransformation products was found for HHCB in either worm tissue or sediment. These experiments demonstrate that L. hoffmeisteri biotransformed TCS through methylation and sulfation, whereas HHCB biotransformation was undetectable.

Supplement use and dietary sources of folate, vitamin D, and n-3 fatty acids during preconception : The GLIMP2 study
Looman, Moniek ; Berg, Claudia van den; Geelen, Anouk ; Samlal, Rahul A.K. ; Heijligenberg, Rik ; Klein Gunnewiek, Jacqueline M.T. ; Balvers, Michiel G.J. ; Leendertz-Eggen, Caroline L. ; Wijnberger, Lia D.E. ; Feskens, Edith J.M. ; Brouwer-Brolsma, Elske M. - \ 2018
Nutrients 10 (2018)8. - ISSN 2072-6643
Diet - Folate - N-3 fatty acids - Preconception - Supplements - Vitamin D

An adequate nutritional status during the preconception period is important, particularly for folate, vitamin D, and n-3 fatty acids (i.e., EPA+DHA). We aimed to determine supplement intake and the main dietary sources of folate, vitamin D, and EPA+DHA using the data of 66 Dutch women aged 18–40 years who wished to become pregnant. Additionally, associations of these intakes with their blood levels were examined. Dietary intake was assessed with a validated food frequency questionnaire, and supplement use with a structured questionnaire. 25-hydroxyvitamin D levels were determined in serum and folate and phospholipid EPA+DHA levels in plasma. Partial Spearman’s correlations, restricted cubic splines and trend analyses over tertiles of nutrient intakes were performed to examine intake-status associations. A large proportion of women did not meet the Dutch recommended intakes of folate (50%), vitamin D (67%), and EPA+DHA (52%). Vegetables were the main contributor to dietary folate intake (25%), oils and fats to dietary vitamin D intake (39%), and fish to dietary EPA+DHA intake (69%). Fourteen percent of the women had an inadequate folate status and 23% an inadequate vitamin D status. Supplemental folate intake, supplemental and dietary vitamin D intake and dietary EPA+DHA intake were significantly associated with their blood levels. In conclusion, even in our highly educated population, a large proportion did not achieve recommended folate, vitamin D and n-3 fatty acid intakes. Promotion of folate and vitamin D supplement use and fish consumption is needed to improve intakes and blood levels of these nutrients in women who wish to become pregnant.

Environmental impacts of experimental production of lactic acid for bioplastics from Ulva spp
Helmes, Roel J.K. ; López-Contreras, Ana M. ; Benoit, Maud ; Abreu, Helena ; Maguire, Julie ; Moejes, Fiona ; Burg, Sander W.K. van den - \ 2018
Sustainability 10 (2018)7. - ISSN 2071-1050
Bioplastics - Lactic acid - Life Cycle Assessment - Seaweed - Ulva spp

An exploratory Life Cycle Assessment (LCA) was carried out to provide insight into the environmental impacts of using the green seaweed Ulva spp. as a feedstock, for production of bioplastic. The study focused on the production of lactic acid as a precursor of polylactic acid. The study was on the production process: (1) The cultivation of Ulva spp., in an Integrated Multitrophic Aquaculture system; (2) the processing of the biomass for solubilization of sugars; (3) the fermentation of the sugars to lactic acid; (4) the isolation of lactic acid from fermentation broth. The study identified environmental hotspots and compared an experimental seaweed production chain with conventional feedstocks. The main hotspot is derived from electricity consumption during seaweed cultivation. The impact of electricity consumption can be lowered by reducing energy use and sourcing renewable energy, and by improving the material efficiency in the product chain. To improve understanding of the process of production's environmental impacts, future studies should broaden the system boundaries and scope of sustainability issues included in the environmental assessment.

Fate and effects of sediment-associated triclosan in subtropical freshwater microcosms
Peng, Feng-Jiao ; Diepens, Noël J. ; Pan, Chang-Gui ; Bracewell, Sally A. ; Ying, Guang-Guo ; Salvito, Daniel ; Selck, Henriette ; Brink, Paul J. Van den - \ 2018
Aquatic Toxicology 202 (2018). - ISSN 0166-445X - p. 117 - 125.
Benthic macroinvertebrates - Bioaccumulation - Dissipation - Partitioning - Toxicity

Triclosan (TCS) is an antibacterial agent that is commonly used in personal care products. Because of its sediment-binding properties, TCS exposure presents a potential threat to sediment-dwelling aquatic organisms. Currently our knowledge of the fate and effects of sediment-associated TCS in aquatic systems is limited. To understand the impact of sediment-associated TCS, we used microcosms to assess effects of TCS exposure on a diverse range of organisms selected to mimic a subtropical community, with an exposure period of 28 days. We included the oligochaete freshwater worm Limnodrilus hoffmeisteri to evaluate the interaction between sediment-associated TCS and sediment-dwelling organisms, including potential loss of TCS from the sediment due to biological activity and bioaccumulation. Benthic macroinvertebrate presence significantly increased the TCS levels from 0.013 ± 0.007 μg/L to 0.613 ± 0.030 μg/L in the overlying water through biological activity, posing a potential additional risk to pelagic species, but it did not result in a significant reduction of the sediment concentration. Furthermore, worms accumulated TCS with estimated Biota-Sediment-Accumulation-Factors (BSAFs) ranging between 0.38–3.55. Other than for algae, TCS at environmental concentrations did not affect the survival of the introduced organisms, including the L. hoffmeisteri. Our results demonstrate that, although TCS at currently detected maximum concentration may not have observable toxic effects on the benthic macroinvertebrates in the short term, it can lead to bioaccumulation in worms.

Circumpolar Arctic Vegetation Classification
Walker, Donald A. ; Daniëls, Fred J.A. ; Matveyeva, Nadezhda V. ; Šibík, Jozef ; Walker, Marilyn D. ; Breen, Amy L. ; Druckenmiller, Lisa A. ; Raynolds, Martha K. ; Bültmann, Helga ; Hennekens, Stephan ; Buchhorn, Marcel ; Epstein, Howard E. ; Ermokhina, Ksenia ; Fosaa, Anna M. ; Heidmarsson, Starri ; Heim, Birgit ; Jónsdóttir, Ingibjörg S. ; Koroleva, Natalia ; Lévesque, Esther ; MacKenzie, William H. ; Henry, Greg H.R. ; Nilsen, Lennart ; Peet, Robert ; Razzhivin, Volodya ; Talbot, Stephen S. ; Telyatnikov, Mikhail ; Thannheiser, Dietbert ; Webber, Patrick J. ; Wirth, Lisa M. - \ 2018
Phytocoenologia 48 (2018)2. - ISSN 0340-269X - p. 181 - 201.
Alaska - Bioclimate gradient - Braun-Blanquet approach - Habitat type - Plant growth form - Plot database - Syntaxon - Tundra - Vegetation mapping

Aims: An Arctic Vegetation Classification (AVC) is needed to address issues related to rapid Arctic-wide changes to climate, land-use, and biodiversity. Location: The 7.1 million km2 Arctic tundra biome. Approach and conclusions: The purpose, scope and conceptual framework for an Arctic Vegetation Archive (AVA) and Classification (AVC) were developed during numerous workshops starting in 1992. The AVA and AVC are modeled after the European vegetation archive (EVA) and classification (EVC). The AVA will use Turboveg for data management. The AVC will use a Braun-Blanquet (Br.-Bl.) classification approach. There are approximately 31,000 Arctic plots that could be included in the AVA. An Alaska AVA (AVA-AK, 24 datasets, 3026 plots) is a prototype for archives in other parts of the Arctic. The plan is to eventually merge data from other regions of the Arctic into a single Turboveg v3 database. We present the pros and cons of using the Br.-Bl. classification approach compared to the EcoVeg (US) and Biogeoclimatic Ecological Classification (Canada) approaches. The main advantages are that the Br.-Bl. approach already has been widely used in all regions of the Arctic, and many described, well-accepted vegetation classes have a pan-Arctic distribution. A crosswalk comparison of Dryas octopetala communities described according to the EcoVeg and the Braun-Blanquet approaches indicates that the non-parallel hierarchies of the two approaches make crosswalks difficult above the plantcommunity level. A preliminary Arctic prodromus contains a list of typical Arctic habitat types with associated described syntaxa from Europe, Greenland, western North America, and Alaska. Numerical clustering methods are used to provide an overview of the variability of habitat types across the range of datasets and to determine their relationship to previously described Braun-Blanquet syntaxa. We emphasize the need for continued maintenance of the Pan-Arctic Species List, and additional plot data to fully sample the variability across bioclimatic subzones, phytogeographic regions, and habitats in the Arctic. This will require standardized methods of plot-data collection, inclusion of physiogonomic information in the numeric analysis approaches to create formal definitions for vegetation units, and new methods of data sharing between the AVA and national vegetation- plot databases.

Removal, biotransformation and toxicity variations of climbazole by freshwater algae Scenedesmus obliquus
Pan, Chang Gui ; Peng, Feng Jiao ; Ying, Guang Guo - \ 2018
Environmental Pollution 240 (2018). - ISSN 0269-7491 - p. 534 - 540.
CBZ-OH - Climbazole - Green algae - Growth inhibition - Kinetics

Climbazole (CBZ) is an antibacterial and antifungal agent widely used in personal care products. In this study, we investigated the interactions between climbazole (CBZ) and freshwater microalgae Scenedesmus obliquus (S. obliquus). Dose-effect relationships between CBZ concentrations and growth inhibitions or chlorophyll a content were observed. After 12 days of incubation, the algae density and chlorophyll a content in 2 mg/L treatment group was 56.6% and 15.8% of those in the control group, respectively. Biotransformation was the predominant way to remove CBZ in the culture solution, whereas the contribution of bioaccumulation and bioadsorption were negligible. More than 88% of CBZ was removed by S. obliquus across all treatments after 12 days of incubation, and the biotransformation of CBZ followed the first order kinetic model with half-lives of approximately 4.5 days at different treatments. CBZ-alcohol (CBZ-OH) was the only biotransformation product identified in algal solution. Moreover, the toxicity of biotransformation products was much lower than its corresponding precursor compound (CBZ). The results of this study revealed that S. obliquus might have a great impact on the environmental fates of CBZ and could be further applied to remove organic pollutants in aquatic environment. S. obliquus can effectively remove CBZ through biotransformation process in algal solution with CBZ-OH as the identified products.

Transcriptome analysis for the scale-down of a CHO cell fed-batch process
Alsayyari, Abdulaziz A. ; Pan, Xiao ; Dalm, Ciska ; Veen, Jochem W. van der; Vriezen, Nienke ; Hageman, Jos A. ; Wijffels, René H. ; Martens, Dirk E. - \ 2018
Journal of Biotechnology 279 (2018). - ISSN 0168-1656 - p. 61 - 72.
Ambr - CHO cell culture - Fed-batch - mAb production - Scale-down - Transcriptome analysis

Transcriptome and metabolism analysis were performed to evaluate the scale-down of a CHO cell fed-batch process from a 10 L bioreactor to an ambr 15® (ambr) system. Two different agitation scale-down principles were applied, resulting in two different agitation rates in the ambr system: 1300 RPM based on the agitator tip speed, and 800 rpm based on the volumetric power input (P/V). Culture performance including cell growth, product titer, glycosylation, and specific consumption/production rates of metabolites was the same for both agitation rates in the ambr and was comparable to that of the 10 L system. The initial variation in gene expression between the inocula for the ambr and 10 L system was no longer present after three days of culture, indicating comparable culture conditions in both systems. Based on principal component analysis, changes in gene expression over time were similar between both scales with less than 6% variation. 2455 genes were uniquely regulated in the ambr system compared to 1604 genes in the 10 L system. Functional analysis of these genes did not reveal their relations with scale or cellular function. This study further strengthens that the ambr system gives representative culture performance for the 10 L bench-scale bioreactor.

Scale-down of CHO cell fed-batch cultures
Pan, Xiao - \ 2018
University. Promotor(en): Rene Wijffels, co-promotor(en): Dirk Martens. - Wageningen : Wageningen University - ISBN 9789463438438 - 157
A possible molecular basis for photoprotection in the minor antenna proteins of plants
Fox, Kieran F. ; Ünlü, Caner ; Balevičius, Vytautas ; Ramdour, Baboo Narottamsing ; Kern, Carina ; Pan, Xiaowei ; Li, Mei ; Amerongen, Herbert van; Duffy, Christopher D.P. - \ 2018
Biochimica et Biophysica Acta. B, Bioenergetics 1859 (2018)7. - ISSN 0005-2728 - p. 471 - 481.
Carotenoids - Light-harvesting - Minor antenna - Non-photochemical quenching - Photoprotection - Photosystem II

The bioenergetics of light-harvesting by photosynthetic antenna proteins in higher plants is well understood. However, investigation into the regulatory non-photochemical quenching (NPQ) mechanism, which dissipates excess energy in high light, has led to several conflicting models. It is generally accepted that the major photosystem II antenna protein, LHCII, is the site of NPQ, although the minor antenna complexes (CP24/26/29) are also proposed as alternative/additional NPQ sites. LHCII crystals were shown to exhibit the short excitation lifetime and several spectral signatures of the quenched state. Subsequent structure-based models showed that this quenching could be explained by slow energy trapping by the carotenoids, in line with one of the proposed models. Using Fluorescence Lifetime Imaging Microscopy (FLIM) we show that the crystal structure of CP29 corresponds to a strongly quenched conformation. Using a structure-based theoretical model we show that this quenching may be explained by the same slow, carotenoid-mediated quenching mechanism present in LHCII crystals.

Computational genomics of specialized metabolism : From natural product discovery to microbiome ecology
Medema, Marnix H. - \ 2018
mSystems 3 (2018)2. - ISSN 2379-5077
Bioinformatics - Biosynthetic gene cluster - Microbiome - Natural products - Specialized metabolism
Microbial and plant specialized metabolites, also known as natural products, are key mediators of microbe-microbe and host-microbe interactions and constitute a rich resource for drug development. In the past decade, genome mining has emerged as a prominent strategy for natural product discovery. Initially, such mining was performed on the basis of individual microbial genome sequences. Now, these efforts are being scaled up to fully genome-sequenced strain collections, pan-genomes of bacterial genera, and large sets of metagenome-assembled genomes from microbial communities. The Medema research group aims to play a leading role in these developments by developing and applying computational approaches to identify, classify, and prioritize specialized metabolite biosynthetic gene clusters and pathways and to connect them to specific molecules and microbiome-associated phenotypes. Moreover, we are extending the scope of genome mining from microbes to plants, which will allow more comprehensive interpretation of the chemical language between hosts and microbes in a microbiome setting.
Implications of changes in land cover and landscape structure for the biocontrol potential of stemborers in Ethiopia
Kebede, Yodit ; Bianchi, Felix ; Baudron, Frédéric ; Abraham, Kristin ; Valença, Anne de; Tittonell, Pablo - \ 2018
Biological Control 122 (2018). - ISSN 1049-9644 - p. 1 - 10.
Agroecosystem - Busseola fusca (Fuller) - Land use - Landscape ecology - Maize - Natural enemies
The land cover and structure of agricultural landscapes may influence the abundance and diversity of natural enemies of crop pests. However, these landscapes are continuously evolving due to changing land uses and agricultural practices. Here we assess changes in land use and landscape structure in a landscape in the Rift Valley region of Ethiopia, and explore the impact these changes are likely to have on the capacity of the landscape to support communities of natural enemies of maize stemborers Busseola fusca (Fuller). Land use and landscape structure were assessed in three periods over the last 30 years using focus group discussions with farmers and land use analysis through remote sensing. Natural enemies were sampled in maize fields adjacent to simple hedgerows, complex hedgerows, enset fields and khat fields at 1, 10 and 30 m using pitfalls and yellow pan traps in 2014 and 2015. The landscape analysis indicated that landscapes in the study area changed from maize dominated to more diverse small-scale and fragmented agroecosystems with a higher proportion of perennial crops. Maize fields adjacent to enset and complex hedgerows hosted significantly more predators (15.1 ± 9.8 and 22.3 ± 5.1 per trap at 1 m from the border, respectively) than maize fields adjacent to khat and simple hedgerows (7.2 ± 1.1 and 7.3 ± 1.7 per trap at 1 m from the border), and the effects of border type decreased with distance from the border. The abundance of parasitoids and parasitic flies were not influenced by border type. Our findings suggest that the changes in land use and landscape structure may have influenced the capacity of the landscape to support populations of natural enemies of stemborers in different ways. On the one hand smaller field sizes have resulted in more field borders that may support relatively high predator densities; on the other hand, the area of khat increased and the area of enset decreased, which may have a negative effect on predator densities. The overall outcome will depend on the interplay of these opposing effects.
A pan-European model of landscape potential to support natural pest control services
Rega, Carlo ; Bartual, Agustín M. ; Bocci, Gionata ; Sutter, Louis ; Albrecht, Matthias ; Moonen, Anna Camilla ; Jeanneret, Philippe ; Werf, Wopke van der; Pfister, Sonja C. ; Holland, John M. ; Paracchini, Maria Luisa - \ 2018
Ecological Indicators 90 (2018). - ISSN 1470-160X - p. 653 - 664.
Biological control - Green infrastructure - Landscape complexity - Landscape design - Natural pest control - Semi-natural habitats
Pest control by natural enemies (natural pest control) is an important regulating ecosystem service with significant implications for the sustainability of agro-ecosystems. The presence of semi-natural habitats and landscape heterogeneity are key determinants of the delivery of this service. However, to date, synthetic and consistent indicators at large scales are lacking. We developed a pan-European, spatially-explicit model to map and assess the landscape potential to sustain natural pest control. The model considers landscape composition in terms of semi-natural habitats types, abundance, spatial configuration and distance from the focal field. It combines recent high-resolution geospatial layers with empirical results from extensive field surveys measuring the specific contribution of different semi-natural habitats to support insects flying enemies providing natural pest control. The resulting maps facilitate a comparison of the relative biological control potential of different areas and show that currently a large proportion of high-productive agricultural areas in Europe has low potential. The obtained indicator can inform the formulation of policies and planning strategies aimed at increasing biodiversity and ecosystem services and can be used to assess trade-offs between different services. Potential fields of application include the Common Agricultural Policy and the EU Biodiversity Strategy, in particular the implementation of Green Infrastructure.
Species-specific, pan-European diameter increment models based on data of 2.3 million trees
Schelhaas, M. ; Hengeveld, G.M. ; Heidema, A.H. ; Thürig, Esther ; Rohner, Brigitte ; Vacchiano, G. ; Vayreda, Jordi ; Redmond, John ; Socha, J. ; Fridman, Jonas ; Tomter, Stein ; Polley, Heino ; Barreiro, Susana ; Nabuurs, G.J. - \ 2018
Forest Ecosystems 5 (2018). - ISSN 2095-6355 - 19 p.
Background: Over the last decades, many forest simulators have been developed for the forests of individual European countries. The underlying growth models are usually based on national datasets of varying size, obtained from National Forest Inventories or from long-term research plots. Many of these models include country- and location-specific predictors, such as site quality indices that may aggregate climate, soil properties and topography effects. Consequently, it is not sensible to compare such models among countries, and it is often impossible to apply models outside the region or country they were developed for. However, there is a clear need for more generically applicable but still locally accurate and climate sensitive simulators at the European scale, which requires the development of models that are applicable across the European continent. The purpose of this study is to develop tree diameter increment models that are applicable at the European scale, but still locally accurate. We compiled and used a dataset of diameter increment observations of over 2.3 million trees from 10 National Forest Inventories in Europe and a set of 99 potential explanatory variables covering forest structure, weather, climate, soil
and nutrient deposition. Results: Diameter increment models are presented for 20 species/species groups. Selection of explanatory variables was done using a combination of forward and backward selection methods. The explained variance ranged from 10% to 53% depending on the species. Variables related to forest structure (basal area of the stand and relative size of the tree) contributed most to the explained variance, but environmental variables were important to account for spatial patterns. The type of environmental variables included differed greatly among species. Conclusions: The presented diameter increment models are the first of their kind that are applicable at the European scale. This is an important step towards the development of a new generation of forest development simulators that can be applied at the European scale, but that are sensitive to variations in growing conditions and applicable to a wider range of management systems than before. This allows European scale but detailed analyses concerning topics like CO2 sequestration, wood mobilisation, long term impact of management, etc.
Ambidexterity and mobile hubs as the interfaces for orchestrating multi-level innovation networks and fostering capabilities in innovation processes: evidence from agricultural netchains in Sub-Saharan Africa
Pérez Perdomo, Silvia Andrea - \ 2018
University. Promotor(en): Onno Omta; Jacques Trienekens. - Wageningen : Wageningen University - ISBN 9789463436823 - 186

Tackling complex challenges in innovation processes requires the collaborative efforts of innovation networks at various levels. These innovation networks need to be governed appropriately to manage contradictory but also complementary dynamics for innovation.

Exploration and exploitation are concepts that describe different types of dynamics in innovation processes that require management. In this thesis I present ambidexterity as the higher order managerial capability to orchestrate innovation networks while exploring but also exploiting opportunities to innovate, which entails multiple network capabilities.

I analysed stakeholder testimonies and household level panel data from case studies in Uganda, the Democratic Republic of the Congo and Rwanda to assess the performance of innovation networks that aim to tackle complex challenges of family farms in developing countries. I tested the effectiveness of three network governance mechanisms (first order, second order and meta-governance) and their influence on network capabilities.

An ambidextrous management in multi-stakeholder innovation platforms fosters multiple network capabilities and the emergence of mobile hubs to manage various interfaces of innovation networks. However, in contrast to the management of organisations, I found that the management of innovation networks via network governance mechanisms that focus mainly on managing structural challenges, is not the most effective managerial strategy in innovation processes. Managing exploration and exploitation effectively might need a more ambidextrous management of structural, contextual and temporal challenges in interplay, more ‘govern-ability’ and sufficient resources. I recommend further research on the context as a mediating factor between network governance and network-related capabilities. These findings are relevant for managing effectively multi-stakeholder processes for tackling collectively different types of challenges in different contexts.

Influence of carbon anode properties on performance and microbiome of Microbial Electrolysis Cells operated on urine
Barbosa, Sónia G. ; Peixoto, Luciana ; Soares, Olívia S.G.P. ; Pereira, Manuel Fernando R. ; Heijne, Annemiek Ter ; Kuntke, Philipp ; Alves, Maria Madalena ; Pereira, Maria Alcina - \ 2018
Electrochimica Acta 267 (2018). - ISSN 0013-4686 - p. 122 - 132.
Cellulose-based carbon - Microbial community - Microbial electrolysis cell - Phenolic-based carbon - Polyacrilonitrile-based carbon
Anode performance of Microbial Electrolysis Cells (MECs) fed with urine using different anodes, Keynol (phenolic-based), C-Tex (cellulose-based) and PAN (polyacrylonitrile-based) was compared under cell potential control (1st assay) and anode potential control (2nd assay). In both assays, C-Tex MEC outperformed MECs using Keynol and PAN. C-Tex MEC under anode potential control (−0.300 V vs. Ag/AgCl) generated the highest current density (904 mA m−2), which was almost 3-fold higher than the Keynol MEC and 8-fold higher than the PAN MEC. Analysis of anodes textural, chemical and electrochemical characteristics suggest that the higher external surface area of C-Tex enabled higher current density generation compared to Keynol and PAN. Anodes properties did not influence significantly the microbial diversity of the developed biofilm. Nonetheless, C-Tex had higher relative abundance of bacteria belonging to Lactobacillales and Enterobacteriales suggesting its correlation with the higher current generation.
Climate Impacts in Europe Under +1.5°C Global Warming
Jacob, Daniela ; Kotova, Lola ; Teichmann, Claas ; Sobolowski, Stefan P. ; Vautard, Robert ; Donnelly, Chantal ; Koutroulis, Aristeidis G. ; Grillakis, Manolis G. ; Tsanis, Ioannis K. ; Damm, Andrea ; Sakalli, Abdulla ; Vliet, Michelle T.H. van - \ 2018
Earth's Future 6 (2018)2. - ISSN 2328-4277 - p. 264 - 285.
+1.5oC and +2oC global warming - Climate Change - Climate Change Impacts - Europe - IMPACT2C project
The Paris Agreement of the United Nations Framework Convention on Climate Change aims not only at avoiding +2°C warming (and even limit the temperature increase further to +1.5°C), but also sets long-term goals to guide mitigation. Therefore, the best available science is required to inform policymakers on the importance of and the adaptation needs in a +1.5°C warmer world. Seven research institutes from Europe and Turkey integrated their competencies to provide a cross-sectoral assessment of the potential impacts at a pan-European scale. The initial findings of this initiative are presented and key messages communicated. The approach is to select periods based on global warming thresholds rather than the more typical approach of selecting time periods (e.g., end of century). The results indicate that the world is likely to pass the +1.5°C threshold in the coming decades. Cross-sectoral dimensions are taken into account to show the impacts of global warming that occur in parallel in more than one sector. Also, impacts differ across sectors and regions. Alongside the negative impacts for certain sectors and regions, some positive impacts are projected. Summer tourism in parts of Western Europe may be favored by climate change; electricity demand decreases outweigh increases over most of Europe and catchment yields in hydropower regions will increase. However, such positive findings should be interpreted carefully as we do not take into account exogenous factors that can and will influence Europe such as migration patterns, food production, and economic and political instability.
Field methods for sampling tree height for tropical forest biomass estimation
Sullivan, Martin J.P. ; Lewis, Simon L. ; Hubau, Wannes ; Qie, Lan ; Baker, Timothy R. ; Banin, Lindsay F. ; Chave, Jerôme ; Cuni-Sanchez, Aida ; Feldpausch, Ted R. ; Lopez-Gonzalez, Gabriela ; Arets, Eric ; Ashton, Peter ; Bastin, Jean François ; Berry, Nicholas J. ; Bogaert, Jan ; Boot, Rene ; Brearley, Francis Q. ; Brienen, Roel ; Burslem, David F.R.P. ; Canniere, Charles de; Chudomelová, Markéta ; Dančák, Martin ; Ewango, Corneille ; Hédl, Radim ; Lloyd, Jon ; Makana, Jean Remy ; Malhi, Yadvinder ; Marimon, Beatriz S. ; Junior, Ben Hur Marimon ; Metali, Faizah ; Moore, Sam ; Nagy, Laszlo ; Vargas, Percy Nuñez ; Pendry, Colin A. ; Ramírez-Angulo, Hirma ; Reitsma, Jan ; Rutishauser, Ervan ; Salim, Kamariah Abu ; Sonké, Bonaventure ; Sukri, Rahayu S. ; Sunderland, Terry ; Svátek, Martin ; Umunay, Peter M. ; Martinez, Rodolfo Vasquez ; Vernimmen, Ronald R.E. ; Torre, Emilio Vilanova ; Vleminckx, Jason ; Vos, Vincent ; Phillips, Oliver L. - \ 2018
Methods in Ecology and Evolution 9 (2018)5. - ISSN 2041-210X - p. 1179 - 1189.
Above-ground biomass estimation - Allometry - Carbon stocks - Forest inventory - Forest structure - Sample size
Quantifying the relationship between tree diameter and height is a key component of efforts to estimate biomass and carbon stocks in tropical forests. Although substantial site-to-site variation in height-diameter allometries has been documented, the time consuming nature of measuring all tree heights in an inventory plot means that most studies do not include height, or else use generic pan-tropical or regional allometric equations to estimate height. Using a pan-tropical dataset of 73 plots where at least 150 trees had in-field ground-based height measurements, we examined how the number of trees sampled affects the performance of locally derived height-diameter allometries, and evaluated the performance of different methods for sampling trees for height measurement. Using cross-validation, we found that allometries constructed with just 20 locally measured values could often predict tree height with lower error than regional or climate-based allometries (mean reduction in prediction error = 0.46 m). The predictive performance of locally derived allometries improved with sample size, but with diminishing returns in performance gains when more than 40 trees were sampled. Estimates of stand-level biomass produced using local allometries to estimate tree height show no over- or under-estimation bias when compared with biomass estimates using field measured heights. We evaluated five strategies to sample trees for height measurement, and found that sampling strategies that included measuring the heights of the ten largest diameter trees in a plot outperformed (in terms of resulting in local height-diameter models with low height prediction error) entirely random or diameter size-class stratified approaches. Our results indicate that even limited sampling of heights can be used to refine height-diameter allometries. We recommend aiming for a conservative threshold of sampling 50 trees per location for height measurement, and including the ten trees with the largest diameter in this sample.
Updated procedure for the safety evaluation of natural flavor complexes used as ingredients in food
Cohen, Samuel M. ; Eisenbrand, Gerhard ; Fukushima, Shoji ; Gooderham, Nigel J. ; Guengerich, F.P. ; Hecht, Stephen S. ; Rietjens, Ivonne M.C.M. ; Davidsen, Jeanne M. ; Harman, Christie L. ; Taylor, Sean V. - \ 2018
Food and Chemical Toxicology 113 (2018). - ISSN 0278-6915 - p. 171 - 178.
Botanicals - Complex mixtures - Flavoring - Food - GRAS - Threshold of toxicological concern - Toxicology

An effective and thorough approach for the safety evaluation of natural flavor complexes (NFCs) was published in 2005 by the Expert Panel of the Flavor and Extract Manufacturers Association (FEMA). An updated procedure is provided here, which maintains the essential concepts of the use of the congeneric group approach and the reliance on the threshold of toxicological concern (TTC) concept. The updated procedure emphasizes more rigorous considerations of unidentified constituents and the genotoxic potential of constituents. The update of the previously established procedure is the first step in a multi-year project to conduct safety re-evaluations for more than 250 NFCs that have uses that are currently considered Generally Recognized as Safe (GRAS) by the FEMA Expert Panel. In addition, this procedure can be more generally employed in the safety evaluation of NFCs.

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