| 1. |
- Chávez, Georgina, et al.
(author)
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Baeyer-Villiger Oxidation of Cyclohexanone in Aqueous Medium with In Situ Generation of Peracid Catalyzed by Perhydrolase CLEA
- 2014
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In: Topics in Catalysis. - : Springer Science and Business Media LLC. - 1572-9028 .- 1022-5528. ; 57:5, s. 349-355
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Journal article (peer-reviewed)abstract
- A perhydrolase, immobilized as a cross linked enzyme aggregate (CLEA), was employed to catalyze the in situ formation of peracetic acid (PAA) from ethylene glycol diacetate (EGDA) and hydrogen peroxide. The produced PAA was used for the Baeyer-Villiger oxidation of cyclohexanone, which afforded caprolactone in 63 % yield. The effect of type and amount of acyl donor, solvent, pH, temperature and ratio of cyclohexanone to hydrogen peroxide on the production of caprolactone was studied. The highest caprolactone yield was obtained with 100 mM EGDA as the acyl donor at pH 6 and room temperature using a ratio of cyclohexanone to hydrogen peroxide ratio of 1:4. Interestingly, the perhydrolase CLEA exhibited the highest activity in aqueous medium in contrast to the well studied lipase B from Candida antarctica. The perhydrolase CLEA proved to be a very efficient catalyst; the K (m) and V-max values were 118 mM and 56.3 mu mol min(-1), respectively.
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| 2. |
- De Laender, Frederik, et al.
(author)
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The contribution of intra- and interspecific tolerance variability to biodiversity changes along toxicity gradients
- 2014
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In: Ecology Letters. - : Wiley-Blackwell. - 1461-023X .- 1461-0248. ; 17:1, s. 72-81
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Journal article (peer-reviewed)abstract
- The worldwide distribution of toxicants is an important yet understudied driver of biodiversity, and the mechanisms relating toxicity to diversity have not been adequately explored. Here, we present a community model integrating demography, dispersal and toxicant-induced effects on reproduction driven by intraspecific and interspecific variability in toxicity tolerance. We compare model predictions to 458 species abundance distributions (SADs) observed along concentration gradients of toxicants to show that the best predictions occur when intraspecific variability is five and ten times higher than interspecific variability. At high concentrations, lower settings of intraspecific variability resulted in predictions of community extinction that were not supported by the observed SADs. Subtle but significant species losses at low concentrations were predicted only when intraspecific variability dominated over interspecific variability. Our results propose intraspecific variability as a key driver for biodiversity sustenance in ecosystems challenged by environmental change.
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| 3. |
- Mooij, Wolf M., et al.
(author)
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Serving many at once : How a database approach can create unity in dynamical ecosystem modelling
- 2014
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In: Environmental Modelling & Software. - : Elsevier BV. - 1364-8152 .- 1873-6726. ; 61, s. 266-273
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Journal article (peer-reviewed)abstract
- Simulation modelling in ecology is a field that is becoming increasingly compartmentalized. Here we propose a Database Approach To Modelling (DATM) to create unity in dynamical ecosystem modelling with differential equations. In this approach the storage of ecological knowledge is independent of the language and platform in which the model will be run. To create an instance of the model, the information in the database is translated and augmented with the language and platform specifics. This process is automated so that a new instance can be created each time the database is updated. We describe the approach using the simple Lotka-Volterra model and the complex ecosystem model for shallow lakes PCLake, which we automatically implement in the frameworks OSIRIS, GRIND for MATLAB, ACSL, R, DUFLOW and DELWAQ. A clear advantage of working in a database is the overview it provides. The simplicity of the approach only adds to its elegance.
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| 4. |
- van Gerven, Luuk P. A., et al.
(author)
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Advantages of concurrent use of multiple software frameworks in water quality modelling using a database approach
- 2015
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In: Fundamental and Applied Limnology. - : Schweizerbart. - 1863-9135. ; 186:1-2, s. 5-20
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Journal article (peer-reviewed)abstract
- Water quality modelling deals with multidisciplinary questions ranging from fundamental to applied. Addressing this broad range of questions requires multiple analysis techniques and therefore multiple frameworks. Through the recently developed database approach to modelling (DATM), it has become possible to run a model in multiple software frameworks without much overhead. Here we apply DATM to the ecosystem model for ditches PCDitch and its twin model for shallow lakes PCLake. Using DATM, we run these models in six frameworks (ACSL, DELWAQ, DUFLOW, GRIND for MATLAB, OSIRIS and R), and report on the possible model analyses with tools provided by each framework. We conclude that the dynamic link between frameworks and models resulting from DATM has the following main advantages: it allows one to use the framework one is familiar with for most model analyses and eases switching between frameworks for complementary model analyses, including the switch between a 0-D and 1-D to 3-D setting. Moreover, the strength of each framework - including runtime performance - can now be easily exploited. We envision that a community-based further development of the concept can contribute to the future development of water quality modelling, not only by addressing multidisciplinary questions but also by facilitating the exchange of models and process formulations within the community of water quality modellers.
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