A compositional process control model and its application to biochemical processes

A compositional generic process control model is presented which has been applied to control enzymatic biochemical processes. The model has been designed at a conceptual and formal level using the compositional development method DESIRE, and includes processes for analysis, planning and simulation. It integrates qualitative and quantitative techniques. Its application to enzymatic chemical processes is described.     

Developments in soil phosphorus status in a recently reclaimed polder in the Netherlands

Compliance with current phosphorus (P) fertilization recommendations would ultimately result in a soil P status of agricultural land in the agronomical optimal range. In practice though there are large variations in soil P status among farms and fields. Our study aimed at increasing the understanding of the cause-effect relationships for these spatial variations in soil P test values. The Northeast Polder in The Netherlands was chosen as study area, because of its characteristics. It was reclaimed from the sea in 1942, has one major soil type (calcareous loam), well-educated farmers, one dominant land use (arable farming) and little pressure to use animal manure. We tested the hypothesis that in this polder mean P status has developed towards the optimal range with a small standard deviation. We analysed available soil P analyses records (>30,000) from the period ~1950?C2004, and conducted a questionnaire about fertilization practices among farmers. The soil P(w) values increased steadily and significantly from the agronomical range ??low?? to ??ample sufficient?? from 1971 to 2004. Variation within and between farms also increased. About 45?% of the farmers appear to aim at a soil P status above the agronomical optimal range, and >70?% of the farmers indicated that they are uncertain whether the obtained increase in soil P(w) status is actually plant available P. In conclusion, our hypothesis was rejected: for farmers in our study area, risk avoidance seems the decisive factor for pursuing a soil P status above the agronomical optimal range. If even well-educated farmers question the official fertilizer recommendations and aim at higher levels of soil P fertility, also other farmers worldwide may continue to aim such supra-optimal soil P status. This is undesirable given the diminishing P resources. Possible solutions could be to define more refined P fertilization recommendations and better and more intensified communication of those recommendations to farmers and their advisers.     

Catalytic One‐Pot Oxetane to Carbamate Conversions: Formal Synthesis of Drug Relevant Molecules

Oxetanes are versatile building blocks in drug‐related synthesis to induce property‐modulating effects. Whereas related oxiranes are widely used in coupling chemistry with carbon dioxide (CO₂) to afford value‐added commodity chemicals, oxetane/CO₂ couplings remain extremely limited despite the recent advances in the synthesis of these four‐membered heterocycles. Here we report an effective one‐pot three‐component reaction (3CR) strategy for the coupling of (substituted) oxetanes, amines and CO₂ to afford a variety of functionalized carbamates with excellent chemoselectivity and good yields. The process is mediated by an aluminium‐based catalyst under relatively mild conditions and the developed catalytic methodology can be applied to the formal synthesis of two pharmaceutically relevant carbamates with the 3CR being a key step.