| 1. |
- Cornelissen, Johannes H C, et al.
(författare)
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Global negative vegetation feedback to climate warming responses of leaf litter decomposition rates in cold biomes
- 2007
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Ingår i: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 10:7, s. 619-627
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Tidskriftsartikel (refereegranskat)abstract
- Whether climate change will turn cold biomes from large long-term carbon sinks into sources is hotly debated because of the great potential for ecosystem-mediated feedbacks to global climate. Critical are the direction, magnitude and generality of climate responses of plant litter decomposition. Here, we present the first quantitative analysis of the major climate-change-related drivers of litter decomposition rates in cold northern biomes worldwide.Leaf litters collected from the predominant species in 33 global change manipulation experiments in circum-arctic-alpine ecosystems were incubated simultaneously in two contrasting arctic life zones. We demonstrate that longer-term, large-scale changes to leaf litter decomposition will be driven primarily by both direct warming effects and concomitant shifts in plant growth form composition, with a much smaller role for changes in litter quality within species. Specifically, the ongoing warming-induced expansion of shrubs with recalcitrant leaf litter across cold biomes would constitute a negative feedback to global warming. Depending on the strength of other (previously reported) positive feedbacks of shrub expansion on soil carbon turnover, this may partly counteract direct warming enhancement of litter decomposition.
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| 2. |
- Karlsson, Björn C. G., et al.
(författare)
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Structure and Dynamics of Monomer-Template Complexation: An Explanation for Molecularly Imprinted Polymer Recognition Site Heterogeneity
- 2009
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 131:37, s. 13297-13304
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Tidskriftsartikel (refereegranskat)abstract
- We here present the first simulation of a complete molecularly imprinted polymer prepolymerization system. Molecular dynamics studies were performed for a system comprising a total of 1199 discrete molecules, replicating the components and concentrations employed in the corresponding polymer synthesis. The observed interactions correlate well with results obtained from (1)H NMR spectroscopic studies. Comparison with simulations performed in the absence of cross-linking agent (ethylene dimethacrylate) demonstrated its significance in the formation of ligand recognition sites. Moreover, the influence of events such as template-template (bupivacaine) and monomer-monomer (methacrylic acid) self-association, porogen-template interactions, and template conformational variability was revealed. The template recognition capacity of the modeled polymer system was verified by synthesis of imprinted and reference polymers and subsequent radioligand binding Analysis. Collectively, through a series of statistical analyses of molecular trajectories in conjunction with spectroscopic data it was demonstrated that an ensemble of complex structures is present in the prepolymerization mixture and that this diversity is the basis for the binding site heterogeneity observed in molecularly imprinted polymers (MIPs) prepared using the noncovalent strategy.
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| 3. |
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| 4. |
- Nicholls, Ian A., et al.
(författare)
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Theoretical and Computational Strategies for Rational Molecularly Imprinted Polymer Design
- 2009
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Ingår i: Biosensors & bioelectronics. - : Elsevier BV. - 0956-5663 .- 1873-4235. ; 25:3, s. 543-552
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Tidskriftsartikel (refereegranskat)abstract
- The further evolution of molecularly imprinted polymer science and technology necessitates the development of robust predictive tools capable of handling the complexity of molecular imprinting systems. A combination of the rapid growth in computer power over the past decade and significant software developments have opened new possibilities for simulating aspects of the complex molecular imprinting process. We present here a survey of the current status of the use of in silico-based approaches to aspects of molecular imprinting. Finally, we highlight areas where ongoing and future efforts should yield information critical to our understanding of the underlying mechanisms sufficient to permit the rational design of molecularly imprinted polymers.
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| 6. |
- Karlsson, Björn C. G., et al.
(författare)
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Molecular Insights on the Two Fluorescence Lifetimes Displayed by Warfarin from Fluorescence Anisotropy and Molecular Dynamics Studies
- 2009
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Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 113:22, s. 7945-7949
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Tidskriftsartikel (refereegranskat)abstract
- A series of steady-state fluorescence anisotropy experiments has been performed to demonstrate the presence of a deprotonated open side chain form of warfarin in organic environments. We explain the observed emission-wavelength-dependent anisotropy of warfarin in ethanol, 2-propanol, and acetonitrile due to the coexistence of neutral isomers and deprotonated open side chain forms displaying different fluorescence decay kinetics. To investigate solvent-solute interactions in more detail, a series of molecular dynamics simulations was performed to study warfarin solvation and to predict the time scale of rotational diffusion displayed by this compound. Predictions obtained provide an explanation for the nonzero values in anisotropy observed for neutral isomers of warfarin associated with the short fluorescence lifetime (tau < 0.1 ns) and for an approximately zero anisotropy observed for the deprotonated open side chain form, which is associated with the longer fluorescence lifetime (tau = 0.5-1.6 ns). Finally, we address the potential use of fluorescence anisotropy for an increased understanding of the structural diversity of warfarin in protein binding pockets.
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