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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    MRI links stem water content to stem diameter variations in transpiring trees
    Schepper, V. De; Dusschoten, D. van; Copini, P. ; Jahnke, S. ; Steppe, K. - \ 2012
    Journal of Experimental Botany 63 (2012)7. - ISSN 0022-0957 - p. 2645 - 2653.
    sap flow dynamics - sugar-transport - diurnal changes - radius changes - beech tree - xylem flow - phloem - long - anatomy - storage
    In trees, stem diameter variations are related to changes in stem water content, because internally stored water is depleted and replenished over a day. To confirm this relationship, non-invasive magnetic resonance imaging (MRI) was combined with point dendrometer measurements in three actively transpiring oak (Quercus robur L.) trees. Two of these oak trees were girdled to study the stem increment above the girdling zone. MRI images and micrographs of stem cross-sections revealed a close link between the water distribution and the anatomical features of the stem. Stem tissues with the highest amount of water were physiologically the most active ones, being the youngest differentiating xylem cells, the cambium and the youngest differentiating and conductive phloem cells. Daily changes in stem diameter corresponded well with the simultaneously MRI-measured amount of water, confirming their strong interdependence. MRI images also revealed that the amount of water in the elastic bark tissues, excluding cambium and the youngest phloem, contributed most to the daily stem diameter changes. After bark removal, an additional increase in stem diameter was measured above the girdle. This increase was attributed not only to the cambial production of new cells, but also to swelling of existing bark cells. In conclusion, the comparison of MRI and dendrometer measurements confirmed previous interpretations and applications of dendrometers and illustrates the additional and complementary information MRI can reveal regarding water relations in plants.
    MRI in soils: determination of water concent changes due to root water uptake by means of a multi-slice-multi-echo sequence (MSME)
    Pohlmeier, A. ; Vergeldt, F. ; Gerkema, E. ; As, H. van; Dusschoten, D. van; Vereecken, H. - \ 2010
    The Open Magnetic Resonance Journal 3 (2010). - ISSN 1874-7698 - p. 69 - 74.
    Root water uptake by ricinus communis (castor bean) in fine sand was investigated using MRI with multiecho sampling. Before starting the experiments the plants germinated and grew for 3 weeks in a cylindrical container with a diameter of 9 cm. Immediately before the MRI experiments started, the containers were water-saturated and sealed, so water content changes were only caused by root water uptake. In continuation of a preceding work, where we applied SPRITE we tested a multi-echo multi-slice sequence (MSME). In this approach, the water content was imaged by setting TE = 6.76 ms and nE = 128 with an isotropic resolution of 3.1mm. We calculated the water content maps by biexponential fitting of the multi-slice echo train data and normalisation on reference cuvettes filled with glass beads and 1 mM NiCl2 solution. The water content determination was validated by comparing to mean gravimetric water content measurements. By coregistration with the root architecture, visualised by a 3D fast spin echo sequence (RARE), we conclude that the largest water content changes occurred in the neighbourhood of the roots and in the upper layers of the soil.
    Optimized Rheo-optical Measurements Using Fast Fourier Transform and Oversampling
    Klein, C.O. ; Venema, P. ; Sagis, L.M.C. ; Dusschoten, D. van; Wilhelm, M. ; Spiess, H.W. ; Linden, E. van der; Rogers, S.S. ; Donald, A.M. - \ 2007
    Applied Rheology 17 (2007)4. - ISSN 1430-6395 - p. 45210 - 1-45210-7.
    polymer-solutions - rheology
    Abstract: Rheo-optics is a method that allows the analysis of optical properties, like birefringence and dichroism under steady and oscillatory shear. It is possible to correlate macroscopic mechanical responses with induced microscopic changes in the material. We describe how this method was improved several fold and implemented on a commercially available setup. However, the here presented ideas are applicable to any rheo-optical setup, based on modulation of the laser light. Additionally it does not need a lock-in amplifier and therefore reduces the costs of the setup.
    Fitting of the beat pattern observed in NMR free-induction decay signals of concentrated carbohydrate-water solutions
    Derbyshire, W. ; Bosch, M. van den; Dusschoten, D. van; MacNaughtan, W. ; Farhat, I.A. ; Hemminga, M.A. ; Mitchell, J.R. - \ 2004
    Journal of Magnetic Resonance 168 (2004)2. - ISSN 1090-7807 - p. 278 - 283.
    molecular mobility - transition - systems - glasses
    A series of mathematical functions has been used to fit the proton free-induction decays (FIDs) of concentrated carbohydrate-water samples. For the solid protons, these functions included a sine function, as well as the Fourier transforms of single and multiple Pake functions multiplied by a Gaussian broadening. The NMR signal from the mobile protons is described by an exponential function. It is found that in most cases the sine function gives a satisfactory result and provides valuable information about the second moment M-2 and the ratio of solid to mobile protons (f(s)/f(m)). A good indication for using the sine function is the presence of a beat in the FID. For high temperatures this approach breaks down, and a biexponential fit is more appropriate. If a clear dipolar splitting is observable in the NMR spectra, the Pake function (or a multiple Pake fit) should be used. In this case information about M-2 and f(s)/f(m) can also be obtained. (C) 2004 Elsevier Inc. All rights reserved.
    Fine-scale measurements of diffusivity in a microbial mat with NMR imaging
    Wieland, A. ; Dusschoten, D. van; Damgaard, L.R. ; Beer, D. de; Kuhl, M. ; As, H. van - \ 2001
    Limnology and Oceanography 46 (2001). - ISSN 0024-3590 - p. 248 - 259.
    Noninvasive 1H-nuclear magnetic resonance (NMR) imaging was used to investigate the diffusive properties of microbial mats in two dimensions. Pulsed field gradient NMR was used to acquire images of the H2O diffusion coefficient, Ds and multiecho imaging NMR was used to obtain images of the water density in two structurally different microbial mats sampled from Solar Lake (Egypt). We found a pronounced lateral and vertical variability of both water density and water diffusion coefficient, correlated with the laminated and heterogeneous distribution of microbial cells and exopolymers within the mats. The average water density varied from 0.5 to 0.9, whereas the average water diffusion coefficient ranged from 0.4 to 0.9 relative to the values obtained in the stagnant water above the mat samples. The apparent water diffusivities estimated from NMR imaging compared well to apparent O2 diffusivities measured with a diffusivity microsensor. Analysis of measured O2 concentration profiles with a diffusion-reaction model showed that both the magnitude of calculated rates and the depth distribution of calculated O2 consumption/production zones changed when the observed variations of diffusivity were taken into account. With NMR imaging, diffusivity can be determined at high spatial resolution, which can resolve inherent lateral and vertical heterogeneities found in most natural benthic systems.
    Quantification of water transport in plants with NMR imaging
    Scheenen, T. ; Jager, P.A. de; Dusschoten, D. van; As, H. van - \ 2000
    Journal of Experimental Botany 51 (2000). - ISSN 0022-0957 - p. 1751 - 1759.
    Microscopic Displacement Imaging with Pulsed Field Gradient Turbo Spin-Echo NMR
    Scheenen, T.W.J. ; Dusschoten, D. van; Jager, P.A. de; As, H. van - \ 2000
    Journal of Magnetic Resonance 142 (2000). - ISSN 1090-7807 - p. 207 - 215.
    We present a pulse sequence that enables the accurate and spatially resolved measurements of the displacements of spins in a variety of (biological) systems. The pulse sequence combines pulsed field gradient (PFG) NMR with turbo spin–echo (TSE) imaging. It is shown here that by ensuring that the phase of the echoes within a normal spin–echo train is constant, displacement propagators can be generated on a pixel-by-pixel basis. These propagators accurately describe the distribution of displacements, while imaging time is decreased by using separate phase encoding for every echo in a TSE train. Measurements at 0.47 T on two phantoms and the stem of an intact tomato plant demonstrate the capability of the sequence to measure complete and accurate propagators, encoded with 16 PFG steps, for each pixel in a 128 x 128 image (resolution 117 x 117 x 3000 m) within 17 min. Dynamic displacement studies on a physiologically relevant time resolution for plants are now within reach.
    Relation between a transition in molecular mobility and collapse phenomena in glucose-water systems
    Dries, I.J. van den; Besseling, N.A.M. ; Dusschoten, D. van; Hemminga, M.A. ; Linden, E. van der - \ 2000
    The Journal of Physical Chemistry Part B: Condensed Matter, Materials, Surfaces, Interfaces & Biophysical 104 (2000). - ISSN 1520-6106 - p. 9260 - 9266.
    In concentrated glucose glasses with water contents between 10 and 30 wt °an indication for a transition in mobility of the sugar protons above the glass transition temperature is observed, using proton magnetic resonance techniques. The first transition in mobility is positioned at the glass transition temperature while the second is about 20-30 C higher. The temperature of this second transition is found to depend on water content, resulting in a new line in the state diagram of glucose-water mixtures. In freeze-concentrated glucose glasses we find two similar transitions. We interpret the second transition as the so-called crossover temperature, where the dynamics changes from solid-like to liquid-like. In freeze-concentrated glasses an increase in the amount of ice melting per degree is observed just above the temperature of the second transition. We propose that both in concentrated and freeze-concentrated glucose glasses, this second transition relates to so-called collapse phenomena in glasses.
    Effects of Water Content and Molecular Weight on Spin Probe and Water Mobility in Malto-oligomer Glasses
    Dries, I.J. van den; Dusschoten, D. van; Hemminga, M.A. ; Linden, E. van der - \ 2000
    The Journal of Physical Chemistry Part B: Condensed Matter, Materials, Surfaces, Interfaces & Biophysical 44 (2000). - ISSN 1520-6106 - p. 10126 - 10132.
    Spin probe rotational mobility has been studied by means of saturation transfer ESR in malto-oligomer-water glasses and has been compared to water mobility as measured by 1H NMR. Increasing the water content from 10 to 30 wt ␕eads to a decrease in spin probe mobility at Tg while the water mobility increases at Tg. From FTIR data we conclude that this decrease in spin probe mobility is caused by the fact that the overall packing of water and carbohydrate molecules in the hydrogen-bonded network becomes denser upon increasing water content. From proton density measurements we conclude that the concomitant increase in mobility of water molecules is caused by the fact that the carbohydrate molecules become more separated from one another. Both water and spin probe mobility at Tg increase upon increasing the molecular weight of the malto-oligomers (ranging from glucose up to maltoheptaose), while keeping the water content constant. This can be explained by the fact that larger oligomers form less densely packed networks
    Molecular mobility in food components as studied by magnetic resonance spectroscopy
    Hemminga, M.A. ; Dries, I.J. van den; Magusin, P.C.M.M. ; Dusschoten, D. van; Berg, C. van den - \ 1999
    In: Water management in the design and the distrubution of quality foods / Roos, Y., Lancaster : Technomic
    Carbon-13 nuclear magnetic relaxation in supercooled liquid and glassy maltose
    Tromp, R.H. ; Dusschoten, D. ; Parker, R. ; Ring, S.G. - \ 1999
    Physical Chemistry Chemical Physics 1 (1999). - ISSN 1463-9076 - p. 1927 - 1931.
    13C longitudinal relaxation rates (T1-1) in highly viscous liquid and solid amorphous maltose, its mixtures with water and methanol, and also crystalline maltose monohydrate, have been measured as a function of temperature, above and below the calorimetric glass transition temperatures of the amorphous materials. From the results it is concluded that, at temperatures up to 60°C below the glass transition temperature, the carbon atoms in the exocyclic hydroxymethyl groups of maltose are more mobile than the endocyclic carbon atoms. A few percent of water is sufficient to considerably enhance amorphous maltose mobility. At temperatures close to the glass transition methanol in amorphous maltose-methanol mixtures retains a high degree of rotational mobility which is decoupled from the bulk viscosity.
    Mobility in maltose-water glasses studied with 1H NMR
    Dries, I.J. van den; Dusschoten, D. van; Hemminga, M.A. - \ 1998
    The Journal of Physical Chemistry Part B: Condensed Matter, Materials, Surfaces, Interfaces & Biophysical 102 (1998). - ISSN 1520-6106 - p. 10483 - 10489.
    Characterization of the diffusive properties of biofilms using pulsed field gradient nuclear magnetic resonance.
    Beuling, E.E. ; Dusschoten, D. van; Lens, P. ; Heuvel, J.C. van den; As, H. van; Ottengraf, S.P.P. - \ 1998
    Biotechnology and Bioengineering 60 (1998). - ISSN 0006-3592 - p. 283 - 291.
    Diffusion controlled phenomena as studied by magnetic resonance spectroscopy.
    Hemminga, M.A. ; Dries, I.J. van den; Magusin, P.C.M.M. ; Dusschoten, D. van; Berg, C. van den - \ 1998
    In: ISOPOW 7, International Symposium on Water Management in the Design and Distribution of Quality Foods: the role of water in foods; applying fundamental knowledge to the design and production of foods, Helsinki, Finland (1998)
    Mobility in glucose glasses.
    Dries, I.J. van den; Dusschoten, D. van; Hemminga, M.A. - \ 1998
    In: ISOPOW 7: International Symposium on Water Management in the Design and Distribution of Quality Foods: the role of water in foods; applying fundamental knowledge to the design and production of foods, Helsinki, Finland (1998)
    Modeling of self-diffusion and relaxation time NMR in multi-compartment systems.
    Novikov, E.G. ; Dusschoten, D. van; As, H. van - \ 1998
    Journal of Magnetic Resonance 135 (1998). - ISSN 1090-7807 - p. 522 - 528.
    Spatially resolved transport properties in radially compressed bead packings studies by PFG NMR.
    Dusschoten, D. van; Tallarek, U. ; Scheenen, T.W.J. ; Neue, U.D. ; As, H. van - \ 1998
    Magnetic Resonance Imaging 16 (1998). - ISSN 0730-725X - p. 703 - 706.
    Pulsed field gradient (PFG) multi-echo (ME) and turbo spin-echo (TSE) imaging is used to study dispersive flow in radially compressed chromatographic columns packed with porous silica beads. By using the pulsed field gradient turbo spin-echo sequence spatially resolved displacement imaging can be accelerated by a factor of 16. The positive effect of homogeneous radial packing on flow velocity and dispersion is demonstrated. Small heterogeneities of only a few percent are shown to cause changes of the dispersion coefficient of up to 50%.
    Plant growth studies using low field NMR.
    Weerd, L. van der; Ruttink, T. ; Dusschoten, D. van; Vergeldt, F.J. ; Jager, P.A. de; As, H. van - \ 1998
    In: Spatially resolved magnetic resonance: methods, materials, medicine, biology, rheology, geology, ecology, hardware / Blumer, P., Blumlich, B., Botto, R., Fukushima, E., Weinheim, Germany : Wiley-VCH - p. 473 - 479.
    Flow and transport studies in (non)consolidated porous (bio)systems consisting of solid or porous beads by PFG NMR.
    As, H. van; Palstra, W. ; Tallarek, U. ; Dusschoten, D. van - \ 1998
    Magnetic Resonance Imaging 16 (1998). - ISSN 0730-725X - p. 569 - 573.
    Mass transfer in chromatographic columns studied by PFG NMR.
    Tallarek, U. ; Dusschoten, D. van; As, H. van; Guiochon, G. ; Bayer, E. - \ 1998
    Magnetic Resonance Imaging 16 (1998). - ISSN 0730-725X - p. 699 - 702.
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