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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    1H-NMR study of the impact of high pressure and thermal processing on cell membrane integrity of onions
    Gonzalez, M.E. ; Barrett, D.M. ; McCarthy, M.J. ; Vergeldt, F.J. ; Gerkema, E. ; Matser, A.M. ; As, H. van - \ 2010
    Journal of Food Science 75 (2010)7. - ISSN 0022-1147 - p. E417 - E425.
    spin-spin relaxation - mushrooms agaricus-bisporus - nuclear-magnetic-resonance - water diffusion - lactobacillus-plantarum - vacuolar symplast - osmotic-stress - maize roots - pfg-nmr - tissue
    Proton nuclear magnetic resonance (1H-NMR) relaxometry was used to study the effects of high pressure and thermal processing on membrane permeability and cell compartmentalization, important components of plant tissue texture. High pressure treated onions were subjected to pressure levels from 20 to 200 MPa at 5 min hold time at initial temperatures of 5 and 20 °C. Thermally treated onions were exposed for 30 min at temperatures from 40 to 90 °C. Loss of membrane integrity was clearly shown by changes in transverse relaxation time (T2) of water at temperatures of 60 °C and above. Destabilization effects on membranes exposed to high pressure were observed at 200 MPa as indicated by T2 measurements and cryo-scanning electron microscopy (Cryo-SEM). T2 relaxation successfully discriminated different degrees of membrane damage based on the T2 shift of the vacuolar component. Analyses of the average water self-diffusion coefficient indicated less restricted diffusion after membrane rupture occurred in cases of severe thermal treatments. Milder processing treatments yielded lower average diffusion coefficients than the controls. 1H-NMR proved to be an effective method for quantification of cell membrane damage in onions and allowed for the comparison of different food processes based on their impact on tissue integrity
    Quantitative permeability imaging of plant tissues
    Sibgatullin, T. ; Vergeldt, F.J. ; Gerkema, E. ; As, H. van - \ 2010
    European Biophysics Journal 39 (2010)4. - ISSN 0175-7571 - p. 699 - 710.
    pulsed-field gradient - time-dependent diffusion - nuclear-magnetic-resonance - water self-diffusion - membrane-permeability - pfg nmr - osmotic-stress - porous-media - yeast-cells - echo nmr
    A method for mapping tissue permeability based on time-dependent diffusion measurements is presented. A pulsed field gradient sequence to measure the diffusion encoding time dependence of the diffusion coefficients based on the detection of stimulated spin echoes to enable long diffusion times is combined with a turbo spin echo sequence for fast NMR imaging (MRI). A fitting function is suggested to describe the time dependence of the apparent diffusion constant in porous (bio-)materials, even if the time range of the apparent diffusion coefficient is limited due to relaxation of the magnetization. The method is demonstrated by characterizing anisotropic cell dimensions and permeability on a subpixel level of different tissues of a carrot (Daucus carota) taproot in the radial and axial directions
    Quantitative NME microscopy of iron transport in methanogenic aggregates
    Vergeldt, F.J. ; Bartacek, J. ; Gerkema, E. ; Osuma, B. ; Philippi, J.G.M. ; Lens, P. ; As, H. van - \ 2009
    Diffusion Fundamentals 10 (2009). - ISSN 1862-4138 - p. 31.1 - 31.4.
    Transport of micronutrients (iron, cobalt, nickel, etc.) within biofilms matrixes such as methanogenic granules is of high importance, because these are either essential or toxic for the microorganisms living inside the biofilm. The present study demonstrates quantitative measurements of metal transport inside these biofilms using T1 weighted 3D RARE. It is shown that iron(II)-EDTA diffusion within the granule is independent of direction or the inner structure of the granules. Assuming position dependence of the spin-lattice relaxivity, Fick’s law for diffusion in a sphere can be applied to simulate the diffusion within the methanogenic granules under investigation. A relatively low diffusion coefficient of 2.5*10-11 m2·s-1 was obtained for iron diffusion within the methanogenic granule
    Magnetic resonance microscopy of iron transport in methanogenic granules
    Bartacek, J. ; Vergeldt, F.J. ; Gerkema, E. ; Jenicek, P. ; Lens, P. ; As, H. van - \ 2009
    Journal of Magnetic Resonance 200 (2009)2. - ISSN 1090-7807 - p. 303 - 312.
    heavy-metal uptake - porous-media - nmr - biofilm - sludge - diffusion - complexes - alginate - immobilization - biosorbents
    Interactions between anaerobic biofilms and heavy metals such as iron, cobalt or nickel are largely unknown. Magnetic resonance imaging (MRI) is a non-invasive method that allows in situ studies of metal transport within biofilm matrixes. The present study investigates quantitatively the penetration of iron (1.75 mM) bound to ethylenediaminetetraacetate (EDTA) into the methanogenic granules (spherical biofilm). A spatial resolution of 109 × 109 × 218 µm3 and a temporal resolution of 11 min are achieved with 3D Turbo Spin Echo (TSE) measurements. The longitudinal relaxivity, i.e. the slope the dependence of the relaxation rate (1/T1) on the concentration of paramagnetic metal ions, was used to measure temporal changes in iron concentration in the methanogenic granules. It took up to 300 min for the iron–EDTA complex ([FeEDTA]2-) to penetrate into the methanogenic granules (3–4 mm in diameter). The diffusion was equally fast in all directions with irregularities such as diffusion-facilitating channels and diffusion-resistant zones. Despite these irregularities, the overall process could be modeled using Fick’s equations for diffusion in a sphere, because immobilization of [FeEDTA]2- in the granular matrix (or the presence of a reactive barrier) was not observed. The effective diffusion coefficient (Dejf) of [FeEDTA]2- was found to be 2.8 × 10-11 m2 s-1, i.e. approximately 4% of Dejf of [FeEDTA]2- in water. The Fickian model did not correspond to the processes taking place in the core of the granule (3–5% of the total volume of the granule), where up to 25% over-saturation by iron (compare to the concentration in the bulk solution) occurred
    Most water in the tomato truss is imported through the xylem, not the phloem. An NMR flow imaging study
    Windt, C.W. ; Gerkema, E. ; As, H. van - \ 2009
    Plant Physiology 151 (2009)2. - ISSN 0032-0889 - p. 830 - 842.
    vapor-pressure deficit - membrane-permeability - transpiration flows - biological tissues - ricinus-communis - grape berries - fruit-growth - sap flow - transport - plants
    In this study, we demonstrate nuclear magnetic resonance flow imaging of xylem and phloem transport toward a developing tomato (Solanum lycopersicum) truss. During an 8-week period of growth, we measured phloem and xylem fluxes in the truss stalk, aiming to distinguish the contributions of the two transport tissues and draw up a balance between influx and efflux. It is commonly estimated that about 90% of the water reaches the fruit by the phloem and the remaining 10% by the xylem. The xylem is thought to become dysfunctional at an early stage of fruit development. However, our results do not corroborate these findings. On the contrary, we found that xylem transport into the truss remained functional throughout the 8 weeks of growth. During that time, at least 75% of the net influx into the fruit occurred through the external xylem and about 25% via the perimedullary region, which contains both phloem and xylem. About one-half of the net influx was lost due to evaporation. Halfway through truss development, a xylem backflow appeared. As the truss matured, the percentage of xylem water that circulated into the truss and out again increased in comparison with the net uptake, but no net loss of water from the truss was observed. The circulation of xylem water continued even after the fruits and pedicels were removed. This indicates that neither of them was involved in generating or conducting the circulation of sap. Only when the main axis of the peduncle was cut back did the circulation stop
    The effect of rice kernel microstructure on cooking behaviour: A combined µ-CT and MRI study
    Mohoric, A. ; Vergeldt, F.J. ; Gerkema, E. ; Dalen, G. van; Doel, L.R. van den; Vliet, L.J. van; As, H. van; Duynhoven, J.P.M. van - \ 2009
    Food Chemistry 115 (2009)4. - ISSN 0308-8146 - p. 1491 - 1499.
    magnetic-resonance - water migration - puffed rice - nmr - grain - gelatinization - starch - profile - flour - model
    In order to establish the underlying structure-dependent principles of instant cooking rice, a detailed investigation was carried out on rice kernels that were processed in eight different manners. Milling, parboiling, wet-processing and extrusion were applied, with and without a subsequent puffing treatment. The mesostructure of the rice kernels was examined by DSC and XRD, and the microstructure by µ-CT. Hydration behaviour during cooking was studied by MRI in a real-time manner. Based on simple descriptive models, three different classes of cooking behaviour can be discerned. The water ingress profiles during cooking of these three classes matched well with simulations from a model that was based on water demand of the starch mass and the porous microstructure of the kernels. Thus a clear correlation between meso/microstructure of a rice kernel and the cooking behaviour has been established
    NMR microimaging of fluid flow in model string-type reactors
    Koptyug, I.V. ; Kovtunov, K.V. ; Gerkema, E. ; Kiwi-Minskerc, L. ; Sagdeev, R.Z. - \ 2007
    Chemical Engineering Science 62 (2007)16. - ISSN 0009-2509 - p. 4459 - 4468.
    field-gradient nmr - velocity exchange spectroscopy - magnetic-resonance - gas-flow - pfg-nmr - numerical-simulation - spatial correlations - 2-phase flow - porous-media - dispersion
    Magnetic resonance microimaging (MRM) was employed to obtain quantitative velocity maps of water flowing in the channels possessing unconventional cross-section shapes formed by a bundle of parallel fibers within a tubular string-type reactor. The maps obtained demonstrate the presence of large amounts of an almost stagnant liquid in the stretched corners of the cross-sections representing distorted triangles or squares. This fact together with the irregularity of the filaments packing in the model string-type reactor was demonstrated to lead to a broad residence time distributions (RTDs) for liquid flow. Next, the pulsed field gradient NMR (PFG NMR) technique was employed to compare transport of water with that of butane gas in the same model string-type reactor. The experimentally measured average propagators (travel distance probability density functions) have demonstrated that Taylor dispersion can lead to much better RTDs for gas as compared to liquid in channels with sub-millimeter equivalent diameters. The PFG NMR data were compared with the RTD obtained using the conventional tracer time-of-flight transient response method. It is concluded that due to the differences in the quantities actually measured by the two techniques, and the significant differences in the measurement length scales (microns to 1¿2 cm for NMR/MRM, tens of centimeters for transient response methods), there is no reliable way of directly comparing these results. The information obtained by NMR/MRM and more conventional techniques such as time-of-flight should be considered as complementary. In particular, NMR/MRM can reveal the reasons for the observed overall reactor performance by providing access to the transport processes on short length scales inside the reactor and by revealing structure¿transport interrelations.
    0.7 and 3 T MRI and sap flow in intact trees: xylem and phloem in action
    Homan, N. ; Windt, C.W. ; Vergeldt, F.J. ; Gerkema, E. ; As, H. van - \ 2007
    Applied Magnetic Resonance 32 (2007)1-2. - ISSN 0937-9347 - p. 157 - 170.
    nuclear-magnetic-resonance - distance water transport - noninvasive measurement - ricinus-communis - plants - nmr - long - microscopy
    Dedicated magnetic resonance imaging (MRI) hardware is described that allows imaging of sap flow in intact trees with a maximal trunk diameter of 4 cm and height of several meters. This setup is used to investigate xylem and phloem flow in an intact tree quantitatively. Due to the fragile gradients in pressure present in both xylem and phloem, methods to study xylem and phloem transport must be minimally invasive. MRI flow imaging by means of this hardware certainly fulfils this condition. Flow is quantified in terms of (averaged) velocity, volume flow (flux) and flow conducting area, either in imaging mode or as a nonspatially resolved total. Results obtained for one tree, imaged at two different field strengths (0.7 and 3 T), are compared. An overall shortening of observed T2 values is manifest going from 0.7 to 3 T. Although some susceptibility artefacts may be present at 3 T, the results are still reliable and the gain in sensitivity results in shorter measurement time (or higher signal-to-noise ratio) with respect to the 0.7 T system. The results demonstrate that by use of dedicated hardware, xylem and phloem flow and its mutual interaction, can be studied in intact trees in relation to the water balance and in response to environmental (stress) conditions
    Flow MRI teaches us some lessons on hydraulic conductivity in trees
    As, H. van; Windt, C.W. ; Homan, N. ; Gerkema, E. ; Vergeldt, F.J. - \ 2006
    The effect of porous structure of rice on the hydration rate investigated by MRI
    Mohoric, A. ; Duynhoven, J.P.M. van; Dalen, G. van; Vergeldt, F.J. ; Gerkema, E. ; Jager, P.A. de; As, H. van - \ 2005
    - 6 p.
    Solid-state 27 Al MRI and NMR thermometry for catalytic applications with conventional (liquids) MRI instrumentation and techniques
    Koptyug, I.V. ; Sagdeev, D.R. ; Gerkema, E. ; As, H. van; Sagdeev, R.Z. - \ 2005
    Journal of Magnetic Resonance 175 (2005)1. - ISSN 1090-7807 - p. 21 - 29.
    resonance - gradient - resolution - hydrogenation - aluminas - contrast - filters - pellet - phase
    Multidimensional images of Al2O3 pellets, cordierite monolith, glass tube, polycrystalline V2O5 and other materials have been detected by 27Al, 51V, and 23Na NMR imaging using techniques and instrumentation conventionally employed for imaging of liquids. These results demonstrate that, contrary to the widely accepted opinion, imaging of ¿rigid¿ solids does not necessarily require utilization of solid state NMR imaging approaches, pulse sequences and hardware even for quadrupolar nuclei which exhibit line widths in excess of 100 kHz, such as 51V in polycrystalline V2O5. It is further demonstrated that both 27Al NMR signal intensity and spin-lattice relaxation time decrease with increasing temperature and thus can potentially serve as temperature sensitive parameters for spatially resolved NMR thermometry.
    Magnetic resonance imaging of single rice kernels during cooking
    Mohoric, A. ; Vergeldt, F.J. ; Gerkema, E. ; Jager, P.A. de; Duynhoven, J.P.M. van; Dalen, G. van; As, H. van - \ 2004
    Journal of Magnetic Resonance 171 (2004)1. - ISSN 1090-7807 - p. 157 - 162.
    water migration - nmr - grain - gelatinization - starch - model
    The RARE imaging method was used to monitor the cooking of single rice kernels in real time and with high spatial resolution in three dimensions. The imaging sequence is optimized for rapid acquisition of signals with short relaxation times using centered out RARE. Short scan time and high spatial resolution are critical factors in the investigation of the cooking behavior of rice kernels since time and spatial averaging may lead to erroneous results. The results are confirming the general pattern of moisture ingress that has been suspected from previous (more limited) studies. Water uptake as determined by analysis of the MRI time series recorded during cooking compares well with gravimetric studies. This allows using these real-time MRI data for developing and validating models that describe the effect of kernel microstructure on its cooking behavior. (C) 2004 Elsevier Inc. All rights reserved.
    Photopyroelectric Measurement of Thermal Diffusivity of Industrial Polymers : Low Density Polyethylene and Polyvinyl Chloride Foils
    Favier, J.P. ; Dadarlat, D. ; Bicanic, D. ; Riezebos, K.J. ; Berg, C. van den; Gerkema, E. - \ 1999
    Instrumentation Science and Technology (1999)27. - ISSN 1073-9149 - p. 275 - 286.
    Monitoring the Severity of the Heat Treatment in Pressure Toasted Peas and Soybeans by Means of the Photoacoustic and NIRReflectance Spectroscopies
    Doka, O. ; Bicanic, D. ; Goelema, J. ; Gerkema, E. ; Frankhuizen, R. - \ 1999
    In: Photoacoustic and Photothermal Phenomena : Proceedings of the 10th Topical International Conference on Photoacoustic and Photothermal Phenomena, AIP Conference Proceedings 463, Rome, Italy, August 24-26, 1998 / Scudieri F. and BertolottiM.(eds.). - Woodburry, New York, US : American Institute of Physics Press, 1999. - ISBN 1-56396-805-3 - p. 658 - 660.
    Infrared Photothermal Spectroscopy in the Science of Human Nutrition
    Bicanic, D. ; Fink, T. ; Franko, M. ; Mocnik, G. ; Bovenkamp, P. van de; Veldhuizen, A. van; Gerkema, E. - \ 1999
    In: Photoacoustic and Photothermal Phenomena / Scudieri, F., Bertolotti, M., Woodburry, New York : American Institute of Physics (American Institute of Physics (AIP) Conference Proceedings 463) - ISBN 9781563968051 - p. 637 - 639.
    Application of infrared photothermal spectroscopy in human nutrition.
    Bicanic, D. ; Fink, T. ; Franko, M. ; Bovenkamp, P. van de; Veldhuizen, B. van; Gerkema, E. - \ 1998
    In: 10th International Conference on Photoacoustic and Photothermal Phenomena, Rome, The Netherlands - p. 513 - 514.
    Photopyroelectric study of thermal properties of diluted and concentrated sugar systems: application to aqueous solutions of maltose, glucose and maltodextrine, and to honey of varying moisture content.
    Dadarlat, D. ; Riezebos, K.J. ; Bicanic, D. ; Berg, C. van den; Gerkema, E. ; Surducan, V. - \ 1998
    Advances in Food Sciences 20 (1998). - ISSN 1431-7737 - p. 27 - 33.
    Infrared transient thermography for non-contact, nondestructive inspection of whole and dissected apples and of cherry tomatoes at different maturity stages.
    Offermann, S. ; Bicanic, D. ; Krapez, J.C. ; Balageas, D. ; Gerkema, E. ; Chirtoc, M. ; Egee, M. ; Keijzer, K. ; Jalink, H. - \ 1998
    Instrumentation Science and Technology 26 (1998). - ISSN 1073-9149 - p. 145 - 155.
    Photoacoustic and photothermal methods as a tool to aid authenticity tests and quality assessment of foods
    Bicanic, D. ; Dóka, O. ; Gibkes, J. ; Offermann, S. ; Dadarlat, D. ; Keyzer, C. ; Long, G. ; Fink, T. ; Gerkema, E. ; Bein, B. ; Boekel, T. van; Jalink, H. - \ 1996
    Progress in Natural Science 6 (1996). - ISSN 1002-0071 - p. 573 - 576.
    Applications of photoacoustic and photothermal non-contact methods in the selected areas of environmental and agricultural sciences.
    Bicanic, D. ; Franko, M. ; Gibkes, J. ; Gerkema, E. ; Favier, J.P. ; Jalink, H. - \ 1996
    In: Progress in photoacoustic and photothermal science: Life and earth sciences / Mandelis, A., - p. 131 - 180.
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