@article{CaiToetzkeKaestneretal.2022,
  author    = {Cai, Gaochao and T{\"o}tzke, Christian and Kaestner, Anders and Ahmed, Mutez Ali},
  title     = {Quantification of root water uptake and redistribution using neutron imaging: a review and future directions},
  series = {The plant journal},
  volume    = {111},
  journal   = {The plant journal},
  number    = {2},
  publisher = {Wiley-Blackwell},
  address   = {Oxford [u.a.]},
  issn      = {0960-7412},
  doi       = {10.1111/tpj.15839},
  pages     = {348 -- 359},
  year      = {2022},
  abstract  = {Quantifying root water uptake is essential to understanding plant water use and responses to different environmental conditions. However, non-destructive measurement of water transport and related hydraulics in the soil-root system remains a challenge. Neutron imaging, with its high sensitivity to hydrogen, has become an unparalleled tool to visualize and quantify root water uptake in vivo. In combination with isotopes (e.g., deuterated water) and a diffusion-convection model, root water uptake and hydraulic redistribution in root and soil can be quantified. Here, we review recent advances in utilizing neutron imaging to visualize and quantify root water uptake, hydraulic redistribution in roots and soil, and root hydraulic properties of different plant species. Under uniform soil moisture distributions, neutron radiographic studies have shown that water uptake was not uniform along the root and depended on both root type and age. For both tap (e.g., lupine [Lupinus albus L.]) and fibrous (e.g., maize [Zea mays L.]) root systems, water was mainly taken up through lateral roots. In mature maize, the location of water uptake shifted from seminal roots and their laterals to crown/nodal roots and their laterals. Under non-uniform soil moisture distributions, part of the water taken up during the daytime maintained the growth of crown/nodal roots in the upper, drier soil layers. Ultra-fast neutron tomography provides new insights into 3D water movement in soil and roots. We discuss the limitations of using neutron imaging and propose future directions to utilize neutron imaging to advance our understanding of root water uptake and soil-root interactions.},
  language  = {en}
}
@article{RudolphMohrBereswillToetzkeetal.2021,
  author    = {Rudolph-Mohr, Nicole and Bereswill, Sarah and T{\"o}tzke, Christian and Kardjilov, Nikolay and Oswald, Sascha},
  title     = {Neutron computed laminography yields 3D root system architecture and complements investigations of spatiotemporal rhizosphere patterns},
  series = {Plant and soil},
  volume    = {469},
  journal   = {Plant and soil},
  number    = {1-2},
  publisher = {Springer},
  address   = {Dordrecht},
  issn      = {0032-079X},
  doi       = {10.1007/s11104-021-05120-7},
  pages     = {489 -- 501},
  year      = {2021},
  abstract  = {Purpose Root growth, respiration, water uptake as well as root exudation induce biogeochemical patterns in the rhizosphere that can change dynamically over time. Our aim is to develop a method that provides complementary information on 3D root system architecture and biogeochemical gradients around the roots needed for the quantitative description of rhizosphere processes. Methods We captured for the first time the root system architecture of maize plants grown in rectangular rhizotrons in 3D using neutron computed laminography (NCL). Simultaneously, we measured pH and oxygen concentration using fluorescent optodes and the 2D soil water distribution by means of neutron radiography. We co-registered the 3D laminography data with the 2D oxygen and pH maps to analyze the sensor signal as a function of the distance between the roots and the optode. Results The 3D root system architecture was successfully segmented from the laminographic data. We found that exudation of roots in up to 2 mm distance to the pH optode induced patterns of local acidification or alkalization. Over time, oxygen gradients in the rhizosphere emerged for roots up to a distance of 7.5 mm. Conclusion Neutron computed laminography allows for a three-dimensional investigation of root systems grown in laterally extended rhizotrons as the ones designed for 2D optode imaging studies. The 3D information on root position within the rhizotrons derived by NCL explained measured 2D oxygen and pH distribution. The presented new combination of 3D and 2D imaging methods facilitates systematical investigations of a wide range of dynamic processes in the rhizosphere.},
  language  = {en}
}
@article{ToetzkeOswaldHilgeretal.2021,
  author    = {T{\"o}tzke, Christian and Oswald, Sascha and Hilger, Andr{\´e} and Kardjilov, Nikolay},
  title     = {Non-invasive detection and localization of microplastic particles in a sandy sediment by complementary neutron and X-ray tomography},
  series = {Journal of soils and sediments : protection, risk assessment and remediation},
  volume    = {21},
  journal   = {Journal of soils and sediments : protection, risk assessment and remediation},
  number    = {3},
  publisher = {Springer},
  address   = {Berlin ; Heidelberg},
  issn      = {1439-0108},
  doi       = {10.1007/s11368-021-02882-6},
  pages     = {1476 -- 1487},
  year      = {2021},
  abstract  = {Purpose Microplastics have become a ubiquitous pollutant in marine, terrestrial and freshwater systems that seriously affects aquatic and terrestrial ecosystems. Common methods for analysing microplastic abundance in soil or sediments are based on destructive sampling or involve destructive sample processing. Thus, substantial information about local distribution of microplastics is inevitably lost. Methods Tomographic methods have been explored in our study as they can help to overcome this limitation because they allow the analysis of the sample structure while maintaining its integrity. However, this capability has not yet been exploited for detection of environmental microplastics. We present a bimodal 3D imaging approach capable to detect microplastics in soil or sediment cores non-destructively. Results In a first pilot study, we demonstrate the unique potential of neutrons to sense and localize microplastic particles in sandy sediment. The complementary application of X-rays allows mineral grains to be discriminated from microplastic particles. Additionally, it yields detailed information on the 3D surroundings of each microplastic particle, which supports its size and shape determination. Conclusion The procedure we developed is able to identify microplastic particles with diameters of approximately 1 mm in a sandy soil. It also allows characterisation of the shape of the microplastic particles as well as the microstructure of the soil and sediment sample as depositional background information. Transferring this approach to environmental samples presents the opportunity to gain insights of the exact distribution of microplastics as well as their past deposition, deterioration and translocation processes.},
  language  = {en}
}
@article{ToetzkeCermakNadezhdinaetal.2017,
  author    = {T{\"o}tzke, Christian and Cermak, Jan and Nadezhdina, Nadezhda and Tributsch, Helmut},
  title     = {Electrochemical in-situ studies of solar mediated oxygen transport and turnover dynamics in a tree trunk of Tilia cordata},
  series = {iForest - Biogeosciences and Forestry},
  volume    = {10},
  journal   = {iForest - Biogeosciences and Forestry},
  number    = {2},
  publisher = {SISEF - The Italian Society of Silviculture and Forest Ecology},
  address   = {Potenza},
  issn      = {1971-7458},
  doi       = {10.3832/ifor1681-010},
  pages     = {355 -- 361},
  year      = {2017},
  abstract  = {Platinum electrodes were implanted into the xylem of a lime tree (Tilia cordata) stem and solar- induced electrochemical potential differences of up to 120 mV were measured during the vegetative period and up to 30 mV in winter. The time dependent curves were found to be delayed with respect to solar radiation, sap flow activity, temperature and vapor pressure deficit. A general equation for the potential difference was derived and simplified by analyzing the effect of temperature and tensile strength. The potential determining influence of oxygen concentration on the respective location of the platinum electrode was identified as the principal phenomenon measured. A systematic analysis and investigation of the observed periodic oxygen concentration signals promises new information on sap flow, oxygen diffusion through tree tissues and on oxygen consumption related to the energy turnover in tree tissues.},
  language  = {en}
}
@article{ToetzkeKardjilovHilgeretal.2021,
  author    = {T{\"o}tzke, Christian and Kardjilov, Nikolay and Hilger, Andr{\´e} and Rudolph-Mohr, Nicole and Manke, Ingo and Oswald, Sascha},
  title     = {Three-dimensional in vivo analysis of water uptake and translocation in maize roots by fast neutron tomography},
  series = {Scientific Reports},
  volume    = {11},
  journal   = {Scientific Reports},
  publisher = {Macmillan Publishers Limited},
  address   = {London},
  issn      = {2045-2322},
  doi       = {10.1038/s41598-021-90062-4},
  pages     = {10},
  year      = {2021},
  abstract  = {Root water uptake is an essential process for terrestrial plants that strongly affects the spatiotemporal distribution of water in vegetated soil. Fast neutron tomography is a recently established non-invasive imaging technique capable to capture the 3D architecture of root systems in situ and even allows for tracking of three-dimensional water flow in soil and roots. We present an in vivo analysis of local water uptake and transport by roots of soil-grown maize plants—for the first time measured in a three-dimensional time-resolved manner. Using deuterated water as tracer in infiltration experiments, we visualized soil imbibition, local root uptake, and tracked the transport of deuterated water throughout the fibrous root system for a day and night situation. This revealed significant differences in water transport between different root types. The primary root was the preferred water transport path in the 13-days-old plants while seminal roots of comparable size and length contributed little to plant water supply. The results underline the unique potential of fast neutron tomography to provide time-resolved 3D in vivo information on the water uptake and transport dynamics of plant root systems, thus contributing to a better understanding of the complex interactions of plant, soil and water.},
  language  = {en}
}
@misc{ToetzkeKardjilovHilgeretal.2021,
  author    = {T{\"o}tzke, Christian and Kardjilov, Nikolay and Hilger, Andr{\´e} and Rudolph-Mohr, Nicole and Manke, Ingo and Oswald, Sascha},
  title     = {Three-dimensional in vivo analysis of water uptake and translocation in maize roots by fast neutron tomography},
  series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-52991},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-529915},
  pages     = {12},
  year      = {2021},
  abstract  = {Root water uptake is an essential process for terrestrial plants that strongly affects the spatiotemporal distribution of water in vegetated soil. Fast neutron tomography is a recently established non-invasive imaging technique capable to capture the 3D architecture of root systems in situ and even allows for tracking of three-dimensional water flow in soil and roots. We present an in vivo analysis of local water uptake and transport by roots of soil-grown maize plants—for the first time measured in a three-dimensional time-resolved manner. Using deuterated water as tracer in infiltration experiments, we visualized soil imbibition, local root uptake, and tracked the transport of deuterated water throughout the fibrous root system for a day and night situation. This revealed significant differences in water transport between different root types. The primary root was the preferred water transport path in the 13-days-old plants while seminal roots of comparable size and length contributed little to plant water supply. The results underline the unique potential of fast neutron tomography to provide time-resolved 3D in vivo information on the water uptake and transport dynamics of plant root systems, thus contributing to a better understanding of the complex interactions of plant, soil and water.},
  language  = {en}
}
@article{HaberPohlmeierToetzkeOswaldetal.2017,
  author    = {Haber-Pohlmeier, Sabina and T{\"o}tzke, Christian and Oswald, Sascha and Lehmann, Eberhard and Bl{\"u}mich, Bernhard and Pohlmeier, Andreas},
  title     = {Imaging of root zone processes using MRI T-1 mapping},
  series = {Microporous and mesoporous materials : zeolites, clays, carbons and related materials},
  volume    = {269},
  journal   = {Microporous and mesoporous materials : zeolites, clays, carbons and related materials},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {1387-1811},
  doi       = {10.1016/j.micromeso.2017.10.046},
  pages     = {43 -- 46},
  year      = {2017},
  abstract  = {Noninvasive imaging in the root soil compartment is mandatory for improving knowledge about root soil interactions and uptake processes which eventually control crop growth and productivity. Here we propose a method of MRI T-1 relaxation mapping to investigate water uptake patterns, and as second example, in combination with neutron tomography (NT), property changes in the rhizosphere. The first part demonstrates quantification of solute enrichment by advective transport to the roots due to water uptake. This accumulation is counterbalanced by net downward flow and dispersive spreading. One can furthermore discriminate between zones of high accumulation patterns and zones with much less enrichment. This behavior persists over days. The second part presents the novel combination of MRI with neutron tomography to couple static, proton density information of roots and their interface to the surrounding soil with information about the local water dynamics, reflected by NMR relaxation times. The root soil interface of a broad bean plant is characterized by slightly increasing MRI and NT signal intensity but decreasing T-1 relaxation time indicating locally changed soil properties.},
  language  = {en}
}
@article{ToetzkeKardjilovLenoiretal.2019,
  author    = {T{\"o}tzke, Christian and Kardjilov, Nikolay and Lenoir, Nicolas and Manke, Ingo and Oswald, Sascha and Tengattini, Alessandro},
  title     = {What comes NeXT?},
  series = {Optics express : the international electronic journal of optics},
  volume    = {27},
  journal   = {Optics express : the international electronic journal of optics},
  number    = {20},
  publisher = {Optical Society of America},
  address   = {Washington},
  issn      = {1094-4087},
  doi       = {10.1364/OE.27.028640},
  pages     = {28640 -- 28648},
  year      = {2019},
  abstract  = {Here, we report on a new record in the acquisition time for fast neutron tomography. With an optimized imaging setup, it was possible to acquire single radiographic projection images with 10 ms and full tomographies with 155 projections images and a physical spatial resolution of 200 mu m within 1.5 s. This is about 6.7 times faster than the current record. We used the technique to investigate the water infiltration in the soil with a living lupine root system. The fast imaging setup will be part of the future NeXT instrument at ILL in Grenoble with a great field of possible future applications. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement},
  language  = {en}
}
@article{HaberPohlmeierToetzkeLehmannetal.2019,
  author    = {Haber-Pohlmeier, Sabina and T{\"o}tzke, Christian and Lehmann, E. and Kardjilov, Nikolay and Pohlmeier, A. and Oswald, Sascha},
  title     = {Combination of magnetic resonance imaging and neutron computed tomography for three-dimensional rhizosphere imaging},
  series = {Vadose zone journal},
  volume    = {18},
  journal   = {Vadose zone journal},
  number    = {1},
  publisher = {Soil Science Society of America},
  address   = {Madison},
  issn      = {1539-1663},
  doi       = {10.2136/vzj2018.09.0166},
  pages     = {11},
  year      = {2019},
  abstract  = {Core Ideas 3D MRI relaxation time maps reflect water mobility in root, rhizosphere, and soil. 3D NCT water content maps of the same plant complement relaxation time maps. The relaxation time T1 decreases from soil to root, whereas water content increases. Parameters together indicate modification of rhizosphere pore space by gel phase. The zone of reduced T1 corresponds to the zone remaining dry after rewetting. In situ investigations of the rhizosphere require high-resolution imaging techniques, which allow a look into the optically opaque soil compartment. We present the novel combination of magnetic resonance imaging (MRI) and neutron computed tomography (NCT) to achieve synergistic information such as water mobility in terms of three-dimensional (3D) relaxation time maps and total water content maps. Besides a stationary MRI scanner for relaxation time mapping, we used a transportable MRI system on site in the NCT facility to capture rhizosphere properties before desiccation and after subsequent rewetting. First, we addressed two questions using water-filled test capillaries between 0.1 and 5 mm: which root diameters can still be detected by both methods, and to what extent are defined interfaces blurred by these imaging techniques? Going to real root system architecture, we demonstrated the sensitivity of the transportable MRI device by co-registration with NCT and additional validation using X-ray computed tomography. Under saturated conditions, we observed for the rhizosphere in situ a zone with shorter T1 relaxation time across a distance of about 1 mm that was not caused by reduced water content, as proven by successive NCT measurements. We conclude that the effective pore size in the pore network had changed, induced by a gel phase. After rewetting, NCT images showed a dry zone persisting while the MRI intensity inside the root increased considerably, indicating water uptake from the surrounding bulk soil through the still hydrophobic rhizosphere. Overall, combining NCT and MRI allows a more detailed analysis of the rhizosphere's functioning.},
  language  = {en}
}
@article{HerppichMartinToetzkeetal.2019,
  author    = {Herppich, Werner B. and Martin, Craig E. and T{\"o}tzke, Christian and Manke, Ingo and Kardjilov, Nikolay},
  title     = {External water transport is more important than vascular transport in the extreme atmospheric epiphyte Tillandsia usneoides (Spanish moss)},
  series = {Plant, cell \& environment : cell physiology, whole-plant physiology, community physiology},
  volume    = {42},
  journal   = {Plant, cell \& environment : cell physiology, whole-plant physiology, community physiology},
  number    = {5},
  publisher = {Wiley},
  address   = {Hoboken},
  issn      = {0140-7791},
  doi       = {10.1111/pce.13496},
  pages     = {1645 -- 1656},
  year      = {2019},
  abstract  = {Most epiphytic bromeliads, especially those in the genus Tillandsia, lack functional roots and rely on the absorption of water and nutrients by large, multicellular trichomes on the epidermal surfaces of leaves and stems. Another important function of these structures is the spread of water over the epidermal surface by capillary action between trichome "wings" and epidermal surface. Although critical for the ultimate absorption by these plants, understanding of this function of trichomes is primarily based on light microscope observations. To better understand this phenomenon, the distribution of water was followed by its attenuation of cold neutrons following application of H2O to the cut end of Tillandsia usneoides shoots. Experiments confirmed the spread of added water on the external surfaces of this "atmospheric" epiphyte. In a morphologically and physiologically similar plant lacking epidermal trichomes, water added to the cut end of a shoot clearly moved via its internal xylem and not on its epidermis. Thus, in T. usneoides, water moves primarily by capillarity among the overlapping trichomes forming a dense indumentum on shoot surfaces, while internal vascular water movement is less likely. T. usneoides, occupying xeric microhabitats, benefits from reduction of water losses by low-shoot xylem hydraulic conductivities.},
  language  = {en}
}
@article{ToetzkeGaiselmannOsenbergetal.2016,
  author    = {T{\"o}tzke, Christian and Gaiselmann, G. and Osenberg, M. and Arlt, T. and Mark{\"o}tter, H. and Hilger, A. and Kupsch, Andreas and M{\"u}ller, B. R. and Schmidt, V. and Lehnert, W. and Manke, Ingo},
  title     = {Influence of hydrophobic treatment on the structure of compressed gas diffusion layers},
  series = {Journal of power sources : the international journal on the science and technology of electrochemical energy systems},
  volume    = {324},
  journal   = {Journal of power sources : the international journal on the science and technology of electrochemical energy systems},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0378-7753},
  doi       = {10.1016/j.jpowsour.2016.05.118},
  pages     = {625 -- 636},
  year      = {2016},
  abstract  = {Carbon fiber based felt materials are widely used as gas diffusion layer (GDL) in fuel cells. Their transport properties can be adjusted by adding hydrophobic agents such as polytetrafluoroethylene (PTFE). We present a synchrotron X-ray tomographic study on the felt material Freudenberg H2315 with different PIPE finishing. In this study, we analyze changes in microstructure and shape of GDLs at increasing degree of compression which are related to their specific PTFE load. A dedicated compression device mimicking the channel-land pattern of the flowfield is used to reproduce the inhomogeneous compression found in a fuel cell. Transport relevant geometrical parameters such as porosity, pore size distribution and geometric tortuosity are calculated and consequences for media transport discussed. PTFE finishing results in a marked change of shape of compressed GDLs: surface is smoothed and the invasion of GDL fibers into the flow field channel strongly mitigated. Furthermore, the PTFE impacts the microstructure of the compressed GDL. The number of available wide transport paths is significantly increased as compared to the untreated material. These changes improve the transport capacity liquid water through the GDL and promote the discharge of liquid water droplets from the cell. (C) 2016 Elsevier B.V. All rights reserved.},
  language  = {en}
}
@article{FazeliHinebaughFishmanetal.2016,
  author    = {Fazeli, Mohammadreza and Hinebaugh, James and Fishman, Zachary and T{\"o}tzke, Christian and Lehnert, Werner and Manke, Ingo and Bazylak, Aimy},
  title     = {Pore network modeling to explore the effects of compression on multiphase transport in polymer electrolyte membrane fuel cell gas diffusion layers},
  series = {Journal of power sources : the international journal on the science and technology of electrochemical energy systems},
  volume    = {335},
  journal   = {Journal of power sources : the international journal on the science and technology of electrochemical energy systems},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0378-7753},
  doi       = {10.1016/j.jpowsour.2016.10.039},
  pages     = {162 -- 171},
  year      = {2016},
  abstract  = {Understanding how compression affects the distribution of liquid water and gaseous oxygen in the polymer electrolyte membrane fuel cell gas diffusion layer (GDL) is vital for informing the design of improved porous materials for effective water management strategies. Pore networks extracted from synchrotron-based micro-computed tomography images of compressed GDLs were employed to simulate liquid water transport in GDL materials over a range of compression pressures. The oxygen transport resistance was predicted for each sample under dry and partially saturated conditions. A favorable GDL compression value for a preferred liquid water distribution and oxygen diffusion was found for Toray TGP-H-090 (10\%), yet an optimum compression value was not recognized for SGL Sigracet 25BC. SGL Sigracet 25BC exhibited lower transport resistance values compared to Toray TGP-H-090, and this is attributed to the additional diffusion pathways provided by the microporous layer (MPL), an effect that is particularly significant under partially saturated conditions. (C) 2016 Elsevier B.V. All rights reserved.},
  language  = {en}
}
@misc{ToetzkeKardjilovMankeetal.2017,
  author    = {T{\"o}tzke, Christian and Kardjilov, Nikolay and Manke, Ingo and Oswald, Sascha},
  title     = {Capturing 3D Water Flow in Rooted Soil by Ultra-fast Neutron Tomography},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-402237},
  pages     = {9},
  year      = {2017},
  abstract  = {Water infiltration in soil is not only affected by the inherent heterogeneities of soil, but even more by the interaction with plant roots and their water uptake. Neutron tomography is a unique non-invasive 3D tool to visualize plant root systems together with the soil water distribution in situ. So far, acquisition times in the range of hours have been the major limitation for imaging 3D water dynamics. Implementing an alternative acquisition procedure we boosted the speed of acquisition capturing an entire tomogram within 10 s. This allows, for the first time, tracking of a water front ascending in a rooted soil column upon infiltration of deuterated water time-resolved in 3D. Image quality and resolution could be sustained to a level allowing for capturing the root system in high detail. Good signal-to-noise ratio and contrast were the key to visualize dynamic changes in water content and to localize the root uptake. We demonstrated the ability of ultra-fast tomography to quantitatively image quick changes of water content in the rhizosphere and outlined the value of such imaging data for 3D water uptake modelling. The presented method paves the way for time-resolved studies of various 3D flow and transport phenomena in porous systems},
  language  = {en}
}
@article{ToetzkeKardjilovMankeetal.2017,
  author    = {T{\"o}tzke, Christian and Kardjilov, Nikolay and Manke, Ingo and Oswald, Sascha},
  title     = {Capturing 3D Water Flow in Rooted Soil by Ultra-fast Neutron Tomography},
  series = {Scientific reports},
  volume    = {7},
  journal   = {Scientific reports},
  publisher = {Macmillan Publishers Limited},
  address   = {London},
  issn      = {2045-2322},
  doi       = {10.1038/s41598-017-06046-w},
  year      = {2017},
  abstract  = {Water infiltration in soil is not only affected by the inherent heterogeneities of soil, but even more by the interaction with plant roots and their water uptake. Neutron tomography is a unique non-invasive 3D tool to visualize plant root systems together with the soil water distribution in situ. So far, acquisition times in the range of hours have been the major limitation for imaging 3D water dynamics. Implementing an alternative acquisition procedure we boosted the speed of acquisition capturing an entire tomogram within 10 s. This allows, for the first time, tracking of a water front ascending in a rooted soil column upon infiltration of deuterated water time-resolved in 3D. Image quality and resolution could be sustained to a level allowing for capturing the root system in high detail. Good signal-to-noise ratio and contrast were the key to visualize dynamic changes in water content and to localize the root uptake. We demonstrated the ability of ultra-fast tomography to quantitatively image quick changes of water content in the rhizosphere and outlined the value of such imaging data for 3D water uptake modelling. The presented method paves the way for time-resolved studies of various 3D flow and transport phenomena in porous systems.},
  language  = {en}
}
@article{ToetzkeMankeGaiselmannetal.2015,
  author    = {T{\"o}tzke, Christian and Manke, Ingo and Gaiselmann, Gerd and Bohner, John and M{\"u}ller, Bernd R. and Kupsch, Andreas and Hentschel, Manfred P. and Schmidt, Volker and Banhart, Jens and Lehnert, Werner},
  title     = {A dedicated compression device for high resolution X-ray tomography of compressed gas diffusion layers},
  series = {Review of scientific instruments : a monthly journal devoted to scientific instruments, apparatus, and techniques},
  volume    = {86},
  journal   = {Review of scientific instruments : a monthly journal devoted to scientific instruments, apparatus, and techniques},
  number    = {4},
  publisher = {American Institute of Physics},
  address   = {Melville},
  issn      = {0034-6748},
  doi       = {10.1063/1.4918291},
  pages     = {6},
  year      = {2015},
  abstract  = {We present an experimental approach to study the three-dimensional microstructure of gas diffusion layer (GDL) materials under realistic compression conditions. A dedicated compression device was designed that allows for synchrotron-tomographic investigation of circular samples under well-defined compression conditions. The tomographic data provide the experimental basis for stochastic modeling of nonwoven GDL materials. A plain compression tool is used to study the fiber courses in the material at different compression stages. Transport relevant geometrical parameters, such as porosity, pore size, and tortuosity distributions, are exemplarily evaluated for a GDL sample in the uncompressed state and for a compression of 30 vol.\%. To mimic the geometry of the flow-field, we employed a compression punch with an integrated channel-rib-profile. It turned out that the GDL material is homogeneously compressed under the ribs, however, much less compressed underneath the channel. GDL fibers extend far into the channel volume where they might interfere with the convective gas transport and the removal of liquid water from the cell. (C) 2015 AIP Publishing LLC.},
  language  = {en}
}