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  • Guthausen, Gisela  (6)
  • 1
    Online Resource
    Online Resource
    Investigation of Transverse Relaxation Rate Distribution via Magnetic Resonance Imaging: Impact of Electrode Formation
    Wiley ; 2021
    In:  Energy Technology Vol. 9, No. 6 ( 2021-06)
    Details
    In: Energy Technology, Wiley, Vol. 9, No. 6 ( 2021-06)
    Abstract: The impact of electrode formation is studied by the spatially and time‐resolved distribution of transverse relaxation. In situ 7 Li nuclear magnetic resonance experiments are performed on an experimental lithium‐ion battery cell to study the impact of electrode passivation via imaging and transverse relaxation in the interelectrode volume. The electrolyte in the battery, using technically relevant electrode material, i.e., graphite and lithium–nickel–cobalt–manganese–oxide, is studied by 2D magnetic resonance imaging. The electrolyte is 1 mol L −1 lithium hexafluorophosphate dissolved in a binary mixture of ethylene carbonate and dimethyl carbonate. 1D profiles are acquired and related to 7 Li concentration during passivation and during a constant current/constant voltage cycle. The transverse relaxation rate R 2 ( z , t ) measured by multiecho profiles revealed changes within the electrolyte volume. The ongoing process changes the relaxation distribution. Indications for a defective electrode passivation are deduced from the data. During one charging cycle with constant current/constant voltage, the lithium concentration is measured spatially resolved, and the data are modeled by the Nernst–Planck equation.
    Type of Medium: Online Resource
    ISSN: 2194-4288 , 2194-4296
    URL: Issue
    URL: Article
    DOI: 10.1002/ente.v9.6
    DOI: 10.1002/ente.202000579
    Language: English
    Publisher: Wiley
    Publication Date: 2021
    detail.hit.zdb_id: 2700412-0
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  • 2
    Online Resource
    Online Resource
    Combined nuclear magnetic resonance methods in quality control of lubricants in green energy production
    Wiley ; 2023
    In:  Magnetic Resonance in Chemistry
    Details
    In: Magnetic Resonance in Chemistry, Wiley
    Abstract: NMR methods were applied for lubricant analysis. Different factors influence the real aging of lubricants on diverse length scales and are captured by NMR. Chemical conversion of additives is addressed by NMR spectroscopy. High‐field NMR experiments allow the identification and quantification of chemical components and are transferred to benchtop devices. Molecular dynamics and contaminations like fuel or abrasion are addressed via NMR relaxation and diffusion. Quality parameters were extracted via suitable data analysis of NMR raw data, which allow the detection of aging and indicate changes in the oil composition. At the same time, the methodology is optimized to the conditions in quality control. The feasibility is shown the example of a series of lubricants from applications in regenerative energy production, namely, wind turbine oils and biogas motor oils.
    Type of Medium: Online Resource
    ISSN: 0749-1581 , 1097-458X
    URL: Article
    DOI: 10.1002/mrc.5339
    RVK:
    VA 5830
    Language: English
    Publisher: Wiley
    Publication Date: 2023
    detail.hit.zdb_id: 1475029-6
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  • 3
    Online Resource
    Online Resource
    Dedicated NMR sensor to analyze relaxation and diffusion in liquids and its application to characterize lubricants
    Wiley ; 2021
    In:  Magnetic Resonance in Chemistry Vol. 59, No. 8 ( 2021-08), p. 825-834
    Details
    In: Magnetic Resonance in Chemistry, Wiley, Vol. 59, No. 8 ( 2021-08), p. 825-834
    Abstract: A dedicated nuclear magnetic resonance (NMR) sensor was designed for the analysis of liquids. The magnets are arranged in a V shape, creating a spatially dependent magnetic field in the gap. Measurements of samples with diverse diameters are possible underdefined magnetic field gradients at a given position. The magnet thus combines properties of single sided NMR with high static magnetic field gradients and classical time domain (TD) devices with lower to almost zero gradients. The sensor can easily be adapted to the requirements of the considered investigation; probes can be customized. On the example of lubricants and their aging, the added value and applicability of this sensor in quality control are highlighted in this publication. Relaxation and diffusion were measured by Carr–Purcell–Meiboom–Gill (CPMG) while varying the echo time τ e and quantified via numerical modeling. Especially, relaxation shows a high sensitivity towards aging of lubricants such as particulate abrasion and changes in molecular dynamics induced, for example, by additive depletion. The applicability of this NMR sensor in quality control is demonstrated on the example of engine and transmission oils as well as of lubrication greases.
    Type of Medium: Online Resource
    ISSN: 0749-1581 , 1097-458X
    URL: Issue
    URL: Article
    DOI: 10.1002/mrc.v59.8
    DOI: 10.1002/mrc.5155
    RVK:
    VA 5830
    Language: English
    Publisher: Wiley
    Publication Date: 2021
    detail.hit.zdb_id: 1475029-6
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  • 4
    Online Resource
    Online Resource
    Low‐field NMR for quality control on oils
    Wiley ; 2019
    In:  Magnetic Resonance in Chemistry Vol. 57, No. 10 ( 2019-10), p. 777-793
    Details
    In: Magnetic Resonance in Chemistry, Wiley, Vol. 57, No. 10 ( 2019-10), p. 777-793
    Abstract: Oil is a prominent, but multifaceted material class with a wide variety of applications. Technical oils, crude oils as well as edibles are main subclasses. In this review, the question is addressed how low‐field NMR can contribute in oil characterization as an analytical tool, mainly with respect to quality control. Prerequisite in the development of a quality control application, however, is a detailed understanding of the oils and of the measurement. Low‐field NMR is known as a rich methodical toolbox that was and is explored and further developed to address questions about oils, their quality, and usability as raw materials, during production and formulation as well as in use.
    Type of Medium: Online Resource
    ISSN: 0749-1581 , 1097-458X
    URL: Issue
    URL: Article
    DOI: 10.1002/mrc.v57.10
    DOI: 10.1002/mrc.4856
    RVK:
    VA 5830
    Language: English
    Publisher: Wiley
    Publication Date: 2019
    detail.hit.zdb_id: 1475029-6
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  • 5
    Online Resource
    Online Resource
    Inline NMR via a Dedicated V-Shaped Sensor
    MDPI AG ; 2023
    In:  Sensors Vol. 23, No. 5 ( 2023-02-21), p. 2388-
    Details
    In: Sensors, MDPI AG, Vol. 23, No. 5 ( 2023-02-21), p. 2388-
    Abstract: Process monitoring and control require dedicated and reliable measures which reflect the status of the process under investigation. Although nuclear magnetic resonance is known to be a versatile analytical technique, it is only seldomly found in process monitoring. Single-sided nuclear magnetic resonance is one well known approach for being applied in process monitoring. The dedicated V-sensor is a recent approach that allows the inline investigation of materials in a pipe non-destructively and non-invasively. An open geometry of the radiofrequency unit is realized using a tailored coil, enabling the sensor to be applied for manifold mobile applications in in-line process monitoring. Stationary liquids were measured, and their properties were integrally quantified as the basis for successful process monitoring. The sensor, in its inline version, is presented along with its characteristics. An exemplary field of application is battery production in terms of anode slurries; thus, the first results on graphite slurries will demonstrate the added value of the sensor in process monitoring.
    Type of Medium: Online Resource
    ISSN: 1424-8220
    URL: Article
    DOI: 10.3390/s23052388
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2052857-7
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  • 6
    Online Resource
    Online Resource
    Nuclear magnetic resonance/magnetic resonance imaging on lubricating greases: Observation of bleeding and aging
    Wiley ; 2022
    In:  Magnetic Resonance in Chemistry Vol. 60, No. 4 ( 2022-04), p. 452-462
    Details
    In: Magnetic Resonance in Chemistry, Wiley, Vol. 60, No. 4 ( 2022-04), p. 452-462
    Abstract: Lubricating greases were investigated by nuclear magnetic resonance/magnetic resonance imaging (NMR/MRI) to get insight into their structure and into their response to mechanical forces, which is related to bleeding and aging. The investigated greases are based on metallic soaps of fatty acids and oils, whereby LiOH is often used. These organic soaps act as thickeners and provide a network in which oils and their additives are embedded. Lubricating greases can thus be considered as a class of substances similar to oleogels or even hydrogels. Questions arise about translational mobility of guest molecules, mainly base oil, in these networks. Molecular structuring and interactions within the network of thickeners are of interest as they are related to macroscopic stability. Apart from NMR spectroscopy ( 1 H‐, 7 Li‐ and 31 P‐NMR), spectrally resolved relaxation and diffusion measurements are used for characterization. In addition, magic angle spinning (MAS)‐NMR was combined with 1 H‐MRI to investigate the impact of mechanical stress and swelling of lubricating greases.
    Type of Medium: Online Resource
    ISSN: 0749-1581 , 1097-458X
    URL: Issue
    URL: Article
    DOI: 10.1002/mrc.v60.4
    DOI: 10.1002/mrc.5243
    RVK:
    VA 5830
    Language: English
    Publisher: Wiley
    Publication Date: 2022
    detail.hit.zdb_id: 1475029-6
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