H. Stork

Bio: H. Stork is an academic researcher from Technische Universität Darmstadt. The author has contributed to research in topics: Relaxation (NMR) & Spin–lattice relaxation. The author has an hindex of 5, co-authored 11 publications receiving 70 citations.

Single-sided and semisingle-sided NMR sensors for highly diffusive samples: application to bottled beverages.

Abstract: Single-sided NMR sensors such as the NMR-MOUSE have been very successfully implemented for quality control applications in the rubber and polymer industries. More recently, single-sided NMR was also applied in characterization of the fat components in foods. Both industrial polymers and the fat components in food exhibit relatively low self-diffusion coefficients on the order of 5 × 10-11 m2/s or lower. The application of conventional single-sided NMR to highly mobile, watery phases in foods and beverages is hampered by the strong magnetic field gradient present in standard single-sided NMR devices. In this contribution, we present both a single-sided NMR sensor with a reduced magnetic field gradient and another (“semisingle-sided”) sensor design with an open sample bay using a single-sided RF coil. The latter design allows much better sensitivity without sacrificing the necessary open access needed for measurements on entire food packages such as bottles. As a first application, the sensors were used for...

Spatially resolved characterization of heavy ion irradiated crystals using static field gradient nuclear magnetic resonance

Abstract: Static magnetic field gradient NMR has been used for one-dimensional spatial 19F spin–lattice relaxation profile studies (resolution of the order of 10 µm) in a LiF crystal irradiated with U ions. Technical aspects of the use of large static magnetic field gradients are discussed as well as a special data acquisition mode allowing for effectively measuring spatially resolved spin–lattice relaxation rates as low as 10−3 s−1. In addition to the expected enhanced spin–lattice relaxation rate within the ion range, also an enhanced rate beyond the ion range has been found.

A Review of the Principles and Applications of the NMR Technique for Near-Surface Characterization

Abstract: This paper presents a comprehensive review of the recent advances in nuclear magnetic resonance (NMR) measurements for near-surface characterization using laboratory, borehole, and field technologies. During the last decade, NMR has become increasingly popular in near-surface geophysics due to substantial improvements in instrumentation, data processing, forward modeling, inversion, and measurement techniques. This paper starts with a description of the principal theory and applications of NMR. It presents a basic overview of near-surface NMR theory in terms of its physical background and discusses how NMR relaxation times are related to different relaxation processes occurring in porous media. As a next step, the recent and seminal near-surface NMR developments at each scale are discussed, and the limitations and challenges of the measurement are examined. To represent the growth of applications of near-surface NMR, case studies in a variety of different near-surface environments are reviewed and, as examples, two recent case studies are discussed in detail. Finally, this review demonstrates that there is a need for continued research in near-surface NMR and highlights necessary directions for future research. These recommendations include improving the signal-to-noise ratio, reducing the effective measurement dead time, and improving production rate of surface NMR (SNMR), reducing the minimum echo time of borehole NMR (BNMR) measurements, improving petrophysical NMR models of hydraulic conductivity and vadose zone parameters, and understanding the scale dependency of NMR properties.

Time domain NMR applied to food products

Abstract: Time-domain NMR is being used throughout all areas of food science and technology. A wide range of one- and two-dimensional relaxometric and diffusometric applications have been implemented on cost-effective, robust and easy-to-use benchtop NMR equipment. Time-domain NMR applications do not only cover research and development but also quality and process control in the food supply chain. Here the opportunity to further downsize and tailor equipment has allowed for “mobile” sensor applications as well as online quality inspection. The structural and compositional information produced by time-domain NMR experiments requires adequate data-analysis techniques. Here one can distinguish model-driven approaches for hypothesis testing, as well as explorative multi-variate approaches for hypothesis generation. Developments in hardware and software will further enhance measurement speed and reveal more detailed structural features in complex food systems.

Fluoride ion batteries – past, present, and future

Abstract: Fluoride-Ion Batteries (FIBs) have been recently proposed as a post-lithium-ion battery system. This review article presents recent progress of the synthesis and application aspects of the cathode, electrolyte, and anode materials for fluoride-ion batteries. In this respect, improvements in solid-state electrolytes for FIBs as well as liquid electrolytes will be discussed. Furthermore, the achievements regarding the development of cathode and anode materials will be considered. With the improvements made, the field is currently attracting a steady increase of interest, and we will discuss the potentials of this technology together with necessary future milestones to be achieved in order to develop FIBs for future energy storage.

Mixed Alkaline-Earth Effect in the Metastable Anion Conductor Ba1–xCaxF2 (0 ≤ x ≤ 1): Correlating Long-Range Ion Transport with Local Structures Revealed by Ultrafast 19F MAS NMR

Abstract: Fast ion conductors are urgently needed in many research areas of materials science. Advanced preparation strategies take advantage of an interplay of structural disorder, nanosize effects, and metastability. Getting access to detailed insights into the microstructure of such solids is crucial to identify the origins of fast ion conduction. High-resolution and high-sensitive spectroscopic techniques are well-suited to meet this challenge. Here, ion transport properties of a highly conducting, metastable fluoride with two isovalent cations were interrelated with the microscopic, atomic-scale structure probed by ultrafast 19F magic angle spinning (MAS) nuclear magnetic resonance (NMR). Nanocrystalline samples of Ba1–xCaxF2 (0 ≤ x ≤ 1) were prepared according to a mechanochemical route from BaF2 and CaF2. The resulting DC ion conductivity, when plotted as a function of x, passes through a well-developed maximum, which is located at xm = 0.5, while the associated activation energy Ea shows a minimum at xm. As...