Magnetic resonance (Gottingen, Germany)最新文献

Conference travel contributes to the climate footprint of academic research. Here, we provide a quantitative estimate of the carbon emissions associated with conference attendance by analyzing travel data from participants of 10 international conferences in the field of magnetic resonance, namely EUROMAR, ENC and ICMRBS. We find that attending a EUROMAR conference produces, on average, more than 1 t ${\mathrm{CO}}_{2\mathrm{eq}.}$ . For the analyzed conferences outside Europe, the corresponding value is about 2-3 times higher, on average, with intercontinental trips amounting to up to 5 t. We compare these conference-related emissions to other activities associated with research and show that conference travel is a substantial portion of the total climate footprint of a researcher in magnetic resonance. We explore several strategies to reduce these emissions, including the impact of selecting conference venues more strategically and the possibility of decentralized conferences. Through a detailed comparison of train versus air travel - accounting for both direct and infrastructure-related emissions - we demonstrate that train travel offers considerable carbon savings. These data may provide a basis for strategic choices of future conferences in the field and for individuals deciding on their conference attendance.

Combining high-resolution high-field nuclear magnetic resonance (NMR) with an evolution of spin systems at a low magnetic field offers many opportunities for the investigation of molecular motions and hyperpolarization and the exploration of field-dependent spin dynamics. Fast and reproducible transfer between high and low fields is required to minimize polarization losses due to longitudinal relaxation. Here, we introduce a new design of a sample shuttle that achieves remarkably high speeds ( $v_{\max }$ $\sim$ 27 m s^-1). This hybrid pneumatic-mechanical apparatus is compatible with conventional probes at the high-field center. We show applications in water relaxometry in solutions of paramagnetic ions, high-resolution proton relaxometry of a small molecule, and sample shuttling of a solution of a 42 kDa protein. Importantly, this fast sample shuttle (FSS) system is narrow, with a diameter of $d$ $=$ 6 mm for the sample shuttle container based on a standard 5 mm outer diameter glass tube, which should allow near access to the sample for magnetic manipulation at a low field.

Additive manufacturing has enabled rapid prototyping of components with minimum investment in specific fabrication infrastructure. These tools allow for a fast iteration from design to functional prototypes within days or even hours. Such prototyping technologies exist in many fields, including three-dimensional mechanical components and printed electric circuit boards (PCBs) for electrical connectivity, to mention two. In the case of nuclear magnetic resonance (NMR) spectroscopy, one needs the combination of both fields; we need to fabricate three-dimensional electrically conductive tracks as coils that are wrapped around a sample container. Fabricating such structures is difficult (e.g., six-axis micro-milling) or simply not possible with conventional methods. In this paper, we modified an additive manufacturing method that is based on the extrusion of conductive ink to fast-prototype solenoidal coil designs for NMR. These NMR coils need to be as close to the sample as possible and, by their shape, have specific inductive values. The performance of the designs was first investigated using electromagnetic field simulations and circuit simulations. The coil found to have optimal parameters for NMR was fabricated by extrusion printing, and its performance was tested in a 1.05 $T$ imaging magnet. The objective is to demonstrate reproducible rapid prototyping of complicated designs with high precision that, as a side effect, hardly produces material waste during production.

The implementation of parallel nuclear magnetic resonance detection aims to enhance measurement throughput in support of high-throughput-screening applications, including, for example, drug discovery. In support of modern pulse sequences and solvent suppression methods, each detection site must have independent pulsed field gradient capabilities. Hereby, a challenge is introduced in which the local gradients applied in parallel detectors introduce field spillover into adjacent channels, leading to spin dephasing and, hence, to signal suppression. This study proposes a compensation scheme employing optimized pulses to achieve coherence locking during gradient pulse periods. The design of coherence-locking pulses utilizes optimal control to address gradient-induced field inhomogeneity. These pulses are applied in a pulsed-gradient spin echo (PGSE) experiment and a parallel heteronuclear single quantum coherence (HSQC) experiment, demonstrating their effectiveness in protecting the desired coherences from gradient field spillover. This compensation scheme presents a valuable solution for magnetic resonance probes equipped with parallel and independently switchable gradient coils.

Nuclear quadrupole resonance (NQR), a technique related to nuclear magnetic resonance, is extremely sensitive to local crystal composition and structure. Unfortunately, in disordered materials, this sensitivity also leads to very large linewidths, presenting a technical challenge and requiring a serious time investment to get a full spectrum. Here, we describe our newly developed, automated NQR set-up to acquire high-quality wide-line spectra. Using this set-up, we carried out ¹²⁷I NQR on three mixed-cation lead-halide perovskites (LHPs) of the form MA _x FA_1-x PbI₃ (where MA denotes methylammonium; FA denotes formamidinium; and $x=$ 0.25, 0.50 and 0.75) at various temperatures. We achieve a signal-to-noise ratio of up to $\sim 400$ for lineshapes with a full width at half maximum of $\sim 2.5\mathrm{MHz}$ acquired with a spectral width of 20 MHz in the course of 2-3 d. The spectra, which at least partially exhibit features encoding structural information, are interpreted using a statistical model. This model finds a degree of MA-MA and FA-FA clustering ( $0.2\le S\le 0.35$ ). This proof-of-principle for both the wide-line NQR set-up and the statistical model widens the applicability of an underutilised avenue of non-invasive structural research.

Standard solution NMR measurements use 5 mm outer diameter (OD) sample tubes that require ca. 0.5 mL of solvent to minimize "end effects" on magnetic field homogeneity in the active volume of the sample. Shigemi cells reduce the solvent requirement to ca. 0.29 mL. At high ionic strength or at ultrahigh magnetic fields, smaller OD samples are needed to study samples in conductive, radiofrequency-absorbing solvents such as water. We demonstrate an effective and inexpensive alternative for reducing the active sample volume to 0.13 mL by 3D printing ellipsoidal shaped cells that are inserted into 5 mm OD NMR tubes. Static magnetic susceptibility, $\chi$ , of printer resin was measured using a simple slice-selection pulse sequence. We found that the $\chi$ of water increases linearly with NaCl concentration from $-9.05$ to $-8.65$ ppm for 0 to 2 M NaCl. The $\chi$ of D₂O was measured to be $-9.01$ ppm. The susceptibility difference between the resin ( $\chi =-9.40$ ppm) and water can be minimized by paramagnetic doping of the resin. Such doping was found to be unnecessary for obtaining high-quality protein NMR spectra when using ellipsoidal-shaped cells that are insensitive to susceptibility mismatching. The microcells offer outstanding radiofrequency (RF) and good $B_o$ homogeneities. Integrated 600 MHz heteronuclear single quantum coherence (HSQC) signal intensities for the microcell sample in phosphate-buffered saline (PBS) buffer were $6.5\pm 4$ % lower than for 0.5 mL of the same protein solution in a regular 5 mm sample tube. The cell is demonstrated for N-acetylated $\alpha$ -synuclein in PBS buffer and for observing tetramerization of melittin at 2 M NaCl.

Enhanced transverse relaxation near rotary resonance conditions is a well-documented effect for anisotropic solid samples undergoing magic-angle spinning (MAS). We report transverse signal decay associated with rotary resonance conditions for rotating liquids, a surprising observation, since first-order anisotropic interactions are averaged at a much faster timescale compared with the spinning frequency. We report measurements of ${}^{13}C$ and ${}^{1}H$ signal intensities under spin lock for spinning samples of polybutadiene rubber, polyethylene glycol solution, and 99.96 % $D_{2}O$ . A drastic reduction in spin-lock signal intensities is observed when the spin-lock frequency matches 1 or 2 times the MAS rate. In addition, oscillations of the signal are observed, consistent with a coherent origin of the effect, a pseudo rotary resonance relaxation dispersion (pseudo-RRD). Through simulations, we qualitatively describe the appearance of pseudo-RRD, which can be explained by time dependence caused by sample rotation and an inhomogeneous field, the origin of which is an instrumental imperfection. Consideration of this effect is important for MAS experiments based on rotary resonance conditions and motivates the design of new MAS coils with improved radio frequency (RF)-field homogeneity.

Usually, conventional electron paramagnetic resonance (EPR) spectroscopy and imaging employ a microwave cavity operating at X-band, i.e.,  with an excitation frequency of around 9.6 GHz, and this remains the most popular mode for the magnetic characterization of lithium batteries to date. Here, we provide the first low-frequency EPR investigations with respect to monitoring the metallic lithium structures in solid-state pouch cell batteries. We show that L-band, i.e., a microwave frequency of around 1.01 GHz, is an invaluable method to probe the electrode components directly through a standard pouch cell using aluminum-laminated film for packaging without opening the battery. These results offer a new approach for monitoring the nucleation of micrometric and submicrometric lithium particles, such as dendritic lithium structures, and is an important step in the development of reliable solid-state batteries.