Recent  

We present the ongoing work of a large, community initiative to establish standards for the processing of nonuniformly sampled NMR experiments. The NUScon software, contest, and archive of spectral evaluation data provide a comprehensive platform for addressing the most challenging questions related to NUS experiments. We will run annual contests and generate a database of results, which will empower us in guiding the NUS community towards a set of best practices.

We demonstrate the formation of spin noise echoes which occur after the application of opposite sign magnetic field gradients to an ensemble of spins. Exploiting this phenomenon, diffusion and spin relaxation parameters in concentrated samples can be determined from nuclear spin noise spectra acquired after tailored sequences of pulsed magnetic field gradients. These methods do not require any excitation from a radio frequency source.

To increase experimental efficiency, information can be encoded in parallel by taking advantage of highly resolved NMR spectra. Here we demonstrate parallel encoding of optimal diffusion parameters by selectively using a resonance for each molecule in the sample. This yields a factor of n decrease in experimental time since n experiments can be encoded into a single measurement. This principle can be extended to additional experimental parameters as a means to further improve measurement time.

The signals that are attainable in conventional NMR are tiny, and consequentially, NMR is often slow and insensitive. The intensity may be increased by hyperpolarization, provided that the spectral quality is essentially preserved. We have recently reported a potentially powerful hyperpolarization scheme, named bullet-DNP (dynamic nuclear polarization). Here, we report a 10-fold improvement in resolution for that method, which may enable new applications in metabolomics and drug discovery.

Fluorine NMR was used to study the interaction between a proline-rich peptide and a SH3 domain using 4S- and 4R-fluorinated prolines whose potential as NMR probes has not been exploited yet. We present a comprehensive study addressing several aspects to be considered when using these residues as NMR probes, including relaxation and dynamics. We show that their conformational bias may be used to modulate the kinetics of protein binding to proline-rich motifs.

We describe a suite of experiments that exploit field-dependent relaxation measurements of four-spin transitions in methyl groups to characterise chemical exchange processes and which can be used as an alternative or complement to CPMG relaxation dispersion measurements. We show that these four-spin transitions benefit from the methyl TROSY effect and so provide a unique combination of slow intrinsic relaxation and high sensitivity to chemical exchange.

The Biological Magnetic Resonance Data Bank (BMRB) has been used to identify overall trends, for example, the relationship between chemical shift and backbone conformation. The BMRB archive has grown so that statistical outliers are sufficiently numerous to afford insights into unusual or unique structural features in proteins. We analyze amide proton chemical shift outliers to gain insights into the occurrence of hydrogen bonds between an amide NH and the p-pi cloud of aromatic sidechains.

Quantum-rotor-induced polarization, also called the Haupt effect, is a hyperpolarization technique in NMR relying on the coupling of nuclear spin states to rotational quantum states. The classic molecule showing this effect is γ-picoline. One might assume that many other molecules carrying a methyl group might also show this effect. Here we explore, using a heuristic approach, other molecules which appear to be promising candidates.

Long-lived nuclear spin order helps extend the timescale of polarisation storage. This occurs as populations of nuclear spin singlet states feature slow decays compared to longitudinal magnetisation. The excitation of these symmetry-adapted states required spin choreographies that were often overshadowed in scholarly presentations by their applications. We recapitulate some of the milestones achieved in designing methods for long-lived spin order excitation and comment on future perspectives.

Diffusion-ordered spectroscopy (DOSY) seeks to distinguish between the NMR signals of chemical species of different sizes, using experimental measurements of spectra with different diffusion weighting. This paper examines how the signal-to-noise ratio of the experimental data influences the ability to distinguish small differences in diffusion coefficient between species.

There is growing interest in mapping exchange dynamics between Watson–Crick and Hoogsteen conformations across different DNA contexts. However, current methods are ill-suited for measurements at a large scale because they require isotopically enriched samples. We report that Hoogsteen dynamics can be measured on unlabeled samples using 1H CEST experiments, which have higher throughput and lower cost relative to conventional methods and also provide new insights into Hoogsteen dynamics.

Novel electron spin resonance (ESR) detectors based on voltage-controlled oscillators (VCOs) have been attracting attention, mainly due to the possibility of integrating the whole ESR spectrometer onto a single printed circuit board at relatively low cost while maintaining a performance comparable to commercial solutions. We present an experimental setup where the signal is detected as a change in VCO oscillation amplitude, along with in-depth theoretical analysis of the novel readout scheme.

The original theories of NMR relaxation by Felix Bloch are exposed and explicated, thereby connecting these marginalized but important scientific papers with the new modern approaches.

Electron paramagnetic resonance (EPR) spectroscopy is the method of choice to investigate and quantify paramagnetic species. We present the application of an unconventional EPR detection method, rapid-scan EPR, to enhance the sensitivity on an improved design of a miniaturized EPR spectrometer implemented on a silicon microchip. Due to its size, it may be integrated into complex and harsh sample environments, enabling in situ or operando EPR measurements that have previously been inaccessible.

A straightforward line shape analysis of the ¹³C NMR spectra of [2-¹³C]sodium acetate can be used to indirectly evaluate the ¹³H polarization of the CH₃ group and likely entire samples in the case of rapid and homogeneous ¹³H–¹H spin diffusion. The results are potentially advantageous for polarizers that lack ¹H radiofrequency hardware, measurements that are influenced by radiation damping or large background signals, or where acquisition of thermal equilibrium spectra is not feasible.

Kidney stones (KSs) are a major health problem in industrialized countries. The study of KSs is presently at the heart of a concerted multidisciplinary axis of research involving physicians, physical chemists and spectroscopists. In this contribution, an in-depth structural description of KSs is proposed by implementing a combination of multinuclear and multidimensional solid-state NMR methodology.