The random motion (the diffusion) of guest molecules in nanoporous host materials is key to their manifold technological applications and, simultaneously, a ubiquitous phenomenon in nature quite in general. Based on a specification of the different conditions under which molecular diffusion in nanoporous materials may occur and of the thus resulting relevant parameters, a survey of the various ways of the measurement of the determining parameters is given. Starting with a condensed introduction to the respective measuring principles, the survey notably includes a summary of the various parameters accessible by each individual technique, jointly with an overview of their strengths and weaknesses as well as of the respective ranges of observation. The presentation is complemented by basic relations of diffusion theory and molecular modeling in nanoporous materials, illustrating their significance for enhancing the informative value of each measuring technique and the added value attainable by their combination. By providing guidelines for the measurement and reporting of diffusion properties of chemical compounds in nanopores, the document aims to contribute to the clarification and standardization of the presentation, nomenclature, and methodology associated with the documentation of diffusion phenomena in nanoporous materials serving for catalytic, mass separation, and other relevant purposes.

Proton NMR is one of the key analytical technologies in the field of metabolomics, as it allows one to combine untargeted, targeted, and quantitative metabolite measurements. One of NMR's greatest strengths is the ability to unambiguously identify compounds when present at mg/L concentrations, without the use of expensive or hard-to-source reference compounds. Furthermore, identification can be performed non-destructively on complex samples without the need for further sample preparation and isolation.Here, we describe a series of NMR experiments and data processing techniques to unambiguously identify the metabolite pyroglutamic acid (pGlu) in wine samples, without prior enrichment or separation from matrix compounds and other metabolites typically present in wine. Subsequently, the concentration of pGlu in 100 Australian wines was determined using standard NMR protocols. Statistical analysis demonstrated that occurrence of pGlu is associated with glutamic acid, is linked to vintage conditions and accumulated heat over the growing season, and is negatively associated with rainfall during the growing season. Overall, the results establish the presence and typical concentrations of the amino acid metabolite pGlu in Australian wine.

NMR diffusion measurements have the promise to provide deep insight into chemical reactions and processes including self-assembly, reaction kinetics, crystallization, and binding. However, when the chemical system alters on the timescale of the diffusion measurement, great care must be taken in both the performance and interpretation of the data. This paper considers the various NMR diffusion timescales, some of the problems that arise with time-variant systems, and various ways that the problems can be removed or at least reduced.

Dihydrogen phosphate anions are found to spontaneously associate into anti-electrostatic oligomers via hydrogen bonding interactions at millimolar concentrations in DMSO. Diffusion NMR measurements supported formation of these oligomers, which can be bound by photoswitchable anion receptors to form large bridged assemblies of approximately three times the volume of the unbound receptor. Photoisomerization of the oligomer-bound receptor causes a decrease in diffusion coefficient of up to 16%, corresponding to a 70% increase in effective volume. This new approach to external control of diffusion opens prospects in controlling molecular transport.

High-value utilization of lignocellulose and its components is generally constrained by the pretreatment efficiency and the structural robustness of fractionated components. Harsh pretreatment conditions can promote pretreatment efficiency but also cause serious condensation of lignin structure, thus inhibiting the depolymerization of lignin into valuable chemicals. Herein, we designed a novel deep eutectic solvent (DES) composed of pyridine hydrochloride, ethylene glycol, and AlCl3 for the pretreatment of lignocellulose. In the developed DES, the lignocellulose could be efficiently fractionated into the natural lignin derivatives with satisfactory hydrogenolysis reactivity and the carbohydrate fraction with high enzymatic digestibility owing to the synthesized DES having adjustable hydrogen-bond acidity, high affinity for lignin, and good protection role on lignin structure. After being pretreated under a mild fractionation condition (70 degrees C, 6 h), a promising delignification ratio of 70.4 % was obtained for poplar, and the extracted lignin exhibited native substructure with well-preserved beta-O-4 linkages (42.1 per 100 aromatic units), abundant hydroxyl groups content (4.97 mmol/g), and high molecular weight (5643 g/mol). These structural features contributed to the conversion of the obtained lignin into aromatic monomers with a high yield (27.4 %). Besides, the pretreated residue could be efficiently converted into glucose with a yield of 88.2 % due to the abundant hydroxyl groups of lignin in the cellulose-rich residues. Remarkably, comprehensive studies of lignin structural evolution during pretreatment revealed that the structure-controllable lignin could be effectively isolated by modulating the hydrogen-bond acidity of DESs. This work proposed a mild and efficient lignin-first biorefinery approach that was conducive to the integrated valorization of lignocellulose.

Progress in the development of manganese oxide nanoparticles (MONPs) has offered an alternative to the current Gd-based T1 magnetic resonance image (MRI) contrast agents for early-stage diagnosis of life-threatening diseases. MONPs also possess unique self-degradation characteristics, making them suitable for the therapeutic delivery of drugs and genes. Advances in the NP synthesis and characterisation, especially fundamental insights into the thermodynamically and kinetically controlled growth of NP and rich surface chemistry offering conjugation of biomolecules and polymers to its surface, have enabled the reproducible production of multifunctional targeted MONPs in various sizes and shapes. The integration of diagnosis and therapeutic capabilities within a single entity, so-called "nanotheranostics", has offered new hope for using them for simultaneous real-time monitoring of disease progression in response to the treatment, thus evaluating the efficacy of therapeutic treatment. In this review, we highlight the recent advancements in the synthesis of MONPs and functionalisation strategies used to realise their theranostic potential. We discuss the basic physics of MR imaging and factors influencing the contrast enhancement mechanism of MONPs and review the use of multifunctional MONPs for dual and multimodal imaging and therapeutic delivery applications. This review also discusses how the biological properties of MONPs can influence their performance in a biological environment, including induced toxicity, which should be taken into consideration for designing next-generation engineered precision MONPs for disease diagnosis and treatment. Finally, we also provide a forward-looking perspective to accelerate the translation of MONPs into the clinical setting.

In this study, droplet size distributions (DSDs) of oil-in-water Pickering emulsions stabilized by cellulose nanofibers (CNFs) estimated from NMR diffusion measurements in conjunction with cogent mathematical modelling based on the Gaussian phase distribution (GPD) approximation for diffusion in a sphere. The effects of oil types and Pickering stabilizer loadings on DSDs were investigated by using different n-alkanes (octane to hexadecane) and CNF concentrations (0.5 to 1%). The NMR diffusion data of the dispersed oil were well-described by the GPD model with a monomodal log-normal distribution. Pickering emulsions composed of higher n-alkane carbon number and/or CNF concentration were found to have smaller median radii, RMedian, and these RMedian estimates were in good agreement with laser scattering data. The volume-based RMedian against the CNF concentrations or the number of hydrocarbon n-alkanes exhibited an approximate exponential relationship.

Gas exchange mechanisms play crucial roles in maintaining fruit post-harvest quality in perishable fruit such as strawberry (Fragaria×ananassa Duch.) and blueberry (Vaccinium corymbosum L.). The internal oxygen concentration ([O2 ]) of strawberry and blueberry were measured using Clark-type oxygen sensing electrodes. The volume of intercellular voids in strawberry was obtained by micro-computed tomography (micro-CT). In both berries, internal [O2 ] was consistent and relatively high across measured tissues. The overall [O2 ] was well above the Michaelis constant (K m ) for cytochrome c oxidase in both fruit and different from previously examined grape (Vitis vinifera L.) berry mesocarp with near zero minimum [O2 ]. In strawberry and blueberry, cell vitality was also maintained at full maturity in the mesocarp. Higher storage temperature (i.e. 20 vs 4°C) reduced internal [O2 ] of strawberry. Pedicel detachment in blueberry was associated with greater fruit dehydration and lower internal [O2 ] after short-term storage of 12h. The results suggest that the intercellular voids of the fruit's mesocarp provide an efficient gas exchange route for maintaining high fruit internal [O2 ] post-harvest.

Freezing is likely the severest environmental stress for plants. Plant distribution and agricultural production are often limited by the minimum winter temperatures. Temperate woody perennials are exposed to recurrent freeze-thaw cycles during winter. How do their organs/tissues cope with freezing of tissue water? Cold hardy plants have evolved various strategies (freezing behaviours) to avoid lethal intracellular freezing. These freezing behaviours are tissue and species specific and require various mechanisms to regulate the behaviours (phase and movement) of tissue water. Yet, their diversity, dynamics and mechanisms remain poorly understood as freezing events in complex thick plant organs are not visible and difficult to analyse. Magnetic resonance provides a suite of tools, including magnetic resonance imaging, relaxation and diffusometry, for studying the underlying processes in exquisite detail both at the plant organ/tissue level and also for understanding the molecular level interactions involved in the ice nucleation process. Importantly, magnetic resonance can do this non-invasively which is especially important when studying such delicate thermodynamic systems involving supercooled water. This chapter gives an overview of the relevant physiological backgrounds and water physical properties including the molecular dynamics of water (i.e., self-diffusion and reorientational motion) and relationships to plant structure. An overview of the salient points of the magnetic resonance ‘toolbox’ is given to enable non-magnetic resonance experts to understand the literature. Finally, numerous applications of the magnetic resonance techniques to freezing and injury in plants are surveyed and consideration given to possible future studies, such as imaging localisation of particular functional compounds and visualising adaptive strategies to arid environments.

Magnetic resonance imaging (MRI) relaxometry and diffusion methods were used to highlight the instability mechanisms of oil-in-water Pickering emulsions stabilized by cellulose nanofibers (CNFs). Four different Pickering emulsions using different oils (n-dodecane and olive oil) and concentrations of CNFs (0.5 and 1.0 wt %) were systematically investigated over a period of one month after emulsification. The separation into a free oil, emulsion layer, and serum layer and the distribution of flocculated/coalesced oil droplets in several hundred micrometers were captured in MR images using fast low-angle shot (FLASH) and rapid acquisition with relaxation enhancement (RARE) sequences. The components of the Pickering emulsions (e.g., free oil, emulsion layer, oil droplets, and serum layer) were observable by different voxelwise relaxation times and apparent diffusion coefficients (ADCs) and reconstructing in the apparent T1, T2, and ADC maps. The mean T1, T2, and ADC of the free oil and serum layer corresponded well with MRI results for pure oils and water, respectively. Comparing the relaxation properties and translational diffusion coefficients of pure dodecane and olive oil obtained from NMR and MRI resulted in similar T1 and ADC but significantly different T2 depending on the sequence used. The diffusion coefficients of olive oil measured by NMR were much slower than dodecane. The ADC of the emulsion layer for dodecane emulsions did not correlate with the viscosity of the emulsions as the CNF concentration increased, suggesting the effects of restricted diffusion of oil/water molecules due to droplet packing.

Background In recent years, the focus of traditional Chinese medicine (TCM) research has gradually shifted from pure chemical research to looking at the combination of chemistry with the life sciences. However, due to the complexity of the chemical composition of Chinese medicinal plants, understanding material structure through in vivo and in vitro studies is a bottleneck in biological analysis. Nuclear magnetic resonance (NMR) spectroscopy has numerous unique advantages over other analytical techniques, and has developed into a crucial tool in Chinese medicine research. This review aims to analyze and summarize the application of NMR under the multiple fields of TCM. Methods The online databases PubMed, Web of Science, Embase, Cochrane Library, and CNKI were using the search terms “Nuclear magnetic resonance spectrometry,” “NMR,”“Chinese medicine,” “TCM,” “Herbal medicine,” were from January 1, 2010 to June 1, 2023 Results The research scopes were 375 after being selected. The latest applications of NMR to TCM including its application to metabolomics, structural identification and efficacy exploration, and authentication and quality control. There were 116 articles on metabolism, 196 articles on compound structure identification and 63 articles on quality control. The metabolomic study of NMR is in line with the multicomponent, multitarget, and overall comprehensive effect of TCM. The structural identification of the chemical components of TCM is more helpful for the discovery of other biologically active substances with high efficacy and few side effects. NMR provides support in quality control and planting site selection of TCM. Conclusion NMR has become an essential tool and makes great contributions to the field of TCM research, the innovation in the application of NMR technology will aid with the research on the material basis of TCM.

The self-diffusion coefficients of D2O (i.e., heavy water or 2H2O) in eight n-alkanes at 298 K were investigated using 2H NMR diffusometry. D tended to decrease in the n-alkanes with increasing carbon number and be inversely proportional to the n-alkane viscosity to a fractional power. The hydrodynamic radius of D2O in the n- alkanes, calculated from Stokes-Einstein-Sutherland equation with stick boundary conditions, decreased with increasing n-alkane size and was smaller in the n-alkanes than in the bulk phase due to the absence of hydrogen bonds. This study provides fundamental data on the diffusion properties of water molecules dissolved in n-al-kanes with applications to, for instance, molecular dynamics simulations or interpretation of Ostwald ripening.

To explore diversity in cold hardiness mechanisms, high resolution magnetic resonance imaging (MRI) was used to visualise freezing behaviours in wintering Daphne kamtschatica var. jezoensis flower buds, which have naked florets and no bud scales. MRI images showed that anthers remained stably supercooled to the range from -14 to -21°C or lower while most other tissues froze by -7°C. Freezing of some anthers detected in MRI images between -14 and -21°C corresponded with numerous low temperature exotherms and also with the 'all-or-nothing' type of anther injuries. In ovules/pistils, only embryo sacs remained supercooled at -7°C or lower, but slowly dehydrated during further cooling. Cryomicroscopic observation revealed ice formation in the cavities of calyx tubes and pistils but detected no ice in embryo sacs or in anthers. The distribution of ice nucleation activity in floral tissues corroborated the tissue freezing behaviours. Filaments likely work as the ice blocking barrier that prevents ice intrusion from extracellularly frozen calyx tubes to connecting unfrozen anthers. Unique freezing behaviours were demonstrated in Daphne flower buds: preferential freezing avoidance in male and female gametophytes and their surrounding tissues (by stable supercooling in anthers and by supercooling with slow dehydration in embryo sacs) while the remaining tissues tolerate extracellular freezing.

This proof-of-concept study looked at the feasibility of using a thiol–water proton exchange (i.e., CEST) MRI contrast to detect in vivo hepatic N-acetylcysteine (NAC) uptake. The feasibility of detecting NAC-induced glutathione (GSH) biosynthesis using CEST MRI was also investigated. The detectability of the GSH amide and NAC thiol CEST effect at B0 = 7 T was determined in phantom experiments and simulations. C57BL/6 mice were injected intravenously (IV) with 50 g L−1 NAC in PBS (pH 7) during MRI acquisition. The dynamic magnetisation transfer ratio (MTR) and partial Z-spectral data were generated from the acquisition of measurements of the upfield NAC thiol and downfield GSH amide CEST effects in the liver. The 1H-NMR spectroscopy on aqueous mouse liver extracts, post-NAC-injection, was performed to verify hepatic NAC uptake. The dynamic MTR and partial Z-spectral data revealed a significant attenuation of the mouse liver MR signal when a saturation pulse was applied at −2.7 ppm (i.e., NAC thiol proton resonance) after the IV injection of the NAC solution. The 1H-NMR data revealed the presence of hepatic NAC, which coincided strongly with the increased upfield MTR in the dynamic CEST data, providing strong evidence that hepatic NAC uptake was detected. However, this MTR enhancement was attributed to a combination of NAC thiol CEST and some other upfield MT-generating mechanism(s) to be identified in future studies. The detection of hepatic GSH via its amide CEST MRI contrast was inconclusive based on the current results.

Intra-diffusion coefficients (DSi) have been measured for the ionic liquid constituent ions and aluminium-containing species in aluminium chloride (AlCl3) solutions in the ionic liquids 1-(2-dimethyl-aminoethyl)-dimethylethylammonium bis(trifluoromethylsulfonyl)amide ([C2TMEDA][Tf2N]) and N-butyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide ([C4mpyr][Tf2N]), to investigate whether spectroscopically detected interactions between the ions and AlCl3 affect these properties. Such electrolyte solutions are of interest for the electrowinning of aluminium. The temperature, composition and molar volume dependences are investigated. Apparent (Vϕ,1) and partial molar (V1) volumes for AlCl3 have been calculated from solution densities. For [C2TMEDA][Tf2N] solutions, Vϕ,1 increases with increasing solute concentration; for [C4mpyr][Tf2N] solutions, it decreases. In pure [C2TMEDA][Tf2N], the cation diffuses more quickly than the anion, but this changes as the AlCl3 concentration increases. In the [C4mpyr][Tf2N] solutions, the intra-diffusion coefficient ratio remains equal to that for the pure ionic liquid and the aluminium species diffuses at approximately the same rate as the anion at each composition. The intra-diffusion coefficients can be fitted to the Ertl-Dullien free volume power law by superposing the iso-concentration curves with concentration dependent, but temperature independent, molar volume offsets. This suggests that they are primarily dependent on the molar volume and secondarily on a colligative thermodynamic factor due to dilution by AlCl3. AlCl3 complexation by [Tf2N]- and [C2TMEDA]+, confirmed by 27Al, 15N and 19F NMR spectroscopy, seems to play a minor role. Our results indicate that the application of free volume theories might be fruitful in the study of the transport properties of ionic liquid solutions and mixtures.

Gas exchange mechanisms play crucial roles in maintaining fruit post-harvest quality in perishable fruit such as strawberry (Fragaria × ananassa Duch.) and blueberry (Vaccinium corymbosum L.). The internal oxygen concentration ([O2]) of strawberry and blueberry were measured using Clark-type oxygen sensing electrodes. The volume of intercellular voids in strawberry was obtained by micro-computed tomography (micro-CT). In both berries, internal [O2] was consistent and relatively high across measured tissues. The overall [O2] was well above the Michaelis constant (Km) for cytochrome c oxidase in both fruit and different from previously examined grape (Vitis vinifera L.) berry mesocarp with near zero minimum [O2]. In strawberry and blueberry, cell vitality was also maintained at full maturity in the mesocarp. Higher storage temperature (i.e. 20 vs 4°C) reduced internal [O2] of strawberry. Pedicel detachment in blueberry was associated with greater fruit dehydration and lower internal [O2] after short-term storage of 12 h. The results suggest that the intercellular voids of the fruit’s mesocarp provide an efficient gas exchange route for maintaining high fruit internal [O2] post-harvest.

Online, high-throughput molecular weight analysis of polymerizations is rare, with most studies relying on tedious sampling techniques and batchwise postanalysis. The ability to track both monomer conversion and molecular weight evolution in real time could underpin precision polymer development and facilitate study of rapid polymerization reactions. Here, we use a single time-resolved diffusion nuclear magnetic resonance (NMR) experiment to simultaneously study the kinetics and molecular weight evolution during a photopolymerization, with in situ irradiation inside the NMR instrument. As a model system, we used a photoinduced electron transfer reversible addition-fragmentation chain transfer (PET-RAFT) polymerization. The data allow diffusion coefficients and intensities to be calculated every 14 s from which the polymer size and monomer conversion can be extracted. Key to this approach is (1) the use of shuffled gradient amplitudes in the diffusion NMR experiment to access reactions of any rate, (2) the addition of a relaxation agent to increase achievable time resolution and, (3) a sliding correction that accounts for viscosity changes during polymerization. Diffusion NMR offers a uniquely simple, translatable handle for online monitoring of polymerization reactions.