Nondestructive Nuclear Magnetic Resonance Research Articles

Operando NMR Characterization of Cycled and Calendar Aged Si Anodes

Replacing graphite anodes with Si anodes can greatly increase the capacity of current Li-ion batteries. Detailed characterization of Si lithiation reactions, solid electrolyte interphase (SEI) formation, and reversibility are therefore active areas of research. Solid-state nuclear magnetic resonance (NMR) spectroscopy is useful for characterizing different local environments within Si anodes as well as differentiating surface and bulk environments. Furthermore, non-invasive and non-destructive NMR methods can reveal metastable LixSi phases or SEI species forming on (dis)charge that may be too reactive to detect via ex situ methods. Here, we use an in situ and in operando NMR methodology to characterize full pouch cells comprising of Si anodes and NMC cathodes. We can observe changes in the relative amounts of Li in different environments within the same Si anode before/during/after charge & discharge and with various amounts of cycling or calendar aging using in situ 7Li NMR. The pouch cells used in our in situ NMR study are comparable to pouch cells made using mid- to large-scale fabrication methods as opposed to laboratory scale; in other words, challenges of cell-to-cell variability are minimized. We hypothesize “trapped” lithiated phases formed in the Si anode no longer contribute to electrochemical cycling and thus limit capacity in subsequent cycles/aging. We also characterized the SEI/surface species in situ with aging via 13C NMR measurements, identifying reactions of lithium silicides with electrolyte solvents and their subsequent decomposition.

Leaf relative water content at 50% stomatal conductance measured by noninvasive NMR is linked to climate of origin in nine species of eucalypt.

Stomata are the gatekeepers of plant water use and must quickly respond to changes in plant water status to ensure plant survival under fluctuating environmental conditions. The mechanism for their closure is highly sensitive to disturbances in leaf water status, which makes isolating their response to declining water content difficult to characterise and to compare responses among species. Using a small-scale non-destructive nuclear magnetic resonance spectrometer as a leaf water content sensor, we measure the stomatal response to rapid induction of water deficit in the leaves of nine species of eucalypt from contrasting climates. We found a strong linear correlation between relative water content at 50% stomatal conductance (RWCgs50 ) and mean annual temperature at the climate of origin of each species. We also show evidence for stomata to maintain control over water loss well below turgor loss point in species adapted to warmer climates and secondary increases in stomatal conductance despite declining water content. We propose that RWCgs50 is a promising trait to guide future investigations comparing stomatal responses to water deficit. It may provide a useful phenotyping trait to delineate tolerance and adaption to hot temperatures and high leaf-to-air vapour pressure deficits.

Cavitation‐Associated Water Evaporation From Porous Media Through In Situ NMR Characterization

AbstractEvaporation of water from porous media is essential for a large variety of applications, whereas the opacity of porous matrix imposes considerable challenges in unveiling complicated phase‐change phenomena. Air invasion was previously reported as the major desaturation mechanism, while cavitation in porous media is not well studied. Herein we characterize the transient distribution and evaporation of water in homogeneous tight porous media with nondestructive nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI). By monitoring the amplitude change of NMR transverse relaxation time T2, we investigate the dynamical pore filling status and water content during evaporation. Interestingly, we find that the T2 spectrum shifts immediately after the evaporation starts, indicating the emptying of big pores from the entire medium. Disconnected void clusters at different depths in the porous medium are also observed from MRI scanning and optical images. These observations indicate the emergence of cavitation across the entire porous media along with the evaporation from open surface. Cavitation occurs when the water is stretched to metastable state by large capillary pressure from the evaporating meniscus. By studying the evaporation from hydrophilic membrane‐separated porous media, we further demonstrate the existence of cavitation‐associated evaporation. The preferential water vaporization from the bottom part can still be found from T2 spectrum analysis and optical imaging even when the water‐permeable membrane cuts off possible air invasion. Our findings confirm cavitation‐associated evaporation is one of the primary mechanisms for tight porous media, which provides valuable guidance for evaporation and moisture control.

Detailed investigation of capillary active insulation materials by 1H nuclear magnetic resonance (NMR) and thermogravimetric drying

Capillary active interior insulation materials are an important and innovative approach to minimize energy losses of historical buildings. In an experimental setup, we investigate the development of moisture profiles under realistic boundary conditions to determine the liquid moisture conductivity for two different interior insulation materials. The moisture profiles were determined by destructive sample cutting with subsequent thermogravimetric drying as well as directly measured by the non-destructive method NMR, which has a higher spatial resolution and even enables repetitive measurements during the course of the experiments. We observed that the moisture profiles obtained from both methods showed good agreement, when compared at the low spatial resolution of sample cutting. This raises confidence in the method of simple mechanical sample cutting. In the next step, the liquid moisture conductivity was calculated using an inverse modelling approach based on both measured moisture profiles separately. Then, we compared the pore-size distributions of the investigated samples based on NMR T2-relaxation-time distributions, mercury intrusion porosimetry and indirect determination from pressure plate and sorption isotherm measurements. Moreover, the measured T2-relaxation-time distributions across the sample depth may give further insight into the saturation degree of the different pore sizes.

Study on Microstructure Differences of Coal Samples before and after Loading

The microscopic pore structure of coal affects the content of adsorbed gas. The microstructure of coal sample before and after loading is different, which will affect the adsorption and permeability of coal seam gas. In order to study this difference, the authors carried out mercury intrusion experiments on coal containing different coal samples and used nondestructive nuclear magnetic resonance (NMR) techniques, scanning electron microscopy, and transmission electron microscopy, to study the microstructure of coal samples before and after loading. The experimental results show that the pores of coal samples are mainly micropores and small pores, and the mesopores and macropores are relatively few. The T2 spectrum area of the coal sample is significantly increased after loading, and the parallel-layer coal samples’ T2 spectrum area is 46735, which is 9112 more than the vertical layer coal samples. The T2 spectrum of the vertical coalbed of saturated water samples shows a three-peak shape, the peak of the T2 spectrum is 12692, and the parallel bedding shows a bimodal morphology. The peak area of the T2 spectrum is 11277. The permeability of the parallel bedding coal sample is good, and the coal sample exhibits anisotropic properties. The pores and cracks of the coal samples increased after loading, and the localized area of the coal sample collapsed and formed a fracture zone, which was not conducive to the occurrence of coal seam gas. Further explanation of the changes in the permeability of the coal sample before and after loading will affect the gas storage and transportation.

Using pore size distribution and porosity to estimate particle size distribution by nuclear magnetic resonance

Soil particle size distribution (PSD) is critical for assessing the potential for internal instability of sand–gravel soils, mainly because particle migration in sand–gravel soils owing to seepage forces affects almost all soil hydraulic properties during internal erosion processes. Therefore, a reliable PSD analysis is essential for revealing the mechanism of particle migration and internal instability of sand–gravel soils. At present, however, PSD is commonly calculated by manual interpretation methods and cannot be continuously and nondestructively analyzed during internal erosion processes. Those methods are lacking, however, in that it results in a failure to continuously determine the internal erosion condition. In this paper, a new approach with the ability to continuously predict the PSD changes in sand–gravel mixtures is introduced based on one-dimensional laboratory suffusion tests in a non-destructive nuclear magnetic resonance (NMR) system over a range of suffusion times. The results show that pore expansion and particle migration are an interactive process that controls suffusion development in sand–gravel mixtures. The proposed method is verified through experimental data measured by sieve analysis, and has potential to retrieve PSD information at different suffusion times.

Food Safety Risk Assessment of γ-Butyrolactone Transformation into Dangerous γ-Hydroxybutyric Acid in Beverages by Quantitative 13C-NMR Technique

Food safety remains a matter of great concern in most countries and the composition in food is crucial to food safety. It is very important to make sense of the quality and change of food ingredients. In this research, the change of γ-butyrolactone (GBL), one kind of food additive in beverage, had been evaluated by nuclear magnetic resonance (NMR) technique. The 1H-NMR results of seven beverages covering various kinds with spiked GBL indicated that GBL was transformed into dangerous γ-hydroxybutyric acid (GHB) in six popular beverages under certain conditions which could happen during transportation and storage. Further results of quantitative 13C-NMR showed that pH and temperature were two key factors affecting the transforming degree of GBL to GHB. Lower pH and higher temperature will increase the degree of transformation. GHB was a neurotransmitter on the chemical control list, which was absolutely forbidden to be added to food. This nondestructive NMR detecting technology which did not need the complex pretreatment method to directly determine food ingredients can be useful for identifying the risk of food safety from the changes of food composition during transport and storage.

Experimental Investigation of the Mechanical Failure Behavior of Coal Specimens With Water Intrusion

Mining fissures formed by coal mining can easily open bedrock and loose aquifers, and can thus cause water–rock interaction. The strength of coal and rock and their pore and fracture development characteristics are closely related to moisture content. Therefore, this paper studied the strength, porosity, fracture propagation, and failure characteristics of coal with different moisture contents. Six representative coal samples with different moisture contents of 0, 3.79, 6.10, 9.17, 11.01, and 11.68% were prepared by non-destructive water immersion experiment, and the samples were analyzed using. Nuclear Magnetic Resonance (NMR) and uniaxial compression acoustic emission experiments. Then, the temporal and spatial variation of the moisture contents of the coal samples and the characteristics of crack propagation and failure were studied before and after water immersion. Non-destructive water immersion and NMR analysis showed that the moisture content increases exponentially with increasing water immersion time and immersion frequency. Additionally, it was shown that with increasing water immersion time and frequency, the moisture distribution within the coal samples changes from uneven to uniform, and micro-pores and meso-pores develop into larger pores with increasing water content. A coupled uniaxial compression–acoustic emission experiment showed that acoustic emissions are closely related to the macroscopic failure mode of the coal sample. With increasing sample moisture content, the degree of sample destruction and the concentration of acoustic emissions both reduced. The increase of moisture content promotes the change of the macroscopic failure mode of the coal samples from tensile failure to tensile–shear composite failure. The results of this study have important reference value for analyzing the stability of coal pillars and surrounding rock under the action of water, and especially for the design of coal pillar dam bodies in coal mines with groundwater reservoirs.

Metabolomics: A Way Forward for Crop Improvement.

Metabolomics is an emerging branch of “omics” and it involves identification and quantification of metabolites and chemical footprints of cellular regulatory processes in different biological species. The metabolome is the total metabolite pool in an organism, which can be measured to characterize genetic or environmental variations. Metabolomics plays a significant role in exploring environment–gene interactions, mutant characterization, phenotyping, identification of biomarkers, and drug discovery. Metabolomics is a promising approach to decipher various metabolic networks that are linked with biotic and abiotic stress tolerance in plants. In this context, metabolomics-assisted breeding enables efficient screening for yield and stress tolerance of crops at the metabolic level. Advanced metabolomics analytical tools, like non-destructive nuclear magnetic resonance spectroscopy (NMR), liquid chromatography mass-spectroscopy (LC-MS), gas chromatography-mass spectrometry (GC-MS), high performance liquid chromatography (HPLC), and direct flow injection (DFI) mass spectrometry, have sped up metabolic profiling. Presently, integrating metabolomics with post-genomics tools has enabled efficient dissection of genetic and phenotypic association in crop plants. This review provides insight into the state-of-the-art plant metabolomics tools for crop improvement. Here, we describe the workflow of plant metabolomics research focusing on the elucidation of biotic and abiotic stress tolerance mechanisms in plants. Furthermore, the potential of metabolomics-assisted breeding for crop improvement and its future applications in speed breeding are also discussed. Mention has also been made of possible bottlenecks and future prospects of plant metabolomics.

Nuclear magnetic resonance-based metabolomic investigation reveals metabolic perturbations in PM2.5-treated A549 cells.

Exposure to PM2.5 is associated with an increased risk of lung diseases, and oxidative damage is the main reason for PM2.5-mediated lung injuries. However, little is known about the early molecular events in PM2.5-induced lung toxicity. In the present study, the metabolites in PM2.5-treated A549 cells were examined via a robust and nondestructive nuclear magnetic resonance (NMR)-based metabolic approach to clarify the molecular mechanism of PM2.5-induced toxicity. NMR analysis revealed that 12 metabolites were significantly altered in PM2.5-treated A549 cells, including up-regulation of alanine, valine, lactate, ω-6 fatty acids, and citrate and decreased levels of gamma-aminobutyric acid, acetate, leucine, isoleucine, D-glucose, lysine, and dimethylglycine. Pathway analysis demonstrated that seven metabolic pathways which included alanine, aspartate and glutamate metabolism, aminoacyl-tRNA biosynthesis, taurine and hypotaurine metabolism, arginine and proline metabolism, starch and sucrose metabolism, valine, leucine and isoleucine biosynthesis, and tricarboxylic acid cycle were mostly influenced. Our results indicate that NMR technique turns out to be a simple and reliable method for exploring the toxicity mechanism of air pollutant.

Water dynamics of turbot flesh during frying, boiling, and stewing processes and its relationship with color and texture properties: Low-field NMR and MRI studies

Water dynamics in turbot flesh during frying, boiling and stewing was assessed by nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) techniques. Protons associated with different types of water were distinguished by T2 relaxation spectra, and significant differences of water mobility were detected. Principle component analysis revealed a clear discrimination between samples of different cooking methods. MRI provided further visualization of internal information for turbot flesh during cooking. The linear regression analysis demonstrated a strong correlation between the NMR parameter A23 and b* value (R2 = .972) during frying process, A23 and L* (R2 = .963), T22 and b* (R2 = .991) during boiling process, T22 and b* (R2 = .883) during stewing process. Moreover, a good correlation was found between A21 and cohesiveness (R2 = .924) during the frying process, A23 and resilience (R2 = .879) during boiling process, as well as between A23 and chewiness (R2 = .946) during stewing process. Practical applications Water mobility and distribution can significantly affect turbot flesh physical and biochemical status leading to change the texture, color, tenderness and taste during cooking process. Therefore, it is very important to develop a fast, nondestructive method to monitor the water dynamics, reduce the cooking time, save energy and visualize the structure change of turbot flesh during cooking. In this study, a rapid and nondestructive NMR and MRI method were developed to analyze the water dynamics of turbot flesh during frying, boiling and stewing for the first time. The water states, distribution and mobility were analyzed by the NMR and MRI. Different cooking methods displayed different water dynamics in turbot flesh, which could be identified when NMR combined with chemometrics principal component analysis. The facile method by using both NMR and MRI for analysis of turbot flesh may have great potential for rapid and nondestructive analysis of other food processing.

Dynamics of water mobility and distribution in Sur clam (Mactra chinensis) during dehydration and rehydration processes assessed by low-field NMR and MRI

Drying method effects on water dynamics in Sur clam during dehydration and rehydration were studied using the non-destructive nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) techniques. Three water populations were observed in Sur clam samples with different migration behavior when they were dried by hot air at 60 °C for 8 h versus sun-dried for 53 h. Good correlation between the A2 parameter of NMR and moisture ratio MR was found, and the Page model exhibited the maximum coefficient R2 value with the minimum root mean squared error. Notably, the NMR and MRI characterization showed that the water release of hot-air dried clams was different from that of the sun-dried samples, and the principal component analysis (PCA) of NMR relaxation data offered a stable classification for the hot-air dried and sun-dried clams. Similarly, the rehydration of hot-air dried and sun-dried clams was also assessed by NMR and MRI revealing that the absorbed water was mainly the immobilized and free water. The proper rehydration time was 180 and 120 min, respectively, for the hot-air and sun dried clams. The rehydrated clams could be distinguished from the boiled samples before dehydration process through the PCA of NMR relaxation data, but undistinguishable between the rehydrated hot-air dried and sun-dried clams. These results demonstrated that NMR and MRI are effective methods for non-destructive analysis of Sur clams during dehydration and rehydration processes.

Nondestructive Measurements of Cottonseed Nutritional Trait Diversity in the U.S. National Cotton Germplasm Collection

ABSTRACTRecent studies have suggested that cottonseed (Gossypium spp.) has the potential to contribute to the effort against world hunger, particularly by providing a high‐quality protein source. This report analyzed the diversity in protein content and other seed quality factors in the U.S. National Cotton Germplasm Collection. Nine genomes (one tetraploid and eight diploid) and 33 species (five tetraploid and 28 diploid) were surveyed in this examination of 2256 accessions. A novel nondestructive nuclear magnetic resonance technique was applied to measure oil and protein content, seed indices were calculated, and these data were associated with molecular marker information. Oil content ranged from 8 to 27%, protein values ranged from 10 to 36%, and seed index was lowest at 1 g per 100 seeds and extended up to 18 g per 100 seeds. Most of the range in values for these traits resided within G. hirsutum L. and G. barbadense L.; thus implying that variability for cottonseed quality can be introduced with relative ease in current breeding programs. The diploid genomes generally had extremely low values for oil, protein, and seed index. Molecular marker information indicated that chromosome 21 was likely associated with oil content. Understanding how these seed quality factors vary independently and in relation to each other will allow us to better select parents for breeding programs, and identifying associations with molecular markers may help us enhance progress through marker‐assisted selection approaches.

Rapid determination of total conjugated linoleic acid concentrations in beef by 1H NMR spectroscopy

Nuclear magnetic resonance (NMR) spectroscopy was employed to determine the conjugated linoleic acid (CLA) content in beef muscle tissue. NMR is an inviting and greener alternative to traditional methods such as gas chromatography (GC), which can require time-consuming sample derivatization and use of large quantities of solvents. In this work, a new rapid and reliable lipid extraction protocol was combined with simple, non-destructive 1H NMR spectroscopic analysis to measure the total CLA content in 41 Canadian beef ribeye steaks purchased in western Canada. The total CLA concentrations (mg/100g meat) obtained using the new extraction and analysis methods were consistent with amounts found using the traditional lipid extraction and GC analysis (correlation coefficient of 0.961).

HRMAS NMR Analysis of Algae and Identification of Molecules of Interest via Conventional 1D and 2D NMR: Sample Preparation and Optimization of Experimental Conditions.

Nuclear magnetic resonance (NMR) has become an astounding tool for molecular characterization. Thanks to the development of probes and the increase of magnetic field, NMR has entered the field of biology and facilitated the identification of natural compounds. Indeed, this nondestructive NMR tool makes possible the complete characterization of less and less quantities of material via 1D and 2D sequences on many nuclei (e.g., (1)H, (13)C, (31)P, (15)N). More recently, the development of high-resolution magic-angle spinning (HRMAS) probes have permitted direct analysis of living tissue (e.g., a piece of algae) without prior extraction providing information on both the total content and the ratio of different molecules within the sample; thus HRMAS facilitates a wide range of analyses, such as species differentiation or studies of metabolomics according to various environmental or experimental conditions. This chapter describes the specific sample preparation, based on an algal sample or extract, required for all NMR analyses in order to optimize the NMR response and obtain the most valuable information.

Characterization of synthesized NANO-encapsulated drug for bone loss on hind limb suspension rat model by NMR and micro-CT.

A formulation of nano-encapsulated enantiomer of (+) promethazine with desired release rate has been synthesized for establish a localized drug delivery system. It was tested on a hind limb suspension (HLS) disuse rat model, and by using a non-destructive Nuclear Magnetic Resonance (NMR) relaxation technique, and micro computed tomography (Micro-CT) analysis technique to qualitatively evaluate the effectiveness of the new bone formations as well as to compare the current commercial anti-bone loss drug Alendeonate. Our studies suggest that nano-encapsulated (+) promethazine in controlled release formulations conjugating bone-targeting functional groups are effective in promoting bone growth in a disuse rat model.

The effects of soy on freezable bread dough: A magnetic resonance study

Hygroscopic soy ingredients were hypothesised to slow the rate of water migration in unleavened bread dough during frozen storage. Thawed soy (18% dry weight) and wheat dough samples were assessed using non-destructive nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) for up to 8wks frozen storage time. MRI suggested a spatially homogeneous, net increase in proton mobility with frozen storage and, with solution state proton NMR, distinct “free” and “bound” states were discerned. T2 relaxation times of the majority proton population suggested increased mobility with frozen storage time, and statistical difference from the fresh sample was seen later for the soy samples than the wheat samples. As seen by 13C-solid state NMR, the crystallinity of the starch was not affected by either soy addition or frozen storage. In conclusion, addition of soy to bakery products led to slightly enhanced preservation of “fresh” characteristics of the dough during frozen storage.

Portable Microcoil NMR Detection Coupled to Capillary Electrophoresis

High-efficiency separation techniques, such as capillary electrophoresis (CE), coupled to a nondestructive nuclear magnetic resonance (NMR) spectrometer offer the ability to separate, chemically identify, and provide structural information on analytes in small sample volumes. Previous CE-NMR coupled systems utilized laboratory-scale NMR magnets and spectrometers, which require very long separation capillaries. New technological developments in electronics have reduced the size of the NMR system, and small 1-2 T permanent magnets provide the possibilities of a truly portable NMR. The microcoils used in portable and laboratory-scale NMR may offer the advantage of improved mass sensitivity because the limit of detection (LOD) is proportional to the coil diameter. In this work, CE is coupled with a portable, briefcase-sized NMR system that incorporates a microcoil probe and a 1.8 T permanent magnet to measure (19)F NMR spectra. Separations of fluorinated molecules are demonstrated with stopped- and continuous-flow NMR detection. The results demonstrate that coupling CE to a portable NMR instrument is feasible and can provide a low-cost method to obtain structural information on microliter samples. An LOD of 31.8 nmol for perfluorotributylamine with a resolution of 4 ppm has been achieved with this system.

Non-destructive characterization of microdamage in cortical bone using low field pulsed NMR

The microcracking and damage accumulation process in human cortical bone was characterized by performing cyclic loading under four-point bending at ambient temperature. A non-destructive nuclear magnetic resonance (NMR) spin–spin ( T 2 ) relaxation technique was applied to quantify the apparent changes in bone porosity as a function of cyclic loading and prior damage accumulation, first to unloaded cortical bone to quantify the initial porosity and then to fatigued cortical bone that was subjected to cyclic loading to various levels of modulus degradation and microdamage in the form of microcracks. The NMR T 2 relaxation time and amplitude data of the fatigued bone were compared against the undamaged state. The difference in the T 2 relaxation time data was taken as a measure of the increase in pore size, bone porosity or microcrack density due to microdamage induced by cyclic loading. A procedure was developed to deduce the number and size distributions of microcracks formed in cortical bone. Serial sectioning of the fatigued bone showed the formation of microcracks along the cement lines or within the interstitial tissue. The results on the evolution of microdamage derived from NMR measurements were verified by independent experimental measurements of microcrack density using histological characterization techniques. The size distribution and population of the microcracks were then utilized in conjunction with an analytical model to predict the degradation of the elastic modulus of cortical bone as a function of damage accumulation.

Percolation and survival of Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium in soil amended with contaminated dairy manure or slurry.

The effect of cattle manure and slurry application on percolation and survival of Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium was investigated for different soil depths after the addition of water. Four treatments were chosen for the first set of experiments: (i) addition of inoculated farmyard manure on the soil surface, (ii) mixing of inoculated farmyard manure with the top 10 cm of soil, (iii) addition of inoculated slurry on the soil surface, and (iv) injection of inoculated slurry into the top 10 cm of the soil. Homogeneity of water distribution in the soil profile was confirmed by a nondestructive nuclear magnetic resonance method. Survival data were fitted to a modified logistic model, and estimated survival times were compared. In the second set of experiments, pathogen-inoculated farmyard manure or slurry was applied to soil columns with 1-month-old lettuce plants. More pathogen cells percolated to greater depths after slurry than after manure application. Survival of E. coli O157:H7 was significantly longer in soil with slurry than in that with manure, while survival of Salmonella serovar Typhimurium was equally high with manure and slurry. The densities of the pathogens were not different in the rhizosphere compared to the bulk soil with manure, while the densities were higher by 0.88 +/- 0.11 and 0.71 +/- 0.23 log CFU per g (dry weight), respectively, in the rhizosphere than in bulk soil after slurry application. Our results suggest that surface application of manure may decrease the risk of contamination of groundwater and lettuce roots compared to injection of slurry.