Application Of Nuclear Magnetic Resonance Research Articles

The role of Nuclear Magnetic Resonance (NMR) spectroscopy in cattle metabolism

Nuclear Magnetic Resonance (NMR) spectroscopy is a powerful analytical tool that has significantly advanced the understanding of cattle metabolism. Nuclear Magnetic Resonance (NMR) spectroscopy plays a pivotal role in the study of cattle metabolism, offering distinct advantages over other spectrometric methods. NMR spectroscopy is a powerful analytical tool that provides detailed molecular insights by exploiting the magnetic properties of atomic nuclei. Unlike mass spectrometry and infrared spectroscopy, NMR does not require extensive sample preparation or destruction, preserving the integrity of biological samples. This non-invasive nature is particularly beneficial for longitudinal studies in cattle, where metabolic changes over time are of interest. One of the key strengths of NMR spectroscopy is its ability to simultaneously detect and quantify a broad range of metabolites in complex biological matrices, such as blood, urine, and tissue extracts. This comprehensive metabolic profiling is crucial for understanding the biochemical pathways and physiological states in cattle. NMR's high reproducibility and quantitative accuracy further enhance its suitability for metabolic studies, enabling precise monitoring of metabolic fluctuations in response to dietary changes, environmental stressors, or disease conditions. NMR spectroscopy also offers unique advantages in elucidating structural information about metabolites. Through multidimensional NMR techniques, researchers can determine the molecular structure and conformation of metabolites, providing deeper insights into metabolic functions and interactions. This structural elucidation is often challenging with other spectrometric methods, which may lack the resolution or require derivatization of samples. Moreover, NMR spectroscopy's non-destructive nature allows for the analysis of living tissues and in vivo studies, facilitating real-time monitoring of metabolic processes. This capability is instrumental in studying dynamic metabolic responses and adaptations in cattle under different physiological states. Additionally, the development of advanced NMR techniques, such as high-resolution magic angle spinning (HR-MAS) and hyperpolarization, has further expanded the scope of NMR applications in metabolic research. NMR spectroscopy stands out as a superior method for studying cattle metabolism due to its non-destructive approach, comprehensive metabolic profiling, structural elucidation capabilities, and potential for in vivo analysis. These advantages make NMR an indispensable tool in advancing our understanding of cattle metabolism and improving livestock health and productivity. Keywords: Nuclear Magnetic Resonance (NMR), Cattles, Metabolomics.

Dynamic NMR methodology for kinetic studies

NMR (Nuclear magnetic resonance) is a popular tool used to characterize the structure of molecules, which is widely used for its high precision and accurate results. Due to these advantages, the NMR technique has been developed for monitoring the changes in the components during a reaction. This is called dynamic NMR technology. The kinetic measuring of a reaction is an important application of dynamic NMR, and the unique design of the methodology allows the NMR technique to be used for the determination of kinetic data such as reaction rates. In addition, dynamic NMR has also been used to monitor the reaction process and determine the reaction mechanism. Dynamic NMR techniques have developed rapidly in recent decades and have led to new research ideas and tools in chemistry and other related fields. In this paper, some examples of kinetic properties of reactions studied by dynamic NMR methods are introduced, including a summary of their development and prospects.

The Use of Spectroscopic Methods to Study Organic Matter in Virgin and Arable Soils: A Scoping Review

The use of modern spectroscopic methods of analysis, which provide extensive information on the chemical nature of substances, significantly expands our understanding of the molecular composition and properties of soil organic matter (SOM) and its transformation and stabilization processes in various ecosystems and geochemical conditions. The aim of this review is to identify and analyze studies related to the application of nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) spectroscopy techniques to study the molecular composition and transformation of organic matter in virgin and arable soils. This article is mainly based on three research questions: (1) Which NMR spectroscopy techniques are used to study SOM, and what are their disadvantages and advantages? (2) How is the NMR spectroscopy technique used to study the molecular structure of different pools of SOM? (3) How is ESR spectroscopy used in SOM chemistry, and what are its advantages and limitations? Relevant studies published between 1996 and 2024 were searched in four databases: eLIBRARY, MDPI, ScienceDirect and Springer. We excluded non-English-language articles, review articles, non-peer-reviewed articles and other non-article publications, as well as publications that were not available according to the search protocols. Exclusion criteria for articles were studies that used NMR and EPR techniques to study non-SOM and where these techniques were not the primary methods. Our scoping review found that both solid-state and solution-state NMR spectroscopy are commonly used to study the structure of soil organic matter (SOM). Solution-phase NMR is particularly useful for studying soluble SOM components of a low molecular weight, whereas solid-phase NMR offers advantages such as higher 13C atom concentration for stronger signals and faster analysis time. However, solution-phase NMR has limitations including sample insolubility, potential signal aggregation and reduced sensitivity and resolution. Solid-state NMR is better at detecting non-protonated carbon atoms and identifying heterogeneous regions within structures. EPR spectroscopy, on the other hand, offers significant advantages in experimental biochemistry due to its high sensitivity and ability to provide detailed information about substances containing free radicals (FRs), aiding in the assessment of their reactivity and transformations. Understanding the FR structure in biopolymers can help to study the formation and transformation of SOM. The integration of two- and three-dimensional NMR spectroscopy with other analytical methods, such as chromatography, mass spectrometry, etc., provides a more comprehensive approach to deciphering the complex composition of SOM than one-dimensional techniques alone.

Metabolomics and Proteomics in Prostate Cancer Research: Overview, Analytical Techniques, Data Analysis, and Recent Clinical Applications.

Prostate cancer (PCa) is a significant global contributor to mortality, predominantly affecting males aged 65 and above. The field of omics has recently gained traction due to its capacity to provide profound insights into the biochemical mechanisms underlying conditions like prostate cancer. This involves the identification and quantification of low-molecular-weight metabolites and proteins acting as crucial biochemical signals for early detection, therapy assessment, and target identification. A spectrum of analytical methods is employed to discern and measure these molecules, revealing their altered biological pathways within diseased contexts. Metabolomics and proteomics generate refined data subjected to detailed statistical analysis through sophisticated software, yielding substantive insights. This review aims to underscore the major contributions of multi-omics to PCa research, covering its core principles, its role in tumor biology characterization, biomarker discovery, prognostic studies, various analytical technologies such as mass spectrometry and Nuclear Magnetic Resonance, data processing, and recent clinical applications made possible by an integrative "omics" approach. This approach seeks to address the challenges associated with current PCa treatments. Hence, our research endeavors to demonstrate the valuable applications of these potent tools in investigations, offering significant potential for understanding the complex biochemical environment of prostate cancer and advancing tailored therapeutic approaches for further development.

Recent Applications of Unilateral NMR to Objects of Cultural Heritage

Although nuclear magnetic resonance (NMR) is recognized as a powerful tool in many areas of research, among the investigative techniques used in the field of cultural heritage its application is still largely unknown. One of the reasons for this is that artifacts are complex heterogeneous systems whose analysis requires a multi-disciplinary approach. In addition, major drawbacks in the analysis of objects belonging to cultural heritage are their limited quantity, number of samples collected from the artifact, and their immovability. Consequently, a methodological approach where non-destructive, and possibly non-invasive techniques are used, is advisable. In recent years, thanks to the development of portable instruments, there has been an increasing use of the NMR methodology in the cultural heritage field. The use of portable NMR has allowed us to study several materials in the cultural heritage, such as frescoes, stones, wood, paper, and paintings, to address the challenges in monitoring dampness in historical masonries, to evaluate the penetration depth of a hydrophobic treatment into a porous material, and to study of the effect of cleaning procedures on artifacts. In this paper, recent studies illustrating the potential of NMR portable methodologies in this field of research are reported.

An Investigation into the Applicability of Wideline NMR for the Determination of Oil in Waxes

AbstractThe applicability of solid‐state NMR (Nuclear Magnetic Resonance) for determination of oil content in waxes is probed by NMR experimental and data processing approaches. NMR is found to underestimate the value of the oil content in Fischer‐Tropsch (FT) waxes due to the ability of the wax to trap small domains of oil within the matrix during crystallisation. No clear relationship could be obtained between T2 relaxation time and oil content, even after applying corrections due to disparities between mass and proton densities. Near linear calibration curves could be obtained by isolating a true oil signal at −32 °C. Model studies using heptadecane as simple oil analogue proved that removing oil/wax interactions and only using the oil as a diluent, near linear calibration curves could be attained. Insight into the mechanism of oil retention in both FT and paraffin waxes is obtained, showing differences due to both molecular and morphological variation. Results showed that, due to underlying molecular interactions, linear calibration curves cannot necessarily be expected even when melting behaviour varies linearly. In applications where oil content plays a crucial role in wax properties, this knowledge enables the industry to make more informed decisions when discrepancies in wax performance arise.

Comparative drawability and recrystallization evaluation of Nb4Ta and Nb4Ta1Hf alloys, and the beneficial influence of Hf on developing finer Nb3Sn grain size

Nb3Sn superconducting wires with high critical current density (Jc, 4.2 K) at fields greater than 15 T are needed for next-generation superconducting magnets for high-energy physics and nuclear magnetic resonance applications. It has been demonstrated that the addition of one atomic % Hf can significantly increase the high field Jc of Ta-doped Nb3Sn and offer the potential to meet the Future Circular Collider (FCC) specification of 1500 A/mm2 at 16 T, 4.2 K if the pure Nb filaments in conventional Nb3Sn composites can be replaced by Nb4Ta1Hf alloy. In this paper we demonstrate that a commercially produced Nb4Ta1Hf alloy is ductile and drawable in a Cu matrix to a large true strain of 15 without intermediate annealing. The hardness and work-hardening rates of Nb4Ta1Hf are shown to be higher than Nb and commercial Nb4Ta, but are comparable to ductile Nb47Ti alloy at high strains, which is significant because more than 1000 tons of Nb-Ti rods are co-drawn in Cu each year. Very importantly for the Nb3Sn properties is that just 1 at%Hf shifts the recrystallization curve of Nb4Ta to temperatures above the normal 600 °C −700 °C A15 range of reaction temperatures used for Nb3Sn wires. For the Hf-based 19 filament rod in tube (RIT) conductors of this study, we observe a refined (<100 nm) Nb3Sn grain size, and an improved upper critical field of 24.6 T (4.2 K), ∼1 T higher than that in a corresponding Nb4Ta composite. The demonstration of improved performance and good drawability with commercially produced Nb4Ta1Hf alloy indicates a pathway for Nb3Sn strand development for next-generation Nb3Sn magnets.

Analysis of complex mixtures with benchtop nuclear magnetic resonance: Solvent suppression with T2 and diffusion filters.

Benchtop nuclear magnetic resonance (NMR) spectrometers are being employed in a wide variety of applications from undergraduate teaching and research in academia to quality control and process monitoring in industrial settings. Incorporating benchtop NMR in some of these applications presents opportunities for new practical uses of the technology and challenges that truly test the capabilities of compact NMR spectrometers. For instance, the use of protonated solvents in manufacturing or process monitoring requires separating and quantitating the analyte signals of interest from the strong (overwhelming) response from the solvents. Furthermore, due to the lower field strength available with permanent magnet spectrometers, the NMR spectra of complex mixtures can be more difficult to analyze due to partial or complete signal overlap. To address some of these challenges and to extend the range of applications of benchtop NMR, we investigate NMR techniques that enable quantitative analysis of different components in mixtures. These pulse sequences can be used to suppress one or multiple solvent peaks, to filter out signals by spin-spin relaxation time (T2), or to separate signal components by a molecule's diffusion coefficient (NMR diffusometry). In this paper, we discuss quantitative analysis of excipients in buffers for therapeutic proteins to highlight the usefulness of these NMR pulse sequences in the analysis of complex samples with benchtop NMR spectrometers.

Resistance at 77 K of two Bi-2223 coils with superconducting joints prepared by incongruent melting

A superconducting joint for multi-filamentary Bi2Sr2Ca2Cu3O10+δ (Bi2223) tape, which has applications in nuclear magnetic resonance and magnetic resonance imaging, has been developed based on incongruent melting and multi-junction methods. In this study, the critical current limit, optimal oxygen annealing conditions, and reproducibility of this joint are experimentally evaluated. The results indicate that the critical current limit of the joint at 77 K is determined by that of the tape. The critical current limit was estimated to be about 40 A. Additional oxygen annealing after heat treatment below 1143 K. appears to have no effect on the critical current, and that above 1153 K slightly increases the critical current. It is found that the multi-junction method effectively increases the reproducibility of obtaining a high critical current. To obtain a high critical current at 77 K, the highest temperature in the joint creation process should be lowered to near the incongruent melting temperature of Bi2223 (about 1133 K in air). Two Bi2223 coils, each with one joint (four junctions), were prepared and their persistent current at 77 K was tested. A persistent current of above 20 A was measured with a resistance of about 10 pΩ.

The application of High-Resolution Nuclear Magnetic Resonance (HR NMR) in metabolomic analyses of meconium and stool in newborns. A preliminary pilot study of MABEL project: Metabolomics approach for the assessment of Baby-Mother Enteric Microbiota Legacy

BackgroundThe microbial population living in our intestines plays a key role in several metabolic, nutritional, physiological, and immunological processes. It is known that infant gut microbiota composition has both horizontal transmission delivery and environmental conditions and a vertical one, from mother to child, related to how the infant is fed (breastfed or infant formula). Detailed information on the composition of meconium and feces from newborns may help predict the most prevalent and hazardous conditions affecting pregnancies, mothers, and babies, including pre-term birth, preeclampsia, and gestational diabetes mellitus for example. MethodsThis work aims to demonstrate the feasibility of the whole High-Resolution proton Nuclear Magnetic Resonance (1H HR NMR) procedure in metabolomic analysis in preterm newborns. Thus, multiple samples of meconium and stool were collected from 3 pairs of premature twins and their metabolite profiles were acquired and exploited by combining the NMR technique with univariate and multivariate analysis. ResultsThe analysis showed that an impact on the metabolite profile was visible concerning both the sex of the newborns and the couplet of origin. Most of the variation between twin couplets was seen with butyric acid concentration in meconium/stool samples. ConclusionsDespite the low number of samples, the described NMR procedure showed to be a suitable approach to evaluate the similarities of the molecular profiles of different samples, offering a non-invasive and informative approach to understanding the metabolic and nutritional status of preterm infants. Future metabolomic analysis should be supported by microbiome analysis, such multiomic approach will provide more complex view on development of preterm newborns.

Determination of nuclear magnetic resonance surface relaxivity for the macropore system from wood cell lumen

To determine the surface relaxivity of pores plays a vital role in the application of time-domain nuclear magnetic resonance (TD-NMR) technology to porous structure characterization for wood. Currently, the surface relaxivity of pores is calibrated using a standard sample with a pore size of the same order as the wood pore system. However, the uniformly distributed pore size of standard sample is unfit to accurately indicate the complexity of porous structure of wood, which significantly affects the accuracy of test results. By integrating the TD-NMR technology with mercury intrusion porosimetry (MIP), the surface relaxivity of macropores in the lumen of wood cells is calibrated in this study using the tested sample, so as to avoid the error in measurement as caused by existing method. Data processing is performed using several mathematical methods including interpolation arithmetic and least square principle. Notably, the node segmentation method is applied to identify the T2 boundary of pores in cell lumen and to classify the porous structure of cell lumen into different pore systems. The approach proposed in this study is demonstrated to be effective in improving the accuracy of TD-NMR technology for characterizing the porous structure of wood. Also, it contributes a potential solution to accounting for the porous structure of wood based on the phenomenon of pore relaxation, which can improve the understanding of wood pore conformation.

NMR- and HRMS-based untargeted metabolomic study of metal-stressed Euglena gracilis cells

Environmental contamination is an increasing problem and one of the main threats to human health. While euglenoids have been shown to tolerate high levels of metals, little is known about the metabolic mechanisms at play. To address this gap, Euglena gracilis cells in the mixotrophic exponential phase were exposed to high levels of cadmium (Cd), cobalt (Co), or copper (Cu) (2.7–190.7 mg L−1) and the cellular metabolic profiles were explored using a multi-pronged untargeted approach. The combined application of proton nuclear magnetic resonance (1H NMR) and high-resolution mass spectrometry (HRMS) expanded the coverage of detected metabolites by 38–58 % using the computational platform Pathos and the metabolite databases KEGG, Metlin, and Chenomx. Only 3 % of the identified metabolites were found to be common to 1H NMR and HRMS. This low overlap indicates that the two methods complement each other, with each method uncovering a unique set of metabolites. Although four metabolic pathways including purine metabolism, alanine, aspartate, and glutamate metabolism, and the citrate cycle were common to all metal treatments, sixteen metabolic pathways were metal-specific. Notably, the metabolic alterations induced by Cd and Co differed from each other and the control, while the metabolic profile of Cu-treated cells resembled the control more closely. Unlike Co which showed a broad impact on Euglena gracilis metabolism, the stress induced by Cd and Cu exposure seems to target more the amino sugar production and the chlorophyll machinery, respectively. The observed metabolic alterations in response to various metals highlight a potential correlation with the generation of reactive oxygen species (ROS). Together these results contribute to a better understanding of cellular toxicity and the impacts of metal-induced oxidative stress in Euglena gracillis cells.

Solid-state NMR MAS CryoProbe enables structural studies of human blood protein vitronectin bound to hydroxyapatite

The low sensitivity of nuclear magnetic resonance (NMR) is a major bottleneck for studying biomolecular structures of complex biomolecular assemblies. Cryogenically cooled probe technology overcomes the sensitivity limitations enabling NMR applications to challenging biomolecular systems. Here we describe solid-state NMR studies of the human blood protein vitronectin (Vn) bound to hydroxyapatite (HAP), the mineralized form of calcium phosphate, using a CryoProbe designed for magic angle spinning (MAS) experiments. Vn is a major blood protein that regulates many different physiological and pathological processes. The high sensitivity of the CryoProbe enabled us to acquire three-dimensional solid-state NMR spectra for sequential assignment and characterization of site-specific water-protein interactions that provide initial insights into the organization of the Vn-HAP complex. Vn associates with HAP in various pathological settings, including macular degeneration eyes and Alzheimer's disease brains. The ability to probe these assemblies at atomic detail paves the way for understanding their formation.

Analyzing atomic scale structural details and nuclear spin dynamics of four macrolide antibiotics: erythromycin, clarithromycin, azithromycin, and roxithromycin.

The current investigation centers on elucidating the intricate molecular architecture and dynamic behavior of four macrolide antibiotics, specifically erythromycin, clarithromycin, azithromycin, and roxithromycin, through the application of sophisticated solid-state nuclear magnetic resonance (SSNMR) methodologies. We have measured the principal components of chemical shift anisotropy (CSA) parameters, and the site-specific spin-lattice relaxation time at carbon nuclei sites. To extract the principal components of CSA parameters, we have employed 13C 2DPASS CP-MAS SSNMR experiments at two different values of magic angle spinning (MAS) frequencies, namely 2 kHz and 600 Hz. Additionally, the spatial correlation between 13C and 1H nuclei has been investigated using 1H-13C frequency switched Lee-Goldburg heteronuclear correlation (FSLGHETCOR) experiment at a MAS frequency of 24 kHz. Our findings demonstrate that the incorporation of diverse functional groups, such as the ketone group and oxime group with the lactone ring, exerts notable influences on the structure and dynamics of the macrolide antibiotic. In particular, we have observed a significant decrease in the spin-lattice relaxation time of carbon nuclei residing on the lactone ring, desosamine, and cladinose in roxithromycin, compared to erythromycin. Overall, our findings provide detailed insight into the relationship between the structure and dynamics of macrolide antibiotics, which is eventually correlated with their biological activity. This knowledge can be utilized to develop new and more effective drugs by providing a rational basis for drug discovery and design.

Paramagnetic Nuclear Magnetic Resonance: The Toolkit

Nuclear Magnetic Resonance (NMR) spectroscopy is the ideal tool to address the structure, reactivity and dynamics of both inorganic and biological substances. The knowledge of nuclear spin interaction and spin dynamics is increasingly consolidated, and this allows for tailoring pulse sequences. When dealing with paramagnetic systems, several decades of research have led to the development of rule-of-the-thumb criteria for optimizing the experiments, allowing for the detection of nuclei that are in very close proximity to the metal center. In turn, the observation of these systems, coupled with the development of robust and accessible quantum chemical methods, is promising to provide a link between the spectra and the structural features through the interpretation of the electronic structure. In this review, we list the challenges encountered and propose solutions for dealing with paramagnetic systems with the greatest satisfaction. In our intentions, this is a practical toolkit for optimizing acquisition and processing parameters for routine experiments aimed at detecting signals influenced by the hyperfine interaction. The implications of paramagnetic shift and line broadening are examined. With this endeavor, we wish to encourage non-expert users to consider the application of paramagnetic NMR to their systems.

Richer than previously probed: An application of 1H NMR reveals one hundred metabolites using only fifty microliter serum

The classical approach restricts the detection of metabolites in serum samples by using nuclear magnetic resonance (NMR) spectroscopy; however, the presence of copious proteins and lipoproteins emphasize and necessitate the development of a contemporary, high-throughput tactic. To eliminate the lipoproteins and proteins from sera to engender filtered sera (FS), the study was executed with 50 μl serum obtained from five healthy individuals with 5 years of age difference from 25 to 45 years old and the application of a unique mechanical filter with molecular weight cut-off value of 2KDa. The 10 μl FS from each individual was pooled to make 50 μl final volume filled in a co-axial tube for acquisition of a battery of 1D/2D investigations at 800 MHz NMR spectrometer and the assigned metabolites was confirmed through mass spectrometry as well as by comparing 1H NMR spectra of individual metabolites. This innovative tactic is commissioning to reveal more than 100 metabolites. In contrast to the protein precipitation method, 24 new metabolites were recognized in the present study. The present innovative approach characterizes nucleosides, nitrogenous bases, and volatile metabolites that possibly produce a landmark for the delineation of a comprehensive metabolic profile applicable for detection of the molecular cause of pathogenicity, early-stage disease detection and prognosis, inborn error of metabolism, and forensic investigations exerting the least volume of FS and NMR spectroscopy. The assignment of 100 metabolites using 1H NMR-based FS is described for the first time in the present report.

Persistent MgB2 joints for react and wind magnets

Ultra-low resistance joints are a key technology enabling superconducting magnets to operate in persistent mode and to achieve the temporal stability required for nuclear magnetic resonance and magnetic resonance imaging (MRI) applications. High performance superconducting joints are manufactured routinely for Nb–Ti and Nb3Sn magnets, but technologies for joining other technological superconductors are still in the early stages of development. Here we report the use of a simple cold pressing and heat treatment procedure to fabricate persistent MgB2 joints with resistance values <10−12 Ω between MgB2 wires that have already undergone the full wire reaction process. Trapped persistent currents of 172 A and 160 A were achieved under self-field and 1 T background field conditions respectively at a temperature of 20 K. This corresponds to a critical current ratio of 78% under these conditions, outperforming previously reported joints using fully reacted MgB2 wire. These findings are relevant for the development of commercial MRI magnets with MgB2 wires utilizing react and wind methods.

A Review of Inline Infrared and Nuclear Magnetic Resonance Applications in Flow Chemistry

As a safe and efficient synthesis technique, flow chemistry has recently gained attention in the pharmaceutical, materials, and environmental protection industries. However, researchers always face challenges in handling samples and selecting sufficiently flexible analytical techniques. Generally, real-time process analysis is crucial for monitoring reactions. The combination of flow chemistry with real-time process analysis can be beneficial for studying reaction kinetics and thermodynamics, monitoring, and control of the chemical synthesis processes, reaction optimization of macro and microreactors, and qualitative and quantitative analyses of compounds. Thus far, studies investigating the combination of flow chemistry with inline monitoring have included ultraviolet–infrared spectroscopy, Raman spectroscopy, gas chromatography, mass spectrometry, liquid chromatography, nuclear magnetic resonance (NMR) spectroscopy, and other automated conventional or unconventional methods. This review sheds light on applying inline infrared and inline NMR spectroscopies in flow chemistry.

Applications of Two-Dimensional Laboratory Higher-Frequency NMR in Unconventional Shale Characterization

The complexity of the microstructure and fluids in unconventional reservoirs presents challenges to the traditional approaches to the evaluation of geological formations and petrophysical properties due to the low porosity, ultralow permeability, complex lithology, and fluid composition. Nuclear magnetic resonance (NMR) techniques have been playing major roles in unconventional shale characterization in the last decades as NMR can provide critical information about the reservoirs for quantifying their petrophysical parameters and fluid properties and estimating productivity. Laboratory NMR techniques at higher frequency (HF), e.g., 23 MHz, especially two-dimensional (2D) T1-T2 mapping, and their applications have been essential for the noninvasive characterization of tight rock samples for identifying kerogen, bitumen, heavy or light hydrocarbons, and bound or capillary water. Traditional T2 cutoffs, established with low frequency (LF) NMR, no longer apply and need new definitions to reflect the inferences from water and hydrocarbons separately. The crushed rock analysis method, as applied to unconventional formations, has been successful in evaluating total porosity and water saturation but also suffers from inconsistency in results due to desiccation and solvent effects. In the past decade, the oil and gas industry has witnessed significant development of HF NMR techniques that couple advances in petrophysics, petroleum engineering, and geochemistry with a broad range of applications. It is necessary to review such technological advances and draw conclusions to benefit unconventional core analysis programs. This article will summarize key advances in laboratory NMR applications in unconventional shale characterization, including monitoring processes of liquids equilibrium, desiccation, and imbibition in fresh shale samples, determination of activation energy of hydrocarbons in shales, monitoring changes in a shale sample during liquid flooding experiments, and direct measurements on kerogen.

Myr-Arf1 conformational flexibility at the membrane surface sheds light on the interactions with ArfGAP ASAP1

ADP-ribosylation factor 1 (Arf1) interacts with multiple cellular partners and membranes to regulate intracellular traffic, organelle structure and actin dynamics. Defining the dynamic conformational landscape of Arf1 in its active form, when bound to the membrane, is of high functional relevance and key to understanding how Arf1 can alter diverse cellular processes. Through concerted application of nuclear magnetic resonance (NMR), neutron reflectometry (NR) and molecular dynamics (MD) simulations, we show that, while Arf1 is anchored to the membrane through its N-terminal myristoylated amphipathic helix, the G domain explores a large conformational space, existing in a dynamic equilibrium between membrane-associated and membrane-distal conformations. These configurational dynamics expose different interfaces for interaction with effectors. Interaction with the Pleckstrin homology domain of ASAP1, an Arf-GTPase activating protein (ArfGAP), restricts motions of the G domain to lock it in what seems to be a conformation exposing functionally relevant regions.