Search Results (288)

Background/Objectives: Tegoprazan (TPZ) is a potassium-competitive acid blocker (P-CAB) used to treat conditions such as gastroesophageal reflux disease, peptic ulcer, and Helicobacter pylori infection. It exists in three solid forms: amorphous, Polymorph A, and Polymorph B. This study investigates the molecular basis of polymorph selection, focusing on conformational bias and solvent-mediated phase transformations (SMPTs). Methods: The conformational energy landscapes of two TPZ tautomers were constructed using relaxed torsion scans with the OPLS4 force field and validated by nuclear Overhauser effect (NOE)-based nuclear magnetic resonance (NMR). Hydrogen-bonded dimers were analyzed using DFT-D. Powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), solubility, and slurry tests were conducted using methanol, acetone, and water. Kinetic profiles were modeled with the Kolmogorov–Johnson–Mehl–Avrami (KJMA) equation. Results: Polymorph A was thermodynamically stable across all analyses. Both amorphous TPZ and Polymorph B converted to A in a solvent-dependent manner. Methanol induced direct A formation, while acetone showed a B → A transition. Crystallization was guided by solution conformers and hydrogen bonding. Conclusions: TPZ polymorph selection is governed by solution-phase conformational preferences, tautomerism, and solvent-mediated hydrogen bonding. DFT-D and NMR analyses showed that protic solvents favor the direct crystallization of stable Polymorph A, while aprotic solvents promote the transient formation of metastable Polymorph B. Elevated temperatures and humidity accelerate polymorphic transitions. This crystal structure prediction (CSP)-independent strategy offers a practical framework for rational polymorph control and the mitigation of disappearing polymorph risks in tautomeric drugs. Full article

Nuclear Magnetic Resonance (NMR) and Magnetic Resonance Imaging (MRI) are powerful techniques that have been employed to analyze foodstuffs comprehensively. These techniques offer in-depth information about the chemical composition, structure, and spatial distribution of components in a variety of food products. Quantitative NMR is widely applied for precise quantification of metabolites, authentication of food products, and monitoring of food quality. Low-field ¹H-NMR relaxometry is an important technique for investigating the most abundant components of intact foodstuffs based on relaxation times and amplitude of the NMR signals. In particular, information on water compartments, diffusion, and movement can be obtained by detecting proton signals because of H₂O in foodstuffs. Saffron adulterations with calendula, safflower, turmeric, sandalwood, and tartrazine have been analyzed using benchtop NMR, an alternative to the high-field NMR approach. The fraudulent addition of Robusta to Arabica coffee was investigated by ¹H-NMR Spectroscopy and the marker of Robusta coffee can be detected in the ¹H-NMR spectrum. MRI images can be a reliable tool for appreciating morphological differences in vegetables and fruits. In kiwifruit, the effects of water loss and the states of water were investigated using MRI. It provides informative images regarding the spin density distribution of water molecules and the relationship between water and cellular tissues. ¹H-NMR spectra of aqueous extract of kiwifruits affected by elephantiasis show a higher number of small oligosaccharides than healthy fruits do. One of the frauds that has been detected in the olive oil sector reflects the addition of hazelnut oils to olive oils. However, using the NMR methodology, it is possible to distinguish the two types of oils, since, in hazelnut oils, linolenic fatty chains and squalene are absent, which is also indicated by the ¹H-NMR spectrum. NMR has been applied to detect milk adulterations, such as bovine milk being spiked with known levels of whey, urea, synthetic urine, and synthetic milk. In particular, T2 relaxation time has been found to be significantly affected by adulteration as it increases with adulterant percentage. The ¹H spectrum of honey samples from two botanical species shows the presence of signals due to the specific markers of two botanical species. NMR generates large datasets due to the complexity of food matrices and, to deal with this, chemometrics (multivariate analysis) can be applied to monitor the changes in the constituents of foodstuffs, assess the self-life, and determine the effects of storage conditions. Multivariate analysis could help in managing and interpreting complex NMR data by reducing dimensionality and identifying patterns. NMR spectroscopy followed by multivariate analysis can be channelized for evaluating the nutritional profile of food products by quantifying vitamins, sugars, fatty acids, amino acids, and other nutrients. In this review, we summarize the importance of NMR spectroscopy in chemical profiling and quality assessment of food products employing magnetic resonance technologies and multivariate statistical analysis. Full article

Water’s unique physicochemical properties arise from its dynamic hydrogen-bonding network, yet the precise molecular threshold at which these cooperative behaviors emerge remains a key question. This study employed nuclear magnetic resonance (NMR) spectroscopy and density functional theory (DFT) calculations to investigate the evolution of hydrogen bonding strength in small water clusters, ranging from dimers to pentamers. The observed exponential increase in NMR chemical shift up to the pentamer reflects growing hydrogen bond cooperativity, identifying the (H₂O)₅ cluster as a critical structural and energetic threshold. At this size, the network achieves sufficient connectivity to support key bulk-like phenomena such as proton transfer and dielectric relaxation. These conclusions were corroborated by complementary FT-IR and electrochemical impedance spectroscopy (EIS) measurements of bulk water. Our results position the water pentamer as the molecular onset of emergent solvent behavior, effectively bridging the divide between discrete clusters and the macroscopic properties of liquid water. Full article

Determining the technological quality of fresh meat pieces is essential in the meat industry to ensure the production of high-quality products. For this purpose, nuclear magnetic resonance (NMR) is a non-destructive and non-invasive technique that appears as an alternative to traditional methodologies. The objective of this work is to determine the potential of magnetic resonance imaging (MRI) and time-domain (TD-NMR) relaxometry for determining the physicochemical characterization of fresh hams with different industrial destinations (both fresh and cured products, such as dry-cured ham). For this study, the biceps femoris, semimembranosus, and semitendinosus muscles of 20 fresh hind legs from white pigs, classified into four categories according to their fat content, were analyzed. The semitendinosus muscle was selected as a model, and positive and negative correlations were obtained between different physicochemical parameters and the longitudinal (T1) and transverse (T2) relaxation times obtained by MRI and TD-NMR. Regression models using T1 and T2 were also developed to predict the muscle water-holding capacity (WHC) and drip loss, using high, medium, and low magnetic field NMR (R² > 0.80). Therefore, MRI and TD-NMR could be considered as highly suitable and accurate non-destructive techniques for the WHC determination in the meat industry. Full article

Concrete printing technologies play a key role in the modernization of construction practices. One factor that mitigates their progress is the development of standards and characterization tools for concrete during printing. The aim of this work is to point out correlations between some printability descriptors of mortars and the data obtained from low-field nuclear magnetic resonance (NMR) relaxometry techniques. In this context, the superposed effects of an acrylic-based superplasticizer and calcium nitrate accelerator were investigated. The mortars under study are based on white Portland cement, fine aggregates, and silica fume at fixed ratios. Extrusion tests and visual inspection of the filaments evaluate the extrudability and the printing window. The selected compositions were also investigated via transverse $\left(T_2\right)$ and longitudinal $\left(T_1\right)$ NMR relaxation times. The results indicate that both additives increase the printing window of the mortar, while the accelerator induces a faster increase in specific surface area of capillary pores $\left(S/V\right)$ only after 30–60 min of hydration. Some correlations were found between the printing window and the range where the transverse relaxation rates $\left(1/T_2\right)$ and the pore surface-to-volume ratios $\left(S/V\right)$ increase linearly. This suggests some promising connections between NMR techniques and the study of structural buildup of cementitious materials. Full article

This study aims to investigate the application of nuclear magnetic resonance (NMR) to characterize mortars containing recycled rubber waste as an eco-innovative material for sustainable construction. The primary objective was to analyze the way rubber granules influence hydration kinetics, microstructural development and pore structure. The innovative mortar formulations incorporated rubber granules, casein, natural hydraulic lime (NHL), and latex. NMR analysis revealed distinct T₂ relaxation time distributions correlated with different pore sizes and water states: shorter T₂ values demonstrate strongly bound water in small pores, while longer T₂ values are associated with loosely bound or free water in larger pores. The formulation with 3.5% NHL and 5% rubber granules exhibited optimal microstructural characteristics. These results reveal that NMR is a valuable, non-destructive tool for monitoring cementitious material evolution and supporting the use of tire-derived waste in eco-innovative mortar designs. Full article

Aiming to obtain insight into the dynamic properties of ionogels, ¹H NMR relaxation experiments were performed for an ionogel composed of 1-butyl-3-methyl-imidazolium chloride [BMIM][Cl] and propylene carbonate. The experiments were conducted in the frequency range of 10 kHz to 20 MHz, spanning the temperature range of 273 K to 338 K. The data were analyzed in term s of a relaxation model including two relaxation contributions—one of them associated with anisotropic (two-dimensional) translation diffusion, the second one representing a power law dependence of spin-lattice relaxation rates on the resonance frequency. The power law relaxation term (characterized by a very low power law factor of about 0.1) was attributed to the collective dynamics of the partially immobilized propylene carbonate matrix, while the relaxation contribution associated with anisotropic translation diffusion was attributed to the movement of BMIM cations in the matrix; the translation diffusion coefficient was estimated as varying in the range of 10⁻¹³ m²/s–10⁻¹² m²/s. Moreover, other parameters were determined as a result of the analysis, such as the residence lifetime on the matrix surfaces. Subsequently, the temperature dependencies of the determined parameters were assessed. Full article

This study investigates the coupled effects of waste rock-to-tailings ratio (WTR) and curing temperature on the pore structure and mechanical performance of cemented tailings waste rock backfill (CTRB). Four WTRs (6:4, 7:3, 8:2, 9:1) and curing temperatures (20–50 °C) were tested. Low-field nuclear magnetic resonance (NMR) was used to characterize pore size distributions and derive fractal dimensions ($D_a$, $D_b$, $D_c$) at micropore, mesopore, and macropore scales. Uniaxial compressive strength (UCS) and elastic modulus (E) were also measured. The results reveal that (1) the micropore structure complexity was found to be a key indicator of structural refinement, while excessive temperature led to pore coarsening and strength reduction. $D_a$ = 2.01 reaches its peak at WTR = 7:3 and curing temperature = 40 °C; (2) at this condition, the UCS and E achieved 20.5 MPa and 1260 MPa, increasing by 45% and 38% over the baseline (WTR = 6:4, 20 °C); (3) when the temperature exceeded 40 °C, $D_a$ dropped significantly (e.g., to 1.51 at 50 °C for WTR = 7:3), indicating thermal over-curing and micropore coarsening; (4) correlation analysis showed strong negative relationships between total pore volume and mechanical strength ($R$ = −0.87 for ${\mathsf{\delta }}_a\mathrm{v}\mathrm{s}.\mathrm{U}\mathrm{C}\mathrm{S}),$ and a positive correlation between $D_a$ and UCS (R = 0.43). (5) multivariate regression models incorporating pore volume fractions, $T_2$ relaxation times, and fractal dimensions predicted $\mathrm{U}\mathrm{C}\mathrm{S}$ and E with R² > 0.98; (6) the hierarchical sensitivity of fractal dimensions follows the order micro-, meso-, macropores. This study provides new insights into the microstructure–mechanical performance relationship in CTRB and offers a theoretical and practical basis for the design of high-performance backfill materials in deep mining environments. Full article

The beam angle error of the pump light in a K-Rb-²¹Ne spin-exchange relaxation-free atomic co-magnetometer (SERFCM) significantly degrades the efficiency of optical pumping and the system’s ability to suppress magnetic field noise. In this work, a system response model that incorporates the pump beam alignment error (PBAE) is established. The influence of PBAE on the scale factor, bandwidth, and magnetic noise response of the inertial output is analyzed. Theoretical results show that PBAE increases the internal magnetic field gradient, reduces the efficiency of nuclear spin hyperpolarization, and increases the nuclear spin relaxation rate, ultimately degrading the system’s scale factor, bandwidth, and magnetic noise suppression capability. Experimental results demonstrate that, compared to the original SERFCM with PBAE, aligning the pump laser using the proposed method improves the polarization strength of nuclear spins by approximately 10% and enhances magnetic noise suppression by 40%. Full article

Although Mercury Intrusion Porosimetry (MIP) and Nuclear Magnetic Resonance (NMR) are widely used for pore characterization, their effectiveness is fundamentally constrained by theoretical limitations. This study investigated the pore structure characteristics of coal-bearing sandstones from the northeastern Ordos Basin using an integrated approach combining experimental measurements and model-based inversion. The experimental measurements comprised a stress-dependent acoustic velocity test (P- and S-wave velocities), X-ray diffraction (XRD) mineralogical analysis, and NMR relaxation T₂ spectra characterization. For model-based inversion, we developed an improved Mori-Tanaka (M-T) theoretical framework incorporating stress-sensitive pore geometry parameters and dual-porosity (stiff/soft) microstructure representation. Systematic analysis revealed four key findings: (1) excellent agreement between model-inverted and NMR-derived total porosity, with a maximum absolute error of 1.09%; (2) strong correlation between soft porosity and the third peak of T₂ relaxation spectra; (3) stiff porosity governed by brittle mineral content (quartz and calcite), while soft porosity showing significant correlation with clay mineral abundance and Poisson’s ratio; and (4) markedly lower elastic moduli (28.78%–51.85%) in Zhiluo Formation sandstone compared to Yan’an Formation equivalents, resulting from differential diagenetic alteration despite comparable depositional settings. The proposed methodology advances conventional NMR analysis by simultaneously quantifying both pore geometry parameters (e.g., aspect ratios) and the stiff-to-soft pore distribution spectra. This established framework provides a robust characterization of the pore architecture in Jurassic sandstones, yielding deeper insights into sandstone pore evolution within the Ordos Basin. These findings provide actionable insights for water hazard mitigation and geological CO₂ storage practices. Full article

Comprehensive assessment of pore structure and multiphase water distribution is critical to the flow and transport process in coalbed methane (CBM) reservoirs. In this study, nuclear magnetic resonance (NMR) and multifractal analysis were integrated to quantify the multiscale heterogeneity of nine medium- and high-rank coals under water-saturated and dry conditions. By applying the box-counting method to transverse relaxation time (T₂) spectra, multifractal parameters were derived to characterize pore heterogeneity and residual water distribution. The influencing factors of pore heterogeneity were also discussed. The results show that pore structures in high-rank coals (HCs) exhibit a broader multifractal spectrum and stronger rightward spectrum than those of medium-rank coals, reflecting micropore-dominated heterogeneity and the complexity induced by aromatization in HCs. The vitrinite content enhances micropore development, increasing the heterogeneity and complexity of pore structure and residual water distribution. Inertinite content shows opposite trends compared to vitrinite content for the effect on pore structure and water distribution. Volatile yield reflects coal metamorphism and thermal maturity, which inversely correlates with pore heterogeneity and complexity. Residual water mainly distributes to adsorption pores and pore throats, shortening T₂ relaxation (bound water effect) and reducing spectral asymmetry. The equivalence of the multifractal dimension and singularity spectrum validates their joint utility in characterizing pore structure. Minerals enhance pore connectivity but suppress complexity, while moisture and ash contents show negligible impacts. These findings provide a theoretical reference for CBM exploration, especially in optimizing fluid transportation and CBM production strategies and identifying CBM sweet spots. Full article

The pore structure of reservoir rocks was a crucial factor affecting hydrocarbon production. Accurately characterized the micropore structure of different types of rock reservoirs was of great significance for unconventional natural gas exploration. In this study, multiple observation methods (field emission scanning electron microscope (FESEM) and low-field nuclear magnetic resonance (LFNMR)) and physical tests (mercury injection capillary pressure (MICP)) were employed, and double logarithmic plots for fractal fitting were illustrated. The fractal dimension of 15 samples was calculated using fractal theory to systematically investigate the pore–fracture structure and fractal characteristics of hydrocarbon source rock (limestone, mudstone, and sandstone) samples from the Late Carboniferous Taiyuan Formation in the Huainan coalfield. MICP experiments revealed that sandstone reservoirs had larger and more uniformly distributed pore throats compared to mudstone and limestone, exhibiting superior connectivity and permeability. The T₂ spectrum characteristic maps obtained using LFNMR were also consistent with the pore distribution patterns derived from MICP experiments, particularly showed that sandstone types exhibited excellent signal intensity across different relaxation time periods and had a broader T₂ spectrum width, which fully indicated that sandstone types possess superior pore structures and higher connectivity. FESEM experiments demonstrated that sandstone pores were highly developed and uniform, with sandstone fractures dominated by large fractures above the micrometer scale. Meanwhile, the FESEM fractal dimension results indicated that sandstone exhibits good fractal characteristics, validating its certain oil storage capacity. Furthermore, the FESEM fractal dimension exhibited a good correlation with the porosity and permeability of the hydrocarbon source rock reservoirs, suggesting that the FESEM fractal dimension can serve as an important parameter for evaluating the physical properties of hydrocarbon source rock reservoirs. This study enriched the basic geological theories for unconventional natural gas exploration in deep coal-bearing strata in the Huainan coalfield. Full article

Ultra-high magnetic fields and high-sensitivity cryoprobes permit the achievement of a high S/N ratio in ¹³C detection experiments, thus making a ¹³C superWEFT (Super water eliminated Fourier transform) experiment feasible. ¹³C signals that are not visible using ¹H observed heteronuclear experiments, nor with established 2D ¹³C direct detection experiments, become easily observable when a ¹³C relaxation-based filter is used. Within this frame, optimal control pulses (OC pulses) have been, for the first time, applied to paramagnetic systems. Although the duration of OC pulses competes with relaxation, their application to paramagnetic signals has been successfully tested. OC pulses are much more efficient with respect to the phase- and amplitude-modulated ones routinely used at lower fields while providing bandwidth excitation profiles that are sufficient to meet the need to cover up to an 80 ppm spectral region. On the other hand, when paramagnetic relaxation is shorter than the duration of OC pulses, the use of hard, rectangular pulses is, at the present state of the art, the best approach to minimize the loss of signal intensity. Full article

In this study, three types of non-meat proteins, including soybean protein, wheat gluten, and whey protein, were used as additives to improve the 3D printing performance of chicken meat. The effects of non-meat proteins on rheological behavior, textural properties, moisture characteristics, and the microstructure of gels were investigated. Chicken meat paste without non-meat proteins added was taken as a control. Rheological results showed that the addition of non-meat proteins increased the apparent viscosity and the storage modulus of chicken meat paste. Textural properties of gels, including hardness, chewiness, cohesiveness, springiness, and resilience were also improved. The microstructure of gels with non-meat protein addition became denser and more compact, with improved connectivity. Nuclear magnetic resonance showed that the signals of bound water, immobilized water, and free water moved to the left towards lower relaxation time (p < 0.05) and part of immobile water and free water changed to bound water. The samples containing 15% soybean protein exhibited good shape-forming and shape-keeping capacities. There was an obvious increase in hardness (1991.40 ± 88.22 g), springiness (0.92 ± 0.00), cohesiveness (0.72 ± 0.01), gumminess (1299.14 ± 21.21), and resilience (0.34 ± 0.01) in these samples. The cooking loss of samples containing 15% soybean protein was 2.46 ± 0.36%, which was significantly lower than that of other treatments (p < 0.05). In summary, 15% soybean protein-added samples showed great potential for 3D printing. Full article

The reliability of the “last mile” of cold-chain logistics is crucial for food safety. This study investigated the effect of different packaging treatments on the quality of anhydrously preserved live Ruditapes philippinarum (R. philippinarum) in “last mile” cold chain disruption. The temperature profiles of three packaging treatments at ambient temperature (25 °C) were monitored. Quality assessment was conducted based on sensory scoring, survival rate, total viable count (TVC), water-holding capacity (WHC), pH, total volatile basic nitrogen (TVB-N), thiobarbituric acid-reactive substances (TBA), color, and texture. Low-frequency nuclear magnetic resonance (LF-NMR) and magnetic resonance imaging (MRI) were utilized to characterize the water state profile. The findings demonstrated a progressive increase in internal package temperature throughout the “last mile”, with packages containing additional ice packs more effectively maintaining lower temperature and restricting the migration of “hot spots” towards the center. Specifically, the package with three ice packs maintained a markedly lower temperature, which effectively inhibited microbial activity, lipid oxidation, and the production of alkaline substances, resulting in higher survival rates, water-holding capacity, texture, sensory acceptability, and immobilized water fraction. Furthermore, LF-NMR relaxation parameters showed strong correlations with various physicochemical indices, suggesting a potential approach for real-time quality monitoring. This study provides insights for maintaining live R. philippinarum quality during the “last mile”. Full article