Search Results (191)

Deep coalbed methane (CBM) represents a strategic successor field for unconventional oil and gas exploration and development in China, and fluid mobility is a key parameter determining CBM recovery rates. Existing NMR-based studies on coal rock pore structure and fluid mobility suffer from three deficiencies: a lack of coal rock classification based on T₂ spectral morphology, failure to incorporate fractal characteristics into pore classification, and insufficient understanding of fluid mobilization mechanisms in different pore types during gas-driven recovery. This study investigates deep coal rocks of the Taiyuan Formation in the Linxing Block, eastern Ordos Basin, using low-field nuclear magnetic resonance (LF-NMR), saturation gas displacement experiments, and fractal theory. Deep coal rocks were classified into three types based on T₂ spectral peak morphology under saturated conditions: Type I (central main peak), Type II (left-shifted main peak), and Type III (balanced bimodal peak). A fractal-based method was established to subdivide fluid-filled pores into four types: P1-1, P1-2, P1-3, and P2. Through multiple nitrogen displacement experiments, the fluid mobilization characteristics of each pore type at different displacement stages were quantitatively characterized. A fluid mobility index was proposed to comprehensively evaluate the overall fluid mobility of coal rocks. The results indicate that Type I coal rocks exhibit the highest fluid mobility (54.83% after three displacement cycles), with P1-3 pores as the primary mobile fluid reservoir, whereas Type II and Type III coal rocks show lower mobility (27.70% and 32.89%, respectively), with P1-2 pores as the dominant contributors. Pore structure complexity exhibits a significant nonlinear evolutionary relationship with fluid mobility. The fluid mobility index demonstrates a strong positive correlation with the degree of mobile fluid, validating its effectiveness in characterizing fluid mobility in deep coal rock reservoirs. These findings provide a theoretical foundation for sweet spot identification and development optimization in deep coal gas reservoirs. Full article

This preliminary within-animal study focuses on the comprehensive characterization of pork jowl (PJ) by comparing it with pork belly (PB), Boston butt (BB), and spare ribs (SR) collected from the same ten castrated Duroc × Landrace × Yorkshire (DLY) pigs; headspace volatile analysis used a matched subset of six pigs. Instrumental quality, proximate composition, amino-acid and fatty-acid profiles, low-field nuclear magnetic resonance (LF-NMR) water distribution and headspace solid-phase microextraction–gas chromatography–mass spectrometry (HS-SPME-GC-MS) volatile profiles were evaluated. PB exhibited the lowest shear force, hardness, and chewiness. Across the four pork cuts, crude protein content ranged from 16.87% to 18.10%, whereas crude fat content ranged from 13.03% to 22.20%. BB had the lowest crude fat content (13.03%) and relatively high protein (18.10%) and amino-acid contents. PJ showed highest content of monounsaturated fatty acids (MUFAs) and the lowest numerical atherogenic (AI) and thrombogenic indices (TI), but also the highest n-6/n-3 polyunsaturated fatty acids (PUFA) ratio. LF-NMR showed that PJ had the highest T₂₃ and P23 values, consistent with its higher cooking and centrifugal losses. Sixty-five headspace volatile compounds were tentatively identified under the standardized 80 °C HS-SPME conditions. OPLS-DA differentiated the four cuts, and ten compounds meeting the combined criteria of VIP > 1, q < 0.05, and OAV > 1 were retained as candidate discriminant aroma-relevant compounds. Overall, the four cuts exhibited distinct quality profiles: PJ combined a MUFA-rich lipid fraction with greater free-water mobility and water loss, PB showed the greatest instrumental tenderness, BB had the lowest crude fat content and relatively high protein and amino-acid contents, and SR exhibited the greatest headspace volatile abundance. The data provide a reference for cut-specific utilization of pork raw materials. Full article

Frozen seafood plays an important role in the global food supply, but maintaining its quality during frozen storage and cold-chain distribution remains a significant challenge. Although freezing effectively slows microbial growth and enzymatic activity, it cannot completely prevent quality deterioration. During frozen storage, seafood undergoes a series of interconnected physicochemical changes, including ice crystal growth, protein denaturation and oxidation, lipid oxidation, water redistribution, and texture deterioration. These changes gradually reduce sensory quality, nutritional value, and overall commercial acceptability. Conventional quality assessment methods, including destructive laboratory analyses and sensory evaluation, are still widely used. However, they are often labor-intensive, time-consuming, and unsuitable for rapid or real-time monitoring in modern cold-chain systems. As a result, increasing attention has been given to non-destructive sensing technologies that can evaluate seafood quality quickly and objectively. This review summarizes the major mechanisms responsible for quality deterioration in frozen seafood, together with recent advances in sensing technologies used to monitor these changes. The sensing approaches discussed include near-infrared (NIR) and Raman spectroscopy, hyperspectral and fluorescence imaging, low-field nuclear magnetic resonance (LF-NMR), electronic nose (E-nose), electronic tongue (E-tongue), colorimetric sensor arrays (CSAs), and biosensors. This review also discusses the growing role of artificial intelligence in frozen seafood quality assessment, including chemometrics, machine learning, deep learning, and multi-sensor data fusion. Particular attention is given to their applications in quality prediction, industrial implementation, and decision support. Finally, current challenges and future research needs are highlighted, with emphasis on the development of interpretable, transferable, and real-time monitoring systems that can support more reliable quality assurance throughout the frozen seafood supply chain. Full article

Reducing sodium in meat products is nutritionally desirable, but salt reduction often weakens myofibrillar protein gelation and reduces texture quality and water retention. This study investigated the effects of L-lysine (Lys) and konjac glucomannan (KGM) on the physicochemical properties, gel characteristics, and structural changes of beef myofibrillar protein (MP) gels under low-salt conditions. The results indicated that reducing NaCl from 0.6 to 0.2 M decreased water-holding capacity (WHC), increased cooking loss, and produced a loose gel network. Compared with the 0.2 M NaCl group, the combined Lys-KGM treatment increased WHC from 28.53% to 56.70% and reduced cooking loss to 22.19% (p < 0.05). Texture analysis showed that Lys-KGM increased hardness and springiness by 69.40% and 80.43%, respectively (p < 0.05). LF-NMR indicated a higher proportion of immobilized water and reduced water mobility in the combined treatment. Lys increased reactive sulfhydryl content and surface hydrophobicity, whereas KGM reduced surface hydrophobicity and enhanced water immobilization. Lys-KGM slightly but significantly decreased α-helix and increased β-sheet contents (p < 0.05), accompanied by changes in the relative contributions of intermolecular forces and a more continuous gel network. Molecular docking and molecular dynamics simulations provided supporting evidence for different interaction patterns between myosin and Lys/KGM. These results suggested that Lys and KGM might help maintain the quality of low-salt meat protein gels and provide a formulation basis for reduced-sodium meat products. Full article

Coal-based solid-waste binders provide a promising route for integrating mine backfilling with CO₂ mineralization, but auxiliary components can affect flowability, strength, and mineralization response differently. In this study, coal gasification slag (CGS) and ground granulated blast-furnace slag (GGBS) were used as the base binder, while soda residue, carbide slag, phosphogypsum, desulfurization gypsum, and red mud were introduced as functionally distinct auxiliary components. The binders were subjected to CO₂ injection mixing, and their flowability, compressive strength, apparent CO₂ uptake, reaction products, and pore-related characteristics were evaluated. The response to CO₂ treatment depended strongly on the auxiliary–component combination. CO₂ injection mixing reduced the early-age strength of most formulations. In contrast, the carbide slag–red mud formulation, CGS9, showed favorable compatibility between cementitious reactions and mineralization. Its 3 d and 7 d strengths increased by 36.0% and 14.4%, respectively, while its 28 d strength remained nearly unchanged. Its apparent CO₂ uptake and carbonation degree reached 3.825% and 13.46%, respectively. XRD showed stronger calcite diffraction peaks after CO₂ injection mixing, while FTIR showed enhanced carbonate absorption bands. SEM-EDS and LF-NMR indicated matrix densification and refinement of the water-filled pore environment. These findings show that functionally distinct auxiliary solid wastes can help coordinate cementitious reactions and CO₂ mineralization, providing a feasible route for producing low-carbon mine backfill materials from coal-based solid wastes. Full article

Prior studies on Ganoderma lucidum spore oil (GLSO) rarely systematically explored its storage oxidative deterioration mechanism via multi-marker combined characterization. This study innovatively integrated the Schaal oven accelerated storage test and dual-NMR detection (LF-NMR and ¹H NMR) to evaluate the oxidative stability of GLSO over 60 d. Dynamic changes in routine oxidation indices, glycerol core aldehydes (GCAs), phytosterols and their triterpenoid biosynthetic precursors, fatty acids and volatile compounds were synchronously tracked. Results revealed complex fluctuating accumulation of primary and secondary oxidation products; non-volatile GCAs exhibited continuous monotonic growth and acted as reliable markers for severe GLSO oxidation. Unsaturated fatty acids and phytosterols and their triterpenoid biosynthetic precursors degraded in a structure-dependent pattern, with phytosterols and their triterpenoid biosynthetic precursors degradation sensitivity ranked as squalene > lanosterol > β-sitosterol. Correlation analysis clarified the intrinsic linkage between fatty acid substrates and oxidation derivatives. This work innovatively reveals the complete lipid oxidation pathway of GLSO, offering novel theoretical references and multi-index evaluation strategies for quality control and preservation of high-grade GLSO products. Full article

The premature deterioration of reinforced concrete structures caused by steel reinforcement corrosion remains a major challenge to long-term structural durability. This study systematically investigates the effects of corrosion inhibitor dosage on the fresh properties, mechanical performance, chloride ion penetration resistance, and capillary water absorption of self-compacting concrete (SCC). The evolution of the pore structure is characterized using low-field nuclear magnetic resonance (LF-NMR) and X-ray computed tomography (X-CT), and the proportions of pores within different equivalent spherical diameter ranges are quantified. In addition, the microstructural characteristics are examined by scanning electron microscopy (SEM). The results show that the incorporation of the corrosion inhibitor increases the viscosity of fresh SCC, resulting in reductions in slump. In general, the corrosion inhibitor reduces both the compressive strength and splitting tensile strength of SCC, with the smallest strength reduction observed at a corrosion inhibitor dosage of 2 wt%. All mixtures containing the corrosion inhibitor exhibit lower electric flux and water absorption than the control mixture, indicating improved resistance to chloride ion penetration and capillary water ingress. The combined LF-NMR, X-CT, and SEM results indicate that an appropriate corrosion inhibitor dosage may optimize the spatial distribution of hydration products, refine the pore structure, reduce total porosity, and suppress the formation of macropores. Overall, a dosage of 2 wt% provides the most favorable balance among workability, mechanical properties, durability, and microstructural compactness. These findings provide experimental support and technical guidance for the mixture design of durable SCC used in aggressive environments, including marine and salt-lake regions. Full article

Retained water associated with water-locking can restrict gas production in heterogeneous tight sandstones, and the activity and phase stability of many surfactant treatments are reduced under high-temperature, high-salinity (HTHS) conditions. In this study, a composite surfactant formulation, CSF-1, designed to lower gas–brine capillary resistance and adjust sandstone wettability under representative reservoir constraints, is reported. Its performance was evaluated using thermal aging, surface tension and contact angle measurements, geochemical compatibility tests, laser diffraction, SEM/EDS, and core flooding combined with stagewise low-field nuclear magnetic resonance (LF-NMR). CSF-1 remained macroscopically homogeneous after aging at 170 °C in 188.314 g/L hypersaline brine and retained low gas–brine surface tension when measured at 25 °C after aging. In core flooding tests, CSF-1 increased the apparent gas permeability from 0.203 to 0.388 mD relative to the SFW-saturated water-locked state, corresponding to a 91.1% improvement. One- and two-dimensional NMR measurements provided comparative relaxation domain evidence that CSF-1 promoted the removal and redistribution of relatively mobile and weakly restricted fluid signals and reduced residual signal clustering. The shortest T₂ relaxation domains were less affected. The absence of replicate core flooding and associated LF-NMR runs, together with the non-equivalent Ref-S comparison, precludes a statistically rigorous cross-agent performance ranking. These results support the laboratory water-locking mitigation potential under the tested conditions, without implying calibrated pore-size-resolved removal or field-scale confirmation. Full article

Patients with muco-obstructive lung disease (MOLD) exhibit chronic bronchitis and inflammation, along with a progressive decline in lung function. Lung monitoring is typically performed using spirometry, especially by measuring the forced expired volume in the first second (FEV₁). However, the limitations of spirometry motivated the exploration of alternative approaches. The spin–spin relaxation time (T_2m) and the spin–lattice relaxation time (T_1m) of sputum water hydrogens were measured using low-field nuclear magnetic resonance (LF-NMR) in 38 MOLD patients and 16 controls. The levels of TNFα/IL-6, the sputum microbiome composition/amount/indices and FEV₁ were determined in parallel. We also investigated the correlation between T_2m/T_1m and the disease index (I_D); I_D, calculated relying on patient FEV₁/TNFα/IL-6/bacteria concentration C_b values, is a measure of the patient’s distance from the average healthy control. We observed the following significant correlations: T_2m/T_1m with I_D, T_2m with C_b, a potential correlation of T_2m with the bacteria genera Streptococcus and Staphylococcus, T_2m with the Shannon index, which reflects the broadness of the bacterial community in the sputum, and T_2m with TNFα. FEV₁ did not show any correlation. Our noninvasive/radiation-free/portable method of T_2m/T_1m measurement shows potential value in monitoring lung conditions in MOLD patients and may contribute to improved clinical decision-making. Full article

To address the issues of rough mouthfeel and monotonous flavor in plant-based beverages, this study used extruded millet flour as the raw material, with non-inoculated millet paste as the control group, and investigated the effects of six different lactic acid bacteria starter culture formulations—including two single strains (Streptococcus salivarius subsp. thermophilus and Lactobacillus delbrueckii subsp. bulgaricus) and four multi-strain consortia (2, 4, 10, and 12 strains)—on the quality of fermented millet beverages. The structural properties of the fermented millet beverages were systematically evaluated through WHC (Water Holding Capacity), LF-NMR (Low-Field Nuclear Magnetic Resonance), RVA (Rapid Visco Analyzer), rheological properties, texture, particle size, and FTIR (Fourier Transform Infrared) analyses, covering aspects such as water status, pasting behavior, viscoelasticity, textural characteristics, particle distribution, and molecular structure. In combination with volatile flavor profiling and sensory evaluation, the fermentation performance and applicability of each starter formulation were comprehensively assessed. The results showed that MFB-2 exhibited the highest viscosity and gel strength, making it suitable for thick-set products, whereas MFB-10 and MFB-12 demonstrated superior gel stability, water-holding capacity, and shelf life. Sensory evaluation further corroborated the flavor analysis, with MFB-12 showing the best aroma and overall acceptability, alongside the greatest diversity of volatile compounds, while MFB-10 presented milder acidity and favorable sensory acceptability. Collectively, MFB-10 and MFB-12 were identified as the most promising starter culture formulations for industrial-scale production of fermented millet beverages. This study provides a scientific basis for tailoring starter culture complexity to modulate the texture and flavor of plant-based fermented products. Full article

In response to the water loss, shrivelling, and oxidative ageing commonly observed in Golden passion fruit after harvest, this study systematically evaluated the regulatory effects of short-wave ultraviolet (UV-C) treatment. The results showed that UV-C treatment at 3.6 kJ m⁻² significantly curtailed the increases in weight loss and shrivelling index during storage. Low-field nuclear magnetic resonance (LF-NMR) analysis revealed that this treatment effectively maintained the stability of water distribution in fruit tissues by delaying the conversion of free water to bound water. Regarding antioxidant regulation, UV-C treatment significantly increased the activities of key antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR), while promoting the accumulation of non-enzymatic antioxidants, such as total phenols, total flavonoids, and ascorbic acid (AsA). These changes synergistically enhanced reactive oxygen species (ROS)-scavenging capacity, leading to significant reductions in H₂O₂ content and malondialdehyde (MDA) levels, thereby alleviating lipid peroxidation damage to cell membranes. Overall, UV-C treatment effectively maintained cell membrane integrity and regulated water migration through the coordinated regulation of enzymatic and non-enzymatic antioxidant defence systems, thereby delaying passion fruit shrivelling and improving postharvest quality and storage stability. Full article

Self-compacting concrete (SCC) is widely adopted in complex structural engineering due to its excellent flowability and filling capacity. However, in harsh corrosive environments, its complex internal pore structure can easily serve as a preferential pathway for the transport of aggressive media, leading to durability deterioration. This study systematically investigates the effects of chemical attack inhibitor (CAI) on the workability, mechanical properties, sulfate attack resistance, and chloride ion penetration resistance of SCC. The micro-mechanisms governing pore structure evolution are elucidated using low-field nuclear magnetic resonance (LF-NMR) and X-ray computed tomography (X-CT). At a CAI dosage of 2%, the fresh SCC exhibits a slump of 260 mm and slump flow of 720 mm, indicating excellent filling and gap-passing abilities. Meanwhile, the compressive strengths at 3 d, 7 d, and 28 d remain at a high level. After 120 sulfate wet-dry cycles, the strength loss rate is only 8.4%, with an erosion resistance coefficient exceeding 90%. In addition, the resistance to chloride ion penetration is significantly improved, with an electric flux of only 1331 C, which is considerably lower than that of the control group (1637 C). At the optimal dosage of CAI, the concrete exhibits a dense and uniform internal structure devoid of macroscopic defects or cracks, with minimized porosity, thus synergistically enhancing the resistance to sulfate attack and chloride attack. On the contrary, further increasing the CAI dosage markedly intensifies the inhibitory effect of organic components on cement hydration, leading to increased early-age defects and enhanced pore connectivity. Thus, an appropriate amount of CAI can effectively improve the overall performance of SCC, providing a solid experimental basis and theoretical support for its engineering application in harsh corrosive environments. Full article

Mashed potatoes (MP) are widely consumed starch-based foods. However, their shelf life is limited by starch retrogradation during low-temperature storage, which causes texture hardening, water exudation, and sensory deterioration. Although natural polysaccharides can modulate starch properties, the specific anti-retrogradation effect of soluble arabinoxylan (AX) in complex MP matrices remains unknown. In this study, the effects of AX on the physicochemical and sensory qualities of MP during 7 d of storage at 4 °C were comprehensively investigated. Results demonstrated that AX significantly reduced the rheological moduli (i.e., G′ and G″ values) and hardness of stored MP. Additionally, LF-NMR, XRD, FTIR and SEM analyses, together with water holding capacity (WHC) measurement, revealed that AX improved water retention and restricted water mobility of the system, delayed starch recrystallization, inhibited the formation of short-range ordered structures, and physically disrupted the starch microstructure, thereby attenuating the overall starch retrogradation process. Moreover, the addition of AX helped maintain the sensory appeal of the products. These findings suggest that AX modulates the structural evolution of the starch matrix during storage. This distinguishes the present work from conventional hydrocolloid studies by demonstrating that AX can simultaneously inhibit starch retrogradation, stabilize color, and maintain soft texture. This work highlights the potential of AX as a clean-label multifunctional modifier to extend the shelf life of starchy convenience foods. Full article

Understanding the spatiotemporal variability of nanoplastics (NPs) in porous media is vital for environmental risk assessment, yet quantitative in-media analysis of NP distributions during transport remains limited. To address this, we innovatively applied low-field nuclear magnetic resonance (LF-NMR) as a non-invasive approach to dynamically monitor magnetic polystyrene nanoplastic (MPSNP) transport in saturated quartz sand. By establishing the relationship between LF-NMR transverse relaxation rate [1/T_2,I − 1/T_2,0] and MPSNP concentrations, we reconstructed spatiotemporal concentration profiles via T₂ inversion. This methodology enabled systematic evaluation of the effects of ionic strength (IS), flow velocity, initial concentration, and flow direction. Three mathematical models were further applied to analyze MPSNP transport behavior. Results revealed IS as the dominant factor; increasing IS (0.001 to 1 mM) dropped mass recovery from 85.7% to 0%, the migration front no longer advanced at IS > 5 mM. Lower flow rates, higher initial concentrations, and horizontal flow also enhanced retention. The two types of two-site kinetic models provide a better fit for the features of the breakthrough curves. This novel use of LF-NMR demonstrates its robust capability to resolve spatial transport heterogeneity, underscoring that flow velocity, flow direction, and ionic strength are critical regulatory parameters that should be carefully accounted for when evaluating nanoplastic transport in porous media. Full article

This study investigated the effects of freeze–thaw pretreatment on the solar hot-air drying behavior, moisture migration, and microstructure of Mongolian Astragalus (Astragalus membranaceus var. mongholicus) slices. An L9 orthogonal design with slice thickness, diameter, air velocity, and drying temperature was used; drying kinetics, water-state distribution, and surface morphology were assessed by thin-layer models, apparent effective moisture diffusivity, LF-NMR, and SEM. The drying process showed no obvious constant-rate period and was mainly characterized by a falling-rate stage, indicating that dehydration was controlled by internal moisture migration. Freeze–thaw pretreatment redistributed the initial water fractions but did not uniformly accelerate drying; the longest drying time decreased from 130 to 100 min, showing a condition-dependent effect. Slice thickness was the dominant factor affecting the average drying rate. The preferred conditions were 1–3 mm thickness, 8–11 mm diameter, 1.0 m·s⁻¹ air velocity, and 50 °C for the control group, and 1–3 mm thickness, 11–14 mm diameter, 1.5 m·s⁻¹ air velocity, and 50 °C after freeze–thaw pretreatment. The Midilli model best fit the moisture-ratio data, and the apparent effective moisture diffusivity remained on the order of 10⁻⁹ m²·s⁻¹. LF-NMR showed that endpoint residual moisture was mainly bound water, with free water almost completely removed. SEM observations showed a looser surface with more visible pores and cracks after freeze–thaw pretreatment. Overall, freeze–thaw pretreatment mainly affected solar hot-air drying by regulating moisture migration, with effects depending on process conditions. Full article