Search Results (1,126)

Mean atomic bond strain (MABS), based on the globally averaged bond length, has recently emerged as a new strain metric that retains clear physical meaning even as severe atomic neighborhood reconstruction occurs. It has been shown to exhibit a nearly perfect linear relationship with global stress throughout the elastic and plastic deformation in single-crystal face-centered cubic (FCC) metals, contradicting conventional expectations based on nonlinear dislocation activity. Whether this near-linear relationship holds in other materials stands out as an important and intriguing question. In this study, we examine the MABS–stress relationship in representative unary, binary, and ternary metallic glasses (MGs), where neither a crystal structure nor dislocations are present. Large-scale molecular dynamics simulations of uniaxial tensile tests and statistical analysis of millions of atomic bonds are performed. Irrespective of their differing compositions, all the MGs exhibit a persistent near-linear relationship between total MABS (all bonds included) and global stress up to fracture, even in the presence of significant local nonaffine displacements (shear transformation zones and shear bands), with the Pearson correlation coefficient consistently exceeding 0.99. Unlike the nonaffine displacements, the spatial distribution of individual atomic bond strain does not localize under the uniaxial loading. In the MGs containing more than one element, MABS computed for a single bond type may not correlate as linearly with global stress as total MABS. The results demonstrate that the persistent near-linear total MABS–stress relationship over the entire deformation process, recently discovered in single-crystal FCC metals, also applies to MGs despite their vastly different atomic structures. This strengthens the candidacy of total MABS as a universal stress descriptor across materials classes and deformation regimes. With further development and implementation in atomistic simulations and constitutive modeling, the MABS concept has the potential to reshape our understanding of materials mechanics and generate new insights into the design of stronger, tougher, and more thermally and chemically stable materials. Full article

Background/Objectives: Differentiating focal nodular hyperplasia (FNH) from hepatic adenoma (HA) remains challenging, as FNH is benign whereas HA carries risks of hemorrhage and malignant transformation. This prospective single-center pilot study evaluated the diagnostic performance of three-dimensional magnetic resonance elastography (3D-MRE) using a gravitational transducer for non-invasive differentiation of FNH and HA. Methods: Thirty-three participants (23 FNH, 10 HA) underwent 3D-MRE using the gravitational transducer. Viscoelastic parameters—stiffness, shear wave speed (Cs), wave attenuation, and phase angle—were quantified for lesions and background parenchyma. $\Delta$-values were calculated by subtracting background liver measurements from lesion values. Results: FNH demonstrated significantly higher stiffness than HA (median 3.16 vs. 2.58 kPa; p = 0.02) and higher Cs (median 1.81 vs. 1.64 m/s; p = 0.001). Normalized stiffness differences ($\Delta$ stiffness) were significantly greater in FNH than HA (median 0.83 vs. 0.10 kPa; p = 0.001). Generalized additive models revealed divergent volume-dependent stiffening behaviors. In ROC analysis, $\Delta$ stiffness and $\Delta$ Cs each achieved an AUC of 0.87, indicating that single background-normalized viscoelastic parameters carry the principal diagnostic signal. An exploratory multivariable combination of $\Delta$ stiffness with patient age produced an apparent AUC of 0.93 with wide odds-ratio confidence intervals, and is presented as hypothesis-generating rather than as a clinical prediction model. Conclusions: In this pilot cohort, 3D-MRE using the gravitational transducer showed encouraging parameter-level separation between FNH and HA, with background normalization enhancing discrimination. Wave attenuation and phase angle did not differ significantly between lesion types. Given the small sample size (particularly the HA subgroup of ten patients), the mixed reference standard (histological confirmation in only 14 of 33 lesions; definitive hepatobiliary-phase MRI criteria in 19 of 33), the single-slice ROI used for lesion measurement, and the incomplete characterization of background liver parenchyma, these findings should be regarded as hypothesis-generating and require external validation in larger, multicenter cohorts before any clinical application. Full article

To address the challenges of bedding separation and large deformation in deep gob-side roadways with composite roofs under the influence of stress deviation and weak interlayers, this study takes the 1692(1) rail roadway of Pansan Coal Mine as the research object. By combining numerical simulation, theoretical analysis, and field testing, the study thoroughly investigates the evolution patterns of the plastic zone in the surrounding rock and the mechanisms governing delamination. The results demonstrated that stress deviation induces shear failure of weak interlayers and causes bedding separation at the early excavation stage, which subsequently transforms into tensile failure and leads to coal pillar instability. The principal stress deviation angle determines the expansion direction of the plastic zone, while the thickness and number of weak interlayers are positively correlated with the degree of bedding separation. It is concluded that the coal pillar strength is a critical factor for bedding separation control. Based on these findings, a combined control scheme of “strengthening coal pillars, restraining shear damage, improving coordinated deformation” is proposed. Field engineering practice confirms that this proposed scheme effectively restrains the expansion of the plastic zone and ensures the long-term stability of the roadway. Full article

Accurate prediction of Rate of Penetration (ROP) in carbonate formations remains constrained by the arbitrary selection of geomechanical input parameters in empirical drilling models. This study presents the first systematic field-based evaluation of sixteen geomechanical properties—grouped into three categories: strength parameters (uniaxial compressive strength (UCS), confined compressive strength (CCS), shear strength, thick-walled cylinder strength (TWC), friction angle, and cohesion), elastic moduli (Young’s modulus, shear modulus, bulk modulus, bulk compressibility, dynamic combined modulus (DCM), Poisson’s ratio, brittleness index), and in situ stress parameters (overburden pressure, minimum, and maximum horizontal stresses)—to identify optimal predictors for ROP modeling across PDC bit sizes of 12.25″ and 8.5″. Continuous wireline log data from two vertical carbonate wells in the Middle East (Well A: 1000–3370 m; Well B: 1945 to 3128 m; total intervals of 2370 m and 1183 m, respectively) penetrating formations comprising limestone, dolomite, sandstone, shale, anhydrite, and marly limestone were used. All sixteen geomechanical properties were computed using Interactive Petrophysics (IP) software with lithology-specific empirical correlations and validated against laboratory core measurements (R² = 0.79–0.95). Pearson and Spearman correlation analyses quantified parameter–ROP relationships, and the Al-Abduljabbar empirical model, recalibrated via multiple nonlinear regression, served as the evaluation framework. DCM consistently exhibited the strongest negative correlation with ROP across both bit sizes and achieved the highest model accuracy (R² = 0.54, AAPE = 25.33%), significantly outperforming the Bourgoyne and Young model (R² = 0.26, AAPE = 36.55%). A statistically validated scale-dependent effect was identified: Fisher’s Z-transformation tests confirmed that the correlation reversal between CCS and UCS across bit sizes is statistically significant (CCS: Z = −16.84, p < 0.001; UCS: Z = −6.75, p < 0.001), establishing CCS as the superior predictor at 12.25″ and UCS as the superior predictor at 8.5″—a finding not previously reported in the ROP literature. This reversal is attributed to the larger contact area of the 12.25″ bit, which promotes confinement-dominated rock failure better described by CCS, whereas the smaller bit produces localized stress concentration better represented by UCS. These results establish that (1) optimal geomechanical input selection is bit-size dependent, (2) nonlinear modeling outperforms linear frameworks for strength–ROP relationships, and (3) parameter relevance outweighs coefficient tuning in model robustness. DCM is recommended as the most operationally practical universal input, requiring only conventional compressional sonic and density logs. This study provides a systematic framework for geomechanical parameter selection with direct implications for drilling optimization in heterogeneous carbonate reservoirs. Full article

The crystal structure evolution and phase transformation of single-crystal germanium during temperature-assisted nanomachining were investigated using the molecular dynamics method. The differences in surface atomic distribution, material removal volume, subsurface damage depth, surface roughness, and normal cutting force of single-crystal germanium under two different cutting depths at preheating temperatures of 300 K, 450 K, 600 K, 750 K, and 900 K were compared. The results show that with the increase in cutting depth, the material removal amount and subsurface damage depth increase. In addition, as the temperature increases, the thermal softening effect mitigates brittle fracture at low temperatures can reduce the brittle fracture at low temperatures, and the material removal mode also transitions from brittle fracture to plastic shear, which makes the internal stress of the workpiece balanced and thus conducive to forming a better machined surface. However, constrained by the size effect, it is difficult to explain the machining mechanism of single-crystal germanium cutting at the macroscopic level. Therefore, this study innovatively simulated the heating input via temperature control, revealing the machining mechanism of single-crystal germanium cutting at different temperatures from a microscopic perspective. The results show that increasing cutting depth enlarges material removal volume and subsurface damage. More importantly, preheating induces a non-monotonic transition in material removal behavior: from brittle fracture at 300 K to stable plastic shear between 450 K and 750 K, and eventually to thermally induced tearing above 750 K. An optimal processing window is identified—450 K minimizes subsurface damage, while 750 K maximizes removal efficiency. These findings provide quantitative guidance for selecting preheating temperatures in ultra-precision machining of brittle semiconductors. Full article

The pursuit of lightweight, high-performance sports equipment drives the development of Al-Li-Mg alloys, yet systematic studies linking a complete processing route, from as-cast to peak-aged condition, to microstructural evolution and mechanical properties remain limited. This work provides the first comprehensive investigation of how a sequential processing route (homogenization, hot rolling, solution treatment, and peak aging) transforms the coarse as-cast structure of an Al-Li-Mg alloy into a refined, recrystallized grain architecture with a uniform dispersion of nanoscale δ′-Al₃Li precipitates. This microstructural transformation leads to a dramatic enhancement in mechanical properties: the peak-aged alloy exhibits increases of approximately 92%, 139%, and 925% in yield strength, ultimate tensile strength, and elongation, respectively, relative to the as-cast condition. The dominant strengthening mechanism is identified as dislocation shearing of coherent δ′-Al₃Li precipitates (average radius ~5 nm, well below the ~25 nm transition threshold for Orowan looping), which enhances strength without compromising ductility, demonstrating the critical role of the processing route in tailoring microstructures and mechanical properties for lightweight sports equipment. Full article

The model is based on the periodic translational symmetry of regular saw-toothed joint surfaces and reveals the time-dependent breaking of this symmetry under hydro-mechanical coupling through the introduction of damage evolution. Traditional creep models typically rely on static constants, which fail to capture the nonlinear, time-dependent degradation of rock under complex conditions. To address this, this paper proposes a novel nonlinear shear creep model for regular saw-toothed joint surfaces under hydro-mechanical coupling. First, a calculation method for effective shear stress is established, accounting for normal stress, asperity height, and water pressure. Next, traditional static parameters are transformed into dynamic variables to accurately model the primary and steady-state creep stages. Finally, a plastic damage element is introduced to simulate the accelerated creep stage, revealing that damage accumulates with time and is exacerbated by higher seepage pressure. By integrating early-stage viscoelastic and late-stage viscoplastic characteristics, this model captures the complete nonlinear shear creep process, providing a robust theoretical basis for long-term stability evaluations. Full article

Shallow shear-wave velocity structures provide useful constraints on sedimentary architecture in coastal abandoned-estuary settings, yet laterally continuous velocity information remains limited in the Paleo-Yellow River Estuary, Yancheng, Eastern China. In this study, vertical-component ambient noise recorded by a dense linear array of 102 short-period stations over 27 days was used to derive Rayleigh-wave phase-velocity dispersion curves by the modified frequency-Bessel (MFJ) method. Sequential 1D S-wave velocity models were inverted beneath moving subarrays and interpolated to construct a pseudo-2D velocity profile along the survey line. For comparison, the conventional spatial autocorrelation (SPAC) method was applied to the same dataset using the same subarray length, usable frequency band, and inversion-layer parameterization. The MFJ method produces clearer and more concentrated fundamental-mode dispersion energy and suppresses high-frequency crossed artefacts more effectively than SPAC, which improves the stability of dispersion picking. The resulting velocity model reveals a laterally heterogeneous shallow sedimentary system and outlines a U-shaped low-velocity zone that is spatially consistent with the mapped paleochannel boundary. These results indicate that MFJ-based ambient-noise imaging can provide useful complementary geophysical constraints for paleochannel mapping and shallow sedimentary characterization in coastal abandoned-estuary settings. Full article

To enhance the overall performance of direct coal liquefaction residue (DCLR)-modified asphalt, particularly its low-temperature cracking resistance, SBS and aromatic oil were employed for composite modification. Nine composite-modified asphalt formulations were prepared based on an orthogonal experimental design. High-and low-temperature rheological properties and microstructure of all modified asphalts were systematically evaluated using a dynamic shear rheometer (DSR), a bending beam rheometer (BBR), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The results indicate that composite modification significantly enhanced the high-temperature performance of the asphalt. Modified asphalt labeled as Sample No. 9 (9% DCLR, 4% SBS, and 6% aromatic oil) demonstrated the minimal non-recoverable creep compliance ($J_{nr}$) value of 0.58 kPa⁻¹ at 64 °C, indicating a 78.6% decrease relative to the matrix asphalt. In terms of low-temperature performance, Sample No. 3 satisfied the Superpave cracking resistance criterion, exhibiting a creep rate ($m$-value) of 0.312 at −12 °C. It was revealed by FTIR analysis that the interaction between the composite modifier and the base asphalt was mainly physical blending, and no new functional groups were generated either before or after aging. The improvement in performance was attributed to the physical compatibility and structural reorganization among the components. Microstructural analysis revealed that the uniform dispersion of modifiers in matrix asphalt and the subsequent formation of a dense micelle structure after aging contributed to the enhanced macroscopic performance. This study provides theoretical and technical support for the high-value application of DCLR in asphalt pavements. Full article

In this paper, the elastic precompression method is employed as a pretreatment technique to investigate the evolution and characteristics of the micro-mechanical properties of metallic glasses. Nanoindentation analysis indicates that pre-compression treatment leads to structural rearrangement within the material, which in turn influences the nucleation and propagation of shear bands, resulting in a transition of serrated flow from a step-like to a wave-like pattern under a 400 MPa load held for 75 min. Crucially, precompression triggers a unique “decoupling” response: hardening alongside elastic softening. Further, this structural evolution is evidenced by the shear transition zone volume calculated using the jump rate method. The shear transition zone volume exhibits a nonlinear trend, initially increasing and then decreasing with increasing compressive strength and holding time, which reflects the kinetic competition mechanism between local shear instability and coordinated atomic rearrangement that arises under precompression. This study elucidates the effect of elastic precompression treatment on the micromechanical properties of a Ti-based metallic glasses, providing a reference for the optimization of plasticity in metallic glasses. Full article

To reveal the long-term anti-aging mechanisms of rubber–plastic elastomer-modified asphalt in complex service environments and overcome the inherent defects of single polymer modifiers—namely their susceptibility to degradation or phase separation—this study prepared styrene-butadiene-styrene (SBS), low Mooney rubber (LMMR), and low-density polyethylene (LDPE)-modified asphalts. Simultaneously, an LMMR-LDPE rubber–plastic thermoplastic elastomer (TPE) was fabricated utilizing twin-screw extrusion technology and subsequently used to prepare a composite-modified asphalt. Three aging protocols were simulated: short-term thermo-oxidative aging (RTFOT), long-term pressure aging (PAV), and ultraviolet light aging (UV). A multi-scale quantitative characterization was conducted using a dynamic shear rheometer, Fourier transform infrared spectroscopy, and atomic force microscopy to evaluate the rutting factor, carbonyl index, and surface microroughness of each system before and after aging. The experimental results indicate that the coupled effect of long-term stress and thermal oxidation causes the most severe damage to the colloidal structure of modified asphalt. Conventional SBS-modified asphalt, due to its abundance of unsaturated double bonds, exhibits a sharp increase in the carbonyl index and aging index of the rutting factor after aging, making it highly susceptible to oxidative chain scission. Although LDPE-modified asphalt possesses chemical inertness, it is prone to crystalline phase separation under aging conditions, resulting in a microroughness distortion rate of up to 86.36%. In contrast, the LMMR-LDPE composite system, leveraging the high chemical stability of the saturated aliphatic carbon chain and the flexibility-enhancing and crystallization-inhibiting effects of LMMR, effectively reduces active oxidation sites and improves interfacial compatibility. This composite system exhibits the lowest carbonyl increment and rheological attenuation under all aging conditions, while effectively inhibiting the free migration and agglomeration of macromolecular components. The LMMR-LDPE composite modification technology effectively overcomes the inherent drawbacks of single polymers, such as susceptibility to degradation or segregation, demonstrating excellent long-term macroscopic rheological stability and microscopic phase morphology anti-aging capability. The present findings provide laboratory-scale mechanistic support for the design of durable rubber–plastic-modified asphalt systems, while further pilot-scale, economic, and field validation is still required before practical engineering application can be fully assessed. Full article

Chia seed mucilage (CSM) is a promising plant-derived hydrocolloid characterized by unique physicochemical and functional properties that are strongly influenced by the extraction methodology. In this research, an optimized sonication–freezing-assisted extraction (SFAE) process was developed to obtain mucilage while preserving its structural integrity. Results indicate that the extracted mucilage has a high total dietary fiber content of 75.87% and a moderate protein level of 8.71%. Fourier transform infrared spectroscopy (FTIR) confirmed the presence of hydroxyl and ionized carboxylate (COO⁻) groups associated with uronic acids, highlighting the anionic and polyelectrolyte nature of the system. Rheological characterization of optimized-CSM revealed Newtonian behavior in dilute solutions, indicating minimal intermolecular interactions and permitting accurate measurement of intrinsic viscosity and viscosity-average molecular weight. A critical overlap concentration (c** ≈ 0.2% w/v) was identified, marking the transition to semi-dilute regimes, chain entanglement, and the onset of shear-thinning and viscoplastic behavior. Functionally, the optimized-CSM exhibited high water holding capacity and competitive emulsifying properties (emulsion activity index (EAI): 62.50%; emulsion stability index (ESI): 49.32%), attributed to synergistic interactions between proteins and polysaccharides. Overall, this work provides new insights into how processing conditions influence the chemical composition and molecular structure, which fundamentally govern the rheological and functional performance of CSM. These findings underscore its potential as a versatile hydrocolloid for food and biomedical applications. Full article

Riverbed dynamics and erosion processes remain an important research issue, particularly under increasing anthropogenic pressure on river systems. This study investigates long-term channel changes and bed-incision processes in selected Carpathian rivers—the Skawa, Raba, and Dunajec—with particular emphasis on bridge-affected reaches. The analysis combined hydrological and geomorphological data with one-dimensional MIKE 11 hydraulic modelling to assess local changes in flow parameters and indicators of erosion potential under Q1% flow conditions. In the analysed cross-sections, riverbed lowering ranged from 1.0 to more than 3.5 m over the observation period, confirming the occurrence of long-term channel degradation. The results indicate that this process was primarily related to historical gravel extraction and channel regulation, whereas bridges mainly modified local hydraulic conditions. In the vicinity of bridge structures, flow velocity increased to as much as 7.31 m/s, and local changes in water surface elevation reached 0.90 m, indicating increased susceptibility to local scour near piers and abutments. The modelling also showed marked local increases in bed shear stress. At the same time, the results do not support the conclusion that bridges are the primary cause of systemic erosion at the scale of entire river reaches. This research contributes to sustainable development because it provides the knowledge needed for better management of rivers and bridge infrastructure in a way that is environmentally, socially, and economically safe: it shows that long-term riverbed degradation results mainly from earlier anthropogenic transformations, such as aggregate extraction and river regulation, while bridges primarily alter local flow conditions and may increase the risk of erosion around piers and abutments. Full article

Heat-assisted metal spinning comprises incremental forming routes, conventional spinning, shear spinning and flow forming, performed at elevated temperature to increase formability. This review consolidates the main advances of the last fifteen years. It outlines spinning mechanics and the rationale for heating (higher ductility, lower forming forces and microstructure control), then compares global and local heating strategies (furnace, flame, induction, laser and hot-gas convection) in terms of temperature uniformity, industrial practicality, energy efficiency and cost. Key process parameters (spindle speed, feed rate and thickness reduction) are discussed with respect to defect formation, and representative windows for defect mitigation are reported. Progress in modeling is reviewed, including coupled thermo-mechanical finite element simulations, damage/formability prediction and emerging data-driven optimization. The review also summarizes microstructural evolution under heat-assisted conditions, phase transformation, dynamic recrystallisation and grain growth, and its impact on final properties. Across more than 100 studies, evidence shows that robust thermal management can roughly double achievable deformation before failure and enables property tailoring in difficult-to-form alloys (Ni-based alloys, high-strength steels, Al, Mg and Ti). Remaining challenges include reliable in situ temperature measurement/control and improved predictive fidelity of simulations. Future opportunities include digital twins, real-time sensing and adaptive, machine-learning-assisted control. Full article

Background/Objectives: Poor aqueous solubility limits the oral absorption and bioavailability of many active pharmaceutical ingredients. Simple formulation approaches suitable for hospital and community pharmacy compounding are therefore needed. This study aimed to develop and evaluate melt-filled hard capsules containing nifedipine, a model of poorly water-soluble BCS class II drug, using polyethylene glycol (PEG) carriers to improve dissolution performance. Methods: PEG blends of different molecular weights (PEG 400, PEG 1500, and PEG 4000) were prepared by melt mixing, followed by incorporation of nifedipine and manual filling into hard gelatin capsules. The formulations were characterized regarding mass variation, drug content, in vitro dissolution, rheological behavior, and solid-state properties using Fourier transform infrared (FTIR) spectroscopy. Dissolution profiles were kinetically modeled and compared with pure nifedipine. Results: All capsules met pharmacopoeial requirements for mass uniformity and showed acceptable drug content. PEG-based melt-filled formulations exhibited markedly enhanced dissolution compared with crystalline nifedipine. Faster drug release was associated with lower-molecular-weight PEGs and reduced viscosity, with the PEG 400/PEG 1500 blend demonstrating the most rapid dissolution. Rheological analysis confirmed shear-thinning behavior, while FTIR findings suggested intermolecular interactions and partial amorphization of nifedipine within the PEG matrices. Conclusions: This study provides a translational adaptation of solid dispersion principles into a compounding-compatible melt-filling approach. Full article