Geomechanica (Canada)

The pore network system, defined by Pore Size Distribution (PSD), geometry, and connectivity, plays a crucial role in controlling the storage and transport behavior of shale gas. Despite extensive investigations of shale formations across various Indian basins, pore characterization studies in the Lesser Himalaya remain largely unexplored. In particular, the Neoproterozoic Krol shale from the northwestern Lesser Himalaya represents one of the untapped units with promising gas-bearing characteristics. In this study, shale samples from the Krol Formation were systematically analyzed for pore characteristics across nano- to macro-scales using a combination of Low-Pressure Gas Adsorption (LPGA) with N2 and CO2, Small-Angle X-ray Scattering (SAXS), Field Emission Scanning Electron Microscopy (FE-SEM), and Micro-Computed Tomography (Micro-CT). LPGA N2 adsorption exhibited Type IIB isotherms with H3 hysteresis loops, indicating slit- and wedge-shaped mesopores, while CO2 adsorption revealed Type I isotherms, reflecting micropore filling. PSD derived from LPGA showed bimodal and multimodal patterns using Barrett–Joyner–Halenda (BJH) and Density Functional Theory (DFT) models, respectively. SAXS, sensitive to both open and closed pores, effectively captured the PSD, and the Porod–Debye Scattering Profile (PDSP) model confirmed the dominance of mesopores. FE-SEM observations revealed irregular to elongated nanopores (37–54 nm) and a moderately complex pore structure, as supported by fractal dimensions derived from LPGA, SAXS, and FE-SEM. Micro-CT analysis further indicated the presence of macropores and fractures (≥103 nm), with a mean Feret diameter of 0.07 mm and a pore volume of 0.02 mm3. Porosity values estimated from SAXS, FE-SEM, and micro-CT were 4.98%, 5.64%, and 4.55%, respectively. This integrated multiscale characterization, bridging nano to macroscale pore systems, provides new insights into the storage and transport behavior of gas and emphasizes the Krol shale as a future shale gas formation in the Lesser Himalaya.

Autism Spectrum Disorder (ASD) is a neurodevelopmental condition characterized by impairments in social communication, reciprocity, and adaptive behavior. Converging neurobiological evidence suggests that these clinical features arise from aberrant connectivity and dysregulated neuronal oscillations across distributed brain networks. In particular, dysfunction within the mirror neuron regions, concentrated in the inferior frontal gyrus (IFG) and inferior parietal lobule (IPL), has been implicated in deficits of imitation, empathy, and social cognition in ASD. Non-invasive neuromodulation using repetitive transcranial magnetic stimulation (rTMS) has shown modest behavioral benefits in ASD. However, most studies apply the conventional protocols targeting the dorsolateral prefrontal cortex. The effects of intermittent theta-burst stimulation (iTBS), a potent excitatory rTMS protocol targeting the mirror neuron regions, on the oscillatory dynamics in ASD remain largely unexplored. To investigate whether iTBS targeting the bilateral IFG and IPL modulates EEG-derived oscillatory activity in adolescents with ASD and to explore the relationship between oscillatory changes and social reciprocity. Six adolescents with Level I or II ASD (ages 13-18) underwent bilateral iTBS targeting the IFG and IPL using a figure-of-eight coil and standardized theta-burst parameters. Participants were randomized to receive either 18 active iTBS sessions or a waitlist-controlled crossover design (9 sham followed by 9 active sessions). Standard 21-channel EEG recordings were obtained during the first (EEG-1) and final (EEG-2) active stimulation sessions, including pre- and post-stimulation epochs. Power spectral analyses were conducted across frequency bands (delta through gamma). Behavioral outcomes were assessed using the Childhood Autism Rating Scale, Second Edition (CARS2), administered pre- and post-intervention. All participants tolerated the intervention without adverse effects. Behavioral analysis demonstrated a significant reduction in CARS2 scores following iTBS and is reported in detail in our prior clinical outcomes manuscript, consistent with improved social reciprocity (p < 0.001). EEG analysis revealed an immediate post-stimulation increase in gamma-band power during EEG-1 in five of six participants, whereas lower-frequency bands exhibited variable responses. In contrast, EEG-2 showed no consistent post-stimulation gamma enhancement. Net comparisons between EEG-1 and EEG-2 demonstrated attenuation of the initial gamma response in the same five participants. At the group level, gamma percent change did not reach statistical significance at EEG-1 (p = 0.12) or EEG-2 (p = 0.66), and exploratory comparisons between the 9-active versus 18-active arms did not reach statistical significance. While ipsi-directional changes in gamma power and CARS2 scores were observed in four participants, correlation was not identified in this pilot sample. Bilateral iTBS targeting the IFG and IPL induces a transient enhancement of gamma oscillations in adolescents with ASD that attenuates with repeated stimulation. This pattern is consistent with adaptive homeostatic plasticity (metaplasticity) within excitatory-inhibitory circuits, potentially mediated by GABAergic interneurons. These findings support the feasibility of EEG as an objective biomarker of neuromodulatory engagement in ASD and highlight the importance of network-level and oscillatory mechanisms in interpreting therapeutic responses. Larger, sham-controlled studies incorporating multimodal biomarkers are warranted to clarify clinical relevance and optimize personalized neuromodulation strategies.

The acid production reaction between CO2 and water in rocks changes the pore structure, thereby altering the rock mechanical properties. To ensure the safety of CO2 storage, it is critical to identify the rock damage mechanisms, clarify the variation patterns of mechanical properties under damage conditions, and investigate the flow characteristics of two-phase CO2-water systems under complex mixed-wettability. This study established a constant-temperature and -pressure multiphase CO2-rock immersion experimental system. Additionally, a comprehensive experimental procedure integrating CO2 immersion, CT imaging, and uniaxial compression was designed. A comparative study revealed that reactions involving gaseous CO2 and ScCO2 with water increased the core porosity by 1.2% and 2.9%, respectively. During the immersion period, gaseous CO2 accumulated on the upper section of the rock, causing a sharp increase in the surface porosity of the upper section (Δϕ = 0.9%). By contrast, ScCO2 accumulated on the middle section, causing a substantial increase in the surface porosity of the middle part (Δϕ = 2.8%). After the CO2 saturation in different phase states, the pore connectivity of the core was enhanced. When exposed to gaseous CO2, some isolated micropores became interconnected, thereby increasing connected porosity from 13.0 to 13.9%. When exposed to ScCO2, the connected porosity increased from 11.3 to 11.7%. Under damage conditions, the primary factors contributing to the deterioration of mechanical properties were the expansion of the pore volume and the increase in the number of connected pores. Compared to gaseous CO2, ScCO2 generated stronger carbonic acid upon reaction with water. After the acidification reaction, the number of both interconnected and isolated pores within the core increased, leading to considerable changes in the mechanical properties. Specifically, the compressive strength and elastic modulus decreased by 19.08 and 16.2%, respectively, and the Poisson’s ratio increased by 26.9%. Under the single-phase wettability, the displacement efficiencies of gaseous CO2 and ScCO2 were enhanced under weak and strong wettability conditions, respectively. The displacement efficiencies of gaseous CO2 and ScCO2 under complex mixed-wettability decreased by 5.7 and 15.3%, respectively, compared with those observed under single-phase wettability. Therefore, neglecting the complex mixed-wettability of pore wall surface often leads to the overestimation of displacement efficiency.

Summary Germany’s site selection procedure for a repository for high-level radioactive waste involves several phases, with detailed surface exploration of potential siting regions expected to start in 2031. Suitable host rocks include rock salt, claystone, and crystalline rocks. To prepare for the exploration phase, the GeoMetEr research project, funded by the Federal Company for Radioactive Waste Disposal (BGE), is evaluating and improving geophysical methods and their combinations. Research is conducted in two regions already excluded from the selection procedure: At Langenweißbach (Saxony) the project targets a crystalline rock, while at Harsefeld (Lower Saxony), the focus is on the overburden of a salt dome. In the first phase, a wide range of airborne, surface-based, and borehole geophysical methods - such as seismic surveys, semi-airborne electromagnetics, and magnetic measurements - are applied to image geological structures and rock properties. In the second phase, results will be verified through research drillings and borehole testing. GeoMetEr is carried out by nine partners from universities, non-academic research institutions, and industry. The project emphasizes joint interpretation of diverse datasets and the development of inversion strategies to build integrated 3D geological and parameter models, including an assessment whether the collected data meet repository site evaluation criteria.

Portable near‐infrared spectroscopy (NIRS) provides a noninvasive measure of local muscle metabolic demand through muscle oxygen saturation (SmO2). This study aimed to evaluate acute SmO2 responses in exercising and non‐exercising muscles during an isometric test conducted before and after exercise. Twelve physically active men (25 ± 6 years; 1.75 ± 0.07 m) performed three maximal voluntary contractions (MVC) and a 45‐s isometric contraction at 70% MVC (IC70%) before and after completing five sets of 30 concentric knee extensions at 180°·s−1, with 60 s rest between sets, on an isokinetic dynamometer. SmO2 was recorded in the vastus lateralis (exercised and non‐exercised leg) and triceps brachii. Significant differences in SmO2 were observed between exercised and non‐exercised legs both pre‐ (p = 0.048) and post‐exercise (p < 0.001), whereas no significant changes were found in the triceps brachii or non‐exercising vastus lateralis. Acute responses to isometric exercise differed between SmO2 and torque measures. While the torque of the IC70% did not change following the exercise protocol, SmO2 showed a higher deoxygenation response during exercise. The isometric test did not indicate any redistribution of muscle oxygenation from non‐exercising to exercising muscles. These results provide novel insights into the dissociation between mechanical and microvascular responses during isometric exercise and support the potential of this test as a practical tool for monitoring training loads.

Accurate static elastic properties are essential for reliable geomechanical modeling. However, dynamic log measurements are often compromised by the ‘gas effect’, which lowers dynamic moduli and introduces uncertainty. This study evaluates the true impact of fluid saturation on both static and dynamic elastic properties, using matched dry and mineral oil saturated sample pairs from five representative lithologies (Indiana Limestone, Austin Chalk, Berea Sandstone, Berea Buff Sandstone and Nugget Sandstone). Experimental procedures included cycled triaxial compression tests and ultrasonic velocity measurements. Results show a clear frequency-dependent divergence, with dynamic Young's modulus averaging 1.83 (dry) to 1.97 (saturated) times greater than its static counterpart. Critically, static Young’s modulus and peak strength exhibited negligible variation (less than 1.2%) between dry and saturated conditions using mineral oil, confirming that fluid saturation does not affect the intrinsic static properties of the rock. The Gassmann model’s assumption of fluid-independence for the shear modulus held for most lithologies (difference below 3%), supporting its routine application for log-to-core fluid substitutions. However, caution is advised for formations with complex mineralogy with Berea Sandstone showing a significant Gassmann error of –11.6%, and Austin Chalk of –5.1%. These findings provide the first direct experimental evidence that the apparent 'gas effect' is dynamic and not static and which affirmed fluid substitution as a necessary, standard procedure in geomechanical workflows.

The coal reservoir characteristics are mainly affected by pore structures and, therefore, influence safe exploration and development of coal and coalbed methane (CBM) resources. The pore size distribution and structure parameters of coals measured by traditional mercury intrusion porosimetry (MIP) experiments are much more accurate for big pores, while they are erroneous for small pores due to high mercury pressure. Therefore, this paper proposes a corrected method for pore size distribution and structure parameters using comprehensive measurements of MIP and low-temperature liquid nitrogen adsorption (LTLNA) for six high-rank anthracite coal samples. The pore size distributions obtained by two measurements in the range of 1–100 nm exhibit similar trends, and the developed pores in sizes of about 5, 50, and 100 nm coincide roughly. A ratio is introduced in this paper to match the developments of small pores measured by MIP and LTLNA. A corrected percentage is introduced as well to adjust the measurement deviation caused by MIP. After correction, the porosity for six samples varies from 4.17 to 13.97%, with an average of 6.29%. The average volumetric percentages for micropores, mesopores, and macropores are 17.24%, 20.05%, and 62.72%, respectively. A higher corrected percentage brings a lower deviation, resulting in more accurate measurement results by MIP. Therefore, it is much more accurate for MIP measurements under conditions of a larger average radius, low vitrinite reflectance, and a high volumetric percentage of macropores. Meanwhile, if the porosity is about 10%, the deviation measured by MIP is the biggest.

Wearable electronics have sparked a surging demand across diverse fields; however, their widespread adoption remains constrained by costly fabrication processes and reliance on external power sources. This study innovatively integrates magnetic lens technology into conventional electrospinning systems, achieving magnetically focused deposition of PVDF-TrFE nanofibers through precise Lorentz force manipulation of the charged jet under tailored magnetic fields. A systematic investigation was conducted to examine the effects of incorporating magnetic lenses (with and without) and varying electrospinning distances (14, 16, 18, and 20 cm) on film properties, resulting in eight distinct nanofiber membranes with gradient characteristics. Characterization via field-emission scanning electron microscopy (FE-SEM), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) revealed that magnetic-lens-assisted samples exhibited significant morphological and structural optimization, including reduced fiber diameter (decreasing from 1.25 ± 0.38 to 0.82 ± 0.21 μm), improved distribution uniformity (coefficient of variation reduced from 28% to 15%), increased fiber density (rising from 69.5% to 97.4%) and reduced porosity (from 30.5% to 2.6%), increased film thickness (enhanced from 45 ± 5 to 95 ± 8 μm), and elevated β-phase content (rising from 52.3% to 81.7%). Furthermore, the magnetic-lens-assisted sensors demonstrated exceptional performance characteristics, including a 300% enhancement in output voltage (increased from 0.85 to 3.41 V), a 360% improvement in sensitivity (from 12.3 to 56.8 mV/N), excellent linearity (R2 = 0.966), and outstanding durability. Given the extensive adoption of PVDF-TrFE in flexible pressure sensing, wearable electronics, biomedical diagnostics, and soft robotics due to its intrinsic piezoelectric properties, the substantial performance enhancements achieved in this study through magnetic-lens-assisted electrospinning and optimized process parameters further amplify the material’s functional utility. This advancement not only enriches the application landscape of PVDF-TrFE-based sensors but also establishes a scalable pathway toward next-generation, high-sensitivity, self-powered sensing technologies.

The surface-modified molecules of the nanomaterials can interact with the gelator, thereby modulating the self-assembly structure of the gelator molecules. In this paper, to analyze the effect of the surface-functionalized nanomaterial on the self-assembly fiber structure of a urea-based gelator, one-dimensional carbon nanotubes (CNT), hydroxylation (CNTH), and oleic acid-modified (OA/CNTH) carbon nanotubes with “fiber-like” morphology were used as nanomaterials. The results show that the introduction of CNT, CNTH, and OA/CNTH could increase the density, diameter, and cross-linking point of the gel fiber and improve the mechanical stability of the soft nanocomposite. Compared with CNT and CNTH soft-nanocomposite lubricants, OA/CNTH is easier to adsorb to the friction interface, which protects the oxygen-containing lubrication film from friction shear and performs better lubrication.