Search

This article investigates the under-explored potential of utilizing a thin stainless-steel diaphragm coupled with a quartz tuning fork sensor for liquid depth measurements. The focus is on monitoring molten salt fluid levels in nuclear reactors and concentrated solar power systems. Addressing a literature gap, the research explores cantilever-type configurations of a double-ended quartz tuning fork resonator, with a no-load resonance frequency of 17.37 kHz, on thin stainless-steel diaphragms for fluid depth measurement at room temperature. As the fluid depth increases, hydro-static pressure acting on a 20 μ m diaphragm causes deflection, bending a tuning fork. The resulting change in resonance frequency correlates with fluid depth. Experimental setups assess the tuning fork's sensitivity to strain and bending, revealing strain sensitivity of 7.83 Hz/ μ strain (450.78 ppm/ μ strain) and bending sensitivity of 0.09 Hz/ μ m (5.18 ppm/ μ m). The pressure sensor assembly, tested in a water tank, exhibits a sensitivity of − 0.28 Hz/mm (− 16.12 ppm/mm) in a single cantilever-type configuration. Despite a limited linear range, it effectively measures water depth changes as small as 0.7 mm. Exploring a double cantilever-type configuration yields a sensitivity of 0.07 Hz/mm (4.03 ppm/mm) with a broader linear range. The article discusses the reasons for opposite sensitivity and highlights the advantages of each configuration. Beyond molten salt level monitoring, the technology's applications may extend to fluid depth and pressure measurements in industrial and domestic settings. [ABSTRACT FROM AUTHOR]

Determining fluid pressure in Monte Carlo simulations can be a challenging task due to the reduced arsenal of computational tools available to perform such measurements. In addition, none of these tools is general enough to calculate the equilibrium pressure for a wide variety of models. The Gibbs–Duhem method, for example, is a very useful option, but only for pure (one component) systems. To enrich this arsenal, we propose here a direct method to calculate pressure in the canonical ensemble, which could easily be extended to mixtures at low densities. In analogy with the Widom method, our approach is based on the free energy variation with volume, described in terms of the removal of an empty or particle-occupied lattice column. We tested our approach for the lattice gas model and compared the results with exact Onsager solutions. Furthermore, the appearance of thermodynamic instabilities (loops) in the pressure isotherms during the phase transition and their relationship with interface effects are discussed. Finally, a phase diagram is obtained from these isotherms using the Hill construction. [ABSTRACT FROM AUTHOR]

It is a known and experimentally verified fact that the flow of pressure-driven nanoconfined fluids cannot be accurately described by the Navier–Stokes (NS) equations with non-slip boundary conditions, and the measured volumetric flow rates are much higher than those predicted by macroscopical continuum models. In particular, the flow enhancement factors (the ratio between the flow rates directly measured by experiments or simulations and those predicted by the non-slip NS equation) reported by previous studies have more than five orders of magnitude differences. We showcased an anomalous phenomenon in which the flow enhancement exhibits a non-monotonic correlation with fluid pressure within the carbon nanotube with a diameter of 2 nm. Molecular dynamics simulations indicate that the inconsistency of flow behaviors is attributed to the phase transition of nanoconfined fluid induced by fluid pressures. The nanomechanical mechanisms are contributed by complex hydrogen-bonding interactions and regulated water orientations. This study suggests a method for explaining the inconsistency of flow enhancements by considering the pressure-dependent molecular structures. [ABSTRACT FROM AUTHOR]

Desmoplasia in breast cancer leads to heterogeneity in physical properties of the tissue, resulting in disparities in drug delivery and treatment efficacy among patients, thus contributing to high disease mortality. Personalized in vitro breast cancer models hold great promise for high‐throughput testing of therapeutic strategies to normalize the aberrant microenvironment in a patient‐specific manner. Here, tumoroids assembled from breast cancer cell lines (MCF7, SKBR3, and MDA‐MB‐468) and patient‐derived breast tumor cells (TCs) cultured in microphysiological systems including perfusable microvasculature reproduce key aspects of stromal and vascular dysfunction causing impaired drug delivery. Models containing SKBR3 and MDA‐MB‐468 tumoroids show higher stromal hyaluronic acid (HA) deposition, vascular permeability, interstitial fluid pressure (IFP), and degradation of vascular HA relative to models containing MCF7 tumoroids or models without tumoroids. Interleukin 8 (IL8) secretion is found responsible for vascular dysfunction and loss of vascular HA. Interventions targeting IL8 or stromal HA normalize vascular permeability, perfusion, and IFP, and ultimately enhance drug delivery and TC death in response to perfusion with trastuzumab and cetuximab. Similar responses are observed in patient‐derived models. These microphysiological systems can thus be personalized by using patient‐derived cells and can be applied to discover new molecular therapies for the normalization of the tumor microenvironment. [ABSTRACT FROM AUTHOR]

Background: Infusion testing is an established method for assessing CSF resistance in patients with idiopathic normal pressure hydrocephalus (iNPH). To what extent the increased resistance is related to the glymphatic system is an open question. Here we introduce a computational model that includes the glymphatic system and enables us to determine the importance of (1) brain geometry, (2) intracranial pressure, and (3) physiological parameters on the outcome of and response to an infusion test. Methods: We implemented a seven-compartment multiple network porous medium model with subject specific geometries from MR images using the finite element library FEniCS. The model consists of the arterial, capillary and venous blood vessels, their corresponding perivascular spaces, and the extracellular space (ECS). Both subject specific brain geometries and subject specific infusion tests were used in the modeling of both healthy adults and iNPH patients. Furthermore, we performed a systematic study of the effect of variations in model parameters. Results: Both the iNPH group and the control group reached a similar steady state solution when subject specific geometries under identical boundary conditions was used in simulation. The difference in terms of average fluid pressure and velocity between the iNPH and control groups, was found to be less than 6% during all stages of infusion in all compartments. With subject specific boundary conditions, the largest computed difference was a 75% greater fluid speed in the arterial perivascular space (PVS) in the iNPH group compared to the control group. Changes to material parameters changed fluid speeds by several orders of magnitude in some scenarios. A considerable amount of the CSF pass through the glymphatic pathway in our models during infusion, i.e., 28% and 38% in the healthy and iNPH patients, respectively. Conclusions: Using computational models, we have found the relative importance of subject specific geometries to be less important than individual differences in resistance as measured with infusion tests and model parameters such as permeability, in determining the computed pressure and flow during infusion. Model parameters are uncertain, but certain variations have large impact on the simulation results. The computations resulted in a considerable amount of the infused volume passing through the brain either through the perivascular spaces or the extracellular space. [ABSTRACT FROM AUTHOR]

Methane hydrates is regarded as an important alternative energy in the future. Due to the complexity of marine environment, the mechanical parameters and initial stress state of formation have great uncertainties which can affect the wellbore stability in hydrate exploitation. In this study, a new time-dependent analytical model is proposed, considering the influence of hydrate dissociation on the mechanical properties and the partial coupling among pore pressure/temperature/mechanical field. The analytical solutions are verified and validated by numerical solutions. Based on the analytical solution and Mogi-Coulomb failure criterion, the reliability of wellbore stability during drilling in hydrate exploitation is analyzed by the Response Surface Method. Through the reliability analysis, the probability of wellbore instability increases and the safe drilling fluid pressure window range is narrowed with time, and finally tended to be stable at t = 12 h. Hydrate dissociation would lead to a more narrowed pressure window range, about by −38.75%. The most significant parameter whose uncertainty affects the instability probability is initial in-situ stress, followed by the initial internal friction angle and Biot's coefficient. [ABSTRACT FROM AUTHOR]

The complexity of petroleum phases in deep formations plays an important role in the evaluation of hydrocarbon resources. Pressure is considered to have a positive impact on the preservation of liquid oils, yet direct evidence for this phenomenon is lacking in the case of deep reservoirs due to late destruction. Here, we present fluid-inclusion assemblages from a deep reservoir in the Tazhong area of the Tarim Basin, northwestern China, which formed as a direct consequence of fluid pressure evolution. Based on thermodynamic measurements and simulations of the coexisting aqueous and petroleum inclusions in these assemblages, the history of petroleum activities was reconstructed. Our results show that all analyzed fluid-inclusion assemblages demonstrated variable pressure conditions in different charging stages, ranging from hydrostatic to overpressure (a pressure coefficient of up to 1.49). Sequential petroleum charging and partial oil cracking may have been the main contributors to overpressure. By comparing the phases of petroleum and fluid pressures in the two wells, ZS1 and ZS5, it can be inferred that overpressure inhibits oil cracking. Thus, overpressure exerts an important influence on the preservation of liquid hydrocarbon under high temperatures. Furthermore, our results reveal that the exploration potential for liquid petroleum is considerable in the deep reservoirs of the Tarim Basin. [ABSTRACT FROM AUTHOR]

Cancer stem cells (CSCs) are considered the major cause of the occurrence, progression, chemoresistance/radioresistance, recurrence, and metastasis of cancer. Increased interstitial fluid pressure (IFP) is a key feature of solid tumors. Our previous study showed that the distribution of liver cancer stem cells (LCSCs) correlated with the mechanical heterogeneity within liver cancer tissues. However, the regulation of liver cancer's mechanical microenvironment on the LCSC stemness is not fully understood. Here, we employed a cellular pressure‐loading device to investigate the effects of normal IFP (5 mmHg), as well as increased IFP (40 and 200 mmHg) on the stemness of LCSCs. Compared to the control LCSCs (exposure to 5 mmHg pressure loading), the LCSCs exposed to 40 mmHg pressure loading exhibited significantly upregulated expression of CSC markers (CD44, EpCAM, Nanog), enhanced sphere and colony formation capacities, and tumorigenic potential, whereas continuously increased pressure to 200 mmHg suppressed the LCSC characteristics. Mechanistically, pressure loading regulated Yes‐associated protein (YAP) activity and Bcl‐2 modifying factor (BMF) expression. YAP transcriptionally regulated BMF expression to affect the stemness of LCSCs. Knockdown of YAP and overexpression of BMF attenuated pressure‐mediated stemness and tumorgenicity, while YAP‐deficient and BMF‐deletion recused pressure‐dependent stemness on LCSCs, suggesting the involvement of YAP/BMF signaling axis in this process. Together, our findings provide a potential target for overcoming the stemness of CSCs and elucidate the significance of increased IFP in cancer progression. [ABSTRACT FROM AUTHOR]

Trillions of cubic meters of gas reserve have been found in the Sinian Dengying carbonate reservoirs with normal pressure in the central Sichuan Basin, while no industrial gas reservoir have been detected in the Sinian Dengying reservoir with normal pressure in the eastern Sichuan Basin. The pore fluid pressure of gas reservoir is usually closely related to total gas content. To investigate the pore fluid pressure evolution and its implication for gas reserve preservation in the Sinian Dengying reservoir of the central and eastern Sichuan Basin, we conducted a comprehensive analysis including fluid inclusion petrography, microthermometry and Raman spectroscopy. The timings of gas inclusions captured in the central and eastern Sichuan Basin occurred from 175 to 92 Ma and 191 to 183 Ma, respectively. The presence of two‐phase vapour‐solid bitumen inclusions with similar phase proportions in a single fluid inclusion assemblage of fluorite provides direct evidence of in situ oil cracking to gas. The widespread solid bitumen from the Sinian Dengying reservoir in the central Sichuan Basin indicates the existence of massive oil cracking, which results in the formation of overpressure in the reservoir. Pore fluid pressure evolution of the Sinian Dengying reservoir of the central Sichuan Basin experiences normal pressure stage (200–155 Ma), overpressure development stage (155–90 Ma) and overpressure release stage (90–0 Ma). The maximum pore fluid pressure and its corresponding pressure coefficient of the Sinian Dengying reservoir of the central Sichuan Basin are approximately 141.4 MPa and 1.95, respectively. The overpressure development stage reflects the processes of oil cracking and gas accumulation, and the overpressure release stage reflects the dissipation of some natural gas in the Sinian Dengying reservoir of the central Sichuan Basin. The pore fluid pressure of the Sinian Dengying reservoir in the eastern Sichuan Basin has maintained at normal pressure since 200 Ma, indicating that the gas reservoir was small during the oil cracking stage and natural gas completely leaked due to tectonic uplift. [ABSTRACT FROM AUTHOR]

Downward flow of surface-derived water deep into the upper crust is investigated using 2-D coupled hydrothermal numerical models. In the models, downward flow is driven by either topographic gradients or seismic pumping, while it is facilitated by large episodic variations in fault permeability, intended to mimic fracturing and healing on a fault over repeated seismic cycles. The models show that both forcing scenarios are equally capable of driving surface-derived fluid to the base of faults at 10 km depth in several tens of thousands of years under certain conditions. Downward flow of cold fluid occurs almost exclusively during and shortly after earthquakes, while during the remaining portion of the seismic cycle fluids remain relatively stationary while they undergo thermal relaxation (i.e. heating). Rapid downward flow is favoured by a large coseismic permeability, long permeability healing timescale and large coseismic dilatancy or high topographic relief above the fault at the surface. However, downward fluid flow is completely inhibited if fluid pressures exceeds the hydrostatic gradient, even by modest amounts, which suggests that deep fluid infiltration is unlikely to occur in every region. [ABSTRACT FROM AUTHOR]

Moderate magnitude earthquakes and seismic sequences frequently develop on fault systems, but whether they are linked to future major ruptures is always ambiguous. In this study, we investigated a seismic sequence that has developed within a portion of the stretching region of the Apennines in Italy where moderate to large earthquakes are likely to occur. We captured a total of 2039 aftershocks of the 2023 September 18, M w 4.9 earthquake occurred during the first week, by using machine-learning (ML) based algorithms. Aftershocks align on two 5–7 km long parallel faults, from a length that exceeds what is expected from the main shock magnitude. The segments are ramping at about 6 km depth on closely spaced N100 striking 70 N dipping planes, at a distance of some kilometres from the main shock hypocentre. Our results indicate that even moderate magnitude events trigger seismicity on a spread set of fault segments around the main shock hypocentre, revealing processes of interaction within the crustal layer. The possibility that larger earthquakes develop during seismicity spread is favoured by pore pressure diffusion, in relation with the closeness to criticality of fault segments. Based on the very rapid activation of seismicity on the entire system and a back-front signal from the hypocentre of the main event, we infer that fluid pressure, initially high within the crustal layer, rapidly dropped after the main shock. Our study reinforces the importance of timely extracting information on fault geometry and seismicity distribution on faults. ML-based methods represent a viable tool for semi-real-time application, yielding constraints on short-time forecasts. [ABSTRACT FROM AUTHOR]

Background: After aneurysmal subarachnoid hemorrhage (aSAH), elevated intracranial pressure (ICP) due to disrupted cerebrospinal fluid (CSF) dynamics is a critical concern. An external ventricular drainage (EVD) is commonly employed for management; however, optimal strategies remain debated. The randomized controlled Earlydrain trial showed that an additional prophylactic lumbar drainage (LD) after aneurysm treatment improves neurological outcome. We performed a post hoc investigation on the impact of drainage volumes and critical ICP values on patient outcomes after aSAH. Methods: Using raw patient data from Earlydrain, we analyzed CSF drainage amounts and ICP measurements in the first 8 days after aSAH. Outcomes were the occurrence of secondary infarctions and the score on the modified Rankin scale after 6 months, dichotomized in values of 0–2 as favorable and 3–6 as unfavorable. Repeated measurements were considered with generalized estimation equations. Results: Earlydrain recruited 287 patients, of whom 221 received an EVD and 140 received an LD. Higher EVD volumes showed a trend to more secondary infarctions (p = 0.09), whereas higher LD volumes were associated with less secondary infarctions (p = 0.009). The mean total CSF drainage was 1052 ± 659 mL and did not differ concerning infarction and neurological outcome. Maximum ICP values were higher in patients with poor outcomes but not related to drainage volumes via EVD. After adjustment for aSAH severity and total CSF drainage, higher LD volume was linked to favorable outcome (per 100 mL: odds ratio 0.61 (95% confidence interval 0.39–0.95), p = 0.03), whereas higher EVD amounts were associated with unfavorable outcome (per 100 mL: odds ratio 1.63 (95% confidence interval 1.05–2.54), p = 0.03). Conclusions: Findings indicate that effects of CSF drainage via EVD and LD differ. Higher amounts and higher proportions of LD volumes were associated with better outcomes, suggesting a potential quantity-dependent protective effect. Optimizing LD volume and mitigating ICP spikes may be a strategy to improve patient outcomes after aSAH. Clinical trial registration: ClinicalTrials.gov identifier: NCT01258257. [ABSTRACT FROM AUTHOR]

In this paper, we develop two discontinuous Galerkin (DG) finite element methods to solve the linear poroelasticity in the total pressure formulation, where displacement, fluid pressure, and total pressure are unknowns. The fully-discrete standard DG and conforming DG methods are presented based on the discontinuous approximations in space and the implicit Euler discretization in time. Compared to the standard DG method with penalty terms, the conforming DG method removes all stabilizers and maintains conforming finite element formulation by utilizing weak operators defined over discontinuous functions. The two methods provide locally conservative solutions and achieve locking-free properties in poroelasticity. We also derive the well-posedness and optimal a priori error estimates, which show that our methods satisfy parameter-robustness with respect to the infinitely large Lamé constant and the null-constrained specific storage coefficient. Several numerical experiments are performed to verify these theoretical results, even in heterogeneous porous media. [ABSTRACT FROM AUTHOR]

We investigated stress drops during an earthquake swarm in northeastern Noto Peninsula, central Japan, which is characterized by ongoing seismic activity in four clusters. We focused on the spatiotemporal distribution of the static stress drop and its relationship with the source faults of the earthquake swarm. Employing the empirical Green's function method, we estimated static stress drops for 90 earthquakes of MJMA 3.0–5.4. We obtained logarithmic mean stress drops of 13 MPa and 19 MPa from P-wave and S-wave analyses, respectively, which were typical values for crustal earthquakes. We comprehensively analyzed the spatiotemporal distribution of static stress drops in the northern cluster due to the abundance of available data and clarity of fault structures there. We observed larger static stress drops for earthquakes along shallow portions of the source faults, as defined by the hypocentral distribution during a given period. Conversely, we observed smaller static stress drops for earthquakes at medial parts along the faults. These results suggest higher fault strength at shallower parts along the faults and reduced fault strength at medial parts. We attribute the high fault strength at shallow parts to low pore fluid pressure after only limited fluid diffusion near the fault terminus. In contrast, we attribute the reduction in fault strength at medial parts to high pore fluid pressure within the fault following penetration by migrating fluids. [ABSTRACT FROM AUTHOR]

The aim of this paper is to analyze the pathophysiological mechanisms acting in very early classic Guillain‐Barré syndrome (GBS) (≤4 days of symptomatic onset). In this inaugural period, both in GBS and its animal model, experimental autoimmune neuritis, the outstanding pathological feature is inflammatory edema predominating in proximal nerve trunks, particularly spinal nerves, and possibly in preterminal nerve segments. Nerve trunks external to the subarachnoid angle possess epi‐ perineurium that is relatively inelastic and of low compliance. Here such edema can increase endoneurial fluid pressure that, when sufficiently critical, may stretch the perineurium and constrict transperineurial microcirculation, compromising blood flow and producing the potential for ischemic nerve injury, whose consequence is rapid partial or complete loss of nerve excitability. These histopathological features correlate well with electrophysiological and imaging findings reported in early GBS stages. Spinal nerve edema and ischemia help to understand the pattern of Wallerian‐like degeneration observed in the axonal form of GBS, predominating in motor spinal roots at their exit from the dura matter (spinal nerves) with centrifugal distribution in more distant motor nerve trunks, and centripetal extension to the distal portion of intrathecal roots. The similarity of initial pathogenic mechanisms between demyelinating and axonal forms of GBS explains why an early increase of serum biomarkers of axonal damage is detected in both forms. In conclusion, knowledge of the microscopic anatomy of the peripheral nervous system is an essential step for a reliable understanding of pathophysiological mechanisms operating in the early phase of any classic GBS subtype. [ABSTRACT FROM AUTHOR]

Soft interfaces are ubiquitous in nature, governing quintessential hydrodynamics functions, like lubrication, stability, and cargo transport. It is shown here how a magnetic pressure at a magnetic–nonmagnetic fluid interface results in an ultra‐soft interface with nonlinear elasticity and tunable viscous shear properties. The balance between magnetic pressure, viscous stress, and Laplace pressure results in a deformed and stable liquid‐in‐liquid tube with apparent elasticity in the range of 2–10 kPa, possibly extended by a proper choice of liquid properties. Such highly deformable liquid–liquid interfaces of arbitrary shape with vanishing viscous shear open doors to unique microfluidic phenomena, biomaterial flows and complex biosystems mimicking. [ABSTRACT FROM AUTHOR]

We study the behaviour of a particle bed immersed in water when a flow generated by an oscillating plate is induced above it. We first consider a rigid plate submerged and oscillated over a particle bed. During upward motion of the plate, a portion of the bed fails, allowing particle displacement, and the bed surface to deform into a heap. We have already determined the flow of the fluid above and within the bed. This work describes the particle motion within the failed region of the bed: when the particles are mobile, they follow the fluid. We depth average the balance of mass and obtain an evolution equation for the displacement of the bed surface. We solve this equation and compare the predictions with the measurements of surface displacement in earlier experiments on rigid square plates. We carry out new experiments to measure the surface displacements under elongated plates. Elongated rigid plates behave similarly to the rigid square ones. Flexible plates produce multiple heaps. We determine that the peaks of these heaps are correlated with the flexural modes of the plates and occur at points along the bed at which the fluid pressure has its extreme values. Different plate flexural modes, resulting in different numbers of heaps, are produced by driving the plate at different frequencies. The particle motion within the bed and heap evolution under a flexible plate can be roughly described by regarding it as two or more rigid plates. We test the predictions of the theory against experiments. [ABSTRACT FROM AUTHOR]

The traditional specific storage coefficient (Ss) was defined under two assumptions. One is that aquifer rock deforms only in the vertical direction, and the other is that the average rock stress remains unchanged. Consequently, Ss is irrelevant to the shear modulus of rock (G). In this paper, the Biot theory is used to derive a new specific storage coefficient (Ss∗) with the natural deformation of rock. Ss∗ appears to be relevant to G. Compressed glass beads and Berea sandstone are used for illustration. At frequencies lower than 10 kHz, the equation of groundwater flow with Ss∗ yields the same phase velocity and quality factor as the Biot theory, and therefore, it is capable of accurately predicting fluid pressure diffusion in the low‐frequency regime. The results also show that Ss is 16%–17% higher than Ss∗. In conclusion, the latter one is superior to the former in its consistency with the Biot theory and unconstraint by the aforementioned two assumptions. [ABSTRACT FROM AUTHOR]

We investigate the dynamics of plasma-based acceleration processes with collisionless particle dynamics and non-negligible thermal effects. We aim at assessing the applicability of fluid-like models, obtained by suitable closure assumptions applied to the relativistic kinetic equations, thus not suffering from statistical noise, even in the presence of a finite temperature. The work here presented focuses on the characterization of pressure anisotropies, which crucially depend on the adopted closure scheme, and hence are useful to discern the appropriate thermal fluid model. To this aim, simulation results of spatially resolved fluid models with different thermal closure assumptions are compared with the results of particle-in-cell simulations at changing temperature and amplitude of plasma oscillations. [ABSTRACT FROM AUTHOR]

We measured the spatiotemporal evolution of pore pressure on‐ and off‐fault during failure and slip in initially intact Westerly granite under triaxial conditions. The pore pressure perturbations in the fault zone and the surrounding bulk presented opposite signs upon shear failure, resulting in large pore pressure gradients over small distances (up to 10 MPa/cm). The on‐fault pore pressure dropped due to localized fault dilation associated with fracture coalescence and fault slip, and the off‐fault pore pressure increased due to bulk compaction resulting from the closure of dilatant microcracks mostly parallel to the maximum compression axis. We show that a reduction in bulk porosity and relatively undrained conditions during failure are necessary for the presence of the off‐fault pore pressure elevation. Considering this phenomenon as a consequence of a main shock, we further show that off‐fault pore pressure increase has the potential to trigger neighboring fault instabilities. In nature, we expect the phenomenon of off‐fault pore pressure increase to be most relevant for misoriented faults, where the pre‐rupture stresses can be large enough to reach the dilatancy threshold in the wall rocks. Plain Language Summary: The interplay between fluid flow and rock deformation plays a pivotal role in understanding the mechanics of geological processes and engineering activities, particularly in the context of seismic events. The slip of tectonic faults during earthquakes is expected to produce non‐uniform variations of fluid pressure, notably along the fault plane and in its vicinity. These variations may have a substantial impact on the dynamics of fault slip, an aspect that has thus far eluded precise quantification. We analyzed the evolution of pore pressure during simulated earthquakes in the laboratory, focusing on the contrast in pore pressure dynamics on and off the fault within a cm‐sized sample of granite, a rock representative of the continental crust. Opposing trends were observed upon rock failure: The on‐fault pore pressure dropped, which can be attributed to dilation within the fault zone (a well documented phenomenon) while the off‐fault pressure increased, which was a surprise. The off‐fault pressure increase can be explained by the rapid closure of small cracks upon unloading of the rock mass as the fault is formed. During earthquakes in nature, we expect off‐fault fluid pressure to increase in regions where initial stresses are elevated, for example, where fault geometry is complex. Key Points: Opposite variations of pore pressure occur on and off the fault upon shear failureOn‐fault pore pressure drop results from fault dilatancyOff‐fault pore pressure elevation requires bulk porosity reduction and undrained conditions during failure [ABSTRACT FROM AUTHOR]

Shijia Gold Deposit is a quartz vein-type gold deposit located in the northern part of the Qixia - Penglai - Fushan Metallogenic Belt. The mineralization process can be broadly divided into 4 stages: quartz pyrite stage (1), gold-quartz - pyrite stage (II), gold quartz polymetallic sulfide stage (III), and quartz carbonate stage (IV). The salinity of the ore-forming fluid ranges from 1.83% to 10.74%, with a density of 0.61-0.90 g/cm³, indicating low salinity and low-density fluids. The mineralization temperature is between 275 °C and 325 °C, with fluid pressures ranging from 50 MPa to 92 MPa, and a mineralization depth of 1.673.07 km. The comprehensive characteristics reveal that this deposit is a medium-temperature hydrothermal vein-type gold deposit controlled by steeply dipping extensional faults in the upper part of a granite dome, with mantle-derived fluids, magmatic fluids, and meteoric water jointly contributing to the mineralization. [ABSTRACT FROM AUTHOR]

This paper presents a new variational phase-field model aimed at investigating the fully coupled hydro-mechanical-damage processes in saturated quasi-brittle rocks. Biot's poroelasticity theory is incorporated with a damage-dependent permeability to describe both Darcy-type seepage in the solid matrix and Poiseuille-type flows in the cracked domain. The fluid pressure is introduced into a unified phase-field framework modified with a mixed-mode crack driving force. This framework can predict and reproduce complex crack initiation and propagation while explicitly determining the apparent crack width. First, the formulations of the proposed model are given. Then the fully coupled system is implemented using the finite element method and an alternate minimization Newton–Raphson iterative solver, facilitated by user subroutines provided by the software ABAQUS. The proposed model is validated by three benchmark problems. Subsequently, fracture propagation, pressure diffusion, and mechanical behavior are simulated and discussed in homogenous and heterogeneous quasi-brittle rock samples with pre-existing flaws under uniaxial compression, respectively. Finally, the proposed model is applied to simulate the damage evolution and investigate the fluid pressure distribution in jointed rock structures. The practicality and computational efficiency of the proposed model in accurately simulating realistic crack propagation and fluid pressure distribution in rock engineering problems are demonstrated. Highlights: A new variational phase-field model for predicting hydro-mechanical coupled fracture propagation is developed. A modified mixed-mode crack driving force is well incorporated in the proposed model. The three-field coupled system is efficiently solved by the implementation of a dual-layer numerical structure in ABAQUS. The model is well validated and then applied to simulate crack propagation in rock samples and jointed rock structures. [ABSTRACT FROM AUTHOR]

Numerous nanomedicines have been developed recently that can accumulate selectively in tumours due to the enhanced permeability and retention (EPR) effect. However, the high interstitial fluid pressure (IFP) in solid tumours limits the targeted delivery of nanomedicines. We were previously able to relieve intra-tumoural IFP by low-frequency non-focused ultrasound (LFNFU) through ultrasonic targeted microbubble destruction (UTMD), improving the targeted delivery of FITC-dextran. However, the accumulation of nanoparticles of different sizes and the optimal acoustic pressure were not evaluated. In this study, we synthesised Cy5.5-conjugated mesoporous silica nanoparticles (Cy5.5-MSNs) of different sizes using a one-pot method. The Cy5.5-MSNs exhibited excellent stability and biosafety regardless of size. MCF7 tumour-bearing mice were subjected to UTMD over a range of acoustic pressures (0.5, 0.8, 1.5 and 2.0 MPa), and injected intravenously with Cy5.5-MSNs. Blood perfusion, tumour IFP and intra-tumoural accumulation of Cy5.5-MSNs were analysed. Blood perfusion and IFP initially rose, and then declined, as acoustic pressure intensified. Furthermore, UTMD significantly enhanced the accumulation of differentially sized Cy5.5-MSNs in tumour tissues compared to that of the control group, and the increase was sevenfold higher at an acoustic pressure of 1.5 MPa. Taken together, UTMD enhanced the infiltration and accumulation of Cy5.5-MSNs of different sizes in solid tumours by reducing intra-tumour IFP. The synthesis of Cy5.5-MSN and the effect of UTMD on its infiltration into tumours (produced using Figdraw, ). (A) The synthesis route of Cy5.5-MSN. (B, C) The impact of UTMD on the infiltration of Cy5.5-MSN into tumours. [ABSTRACT FROM AUTHOR]

We present a complete numerical analysis for a general discretization of a coupled flow–mechanics model in fractured porous media, considering single-phase flows and including frictionless contact at matrix–fracture interfaces, as well as nonlinear poromechanical coupling. Fractures are described as planar surfaces, yielding the so-called mixed- or hybrid-dimensional models. Small displacements and a linear elastic behavior are considered for the matrix. The model accounts for discontinuous fluid pressures at matrix–fracture interfaces in order to cover a wide range of normal fracture conductivities. The numerical analysis is carried out in the Gradient Discretization framework (see J. Droniou, R. Eymard, T. Gallouët, C. Guichard, and R. Herbin [ The gradient discretisation method , Springer, Cham, 2018]), encompassing a large family of conforming and nonconforming discretizations. The convergence result also yields, as a by-product, the existence of a weak solution to the continuous model. A numerical experiment in 2D is presented to support the obtained result, employing a Hybrid Finite Volume scheme for the flow and second-order finite elements (\mathbb {P}_2) for the mechanical displacement coupled with face-wise constant (\mathbb P_0) Lagrange multipliers on fractures, representing normal stresses, to discretize the contact conditions. [ABSTRACT FROM AUTHOR]

Primary waves produced by large ships in confined waterways can threaten the sustainability and safety of coastal regions near maritime shipping routes, but the present understanding and predictability of primary wave shallow-water characteristics is hindered by a scarcity of available field observations. This study presents hydrodynamic measurements from 296 primary waves observed in 3.5 to 4.4 m mean water depth throughout four deployments on the channel margins of the Savannah River in Georgia, USA. Ship details and tidally varying waterway parameters are paired with pressure and fluid velocity data to investigate relationships between ship characteristics, waterway conditions, and primary wave magnitudes. Findings show that although larger and faster ships tend to produce larger primary waves, there are inconsistencies among the magnitudes of waves generated by similar ship passages. Additionally, depression prediction equations perform well for most observations, but a small group of "atypically-large" primary waves with depressions exceeding 75 cm are consistently underpredicted and require further investigation. Hydrodynamic, waterway, and ship data are made available in the Supplemental Data. [ABSTRACT FROM AUTHOR]

Bernoulli pads are traditionally used for noncontact pick-and-place operations in industry. The normal force produced by a Bernoulli pad allows it to adhere to an object or workpiece. In addition to the normal force, the pad produces shear forces, which allows it to clean a workpiece without contact. A direct relationship between the inlet fluid power and the shear losses motivates us to explore other methods of providing power to the system with the objective of increasing shear forces and thereby improving cleaning efficacy. Here, we numerically investigate a system in which additional mechanical power is added by rotating the Bernoulli pad. The rotating system provides additional fluid forces (normal and shear) for the same inlet fluid power. For a specific pad that we investigated, the maximum wall shear stress increased by ≈15% and the normal force changed from +1.4 N (repulsive) to -6.6 N (attractive) for change in the rotational speed by 60 rad/s. Also, for a given normal attractive force, a stable equilibrium configuration can exist for two mass flow rates, with the higher mass flowrate resulting in a higher stiffness of the flow field. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Drainage & Irrigation Machinery Engineering / Paiguan Jixie Gongcheng Xuebao is the property of Editorial Department of Drainage & Irrigation Machinery Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A theoretical simulation is performed to evaluate how microcracks affect the flow resistance in tumors during the convection-enhanced delivery (CED) of nanofluids. Both Darcy's law and the theory of poroelasticity are used to understand fluid transport with or without microcrack introduction and/or enlargement. The results demonstrate significantly altered pressure and velocity fields in a spherical tumor with a radius of 10 mm due to the presence of a microcrack with a radius of 0.05 mm and length of 3 mm. The non-uniform fluid pressure field enlarges the original cylindrical microcrack to a frustum, with the crack volume more than doubled. Due to the larger permeability and porosity in the microcrack, flow in the tumor is much easier. One finds that the flow resistance with the enlarged microcrack is reduced by 14% from the control without a microcrack. Parametric studies are conducted to show that larger crack radii, longer crack lengths and higher infusing pressures result in further resistance reductions. The largest resistance reduction occurs when the infusing pressure is 4 × 105 Pa and the microcrack is 9 mm long, up to 18% from the control. We conclude that introducing a microcrack is an effective way to facilitate nanofluid delivery in porous tumors using CED. [ABSTRACT FROM AUTHOR]

The Mississippi River Delta Front (MRDF) is a subaqueous apron of rapidly deposited and weakly consolidated sediment extending from the subaerial portions of the Birdsfoot Delta of the Mississippi River, long characterized by mass-wasting sediment transport. Four (4) depositional environments dominate regionally (an undisturbed topset apron, mudflow gully, mudflow lobe, and prodelta), centering around mudflow distribution initiated by a variety of factors (hurricanes, storms, and fluid pressure). To better understand the spatiotemporal scales of the events as well as the controlling processes, eight cores (5.8–8.0 m long) taken offshore from the South Pass (SP) and the Southwest Pass (SWP) were analyzed for gamma density, grain size, sediment fabric (X-radiography), and geochronology (210Pb/137Cs radionuclides). Previous work has focused on the deposition of individual passes and has been restricted to <3 m core penetration, limiting its geochronologic completeness. Building on other recent studies, within the mudflow gully and lobe cores, the homogeneous stepped profiles of 210Pb activities and the corresponding decreased gamma density indicate the presence of gravity-driven mass failures. 210Pb/137Cs indicates that gully sedimentary sediment accumulation since 1953 is greater than 580 cm (sediment accumulation rate [SAR] of 12.8 cm/y) in the southwest pass site, and a lower SAR of the South Pass gully sites (2.6 cm/y). This study shows that (1) recent dated mudflow deposits are identifiable in both the SWP and SP; (2) SWP mudflows have return periods of 10.7 y, six times more frequent than at the SP (66.7 y); (3) 210Pb inventories display higher levels in the SWP area, with the highest focusing factors in proximal/gully sedimentation, and (4) submarine landslides in both study areas remain important for sediment transport despite the differences in sediment delivery and discharge source proximity. [ABSTRACT FROM AUTHOR]

The use of environmentally friendly hydraulic fluids is frequently influenced by the temperature reached in the hydraulic circuit. This paper presents an analysis of the effect of temperature on the lifetime of the hydraulic fluid and the hydraulic pump. The test was carried out by continuous loading with a pressure of 21 MPa and a temperature of 96 °C for 100 h. A pressure valve was used for the continuous loading and the temperature was maintained using a cooler. At intervals of 25 h, the flow characteristics of the hydraulic pump were measured and oil sampling was carried out. Subsequently, a comprehensive chemical and physical analysis was carried out. In the present paper, a comprehensive analysis of the influence of eco-friendly hydraulic fluid on the operation of a gear hydraulic pump has been carried out. The study itself did not show the negative influence of the eco-friendly hydraulic fluid on the operation of the gear hydraulic pump. It can be expected that the results of the study will enable the use of eco-friendly hydraulic fluids in environmentally sensitive areas. [ABSTRACT FROM AUTHOR]

In air-cooled data centers, hot aisle containment is used to separate hot and cold air from mixing to improve cooling effectiveness. However, this creates a significant pressure imbalance between the cold and hot aisles, with the latter being high. The hot aisle high pressure creates bac pressure that pushes against the server-unit fan system, which subsequently results in hot recirculation and insufficient server-unit cooling. This study examines the application of series-configured server fans with the intention of increasing the system pressure head to overcome the hot aisle containment back pressure and eliminate server hot air recirculation. A detailed computational fluid dynamics model for the Dell 2950 2U server is calibrated and validated using existing experimental test results. Furthermore, the impact of changing the server fan system to a series configuration by adding four or more server fans is investigated under different hot-aisle pressure conditions. It was found that changing the server fan system configuration from parallel to series arrangement positively improved the available system static pressure, but it did not result in the elimination of hot air recirculation. The server with the series-configured fan system experienced an average inlet air temperature increase of 9% when compared to the original server under similar conditions. This study serves as a base for integrating liquid and air-cooling systems to form hybrid cooling systems for high-density racks in legacy data centers. [ABSTRACT FROM AUTHOR]

Hydration and dehydration reactions play pivotal roles in plate tectonics and the deep water cycle, yet many facets of (de)hydration reactions remain unclear. Here, we study (de)hydration reactions where associated solid density changes are predominantly balanced by porosity changes, with solid rock deformation playing a minor role. We propose a hypothesis for three scenarios of (de)hydration front propagation and test it using one‐dimensional hydro‐mechanical‐chemical models. Our models couple porous fluid flow, solid rock volumetric deformation, and (de)hydration reactions described by equilibrium thermodynamics. We couple our transport model with reactions through fluid pressure: the fluid pressure gradient governs porous flow and the fluid pressure magnitude controls the reaction boundary. Our model validates the hypothesized scenarios and shows that the change in solid density across the reaction boundary, from lower to higher pressure, dictates whether hydration or dehydration fronts propagate: decreasing solid density causes dehydration front propagation in the direction opposite to fluid flow while increasing solid density enables both hydration and dehydration front propagation in the same direction as fluid flow. Our models demonstrate that reactions can drive the propagation of (de)hydration fronts, characterized by sharp porosity fronts, into a viscous medium with zero porosity and permeability; such propagation is impossible without reactions, as porosity fronts become trapped. We apply our model to serpentinite dehydration reactions with positive and negative Clapeyron slopes and granulite hydration (eclogitization). We use the results of systematic numerical simulations to derive a new equation that allows estimating the transient, reaction‐induced permeability of natural (de)hydration zones. Plain Language Summary: We investigate reactions of hydration, which is the incorporation of water into a rock, and dehydration, which is the liberation of water from a rock, with simple mathematical models. These reactions are critical in understanding processes like plate tectonics, but many aspects of how hydration or dehydration fronts move through a rock are unclear. Our research focuses on reactions where changes in density are mostly balanced by changes in pore space, termed porosity, rather than the deformation of the solid rock. We developed mathematical models that combine fluid flow, rock deformation, and hydration/dehydration reactions. We derived simple equations that predict changes in porosity during hydration and dehydration, even when the solid rock deforms simultaneously. We found that whether a rock hydrates or dehydrates depends on how its solid density changes with increasing pressure during the reaction. By systematically studying our model, we discovered that the speed of hydration and dehydration is not influenced by the interval of fluid pressure over which the reaction occurs or the relationship between porosity and permeability. We present an equation that can be used to estimate permeability from natural (de)hydration zones. Key Points: (De)hydration fronts propagate into zero‐permeability rock if the solid density of the reactant is smaller than the one of the productExternal fluid flux compensates the imbalance between fluid generated/consumed by reaction and fluid needed to fill generated porosityResults of systematic numerical simulations allow estimating the transient, reaction‐induced permeability of natural (de)hydration zones [ABSTRACT FROM AUTHOR]

Copyright of Acta Scientiarum Naturalium Universitatis Pekinensis is the property of Editorial Office of Acta Scientiarum Naturalium Universitatis Pekinensis and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Sealing rings are the core components of flange sealing structures and play a crucial role in the storage and operation of gas generators. The aging and deformation of seals affect the safe operation of the device. This paper aims to investigate the effect of rubber aging on the sealing performance of the components, which is realized by nonlinear finite element analysis. Firstly, an accelerated degradation test method was used to obtain the compression permanent deformation and stress–strain curve of rubber during the aging process. A two-dimensional finite element model of the sealing structure was constructed and the Yeoh model was utilized to describe the mechanical response of rubber. During the simulation, the contact area was modified based on the compression permanent deformation, and the Yeoh model was updated based on the stress–strain curve changes obtained by the test. The impact of key parameters such as material property changes, rubber physical section deformation, and fluid pressure on sealing performance during the seal ring aging process was systematically studied. The numerical results indicate that due to the aging deformation of rubber seals, there is a significant decrease in contact stress and contact width, as well as a shift in maximum equivalent stress area. Taking into account these findings, this study proposes a new design concept for sealing structures. This provides a relatively simple research method for studying flange sealing structure performance. [ABSTRACT FROM AUTHOR]

Hydraulic pumps are essential components in hydraulic systems requiring precise and powerful motion control. The choice of pump depends on factors like the required flow rate, pressure, fluid type, and application environment. Pulsation in the context of hydraulic actuation systems refers to the periodic fluctuation of pressure and fluid flow rate within the hydraulic circuit, often caused by the operation of the pump or other components. Pulsation can have several effects on the performance and reliability of a hydraulic system, and understanding its causes and mitigation strategies is essential. [ABSTRACT FROM AUTHOR]

ABSTRACT This study provides new mineral chemistry data together with micro‐thermometric measurements on fluid inclusions hosted in ultramafic xenoliths (lherzolite, wehrlite, and dunite) brought to the surface by the last Mt. Vulture volcano activity (140 ka; southern Italy), and fed by melilitite‐carbonatite magmas. Petrographic evidence and mineralogical compositions of Mt. Vulture xenoliths are consistent with an origin in the upper mantle. Fluid inclusions in rock‐forming minerals of lherzolite and wehrlite xenoliths are CO2‐dominated. The equilibrium temperature calculated by geothermometric estimates ranges from 1039 C (±36°C) to 1142°C (±15°C), and entrapment pressures of fluid inclusions with post‐trapping re‐equilibration correspond to the local crust–mantle boundary (32 km depth), and to a shallow reservoir located at 12–14 km depth. These results contribute to constrain the origin of these xenoliths and the depth of storage of magmas erupted from Mt. Vulture, where carbonatite‐like metasomatism and mantle‐derived CO2 degassing occur. [ABSTRACT FROM AUTHOR]

Deficit of oxygen and nutrients in the tumor microenvironment (TME) triggers abnormal angiogenesis that produces dysfunctional and leaky blood vessels, which fail to adequately perfuse tumor tissues. Resulting hypoxia, exacerbation of metabolic disturbances, and generation of an immunosuppressive TME undermine the efficacy of anticancer therapies. Use of carefully scheduled angiogenesis inhibitors has been suggested to overcome these problems and normalize the TME. Here, we propose an alternative agonist-based normalization approach using a derivative of the C-type natriuretic peptide (dCNP). Multiple gene expression signatures in tumor tissues were affected in mice treated with dCNP. In several mouse orthotopic and subcutaneous solid tumor models including colon and pancreatic adenocarcinomas, this well-tolerated agent stimulated formation of highly functional tumor blood vessels to reduce hypoxia. Administration of dCNP also inhibited stromagenesis and remodeling of the extracellular matrix and decreased tumor interstitial fluid pressure. In addition, treatment with dCNP reinvigorated the antitumor immune responses. Administration of dCNP decelerated growth of primary mouse tumors and suppressed their metastases. Moreover, inclusion of dCNP into the chemo-, radio-, or immune-therapeutic regimens increased their efficacy against solid tumors in immunocompetent mice. These results demonstrate the proof of principle for using vasculature normalizing agonists to improve therapies against solid tumors and characterize dCNP as the first in class among such agents. Editor's summary: Tumors often have abnormal and dysfunctional blood vessels that are in part responsible for poor drug delivery and thus reduced efficacy of treatment. Here, Lu et al. have developed a derivative of the C-type natriuretic peptide (dCNP) to normalize vascular structures of tumors to improve therapy efficacy. They demonstrated that this modified dCNP had superior pharmacokinetic and pharmacodynamic properties as compared with native CNP. In addition, administration of dCNP to multiple mouse models remodeled tumor blood vessels and improved antitumorigenic activity of standard monotherapies. This represents a promising compound that could improve therapeutic efficacy of multiple therapies for patients with cancer that requires further study. —Dorothy Hallberg [ABSTRACT FROM AUTHOR]

Understanding the coupling between rock permeability, pore pressure, and fluid flow is crucial, as fluids play an important role in the Earth's crustal dynamics. We measured the distribution of fluid pressure during fluid‐flow experiments on two typical crustal lithologies, granite and basalt. Our results demonstrate that the pore‐pressure distribution transitions from a linear to a non‐linear profile as the imposed pore‐pressure gradient is increased (from 2.5 to 60 MPa) across the specimen. This non‐linearity results from the effective pressure dependence of permeability, for which two analytical formulations were considered: an empirical exponential and a new micromechanics‐based model. In both cases, the non‐linearity of pore pressure distribution is predicted. Using a compilation of permeability versus Terzaghi's effective pressure data for granites and basalts, we show that our micromechanics‐based model has the potential to predict the pore pressure distribution over the range of effective pressures expected within the brittle crust. Plain Language Summary: Fluids distributions and fluid migrations play an important role in the Earth's crustal dynamics and how fluids migrate through a rock will depend primarily on permeability. However, the permeability of crustal rocks may exhibit important pressure dependence, because cracks and fractures will increasingly close with increasing tectonic pressure. In this experimental study, we show that the couplings between increasing pressure, crack closure, and permeability reduction may result in non‐linear pore pressure distributions on a rock specimen at the laboratory scale, which confirms for the first time pioneering theoretical and experimental works. Two simple analytical expressions of the pressure dependence of permeability predict this non‐linearity. One empirical expression, most commonly used in the literature, takes the form of an exponential. The second one, a new model, based on crack micromechanics, was developed within this work and shown to outperform the exponential formulation at low Terzaghi's effective pressure. Key Points: Pore pressure was measured locally in rocks exhibiting pressure‐dependent permeabilityWe observed a transition from linear to nonlinear pore pressure distribution with increasing fluid pressure gradientsA new, micromechanics‐based, analytical model was developed for the pressure dependence of permeability in microcracked rocks [ABSTRACT FROM AUTHOR]

Enhanced geothermal systems (EGSs) developed by hydraulic stimulation are promising for exploiting petrothermal heat by improving fluid pathways in low-permeable geothermal reservoir rocks. However, fluid injection into the subsurface can potentially cause large seismic events by reactivating pre-existing faults, which is a significant barrier to EGSs. The management of injection-induced seismicity is, therefore, essential for the success of EGSs. During the hydraulic stimulation of an EGS, fluid can be injected into a fault zone or into the rock matrix containing pre-existing faults adjacent to the injection well. The differences in hydromechanical responses between fluid injection into and adjacent to a fault have not been investigated in detail. Here, we performed triaxial fluid injection experiments involving injecting fluid directly and indirectly into a fault in granite rock samples to analyse the distinct hydromechanical responses and estimate the injection-induced seismicity in both cases. Our results suggest that in addition to directly injecting fluid into a critically stressed fault, injecting into nearly intact granite adjacent to the fault could also cause injection-induced seismic hazards owing to the high fluid pressure required to create new fractures in the granite matrix. It is, therefore, important to carefully identify pre-existing faults within tight reservoirs to avoid injecting fluid adjacent to them. Additionally, once prior unknown faults are delineated during hydraulic stimulation, appropriate shut-in strategies should be implemented immediately to mitigate seismic risks. This article is part of the theme issue 'Induced seismicity in coupled subsurface systems'. [ABSTRACT FROM AUTHOR]

Injection-induced seismicity and aseismic slip often involve the reactivation of long-dormant faults, which may have extremely low permeability prior to slip. In contrast, most previous models of fluid-driven aseismic slip have assumed linear pressure diffusion in a fault zone of constant permeability and porosity. Slip occurs within a frictional shear crack whose edge can either lag or lead pressure diffusion, depending on the dimensionless stress-injection parameter that quantifies the prestress and injection conditions. Here, we extend this foundational work by accounting for permeability enhancement and dilatancy, assumed to occur instantaneously upon the onset of slip. The fault zone ahead of the crack is assumed to be impermeable, so fluid flow and pressure diffusion are confined to the interior, slipped part of the crack. The confinement of flow increases the pressurization rate and reduction of fault strength, facilitating crack growth even for severely understressed faults. Suctions from dilatancy slow crack growth, preventing propagation beyond the hydraulic diffusion length. Our new two-dimensional and three-dimensional solutions can facilitate the interpretation of induced seismicity data sets. They are especially relevant for faults in initially low permeability formations, such as shale layers serving as caprock seals for geologic carbon storage, or for hydraulic stimulation of geothermal reservoirs. This article is part of the theme issue 'Induced seismicity in coupled subsurface systems'. [ABSTRACT FROM AUTHOR]

We consider the stability of the global weak solution of the Quantum Euler system in two space dimensions. More precisely, we establish compactness properties of global finite energy weak solution for large initial data provided that these are axisymmetric. The main novelty is that the initial velocity is not necessary irrotational when the density is not vanishing, our main argument is based on the Madelung transform which enables us to prove new Kato estimates on the irrotational part of the velocity. [ABSTRACT FROM AUTHOR]

Coiled tubing endures significant pressure and fluid impact throughout the oil and gas production and transportation processes. The abrasive action of sand-carrying liquids against the pipe wall leads to gradual thinning, compromising its ability to bear pressure and tension, ultimately resulting in fractures and leaks. To address this concern, this study conducts liquid–solid two-phase steady-state erosion experiments on coiled tubing flushed with sand-carrying liquids. The experiments choose CT110, TS110 and QT1100 tubing samples, explore various particle properties, fluid factors, and pipeline conditions to investigate the thinning rate caused by erosion. The CT110 coiled tubing exhibits a higher erosion rate when subjected to sand-laden fluid erosion in the experiment. This characteristic proves beneficial in numerical simulations, as it allows for a more pronounced demonstration of the effectiveness of erosion prediction models under equivalent conditions. A predictive model for coiled tubing erosion and thinning has been established by incorporating erosion theory and the discrete phase model. The discrete phase model adeptly comprehends and describes the experimental phenomena associated with sand-carrying fluid erosion. By providing comprehensive experimental data and theoretical analysis, this article facilitates the prediction of the uniform thinning rate of the oil pipe wall and enables the estimation of its service life. [ABSTRACT FROM AUTHOR]

Generated rotor (gerotor) pumps have commercial applications in oil supply pumps and compressors. Unfortunately, they produce an excessive amount of noise while in operation. The present study focuses on reducing the noise, which is caused due to pressure oscillations in the fluid, and vibration levels when a gerotor pump is in operation. Three-dimensional numerical simulations were performed on the gerotor pump using the dynamic mesh method. The flow field was simulated using the commercial software Ansys Fluent. The mesh motion was provided in the form of a user-defined function. Computational fluid dynamics analysis was performed for different combinations of delivery pipe length and diameter, and their effects on delivery pressure were analyzed. It is observed from numerical results that the pressure oscillations are reduced around 20 % by increasing volume of port or pipe region, which in turn reduces the noise levels. It is concluded that the pressure oscillations during the fluid flow are highly dependent on the volume of the delivery pipe. [ABSTRACT FROM AUTHOR]

The Anninghe Fault (ANHF) is a major left‐lateral strike‐slip fault in southwestern China and one of the main seismogenic fault zones with a history of strong earthquakes. To understand the frictional properties of natural granitic gouges from the principal slip zone, we conducted hydrothermal friction experiments using both saw‐cut and ring shear methods. These experiments were performed at temperatures (T) of 25–600°C, pore pressures (Pf) of zero (dry), 30 and 100 MPa, sliding velocities (V) of 0.01–100 μm/s and effective normal stresses (σneff ${\sigma }_{\mathrm{n}}^{\text{eff}}$) of 68, 100, and 200 MPa. The (apparent) friction coefficient is low (μ < 0.5) at high T (600°C), high Pf (100 MPa) and low V (<1 μm/s); but high (μ > 0.6) under all other T, Pf and V conditions. Under high Pf, the velocity dependence of friction, (a‐b), displays three regimes with increasing temperature, from positive below ∼100°C to negative at 100–300°C (at V = 1–3 μm/s) or else 100–450°C (at V = 30–100 μm/s), becoming positive again above 300–450°C. At low Pf, the negative (a‐b) expands to the range ∼300–600°C. Microstructural observations and microphysical interpretation imply that the frictional weakening and transitions in (a‐b) are related to competition between dilatant granular flow and deformation of the fine‐grained gouge by intergranular pressure solution accompanied by healing phenomena (leading to cavitation‐creep‐like behavior). Our results provide a possible explanation for the distribution of earthquakes at different depths in the continental crust, in particular for the depth range of the seismogenic zone between 4 and 24 km along the ANHF. Plain Language Summary: The left‐lateral Anninghe Fault (ANHF), bounding the Tibetan Plateau in China, accommodates part of the distributed convergence between the Indian and Eurasian plates. It has accommodated numerous historical earthquakes during the last few centuries. However, the mechanisms controlling the frictional behavior of natural granitic fault rocks (gouges) collected from ANHF are poorly understood. Laboratory friction experiments were performed at a wide range of temperatures (T), velocities (V) and shear displacements (X), employing varying pore fluid pressure (Pf). The gouges showed potentially unstable shearing behavior at 100–450°C (corresponding to 4–18 km depth), extending up to 600°C (24 km depth) at low Pf (≤30 MPa) and low V (0.04 μm/s). Low frictional strength obtained in large displacement experiments at 600°C indicates a transition from brittle to ductile and seismic‐aseismic (velocity‐strengthening) behavior. Based on microstructural analysis and a microphysical model, we infer that the observed behavior is due to competition between brittle/frictional flow of the granular gouge and creep involving stress‐driven dissolution of the finely crushed constituent grains. Our results offer a possible explanation for the distribution of earthquakes at different depths between 4 and 24 km along the ANHF. Key Points: New experiments confirm a low friction coefficient (μ = 0.37) for granitic gouge at high temperature hydrothermal conditionsThe temperature range characterized by velocity‐weakening narrows with decreasing velocity and with increasing pore fluid pressurePressure solution is a key deformation mechanism controlling the velocity dependence of friction in fine‐grained granite gouge [ABSTRACT FROM AUTHOR]

Coseismic rupture and aftershock development on a fault plane are complex and heterogeneous processes. The Mw 6.1 L'Aquila 2009 normal faulting earthquake is a perfect case to explore how fault geometry and rheology influence the rupture process and aftershocks distribution. In this study, we use for the first time a dense set of earthquake data to obtain enhanced images of the causative normal fault structure to the kilometer scale. The hypocenter of the emergent onset of the mainshock took place within a low Vp/Vs volume, while the large coseismic slip occurred a few kilometers above, as the rupture propagated through a high Vp and high Vp/Vs fluid‐filled rock volume. The increase of Vp/Vs in the fault hanging wall during the sequence suggests a strong dehydration in the earthquake asperity, with an upward fluid pressure migration along the fault toward the host rock volume. We propose that the localization of deformation on the fault plane is favored by high fluid pressure, while the spreading of aftershocks on a wide volume around the fault is driven by the depletion of fluids from the slipped portion of the fault plane and migration to small segments within the fault host rocks. Plain Language Summary: The relationship between coseismic slip during mainshocks, aftershock distribution and fault geometry and rheology is fundamental to understanding the earthquake's nucleation process. Here, we compute high‐resolution Vp and Vp/Vs models for the L'Aquila fault ruptured in 2009 using a vast data set of aftershocks and a double‐difference tomographic method. We compare aftershock distribution with velocity anomalies on the fault plane and surrounding volume, observing that the localization of deformation on the fault plane and the dispersion of aftershocks within the host volume is favored by high fluid pressure. Transient changes of Vp and Vp/Vs during the first month of aftershocks reveal an increase of pore pressure in the upper tip of the fault and in the surrounding host rock, generated by fluid depletion in the earthquake asperity. Key Points: We used about 14,000 aftershocks to compute high‐resolution Vp and Vp/Vs models of the Mw 6.1 L'Aquila 2009 causative faultThe localization of deformation on the fault plane is favored by high fluid pressureThe depletion of fluids from the slipped portion of the fault plane drives the spreading of the aftershocks on a wide volume around the fault [ABSTRACT FROM AUTHOR]

We obtained the solutions of Einstein's Field Equations (EFEs) for locally rotationally symmetric (LRS) Bianchi type-I perfect fluid spacetimes through the concircular vector fields (CCVFs) in f (T) gravity. It is shown that such metrics admit CCVFs of 4, 5, 6, 7, 8 and 15 dimensions. We also calculated the energy density, fluid pressure, torsion scalar T and the form of the function f (T). We did not specify the form of f (T) for the solution of EFEs but found a particular form of f (T) during the process of finding the CCVFs. It is observed that energy density and fluid pressure of some solutions are related as p = − ρ , which means that the universe represented by these spacetime metrics behaves like dark energy models. For other solutions, it is observed that the fluid pressure and energy density can remain positive for particular choices of the constants involved. Thus, in these cases the rate of expansion can slow down due to positive attractive effect. We also calculated the Hubble's parameter (H), scalar expansion (), shear scalar ( σ 2 ), anisotropy parameter ( A m ) and the deceleration parameter (q) associated with each of the obtained exact LRS Bianchi type-I solutions. It is observed that the physical behavior of the spacetime changes with the number of admitting CCVFs. A constant anisotropic behavior for 15-dimensional CCVFs is observed to change to isotropic nature for seven-dimensional CCVFs. [ABSTRACT FROM AUTHOR]

Blood vessels are essential for maintaining tumor growth, progression, and metastasis, yet the tumor vasculature is under a constant state of remodeling. Since the tumor vasculature is an attractive therapeutic target, there is a need to predict the dynamic changes in intratumoral fluid pressure and velocity that occur across the tumor microenvironment (TME). The goal of this study was to obtain insight into perfusion anisotropy within lung tumors. To achieve this goal, we used the perfusion marker Hoechst 33342 and vascular endothelial marker CD31 to stain tumor sections from C57BL/6 mice harboring Lewis lung carcinoma tumors on their flank. Vasculature, capillary diameter, and permeability distribution were extracted at different time points along the tumor growth curve. A computational model was generated by applying a unique modeling approach based on the smeared physical fields (Kojic Transport Model, KTM). KTM predicts spatial and temporal changes in intratumoral pressure and fluid velocity within the growing tumor. Anisotropic perfusion occurs within two domains: capillary and extracellular space. Anisotropy in tumor structure causes the nonuniform distribution of pressure and fluid velocity. These results provide insights regarding local vascular distribution for optimal drug dosing and delivery to better predict distribution and duration of retention within the TME. [ABSTRACT FROM AUTHOR]

Linear surface gravity wave scattering by a partial porous breakwater is studied in a two-layer ocean having an interface with bottom undulations. The partial breakwaters, namely surface-piercing breakwater (SPB) and bottom-standing breakwater (BSB), are considered. The continuity of fluid pressure and mass flux is applied at interface boundaries, while mass conserving conditions are employed to account for slope discontinuity in seabed geometry. Porous breakwaters' reflective and dissipative characteristics are studied under wave-wave interaction. The study reveals that when a mound bottom is present, more incident waves in interface mode are transmitted through BSB, while more waves in surface mode are dissipated. More incident waves in surface mode are transmitted through SPB, while more waves in interface mode are dissipated. In contrast, more transmission occurs in surface mode through both BSB and SPB for a slope-shelf bottom. However, the breakwater dissipates a substantial amount of incident-wave energy in interface mode. Further, a considerable reduction in wave transmission occurs due to higher reflection by the interface-piercing porous breakwaters, and the breakwaters experience high wave loads. Relatively, porous breakwater dissipates less wave energy in shallow depth. The study reveals that the dead water effect is weakened by the porous breakwater. [ABSTRACT FROM AUTHOR]

Patchy saturation is a term used in the seismic prospecting literature to describe the state of a geological formation in which two immiscible pore fluids prevail in mesoscopic-scale clusters. If the pore fluids have contrasting compressibilities, wave-induced fluid pressure diffusion (FPD) processes may induce significant attenuation and velocity dispersion on seismic waves. Biot's monophasic poroelasticity theory is widely used to model the seismic response of rocks containing binary patches of two immiscible pore fluids. Even though effective fluid approximations may help to represent more realistic partially saturated patches using Biot's monophasic equations, the so inferred dissipation may not be representative of actual biphasic FPD phenomena. In this work, Biot's equations for mono- and biphasic fluids are combined to model FPD processes in porous media, comprising fully and partially saturated patches. An analytical solution for one-dimensional layered patchy-saturated media is presented which permits to explain some, as of yet enigmatic, experimentally observed characteristics such as increased seismic attenuation and stiffening effects occurring at low saturations. The results show that the existence of an additional diffusive wave mode within partially saturated patches may render conventional binary and effective fluid approaches incorrect and error prone. [ABSTRACT FROM AUTHOR]