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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]

• A novel three-equation two-phase flow model is proposed for sedimentation and consolidation. • Fluid pressure increases with initial sediment concentration, necessitating incorporation of non-hydrostatic pressure. • Inertial effects become significant with larger grains, indicating the need to incorporate inertial forces. Sedimentation and consolidation, a multi-physical phenomenon of great significance in aquatic environments, usually involves dynamic pore pressure, inertial effects, fluid-particle interphase interaction and solid stress. However, simplified models for sedimentation and consolidation typically assume hydrostatic mixture pressure and neglect inertial effects without proper justifications. Here, a one-dimensional three-equation two-phase flow model (TTP) is proposed for sedimentation and consolidation, which directly resolves dynamic fluid pressure and inertial terms. The present TTP model is benchmarked against a series of experimental cases and two existing four-equation two-phase flow (FTP) models. It features encouraging performance as compared to measured data and computed results of the existing FTP model. Furthermore, the present TTP model shows superior computing efficiency over the FTP models. To investigate the influences of inertial effects and non-hydrostatic mixture pressure, two simplified versions of the TTP model are constructed and compared with the TTP model. It is shown that incorporating inertial effects and non-hydrostatic fluid pressure are important for accurately predicting the sedimentation-consolidation process. The present study facilitates a promising framework for modelling sedimentation and consolidation, thereby supporting effective sediment management. [ABSTRACT FROM AUTHOR]

Ferroptosis-related tumor therapy based on nanomedicines has recently gained significant attention. However, the therapeutic performance is still hindered by the tumor's physical barriers such as the fibrotic tumor matrix and elevated interstitial fluid pressure, as well as chemical barriers like glutathione (GSH) overabundance. These physicochemical barriers impede the bioavailability of nanomedicines and compromise the therapeutic efficacy of lipid reactive oxygen species (ROS). Thus, this study pioneers a manganese-mediated overcoming of physicochemical barriers in the tumor microenvironment using organosilica-based nanomedicine (MMONs), which bolsters the synergy of photothermal-ferroptosis treatment. The MMONs display commendable proficiency in overcoming tumor physical barriers, due to their MnO 2 -mediated shape-morphing and softness-transformation ability, which facilitates augmented cellular internalization, enhanced tumor accumulation, and superior drug penetration. Also, the MMONs possess excellent capability in chemical barrier overcoming, including MnO 2 -mediated dual GSH clearance and enhanced ROS generation, which facilitates ferroptosis and heat shock protein inhibition. Notably, the resulting integration of physical and chemical barrier overcoming leads to amplified photothermal-ferroptosis synergistic tumor therapy both in vitro and in vivo. Accordingly, the comparative proteomic analysis has identified promoted ferroptosis with a transient inhibitory response observed in the mitochondria. This research aims to improve treatment strategies to better fight the complex defenses of tumors. Preparation of a mesoporous organosilica/manganese dioxide nanomedicine (MMONs) for enhanced in vitro and in vivo photothermal-ferroptosis synergistic antitumor efficacy via manganese-mediated overcoming of physicochemical barriers in tumor microenvironment. [Display omitted] [ABSTRACT FROM AUTHOR]

Owing to the dense extracellular matrix and high interstitial fluid pressure in the tumor microenvironment, methods which enhance the permeation and retention of nano drugs into liver tumors remain unsatisfactory for successful tumor treatment. We designed a near-infrared (NIR)- and ultrasound (US)-triggered Pt/Pd-engineered "cluster bomb" (Pt/Pd-CB) which actively penetrates liver cancer cell membranes and achieves photothermal and sonodynamic therapy (SDT). The physical forces generated by the fast expansion and collapse of perfluoropentane nanodroplets eject "sub bombs" (Pt/Pd nanoalloys) into liver cancer cells upon activation by NIR and US. Pt/Pd nanoalloys can then convert H 2 O 2 into O 2 to alleviate hypoxia and boost SDT efficiency while exhibiting a highly efficient photothermal response under NIR irradiation. Our findings might especially be promising for the treatment of solid tumors. [Display omitted] [ABSTRACT FROM AUTHOR]

Histological and micro-ultrasound evidence rebuffs deep-rooted views on the nature of nerve block, nerve damage, and injection pressure monitoring. We propose that the ideal position of the needle tip for nerve block is between the innermost circumneural fascial layer and outer epineurium, with local anaesthetic passing circumferentially through adipose tissue. Thin, circumferential, subepineural expansion that is invisible to the naked eye was identified using micro-ultrasound, and could account for variability of outcomes in clinical practice. Pressure monitoring cannot differentiate between intrafascicular and extrafascicular injection. High injection pressure only indicates intraneural extrafascicular spread, not intrafascicular spread, because it is not possible to inject into the stiff endoneurium in most human nerves. [ABSTRACT FROM AUTHOR]

While most of current models investigating bone remodelling are based on matrix deformation, intramedullary pressure also plays a role. Bone remodelling is orchestrated by the Lacuno-Canalicular Network (LCN) fluid-flow. The aim of this review was hence to assess the influence of intramedullary pressure on the fluid circulation within the LCN. Three databases (Science Direct, Web of Science, and PubMed) were used. The first phase of the search returned 731 articles, of which 9 respected the inclusion/exclusion criteria and were included. These studies confirm the association between intramedullary pressure and fluid dynamics in the LCN. Among the included studies, 7 experimental studies using animal models and 2 numerical models were found. The studies were then ranked according to the nature of the applied loading, either axial compression or direct cyclic intramedullary pressure. The current review revealed that there is an influence of intramedullary pressure on LCN fluid dynamics and that this influence depends on the magnitude and the frequency of the applied pressure. Two studies confirmed that the influence was effective even without bone matrix deformation. While intramedullary pressure is closely associated with LCN fluid, there is a severe lack of studies on this topic. Since the 1990's, numerical models developed to investigate fluid flow in bone submicrometric porous network are based on the flow induced by matrix deformation. Bone fluid flow is known to be involved in cells stimulation and hence directly influences bone remodeling. Different studies have shown that intramedullary pressure is also associated with bone mechanosensitive adaptation. This pressure is developed in bone due to blood circulation and is increased during loading or muscle stimulation. The current article reviews the studies investigating the influence of this pressure on bone porous fluid flow. They show that fluid flow is involved by this pressure even without bone matrix deformation. The current review article highlights the severe lack of studies about this mechanism. [Display omitted] [ABSTRACT FROM AUTHOR]

We present a finite element discretization to model the interaction between a poroelastic structure and an elastic medium. The consolidation problem considers fully coupled deformations across an interface, ensuring continuity of displacement and total traction, as well as no-flux for the fluid phase. Our formulation of the poroelasticity equations incorporates displacement, fluid pressure, and total pressure, while the elasticity equations adopt a displacement-pressure formulation. Notably, the transmission conditions at the interface are enforced without the need for Lagrange multipliers. We demonstrate the stability and convergence of the divergence-conforming finite element method across various polynomial degrees. The a priori error bounds remain robust, even when considering large variations in intricate model parameters such as Lamé constants, permeability, and storativity coefficient. To enhance computational efficiency and reliability, we develop residual-based a posteriori error estimators that are independent of the aforementioned coefficients. Additionally, we devise parameter-robust and optimal block diagonal preconditioners. Through numerical examples, including adaptive scenarios, we illustrate the scheme's properties such as convergence and parameter robustness. [ABSTRACT FROM AUTHOR]

A linearized fully discrete Crank-Nicolson finite element scheme is proposed for solving the three-dimensional incompressible magnetohydrodynamic equations based on a magnetic vector potential formulation, where the magnetic induction is written to a rotation of magnetic vector potential. By using the MINI element and lowest order Nédélec edge element to approximate the velocity field and pressure of fluid and magnetic vector potential, respectively, the numerical solution of magnetic induction can preserve the exactly divergence-free condition in fully discrete level. Error estimates for the velocity field and magnetic vector potential are rigorously analyzed under some reasonable regularity assumptions of exact solution. Finally, numerical results are given to support the theoretical analysis. [ABSTRACT FROM AUTHOR]

[Display omitted] The annulus fibrosus (AF), a permeable, hydrated, and fiber-reinforced soft tissue, exhibits complex responses influenced by fluid pressure, osmotic pressure, and structural mechanics. Existing models struggle to comprehensively represent these intricate interactions and the heterogeneous solid responses within the AF. Additionally, the mechanisms driving differential damage accumulation between non-degenerative and degenerative intervertebral discs remain poorly understood. In this study, we introduce a biphasic-swelling damage model for the AF. We conceptually develop and rigorously validate this model through tissue-level tests employing various loading modes, consistently aligning model predictions with experimental data. Leveraging parametric geometric algorithms and custom Python scripts, we construct models simulating both non-degenerative and degenerative discs. Following calibration, we subject these models to viscous loading protocols. Our findings reveal the posterior AF's susceptibility to damage, contingent upon loading rate and water content. We elucidate the underlying mechanisms by examining the temporal evolution of fluid pressure, osmotic pressure, and the regionally dependent fiber network. This research presents a highly accurate model of the AF, providing valuable insights into disc damage. Future research endeavors should expand this model to incorporate ionic transport and diffusion, enabling a more profound exploration of intervertebral disc mechanobiology. This comprehensive model contributes to a better understanding of AF behavior and may inform therapeutic strategies for disc-related pathologies. This research presents a comprehensive model of the annulus fibrosus (AF), a crucial component of the intervertebral disc that provides structural support and resists deformation. The study introduces a biphasic-swelling damage model for the AF and validates it through tissue-level tests. The model accounts for fluid pressure, osmotic pressure, and matrix mechanics, providing a more accurate representation of the AF's behavior. The study also investigates the differential damage accumulation between non-degenerative and degenerative discs, shedding light on the mechanisms driving disc degeneration. The findings have significant implications for medical treatments and interventions, as they highlight the posterior AF's susceptibility to damage. This research is of great interest to readers interested in biomechanics, tissue engineering, and medical treatments for disc degeneration. [ABSTRACT FROM AUTHOR]

Idiopathic normal pressure hydrocephalus (iNPH) is a neurological disorder characterized by the triad of gait disturbance, cognitive impairment, and urinary incontinence. The condition is diagnosed mainly in older adults and is associated with ventricular enlargement without an increase in cerebrospinal fluid pressure. The clinical assessment involves a detailed medical history, physical examination, and cognitive testing. Neuroimaging is an essential part of the diagnostic workup for iNPH. However, to determine the suitability of patients for shunt surgery, a range of invasive preoperative investigations are employed. This narrative review aims to provide a comprehensive analysis of the current literature on invasive preoperative investigations in iNPH, focusing primarily on the lumbar infusion test, cerebrospinal fluid drainage tests, and continuous intracranial pressure monitoring. The strengths and limitations of each method, as well as their potential impact on treatment outcomes, are discussed. [ABSTRACT FROM AUTHOR]

In tests of marine hydrate depressurization production in many countries, accidents such as collapse and failure of boreholes have occurred, which caused by the evolution of the effective stress field have motivated further attention. However, in existing effective stress models, the pressure of the fluid in the wellbore is taken as the boundary condition, which did not account for the effects of the wellbore on the effective stress distribution. This paper is aimed at proposing a methodology to research the spatio-temporal evolution of the effective stress during the hydrate depressurization production, in order to provide a theoretical benchmark against which to analyze the borehole stability. We derived a mathematical model of the effective stress by taking into account the interaction between the wellbore and the reservoir on the basis of the theory of elasticity, and coupled with deposited infiltration using fluid-structure interaction theory, a coupled multiple field model considering the kinetic effects of hydrate decomposition was then established. And a solver was developed independently. A case study shows that the wellbore has significant effect on the effective stress within the radius of 0.5 m of the reservoir. At the borehole wall, the radial effective stress is 23.58 MPa, whereas the circumferential effective stress is 7.31 MPa, such nonuniformity of the effective stress lead to the risk of borehole failure. As the production progresses, the effective stress increases rapidly at first and then slowly. The effective stress is slightly affected by the size of the wellbore, it is found that when the outside diameter of the wellbore is increased from 100 mm to 500 mm, the change is less than 3.04 %. [Display omitted] • A novel methodology to research the evolution of effective stress was proposed. • A multi-field coupled analytical model of effective stress was established. • The evolution of effective stress during hydrate depressurization was revealed. • The influence of geological factors on the effective stress was identified. [ABSTRACT FROM AUTHOR]

• A novel study on pressure exchanger for use in commercial refrigeration. • CFD based thermodynamic investigation. • Pressure lift correlation developed for thermodynamic study. • Performance superiority over ejector system analysed. • Significant energy savings over parallel compression system. This manuscript presents a method to thermodynamically model a pressure exchanger device. CFD-based model of a rotary energy recovery device used in desalination process is developed and validated with published experimental data with a maximum deviation of 5.19%. The dimensionality of the validated model was reduced to investigate the potential of the pressure exchanger device operating with CO 2 as the working fluid. Based on the data obtained from several numerical experiments, two correlations were developed, by means of non-linear regression analysis, for estimating the pressure lift generated by the device as a function of inlet velocity of high pressure fluid (0.5 – 3 m/s), rotor speed (500 – 3000 rpm), receiver pressure (25 – 40 bar) and gas-cooler pressure (90 – 120 bar). The correlations were found to be within acceptable error margin. The pressure lift generated by the pressure exchanger was found to be directly proportional to the inlet velocity of the high pressure fluid and inverse proportionality to the rotor speed. The developed correlations are used to evaluate the thermodynamic performance of a multi evaporator supermarket refrigeration system integrated with pressure exchanger to a conventional parallel compression system and a published multi-ejector system in the ambient temperature range of 30 to 40 °C. The pressure exchanger based system was found to outperform the parallel compression as well as the multi-ejector system and demonstrate significant energy savings. [ABSTRACT FROM AUTHOR]

• A two-scale computational approach incorporating the influence of surface topography is developed. • The macroscopic flow problem is formulated by using finite-difference partial derivatives of flow fluxes. • The linearization method is presented for the solution to the macroscopic flow problem. • A homogenization procedure of microscopic simulations is described. • Near-periodic boundary conditions are modelled at the microscopic domain for the two-scale coupling mechanism. In the work, a novel two-scale computational approach aiming to provide the homogenized behavior informed by microscale computations is developed for hydrodynamically lubricated slider bearing. A derivative formulation with respect to main lubricated parameters is derived to calculate the fluid pressure at the macroscopic domain. Partial derivative terms included in this formulation are calculated by employing the linearization method presented, where flow fluxes obtained at the microscopic domain are averaged using homogenization technique. On the basis of pressure shift and mass conservation principle, the near-periodic boundary conditions are modelled for exactly describing the fluid behavior at the microscopic domain. A series of numerical simulations are implemented for evaluating the impacts of the topography shape, the topography amplitude, and the topography wavelength on bearing characteristics. [ABSTRACT FROM AUTHOR]

In order to achieve targeted delivery of anticancer drugs, efficacy improvement, and side effect reduction, various types of nanoparticles are employed. However, their therapeutic effects are not ideal. This phenomenon is caused by tumor microenvironment abnormalities such as abnormal blood vessels, elevated interstitial fluid pressure, and dense extracellular matrix that affect nanoparticle penetration into the tumor's interstitium. Furthermore, nanoparticle properties including size, charge, and shape affect nanoparticle transport into tumors. This review comprehensively goes over the factors hindering nanoparticle penetration into tumors and describes methods for improving nanoparticle distribution by remodeling the tumor microenvironment and optimizing nanoparticle physicochemical properties. Finally, a critical analysis of future development of nanodrug delivery in oncology is further discussed. This article reviews the factors that hinder the distribution of nanoparticles in tumors, and describes existing methods and approaches for improving the tumor accumulation from the aspects of remodeling the tumor microenvironment and optimizing the properties of nanoparticles. The description of the existing methods and approaches is followed by highlighting their advantages and disadvantages and put forward possible directions for the future researches. At last, the challenges of improving tumor accumulation in nanomedicines design were also discussed. This review will be of great interest to the broad readers who are committed to delivering nanomedicine for cancer treatment. [Display omitted] [ABSTRACT FROM AUTHOR]

Recent in vivo and in vitro studies have demonstrated that superficial zone (SZ) chondrocytes within articular layers of diarthrodial joints die under normal physiologic loading conditions. In order to further explore the implications of this observation in future investigations, we first needed to understand the mechanical environment of SZ chondrocytes that might cause them to die under physiological sliding contact conditions. In this study we performed a multiscale finite element analysis of articular contact to track the temporal evolution of a SZ chondrocyte's interstitial fluid pressure, hydraulic permeability, and volume under physiologic loading conditions. The effect of the pericellular matrix modulus and permeability was parametrically investigated. Results showed that SZ chondrocytes can lose ninety percent of their intracellular fluid after several hours of intermittent or continuous contact loading, resulting in a reduction of intracellular hydraulic permeability by more than three orders of magnitude. These findings are consistent with loss of cell viability due to the impediment of cellular metabolic pathways induced by the loss of fluid. They suggest that there is a simple mechanical explanation for the vulnerability of SZ chondrocytes to sustained physiological loading conditions. Future studies will focus on validating these specific findings experimentally. As with any mechanical system, normal 'wear and tear' of cartilage tissue lining joints is expected. Yet incidences of osteoarthritis are uncommon in individuals younger than 45. This counter-intuitive observation suggests there must be an intrinsic repair mechanism compensating for this wear and tear over many decades of life. Recent experimental studies have shown superficial zone chondrocytes die under physiologic loading conditions, suggesting that this repair mechanism may involve cell replenishment. To better understand the mechanical environment of these cells, we performed a multiscale computational analysis of articular contact under loading. Results indicated that normal activities like walking or standing can induce significant loss of intracellular fluid volume, potentially hindering metabolic activity and fluid transport properties, and causing cell death. [Display omitted] [ABSTRACT FROM AUTHOR]

For the simulation of fluid–structure interaction (FSI) problems, the monolithic method provides more robust convergence than the partitioned method but requires solving a larger matrix for a saddle-point problem that is difficult to precondition. We extend the existing semi-implicit method to propose a new semi-monolithic method for FSI simulation that uses a velocity boundary equation of a pressure Poisson equation so that only the pressure variables of the fluid domain are coupled with the displacement variables of the solid domain in a monolithic manner. The fluid domain is solved by employing a fractional four-step method for the incompressible Navier–Stokes equations based on an arbitrary Lagrangian–Eulerian (ALE) formulation, and the solid domain is solved by an updated Lagrangian method for simulating large nonlinear deformations. We applied the proposed method to 2D/3D benchmark problems with various time steps and density ratios, and the results confirmed that FSI problems with not only a strong added-mass effect but also a large deformation are simulated well. The proposed method is faster than the existing monolithic method because it solves a smaller matrix whose diagonal blocks are diagonally dominant matrices, which are much easier to precondition. • A new semi-monolithic formulation for FSI problems is proposed. • Fluid domain is solved by ALE based on the incompressible Navier–Stokes equations. • Solid domain is solved by updated Lagrangian method for nonlinear large deformation. • The method can simulate FSI with a strong added-mass effect and a large deformation. • The method is faster than an existing monolithic method requiring less memory. [ABSTRACT FROM AUTHOR]

Temporal lobe changes, such as anterior temporal lobe meningoceles or encephaloceles, have been documented as possible epileptogenic foci in a subset of pediatric patients with seizures. In our study, we aim to analyze a different structural change in the temporal lobe, remodeling of the posterior temporal skull base by the inferior temporal gyrus called the "temporal thumb sign" (TTS), in pediatric patients presenting with new-onset seizures with or without elevated opening pressure (OP), patients presenting with confirmed diagnosis of idiopathic intracranial hypertension (IIH) without seizure presentation, and healthy controls. Magnetic resonance imaging scans of 163 pediatric patients were studied retrospectively for the presence of TTS. We analyzed the scans of 43 patients with elevated OP and confirmed IIH, 40 patients with elevated OP and new-onset idiopathic seizures, 40 patients with normal OP and new-onset idiopathic seizures, and 40 age- and sex-matched healthy controls. The TTS was detected most frequently in patients with elevated OP and seizures at 72.5% compared with patients with IIH with no seizures and patients with normal OP and seizures (32.6% and 27.5%, respectively). The TTS had a frequency of 12.5% in the control group. The TTS had the highest combination of specificity and sensitivity (72.5% and 72.5%) in patients with seizures and elevated OP compared with patients with seizures and normal OP (P value < 0.001). Our results suggest the Kamali "temporal thumb sign" is a novel imaging feature that may be used as a sensitive and specific imaging finding associated with seizures and elevated OP in the pediatric population. [ABSTRACT FROM AUTHOR]

Fluid pressurization rate is an important inducement to fracture slip. In order to characterize the fracture slip initiation and slip mode during fluid pressurization, a series of stepwise injection induced shear tests were carried out. Results show that fracture slip initiation depends on fluid pressure and roughness of fracture surface. Fluid pressurization rate, fluid pressure non– uniform distribution all affect fracture slip initiation. Reducing fluid pressurization rate seems cannot effectively avoid induced earthquake, but can delay the time and scale of induced earthquake, especially can alleviate induced earthquake after shut-in. Earthquake induced after shut-in may be caused by secondary damage of concave-convex body on fault surface under the action of fluctuating pressure generated from injection wells or underground water sources around fault. Furthermore, a new view is proposed that the change of fluid pressure gradient on fracture surface is an important complementary mechanism for shut-in induced earthquakes. [ABSTRACT FROM AUTHOR]

Hydrogen can act as an energy store to balance supply and demand in the renewable energy sector. Hydrogen storage in subsurface porous media could deliver high storage capacities but the volume of recoverable hydrogen is unknown. We imaged the displacement and capillary trapping of hydrogen by brine in a Clashach sandstone core at 2–7 MPa pore fluid pressure using X-ray computed microtomography. Hydrogen saturation obtained during drainage at capillary numbers of <10−7 was ∼50% of the pore volume and independent of the pore fluid pressure. Hydrogen recovery during secondary imbibition at a capillary number of 2.4 × 10−6 systematically decreased with pressure, with 80%, 78% and 57% of the initial hydrogen recovered at 2, 5 and 7 MPa, respectively. Injection of brine at increasing capillary numbers up to 9.4 × 10−6 increased hydrogen recovery. Based on these results, we recommend more shallow, lower pressure sites for future hydrogen storage operations in porous media. • Hydrogen injectivity and recovery in rock is imaged with x-ray computed micro-CT. • Hydrogen recovery decreases with increasing reservoir depth. • Hydrogen recovery increases with increasing brine flow rate. • Hydrogen trapping occurs via snap-off processes. • Nitrogen is a poor proxy for hydrogen. [ABSTRACT FROM AUTHOR]

Understanding the fluid flow and heat transfer process in the well-fracture-reservoir combined system is crucial for the development of Enhanced or Engineered Geothermal Systems (EGS). In this paper, a well-fracture-reservoir integrated numerical model is developed to study the heat extraction performance considering the interactions among the well boreholes, the fractures in the reservoir and the base rock reservoir itself. The wells and major fractures are precisely described by the direct modelling while the sub-fractures in the base rock are described by a permeability distribution. A novel method to improve the heat extraction performance of EGS by enhancing the permeability in the near-well region is proposed. Simulation results show that the fluid flow path is predominantly determined by the well layout and fracture network. The fluid pressure is non-linearly distributed between the injection and production wells in the fractures and reservoir. Further, an optimized scheme for heat extraction of an assumed geothermal site in Gonghe Basin is proposed based on the near-well enhancement approach. The overall heat extraction performance of the near-well enhanced case is improved by more than 15.0%. The present work provides a feasible improvement scheme for EGS to achieve a better heat extraction performance. [ABSTRACT FROM AUTHOR]

This study was meant to describe a Poloxamer hydrogel combining Chitosan- N -acetyl-L-cysteine (CNAC) nanoparticles to increase loading and sustained intravitreal administration of Avastin macromolecule. To increase the drug's efficacy and reduce the interfacial fluid pressure in a formulation, dexamethasone was used. To do so, CNAC was synthesized. Then, Avastin- loaded CNAC nanoparticles were prepared and optimized. The resulting hydrogel's sol-gel transition time and viscosity were determined using poloxamer and hydroxypropylmethylcellulose (HPMC). In vitro and in vivo investigations of Avastin-loaded CNAC nanoparticles and hydrogel comprising dexamethasone/Avastin-loaded CNAC nanoparticles were determined. In vitro, the drug release profile of optimized hydrogel containing Avastin-loaded CNAC nanoparticles was sustained and controlled over 256 h. The obtained results point to poloxamer/HPMC (18 %/0.5 %) as the best formulations for this hydrogel to develop a sol-gel transition. About 97 % of dexamethasone was released from the hydrogel within 18 h. In vivo results indicated that the optimized formulation compared with free Avastin could improve Diabetic retinopathy (DR). Consequently, we infer that this new drug delivery method may enhance Avastin intravitreal administration, lowering the frequency, danger, and expense of heavy intravitreal injections and resulting in improved treatment of posterior eye segment neovascularization and concomitant vitreoretinal disorders. [Display omitted] [ABSTRACT FROM AUTHOR]

We use 2-D numerical models to explore slip and stress dynamics in a fault-bound dilational jog, informed by a field example from the Dun Mountain Ophiolite in New Zealand. The jog is hosted in a metre-scale phacoid of massive serpentinite embedded in a "block-in-matrix" creeping serpentinite shear zone. The models show how periodic exceedance of the tensile strength of the contact between the sealed jog and host rock leads to episodic opening and deposition of a new crack-seal band, with a thickness limited by the release of stress around the tips of the stepover-bounding faults. Jog stress release in the model is lower than that predicted from linear elastic fracture mechanics because additional crack opening can occur slowly due to post-failure creep on the bounding faults. For 10 km overburden and constant high fluid pressure, we predict event stress release of ca. 16 MPa and total crack opening of ∼22 μm on either side of the jog, consistent with crack-seal band widths in the field example. Because our models show that total crack width reflects both initial cracking and subsequent creep, we suggest caution when using crack-seal band widths to directly infer stress release in similar shear zone settings. [Display omitted] • Numerical model of dilational jog with repeated crack-seal events. • Jog stress release depends on crack width, background stress, and tensile strength. • Crack width increases after failure via continued creep along bounding faults. • Far-field driving stress is much lower than maximum jog stress release. • Crack width can be larger than computed from simple linear elastic mechanics theory. [ABSTRACT FROM AUTHOR]

• The impact of pressure-dependent factor on crude oil cracking at high pressure conditions was investigated. • The produced fluids as pressure medium conduct a series of effects on crude oil cracking. • The relationship between fluid phase behaviours and pressure influences was elucidated. • Fluid pressure controls the occurrence of multi-phases oil and the accumulation of light oil and condensate in pores. An oil with an initial equivalent maturity of 0.74 % R o, was pyrolyzed in a closed gold tube pyrolysis system with added silica sand and no added water under simulated conditions spanning 0.7 %–2.1 % EasyRo. The internal fluid pressure, ranging from 0 to >150 MPa at individual maturities states of 1.0 %, 1.5 % and 2.1 % EasyRo, was controlled by increasing sample mass and setting external confining pressure (50, 100 and 150 MPa). Results indicate that the increasing fluid pressure initially promoted and then gradually retarded crude oil cracking. The free-radical reaction mechanism (hydrogen radical supply), free space of vessels, and characteristics of pressure medium control the influence of fluid pressure on the chemical reaction process. The decreasing free space of volume-constant vessels and the difference of hydrogen radicals supplied in various thermal maturity stages together gradually reduce the reaction rate of crude oil cracking. Thus, the yields of methane, wet gas, and light and heavy hydrocarbons increase at low fluid pressure ranges and then decrease at high-pressure conditions. Moreover, the physical controls of fluid phase behaviors include the evolution of fluid phase states influencing the increased rates of fluid pressure and fluid pressure influencing the production of multi-phase hydrocarbons. The increase in fluid pressure is faster in the saturated gas–liquid phase than in the unsaturated phase; thus, the phase behaviors induce the yields of product change. The increasing fluid pressure induces the occurrence of multi-phase hydrocarbons and accumulation of light oil and condensate. This study introduces a novel approach to investigate the influence of fluid pressure on reservoir oil cracking, emphasising phase behavior analysis, and shedding light on the evolution of organic matter in deep and ultra-deep strata. [ABSTRACT FROM AUTHOR]

A robust hydraulic system is necessary for industrial gluing equipment in order to transfer and regulate a variety of chemical fluid media. Certain operational conditions call for a certain flow output. In hydraulic systems, pressure reduction valves are frequently employed to regulate flow and pressure output. In order to analyze the flow of high viscosity special media inside the valve body, a colloidal medium that complies with the power-law constitutive law and a novel type of pressure-reducing valve appropriate for high viscosity fluids were chosen as the research objects in this study. First, the valve channel's flow performance and flow field characteristics were researched with a combination of simulation and experiments. Then the impact of pressure differences, opening, and temperature variations on flow rate was investigated. The proposed flow prediction formulas can be used to forecast the flow rate in engineering applications accurately which is verified by the comparison of the numerical and experimental results. Lastly, an analysis was done on the pressure reducing valve's capacity to regulate pressure under various operating circumstances. The research can offer a specific reference for the analysis of flow field characteristics inside valves in high viscosity media and the design of pressure-reducing valve bodies in non-Newtonian media. Furthermore, the research results can help determine whether the pressure reducing valve's operating condition is normal. • The fluid characteristics of valve body in power law fluid medium were studied. • The effects of pressure difference, opening and drinking temperature on flow rate were investigated. • An accurate and fast flow prediction equation is proposed. [ABSTRACT FROM AUTHOR]

The Callovo-Oxfordian (COx) claystone is selected as the host rock in the French project for geological disposal of radioactive waste. In its initial state, the host rock is fully saturated. Due to the low permeability, the pore fluid pressure can locally evolve in a quasi undrained condition due to subsequent mechanical and thermal loading, and then significantly affects deformation and cracking process of geological barrier. Most previous studies were carried out in quasi drained conditions or with constant pore pressure. Poromechanical behavior of COx claystone in undrained condition has been so far rarely investigated. In the present work, we carry out a new series of laboratory tests. Two representative loading paths are considered: triaxial compression with constant confining pressure and triaxial extension with constant mean stress. The variations of strain and pore pressure are measured during the tests. It is found that the poromechanical behavior of the claystone is clearly affected by loading path. The failure strength is higher in triaxial compression than in extension. The evolution of pore fluid pressure is correlated with volumetric strain. Compared with the results obtained in drained tests, it seems that the Terzaghi effective stress can be used for the description of pore fluid pressure effect on failure strength. [ABSTRACT FROM AUTHOR]

Flow boiling instability stands as one of the key factors hindering the engineering application of large-area heat sinks with parallel multi-minichannels. In this study, a novel large-area heat sink with one inlet and two outlets was fabricated with aluminum alloy. It included 50 parallel minichannels, which were interconnected by the micro-slots arrays to balance the fluid pressure and redistribute the two-phase flow during flow boiling. The working fluid selected for the study was R134a, upon which flow boiling experiments were subsequently carried out. The effects of the thermal-hydraulic parameters, such as pressure drop across the test section, inlet and outlet pressures, and wall temperatures, on the two-phase flow state during flow boiling were analyzed. The flow boiling instability criterion for large-area parallel multi-minichannels heat sink was proposed, and the flow instability map was created to predict the two-phase flow state. It was found that the ratio of heat flux to mass flux (q w / G) was an important parameter for stable and unstable two-phase flow. The flow boiling instability first locally appeared in the region near the outlet and then expanded to the entirety of the heat sink's flow passage with the escalation of the q w / G ratio. In addition, the characteristics of heat transfer and the transitions in flow patterns during flow boiling instability were also discussed. [ABSTRACT FROM AUTHOR]

This paper presents a new algorithm using physics-informed neural networks (PINNs) to track and characterize spatio-temporally varying chemical sources based on time-resolved measurements of chemical concentration, fluid velocity, and pressure. Chemical source emission functions, chemical concentration, fluid velocity and fluid pressure fields are modeled as multi-layer perceptrons (MLPs). During the training process, sensors readings of chemical concentration, fluid velocity, and fluid pressure are matched to the output of the respective MLPs at the given spatio-temporal locations. Simultaneously, the physics of fluid flow and chemical dispersion at an arbitrary number of spatio-temporal locations in the domain of interest are enforced through regularization. Once trained, the constituent MLPs can be evaluated to generate the time resolved maps of source emissions, chemical concentration, fluid velocity and pressure. Extensive numerical simulation validate the method, including scenarios with both static and dynamic sources in complex flow fields. This innovative approach marks a significant advancement in environmental monitoring technologies. • Novel physics-informed neural net (PINN) formulation for chemical source localization. • No simplifying assumptions on physics, terrain, nor parameterization of source required. • Method tested in complex 2D scenarios incorporating mobile sources with transient emissivity. [ABSTRACT FROM AUTHOR]

This study examines the influence of orientation and hardness of rubber tread blocks on friction under glycerol lubrication, focusing on negative fluid pressure. Measurements of fluid pressure, film thickness, and friction coefficient were conducted at the contact interface. Results showed that when tread blocks aligned parallel to the sliding direction, the friction coefficient increased by 57–191 %, attributed to either reduced film thickness or enlarged real contact area from greater negative fluid pressure. Conversely, with a perpendicular orientation, decreased hardness led to increased friction, due to thinner fluid films from enhanced negative pressure. [ABSTRACT FROM AUTHOR]

Oscillating wave surge converters (OWSCs) are generally of rectangular geometries. What kind of flap shape is better is still not clear. Thus, this study proposes some bionic flaps by mimicking the scallops. Eight scallop-based bionic flaps were compared. The fluid pressure and velocity surrounding the bionic and the original flaps were compared to examine why the bionic flap was better. Then, a Sobol sensitivity analysis was conducted, which found that the wave period, water depth, OWSC damping, Bezier length ratio, and Bezier height ratio have notable influences on the OWSC. Parametric study of the OWSC tells that as the increase of the Bezier length ratio, the capture factor increases first and then converges. As the increases of the remaining parameters, the capture factor increases first and then decreases. Radial basis function neural network and genetic algorithm were utilized to optimize the OWSC under different environmental conditions, and the optimized OWSC structural parameters are presented. The Bezier length ratio can always be 1.0 when in real engineering. The seaside outward curved and leeside flat bionic flap performed the best, the maximum capture factor of which is 0.48. The bionic flap improved the capture factor by 30 % compared with the original flap. • Seaside outward curved and leeside flat bionic flap is better than the original box flap. • Bezier curve is utilized to describe the geometrical shape of the flap curve. • OWSC optimizations should consider wave period, water depth, damping, Bezier curve height and length ratio. • Bezier curve length ratio should always be 1.0 to ensure that the bionic OWSC performs well. [ABSTRACT FROM AUTHOR]

Diffusion-absorption refrigeration (DAR) is a cooling technology that uses a three-component working fluid and a thermally-activated bubble-pump for fluid circulation. DAR cooling modules can be manufactured at low cost and entirely driven by thermal energy, making this a promising technology for cold-chain services in off-grid regions. In this work, we investigate the performance potential of an ammonia-water-hydrogen solar-DAR system for application in rural India. In Part I of the investigation, a semi-empirical system model is developed that considers both the steady-state operation of the DAR system and dynamic behaviour during start-up with a solar-thermal heat source. The model is calibrated using experimental data from a laboratory DAR system where heat input rate and system charge pressure are variables that can be adjusted. Under steady-state conditions, the system achieves a maximum coefficient of performance (COP) of 0.25 with a system pressure of 14 bar. However, at the minimum heat input rate of 100 W the system can take up to 2 h or longer for bubble pump activation, prior to which no cooling is produced. In the accompanying paper (Part II), the model is used to investigate the influence of various parameters on system performance and to identify promising areas for improvement. • A model of a solar diffusion absorption refrigeration system is presented. • The system's steady-state and dynamic operation are characterised. • The role of system charge pressure and working fluid concentration are assessed. • The experimentally calibrated model predicts steady-state COP to within ±20%. • The peak heat source temperature during start-up is predicted to within ±10 K. [ABSTRACT FROM AUTHOR]

Fold-and-thrust belts and accretionary prisms exhibit considerable variability in slip behaviors along active faults. While numerous studies have investigated fault mechanics and slip behaviors in carbonate-, shale-, and sandstone-hosted faults as well as clay-rich portions of shallow accretionary prisms, the deformation mechanisms and slip behaviors of deformed, thrust-top molasse-type conglomerates remain poorly understood. To fill this knowledge gap, we conducted structural and microstructural analyses on exhumed and deformed conglomerates in the footwall of an out-of-sequence thrust from the Central Apennines fold-and-thrust belt (Italy). Our findings aim to constrain conglomerate deformation mechanisms and infer possible slip behaviors. We observed flattened pebbles and an intense foliation comprising densely spaced, thrust-parallel, clay-rich stylolites that indicate slow deformation attributed to carbonate dissolution during aseismic creep. In contrast, quartz clasts with calcite micro veins and micrometer-thick slip increments in slickenfibers suggest fast brittle failure and fluid overpressure in competent pebbles, while the matrix continues to deform aseismically through pressure solution. The general structure is similar to block-in-matrix textures observed in tectonic mélanges from exhumed subduction zones and accretionary prisms. Our results provide new insights into the slip behaviors of shallow (<∼1 km) portions of fold-and-thrust belts, complementing existing understandings of deformation mechanisms and slip behaviors across different depth ranges in fold-and-thrust belts and accretionary prisms. [Display omitted] • Deformed conglomerates show a block in matrix texture similar to tectonic mélanges. • Microstructures reveal slow aseismic creep and fast brittle failure. • Aseismic pressure solution flattened and deformed carbonate and quartz pebbles. • Micro veins and slickenfibres suggest brittle failure due to fluid pressure release. [ABSTRACT FROM AUTHOR]

In this paper we extend recent results obtained for the Navier–Stokes equations to propose and analyze a new fully mixed virtual element method (mixed-VEM) for the stationary two-dimensional Boussinesq equations appearing in non-isothermal flow phenomena. The model consists of a Navier–Stokes type system, modeling the velocity and the pressure of the fluid, coupled to an advection-diffusion equation for the temperature. The variational formulation is based on the introduction of the additional unknowns given by a modified pseudostress tensor, which depends on the pressure, and the diffusive and convective terms of the fluid, and the pseudoheat vector, which involves the temperature, its gradient, and the velocity. As a consequence of the former, the pressure is eliminated from the system, but computed afterwards via a post-processing formula. In turn, for the Galerkin approximation we follow the approach employed in a previous work introducing for the first time an L p spaces-based mixed-VEM for the Navier–Stokes equations, and couple it with a similar mixed-VEM for the convection–diffusion equation modeling the temperature. The solvability analysis of the resulting coupled discrete scheme is carried out by using appropriate fixed-point arguments, along with the discrete versions of the Babuška–Brezzi theory and the Banach-Nečas-Babuška theorem, both in subspaces of Banach spaces. The first Strang lemma is applied to derive the a priori error estimates for the virtual element solution as well as for the fully computable approximation of the pseudostress tensor, the pseudoheat vector, and the post-processed pressure. Finally, several numerical results, illustrating the performance of the mixed-VEM scheme and confirming the rates of convergence predicted by the theory, are reported. [ABSTRACT FROM AUTHOR]

• A seismic back-front always exists during injection for natural and induced sequences. • It is infrequent after the injection shut-in, and related to large pressure drop. • The fluid-induced slip driving the swarm is totally aseismic near the injection point. • Minimum magnitude of the seismic events is increasing close to the injection point. • The back-front may be linked to the increase of the earthquake nucleation length. Seismic swarms represent clusters of seismicity without large mainshocks. While they occur naturally, they can also be induced by human activities, particularly during reservoir hydraulic stimulations. A striking feature of seismic swarms is the migration of their hypocenters. The seismic front, initially attributed to fluid diffusion, has more recently been understood as the result of the propagation of a fluid-induced aseismic slip. Close to the center of the swarm, a seismic back-front is commonly admitted after the injection end, but a low density of events is also observed during the injection period. In our investigation, based on a compilation of 22 swarms of both natural or anthropogenic origin, we aim to explore the existence and origin of a seismic back-front. Interestingly, we observe a post-injection back-front only in rare cases, where a rapid fluid pressure decrease is imposed at the injection point. Conversely, a back-front during the injection period is always observed in both types of swarms. Consequently, the back-front cannot be reliably used to infer the end of injection, as commonly done for natural swarms. Moreover, the occurrence of this back-front during injection is linked to an increase in the minimum magnitude of seismic events. We interpret the vanishing of the seismicity close to the injection point as a consequence of the increase in earthquake nucleation length with increasing fluid pressure. With a substantially enhanced capability for detecting small events, it may become feasible to use this back-front as a means of monitoring injection pressure, even in the context of natural swarms. [ABSTRACT FROM AUTHOR]

This paper investigated the post-buckling behaviors of a variable-arc-length (VAL) elastica pipe caused by internal transporting fluid motion, accounting for the effects of the self-weight and variation of internal fluid pressure. Both weak-form and strong-form formulations of the VAL elastica pipe were developed. The weak-form formulation was derived by the virtual work principle, and later solved using the nonlinear finite element method (FEM). The strong-form formulation was derived using equilibrium of the force and moment equations, the geometrical relationship of the differential pipe segment, and the energy conservation of the transported fluid. Because of the large displacement analysis, the variation in the internal pressure inside the pipe was considered, which was taken into account by energy conservation based on the Bernoulli principle. Then, the set of nonlinear governing first-order differential equations, corresponding to the two-point boundary value problem, was conveniently solved using the shooting optimization method (SOM). The numerical results obtained from the presented FEM and SOM analyses independently verified each other, with good agreement between these two methods. The parametric study considered the effects of gravity load (pipe and fluid self-weights) and internal fluid pressure on the post-buckling characteristics of the VAL pipe. The numerical results showed that without the pipe and internal fluid weights, the transporting fluid exerted an axial compressive force on the pipe, causing post-buckling phenomena. Beyond the critical state, the support rotation and the length of the VAL pipe increased as the internal fluid velocity decreased. Finally, by including the effect of self-weight, the mode exchange of the odd buckling modes (1st and 3rd modes) was found from the load-displacement path. • Post-buckling of VAL elastica pipe conveying fluid accounting for effects of self-weight and pressure variation is presented. • Strong form and weak form formulations of VAL pipe are derived using equilibrium equation and virtual work principle, respectively. • Numerical results for a VAL elastica pipe are solved using FEM and SOM analyses. • Effect of self-weight induces buckling mode transition phenomenon between odd buckling modes (1st and 3rd modes). [ABSTRACT FROM AUTHOR]

Currently, with the increase in the number of climate anomalies, the frequency and severity of landslides and slope failure events are gradually escalating. Therefore, it is imperative to develop a reliable approach that can assess the evolution of slope stability under the long-term climate effects. This study proposes a feasible framework for the approach. Firstly, a finite element (FE) numerical model that integrates thermal–hydraulic (TH) coupling analysis and land–atmosphere interaction process is established. Particularly, a new algorithm for dealing with the unilateral boundary condition of evaporation and infiltration has been proposed. Secondly, a method combining the numerical simulation with discretization-based upper-bound limit analysis approach is employed to evaluate the slope stability. Finally, the performance of the proposed scheme is tested by tracking the evolution of a cut slope stability under climate influence. Results of the case study suggest that significant variation in equivalent pore fluid pressure (EPFP) with suction is crucial for the stability of unsaturated soil slopes. EPFP is strongly dependent on seasonal climate change. Moreover, the stability analysis method adopted can effectively capture the transformation of slope failure modes. [ABSTRACT FROM AUTHOR]

Hydroshearing has been proposed as an effective technique for enhancing the permeability of fractured geothermal reservoirs. This approach involves complicated thermo-hydro-mechanical (THM) coupling, but the shear behaviour and its effect on flow and heat transfer are often simplified. In this study, Barton–Bandis (BB) joint behaviour is extended to include nonlinear rock joint deformation, shear dilation and post peak softening and healing behaviours. Two models of field-scale fractured geothermal reservoirs are considered. In addition, the widely used Mohr-Coulomb (MC) model is also incorporated into the THM coupled model for comparison. The results show that cold water injection-induced high-temperature rock contraction and fluid pressure increase, reducing the effective stress and promoting fracture shear deformation and irreversible slip. Moreover, shear dilation, shear softening, and nonlinear fracture opening notably alter reservoir permeability. The two models exhibit entirely different behaviours due to different pathway evolutions and consequent pressure build-up. The BB model displays a larger shear disturbance zone than the MC model, significantly enhancing the permeability and heat extraction within the fractured reservoirs. Accurate descriptions of the mechanical behaviour of rock fractures in hydroshearing models are crucial, suggesting the potential of these models to enhance fractured reservoirs and regulate fracturing for improved geothermal heat extraction. [ABSTRACT FROM AUTHOR]

Geological carbon dioxide storage is one of the most effective technologies to reduce greenhouse gas emissions to the atmosphere. The mineral dissolution is inevitable during the long-term storage process, while the chemical effect on fault slip behavior remains poorly understood. In this paper, we present a hydro-chemical–mechanical coupled fault reactivation study using the unified pipe-interface element method (UP-IEM). The impact of chemical dissolution on stress redistribution is considered. The accuracy of the numerical method to simulate reactive solute transport and fault frictional slip are confirmed by analytical solution and numerical verification. Two different fault tectonic scenarios, of which fault locating in the caprock and fault crosscutting the reservoir and caprock, are designed to investigate the fault slip behavior induced by mineral dissolution. The effect of dissolved CO 2 solute concentration, fault aperture, reservoir permeability and chemical reaction rate are discussed. Results show that fault locating in the caprock is easier to be activated. The chemical reaction has a more significant effect on fault slip behavior than fluid pressure during the long-term low-velocity CO 2 leakage. The increase of CO 2 solute concentration and reservoir reaction rate cause an obvious growth on fault slip displacement. The decrease of fault initial aperture results in the fault slip velocity slower and the slipping area smaller. The high-permeability reservoir keeps the fault more stable than low-permeability reservoir under the influence of mineral dissolution. • A HCM coupled fault reactivation model is developed using UP-IEM. • Reaction has larger effects than pressure on fault slip during low-velocity CO 2 leakage. • Fault locating in the low-permeable formation is easier to be activated. [ABSTRACT FROM AUTHOR]

• We provide a theoretical method to investigate the transient behavior of a rectangular plate partially in contact with fluid subjected to a dynamic external force. • Experiments were conducted using piezoelectric film sensors to measure the force history induced by a steel ball impact to quantitatively analyze the transient response. • The transient solution demonstrates an analytical approach that connects the physical significance of the dynamic behavior of the fluid-plate coupled system in time and frequency domains. • We provides a connection between the transient behaviors and vibration characteristics. • The results indicate that changes in water depth can influence the resonance frequency shifts and wet mode shape distortions. This study aimed to investigate the transient behavior of a rectangular plate partially in contact with fluid subjected to a dynamic external force. To this purpose, a theoretical model was developed to analyze vibration characteristics and transient wave propagation. Based on superposition method, the dry mode shapes and natural frequencies of the plate under vacuum could be obtained. The dry mode shapes were treated as the fundamental function to construct the wet mode that describes the vibration behavior of the fluid-plate coupled system. The velocity potential and fluid pressure within a finite tank due to the plate deflection were derived using an equation governing the incompressible fluid. Based on the relationship between dry mode shape and wet mode shape, the fluid-plate coupled system's wet mode shape and resonant frequency could be determined from the frequency response function. Applying the normal mode method, the transient displacement of plate and fluid pressure can be obtained by solving a system of non-homogeneous differential equations. The theoretical predictions were verified by finite element method (FEM) and experimental measurements. Experiments were conducted using piezoelectric film sensors (polyvinylidene fluoride, PVDF) to measure the force history induced by a steel ball impact to quantitatively analyze the transient response. The comparison results proved that the theoretical predictions and experiments were in good agreement, including the transient responses of the displacement and in-plane strain of a plate partially submerged in the fluid. The results indicate that changes in water depth can induce resonance frequency shifts and wet mode shape distortions, which also illustrate that the vibrational properties of wet modes affect transient behavior. The proposed transient solution demonstrates an analytical approach that connects the physical significance of the dynamic behavior of the fluid-plate coupled system in time and frequency domains; it provides a connection between the transient behaviors and vibration characteristics. [ABSTRACT FROM AUTHOR]

Stroh's sextic formalism represents the equilibrium equations of anisotropic elasticity in a particularly attractive form, that is most suitable for studying interface-dominated multilayered solids, composite materials and time-harmonic problems. Taking advantage of the fact that the Stroh formalism really amounts to the canonical form of the equations in the Hamiltonian sense, the case of Biot's reversible (i.e. no fluid dissipation) poroelasticity is here addressed, in the absence of a fluid pressure gradient. This framework is the same as thermoelasticity of perfect conductors. Two Hamiltonian formulations are developed: the first describes both the solid and the fluid phases and it exhibits, besides energy conservation, momentum conservation, as a result of pressure uniformity (perfectly drained conditions). The second is restricted to the solid skeleton and perfectly parallels anisotropic elasticity, where the Stroh matrices refer to the effective stress tensor. The case of weak fluid–solid coupling is also considered and it produces a perturbation from anisotropic elasticity with the same structure as incompressibility, although in an "opposing" manner. This comparison suggests that the incompressibility limit introduced by Biot should be revised. The energy conservation integral and the edge impedance matrix are also illustrated. • The Stroh-like form of the equations of reversible poroelasticity is derived. • Accounting for both solid and fluid, energy and momentum conservation hold. • Accounting for the solid alone, the structure of anisotropic elasticity is retrieved. • Biot's incompressible limit does not lend incompressible elasticity. • Instead, weak solid–fluid coupling provides a correction similar to incompressibility. [ABSTRACT FROM AUTHOR]

Articular cartilage, primarily composed of water and collagen, is vital for synovial joint function. Traditional hard biomaterials like ceramic or cobalt-chrome used in hemiarthroplasty often result in abnormal contact pressures and premature implant failure. This study investigates the tribological properties of polyelectrolyte functionalised PEEK (SPMK-g-PEEK) in contact with cartilage, proposing a solution to these issues by utilising tribological rehydration and effective aqueous lubrication. We demonstrate a new mode of polyelectrolyte enhanced tribological rehydration where SPMK-g-PEEK achieves low friction and promotes interstitial fluid recovery during sliding, independent of traditional hydrodynamic theories. This results in a rapid stabilisation of the coefficient of friction (CoF) to levels comparable to natural cartilage (CoF ∼ 0.01) and aids in approximately 8% cartilage strain recovery, indicating effective tribological rehydration even under cartilage degradation or altered osmotic conditions. Furthermore, we find that lubrication and rehydration against an SPMK-g-PEEK interface depend minimally on biphasic lubrication but significantly on the hydrophilic sulfonic acid groups of SPMK, which act as a fluid reservoir. Our findings suggest SPMK-g-PEEK as a promising biomaterial for cartilage interfacing implants that offer low friction and modulate cartilage interstitial fluid pressure. This study enhances our understanding of biotribological interactions and contributes to the development of joint replacement materials that support the natural function of cartilage. [ABSTRACT FROM AUTHOR]

A radial shaft seal (RSS) model is established to reveal mixed thermal lubrication (MTL) and wear performance at speeds ranging from 3000 r/min to 7000 r/min. The model takes into account the initial temperatures of the oil medium and the running time of the RSS to investigate the transition limit of lubrication. Then a thermal fluid-solid method was developed to simulate the lubrication performance of RSS, which shows lubrication transition boundaries through rough micro convex bodies for wear deformation. The RSS deforms wedge-shaped during the wear process and a localized fluid pressure is created on the convex bodies. Considering the wear deformation of the convex bodies due to the wedge effect, the micro performance of the RSS can fully describe the mechanism of the leakage rate. As the dynamic pressure decreases and the leakage rate increases with the temperature of the medium, the RSS lubrication gradually transitions from MTL to EHL. Thus, the initial medium temperature should be considered to maintain the RSS under the mixed lubrication regime with low friction. [ABSTRACT FROM AUTHOR]

Considering the fluid-structure impacting failure problems with large size, this paper presents an extended multi-resolution smoothed particle hydrodynamics (SPH)-peridynamics (PD) coupling model. The influence domain and the interpolation smoothing length are innovatively introduced to reconstruct governing equations for interactions between particles of diverse resolutions, ensuring system-wide momentum conservation. Then, an adaptive multi-level cell neighborhood search (AMC NS) algorithm is presented, designed to reduce the time of neighborhood search in multi-resolution simulations. Several 2D and 3D validation tests demonstrate the accuracy of the multi-resolution SPH-PD model in describing solid deformation and fluid impact pressure. The multi-resolution SPH-PD model significantly enhances computational efficiency and can depict the process of structural failure under conditions where a wide difference in scale between waves and structures. [ABSTRACT FROM AUTHOR]

Understanding how in-situ mineralization of CO 2 affects the porosity, permeability, and pore network of the host rock is critical to assessing the viability of basalt reservoirs as carbon dioxide repositories. Here, we present an x-ray translucent environmental cell which allows carbon mineralization, and other fluid–rock reactions to be studied in real time and on the grain scale under simulated geological reservoir conditions using microtomographic imaging. The cell operates autonomously from a CT instrument and is periodically quenched and relocated for scanning, enabling long duration operando experiments. Samples are reacted under controlled conditions of chemistry, temperature, and fluid pressure. Porosity and permeability changes are tracked through digital image analysis of successive CT scans. Samples are fully recoverable, allowing for a suite of post-mortem analyses. The cell design uses readily available materials, can sustain long-term operating temperatures of up to 200 °C, and is reproducible at low cost with a centre lathe and a mill using a conveniently equipped mechanical workshop. • Technical drawings for reaction cell presented. • Enables simulation of geological CO 2 storage environments. • Suited to investigation CO 2 storage by mineralization. • Enables x-ray imaging of entire mineralization reaction. • Allows for investigation of rock properties on micron scale. [ABSTRACT FROM AUTHOR]

A well-designed exhaust manifold has a positive effect on the efficiency of an engine and exhaust emissions. If the dimensions and geometric structure of the exhaust manifold are not designed in accordance with the pressure fluctuations of the fluid, this will have a negative effect on the velocity, temperature, density and pressure of the flow. In view of this and the high production costs of locomotive diesel engines, the pressure and velocity distributions in the exhaust manifold of a six-cylinder locomotive engine are investigated numerically in this study. Two different designs for the diesel engine are studied, taking into consideration the area in which the exhaust manifold will be mounted and the other engine parts. The pressure and velocity variations of the exhaust manifolds are compared via a computational fluid dynamics analysis, and analyses are performed using test data from a heavy-duty diesel engine at different power values (225, 450, 675, and 900 HP) and 1500 rpm, with the aim of finding the optimal design. Since the diameters at the cylinder outlets cannot be changed, the designs are created to fit within the existing area of the engine area The exhaust outlet is located in the middle of the manifold in the first model examined here, and is positioned close to the right-hand side of the manifold in the second model (the existing configuration). It is found that the flow becomes more efficient in the model in which the outlet is in the middle of the exhaust manifold. [ABSTRACT FROM AUTHOR]

• The pressurizing rate model considering the physical properties of CO 2 is proposed. • A novel breakdown pressure model considering fluid infiltration effect is proposed. • The low viscosity and pressurization rate of CO 2 decreases breakdown pressure. • Influence of the pore pressure distribution on breakdown pressure is analyzed. • The pressurization rate affects breakdown pressure at different injection rates. Precisely predicting the breakdown pressure of rock fractured by supercritical CO 2 (SC-CO 2) is one of the major challenges for optimize in-situ fracturing schemes. However, the influence of the infiltration effect caused by the unique properties of SC-CO 2 on the fracture mechanism remains unclear, which may lead to inaccurate prediction of breakdown pressure. In this work, a pressurization rate model considering the physical properties changes of SC-CO 2 is proposed to describe the relationship between the pressurization rate and the injection pressure of the fracturing fluid in a wellbore. Ultimately, combined with the pressurization rate model and the point stress criterion, a breakdown pressure model is established by considering the changes in the in-situ stress of wellbore surrounding rock, the fluid injection pressure inside the wellbore, and the pore pressure distribution. The results show that for permeable reservoirs, the breakdown pressure increases as the viscosity and injection rate of fracturing fluid increase, but it decreases with increasing rock permeability. The low viscosity and pressurization rate of SC-CO 2 effectively increase the stress generated by the infiltration effect, which is negatively correlated with the breakdown pressure. In addition, the unique pressurization rate of SC-CO 2 is the key factor for the abnormal breakdown pressure at different injection rates. [ABSTRACT FROM AUTHOR]

• Shattered garnet grains observed in a Patagonian high pressure metasediment. • 2D visco-elasto-plastic models used for assessing the mechanical conditions for fracturing. • Garnet in quartzite fractures under strain rates faster than for steady state creep rates. • Fractured garnet crystals in weak metasediments may record transient accelerated slip rates. A paradox exists between the great number of intermediate-depth earthquakes occurring along active subduction interfaces worldwide and the extreme scarcity of paleo-seismic events recorded in exhumed metasediments from ancient subducted slabs. Recrystallization associated with exhumation-related overprinting generally contributes to the nearly-complete erasing of markers of unstable slip events in metamorphic rocks. We herein focus on a sample from an ancient deep thrust from a Cretaceous High-Pressure paleo-accretionary complex in Chilean Patagonia. A representative, moderately foliated micaschist exhibits broken garnet crystals that host a dense network of healed micro-fractures. While garnet fragments appear thoroughly disaggregated along the main foliation, the rock matrix that completely recrystallized has lost the record of brittle deformation. We employ a 2D visco-elasto-plastic numerical modelling approach in order to investigate the mechanical conditions that enable the fracturing of isolated garnet grains in a relatively weak matrix. The rupture of these stiff grains is achieved in our models at strain rates faster than 10−10 /s to 10−12 /s for elevated pore fluid pressures (80 to 99 % of the lithostatic value, respectively). Since high pore fluid pressures prevail in deep subduction interface settings, it is suggested that the rupture of these garnet crystals occurred through cataclastic deformation via (transient) slip rate acceleration, perhaps as a consequence of localized slip associated with slow to conventional earthquakes. Upon slip rate deceleration, viscous disaggregation of the broken garnet clasts occurred along with the erasing of the matrix cataclastic fabric. [Display omitted] [ABSTRACT FROM AUTHOR]

Fractures in organic-rich shale affect the evolution of permeability and control shale gas preservation. We characterize fracture attributes in the Qiyue-Huaying Fold-Thrust belt in the southeastern Sichuan Basin, revealing the distribution, origin and factors controlling fracture localization through investigation of cores, image logs, and thin section petrography. We found that the deformation intensity, organic matter content and lithology are the major factors for controlling fracture occurrence and location in the Wufeng-Longmaxi deep shale. The major fracture pattern in the Fuling Block is characterized by abundant inclined shear fractures, bed-parallel shear fractures, and bed-normal extension fractures, while bed-parallel veins prevail in the Luzhou Block. In general, fracture density and size in the Fuling Block are larger than those in the Luzhou Block. The competent layers (siliceous shale with high TOC) have the highest fracture density, and noticeably, organic matter content controls bed-parallel vein localization. Based on the distribution of fractures in two blocks, we suggest that the dominant origin of fractures in organic-rich shale gradually changes from tectonic events to fluid pressure changes due to organic maturation (organic events), from the Fuling Block to the Luzhou Block. • Attribute and distribution of fractures are presented in organic-rich shale. • The first-order link between the organic matter content and distribution of bed-parallel veins. • Fracture pattern is sensitive to organic events and tectonic events. [ABSTRACT FROM AUTHOR]

Episodic Tremor and Slip (ETS) events showcase dynamic interactions of oscillatory slow slips and tremors deep within subduction zones and offer a window into Earth's internal dynamics. However, the exact mechanisms driving these events remain unresolved. This study proposes a novel approach that goes beyond traditional explanations focused on fluid pressure from mineral dehydration. Existing models often neglect the intricate interplay between fluid and rock pressures across various depths and potential fluid sources. This calls for a more comprehensive understanding of how fluid release from reactions interacts with rock deformation. The present formulation captures the interplay between fluid and solid pressures providing a more rigorous picture of ETS events. It employs a minimalistic and efficient approach based on integrating dehydration reactions. The model thereby develops a generic framework for mineral dehydration, offering an enhanced perspective of the underlying processes without the need to trace down to specific minerals. It allows a refined fit to GPS data by including high-frequency components from linear and nonlinear stability analyses, giving rise to improved correlation coefficients. Through the inclusion of the dynamic interplay between fluid and rock pressure diffusion within subduction zones, we propose a unified model of ETS events. [Display omitted] • Mineral breakdown reactions provide a basis for modeling Episodic Tremor and Slip events. • Inversion of GPS time series allow prediction of fluid production rates in the subduction zone. • Similar mineral reaction cross-diffusion parameters are derived for Cascadia and Hikurangi. • Cross-reactions of fluid pressure on matrix pressure constitute the main difference. • The approach opens a path for quantifying and tracking fluid release reaction rates. [ABSTRACT FROM AUTHOR]

In this paper, the quasi-static and dynamic behavior of partially fluid-saturated concrete under two-dimensional (2D) uniaxial tension at the mesoscale is investigated numerically. It was calculated what effect the free pore fluid content (gas and water) had on the fracture process and strength of concrete in a tension regime. An improved pore-scale hydro-mechanical model based on DEM/CFD was used to simulate the behavior of fully and partially fluid-saturated concrete in quasi-static and dynamic conditions. The foundation of the fluid flow idea was a network of channels in a continuous area between discrete elements. In very porous, partially saturated concrete, a two-phase laminar fluid flow was proposed. To track the liquid/gas content, the position and volumes of the pores and cracks were considered. Numerical simulations of bonded granular specimens of a simplified spherical mesostructure that resembled concrete were carried out under dry and wet circumstances for two different strain rates. Investigations were conducted on the effects of fluid pore pressures, fluid saturations, and fluid viscosities on the strength and fracture process of concrete. The quasi-static tensile strength dropped nonlinearly with increasing fluid saturation and fluid viscosity during fluid migration through pores and cracks which contributed to a promoted fracture process. However, during rapid dynamic tensile deformation, a fracture process attenuated due to a fluid migration constraint from insufficient time to exit the pores. It caused the dynamic tensile strength to rise nonlinearly as fluid saturation and fluid viscosity increased. [ABSTRACT FROM AUTHOR]