Increase In Hydrostatic Pressure Research Articles

Interaction of an electron and a uniformly charged spherical donor impurity

In this study, we propose an interaction potential between an electron and a uniformly charged spherical donor impurity in a quantum dot and numerically solve the Schrödinger equation using the finite difference method. We investigate the effects of the potential depth, donor radius, temperature, and hydrostatic pressure on the electronic and optical properties of an electron-donor impurity in a quantum dot, including absorption coefficients and the total change in the relative refractive index during the transition of an electron from the ground (1s) to excited (2p) states in the conduction band. Our findings indicate that an increase in donor radius or temperature leads to a red shift in the optical response, holding the parameters constant. Conversely, an increase in potential depth or hydrostatic pressure induces a blue shift in the optical response under the constant parameters.

Time-Dependent Fuzzy Reliability Analysis of Concrete Slab during the Initial Water Storage Period of CFRD: A Case Study

The concrete-faced rockfill dam (CFRD) has been widely constructed worldwide, and the reliability of the concrete panels, the most important containment structure, is critical to the safety of the CFRDs and downstream communities. Several practical projects show that concrete slab cracking usually occurs during the water storage period, which can be attributed to the rapid increase of hydrostatic pressure and uneven settlement of the dam body. In this paper, a time-dependent reliability analysis method considering the fuzziness of the failure criterion is presented to assess the slab cracking risk of the Houziyan CFRD during the water storage period. Based on the observed deformation, the material parameters are calibrated to ensure the fidelity of the numerical simulation. Based on the Drucker–Prager yield criterion and tensile strength criterion, the response surface method is utilized to construct the performance functions at different moments, and then the time-dependent reliability analysis considering the fuzzy failure criteria is implemented for the concrete slab. The case study of the Houziyan CFRD shows that, during the initial period of water storage, the reliability index of the concrete slab decreases with the rise of the water level. With a stable water level, the probability of cracking of the concrete slab slowly decreases as the deformation of the dam body and slab tend to be coordinated. Especially, considering the fuzziness of the failure criteria, the reliability index decreased by about 2%, indicating that the proposed evaluation method is biased toward safety. The method proposed in this paper can reflect the evolution law of concrete slab reliability with the operating environment and provides a new approach to evaluate the performance of the concrete slab during the water storage period.

Spectral and optical properties of a [formula omitted] molecular complex confined in InAs/GaAs Quantum Camels: A spatial finite element method treatment

The evolution of eigenstates and related optical absorption (sum of linear and nonlinear contributions) of a singly ionized double donor (D2+) confined in InAs/GaAs (quantum-well-dot nanostructure) quantum camels were theoretically investigated. Within the effective mass and the compact density matrix approximations, the energy levels and optical absorption were characterized as a function of a hydrostatic pressure field applied, the sample temperature, and the wetting layer thickness via a spatial finite element method analysis. Results show that an increase of hydrostatic pressure (sample temperature) between 0 to 30 kbar (4 to 300 K) leads to a stabilization (destabilization) of the energy levels and a decrease (increase) of the absorption peak value with a red-shift (blue-shift). On the other hand, an increase in the wetting layer thickness leads to a reduction in the energy levels, and a monotonous evolution from quantum-dot states to wetting-layer states, especially in the excited ones, is seen. In addition, an increase in the absorption peak value is reported, which can be intended as an electron mobility enhancement. The donor-electron interactions reduce the wavefunction’s spatially-extended feature, enhancing the absorption peak in the analyzed |1〉→|6〉 transition. In the |1〉→|2〉 optical transition, the resonant peak can be tuned within the band ≈25–48 meV, slightly beyond the Terahertz frequency range.

NEGATIVE PRESSURE PULMONARY EDEMA AFTER GENERAL ANESTHESIA

Abstract
 Negative pressure pulmonary oedema is a type of non-cardiogenic pulmonary oedema caused by strong inspiratory effort to overcome obstruction in the upper airways. The main mechanisms responsible for the pathophysiology are the increase in pulmonary capillary hydrostatic pressure and the increase in capillary membrane permeability that develops after the negative intrathoracic pressure increases with inspiratory effort. Although all causes that may lead to upper airway obstruction may play a role in the etiology, the most common factor is laryngospasm that develops during awakening from anaesthesia. Young male smokers under general anaesthesia are more at risk. Onset may vary from a few minutes to several hours after extubation or relief of laryngospasm. It leads to an acute respiratory failure that is potentially life-threatening and usually requires follow-up and treatment in the intensive care unit. The first step in treatment is to relieve airway obstruction and provide oxygen support. Positive pressure ventilation and use of diuretics are beneficial and usually tend to improve within 24-48 hours. The mortality rate is reported to be around 5% in case analysis reports of recent years. Since it is observed more frequently in anaesthetised patients, early diagnosis and treatment in the postoperative period is important. The aim of this review is to present a current perspective on negative pressure pulmonary oedema in the light of the literature.

Diagnostic Accuracy of Lung Ultrasonography Compared to Chest Radiography, BNP, and Physical Examination in Patients with Dyspnea Suggestive of Pulmonary Edema: A Systematic Review and Meta-Analysis

Background:: Pulmonary edema (PE) is the result of an abrupt increase in hydrostatic pressure in the pulmonary capillaries that leads to leakage of fluid through microvascular endothelial cells. This leads to a disruption of gas exchange in the lungs. Aims:: This meta-analysis aimed to determine the diagnostic accuracy of lung ultrasonography (LUS) in pulmonary edema. Methods:: A systematic search was conducted using a strategy based on these search terms (Lung ultrasonography, pulmonary edema, diagnostic accuracy); we searched PubMed, Google Scholar, and the Cochrane Library. Out of 1029, 14 prospective cross-sectional and observational studies with 2239 patients who reported the sensitivity and specificity of lung ultrasonography in diagnosing pulmonary edema were selected. For inclusion and data extraction, an independent review of citations was carried out. The data obtained were analyzed using SPSS, RevMan 5.3, and Stata 14.0 software. A quality assessment was conducted using the QUADAS-2 tool. The reference gold standard was the final clinical diagnosis according to chest radiography, B-type natriuretic peptide, and/or physical examination in dyspneic patients. Results:: The overall sensitivity and specificity of lung ultrasonography in the diagnosis of pulmonary edema were 0.86 (95% CI, 0.81-0.90) and 0.91 (95% CI, 0.90-0.93), respectively, with a Younden index of 77.8%. The area under the receiver operating characteristic (ROC) curve was 0.889. Conclusion:: The overall diagnostic odds ratio was 68.86. The results of this meta-analysis suggest that lung ultrasonography is an effective non-invasive technique in the diagnosis of acute pulmonary edema with rapid bedside examination and immediate interpretation

A novel pressure compensated structure of lithium-ion battery pack for deep-sea autonomous underwater vehicle

The battery pack of deep-sea autonomous underwater vehicle (AUV) is placed in a heavy shell to protect the batteries from external pressure and moisture in a conventional manner. In recent years, the pressure compensated structure with thin film based on oil immersion has been gradually applied to the deep-sea AUV battery pack to achieve lightweight design. In this paper, the ratio of the structural parts of the pressure tolerated and pressure-compensated structures of the cabin to the total weight of the battery pack is systematically analyzed respectively in the depth range of 300– 6000 m, and a new pressure compensated structure with piston based on oil immersion is proposed. The mechanical properties and thermal characteristics of this structure are simulated and analyzed. Finally, the functionality of the compensated structure is verified by the established pressure test platform. The results show that the weight of conventional pressure tolerated structure increases nonlinearly with the increase of hydrostatic pressure to resist external hydrostatic pressure. The proposed pressure compensated structure with piston not only saves at least 18.3 % of the structural component weight at a hydrostatic pressure of 60 MPa, but also reduces the surface temperature of the battery pack due to the presence of dimethyl silicone oil as a pressure transfer medium.

Damage Characteristics and Dynamic Response of RC Shells Subjected to Underwater Shock Wave

Underwater bottom-sitting shell structures face threats from underwater explosion shock waves. To investigate the damage characteristics and dynamic response of bottom-sitting shell structures under underwater explosion shock waves, three-dimensional numerical models of semi-spherical and semi-cylindrical bottom-sitting reinforced concrete (RC) shells under underwater shock waves were established based on the Arbitrary Lagrangian–Eulerian (ALE) algorithm using LS-DYNA software. The influences of the shock wave transmission medium, explosive equivalent, explosive distance, hydrostatic pressure, and reinforcement on the damage characteristics and dynamic response of semi-spherical and semi-cylindrical bottom-sitting RC shell structures were studied. The results indicated that the damage and center vertical deformation of RC shells under underwater shock waves are significantly greater than those under air shock waves. With an increase in explosive equivalent or decrease in explosive distance, the damage and center vertical deformation of RC shells are increased. The damage to the inner surface of RC shells is more severe than the outer surface. The damage and center vertical deformation of RC shells can be reduced by bottom reinforcement and an increase in the diameter of the steel bar. The ‘hoop effect’ caused by hydrostatic pressure restrains the horizontal convex deformation and slightly decreases the macroscopic damage and vertical center deformation of the semi-spherical RC shell with an increase in hydrostatic pressure within the range of 0–2.0092 MPa. The hydrostatic pressure restrains the horizontal convex deformation of the semi-cylindrical RC shell. However, inward concave deformation of the shell center is increased by hydrostatic pressure, inducing an increase in the damage to and center vertical deformation of the semi-cylindrical RC shell. These findings may offer a reference for the construction and design of protective measures for underwater bottom-sitting shell structures.

Effect of hydrostatic pressure on opto-electronic, elastic and thermoelectric properties of the double perovskites Rb<sub>2</sub>SeX<sub>6</sub>(X=Cl,Br): a DFT study

Double perovskites find applications across a diverse range of situations and varying pressure conditions. In this work, Quantum ESPRESSO code with a plane wave basis set was used to study the opto-electronic, elastic, and thermoelectric properties of Rb2SeX6 (X=Cl, Br) double perovskites under hydrostatic pressure (0 - 8 GPa). Perdew-Burke-Ernzerhof for Solids (PBESol) with generalized gradient approximation (GGA) was used as exchange-correlation functional. The band gap values of the materials decrease under hydrostatic pressure. Rb2SeCl6 has a band gap value of 2.44 eV at 0 GPa, 2.21 eV at 2 GPa. Above 2 GPa, the material has a metallic nature. Rb2SeBr6 has a band gap value of 1.56 eV at 0 GPa, but has a metallic nature under hydrostatic pressure (2 GPa to 8 GPa). The optical properties results indicate that the materials exhibit maximum absorption, high reflectivity, low optical loss in the visible and ultraviolet regions, good optical conductivity, and a refractive index suitable for use in opto-electronic applications. The materials are confirmed to be mechanically stable under all the hydrostatic pressure values studied. Electrical conductivity, thermal conductivity, and Seebeck coefficient (S ) values of the studied materials increase with an increase in hydrostatic pressure and temperature. The maximum value of S for Rb2SeBr6 is 0.248 x 103 (m V/k), while for Rb2SeCl6, maximum S = 0.175 x 103 (m V/k). The positive values of S suggest that the predominant charge carriers of Rb2SeCl6/Br6 are holes. Also, Rb2SeBr6 has a figure of merit (ZT) value of 3.44, while for Rb2SeCl6, ZT = 1.07. Since the values of ZT are greater than unity, the two double perovskite materials have good ZT values for thermoelectric device engineering. The results also suggest that Rb2SeBr6 is a better thermoelectric material than Rb2SeCl6.

Experimental investigation on mechanical response of soil reinforced by carbon nanotubes and silica dioxide nanoparticles

In the present study, three-axis dynamic tests were performed on different samples of soil, and the effect of montmorillonite based carbon nanotubes (CNT) and amorphous silica dioxide nanoparticles presence, density, hydrostatic pressure and moisture percentage on the elastic modulus and equivalent damping ratio of soil was investigated. Considering that in the present research, experimental studies and tests were carried out on three samples of sandy soil reinforced with 2 % volume fraction CNT, sandy soil reinforced with 8 % nanosilica and sandy soil reinforced with 0.5 % CNT and 4 % nanosilica. Also, the optimum moisture percentage has been determined for these types of soils. In general, with the increase of hydrostatic pressure and compaction of sand, the elastic modulus increases, and the amount of increase is different according to the type of nanoparticles. For 1 % applied strain and soil sand, with the increase of hydrostatic pressure from 100 kPa to 300 kPa, the elastic modulus of sand with 2 % CNT and 8 % nanosilica increases by 36 % and 214 %, respectively. This shows the favorable effect of silica nanoparticles on increasing the Young's modulus of sand by increasing the amount of hydrostatic pressure. The effect of CNT on improving the elastic modulus of sand in dry state is much higher than the effect of nanosilica. At 1 % strain and 4 % compaction, adding 2 % CNT to sand increases the elastic modulus of sand about 4 times compared to sand reinforced with 8 % nanosilica.

Investigation of nonlinear optical rectification within multilayer wurtzite InGaN/GaN cylindrical quantum dots under the impact of temperature and pressure

We have looked numerically at variations of the nonlinear optical rectification (NOR) for an impurity donor localized in a wurtzite Inx0Ga1−x0N/GaN multilayer cylindrical quantum dots (MLCQDs), which is under the effect of hydrostatic pressure and temperature. Using the effective mass approximation, the compact density matrix formalism, we have solved the Schrödinger equation by the finite element method (FEniCS Project) . Firstly, we consider the impact of altering the polarization direction of the incident electromagnetic radiation. Specifically, we explore two distinct scenarios: axial, along the growth axis of the structure, and circular, across the cross-section of the cylinder. From our investigation, we found that the nonlinear optical rectification is determined by two main parameters: the transition energy, which is mainly related to quantum confinement, and the geometrical factor that depends on the distribution of the electron wave functions. The NOR experiences a blueshift with an increase in hydrostatic pressure or indium composition, and a redshift with an increase in temperature or quantum dot radius, where the impurity is located in the center of the upper QD. Furthermore, the results show that the amplitude and resonance peak position of NOR are significantly influenced by varying the impurity’s position and the barrier width.

Synergetic support of cartilage homeostasis via coupled thermal-pressure stimuli: a transcriptomic study in human cartilage explants

During daily activities, cartilage encounters complex biophysical cues upon loading. Foremost among these is the coupled stimulation of hydrostatic pressure (HP) and loading-induced temperature increase (T), which encompasses both mechanical and thermal aspects of biophysical stimulations in cartilage. While prior research on this subject has been initiated in our laboratory, the detailed mechanisms of combined HP-T effects on chondrocytes in their natural environment remain largely unexplored. Using a custom bioreactor, we applied both isolated and combined HP-T stimuli to cartilage explants obtained from a non-inflammatory adolescent knee joint. Tissue and cellular responses were evaluated through histochemical staining and transcriptomic analyses, employing bulk RNA-sequencing complemented with signaling enrichment analyses. Our findings reveal that the thermal component of the coupled HP-T stimulation predominantly regulates the chondrocytes’ transcriptional profile during the stimulation period. When coupled with HP stimulation, a peak in chondroinduction was observed. This coupling process notably boosted chondroprotection in a synergistic manner, as demonstrated by the corresponding enhanced negative regulation of apoptotic processes and increased levels of Heat Shock Protein 70 (HSPA). Our study suggests that the upregulation in protein translation and processing, triggered by thermal stimulation, may serve as an adaptive mechanism in chondrocytes to mechanical simulations, thereby contributing to the observed synergy during the coupling of these two biophysical stimuli. The results highlight the potential of integrating thermal stimulation, a natural accompanying process during cartilage deformation, in tissue engineering, cell therapy or physiotherapy.

Fluid-structure interaction of spherical pressure hull implosion in deep-sea pressure: Experimental and numerical investigation

Implosion may occur when a hollow pressure structure with geometric imperfections works in deep-sea environments. Therefore, the implosion phenomenon and failure mechanisms of a titanium alloy spherical pressure hull are investigated by experiments and developed numerical methods in ultra-high-pressure water conditions. Firstly, the experiments were conducted using a full-ocean-depth sea environment simulator. Then the validity of the numerical analysis were demonstrated by comparing the shock wave of fluid and destroyed fragments of structure. Finally, the characteristics of underwater implosion were examined under different hydrostatic pressures, including the propagation of shock waves, high-speed motion of the compressible flow, nonlinear deformation of the spherical pressure hull, and energy balance and evolution. The results showed that the vertical impact effect occurs during the underwater implosion of a metallic sphere. Moreover, the shock wave emerges earlier and the cracks break into smaller fragments with the increase of hydrostatic pressure. Besides, the smaller volume of the air cavity is compressed and the larger amplitude of potential energy is dropped when the hydrostatic pressure is larger. Meanwhile, the internal energy of air and structure increases, while the internal and kinetic energy of air oscillates slightly due to the pulsation characteristics of the air cavity.

Unraveling cartilage degeneration through synergistic effects of hydrostatic pressure and biomimetic temperature increase

Cartilage degeneration, typically viewed as an irreversible, vicious cycle, sees a significant reduction in two essential biophysical cues: the well-established hydrostatic pressure (HP) and the recently discovered transient temperature increase. Our study aimed to evaluate the combined influence of these cues on maintaining cartilage homeostasis. To achieve this, we developed a customized bioreactor, designed to mimic the specific hydrostatic pressure and transient thermal increase experienced during human knee physiological activities. This system enabled us to investigate the response of human 3D-cultured chondrocytes and human cartilage explants to either isolated or combined hydrostatic pressure and thermal stimuli. Our study found that chondroinduction (SOX9, aggrecan, and sulfated glycosaminoglycan) and chondroprotection (HSP70) reached maximum expression levels when hydrostatic pressure and transient thermal increase acted in tandem, underscoring the critical role of these combined cues in preserving cartilage homeostasis. These findings led us to propose a refined model of the vicious cycle of cartilage degeneration.

Preparation of Cold Sprayed Titanium TA2 Coating by Irregular Powder and Evaluation of Its Corrosion Resistance

Titanium coating on a steel substrate by surface technology can improve the corrosion resistance of steel. In this paper, the titanium TA2 coating was deposited on X80 steel by cold spraying equipment with a low-cost irregular powder. The effects of the carrier gas temperature on the microstructure, microhardness, wear resistance, adhesion and corrosion resistance of titanium coatings, especially in a deep sea environment, were studied by methods of porosity analysis, thermal field emission scanning analysis, energy spectrum analysis, Vickers hardness tests, bonding strength tests, friction and wear tests and electrochemical tests. The results showed that as the carrier gas temperature increased from 300 °C to 900 °C, the porosity of the coating decreased to 0.93%, and the hardness and bonding strength of the coating increased to 247 HV0.5 and 46.7 MPa, respectively. With the increase in hydrostatic pressure from 0.1 MPa to 40 MPa, the dimensional blunt current density of the titanium coating with 0.93% porosity was still in the order of 10−7 A·cm−2 with the cast titanium TA2.

Effects of High Hydrostatic Pressure on the Structural, Electronic, and Elastic Properties, and Li-Ion Diffusion Barrier of Lithium Lanthanum Titanate Electrolytes: A DFT Study

Lithium lanthanum titanate perovskites (LLTO) are excellent solid electrolytes because of their good ionic conductivity and elasticity. In this work, the effects of high hydrostatic pressure and the impact of the position of Li impurities on the structural, electronic, elastic, and Li-ion diffusion properties of LaTiO3 perovskite (LTO) and its LLTO substitutional solid solutions, were studied. Density-Functional Theory (DFT) and Hubbard-corrected Local Density Approximation (LDA+U) were used. Due to hydrostatic pressure, the octahedral distortion of LTO, LLTO-layered (L), and -rock-salt (RS) electrolytes decreases, while it increases for the LLTO-columnar (C). On the other hand, the energy band gap () of LTO and LLTO-C decrease as hydrostatic pressure increases. For the LLTO-L, increases with pressure. For the LLTO-RS, decreases from zero to 20 GPa and increases from 20 to 30 GPa. Pugh’s criterion indicates that all systems are ductile regardless of applied pressure. Poisson’s ratio shows that bonds in the LTO are metallic, and LLTO-C is ionic-covalent. Likewise, LLTO-L and -RS electrolytes have a transition from ionic-covalent to metallic behavior, as pressure increases. Li-ion diffusion barriers of LLTO electrolytes increase with increasing hydrostatic pressure, indicating a decrease in Li ionic conductivity.

The role of radiation and halo mergers in Pop III star formation

ABSTRACT We present a study of the co-evolution of a population of primordial star-forming minihaloes at Cosmic Dawn. In this study, we highlight the influence of individual Population III stars on the ability of nearby minihaloes to form sufficient molecular hydrogen to undergo star formation. In the absence of radiation, we find the minimum halo mass required to bring about collapse to be ∼105 M⊙, this increases to ∼106 M⊙ after two stars have formed. We find an inverse relationship between halo mass and the time required for it to recover its molecular gas after being disrupted by radiation from a nearby star. We also take advantage of the extremely high resolution to investigate the effects of major and minor mergers on the gas content of star-forming minihaloes. Contrary to previous claims of fallback of supernova ejecta, we find minihaloes evacuated after hosting Pop III stars primarily recover gas through mergers with undisturbed haloes. We identify an intriguing type of major merger between recently evacuated haloes and gas-rich ones, finding that these ‘mixed’ mergers accelerate star formation instead of suppressing it like their low-redshift counterparts. We attribute this to the gas-poor nature of one of the merging haloes resulting in no significant rise in temperature or turbulence and instead inducing a rapid increase in central density and hydrostatic pressure. This constitutes a novel formation pathway for Pop III stars and establishes major mergers as potentially the primary source of gas, thus redefining the role of major mergers at this epoch.

Structural stiffness and equivalent viscous damping in a supercritical carbon dioxide lubricated hybrid journal bearing under hydrostatic status

PurposeThe purpose of this paper is to propose a type of hybrid bearing lubricated with supercritical carbon dioxide (S-CO2) and to investigate the stiffness and damping characteristics of the bearing under hydrostatic status.Design/methodology/approachEstablished a test rig for radial bearings lubricated with S-CO2 and used it to measure the dynamic coefficients by recording the relative and absolute displacements of bearing. Test bearing is mounted on a nonrotating, stiff shaft. Using static loading experiments to obtain structural stiffness. The dynamic coefficient regularities of the test bearing under hydrostatic status were revealed through dynamic loading experiments.FindingsExperiment results indicate that test bearing displayed increased stiffness when subjected to high excitation frequencies and low excitation forces, as well as elevated damping when exposed to low excitation frequencies and low excitation forces. Additionally, an increase in either environmental pressure or hydrostatic recess pressure can elevate the dynamic coefficient. The effect of temperature on the dynamic coefficient is more pronounced around the critical temperature of S-CO2.Originality/valueDesigned a type of hybrid bearing for use in the Brayton cycle that is lubricated with S-CO2 and uses hydrostatic lubrication during start-stop and hydrodynamic lubrication during high-speed operation. The hybrid bearing reduces the wear and friction power consumption of gas bearing. However, few experimental analyses have been conducted by researchers in this field.

The effect of hydrostatic pressure on grain refinement and deformation behaviors of Mg–Gd–Y–Zn–Zr alloy under complex shear stress

The effects of hydrostatic pressure on grain refinement and deformation behaviors of Mg–13Gd–4Y–2Zn–0.5Zr alloy were investigated. With the increase of hydrostatic pressure, the equivalent stress and forming load increase, and stress triaxiality also increases. The hydrostatic pressure has little effect on dynamic recrystallization (DRX) fraction and grain size, and the DRX fraction difference is not greater than 10%. This is because DRX critical strain and grain nucleation are almost unaffected by hydrostatic pressure. The slight increase in DRX fraction under higher hydrostatic pressure is attributed to the enhanced <a> dislocation activity near the lamellar long-period stacking ordered (LPSO) phase and significant local temperature elevation in the deformation zone. The high hydrostatic pressure is mainly borne by the LPSO phase. The bending deformation energy of the lamellar LPSO phase increases with the increase of hydrostatic pressure. The area fraction of samples is decreased from 18.5% of one direction compression & simple shear (1-CS) sample to 13.6% of three directions compression & simple shear (3-CS) sample. The solute diffusion and deconstruction of the bulk LPSO phase occur at higher hydrostatic pressure. The hydrostatic pressure has little effect on the basal texture strength of α-Mg phase under strong shear stress. The activation of <c+a> dislocation, as the primary source of non-basal slip, shows the same distribution characteristics.

Simultaneous Hydrostatic and Compressive Loading System for Mimicking the Mechanical Environment of Living Cartilage Tissue.

In vivo, articular cartilage tissue is surrounded by a cartilage membrane, and hydrostatic pressure (HP) and compressive strain increase simultaneously with the compressive stress. However, it has been impossible to investigate the effects of simultaneous loading in vitro. In this study, a bioreactor capable of applying compressive stress under HP was developed to reproduce ex vivo the same physical loading environment found in cartilage. First, a HP stimulation unit was constructed to apply a cyclic HP pressure-resistant chamber by controlling a pump and valve. A compression-loading mechanism that can apply compressive stress using an electromagnetic force was implemented in the chamber. The synchronization between the compression and HP units was evaluated, and the stimulation parameters were quantitatively evaluated. Physiological HP and compressive strain were applied to the chondrocytes encapsulated in alginate and gelatin gels after applying high HP at 25 MPa, which induced damage to the chondrocytes. It was found that compressive stimulation increased the expression of genes related to osteoarthritis. Furthermore, the simultaneous application of compressive strain and HP, which is similar to the physiological environment in cartilage, had an inhibitory effect on the expression of genes related to osteoarthritis. HP alone also suppressed the expression of osteoarthritis-related genes. Therefore, the simultaneous hydrostatic and compressive stress-loading device developed to simulate the mechanical environment in vivo may be an important tool for elucidating the mechanisms of disease onset and homeostasis in cartilage.

Experimental study on rock breaking by single chisel pick under deep-sea hydrostatic pressure

Mineral cutting and breaking is the first step in deep-sea mining. To investigate the effects of hydrostatic pressure on the rock cutting process, this study analyzed cutting force, specific energy (SE), and debris distribution parameters (coarseness index CI, debris size parameter de, debris size uniformity n, fractal dimension D) under hydrostatic pressures of 0–12 MPa using a self-designed deep-sea rock cutting test bench. The relationships between SE and debris distribution parameters were further analyzed. The experimental results showed that cutting force and SE increased significantly with increasing hydrostatic pressure, the maximum cutting force and SE were increased to 7 and 25 times the corresponding values under atmospheric conditions, respectively. The increase of hydrostatic pressure caused the rock debris size to gradually decrease, but the debris uniformity first decreased and then increased. Higher CI and de, indicated smaller SE. Meanwhile lower n and D, demonstrated smaller SE. CI was identified as a reasonable debris distribution parameter that could be utilized to analyze rock breaking efficiency. This research provides insights into the rock breaking mechanism and offers experimental data and guidance for the design and simulation for deep-sea mining equipment.