Increase In Hydrostatic Pressure Research Articles

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.

Torsemide in Edema Associated with Hepatic Impairment.

Hepatic edema is caused by decreased hepatic protein synthesis, a consequence of decompensated liver cirrhosis. Fluid accumulation occurs when there is an increase in hydrostatic pressure in the hepatic sinusoids and splanchnic capillaries, as well as low albumin. The first-line treatment for cirrhosis-related ascites is an aldosterone antagonist (spironolactone); however, in severe and recurring ascites, a combination of aldosterone antagonists and loop diuretics (torsemide, furosemide, and bumetanide) is preferable. Torsemide outperformed furosemide in terms of natriuretic and diuretic effects at an equivalent dose. Pharmacological features of torsemide, such as lesser hypokalemia effect, longer duration of action, higher bioavailability, and extended half-life, make it a better alternative than furosemide. In clinical studies, it is considered a safer and more acceptable choice with fewer complications.

Muzzle bubble dynamics characterization of underwater launching

To comprehensively understand the dynamic behavior of muzzle bubbles during underwater launching, an emptying process aligned with the muzzle flow characteristics is established and an evaporative condensation mechanism is modeled according to the high temperature and pressure properties of the propellant gas. Utilizing the spherical bubble theory, which comprises the inflation process and evaporative condensation effects, the dynamics of muzzle bubbles and their corresponding pressure waves are investigated. The numerical simulation results well agree with the experimental observations in terms of bubble radius and near-field pressure waves. Furthermore, the influence of two key factors on the bubble dynamics is examined: underwater launching depth and initial muzzle pressures. The results illustrate that the inflation process needs to be accurately described for precise pressure wave predictions. Using the evaporation condensation model, the bubble radius and frequency can be accurately characterized. Moreover, the launching depth influences the free expansion radius and oscillation frequency mostly due to the increase in hydrostatic pressure, which decreases by 33% and increases by 150% in the 1–20 m range, respectively. The initial muzzle pressure affects the initial expansion velocity and initial shock wave mainly due to the increase in the mass flow rate, which increase by 56% and 82% in the 35–65 MPa range, respectively.

Unraveling lead-free Fr-based perovskites FrQCl3 (Q = Ca, Sr) and their pressure induced physical properties: DFT analysis for advancing optoelectronic performance

A comprehensive study of structural, electronic, elastic, and optical properties of the cubic FrQCl3 (Q = Ca, Sr) perovskite under pressure 0 − 105 GPa has been considered. Interestingly, FrCaCl3 experiences a shift from an indirect to a direct bandgap material at 12 GPa, while FrSrCl3 undergoes the same shift at 10 GPa, rendering these materials more advantageous for application in optoelectronic devices. As pressure rises, the electronic density of states increases near the Fermi level by shifting valence band electrons upward. This leads to a reduction in the bandgap and a shift of the bandgap from the ultraviolet to the visible region. The examination of mechanical properties indicates that FrQCl3 (Q = Ca, Sr) perovskite exhibits significant potential for uses requiring a combination of anisotropic, and ductile behavior. Optical property analysis reveals that with an increase in hydrostatic pressure, dielectric constant's peak of both material shift towards lower photon energy area.

Why does the Milky Way have a metallicity floor?

ABSTRACT The prevalence of light element enhancement in the most metal-poor stars is potentially an indication that the Milky Way has a metallicity floor for star formation around $\sim 10^{-3.5}$ Z$_{\odot }$. We propose that this metallicity floor has its origins in metal-enriched star formation in the minihaloes present during the Galaxy’s initial formation. To arrive at this conclusion, we analyse a cosmological radiation hydrodynamics simulation that follows the concurrent evolution of multiple Population III star-forming minihaloes. The main driver for the central gas within minihaloes is the steady increase in hydrostatic pressure as the haloes grow. We incorporate this insight into a hybrid one-zone model that switches between pressure-confined and modified free-fall modes to evolve the gas density with time according to the ratio of the free-fall and sound-crossing time-scales. This model is able to accurately reproduce the density and chemo-thermal evolution of the gas in each of the simulated minihaloes up to the point of runaway collapse. We then use this model to investigate how the gas responds to the absence of H$_{2}$. Without metals, the central gas becomes increasingly stable against collapse as it grows to the atomic cooling limit. When metals are present in the halo at a level of $\sim 10^{-3.7}$ Z$_{\odot }$, however, the gas is able to achieve gravitational instability while still in the minihalo regime. Thus, we conclude that the Galaxy’s metallicity floor is set by the balance within minihaloes of gas-phase metal cooling and the radiation background associated with its early formation environment.

The Stamping Method Utilizing a Double-Trough Die in Microforming to Enhance Formability.

Currently, the field of microgear manufacturing faces various processing challenges, particularly in terms of size reduction; these challenges increase the complexity and costs of manufacturing. In this study, a technique for microgear manufacturing is aimed at reducing subsequent processing steps and enhancing material utilization. This technique involves the use of trough dies with extrusion-cutting processing, which enables workpieces to undergo forming in a negative clearance state, thus reducing subsequent processing time for micro products. We conducted finite element simulations using microgear dies, measuring stress, velocity, and flow during the forming process of four types of dies-flat, internal-trough, external-trough, and double-trough dies. The results indicated that the buffering effect of the troughs reduced the rate of increase in the material's internal stress. In the cavity, the material experiences a significant increase in hydrostatic pressure, leading to the formation of a "hydrostatic pressure wall". This pressure barrier imposes substantial constraints on the flow of the material during dynamic processes, making it difficult for the material to move into the remaining areas. This effectively enhances the blockage of material flow, demonstrating the critical role of hydrostatic pressure in controlling material distribution and movement. In addition, combining the characteristics of both into a double-trough die enhances the overall stability of forming velocity, reduces forming load and energy consumption, and maximizes material utilization. Results further revealed that microgears manufactured using double-trough dies exhibited defect-free surfaces, with a dimensional error of less than 5 μm and tolerances ranging from IT5 to IT6. Overall, this study offers new insights into the traditional field of microgear manufacturing, highlighting potential solutions for the challenges encountered in current microstamping processes.

Well-controlled mucosal exudation of plasma proteins in airways with intact and regenerating epithelium.

Superficial, systemic microcirculations, distinct from the pulmonary circulation, supply the mucosae of human nasal and conducting airways. Non-injurious, inflammatory challenges of the airway mucosa cause extravasation without overt mucosal oedema. Instead, likely reflecting minimal increases in basolateral hydrostatic pressure, circulating proteins/peptides of all sizes are transmitted paracellularly across the juxtaposed epithelial barrier. Thus, small volumes of extravasated, unfiltered bulk plasma appear on the mucosal surface at nasal and bronchial sites of challenge. Importantly, the plasma-exuding mucosa maintains barrier integrity against penetrability of inhaled molecules. Thus, one-way epithelial penetrability, strict localization, and well-controlled magnitude and duration are basic characteristics of the plasma exudation response in human intact airways. Invivo experiments in human-like airways demonstrate that local plasma exudation is also induced by non-sanguineous removal of epithelium over an intact basement membrane. This humoral response results in a protective, repair-promoting barrier kept together by a fibrin-fibronectin net. Plasma exudation stops once the provisional barrier is substituted by a new cellular cover consisting of speedily migrating repair cells, which may emanate from all types of epithelial cells bordering the denuded patch. Exuded plasma on the surface of human airways reflects physiological microvascular-epithelial cooperation in first line mucosal defense at sites of intact and regenerating epithelium.

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.

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.

Pemberian Terapi Angle Pump Exercise Dan Elevasi 30⁰ Untuk Mengurangi Edema Pada Pasien CKD

Chronic Kidney Disease (CKD) is a condition in which kidney function decreases so that it is no longer able to filtrate the body's metabolic waste and maintain electrolyte fluid balance. In CKD an increased amount of fluid can result in edema. Edema is a condition of blocked veins due to an increase in intravascular hydrostatic pressure that causes enlargement or buildup of plasma fluid into the interstitium space. Therapy that can be applied to reduce edema in CKD is with Ankle Pump Exercise and Elevation 30⁰. This therapy is done by pumping the ankle and elevating the foot for 5-10 minutes. The goal of this study was to identify Ankle Pump Exercise and 30⁰ Elevation interventions to reduce edema in CKD patients in the ICU. The type / research design used is a descriptive method with a case study approach. The subjects of this case study were patients who met the inclusion criteria, namely patients with edema and were willing to be respondents. The data collection instrument uses the format of Nursing Care. The results of this study showed that Ankle Pump Exercise and 30⁰ Elevation interventions effectively reduced edema in CKD patients. Based on the results of the case study, it can be concluded that the application of a combination therapy of ankle pump exercise and 30⁰ foot elevais has been proven effective in reducing the degree of edema in Chronic Kidney Disease (CKD) patients.

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.