Effect Of Hydrostatic Pressure Research Articles

Dynamics of the nonlinear optical second, and third harmonic generation in GaAs/Ga0.7Al0.3As quantum well due to hydrostatic pressure and temperature

Abstract We studied the effects of hydrostatic pressure and temperature on the second and third harmonic generation (SHG and THG) of nonlinear optics semi-parabolic GaAs/Al0.3Ga0.7As quantum well. By solving the Schrödinger equation numerically, we can determine the system's subband energy levels and propagation wave functions, and then calculate its optical gain. The numerical simulation results show that both temperature and hydrostatic pressure can effectively improve the nonlinear optical performance of the system. As an interesting observation, we studied the mechanism of the two in this process. These findings highlight a feasible method to adjust the nonlinear optical performance of GaAs/Al0.3Ga0.7As quantum system through the subtle interaction between hydrostatic pressure, temperature and structural parameters.

Observation of Hydrostatic‐Pressure‐Modulated Giant Caloric Effect and Electronic Topological Transition

AbstractPhase transition is a fundamental phenomenon in condensed matter physics, in which states of matter transform to each other with various critical behaviors under different conditions. The magnetic martensitic transformation features significant multi‐caloric effects that benefit the solid‐state cooling or heat pumping. Meanwhile, the electronic topological transition (ETT) driven by pressure has been rarely reported in martensitic systems. Here, the modulation effects of hydrostatic pressure on phase transitions in a magnetic martensitic alloy are reported. Owing to the huge volume expansion during the transition, the martensitic transition temperature is driven from 339 to 273 K by pressure within 1 GPa, resulting in highly tunable giant baro‐ and magneto‐caloric effects (BCE and MCE) in a wide working temperature range. Interestingly, an ETT is further induced by pressure in the martensite phase, with a sudden drop of the measured saturation magnetization around 0.6 GPa. First‐principles calculations reveal a sharp change in the density of states (DOS) due to the orbit shift around the Fermi level at the same pressure and reproduce the experimental observation of magnetization. Besides, the ETT is accompanied by remarkable changes in the lattice parameters and the unit‐cell orthorhombicity. The study provides insight into pressure‐modulated exotic phase‐transition phenomena in magnetic martensitic systems.

Synergistic effects of superfine grinding and high hydrostatic pressure on the contents, distribution, digestive behaviors and antioxidant activities of polyphenols in barley leaves

Barley leaves (BLs) naturally contained abundant phenolics, most of which are hardly completely released from food matrix during gastrointestinal digestion. Superfine grinding (SFG) and high hydrostatic pressure (HHP) are generally used to treat the functional plants due to their effectiveness to cell wall-breaking and improvement of nutraceutical bioavailability. Thus, this study investigated the synergistic effects of SFG and HHP (100, 300, 500 MPa/20 min) on the bioaccessbility of typical phenolics in BLs during the simulated in-vitro digestion. The results demonstrated that the highest bioaccessbility (40.98%) was found in the ultrafine sample with HHP at 500 MPa. CLSM and SEM confirmed SFG led to microstructurally rapture of BLs. Moreover, the recovery index of ABTS radical scavenging activity and FRAP of HHP-treated ultrafine and fine BLs samples maximumly increased by 53.62% and 9.61%, respectively. This study is expecting to provide the theoretical basis to improve the consumer acceptance of BLs.

Exploring high hydrostatic pressure effects on anthocyanin binding to serum albumin and food-derived transferrins

This study investigated the effects of high hydrostatic pressure (HHP) on the binding interactions of cyanindin-3-O-glucoside (C3G) to bovine serum albumin, human serum albumin (HSA), bovine lactoferrin, and ovotransferrin. Fluorescence quenching revealed that HHP reduced C3G-binding affinity to HSA, while having a largely unaffected role for the other proteins. Notably, pretreating HSA at 500 MPa significantly increased its dissociation constant with C3G from 24.7 to 34.3 μM. Spectroscopic techniques suggested that HSA underwent relatively pronounced tertiary structural alterations after HHP treatments. The C3G-HSA binding mechanisms under pressure were further analyzed through molecular dynamics simulation. The localized structural changes in HSA under pressure might weaken its interaction with C3G, particularly polar interactions such as hydrogen bonds and electrostatic forces, consequently leading to a decreased binding affinity. Overall, the importance of pressure-induced structural alterations in proteins influencing their binding with anthocyanins was highlighted, contributing to optimizing HHP processing for anthocyanin-based products.

Effect of soaking solution and high hydrostatic pressure on in vitro digestibility of β-carotene in gluten free sweet potato noodles

Current work aimed to examine the influence of soaking solution (citric acid, calcium chloride and ascorbic acid) and high hydrostatic pressure (100, 200 and 400 MPa) on gelatinization properties of flour and antioxidant activity alongwith in vitro- digestibility of β-carotene in orange-fleshed sweet potato flour (OSPF) noodles. With the intensity of the HHP application, water absorption capacity increased linearly whereas water swelling capacity decreased in OSPF. Differential scanning calorimetry (DSC) of OSPF indicated a remarkable reduction in peak enthalpy due to gelatinization of starch and denaturation of protein. Hardness and cohesion of OSPF noodles at 400 MPa remarkably decreased whereas springiness increased. Antioxidant capacities of OSPF was gradually increased with the 400 MPa and ascorbic acid-treated OSPF due to the immense contribution of higher contents of TPC. After in vitro digestibility, noodles from OSPF prepared with 400 MPa treated flour exhibited maximum β-carotene retention. Thus, OSPF treated with 400 MPa might be potentially used for the production of noodles with acceptable texture and functional properties.

Effect of hydrostatic pressure on the anodic dissolution process of X80 steel

Based on the fact that hydrostatic pressure affects chemical potentials of reaction species and the structure evolution of electric double layer (EDL), the authors propose a generalized-BV equation to analyze the anodic dissolution process of X80 steel in deep-sea environment. Combined with the results of potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests, the following conclusions can be drawn: hydrostatic pressure can compress the electric double layer non-uniformly. The CHCD (CD: capacitance of diffused layer; CH: capacitance of compact layer) value increases first and then decreases with increasing hydrostatic pressure and reaches its maximum at 15 MPa, which is sure to influence the difference in electrical potential that drives chemical reaction at interface. Ultimately, the anodic dissolution current increases and then decreases with rising hydrostatic pressure at the same anodic polarized potential. Besides, low hydrostatic pressure may contribute to forming a dense corrosion product film and inducing a good inhibiting effect on further dissolution of X80 steel; However, when the hydrostatic pressure exceeds the critical value of 20Mpa, too high anodic dissolution rate along with promoted Cl− adsorption will deteriorate the protection performance of corrosion product film, and exacerbate local corrosion process.

A two-phase flow model for sedimentation and consolidation

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.

Simulated Hydrostatic Pulpal Pressure Effect on Microleakage-An Initial Study.

This study's purpose was to evaluate the effect of simulated in vitro hydrostatic pulpal pressure (HPP) on microleakage. Extracted third molars (n=12) were sectioned 5 mm below the cementoenamel junction, pulp tissue removed, and the sectioned crowns mounted on a Plexiglas plate penetrated by an 18-gauge stainless steel tube. The mounted specimen mesial surface received a 2×4×6 mm Class V preparation followed by restoration with a strongly acidic, one-step dental adhesive and a flowable microfilled resin, following all manufacturers' instructions. Restorations were finished to contour, and tubing was attached to a 20-cm elevated, 0.2% rhodamine G reservoir to the specimen steel tube for 48 hours. Specimens then received a nail polish coating to within 1 mm of the restoration margins and were placed in 2% methylene blue (MB) dye for 24 hours, followed by rinsing, embedding in epoxy resin, and sectioning into 1 mm slices using a diamond saw. Controls were intact molars (n=12) processed as above but without HPP. Specimen slices were evaluated using laser confocal microscopy with images exported to ImageJ software with microleakage assessed as the MB linear penetration as a percentage of the total interfacial wall length. Mean values were evaluated with the Kruskal Wallis/Dunn test at a 95% confidence level. The control specimens demonstrated significantly greater (p<0.0001) MB penetration than experimental specimens with simulated HPP. Under this study's conditions, simulated HPP significantly decreased MB dye penetration. Studies accomplished without simulated HPP may overestimate microleakage results.

Lightweight, hydrostatic pressure‐resistance, thermal insulating epoxy syntactic foam with a multiscale ternary structure for marine engineering application

AbstractThe study of lightweight epoxy syntactic foams is of great significance for the exploitation of marine resources. In this work, glass fibers reinforced epoxy hollow spheres (GFs‐EHS) were first prepared using a template method, and a lightweight three‐phase epoxy syntactic foam (LWTP‐ESF) with a multiscale ternary structure was prepared using a molding pressing method with epoxy resin as matrix, hollow glass microspheres (HGMs), and GF‐EHS as the lightweight fillers. The effect of HGMs content on the density, uniaxial compression properties, water absorption, and thermal conductivity of obtained LWTP‐ESF was evaluated. The results indicated that the density, uniaxial compression strength, and thermal conductivity of LWTP‐ESF were consistently decreased, while the water absorption was increased with the increase in HGMs content. The highest specific compression strength and lowest thermal conductivity of LWTP‐ESF could reach 52.77 ± 0.82 MPa·cm3/g and 0.113 ± 0.005 W/(m·K), respectively. Moreover, the effect of hydrostatic pressure on the water absorption and thermal conductivity of LWTP‐ESF were also systematically analyzed. This study provides a novel system and method to prepare lightweight epoxy syntactic foams, and the prepared composites have potential applications in the field of lightweight thermal insulation materials for marine.Highlights The composites with a multiscale ternary structure were designed. The composites possessed significantly lower density and thermal conductivity. The water absorption of composites under hydrostatic pressure was evaluated. The thermal conductivity of composites under hydrostatic pressure was evaluated. The water absorption mechanism and thermal insulation mechanism were proposed.

Studying the Effects of Dissolved Noble Gases and High Hydrostatic Pressure on the Spherical DOPC Bilayer Using Molecular Dynamic Simulations.

Fine-grained molecular dynamics simulations have been conducted to depict lipid objects enclosed in water and interacting with a series of noble gases dissolved in the medium. The simple point-charge (SPC) water system, featuring a boundary composed of 1,2-Dioleoyl-sn-glycero-3-phosphocholine (DOPC) molecules, maintained stability throughout the simulation under standard conditions. This allowed for the accurate modeling of the effects of hydrostatic pressure at an ambient pressure of 25 bar. The chosen pressure references the 240 m depth of seawater: the horizon frequently used by commercial divers, who comprise the primary patient population of the neurological complication of inert gas narcosis and the consequences of high-pressure neurological syndrome. To quantify and validate the neurological effects of noble gases and discriminate them from high hydrostatic pressure, we reduced the dissolved gas molar concentration to 1.5%, three times smaller than what we previously tested for the planar bilayer (3.5%). The nucleation and growth of xenon, argon and neon nanobubbles proved consistent with the data from the planar bilayer simulations. On the other hand, hyperbaric helium induces only a residual distorting effect on the liposome, with no significant condensed gas fraction observed within the hydrophobic core. The bubbles were distributed over a large volume-both in the bulk solvent and in the lipid phase-thereby causing substantial membrane distortion. This finding serves as evidence of the validity of the multisite distortion hypothesis for the neurological effect of inert gases at high pressure.

DFT insights into the pressure-induced ultraviolet to visible band gap engineering of TlMgF3 cubic halide perovskites for optoelectronic applications

The current study utilizes first-principle calculation in order to investigate the geometrical, electrical, mechanical, and optical characteristics of TlMgF3 cubic halide perovskites under the effect of hydrostatic pressure. The interatomic distance is significantly reduced, causing a substantial decrease in the unit cell volume and lattice constant of TlMgF3 perovskite. The electronic energy band gap undergoes a transition from the UV to the visible region in response to the hydrostatic pressure, thereby allowing electron transport from the valence band to the conduction band. This causes some interesting observations in the electronic and optical characteristics of many optoelectronic devices. Additionally, at approximately 500 GPa pressure, the direct band gap is tuned from 4.275 eV to 1.66 eV, making the material suitable for use in solar cell applications. Deep optical analysis has recommended the utilization of TlMgF3 in numerous other applications, including microelectronics, QLED (quantum dot light-emitting diode), OLED (organic light-emitting diode), solar heat reduction materials, and surgical instruments. When external hydrostatic pressure is applied, the mechanical properties of the material are also substantially altered, resulting in increased flexibility and anisotropy.

Experimental study on local scour protection and contact pressure of the facing water surface at the pier based on the guide pillar

The safety of pier foundations is an important issue in bridge construction, where local bridge scour is a major cause of bridge damage worldwide, exacerbated by ice sheets. This paper offers a live bed scour experimental investigation that assesses the impacts of the new anti-scour device guide pillar of different sizes on geometric properties of scour, downflow velocity distribution, and turbulence intensity around the pier under different flow velocities and roughnesses, and to select the optimum installation position and size of the guide pillar. The results demonstrate that the guide pillar has a considerable effect on the scour hole and downflow around the pier, and the maximum reduction rate of scour depth is 59.3% in the optimal installation position (2d). By arranging distributed thin-film pressure sensors on the pier and measuring the pressure distribution on the facing water surface of the pier and the position of the center of gravity, this paper analyzes the distribution characteristics of the water flow force on the pier and the impact resistance of the guide pillar to the pier scour. The study found that the guide pillar reduces the water flow force by 61.3% without considering the effect of hydrostatic pressure.

Hydrostatic pressure and temperature dependent optical properties of double inverse parabolic quantum well under the magnetic field

In this study, we investigated the combined effects of structure parameters such as size and geometry, as well as hydrostatic pressure, temperature, and magnetic field on the electronic and optical properties of a double inverse parabolic quantum well within the framework of the effective mass and parabolic band approximations. It is very important to consider the effects of temperature and hydrostatic pressure, especially in practical applications involving quantum wells such as semiconductor devices and optoelectronics. The results obtained are in good agreement with the literature. Understanding how these factors affect the electronic and optical properties of semiconductor heterostructures helps to optimize the performance and stability of devices operating under different environmental conditions.

Investigation on Low-Frequency and Broadband Sound Absorption of the Compact Anechoic Coating Considering Hydrostatic Pressure

The anechoic coating capable of absorbing sound energy in low frequencies within broadband is essential to conceal underwater vehicles. However, the geometric deformation and modification of mechanical parameters under hydrostatic pressure affect the prediction of absorption performance in deep water environments. An anechoic coating embedded with tandem resonant voids is proposed in this work to achieve quasi-perfect low-frequency and broadband absorption. The analytical method based on the effective medium approach and numerical simulation are performed to estimate the effects of hydrostatic pressure on sound absorption. When additionally considering the dynamic mechanical parameters of the compressed viscoelastic medium, the original absorption humps in low frequencies are inclined to higher band, accompanied by the expanded absorption bandwidth. Then, the tandem coating specimen is measured in a water-filled impedance tube. The experimental spectra are consistent with the analytical and numerical results under various hydrostatic pressures, demonstrating the efficient absorption (α &gt; 0.7) in broadband low frequencies via ordinary pressure. At the same time, the absorption spectrum under higher hydrostatic pressures is also verified in the tube. Consequently, this work paves the way for a broadband low-frequency underwater absorber design and provides an efficient method to characterize the low-frequency and broadband absorption from the coupled resonant coatings in deep water environments.

High hydrostatic pressure stimulates microbial nitrate reduction in hadal trench sediments under oxic conditions

Hadal trenches are extreme environments situated over 6000 m below sea surface, where enormous hydrostatic pressure affects the biochemical cycling of elements. Recent studies have indicated that hadal trenches may represent a previously overlooked source of fixed nitrogen loss; however, the mechanisms and role of hydrostatic pressure in this process are still being debated. To this end, we investigate the effects of hydrostatic pressure (0.1 to 115 MPa) on the chemical profile, microbial community structure and functions of surface sediments from the Mariana Trench using a Deep Ocean Experimental Simulator supplied with nitrate and oxygen. We observe enhanced denitrification activity at high hydrostatic pressure under oxic conditions, while the anaerobic ammonium oxidation – a previously recognized dominant nitrogen loss pathway – is not detected. Additionally, we further confirm the simultaneous occurrence of nitrate reduction and aerobic respiration using a metatranscriptomic dataset from in situ RNA-fixed sediments in the Mariana Trench. Taken together, our findings demonstrate that hydrostatic pressure can influence microbial contributions to nitrogen cycling and that the hadal trenches are a potential nitrogen loss hotspot. Knowledge of the influence of hydrostatic pressure on anaerobic processes in oxygenated surface sediments can greatly broaden our understanding of element cycling in hadal trenches.

Hydrostatic pressure and temperature effects on nonlinear optical properties in harmonic-Gaussian asymmetric double quantum wells

The paper examines the linear and non-linear optical characteristics of an electron in harmonic Gaussian asymmetrical double quantum wells, taking into account thermodynamic variables such as temperature and hydrostatic pressure. Numerical calculations by considering the effective mass and parabolic band approximation are performed. The electron contained within an asymmetric double well generated by the sum of a parabolic and Gaussian potential has its eigenvalues and eigenfunctions determined using the diagonalization approach. For nonlinear optical coefficients, the density matrix expansion is used. Wavefunctions and energy levels vary as an effect of the applied fields. In harmonic Gaussian asymmetrical double quantum wells, the total optical absorption coefficient (TOAC), the relative refractive index changes (RRIC), and second harmonic generation (SHG) have all been theoretically investigated. The magnitude and position of the resonant peaks are significantly influenced by the hydrostatic pressure and temperature effects. With controllable coupling and externally applied hydrostatic pressure and temperature, the potential model presented in this study can be used to simulate and manipulate the optical and electronic properties of the asymmetric double-quantum heterostructures, such as double quantum dots and wells.

The Effect of Hydrostatic Pressure on Coronary Flow and Pressure-Based Indices of Coronary Stenosis Severity.

Background: To assess whether hydrostatic pressure gradients caused by coronary height differences in supine versus prone positioning during invasive physiological stenosis assessment affect resting and hyperaemic pressure-based indices or coronary flow. Methods: Twenty-three coronary stenoses were assessed in twenty-one patients with stable coronary artery disease. All patients had a stenosis of at least 50% visually defined on previous coronary angiography. Pd/Pa, iFR, FFR, and coronary flow velocity (APV) measured using a Doppler were recorded across the same stenosis, with the patient in the prone position, followed by repeat measurements in the standard supine position. Results: When comparing prone to supine measurements in the same stenosis, in the LAD, there was a significant change in mean Pd/Pa of 0.08 ± 0.04 (p = 0.0006), in the iFR of 0.06 ± 0.07 (p = 0.02), and in the FFR of 0.09 ± 0.07 (p = 0.003). In the Cx, there was a change in mean Pd/Pa of 0.05 ± 0.04 (p = 0.009), iFR of 0.07 ± 0.04 (p = 0.01), and FFR of 0.05 ± 0.03 (p = 0.006). In the RCA, there was a change in Pd/Pa of 0.05 ± 0.04 (p = 0.032), iFR of 0.04 ± 0.05 (p = 0.19), and FFR of 0.04+-0.03 (p = 0.004). Resting and hyperaemic coronary flow did not change significantly (resting delta APV = 1.6 cm/s, p = 0.31; hyperaemic delta APV = 0.9 cm/s, p = 0.85). Finally, 36% of iFR measurements and 26% of FFR measurements were re-classified across an ischaemic threshold when prone and supine measurements were compared across the same stenosis. Conclusions: Pd/Pa, iFR, and FFR were affected by hydrostatic pressure variations caused by coronary height differences in prone versus supine positioning. Coronary flow did not change signifying a purely pressure-based phenomenon.

Effect of high hydrostatic pressure and thermal treatment on polyphenolic compounds and the antioxidant capacity of Phaseolus coccineus L.

AbstractBackground and ObjectivesHigh hydrostatic pressure (HHP) is a nonthermal technology that has been applied to several innovative food products, extending shelf life while preserving sensory characteristics and nutritional value. This technology is feasible to apply to legumes, like beans, to soften them and reduce preparation time. Traditionally, before bean consumption, soaking and cooking processes are carried out to develop palatability; however, this involves a loss of compounds with high biological activity such as dietary fiber, oligosaccharides, and polyphenols, which are of interest due to their antioxidant capacity and related benefits linked to a reduction in the risk of several diseases. Thus, the aim of the study was to evaluate the impact of HHP against traditional cooking on polyphenols and the antioxidant capacity of four Phaseolus coccineus L. cultivars: three Mexican (purple, brown, and white) and one Spanish (white).FindingsThere was a higher loss of polyphenols in beans where only heat treatment was applied compared to those treated by HHP. The highest antioxidant capacity (1,1‐diphenyl‐2‐picrylhydrazyl and ferric‐reducing antioxidant power) was observed in colored samples with a higher content of total polyphenols.ConclusionsThe use of HHP decreases the cooking time of beans by 15 min while preserving the polyphenol content and antioxidant properties.Significance and NoveltyHHP can be an alternative for the legume food industry, to reduce cooking time, while preserving or improving their composition and functionality.

WITHDRAWN: Investigation on corrosion behaviors of 316 stainless steel in deep-sea water/sediments of the South China Sea via manned deep diving

As observed in a 3404-meter-deep field test via manned diving, 316 SS mainly occurs pitting corrosion in deep-sea water/sediments and corrodes 3-4 times faster than that in shallow sea. In water, due to the synergistic effect of high hydrostatic pressure and Cl− ions, the passive film becomes loose and nonuniform, and the pits expand laterally, leading to wide and shallow pits. In sediments, S2− ions inhibit the re-passivation process and make the passive film thinner, causing numerous pits initiate. Because of the poor Cl− ions transfer efficiency, the pits expand slowly in lateral direction, resulting in vertical pits.

Effects of high hydrostatic pressure on the functional properties of soy protein isolate

AbstractIn this study, functional properties of high hydrostatic pressure (HHP)‐treated soy protein isolate (SPI) samples including protein solubility, emulsification activity (EA), and water holding capacity (WHC) were studied. Fourier transform infrared spectroscopy (FTIR), viscosity, and nuclear magnetic resonance (NMR) relaxometry experiments were performed. Three pressure (300, 400, and 500 MPa), two pH (5.0 and 7.0), and two temperature levels (25 and 40°C) were used to prepare SPI samples. Solubility of SPI was more pH‐dependent than HHP‐dependent, whereas WHC was more sensitive to pressure. Samples processed at 300 MPa, pH 5.0, and 40°C demonstrated higher EA (p &lt; .05) than the untreated samples. Pressure application significantly reduced the viscosity of SPI dispersions (p &lt; .05). Samples processed at 300 MPa, pH 5.0, and 40°C and at 400 MPa, pH 5.0, and 40°C attained the longest transverse relaxation time (T2) values reflecting their low solubility profiles. Thus, results indicated that HHP was able to modify the functional properties of SPI at different temperature and pH conditions.Practical ApplicationsHigh hydrostatic pressure (HHP) is an emerging technology with its diverse range of applications in food industry. Modification of functional properties of food ingredients is one of the latest applications of HHP treatment. This study demonstrated that HHP treatment was able to modify some functional properties of soy protein isolate (SPI) samples including water holding capacity, solubility, and emulsification activity. Pressure level, pH, and temperature affected the functional properties of SPI samples. The parameter type/range and results of this study could be used in model HHP studies to improve some functional properties of SPI for different purposes.