Hydrostatic Pressure Research Articles

Influence of phase transition on the mechanical and optical properties of SrSe and SrTe compounds via ab initio calculations

Elastic and optical properties of strontium chalcogenides SrX (X = Se and Te) were studied under hydrostatic pressure using the flat wave method (PP-PW) implemented in the CASTEP code. The main parameter carried out was the pressure impact at ambient conditions. Indeed, under high pressures, both compounds have undergone a structural phase transition from B1 to B2 phases at ∼15.5 GPa and ∼12 GPa, respectively. Results also showed that in the B2 phase, the two postulated compounds have changed their electronic nature to become metals at metallic pressures equal to ∼16.8 GPa (SrSe) and ∼17.7 GPa (SrTe). Also, the elastic properties were calculated at different pressure values in NaCl and CsCl structures, including their elastic constants as a function of pressure for SrSe and SrTe. Their optical properties were also computed from the spectral data obtained through their dielectric function, refractive index (2.1, 2.3) and others in the visible range.

Author Correction: Establishing safe high hydrostatic pressure devitalization thresholds for autologous head and neck cancer vaccination and reconstruction

Author Correction: Establishing safe high hydrostatic pressure devitalization thresholds for autologous head and neck cancer vaccination and reconstruction

Emergence of topological phase and non-trivial surface states in rare-earth semimetal GdSb with pressure

Abstract We study the evolution of band topology under external pressure in rare-earth gadolinium mono-antimonide (GdSb) using first-principles calculations. This material crystallizes in a rocksalt-type structure and shows a structural phase transition (SPT) to a CsCl-type structure at 26.1 GPa. The phonon dispersions are analyzed to ascertain the dynamical stability of this material. We use hybrid density functional theory with the inclusion of spin–orbit coupling to investigate the structural, electronic, and topological phase transitions (TPTs). At ambient pressure, GdSb shows a topologically trivial state which is in agreement with existing experimental reports. The first TPT is observed at 6 GPa of hydrostatic pressure (at the high symmetry X-point) which is verified with the help of single-band inversion and surface state analysis along the (001) plane. The non-zero value of the first Z2 topological invariant and the presence of the Dirac cone also confirm the topological phase of this material. A further increase in pressure to 12 GPa results in two band inversions at Γ- as well as X-points, which corresponds to the trivial nature of GdSb. The same is also verified with (0; 000) values of Z2 topological invariants and a pair of Dirac cones in surface states. It is noted that the crystal symmetries are preserved throughout the study and the TPT values are much lower than the SPT pressure, i.e. 26.1 GPa.

Enhanced antioxidant activities, polyphenols, flavonoids, and free amino acid contents of Nelumbo nucifera bee pollen via high hydrostatic pressure treatment

ABSTRACT The aim of the present study was to address the effect of high hydrostatic pressure (HHP) on bioactive compounds and antioxidant activity of Nelumbo nucifera (Lotus) bee pollen (LBP). The total phenolic contents (TPC) and free amino acids were determined and flavonoid composition was identified by UPLC-Triple-TOF-MS. Five analytical methods including DPPH, ABTS, reducing power, FRAP, and silver nanoparticles antioxidant capacity were used for the antioxidant activity analysis. The results revealed a significant increase in the TPC and free amino acid compositions after HHP treatment. The DPPH, ABTS, reducing power, FRAP, and AgNPAC of the extracted fractions were augmented by over 13.94, 2.9, 2.68, 85, and 2.6 times, respectively. PCA analysis showed a strong correlation between TPC, some distinct flavonoids, and antioxidant activities. These results indicated that HHP enhances the antioxidant activity of LBP via increase in amino acids, TPC, and some flavonoids such as Licoagrone, Kuwanon K, Cyanidin 3-rutinoside, etc.

The Effect of Larger Orthodontic Forces and Movement Types over a Dental Pulp and Neuro-Vascular Bundle of Lower Premolars in Intact Periodontium-A Numerical Analysis.

This numerical analysis of stress distribution in the dental pulp and neuro-vascular bundle (NVB) of lower premolars assessed the ischemic and degenerative-resorptive risks generated by 2 and 4 N during orthodontic movements (rotation, translation, tipping, intrusion and extrusion) in intact periodontium. The numerical analysis was performed on nine intact periodontium 3D models of the second lower premolar of nine patients totaling 90 simulations. In intact periodontium, both forces displayed a similar stress distribution for all five orthodontic movements but different amounts of stress (a doubling for 4 N when compared with 2 N), with the highest values displayed in NVB. In intact periodontium, 2 N and 4 N induced stresses lower than the maximum hydrostatic pressure (MHP) with no ischemic risks for healthy intact teeth. The rotation was seen as the most stressful movement, closely followed by intrusion and extrusion. Translation was quantitatively seen as the least stressful when compared with other movements. Larger orthodontic forces of 2 N and 4 N are safe (with any expected ischemic or resorptive risks) for the dental pulp and NVB of healthy intact teeth and in intact periodontium. Nevertheless, rotation and translation movements can induce localized circulatory disturbances in coronal pulp (i.e., vestibular and proximal sides) generating ischemic and resorptive risks on previously treated teeth (i.e., direct and indirect dental pulp capping). The intrusion and extrusion movements, due to the higher NVB-induced deformation when compared with the other three movements, could trigger circulatory disturbances followed by ischemia on previously traumatized teeth (i.e., occlusal trauma).

Device Model for a Solid‐State Barocaloric Refrigerator

Solid‐state refrigeration represents a promising alternative to vapor compression cooling systems. Solid‐state devices based on magnetocaloric, electrocaloric, and elastocaloric effects have demonstrated the ability to achieve high‐efficiency, reliable, and environment‐friendly refrigeration. Cooling devices based on the barocaloric (BC) effect—entropy change due to applied hydrostatic pressure, however, has not yet been realized despite the significant promise shown in material‐level studies. As a step toward demonstrating a practical cooling system, this work presents a thermodynamic and heat transfer model for a BC refrigerator The model simulates transient thermal transport within the solid refrigerant and heat exchange with hot and cold thermal reservoirs during reversed Brayton refrigeration cycle operation. The model is used to evaluate the specific cooling power (SCP) and coefficient of performance (COP) of the device comprising nitrile butadiene rubber (NBR) as a representative BC refrigerant. Experimentally validated BC properties of NBR are used to quantify the contribution of different operating parameters including cycle frequency, applied pressure, operating temperatures, and heat transfer coefficient. The results show that a BC refrigerator operating with a temperature span of 2.4 K and 0.1 GPa applied pressure can achieve an SCP of 0.024 W g−1 at 10 mHz cycle frequency and a COP as high as 5.5 at 1 mHz cycle frequency—exceeding that of conventional vapor compression refrigerators. In addition, to identify key refrigerant properties, the effect of bulk modulus, thermal expansion coefficient, heat capacity, and thermal conductivity on device performance are quantified. The results highlight the trade‐off between different material properties to maximize the BC response, while minimizing mechanical work and improving thermal transport. This work demonstrates the promise of solid‐state cooling devices based on soft BC materials and provides a framework to quantify its performance at the device‐level.

Numerical simulation of open channel basaltic lava flow through topographical bends

In this study, we utilised computational fluid dynamics to investigate the behaviour of open-channel basaltic lava flows navigating bends on shield volcanoes. Our focus was on understanding the relationship between flow velocity, rheology, and bend geometry. Employing a simple Force Balance Model (FBM), which considers the equilibrium between hydrostatic pressure and centrifugal force, we accurately approximated the changes in the height of the lava’s free surface through various bend geometries. Our analysis includes examining the influence of channel depth, width, and bend radius on the flow, revealing that variations in these parameters significantly affect the flow’s vertical displacement. Additionally, the bend sector angle emerged as a critical factor, indicating a minimum angle necessary for the flow to fully develop before exiting the bend.Further, we assessed the applicability of the Shallow Water Equations (SWE) for modelling the inertial displacement of the lava flow in bends, finding a good fit. The study extended to comparing the FBM’s predictions of the tilt angle of the flow’s free surface with the SWE results, showing notable agreement under specific conditions, particularly at a bend angle of 90 degrees. The impact of fluid density was also considered, revealing that density is a contributing factor to the development of the wetted line in the bend, a factor that is not captured by the simple FBM model. Finally, we explored different rheologies akin to natural lava flows, such as viscoplastic flow, and determined that factors like yield stress, consistency index, and power law index have a small impact on the flow behaviour in a steady-state condition within a bend.

Recent advances in cancer detection using dynamic, stimuli-responsive supramolecular chemosensors. a focus review.

In current chemistry, supramolecular materials that respond to a wide variety of external stimuli, such as solvents, temperature, light excitation, pH, and mechanical forces (pressure, stress, strain, and tension), have attracted considerable attention; for example, we have developed cyclodextrins, cucurbiturils, pillararenes, calixarenes, crown ether-based chemical sensors, or chemosensors. These supramolecular chemosensors have potential applications in imaging, probing, and cancer detection. Recently, we focused on pressure, particularly solution-state hydrostatic pressure, from the viewpoint of cancer therapy. This Mini Review summarizes (i) why hydrostatic pressure is important, particularly in biology, and (ii) what we can do using hydrostatic pressure stimulation.

Skill building in freediving as an example of embodied culture.

Skilled activity is a complex mix of automatized action, changed attention patterns, cognitive strategies and physiological adaptations developed within a community of practice. Drawing on physiological and ethnographic research on freediving, this article argues that skill acquisition demonstrates the variety of mechanisms that link biological and cultural processes to produce culturally shaped forms of embodiment. In particular, apneists alter phenotypic expression through patterned practices that canalize development, exaggerating the dive response, developing resistance to elevated carbon dioxide levels (hypercapnia) and accommodating hydrostatic pressure at depth. The community of divers provides technical advice and helps to orient individuals' motivations. Some biological processes are phenomenologically accessible, but others are sub-aware and must be accessed indirectly through behaviour or altered interactions with the environment. The close analysis of embodied skills like freediving illustrates how phenotypic plasticity is inflected by culturally patterned behaviours. Divers do developmental work on bodily traits like the dive response to achieve more dramatic performance, even if they cannot directly control all elements of the neurological and physiological responses. The example of expert freediving illustrates the imbrication of biology and culture in embodiment. This article is part of the theme issue 'Minds in movement: embodied cognition in the age of artificial intelligence'.

Chromosomal aberrations and early mortality in a non-mammalian vertebrate: example from pressure-induced triploid Atlantic salmon.

In commercial aquaculture, the production of triploid fish is currently the most practical approach to prevent maturation and farm-to-wild introgression following escapes. However, triploids often exhibit poor welfare, and the underlying mechanisms remain unclear. Inheritance issues associated with sub-optimal hydrostatic pressure treatments used to induce triploidy, or the genetic background of parental fish, have been speculated to contribute. We tested this by quantifying the frequency and type of chromosomal aberrations in Atlantic salmon subjected to a gradient of sub-optimal pressure treatments (Experiment 1) and from multiple mothers (Experiment 2). From these experiments, we genotyped a subsample of ~900 eyed eggs and all ~3300 surviving parr across ~20 microsatellites. In contrast to the low frequency of chromosomal aberrations in the diploid (no hydrostatic pressure) and triploid (full 9500 PSI treatment) controls, eyed eggs subjected to sub-optimal pressure treatments (6500-8500 PSI) had a higher incidence of chromosomal aberrations such as aneuploidy and uniparental disomy, corresponding to lower triploidization success and higher egg mortality rates. We also observed maternal effects on triploidization success and incidence of chromosomal aberrations, with certain half-sibling families exhibiting more aberrations than others. Chromosomal aberrations were rare among surviving parr, suggesting a purge of maladapted individuals during early development. This study demonstrates that sub-optimal hydrostatic pressure treatments and maternal effects not only influence the success of triploidization treatments, but may also affect the incidence of chromosomal aberrations and early mortality. The results have important implications for aquaculture breeding programs and their efforts to prevent farm-to-wild introgression.

Signature of pressure-induced topological phase transition in ZrTe5

The layered van der Waals material ZrTe5 is known as a candidate topological insulator (TI), however its topological phase and the relation with other properties such as an apparent Dirac semimetallic state is still a subject of debate. We employ a semiclassical multicarrier transport (MCT) model to analyze the magnetotransport of ZrTe5 nanodevices at hydrostatic pressures up to 2 GPa. The temperature dependence of the MCT results between 10 and 300 K is assessed in the context of thermal activation, and we obtain the positions of conduction and valence band edges in the vicinity of the chemical potential. We find evidence of the closing and re-opening of the band gap with increasing pressure, which is consistent with a phase transition from weak to strong TI. This matches expectations from ab initio band structure calculations, as well as previous observations that CVT-grown ZrTe5 is a weak TI in ambient conditions.

A DFT study of the effect of hydrostatic pressure on the structure and electronic properties of sarcosine crystal

ContextWe perform density functional theory calculations to study the dependence of the structural and electronic properties of the amino acid sarcosine crystal structure on hydrostatic pressure application. The results are analyzed and compared with the available experimental data. Our findings indicate that the crystal structure and properties of sarcosine calculated using the Grimme dispersion-corrected PBE functional (PBE-D3) best agree with the available experimental results under hydrostatic pressure of up to 3.7 GPa. Critical structural rearrangements, such as unit cell compression, head-to-tail compression, and molecular rotations, are investigated and elucidated in the context of experimental findings. Band gap energy tuning and density of state shifts indicative of band dispersion are presented concerning the structural changes arising from the elevated pressure. The calculated properties indicate that sarcosine holds great promise for application in electronic devices that involve pressure-induced structural changes.MethodsThree widely used generalized gradient approximation functionals—PBE, PBEsol, and revPBE—are employed with Grimme’s D3 dispersion correction. The non-local van der Waals density functional vdW-DF is also evaluated. The calculations are performed using the projector-augmented wave method in the Quantum Espresso software suite. The geometry optimization results are visualized using VMD. The Multiwfn and NCIPlot programs are used for wavefunction and intermolecular interaction analyses.

Modeling and Characterization of Li-Ion 18650 Nickel–Cobalt–Alumina Battery Jellyroll Subjected to Static and Dynamic Compression Loading

This study presents a comprehensive experimental investigation of the mechanical response of the jellyroll and complete Li-ion 18650 Nickel–Cobalt–Alumina (NCA) battery under axial compression, highlighting the effects of strain rate and state-of-charge (SOC). The jellyroll was subjected to both static (1 mm/min) and dynamic (10–30 m/s) axial compression using a Split-Hopkinson Pressure Bar (SHPB). A key innovation of this work is the investigation of the role of electrolytes under both static and dynamic conditions, revealing their significant impact on stress and strain behavior due to hydrostatic pressure. Additionally, the complete NCA battery was tested under various SOC levels (0–75%) using flat plate compression. The results demonstrate the jellyroll’s sensitivity to strain rate, with increased stress responses at higher loading speeds. Furthermore, the inclusion of electrolytes markedly amplified the stress and strain response. The Fu-Chang model was successfully employed to numerically replicate the observed static and dynamic behaviors. Critically, the full battery tests revealed a negative correlation between voltage cutoff and SOC, with the risk of fire and explosion increasing at higher SOC levels. This research provides novel insights into the safety and mechanical resilience of Li-ion batteries under compression.

Determining the effect of high hydrostatic pressure on the refrigerated stability of avocado puree

The present study aimed to extend refrigerated stability of locally grown avocado fruit by applying High Hydrostatic Pressure (HHP) treatment. HHP was applied at 600 MPa for 3 min to avocado puree and stored at 4 °C for 28 days. Physicochemical (colour CIE L*, a*, b*, total oil amount, chlorophyll, pH, moisture) and microbiological (mesophilic, yeast-mould) analyses were performed at seven-day intervals on both control (untreated) and HHP-treated sample packs. It could be judged that HHP treatment effectively controlled the colour indices, preventing undesired changes during the cold storage period of avocado puree. In conclusion, this study demonstrated that HHP-processed avocado puree exhibited stability for 28 days compared to unprocessed puree at 4 °C. The shelf-life stability of avocado puree under chilled conditions was extended from 7 to 28 days.Graphical

Ionic selectivity of nanopores: Comparison among cases under the hydrostatic pressure, electric field, and concentration gradient

The ionic selectivity of nanopores is crucial for the energy conversion based on nanoporous membranes. It can be significantly affected by various parameters of nanopores and the applied fields driving ions through porous membranes. Here, with finite element simulations, the selective transport of ions through nanopores is systematically investigated under three common fields, i.e. the electric field (V), hydrostatic pressure (p), and concentration gradient (c). For negatively charged nanopores, through the quantitative comparison of the cation selectivity (t+) under the three fields, the cation selectivity of nanopores follows the order of t+V > t+c > t+p. This is due to the transport characteristics of cations and anions through the nanopores. Because of the strong transport of counterions in electric double layers under electric fields and concentration gradients, the nanopore exhibits a relatively higher selectivity to counterions. We also explored the modulation of t+ on the properties of nanopores and solutions. Under all three fields, t+ is directly proportional to the pore length and surface charge density, and inversely correlated to the pore diameter and salt concentration. Under both the electric field and hydrostatic pressure, t+ has almost no dependence on the applied field strength or ion species, which can affect t+ in the case of the concentration gradient. Our results provide detailed insights into the comparison and regulation of ionic selectivity of nanopores under three fields which can be useful for the design of high-performance devices for energy conversion based on nanoporous membranes.

Enhancing Resistance to Wetting Transition through the Concave Structures.

Water-repellent superhydrophobic surfaces are ubiquitous in nature. The fundamental understanding of bio/bio-inspired structures facilitates practical applications surmounting metastable superhydrophobicity. Typically, the hierarchical structure and/or reentrant morphology have been employed hitherto to suppress the Cassie-Baxter to Wenzel transition (CWT). Herein, a new design concept is reported, an effect of concave structure, which is vital for the stable superhydrophobic surface. The thermodynamic and kinetic stabilities of the concave pillars are evaluated by continuous exposure to various hydrostatic pressures and sudden impacts of water droplets with various Weber numbers (We), comparing them to the standard superhydrophobic normal pillars. Specifically, the concave pillar exhibits reinforced impact resistance preventing CWT below a critical We of ≈27.6, which is ≈1.6 times higher than that of the normal pillar (≈17.0). Subsequently, the stability of underwater air film (plastron) is investigated at various hydrostatic pressures. The results show that convex air caps formed at the concave cavities generate downward Laplace pressure opposing the exerted hydrostatic pressure between the pillars, thus impeding the hydrostatic pressure-dependent underwater air diffusion. Hence, the effects of trapped air caps contributing to the stable Cassie-Baxter state can offer a pioneering strategy for the exploration and utilization of superhydrophobic surfaces.

Bulk high-temperature superconductivity in pressurized tetragonal La2PrNi2O7.

The Ruddlesden-Popper (R-P) bilayer nickelate, La3Ni2O7, was recently found to show signatures of high-temperature superconductivity (HTSC) at pressures above 14 GPa (ref. 1). Subsequent investigations achieved zero resistance in single-crystalline and polycrystalline samples under hydrostatic pressure conditions2-4. Yet, obvious diamagnetic signals, the other hallmark of superconductors, are still lacking owing to the filamentary nature with low superconducting volume fraction2,4,5. The presence of a new 1313 polymorph and competing R-P phases obscured proper identification of the phase for HTSC6-9. Thus, achieving bulk HTSC and identifying the phase at play are the most prominent tasks. Here we address these issues in the praseodymium (Pr)-doped La2PrNi2O7 polycrystalline samples. We find that substitutions of Pr for La effectively inhibit the intergrowth of different R-P phases, resulting in a nearly pure bilayer structure. For La2PrNi2O7, pressure-induced orthorhombic to tetragonal structural transition takes place at Pc ≈ 11 GPa, above which HTSC emerges gradually on further compression. The superconducting transition temperatures at 18-20 GPa reach and , which are the highest values, to our knowledge, among known nickelate superconductors. Importantly, bulk HTSC was testified by detecting clear diamagnetic signals below about 75 K with appreciable superconducting shielding volume fractions at a pressure of above 15 GPa. Our results not only resolve the existing controversies but also provide directions for exploring bulk HTSC in the bilayer nickelates.

Insights into pressure-driven depolarization in PLZST-based antiferroelectric ceramics

Materials showing field-driven antiferroelectric to ferroelectric transformation are interesting for the design of pyroelectric, high strain actuator and high-power dielectric energy storage and discharge devices. The stability of the antiferroelectric and ferroelectric states at room temperature can be chemically tuned by La and Ti co-modification of the antiferroelectric system Pb(Zr1-ySny)O3. Here, we have chosen a composition Pb0.982La0.012(Zr0.60Sn0.30Ti0.10)O3 (PLZST) at the threshold of the antiferroelectric-ferroelectric instability at room temperature and investigated the effect of electric field, temperature and pressure on the stability of the structural-polar states. We show that electric poling transforms irreversibly the antiferroelectric state into a ferroelectric state. Application of hydrostatic pressure ∼100 MPa on the field-stabilized ferroelectric phase, however, restores the antiferroelectric state and depolarizes the system.

Effects of hydrostatic pressure, osmotic pressure, and confinement on extracellular matrix associated responses in the nucleus pulposus cells ex vivo

Spinal movement in both upright and recumbent positions generates changes in physicochemical stresses including hydrostatic pressure (HP), deviatoric stress, and confinement within the intradiscal compartment. The nucleus pulposus (NP) of the intervertebral disc is composed of highly negatively charged extracellular matrix (ECM), which increases osmotic pressure (OP) and generates tissue swelling. In pursuing regenerative therapies for intervertebral disc degeneration, the effects of HP on the cellular responses of NP cells and the ECM environment remain incompletely understood. We hypothesized that anabolic turnover of ECM in NP tissue is maintained under HP and confinement. We first clarified the effects of the relationships among HP, OP, and confinement on swelling NP explants isolated from bovine caudal intervertebral discs over 12 hours. We found that the application of confinement and constant HP significantly inhibits the free swelling of NP (p < 0.01) and helps retain the sulfated glycosaminoglycan. Since confinement and HP inhibited swelling, we incubated confined NPs under HP in high-osmolality medium mimicking ECM-associated OP for 7 days and demonstrated the effects of HP on metabolic turnover of ECM molecules in NP cells. The aggrecan core protein gene was significantly upregulated under confinement and constant HP compared to confinement and no HP (p < 0.01). We also found that confinement and constant HP helped to significantly retain smaller cell area (p < 0.01) and significantly prevent the severing of actin filaments compared to no confinement and HP (p < 0.01). Thus, we suggest that NP's metabolic turnover and cellular responses are regulated by the configuration of intracellular actin and fibrillar ECMs under HP.

Simulation of the pulsed streamer discharge in water considering the effect of hydrostatic pressure

Streamer discharge is a very complex multi-scale and multi-physics coupling process, and there is no accurate model that can describe its development. In this paper, a two-dimensional axisymmetric fluid model is established in COMSOL to simulate and study the effects of the applied voltage amplitude, the discharge gap distance, the rising edge of pulse voltage, and hydrostatic pressure on the development of the positive streamer discharge at a needle-plate electrode in water under a nanosecond pulse voltage. The results show that increasing the voltage amplitude, decreasing the pulse rise time, and narrowing the discharge gap all increase the electric field strength of the streamer, thereby affecting the electron density of the plasma channel, among which changing the discharge gap has the greatest effect on the electron density. And under the gap of 3 mm, the peak electron density can reach 3.76 × 1023 m−3; if the discharge gap is narrowed to 1 mm, the peak electron density is reduced to 1.20 × 1023 m−3. In addition, hydrostatic pressure and water molecule spacing are closely linked. Increasing the hydrostatic pressure decreases the electric field strength and the peak electron density in the plasma channel, and its effect on the peak electron density saturates with increasing hydrostatic pressure.