Hydrostatic Pressure Conditions Research Articles

Impact of variable hydrostatic pressure and intermittent operation on filtration performance and biofouling layer in gravity-driven membrane system for practical decentralized water supply

The gravity-driven membrane (GDM) systems offer a promising solution for decentralized drinking water supply due to its low maintenance and energy consumption. However, research on the practical application of GDM under variable hydrostatic pressure (variable load) and intermittent operation conditions, particularly in response to high-turbidity water, remains limited. This study investigates the long-term performance and characteristics of the biofouling layer of GDM under ultra-low variable hydrostatic pressure (20–60 mbar) and intermittent operation (8–12 h) conditions in practical decentralized water supply. The results indicate that the membrane flux (1.9–6.0 L∙m−2∙h−1, LMH) remained relatively stable despite variations in gravity-driven pressure (ΔP). Long-term operation of GDM can stably remove turbidity and potential pathogens from raw water. The total protein/polysaccharide ratios of extracellular polymeric substances (EPS) in the biofouling layer were below 0.50, reducing contaminant adhesion on the membrane surface. The 0.2–0.4 μm transparent exopolymer particles (TEP) fraction might be crucial for biofouling layer formation. The key species, belong to Proteobacteria and Patescibacteria, significantly alleviated membrane fouling by degrading polysaccharide and proteins in biofouling layer. Comammox Nitrospira were significantly enriched, contributing to efficient nitrification. GDM with variable load maintained a stable flux of 2.2–5.2 LMH under high-turbidity water conditions (300–1200 NTU), and simple forward flushing combined with sludge discharge can quickly restore ΔP. Overall, the variable load GDM system effectively manages membrane fouling and maintains stable filtration performance through the combined effects of variable load and intermittent operation, ensuring long-term and low-maintenance operation for decentralized water supply.

Stress-Induced Martensitic Transformation in Na3YCl6.

Martensitic transformation with volume expansion plays a crucial role in enhancing the mechanical properties of steel and partially stabilized zirconia. We believe that a similar concept could be applied to unexplored nonoxide materials. Herein, we report the stress-induced martensitic transformation of monoclinic Na3YCl6 with an ∼3.4% expansion. In situ synchrotron X-ray diffraction and atomistic simulations showed that anisotropic crystallographic transformation from monoclinic to rhombohedral Na3YCl6 occurs exclusively under uniaxial pressure; no effect is observed under hydrostatic pressure conditions. The uniaxially pressed powder compact of monoclinic Na3YCl6 showed a large indentation impression and low Young's modulus, in contrast to its high bulk modulus, suggesting that these unique mechanical properties are induced by the martensitic transformation.

Transcriptomic responses and evolutionary insights of deep-sea and shallow-water mussels under high hydrostatic pressure condition

Marine mussels inhabit a wide range of ocean depths, necessitating unique adaptations to cope with varying hydrostatic pressures. This study investigates the transcriptomic responses and evolutionary adaptations of the deep-sea mussel Gigantidas platifrons and the shallow-water mussel Mytilus galloprovincialis to high hydrostatic pressure (HHP) conditions. By exposing atmospheric pressure (AP) acclimated G. platifrons and M. galloprovincialis to HHP, we aim to simulate extreme environmental challenges and assess their adaptive mechanisms. Through comparative transcriptomic analysis, we identified both conserved and species-specific mechanisms of adaptation, with a notable change in gene expression associated with immune system, substance transport, protein ubiquitination, apoptosis, lipid metabolism and antioxidant processes in both species. G. platifrons demonstrated an augmented lipid metabolism, whereas M. galloprovincialis exhibited a dampened immune function. Additionally, the expressed pattern of deep-sea mussel G. platifrons were more consistent than shallow-water mussel M. galloprovincialis under hydrostatic pressures changed conditions which corresponding the long-term living stable deep-sea environment. Moreover, evolutionary analysis pinpointed positively selected genes in G. platifrons that are linked to transmembrane transporters, DNA repair and replication, apoptosis, ubiquitination which are important to cell structural integrity, substances transport, and cellular growth regulation. This indicates a specialized adaptation strategy in G. platifrons to cope with the persistent HHP conditions of the deep sea. These results offer significant insights into the molecular underpinnings of mussel adaptation to varied hydrostatic conditions and enhance our comprehension of the evolutionary forces driving their depth-specific adaptations.

Pressure-induced optical anisotropy of HfS2

The effect of pressure on Raman scattering (RS) in bulk HfS2 is investigated under hydrostatic and non-hydrostatic pressure conditions. The RS line shape does not change significantly in the hydrostatic regime up to P = 9.6 GPa, showing a systematic blueshift of the spectral features. In a non-hydrostatic environment, seven peaks appear in the spectrum at P = 7 GPa, which dominate the RS line shape up to P = 10.5 GPa. The change in the RS line shape manifests a pressure-induced phase transition in HfS2. The simultaneous observation of both low-pressure (LP) and high-pressure (HP) related RS peaks suggests the coexistence of two different phases over a wide pressure range. It is found that the HP-related phase is metastable and persists during the decompression cycle down to P = 1.2 GPa, while the LP-related features eventually recover at even lower pressure. The angle-resolved polarized RS performed under P = 7.4 GPa revealed a strong in-plane anisotropy of both the LP-related A1g mode and the HP peaks. The anisotropy is related to the possible distortion of the structure induced by the non-hydrostatic component of the pressure. The results are explained in terms of a distorted Pnma phase as a possible pressure-induced phase of HfS2.

Optoelectronic properties of mechanically stable cubic Niobate compounds under hydrostatic pressure: A systematic DFT investigation

Perovskite oxides, particularly cubic Niobate compounds, have been studied for their potential application in the development of optoelectronic devices. The mechanical stability of these compounds has been verified by determining their elastic constants. Based on an analysis of their electronic band structures and densities of states, it has been found that both compounds exhibit non-magnetic behavior and possess properties typical of indirect bandgap semiconductors. The bandgap energies of the compounds are 1.524 eV and 1.392 eV, respectively. The optical properties of the compounds are analyzed under varying hydrostatic pressure conditions. Bandgap modulation results in a shift in absorption spectra from ultraviolet to visible wavelengths, rendering the materials appropriate for use in optoelectronic devices. Perovskites with (K,Rb)NbO3 exhibit potential as non-magnetic indirect bandgap semiconductors for the advancement of optoelectronic devices.

Raman Spectroscopy on Free-Base Meso-tetra(4-pyridyl) Porphyrin under Conditions of Low Temperature and High Hydrostatic Pressure

We present a Raman spectroscopy study of the vibrational properties of free-base meso-tetra(4-pyridyl) porphyrin polycrystals under various temperature and hydrostatic pressure conditions. The combination of experimental results and Density Functional Theory (DFT) calculations allows us to assign most of the observed Raman bands. The modifications in the Raman spectra when excited with 488 nm and 532 nm laser lights indicate that a resonance effect in the Qy band is taking place. The pressure-dependent results show that the resonance conditions change with increasing pressure, probably due to the shift of the electronic transitions. The temperature-dependent results show that the relative intensities of the Raman modes change at low temperatures, while no frequency shifts are observed. The experimental and theoretical analysis presented here suggest that these molecules are well represented by the C2v point symmetry group.

Improving efficiency of vapour phase soldering ovens with pressure and temperature-based process monitoring

During vapour phase reflow soldering used in electronics manufacturing, the process control of ovens is usually based on temperature measurements, which can be insufficient due to the saturation differences in the temperature and the vapour concentration. Therefore, the ovens use extended cycle times for process identification to ensure the proper formation of solder joints. This study offers a solution to eliminate the idle time by investigating the hydrostatic pressure conditions in the process zone. A pressure measurement system was developed for vapour phase soldering ovens which can monitor the vapour pressure changes by a gauge-type pressure sensor with fused temperature measurement. It works as an IoT-enabled node for data logging and subsequent control. The fusion of the hydrostatic pressure values with the temperature values allowed us to identify and reduce the idle time by approximately 60 s, which is 15–20% of the total soldering cycle time. This increases the oven's yield by 15–20%, reduces the system's power consumption by 15–20%, and reduces time above liquidus of the solder by ∼35%. The presented method could enhance the more sustainable electronics production according to the Sustainability Development and could improve the quality and reliability of the lead-free solder joints.

Enzymatic fermentation of Uruka under hydrostatic pressure conditions

Uruka is a traditional Shiokara food made from the fermented viscera of ayu (sweetfish), which has high salinity. A common recipe involves anaerobic fermentation of salted ayu viscera densely packed in a container and capped during fermentation for several months or years under cool and ambient conditions. As the mechanism of Uruka fermentation remains unclear, we examined the microbiota of Uruka using 16S rRNA gene amplicon sequencing. As we were unable to identify the predominant microbes involved in Uruka fermentation, hydrostatic pressure conditions were applied to determine whether Uruka was fermented enzymatically or microbially. The results indicated that the fermentation of Uruka was enzymatic rather than microbial.

Underwater implosion behavior of 3D-printed polymer structures

This study experimentally investigates the failure behavior of 3D-printed polymer tubes during underwater implosion. Implosion is a prevalent failure mechanism in the underwater domain, and the adaptation of new technology, such as 3D printing, allows for the rapid manufacturing of pressure vessels with complex geometries. This study analyzes the failure performance of 3D-printed polymer structures to aid the future development of 3D-printed pressure vessels. The 3D-printed tube specimens analyzed were fabricated using digital light synthesis (DLS) technology and included four different case geometries. The geometries consist of three cylindrical shells of varying diameter and thickness and one double hull structure with a cylindrical gyroid core filler. These specimens were submerged in a pressure vessel and subjected to increasing hydrostatic pressure until implosion failure occurred. High-speed photography and Digital Image Correlation (DIC) were employed to capture the collapse event to obtain full-field displacements. Local dynamic pressure histories during failure were recorded using piezoelectric transducers. The findings highlight that the 3D-printed polymers underwent significant deformation and failed at localized points due to material failure. The fracture of the specimens during failure introduced inconsistencies in pressure and impulse data due to the chaotic nature of the failure. Notably, the energy flow analysis revealed that the proportion of energy released via the pressure pulse was lower than in traditional aluminum structures. These findings contribute to our understanding of the behavior of 3D-printed polymers under hydrostatic pressure conditions.

Investigation of high-pressure effect on the physical properties of FrNBr3 (N[dbnd]Ca, Sr) non-toxic halide perovskites

Utilizing ab-initio modeling, this study analyzes the possibility of replacing Lead with Francium halide perovskite for use in potential photovoltaic or optoelectronic device applications. Density functional theory is employed to estimate the structural, electronic, bonding, optical, anisotropic elastic, and mechanical characteristics of FrNBr3 (NCa, Sr) at various hydrostatic stresses scaling from 0 to 80 GPa. The calculation of the tolerance factor validates the structural stability. At 0 GPa pressure, the computed lattice constants for FrCaBr3 and FrSrBr3 are 5.78 Å (5.38 Å) and 6.03 Å (5.62 Å), respectively, using GGA (HSE03) approximation potential. FrNBr3 (NCa, Sr) perovskites show increased band gap values using the HSE03 method. Notably, these HSE03-derived values align with the trends observed in the GGA-PBE scheme, under both normal and hydrostatic pressure conditions. As pressure increases, both the lattice constant and unit cell volume decrease significantly. The estimated direct band gaps demonstrate the semiconducting nature of the compounds under ambient pressure. However, when pressure increases, the band gap narrows, increasing conductivity, and makes it as one of the great contenders of microelectronics as well as tandem photovoltaics due to its shift from ultraviolet to visible light energy region. Applying pressure enhances the optical properties, showcasing its utility in various semiconductor applications within the visible ranges and overcoming its limited usage in the ultraviolet domain. In the same vein, the application of hydrostatic pressure significantly impacts mechanical properties without compromising stability. The ductile and anisotropy character become more pronounced when pressure is exerted.

Investigation of the interface stick-slip friction behavior of clay nanoplatelets by molecular dynamics simulations

As lamella and porous materials, the failure of clay soil is closely related to the microscale friction features between nano minerals sheets. This study delves into the microscale interface stick-slip friction behavior of clay minerals, with a particular focus on kaolinite and halloysite models, under varying hydrostatic pressure conditions. The research unveils several significant discoveries. Firstly, under hydrostatic pressure, the mechanical properties of clay minerals perpendicular to the mineral platelet weaken, accompanied by a gradual reduction in the space occupied by interlayer water molecules. As pressure increases, these molecules assemble into "water molecular clusters", resulting in the formation of two or three layers of water molecular films. At 6 GPa, interlayer water nearly reaches a state of stagnation. Secondly, both kaolinite and halloysite exhibit "stick-slip friction behavior" during shearing, with rising hydrostatic pressure intensifying interatomic interactions and augmenting shear stress fluctuations. Lastly, the calculated friction coefficients (μ) for the three systems (kaolinite –7 Å, halloysite –8.6 Å, and halloysite –10 Å) are 0.035, 0.048, and 0.033, respectively, while the friction angles (φ) are 2.270, 2.900, and 2.263. The cohesion values (C) for these systems, obtained through different methods, demonstrate consistency. These findings advance the understanding of clay mineral behavior under varying conditions and contribute valuable insights to the microscale failure mechanism of clay soil.

Underwater sound-absorbing performance of composite structure under hydrostatic pressure by considering constitutive models

Underwater vessels face significant challenges as the high hydrostatic pressure of deep water affects their stealth performance. Linear models may not accurately depict the deformation of structures under hydrostatic pressure due to its non-linear properties of rubber and therefore, influence the results. This study utilized uniaxial tension and compression test data of styrene-butadiene rubber to fit four constitutive models and the optimal was selected to calculate the sound-absorbing performance under hydrostatic pressures,. Results showed that the Yeoh model fitted by uniaxial compression with r2 of 0.9928. Viscous losing, waveform conversion and locally resonance are main sound-absorbing mechanisms. The maximum sound-absorbing coefficient of structure at 0 MPa is 0.8914 at 7.6 kHz and the sound-absorbing performance mostly decreases with increasing hydrostatic pressure, Maximum reduction of 32 % was achieved at 3.2 kHz. Experiments verified the accuracy of simulation results, and the mean relative errors between the simulated results and the experimental results are 15.28 % (0 MPa), 16.91(0.5 MPa) %, 16.67 % (1 MPa) and 16.38 % (2 MPa), respectively. These findings can provide guidance for development of underwater sound-absorbing structures in hydrostatic pressure conditions.

Cultivation and biogeochemical analyses reveal insights into biomineralization caused by piezotolerant iron-reducing bacteria from petroleum reservoirs and their application in MEOR

Interactions between minerals and iron-reducing bacteria under in-situ pressure and temperature conditions play important roles in oil extraction, residual oil methanation, and CO2 storage in petroleum reservoirs. However, the impacts of pressure on dissimilatory iron-reducing bacteria (DIRB) are poorly understood. Herein, the interactions between clay minerals and microbes under elevated hydrostatic pressure conditions were elucidated through enrichment experiments. Bioreduction experiments were performed under hydrostatic pressures of 0.1–40 MPa. Microbial diversity analysis revealed that high pressures significantly increased microbial diversity in petroleum reservoirs, which is helpful for restoring underground ecosystems in situ. The key piezotolerant iron-reducing bacteria in the samples were Shewanella and Flaviflexus. These two genera were isolated for the first time from petroleum reservoirs and identified as piezophiles. The SEM results clearly showed mineral surface dissolution. Moreover, nanoscale secondary minerals were produced during biomineralization. XRD analysis revealed that illite, albite, and clinoptilolite were present after bioreduction. The isolates showed the capacity to inhibit hydro-swelling and prevent plugging-related damage in reservoirs.

Investigations on the Stinger PDC cutter breaking granitoid under in-situ stress and hydrostatic pressure conditions

Investigations on the Stinger PDC cutter breaking granitoid under in-situ stress and hydrostatic pressure conditions

Shear-induced phenotypic transformation of microglia in vitro

The brain cells are affected by continuous fluid shear stress that is driven by varying hydrostatic and osmotic pressure conditions, depending on the brain’s pathophysiological conditions. Although all brain cells are sensitive to the subtle changes in various physicochemical factors in the microenvironment, microglia, the resident brain immune cells, exhibit the most significant morphodynamic transformation. However, little is known about the phenotypic alterations in microglia in response to changes in fluid shear stress. In this study, we established a flow-controlled microenvironment to investigate the effects of shear flow on microglial phenotypes, including morphology, motility, and activation states. We observed two distinct morphologies of microglia in a static condition: bipolar cells that oscillate along their long axis and unipolar cells that migrate persistently. When exposed to flow, a significant fraction of bipolar cells showed unstable oscillation with an increased amplitude of oscillation and a decreased frequency, which consequently led to the phenotypic transformation of oscillating cells into migrating cells. Furthermore, we observed that the level of proinflammatory genes increased in response to shear stress, although there were no significant changes in the level of antiinflammatory genes. Our findings suggest that an interstitial fluid-level stimulus can cause a dramatic phenotypic shift in microglia toward proinflammatory states, shedding light on the pathological outbreaks of severe brain diseases. Given that the fluidic environment in the brain can be locally disrupted in pathological circumstances, the mechanical stimulus by fluid flow should also be considered a crucial element in regulating the immune activities of the microglia in brain diseases.

TRIM Simulations Tool for µ + Stopping Fraction in Hydrostatic Pressure Cells

For quantum systems or materials, a common procedure for probing their behaviour is to tune electronic/magnetic properties using external parameters, e.g. temperature, magnetic field or pressure. Pressure application as an external stimuli is a widely used tool, where the sample in question is inserted into a pressure cell providing a hydrostatic pressure condition. Such device causes some practical problems when using in Muon Spin Rotation/Relaxation (µ +SR) experiments as a large proportion of the muons will be implanted in the pressure cell rather than in the sample, resulting in a higher background signal. This issue gets further amplified when the temperature dependent response from the sample is much smaller than that of the pressure cell,which may cause the sample response to be lost in the background and cause difficulties in aligning the sample within the beam. To tackle this issue, we have used pySRIM [1] to construct a practical and helpful simulation tool for calculating muon stopping fractions, specifically for the pressure cell setup at the µE1 beamline using the GPD spectrometer at the Paul Scherrer Institute, with the use of TRIM simulations. The program is used to estimate the number of muon stopping in both the sample and the pressure cell at a given momentum. The simultion tool is programmed into a GUI, making it accessible to user to approximate prior to their experiments at GPD what fractions will belong to the sample and the pressure cell in their fitting procedure.

A new fabrication method of designed metamaterial based on a 3D-printed structure for underwater sound absorption applications

Effective sound absorption in a broad frequency range of thin-anechoic materials is a challenge that acoustic materials for underwater applications are still facing. This study proposes a thin-anechoic membrane for underwater applications with an innovative fabrication method for a designed metamaterial based on a 3D-printed structure with a cone-shaped cavities array. The structure is printed with thermoplastic polyurethane (TPU) and cast in a thermoset polyurethane (SPU). Three types of TPUs with different hardness were used to assess the contribution of the polymer properties to the sound absorption performance in the frequency range from 1.5 kHz to 7 kHz and hydrostatic pressure conditions from normal pressure to 1.5 MPa. The materials were characterised using FTIR, FESEM, tensile and compression testing. The FTIR results evidenced a shift of the peak absorption from 1727 cm−1 to 1701 cm−1 when the hardness of the TPU is increased, suggesting a more reinforced network structure that enhances the mechanical properties. The SEM images provided an understanding of the matrix condition given by the 3D-printing parameters, evidencing cavity characteristics that affect the filament adhesion and the mechanical response. Compression testing evidenced the strain-value change of the materials under compression stress and consequently its stability under hydrostatic pressure from 0 MPa to 1.5 MPa. The metamaterial with the designed structure shows a significant improvement in the sound absorption coefficient and more stable coefficient values under hydrostatic pressure when the 82-TPU was used in the 3D-printed structure.

Cultivation of Piezotolerant and Piezophilic Hyperthermophiles with a Newly Developed Constant High Pressure and Temperature Culturing and Monitoring System.

The Earth's microbial biosphere extends from ambient to extreme environments, including deep-sea hydrothermal vents and subseafloor habitats. Despite efforts to understand the physiological adaptations of these microbes, our knowledge is limited due to the technological challenges associated with reproducing in situ high temperature (HT)-high hydrostatic pressure (HHP) conditions and sampling HT-HHP cultures. In the present study, we developed a new high temperature and pressure (HTP) incubation system that enabled the maintenance of HT-HHP conditions while sampling incubation medium and mostly eliminated non-biological reactions, including hydrogen generation or the leakage of small gaseous molecules. The main characteristics of our system are (1) a chamber made of gold with gold-etched lid parts that suppress the majority of non-biological reactions, (2) the exceptional containment of dissolved gas, even small molecules, such as hydrogen, and (3) the sampling capacity of intra-chamber liquid without depressurization and the isobaric transfer of a culture to inoculate new medium. We initially confirmed the retention of dissolved hydrogen in the incubation container at 82°C and 20‍ ‍MPa for 9 days. Cultivation tests with an obligate hyperthermophilic piezophile (Pyrococcus yayanosii), hydrogenotrophic hyperthermophile (Archaeoglobus profundus), and heterotrophic hyperthermophile (Pyrococcus horikoshii) were successful based on growth monitoring and chemical ana-lyses. During HTP cultivation, we observed a difference in the duration of the lag phase of P. horikoshii, which indicated the potential effect of a pressure change on the physiology of piezophiles. The present results suggest the importance of a cultivation system designed and developed explicitly for HTP conditions with the capacity for sampling without depressurization of the entire system.

Underwater soil sounding at the site of burial

Technical means of engineering-geological research at the site of occurrence are the most complex and expensive equipment, requiring special equipment for their operation in conditions of high hydrostatic pressure and aggressive environment, the corresponding program of the movement of the escort vessel, remote control of research devices, transmission and registration of received data. The complex of methods and means for measuring the physical and mechanical properties of bottom soils in natural occurrence includes stamp tests of soils; measurement of resistance to rotational shear with an impeller; penetration logging; static and dynamic sounding; long-term studies with bottom installations; radiometric methods of testing soils; measurement of physical characteristics of soils; bottom exploration by gliding submersibles. This article discusses devices and methods for point testing of underwater soil in situ by static, dynamic and gravity sounding.

Drilling of deep and ultra-deep wells for prospecting and exploration of new raw mineral fields

Scientific and technological progress over the last century has led to an enormous increase in the consumption of minerals, including energy resources. Most of the exploited oil and gas fields are already considerably depleted, so it is necessary to search for new hydrocarbon resources, particularly at great depths. Deep drilling plays a special role in solving this problem. The article considers the world and Russian experience of ultra-deep wells drilling. The me-thods and technologies used in the construction of wells, as well as complications and accidents occurring during their drilling were analyzed. The analysis revealed that the existing limitations for drilling parameters of deep and ultra-deep wells are caused by the technical characteristics of surface and bottomhole drilling equipment, which do not meet the extreme drilling conditions. The directions for development of deep and ultra-deep well drilling machinery and technologies are suggested. The notion of extreme rock and geological drilling conditions is introduced, which describes drilling in conditions of hydrostatic pressure of flushing fluid column and high bottomhole temperature both at stable and unstable wellbore conditions, coming close to the upper limit of operating technical characteristics of bottomhole assembly, the drill string and flushing fluid.