High Fluid Pressure Research Articles

Non-invasive estimation of cerebrospinal fluid pressure in idiopathic intracranial hypertension: magnetic resonance imaging analysis of optic nerve and eyeball.

Invasive methods such as lumbar puncture and intraventricular catheters are commonly used to measure intracranial pressure (ICP). This study aims to develop quantitative and non-invasive techniques to measure ICP in patients with Idiopathic Intracranial Hypertension (IIH) using magnetic resonance imaging (MRI) findings. MRI data obtained from 50 patients with IIH and 30 age- and sex- matched controls were analyzed and optic nerve sheath diameter (ONSD), eyeball transverse diameter (ETD) and optic nerve diameter (OND) were measured. ONSD, ONSD/ETD and OND/ONSD indexes were calculated according to different ONSD measurement distances. Correlations of MRI findings with ICP were calculated. Sensitivity and specificity of all methods were analyzed. ONSD and ONSD/ETD index at 3mm and 10mm behind the eyeball were significantly higher (p < 0.001) and OND/ONSD index at 3mm behind the eyeball was significantly lower (p < 0.001) in the IIH group. The ONSD/ETD index at 3mm had the highest area under the curve (AUC) value (0.898) with a cut-off of 0.27mm (82% sensitivity and 91.67% specificity) for predicting high cerebrospinal fluid (CSF) pressure, followed by ONSD measurements at 3mm (AUC = 0.886) with a cut-off of 6.17mm (83% sensitivity and 86.67% specificity). The OND/ONSD index at 3mm posterior to the eyeball decreased significantly as ICP increased, and the strength of the relationship was moderate (p < 0.001; r = -0.358). ONSD and ONSD/ETD index measured on MRI sequences are potentially useful in detecting elevated ICP. The OND/ONSD index correlates with CSF pressure and these techniques may be helpful in diagnosing IIH.

Coordinate system setting for post-machining of impeller shape by wire arc DED and evaluation of processing efficiency

Wire arc additive manufacturing (WAAM) is a direct energy deposition (DED) process that uses arc welding. It is a method of stacking beads made by melting metal wires with an arc heat source generated by a short-circuit current. Compared to other metal additive manufacturing methods, this process can be used to quickly produce large and complex-shaped metal parts. However, due to the multi-bead stacking method, the surface is highly curved and the dimensional errors are large; therefore, post-processing of the surface by cutting is required. Impellers, which are widely used in various industries, have complex shapes and high material consumption during cutting; therefore, the WAAM process can improve the manufacturing efficiency. In this study, a manufacturing process for an impeller with a diameter of 160 mm was developed by using the WAAM process. A 6-bladed fan-type impeller used for high-pressure fluid delivery was similarly modeled, and the product was additively manufactured using an Inconel 625 alloy wire. Manufacturing conditions that ensure productivity and quality or the product were determined through experimentation. Considering the post-processing of the WAAM-fabricated structure, the robot and tool paths of the impeller model were designed, and the error in the process coordinate system caused by attaching and detaching the workpiece between the two processes was reduced. Through the post-processing of the WAAM-fabricated structure, the production efficiency and process reliability were verified when the conventional manufacturing method and WAAM process were applied.

Comprehensive analysis of the effect of structural parameters on erosion wear, structural stress, and deformation of high-pressure double-elbow in shale-gas fracturing

In field hydraulic fracturing operation of shale gas development, the high pressure and large displacement liquid-particle two-phase fracturing fluid can be forced to change direction many times through high-pressure double-elbow, and be transported from the outlet pipeline of the fracturing pump to the main pipeline. The high-pressure double-elbow is prone to be affected by erosion wear and Fluid-Structure Interaction (FSI), resulting in perforation and fracture, posing a potential safety threat to field operation. In this study, we conducted the erosion wear experiments on 35CrMo steel used for high-pressure double-elbow in shale-gas fracturing. The erosion rates under different impact angles and flow velocities were obtained, and proposed a novel model of erosion prediction for high-pressure double-elbow. Then the numerical investigation was employed to conduct a comprehensive analysis of erosion wear, structural stress and deformation by the coupling of Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA). The effects of structural parameters such as connection straight pipe length, pipe inner diameter and fluid turning direction were discussed. The results indicate that with the increase of connection straight pipe length, the flow erosion decreases first then varies little, and the deformation gradually increases. Slight erosion wear but large structural stress and deformation in major inner diameter pipe. And the minimum degree of erosion and flow-induced deformation present with the fluid turning direction of double-elbow as 0°. The study can provide references for the design, installation and detection of high-pressure double-elbow and ensure safety in the process of shale gas fracturing.

Bubble behavior of single-pulse discharge in EDM

The removal of machining debris in the narrow discharge gap primarily relies on high pressure bubble expansion and fluid agitation induced by the bubble pulsation in electrical discharge machining (EDM). Observing bubble behavior and elucidating the mechanism of bubble behavior is an increasing concern in EDM. The purpose of this study is to investigate the bubble behavior of single pulse discharge in EDM. Using a high-speed camera, this study observed the bubble evolution and measured the discharge duration dependent bubble characteristics. The results show that the bubble experiences rapid expansion, contraction, primary pulsation, intense pulsation in the post-discharge process, and subsequent bubble energy dissipation behavior. Furthermore, the arc plasma persists for a duration even after the discharge ends in positive polarity machining. The findings suggest that bubble behavior in single-pulse discharges is primarily dominated by the discharge energy, with the bubble behavior during the discharge significantly influenced by the jumping and oscillation of the arc plasma. Our research may introduce new ideas for improving the depth-to-diameter ratio of deep micro-holes in EDM and provide fresh perspectives on the mechanism analysis of how machining parameters affect machining performance. For instance, by synchronizing the pulse intervals with the bubble stabilization time, bubble coalescence can be reduced, thus increasing bubble removal in the small machining gap. The stability of deep micro-hole EDM may depend on bubble behavior, which is determined by the electrical parameters.

Localization of Deformation on Faults Driven by Fluids During the L’Aquila 2009 Earthquake

AbstractCoseismic rupture and aftershock development on a fault plane are complex and heterogeneous processes. The Mw 6.1 L’Aquila 2009 normal faulting earthquake is a perfect case to explore how fault geometry and rheology influence the rupture process and aftershocks distribution. In this study, we use for the first time a dense set of earthquake data to obtain enhanced images of the causative normal fault structure to the kilometer scale. The hypocenter of the emergent onset of the mainshock took place within a low Vp/Vs volume, while the large coseismic slip occurred a few kilometers above, as the rupture propagated through a high Vp and high Vp/Vs fluid‐filled rock volume. The increase of Vp/Vs in the fault hanging wall during the sequence suggests a strong dehydration in the earthquake asperity, with an upward fluid pressure migration along the fault toward the host rock volume. We propose that the localization of deformation on the fault plane is favored by high fluid pressure, while the spreading of aftershocks on a wide volume around the fault is driven by the depletion of fluids from the slipped portion of the fault plane and migration to small segments within the fault host rocks.

Synthesis of chitosan polyethylene glycol antibody complex for delivery of Imatinib in lung cancer cell lines.

Lung cancer is known as the most common cancer. Although the Ramucirumab antibody is a second-line treatment for lung cancer, the high interstitial fluid pressure limits the antibody's performance. In this way, Imatinib is a chemotherapeutic drug to reduce the interstitial fluid pressure. Up to now, unfortunately, both Ramucirumab and imatinib have not been reported in one nanosystem for cancer therapy. To fulfill this shortcoming, this paper aims to design a chitosan nanocarrier that loads imatinib and attaches to Ramucirumab for selective bonding to A549. Therefore, this paper aims to develop a polymeric nanosystem for non-small cell lung cancer (NSCLC) treatment. In first, the chitosan polyethylene glycol nanoparticle is synthesized, loaded with imatinib, and then targeted using Ramucirumab. Afterwards, the CS-PEG-Ab-Im by FTIR, TEM, DLS, zeta potential, and TGA techniques are characterized. The size of CS-PEG-Ab-Im was 25-30 nm, its surface charge was 13.1 mV, and the shape of CS-PEG-Ab-Im was nearly spherical and cylindrical. The therapeutic potential of CS-PEG-Ab-Im was assessed using the A549 cell line. According to the obtained results, the cell viability was 48% after 48 h of treatment of A549 cells using the IC50 concentration of CS-PEG-Ab-Im (100 nanomolar). Moreover, the apoptosis and cell cycle arrest percentages were increased by 3 and 6 times, respectively, as compared to free imatinib. Furthermore, the release rate of imatinib from CS-PEG-Ab-Im in an acidic medium was 17% during 1 h, indicating five times the imatinib release in the natural medium. Eventually, the result of flow cytometry indicates the more apoptotic effect of nanosystem to free imatinib and CS-PEG-Ab. Besides, cell arresting result exhibits the CS-PEG-Ab-Im and causes cell arrested at G1 by %8.17. Thus, it can be concluded that CS-PEG-Ab-Im can be an ideal nanosystem in NSCLC treatment.

AN OVERVIEW ON SHEET METAL HYDROFORMING TECHNOLOGIES

The hydroforming process is a nonconventional method for producing sheet metal deep drawing pieces, under the direct or indirect action of a high pressure fluid on the inner or outer side of work piece wall. This process it`s known since the 1900s and it has continuously developed, being today a field of research in the universities from country and abroad. The design of the hydroforming process can be done according to empirical, analytical and numerical methods to obtain high precision of the hydroforming piece and to ensure a large deformation of the material. The hydroforming parts can be used in various fields such as the automotive, aircraft and aerospace industries, having relatively low costs compared to parts obtained by other types of processing such as rolling, forging or stamping. The paper gives an overview regarding the sheet metal hydroforming processes, methods and the equipment used, as well as the process limits and defects that can occur during hydroforming.

Amelioration of breast cancer therapies through normalization of tumor vessels and microenvironment: paradigm shift to improve drug perfusion and nanocarrier permeation.

Breast cancer (BC) is the most commonly diagnosed cancer among women. Chemo-, immune- and photothermal therapies are employed to manage BC. However, the tumor microenvironment (TME) prevents free drugs and nanocarriers (NCs) from entering the tumor premises. Formulation scientists rely on enhanced permeation and retention (EPR) to extravasate NCs in the TME. However, recent research has demonstrated the inconsistent nature of EPR among different patients and tumor types. In addition, angiogenesis, high intra-tumor fluid pressure, desmoplasia, and high cell and extracellular matrix density resist the accumulation of NCs in the TME. In this review, we discuss TME normalization as an approach to improve the penetration of drugs and NCSs in the tumor premises. Strategies such as normalization of tumor vessels, reversal of hypoxia, alleviation of high intra-tumor pressure, and infiltration of lymphocytes for the reversal of therapy failure have been discussed in this manuscript. Strategies to promote the infiltration of anticancer immune cells in the TME after vascular normalization have been discussed. Studies strategizing time points to administer TME-normalizing agents are highlighted. Mechanistic pathways controlling the angiogenesis and normalization processes are discussed along with the studies. This review will provide greater tumor-targeting insights to the formulation scientists.

A laboratory perspective on accelerating preparatory processes before earthquakes and implications for foreshock detectability

Dynamic failure in the laboratory is commonly preceded by many foreshocks which accompany premonitory aseismic slip. Aseismic slip is also thought to govern earthquake nucleation in nature, yet, foreshocks are rare. Here, we examine how heterogeneity due to different roughness, damage and pore pressures affects premonitory slip and acoustic emission characteristics. High fluid pressures increase stiffness and reduce heterogeneity which promotes more rapid slip acceleration and shorter precursory periods, similar to the effect of low geometric heterogeneity on smooth faults. The associated acoustic emission activity in low-heterogeneity samples becomes increasingly dominated by earthquake-like double-couple focal mechanisms. The similarity of fluid pressure increase and roughness reduction suggests that increased stress and geometric homogeneity may substantially shorten the duration of foreshock activity. Gradual fault activation and extended foreshock activity is more likely observable on immature faults at shallow depth.

Comprehensive corrosion failure analysis of HAl77-2 alloy tubes serving in a low temperature multi-effect distillation plant: From feature analysis to corrosion mechanisms

Premature perforation and leakage of HAl77-2 alloy heat exchanger tubes occurs after 2.5 years of service in the largest low temperature multi-effect distillation (LT-MED) plant in China. The root reasons of perforation and leakage of tubes were investigated through macroscopic morphology, chemical composition, metallographic structure, seawater quality, flowing simulation and microstructure characterization. The results show that the HAl77-2 alloy tubes with perforation leakage meet the standard requirements. And the failure of the tubes was mainly attributed to the synergistic effect of serious pitting corrosion and stress cracking caused by the high fluid pressure and polluted seawater with Fe2+/Fe3+, sulfide and NH4+. Especially, the velocity and pressure spatial distribution of liquid film on the outside of horizontal tubes well verified the interesting observation that corrosion pits concentrating in one strip on the top of the tube. Moreover, corrosion mechanism was proposed that the loose corrosion products of Cu2S, FeS and Cu2(OH)3Cl lead to the formation of some defect points on the homogeneous protective Cu2O layer. For these defect points, the direct expose of the alloy matrix to corrosive substances such as Cl− and NH4+, significantly accelerates the dissolution of Cu in form of CuCl2− and Cu(NH3)2+ from the alloy. Finally, the tube occurs pitting corrosion and even perforates under the strong hydraulic erosion after long-terms of operation.

Empirical heat transfer correlations of high-pressure transcritical fluids at low Reynolds numbers

Empirical heat transfer correlations serve as indispensable tools for predicting and optimizing the thermal performance of a wide range of engineering devices, like for example in energy conversion and propulsion applications. Although a remarkable number of correlations exist for systems at low (atmospheric) pressures, accurately quantifying heat transfer under high-pressure transcritical conditions poses a notable challenge, especially at low Reynolds numbers due to the scarcity of correlations available in the literature. This difficulty has prompted the widespread use of general empirical correlations, which are inadequate for such flow conditions, and hold significant implications, for instance, in fields like microfluidics technology. In this regard, the aim of this study is to develop novel heat transfer correlations tailored for high-pressure transcritical fluids at relatively low Reynolds numbers. These correlations are derived from a dataset of 18 direct numerical simulations of carbon dioxide confined between differentially heated walls, which induce a transcritical trajectory through the pseudo-boiling region. The correlations are developed for both the cold liquid-like and hot gas-like regions, resulting in a total of 6 correlations that encompass the laminar, transitional, and turbulent flow regimes. In particular, as a function of Reynolds, Prandtl, Eckert and Mach numbers, the proposed empirical correlations provide accurate estimations with relative errors below 8%, which significantly surpass existing literature correlations.

Fatigue performance testing and life prediction of welded fuel pipes

The external piping system which connects power devices, valve control devices, actuators, etc. is an essential system on the aero engine. Under the combined effects of high fluid pressure and external vibration, multiaxial fatigue failure is the main factor that seriously affects the safety of the piping system. The objective of this paper is to establish the multiaxial fatigue life model for the typical welded fuel pipe of the piping system by combining fatigue testing, simulation and theoretical analysis which is of great guiding significance for the engineering application of the piping system. Firstly, the fatigue limits of welded fuel pipes under no and 13.5 MPa internal pressure are obtained by rotational bending fatigue tests using the up-and-down method. Three additional stress levels of rotational bending fatigue tests under no internal pressure are supplemented and then the S-N curve is further obtained by the group method. Since the corresponding fracture surface of the specimens locates at the weld toe near the fixed end, peak stress method is adopted to evaluate the fatigue performance of the weld toe on the pipe specimens. In addition, by comparing the fatigue limit with no and 13.5 MPa internal pressured pipes, it is obvious that the equivalent uniaxial stress corrected by Gerber formula is not applicable for the multiaxial fatigue condition which is caused by the combined effect of fluid pressure and displacement load. The local stress concentration factor caused by the weld toe is determined and based on Findley critical plane model, the multiaxial fatigue life model is established which simultaneously takes the local stress concentration effect, mean stress effect and multiaxial stress effect into consideration. The results of rotational bending fatigue tests under 13.5 MPa internal pressure are within the triple error dispersion band and the accuracy of the proposed life model are verified.

Regulation of IFP in solid tumours through acoustic pressure to enhance infiltration of nanoparticles of various sizes

Numerous nanomedicines have been developed recently that can accumulate selectively in tumours due to the enhanced permeability and retention (EPR) effect. However, the high interstitial fluid pressure (IFP) in solid tumours limits the targeted delivery of nanomedicines. We were previously able to relieve intra-tumoural IFP by low-frequency non-focused ultrasound (LFNFU) through ultrasonic targeted microbubble destruction (UTMD), improving the targeted delivery of FITC-dextran. However, the accumulation of nanoparticles of different sizes and the optimal acoustic pressure were not evaluated. In this study, we synthesised Cy5.5-conjugated mesoporous silica nanoparticles (Cy5.5-MSNs) of different sizes using a one-pot method. The Cy5.5-MSNs exhibited excellent stability and biosafety regardless of size. MCF7 tumour-bearing mice were subjected to UTMD over a range of acoustic pressures (0.5, 0.8, 1.5 and 2.0 MPa), and injected intravenously with Cy5.5-MSNs. Blood perfusion, tumour IFP and intra-tumoural accumulation of Cy5.5-MSNs were analysed. Blood perfusion and IFP initially rose, and then declined, as acoustic pressure intensified. Furthermore, UTMD significantly enhanced the accumulation of differentially sized Cy5.5-MSNs in tumour tissues compared to that of the control group, and the increase was sevenfold higher at an acoustic pressure of 1.5 MPa. Taken together, UTMD enhanced the infiltration and accumulation of Cy5.5-MSNs of different sizes in solid tumours by reducing intra-tumour IFP.

Numerical investigation of heat extraction performance affected by stimulated reservoir volume and permeability evolution in the enhanced geothermal system

The high-permeability stimulated reservoir volume (SRV) containing artificial fractures is the main region for deep geothermal extraction. Evaluating the SRV distribution and the contributions of fluid pressure and thermal stress to permeability evolution is essential to accurately quantify heat extraction. Here, we employ the numerically calculated pore pressure and the field-measured rock failure as evaluation indicators to reasonably identify the SRV and investigate the effect of rock and fracture permeability evolution on heat extraction performance. We find that simply assuming the entire model as the SRV would significantly overestimate the heat extraction, and scientifically defining the SRV based on hydraulic fracturing is crucial. The variable rock permeability model extracts marginally less heat as the working fluid squeezes and cools surrounding rocks causing their lower permeability. In regions around the injection well, both the high fluid pressure and the thermal stress increase the fracture aperture and permeability, whereas the fluid pressure shows the opposite effect around the production well as it is lower than the initial pore pressure. When the main fractures connect injection and production wells, the widened fractures accelerate fluid flow, causing higher heat extraction for a short time (first 4 years); however, after 4 years’ operation, the heat extraction remains at a lower value for a long time as the increased fracture permeability causes more fluids to flow directly from main fractures to the production well without playing participating in heat exchange. When the main fractures do not connect injection and production wells, the increased fracture permeability slightly enhances the heat extraction over the geothermal extraction process with a relative error less than 0.025. This study provides guidance for the appropriate selection of geothermal extraction simulation assumptions.

Mechanism and Model Analysis of Ultralow-Temperature Fluid Fracturing in Low-Permeability Reservoir: Insights from Liquid Nitrogen Fracturing

Ultralow-temperature fluids (such as liquid nitrogen, liquid CO2) are novel waterless fracturing technologies designed for dry, water-sensitive reservoirs. Due to their ultralow temperatures, high compression ratios, strong frost heaving forces, and low viscosities, they offer a solution for enhancing the fracturing and permeability of low-permeability reservoirs. In this study, we focus on the combined effects of high-pressure fluid rock breaking, low-temperature freeze-thaw fracturing, and liquid-gas phase transformation expansion on coal-rock in low-permeability reservoirs during liquid nitrogen fracturing (LNF). We systematically analyze the factors that limit the LNF effectiveness, and we discuss the pore fracture process induced by low-temperature fracturing in coal-rock and its impact on the permeability. Based on this analysis, we propose a model and flow for fracturing low-permeability reservoirs with low-temperature fluids. The analysis suggests that the Leidenfrost effect and phase change after ultralow-temperature fluids enter the coal support the theoretical feasibility of high-pressure fluid rock breaking. The thermal impact and temperature exchange rate between the fluid and coal determine the temperature difference gradient, which directly affects the mismatch deformation and fracture development scale of different coal-rock structures. The low-temperature phase change coupling fracturing of ultralow-temperature fluids is the key to the formation of reservoir fracture networks. The coal-rock components, natural fissures, temperature difference gradients, and number of cycles are the key factors in low-temperature fracturing. In contrast to those in conventional hydraulic fracturing, the propagation and interaction of fractures under low-temperature conditions involve multifield coupling and synergistic temperature, fluid flow, fracture development, and stress distribution processes. The key factors determining the feasibility of the large-scale application of ultralow-temperature fluid fracturing in the future are the reconstruction of fracture networks and the enhancement of the permeability response in low-permeability reservoirs. Based on these considerations, we propose a model and process for LNF in low-permeability reservoirs. The research findings presented herein provide theoretical insights and practical guidance for understanding waterless fracturing mechanisms in deep reservoirs.

Magnetic resonance imaging of tumor response to stroma-modifying pegvorhyaluronidase alpha (PEGPH20) therapy in early-phase clinical trials

Pre-clinical and clinical studies have shown that PEGPH20 depletes intratumoral hyaluronic acid (HA), which is linked to high interstitial fluid pressures and poor distribution of chemotherapies. 29 patients with metastatic advanced solid tumors received quantitative magnetic resonance imaging (qMRI) in 3 prospective clinical trials of PEGPH20: HALO-109-101 (NCT00834704), HALO-109-102 (NCT01170897), and HALO-109-201 (NCT01453153). Apparent Diffusion Coefficient of water (ADC), T1, ktrans, vp, ve, and iAUC maps were computed from qMRI acquired at baseline and ≥ 1 time point post-PEGPH20. Tumor ADC and T1 decreased, while iAUC, ktrans, vp, and ve increased, on day 1 post-PEGPH20 relative to baseline values. This is consistent with HA depletion leading to a decrease in tumor extracellular water content and an increase in perfusion, permeability, extracellular matrix space, and vascularity. Baseline parameter values predictive of pharmacodynamic responses were: ADC > 1.46 × 10−3 mm2/s (Balanced Accuracy (BA) = 72%, p < 0.01), T1 > 0.54 s (BA = 82%, p < 0.01), iAUC < 9.2 mM-s (BA = 76%, p < 0.05), ktrans < 0.07 min−1 (BA = 72%, p = 0.2), ve < 0.17 (BA = 68%, p < 0.01), and vp < 0.02 (BA = 60%, p < 0.01). A low ve at baseline was moderately predictive of response in any parameter (BA = 65.6%, p < 0.01 averaged across patients). These qMRI biomarkers are potentially useful for guiding patient pre-selection and post-treatment follow-up in future clinical studies of PEGPH20 and other tumor stroma-modifying anti-cancer therapies.

Statistical analysis of rotary atomization by phase Doppler anemometry

Rotary atomization is used in a wide variety of fields, exploiting the external control option of the spray while no high-pressure fluid is needed. Most papers on rotary atomization deal with liquid jet breakup, while external spray characteristics are rarely evaluated; this is performed currently. The water spray was measured by a two-component phase Doppler anemometer. The optical setup requires a special measurement chamber to avoid spray deposition on the optical components. Therefore, the first goal was to find a proper filter that enables the removal of biased droplets by secondary flows. Since most droplets have a similar radial-to-tangential velocity ratio at each measurement point, i.e., scattering around a line, this was the first component of the best filter. The second component was the need for a positive radial velocity component. This filter efficiently removed droplets originating from alternative processes, increasing the R2 of the line fit. The physical soundness of this filter was checked by evaluating the effect of filtering on the angle of the velocity components of each droplet at a given measurement point. The proposed filter efficiently detected recirculation, a secondary effect of the measurement setup with less regular dataset shapes. Finally, the slope and intercept values of the fitted lines were evaluated and presented. The mean of the former followed the same trend irrespective of the rotational speed and the mass flow rate; it was principally dependent on the radial distance from the atomizer. The intercept showed a regular but less universal behavior.

Multiple sulfur isotopes evidence deep intra-slab transport of sulfate-rich fluids

Sub-arc mantle oxidation is often attributed to sulfates from seawater transported in aqueous fluids derived from slab dehydration, but sulfur speciation and origin(s) in high-pressure fluids remain weakly constrained. Here, we use the four sulfur stable isotopes (32S, 33S, 34S, 36S) to decipher processes, e.g. mixing of two end-member reservoirs and open-system reaction occurring during sulfur devolatilization, and deduce the nature and origin of sulfur species in aqueous slab-derived fluids. We analyzed high pressure metamorphic rocks from the Monviso massif Lower Shear Zone (LSZ; Western Alps), recording evidence of an interface-parallel, channelized fluid flow near peak burial metamorphic conditions (∼550 °C and 2.7 GPa). We sampled variably metasomatized Fe-Ti metagabbros, hybrid (talc) schists and serpentinites containing sulfides supposed to preserve the aqueous fluid composition, as well as other alpine metagabbro, metabasalt and serpentinites from greenschist to eclogite-facies devoid of the studied metasomatic overprint.The millimeter to centimeter-sized sulfide crystals found in abundance within LSZ lithologies are mainly pyrites containing inclusions of the peak burial mineral assemblage (e.g. garnet, omphacite, rutile) indicating their crystallization at peak conditions or during incipient exhumation. The sulfides in the non-metasomatic metagabbros and metabasalts cover a narrow range in δ’34S of 0.89 ± 0.63 ‰ and Δ’33S of 0.017 ± 0.01 (n = 6) that could be inherited from hydrothermal sulfides formed on the seafloor. In contrast, the LSZ sulfides from the Fe-Ti metagabbros, serpentinites and hybrid schists (n = 24) are enriched in 34S and 33S (bulk δ’34S from 4.91 to 21.32 ‰ and Δ’33S from 0.02 to 0.06 ‰) compared to the sulfides from the non-metasomatic rocks. Mixing between reduced sulfur species cannot explain all the data without requiring an end-member composition as high as δ34S ∼ 22 ‰ and Δ33S ∼ 0.06 ‰, i.e. values rarely recorded by sulfides in the literature. Instead, we propose that this 33S-34S-enrichment results from open-system sulfate reduction to sulfides in aqueous fluids at 550°C, with an initial δ34S ∼ 12 ± 3 ‰ and Δ33S ∼ 0.025 ± 0.010 ‰. Because this signature is different from seawater sulfate, we suggest that sulfate was produced by hydrothermal sulfide oxidation during antigorite breakdown at 650°C, in agreement with Mg, Ni and Cr enrichments in the metasomatized HP mafic lithologies. This model is consistent with relatively oxidized 34S-enriched arc lavas and can potentially explain recycled sulfur with positive δ34S signature recorded by ocean island basalts.

Pressurized environments directly influence friction and wear of dry steel contacts—Investigations in a novel high fluid pressure tribometer

To reduce the usage of classical lubricants in deep drawing, a new tribological system based on volatile lubricants was developed. Therefore, a volatile medium is injected under high pressure into the interstice between drawing tool and sheet metal. Depending on temperature and pressure, the temporary lubricant may exist in its gaseous or liquid phase. In this study, a novel high fluid pressure tribometer was designed to investigate the friction and wear of dry steel contacts under comparable conditions like in dry deep drawing. Therefore, a new ball-on-disc tribometer was designed and integrated into a high-pressure vessel. To specifically investigate the effects of different environments (technical air, liquid and gaseous carbon dioxide, nitrogen, argon) at atmospheric and high pressure (0.1 MPa, 6 MPa) on tribology, the specimens and all components were operating unlubricated. During the experiments, the friction was measured continuously. Results show that the highest friction occurs in air and the lowest in carbon dioxide environment. Subsequent to the experiments, the wear of the specimens was assessed along with changes in surface chemistry related to tribochemical reactions. Therefore, the tribology of the dry sliding contacts is correlated to changes of the surface chemistry. Also differences as well as similarities regarding the different fluid environments are shown. As the results show, the differences between the media used are most pronounced at elevated pressure. Concluding, this work gives clear indications on the suitability of volatile lubricants in dry friction or rather gas lubrication, especially for dry deep drawing.

Mineral precipitation sequence from multi-stage fluids released by eclogite during high-pressure metamorphism

Abstract Arc magmas above subduction zones hold abundant fluid-mobile elements attributed to fluids released from the dehydrating subducted oceanic crust. However, the quantity of trace elements in the fluids and their evolution with the metamorphic processes during subduction and exhumation are still unclear. The precipitation sequence of vein minerals preserves the nature of multi-stage high-pressure (HP) metamorphic fluids and the fingerprint of mass exchange in deep subduction zones. In this contribution, we conducted detailed petrological studies and phase equilibria modeling on a unique HP omphacite-rich vein and its host eclogite from the Chinese southwestern Tianshan. The host eclogite consists mainly of garnet, omphacite, epidote, glaucophane, phengite, quartz, and rutile. Garnet in the eclogite records prograde subduction and early exhumation characterized by decompression heating at P-T conditions of ~2.4–2.6 GPa and 460–540 °C. The embedded omphacite-rich vein has similar mineral assemblage to the host eclogite. Garnet grains in this vein are predominantly distributed along or intersect the vein wall, which record similar eclogite-facies metamorphic conditions to that of the host eclogite. Omphacite is dominant in the vein, while epidote and glaucophane occur interstitially. Phase equilibria modeling reveals a sequential growth of garnet-dominated, omphacite-dominated, and epidote-dominated assemblages from fluids originating from the breakdown of different hydrous minerals. These lines of evidence suggest that the formation of multi-stage HP fluids are a continuous long-term process with a spontaneously short-distance transport and sequential mineral precipitation. Calculated fluid compositions demonstrate that the fluids released by lawsonite breakdown during exhumation have great potential to modify the trace element systematics of arc magmas. Our findings reveal the nature and evolution of multi-stage HP metamorphic fluids from internal sources during subduction and exhumation of oceanic crust, providing valuable insights into the chemical compositions of arc magmas.