High Pressure Resistance Research Articles

Superhydrophobicity With Self-Adaptive Water Pressure Resistance and Adhesion of Pistia Stratiotes Leaf.

Superhydrophobic surfaces are promising for optimizing amphibious aircraft by minimizing water drag and adhesion. Achieving this involves ensuring these surfaces can resist high liquid pressure caused by deep water and fluid flow. Maximizing the solid-liquid contact area is a common strategy to improve liquid pressure resistance. However, this approach inevitably increases solid-liquid adhesion, making it challenging to guarantee a trade-off between the two wetting characteristics. Here, it is found that the Pistia stratiotes leaf exhibits superhydrophobicity with high water pressure resistance and low adhesion, attributed to its self-adaptive deformable microstructure with unique re-entrant features. Under pressure, these microstructures deform to increase the solid-liquid contact area, thereby enhancing water pressure resistance. The re-entrant features elevate the deformation threshold, enabling higher modulus microstructures to achieve adaptive response. This facilitates the recovery of deformed microstructures, restoring the air layer and maintaining low adhesion. Following these concepts, Pistia stratiotes leaf-inspired surfaces are fabricated, achieving an 183% improvement in water impact resistance and an ≈80% reduction in adhesion after overpressure compared to conventional superhydrophobic surfaces. The design principles inspired by Pistia stratiotes promise significant advancements in amphibious aircraft and other trans-media vehicles.

Exploring the drag reduction caused by a combined spike and jet setup for a hypersonic blunt object at low elevations

Abstract When hypersonic vehicles fly at low altitudes during the end of the trajectory, they often face extremely high dynamic pressure and greater resistance. Studying the drag reduction features of the hypersonic vehicle at low altitudes is highly important. The Reynolds-averaged N-S equations are solved using the finite-volume method with the SST k-ω turbulence model. Numerical simulations are conducted on three-dimensional hypersonic flow fields involving spike and combined spike and jet configurations at low altitudes with hypersonic speeds to investigate drag reduction effects and analyze flow field characteristics. The data indicates that the presence of a spike can effectively reduce drag during low-altitude hypersonic flight. Enhancing the spike length, its drag reduction efficiency first increases and then slightly decreases. Enhancing the Mach number, the length of the spike that achieves the best drag reduction efficiency becomes longer. A spike and jet combination can enhance drag reduction efficiency when flying at an angle of attack. Enhancing the spike length or the pressure ratio in this configuration can enhance its effectiveness in reducing drag. The findings of this study provide practical guidance for developing drag-reduction strategies for hypersonic aircraft flying at low altitudes.

Study on axial and bending stiffness characteristics of reinforced S-shaped bellows

PurposeReinforced S-shape bellows are novel metal bellows with high pressure resistance. Displacement compensation ability is a key index in the design of metal bellows. Axial-tension-compression deformation and bending deformation are two typical displacement compensation forms. Thus, analysis of axial and bending stiffness is important in structure design.Design/methodology/approachIn this study, theory analytics of axial tension and compression stiffness of reinforced S-shaped bellows structure is derived, and the load-displacement relationship during axial deformation is obtained by correcting the geometric parameters of waveform during axial tension and compression deformations. On the basis of them, the relationships of bending stiffness with axial tensile and compression stiffness under the action of bending loading are constructed, and thus, the theory analytics of bending stiffness is realized for S-shaped bellows.FindingsThis theory analytics is verified by comparing the results of theory analytics with those of numerical simulation for a few typical examples. An investigation on the axial and bending non-linear mechanical behaviors of multi-layer-reinforced S-shaped bellows was also carried out by numerical simulation and experiment, and the experimental results verified the reliability of the analysis method.Originality/valueIt is found that non-linearity behavior occurs greatly during the first loading course of reinforced S-shaped bellows, and the structure is strain-strengthened due to plastic deformation; however, stable stiffness characteristic is exhibited during the succeeding cyclic-loading course.

Design and Calculation of Products from Composite Materials Using Software

This article analyzes six types of composite pipes that are good replacements for corrosive steel and metal pipes for oil, gas, and water. The analysis of the six samples of composite pipes was done using the software program Hoffman Engineering, which is intended for the design and calculation of various types of products made of composite materials. For the analysis of the six composite pipes, the same diameter and the same length were taken, and variable parameters are: the type of material from which the composite pipes are made (carbon/epoxy, carbon-glass/epoxy and glass/epoxy), and the angle of winding of the fibers (10º and 90º degrees). Using the Hoffman Engineering software package, an analysis of the durability of the six differently designed composite pipes at high internal pressure was performed. The same conclusion was obtained from all analyses: the high internal pressure resistance of composite pipes is highly dependent on the fiber winding angle and the type of fibers used. Composite pipes obtained with a fiber winding angle of 90º have twice the internal pressure resistance compared to composite pipes obtained with a fiber winding angle of 10º. Composite pipes based on carbon fibers have the highest resistance to internal pressure, then composite pipes based on hybrid materials (glass and carbon fibers) and finally composite pipes based on glass fibers. Finally, a comparison was made with the obtained laboratory results for the same composite pipes. The same conclusion was obtained from all analyses: the high internal pressure resistance of composite pipes is highly dependent on the fiber winding angle and the type of fibers used. The composite pipes obtained by this process are durable and resistant to very high pressures.

Dynamic Characteristics of Pressure-Balanced Metal Bellows in Fluid–Structure Interaction

As a flexible component in high-pressure vessels and pipeline systems, bellows experience significant fluid–structure interaction effects under high-speed internal fluids and external vibrations. Nevertheless, their dynamic response mechanisms coupled with fluid–structure interaction mentioned below have not yet been clarified so far. In this work, a novel pressure-balanced metal bellow (PBMB) for low-stiffness and high-pressure resistance is firstly proposed. Several fluid–structure interaction models were considered to study the dynamic response characteristics of the PBMB. An experimental platform associated with fluid–structure interaction was established to validate the effectiveness of its vibration attenuation performance. The results indicate that the PBMB has an obvious vibration attenuation effect in the range of 5–90[Formula: see text]Hz, and super-harmonic and sub-harmonic resonance phenomena occur in the range of 90–200[Formula: see text]Hz. Under constant fluid conditions, fluid density, viscosity, flow velocity, and pressure are positively correlated with the response amplitude of the PBMB. The response of the PBMB oscillates at the fluid entry point due to both pulsating flow velocity and pulsating pressure. After several cycles, the response caused by pulsating flow velocity gradually decays and stabilizes. Thus, the impact of pulsating frequency on the stability of the response of bellows is insignificant during the initial cycles.

Study on methane degradation by microbial agents based on chelating wetting agent carriers

Due to the low permeability characteristics of the deep gas-containing coal seam, the conventional prevention and control measures that cannot solve the problems of gas outbursts are unsatisfactory for the prevention and control of the coal and gas outbursts disaster. Therefore, in this study, a strain of methane-oxidizing bacteria M07 with high-pressure resistance, strong resistance, and high methane degradation rate was selected from coal mines. The growth and degradation abilities of M07 in chelating wetting agent solutions to assess its adaptability and find the optimal agent-to-M07 ratio. It provides a new method for integrating the reduction of impact tendency and gas pressure in deep coal mines. The experimental results show that M07 is a Gram-positive bacterium of the genus Bacillus, which has strong resistance and adaptability to high-pressure water injection. By degrading 70 mol of methane, M07 produces 1 mol of carbon dioxide, which can reduce gas pressure and reduce the risk of gas outbursts in coal mines. As the experiment proves, the best effect was achieved when the M07 concentration of the chelating wetting agent was 0.05%. The methane-oxidizing bacteria based on the chelating wetting agent as carriers prove a new prevention and control method for the integrated prevention and control of coal and gas outbursts in coal mines and also provide a new idea for microbial application in coal mine disaster control.

Novel membrane modifications for pressure retarded osmosis as a new way for sustainable power generation from salinity gradients

Pressure retarded osmosis (PRO) is a novel technology that allows power to be generated from high-salinity resources. To achieve a high power density, a high-salinity solution should be used on the draw side together with high hydraulic pressure, thus the PRO process requires a membrane that has high salt rejection and high pressure resistance. The reverse osmosis (RO) membranes can be potential candidates for the PRO process. In this study, commercial RO membranes with different surface modifications were examined: O2 plasma, polydopamine (PDA) and tannic acid (TA). Improved water permeability and salt rejection were obtained after modification. The membranes were also tested with a high salinity solution (175 g/L NaCl) in a PRO mode. Due to the improved water permeability and high salt rejection of the surface-modified membrane, the commercial RO membrane showed enhanced power density (3 W/m2) in comparison to the pristine membrane (2 W/m2).

Coevolution of superconductivity and Hall coefficient with anisotropic lattice shrinkage in compressed KCa2Fe4As4F2

Abstract The stability of superconductivity in superconductors is widely recognized to be determined by various factors, including charge, spin, orbit, lattice, and other related degrees of freedom. Here, we report our findings on the pressure-induced coevolution of superconductivity and Hall coefficient in KCa2Fe4As4F2, an iron-based superconductor possessing a hybrid crystal structure combining KFe2As2 and CaFeAsF. Our investigation, involving high-pressure resistance, Hall effect and x-ray diffraction (XRD) measurements, allows us to observe the connection of the superconductivity and Hall coefficient with the anisotropic lattice shrinkage. We find that its ambient-pressure tetragonal (T) phase presents a collapse starting at around 18 GPa, where the sign of the Hall coefficient (R H) changes from positive to negative. Upon further compression, both superconducting transition temperature (T c) and R H exhibit a monotonous decrease. At around 41 GPa, the superconductivity is completely suppressed (T c = 0), where the parameter a begins to decline again and the Hall coefficient remains nearly unchanged. Our experiment results clearly demonstrate that the pressure-induced anisotropic lattice collapse plays a crucial role in tuning the interplay among multiple degrees of freedom in the superconducting system and, correspondingly, the stability of the superconductivity.

Histone β-hydroxybutyrylation-mediated Chromatin Remodeling Upregulates β-oxidation of Fatty Acids and Attenuates Metabolic Syndrome

Center for Hypertension and Precision Medicine, Department of Physiology and Pharmacology, University of Toledo, Toledo, OH Introduction: Metabolic syndrome (MetS) is a cluster of metabolic dysregulations including high blood pressure (BP), dyslipidemia, central obesity, hyperglycemia, and insulin resistance. Regular exercise is one of the lifestyle modifications known to prevent MetS by the generation of ketone bodies. Precisely how ketone bodies operate to lower MetS is largely unknown. Previously, we demonstrated that the ketone body, β-hydroxybutyrate, is a potent anti-hypertensive metabolite. β-hydroxybutyrate has been recently recognized to epigenetically modify histones by β-hydroxybutyrylation. Using assay for transposase-accessible chromatin with sequencing and chromatin immunoprecipitation assays, we found that histone β-hydroxybutyrylation causes chromatin remodeling and exposes regions for transcription of genes for β-oxidation of fatty acids. Therefore, we hypothesized that β-hydroxybutyrate alleviates MetS via histone β-hydroxybutyrylation-mediated transcriptional upregulation of β-oxidation of fatty acids. To test this hypothesis, we examined the epigenetic effect of increasing systemic β-hydroxybutyrate in a genetic rat model of MetS inbred in our laboratory, the low-capacity runner (LCR/Tol) rats. Methods: Randomly selected two groups of six months old female LCR/Tol rats (n=5/group) were surgically implanted with radiotelemetry transmitters for BP measurement. The control group was given water, whereas the experimental group was given water containing 20% v/v of 1,3-butanediol (1,3-BD), which is a precursor of β-hydroxybutyrate for 10 weeks. Following euthanasia, sera and tissues were harvested. Histones were isolated and subjected to western blotting for quantitation of β-hydroxybutyrylation. Results: Compared to the control group, rats given 1,3-BD had a significantly increased circulating β-hydroxybutyrate (mean 1.98 mM vs 0.71 mM, p<0.05), lower body weight (mean 231.6 gm vs 248.4 gm, p<0.05), lower fasting glucose (mean 79.60 mg/dl vs 100.8 mg/dl, p<0.05) and lower 24-hour average systolic BP (116±2 mmHg vs. 120±2 mmHg, p<0.05). Interestingly, histones isolated from the experimental group with higher circulating β-hydroxybutyrate also displayed a marked increase in β-hydroxybutyrylation (mean 0.82 vs 0.22, p<0.01). Further, the target transcriptional genes of histone β-hydroxybutyrylation, 3-hydroxy-3-methylglutaryl-CoA synthase 2 (Hmgcs2) and cytochrome P450 family 2 subfamily d polypeptide 4 (Cyp2d4) were both significantly upregulated in the experimental group (p<0.01). However, markers of liver injury, alanine transaminase, alkaline phosphatase, aspartate transaminase, and total bile acid levels, were comparable between the two groups, indicating no liver damage. Conclusion: This is the first study to demonstrate that enhanced systemic β-hydroxybutyrate attenuates MetS by histone β-hydroxybutyrylation-mediated chromatin remodeling to upregulate the transcription of Hmgcs2 and Cyp2d4 to promote β-oxidation of fatty acids. Further, our results demonstrate that for individuals with MetS who may be unable to exercise, utilizing 1,3-BD could serve as an alternate source to combat the MetS ameliorating benefits of the ketone body β-hydroxybutyrate. Funding Sources: Authors acknowledge the National Institutes of Health for funding support to Bina Joe (R01HL1430820). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

From Insulator to Superconductor: A Series of Pressure-Driven Transitions in Quasi-One-Dimensional TiS3 Nanoribbons.

Transition metal trichalcogenides (TMTCs) offer remarkable opportunities for tuning electronic states through modifications in chemical composition, temperature, and pressure. Despite considerable interest in TMTCs, there remain significant knowledge gaps concerning the evolution of their electronic properties under compression. In this study, we employ experimental and theoretical approaches to comprehensively explore the high-pressure behavior of the electronic properties of TiS3, a quasi-one-dimensional (Q1D) semiconductor, across various temperature ranges. Through high-pressure electrical resistance and magnetic measurements at elevated pressures, we uncover a distinctive sequence of phase transitions within TiS3, encompassing a transformation from an insulating state at ambient pressure to the emergence of an incipient superconducting state above 70 GPa. Our findings provide compelling evidence that superconductivity at low temperatures of ∼2.9 K is a fundamental characteristic of TiS3, shedding new light on the intriguing high-pressure electronic properties of TiS3 and underscoring the broader implications of our discoveries for TMTCs in general.

Insights into micro-structure and separation mechanism of benzimidazole-linked polymer membrane for H2/CO2 separation

Separation of hydrogen from carbon dioxide for sustainable H2 production and CO2 capture still faces great challenges due to the smaller size of H2 and higher condensability of CO2. Herein, a high-performance benzimidazole-linked polymer (BILP) membrane for hydrogen separation was directly prepared on α-Al2O3 substrate through a facile interfacial polymerization approach at room temperature. The separation performance of the BILP membrane were regulated by controlling the reaction time and the microstructure was systematically characterized. Molecular simulations were performed to deep understand the separation mechanism in the BILP membrane. The best performance membrane displays an extraordinary mixed gas selectivity of 40 for H2/CO2 together with outstanding H2 permeance of 250 gas permeation units (GPU) at 473 K, far exceeding the Robeson’s upper bound. Besides, the membrane can withstand high temperature and pressure, and also shows good H2/N2 and H2/CH4 selectivity. The excellent separation performance, coupled with high temperature and pressure resistance and easy preparation, render BILP membranes great potential for economic H2 purification, H2 recovery, and natural gas treatment.

ZIF-8 functionalized S-tapered fiber-optic sensor for polystyrene nanoplastics detection by electrostatic adsorption

Microplastic (MP) residues in marine have become an increasingly serious environmental pollution issue, and in recent years the detection of MPs in marine started to attract worldwide research interests. Optical-fiber-based environmental sensors have been extensively employed for their several merits such as high sensitivity, pressure resistance, compactness and ease of constructing communication networks. However, fiber-optic refractive index sensors are not specifically developed for distinguishing MPs from other inorganic particles suspended in water. In this paper, an metal-organic framework (MOF) ZIF-8 functionalized S-tapered fiber (STF) sensor is proposed for specific detection of polystyrene nanoplastics (PSNPs) in aqueous environment. ZIF-8 coordination nanoporous polymers with different film thickness were immobilized over the surface of the fabricated STF structure based on self-growth technique and yielding a large surface area over the sensor surface. High sensitivity detection can be achieved by converting the concentration perturbation of PSNPs into evanescent waves over the ZIF-8 functionalized STF surface through the strong electrostatic adsorption effect and π-π stacking, while the fabricated sensor is insensitive to gravels with silica as the primary component in water. It is found that the proposed detector with 18 film layers achieves a sensitivity up to 114.1353nm/%(w/v) for the PSNPs concentration range of 0.01 %(w/v) to 0.08 %(w/v).

Surrogate indices of insulin resistance using the Matsuda index as reference in adult men-a computational approach.

Overweight and obesity, high blood pressure, hyperglycemia, hyperlipidemia, and insulin resistance (IR) are strongly associated with non-communicable diseases (NCDs), including type 2 diabetes, cardiovascular disease, stroke, and cancer. Different surrogate indices of IR are derived and validated with the euglycemic-hyperinsulinemic clamp (EHC) test. Thus, using a computational approach to predict IR with Matsuda index as reference, this study aimed to determine the optimal cutoff value and diagnosis accuracy for surrogate indices in non-diabetic young adult men. A cross-sectional descriptive study was carried out with 93 young men (ages 18-31). Serum levels of glucose and insulin were analyzed in the fasting state and during an oral glucose tolerance test (OGTT). Additionally, clinical, biochemical, hormonal, and anthropometric characteristics and body composition (DEXA) were determined. The computational approach to evaluate the IR diagnostic accuracy and cutoff value using difference parameters was examined, as well as other statistical tools to make the output robust. The highest sensitivity and specificity at the optimal cutoff value, respectively, were established for the Homeostasis model assessment of insulin resistance index (HOMA-IR) (0.91; 0.98; 3.40), the Quantitative insulin sensitivity check index (QUICKI) (0.98; 0.96; 0.33), the triglyceride-glucose (TyG)-waist circumference index (TyG-WC) (1.00; 1.00; 427.77), the TyG-body mass index (TyG-BMI) (1.00; 1.00; 132.44), TyG-waist-to-height ratio (TyG-WHtR) (0.98; 1.00; 2.48), waist-to-height ratio (WHtR) (1.00; 1.00; 0.53), waist circumference (WC) (1.00; 1.00; 92.63), body mass index (BMI) (1.00; 1.00; 28.69), total body fat percentage (TFM) (%) (1.00; 1.00; 31.07), android fat (AF) (%) (1.00; 0.98; 40.33), lipid accumulation product (LAP) (0.84; 1.00; 45.49), leptin (0.91; 1.00; 16.08), leptin/adiponectin ratio (LAR) (0.84; 1.00; 1.17), and fasting insulin (0.91; 0.98; 16.01). The computational approach was used to determine the diagnosis accuracy and the optimal cutoff value for IR to be used in preventive healthcare.

Connection strength analysis and prediction of external swaging based on tube deformation measurement

Fittings have extensive use in the aerospace, automotive, and other industries as they serve as sealing and connecting components for tube systems. External Swaging (ES) forming creates a permanent joint through plastic deformation of the metal. This technique is not dependent on the tube's wall thickness and offers benefits such as high-pressure resistance and effective sealing. Using the forming process of a 10 mm Ti-3Al-2.5 V tube with an adapted 21-6-9 fitting as an illustration, a three-dimensional finite element model for the entire assembly was developed. The model consists of the tube, fitting, elastic clamp, and crimping tool. The formation mechanism and joint strength of external swaging are analyzed by numerical simulation and experimental testing. The results show that during the extrusion process, the tangential contact between the extrusion tool and the elastic clamps converts external radial loads into circumferential loads, resulting in circumferential strains in the tube. Circumferential strain creates an arched sealing area between the tube and fitting contact surfaces, providing sealing and joint strength. The joint strength of 10.60 kN was determined through finite element simulation. The load required for forming is determined by analysis to be 80.13 kN. and the relationship between squeeze load, crimp volume and joint strength is clarified. The study revealed that the height of the arch area aligns with the connection strength's change rule concerning extrusion load, fitting the two found that when the external extrusion load changes, the two are linear rule of changing. Based on this, a method is suggested for forecasting the strength of a joint by measuring the height of the arch in the tube after forming.

Swimming Exercise Protocol and Care Methods for Pregnant Rats.

The developmental origins of health and disease concept highlights the impact of early environments on chronic non-communicable diseases like diabetes, cardiovascular disease, and cancer. Studies using animal models have investigated how maternal factors such as undernutrition, overnutrition, obesity, and exposure to chemicals or hypoxia affect fetal development and offspring health, leading to issues like low birth weight, high blood pressure, dyslipidemia, and insulin resistance. Given the increasing prevalence of overweight and obesity among reproductive-age women, effective interventions are critical. Maternal exercise during pregnancy has emerged as a key intervention, benefiting both mother and offspring and reducing the risk of disease. This study compares the differences of three exercise models on pregnant rats: voluntary wheel running, motorized treadmills, and swimming. Swimming is the most beneficial option due to its safe and controlled intensity levels. This protocol details the rat breeding methods, swimming training during pregnancy, and post-breeding nursing protocols. This model, suitable for various rat and mouse species, is useful for studying the benefits of maternal exercise on offspring health and intergenerational wellness.

Oral contraceptives in adolescents: a retrospective population-based study on blood pressure and metabolic dysregulation.

This study aimed to explore the relationship between oral contraceptive use and blood pressure values and in a national cohort of women adolescents and to investigate the level of coexistence of the high blood pressure levels, dyslipidemia or insulin resistance. This is a retrospective cohort study that evaluated data form 14,299 adolescents aged 14 to 17years. Crude and race-and age-adjusted analyses were performed using Poisson regression to estimate the prevalence ratios. Data clustering analysis was performed using machine learning approaches supported by an unsupervised neural network of self-organizing maps. We found that 14.5% (n = 2076) of the women adolescents use oral contraceptives. Moreover, an increased prevalence of high blood pressure, dyslipidemia, and insulin resistance (all P < 0.001) was observed among adolescents who use oral contraceptives as compared to those who do not. Our analysis also showed that 2.3% of adolescents using oral contraceptives had both high blood pressure levels and dyslipidemia, whereas 3.2% had high blood pressure levels combined with insulin resistance (all P < 0.001). The algorithmic investigative approach demonstrated that total cholesterol, LDLc, HDLc, insulin, and HOMA-IR were the most predicted variables to assist classificatory association in the context of oral contraceptive use among women adolescents with high blood pressure. These findings suggest that oral contraceptives were associated with an increased prevalence of high blood pressure, dyslipidemia, and insulin resistance among women adolescents. Although the indication of this therapy is adequate to avoid unintended pregnancies, their use must be based on rigorous individual evaluation and under constant control of the cardiometabolic risk factors.

Molecular-level manipulation of polyamide membranes for high-performance H2/CO2 separation

The preparation of high-performance H2/CO2 polymer separation membranes is an urgent need to reduce the global greenhouse effect. Here, polyamide (PA) membranes with excellent H2/CO2 separation performance are produced using a facile interfacial polymerization (IP) plus heat treatment approach. The synergistic effect of the substrate-confinement and the control of the d-spacing and crosslinking degree of PA membranes creates sufficient H2 selective channels. The effects of test parameters such as feed temperature and feed pressure on membrane performance were investigated. The ultra-high H2/CO2 selectivity of 110 with excellent H2 permeance of 180 GPU is observed at 150 °C and feed pressure of 2 bar. In addition, PA membranes have high-pressure resistance (16 bar), high-temperature resistance (300 °C), and attractive durability (210 h). The excellent performance and facile preparation process make them expected to be one of the most promising membranes for H2/CO2 separation.

Optimizing synthetic core plugs: Sintered glass beads and sand particles for natural rock property replication in fluid flow and reservoir studies

Developing reliable synthetic cores that accurately mimic natural rock properties is crucial for studying fluid flow and reservoir processes. This paper presents a novel study for fabricating synthetic core samples by fusing glass beads and sand particles within cylindrical molds. Various synthetic core production and characterization factors were explored, including material selection, fabrication parameter optimization, pore size distribution, and capillary behavior analysis.Ceramic tubes were ideal for core fabrication due to their high-temperature tolerance, durability, and reusability. Quartz glass beads were preferred for their transparency and enhanced heat stability. Varying the size and shape of the glass beads influenced porosity, with round particles having lower porosity and angular particles showing higher porosity. The packing procedure and furnace type affected porosity and permeability, with tightly packed arrangements resulting in lower values. Optimal sintering conditions were identified at 680 °C for 15 min, resulting in high porosity and permeability. Incorporating sand particles at a 1:6 sand-to-glass-bead ratio enhanced core stability under challenging conditions (740 °C), achieving high-pressure resistance (≈15,000 psi) and tighter cores with lower porosity (≈11%) and permeability (≈5 mD) compared to cores made solely of glass beads, which had lower pressure resistance (≈2300 psi) and higher porosity (≈31%) and permeability (≈3190 mD). Synthetic cores demonstrated exceptional stability under fluid flow conditions, with minimal property changes (≈<1%) and wettability alterations comparable to natural cores. The capillary pressure study confirmed the similarity of synthetic cores to real cores, revealing variations in pore sizes and residual mercury saturations.Overall, this innovative study highlights the potential of sintered glass beads for producing better synthetic core plugs. Including sand particles at elevated temperatures and extended retention times enables the production of tighter synthetic core plugs. The findings confirm the essential role of sintered glass beads in replicating natural rock properties and studying fluid flow at reservoir conditions.

Analysis of Springback Characteristics of Bending Unloading for Stainless Steel tubes

Stainless steel tubes are widely used in piping systems in aviation, aerospace and other high-tech fields because of their high strength, excellent corrosion and high-pressure resistance, and good resistance to high-temperature oxidation. This paper takes 304 stainless steel pipe as the research object, based on ABAQUS finite element platform, the springback behaviour of stainless steel pipe in the process of precise bending and forming has been studied in depth. The results show that: pipe bending unloading bending springback angle increases with the increase of the bending angle. The results of the study have important theoretical and practical significance for improving the accurate forming and springback of stainless steel tube bending.

Effects of High-Load Bench Press Training with Different Blood Flow Restriction Pressurization Strategies on the Degree of Muscle Activation in the Upper Limbs of Bodybuilders.

Background: The aim of this study was to investigate the effects of different pressurization modes during high-load bench press training on muscle activation and subjective fatigue in bodybuilders. Methods: Ten bodybuilders participated in a randomized, self-controlled crossover experimental design, performing bench press training under three different pressurization modes: T1 (low pressure, high resistance), T2 (high pressure, high resistance), and C (non-pressurized conventional). Surface EMG signals were recorded from the pectoralis major, deltoid, and triceps muscles using a Delsys Trigno wireless surface EMG during bench presses. Subjective fatigue was assessed immediately after the training session. Results: (1) Pectoralis major muscle: The muscle activation degree of the T1 group was significantly higher than that of the blank control group during the bench press (p < 0.05). The muscle activation degree of the T2 group was significantly higher than that of the C group during the bench press (p < 0.05). In addition, the muscle activation degree of the T2 group was significantly higher than that of the T1 group during the first group bench press (p < 0.05). (2) Deltoid muscle: The muscle activation degree of the T2 group during the third group bench press was significantly lower than the index values of the first two groups (p < 0.05). The muscle activation degree in the experimental group was significantly higher than that in the C group (p < 0.05). The degree of muscle activation in the T2 group was significantly higher than that in the T1 group during the first bench press (p < 0.05). (3) Triceps: The muscle activation degree of the T1 group was significantly higher than the index value of the third group during the second group bench press (p < 0.05), while the muscle activation degree of the T2 group was significantly lower than the index value of the first two groups during the third group bench press (p < 0.05). The degree of muscle activation in all experimental groups was significantly higher than that in group C (p < 0.05). (5) RPE index values in all groups were significantly increased (p < 0.05). The RPE value of the T1 group was significantly higher than that of the C group after bench press (p < 0.05). The RPE value of the T1 group was significantly higher than that of the C group after bench press (p < 0.05). In the third group, the RPE value of the T1 group was significantly higher than that of the C and T2 groups (p = 0.002) (p < 0.05). Conclusions: The activation of the pectoralis major, triceps brachii, and deltoid muscles is significantly increased by high-intensity bench press training with either continuous or intermittent pressurization. However, continuous pressurization results in a higher level of perceived fatigue. The training mode involving high pressure and high resistance without pressurization during sets but with 180 mmHg occlusion pressure and pressurization during rest intervals yields the most pronounced overall effect on muscle activation.