Pressure Resistance Research Articles

Racial differences in baroreflex function: Implications for the cardiovascular conundrum

Study objectiveAfrican Americans (AAs) show early signs of vascular dysfunction paired with elevated blood pressure (BP) and total peripheral resistance (TPR), which is thought to underlie their increased rates of cardiovascular health complications relative to European Americans (EAs). AAs paradoxically have higher cardiac vagal tone, indexed by heart rate variability (HRV), which is cardio-protective. This paradox has been termed the Cardiovascular Conundrum. The physiological mechanism underlying this phenomenon is not well understood. We examined race differences in baroreflex function, which might be an important mechanism underlying the Cardiovascular Conundrum. DesignParticipants completed a 5-minute baseline period where resting cardiac metrics were assessed. SettingLaboratory. Participants130 college-aged individuals (54 women, 57 AAs). Main outcome measuresBaroreflex function was indexed as baroreflex sensitivity (BRS; the magnitude of changes in cardiovascular activity in accordance with BP changes) and effectiveness (BEI; the ratio of BP changes that elicit changes in cardiovascular activity) in the cardiac, vascular, and myocardial limbs. Results and conclusionsResults showed AAs to have higher HRV and cardiac BRS in comparison to EAs, suggesting the baroreflex is more sensitive to correcting the heart period for changes in BP among AAs compared to EAs. However, AAs showed lower vascular BEI relative to EAs, suggesting less effective control of TPR. In sum, lower BEI in the vascular branch might be an important mechanism underlying the Cardiovascular Conundrum (i.e., higher HRV and BP) and by extension, health disparities in cardiovascular diseases between AAs and EAs.

Optimization and predictive modeling of membrane based produced water treatment using machine learning models

Membrane technology has become a crucial solution for treating produced water, playing a vital role in resource recovery and environmental preservation. The use of advanced Artificial Intelligence (AI) technique such as Machine Learning (ML) has introduced an innovative approach to define and model these treatment procedures such as trans-membrane pressure (TMP) and total membrane resistance. The research focuses specifically on the utilization of Artificial Neural Network (ANN) and Extreme Gradient Boosting (XGBoost) model to improve the precision and effectiveness of produced water treatment using membrane technology. Also, the study presented explores how the Artificial Neural Network (ANN) framework excels in predictive insights and process modeling, optimizing operational parameters in membrane-based treatment setups. Furthermore, integrating the Extreme Gradient Boosting (XGBoost) model highlights its ability to enhance system performance, providing accurate predictions and better control in complex treatment processes. It presents comprehensive research of combining Artificial Neural Network (ANN) and Extreme Gradient Boosting (XGBoost) model with membrane technology for produced water treatment, emphasizing their potential to improve optimization techniques and modeling approaches, ultimately enhancing water treatment efficiency and sustainability. Both the Artificial Neural Network (ANN) and Extreme Gradient Boosting (XGBoost) models achieved an impressive R-squared (R2) scores of 0.754, and 0.97 for Transmembrane Pressure (TMP), and 0.95 and 0.81 for Total Resistance prediction respectively.

Comparison of ePTFE membranes with fluorine-free alternatives considering durability of laminated fabrics using hydrostatic pressure testing

Pleasant wearing comfort is achieved using laminated fabrics containing a waterproof and breathable membrane. The most used membrane type is expanded polytetrafluoroethylene. Due to the negative impact of perfluoroalkyl and polyfluoroalkyl substances on the environment, fluorine-free alternative materials are necessary. In this work, alternative membrane materials, polyurethane and polyethylene terephthalate, were compared with expanded polytetrafluoroethylene. First, the mass per unit area, thickness, tensile properties, water vapor resistance, and hydrostatic pressure of corresponding laminates were determined. Furthermore, their durability, which is an essential aspect of sustainability, was investigated. Therefore, they were hydrolyzed, weathered, washed, and incorrectly treated (e.g. washed with fabric softener) and then investigated for hydrostatic pressure resistance, by scanning electron microscopy, infrared spectroscopy, and digital microscopy. It was shown that polyethylene terephthalate and expanded polytetrafluoroethylene are comparable with respect to breathability, waterproofness (>20 bar), and durability. However, the hydrostatic pressure resistance (approximately 11 bar) and the water vapor resistance values (>23 m2 · Pa · W−1) of microporous polyurethane membranes are poorer, but they still provide suitable alternatives. In addition, a beginning degradation of polyurethane could be proved after hydrolysis and weathering. Furthermore, the deposition of calcium salts on all membranes was observed after washing with tap water, fabric softener, and washing agents.

Automated assessment of hydrostatic pressure resistance in woven fabrics using the enhanced YOLOv8 network

Hydrostatic pressure resistance serves as a crucial metric in the assessment of water resistance in woven fabrics. The expeditious, precise, and efficient conduct of hydrostatic pressure tests holds paramount importance in advancing the progress and production of high-performance textiles. Addressing the challenges posed by intricate printed patterns on woven fabrics, and the presence of small, widely scattered water droplets, the study leverages the enhanced YOLOv8 model to develop a machine vision-based automated detection technique for assessing water resistance in woven fabric. The proposed method incorporates convolutional block attention module attention mechanisms into the backbone and neck network, replaces the path aggregation network structure of YOLOv8 with the bidirectional feature pyramid network structure, and introduces a dedicated detection head for small targets. These enhancements facilitate accurate identification of water outlet points on the woven fabric and precise recording of frame positions, enabling the precise measurement of hydrostatic pressure. Validation of the proposed model is conducted through a series of comparative experiments utilizing a self-collected dataset. The experimental results underscore the exemplary performance of the proposed model, evidenced by an AP0.5 score of 92.18%, showcasing superior overall efficacy in comparison with alternative models. Notably, the target localization time error is found to be less than 2 s when contrasted with manual detection. This method substantially enhances the accuracy of water droplet detection and localization in hydrostatic pressure resistance testing of woven fabric, characterized by complex surface patterns, thereby contributing to refinement of hydrostatic pressure testing methodologies in woven fabric analysis.

RIGHT VENTRICULAR DYSFUNCTION AND TRICUSPID VALVE SURGICAL CORRECTION: ROOM FOR STRESS ECHOCARDIOGRAPHY?

Abstract We report the case of a 50–years–old young woman with multi–operated rheumatic valvular heart disease; aortic, mitral, and tricuspid commissurotomy (1994); aortic valve replacement with bioprosthesis for endocarditis (1998); mitro–aortic replacement with mechanical prosthesis and tricuspid valve plastic repair (1999); mitral valve replacement and re–do of tricuspid plastic repair (2003). Concomitant conduction pathway disease (BAV II type 1 and RBB). The patient was admitted in June 2023 for wet & warm NYHA IV right heart failure with severe peripheral congestion and ascites. On echocardiography: LV with systo–diastolic compression, EF 51%; normo–functioning aortic prosthesis; dilated (TDA 24 cm2), hypokinetic (TAPSE 9mm,S‘ 4 cm/s,FAC 25%) right ventricole (RV), with poor load adaptation (load adaptation index 16, RVCPI 108 mm*mmHg, ePAPI 1.1); torrential IT, caval plethora with systolization of hepatic venous flow. Medical therapy was initiated with intravenous bolus diuretics, nitroglycerin and inotropic support (dobutamine 2.5 y). In order to define the best therapeutic strategy in the persistence of torrential IT and RV dysfunction we performed: trans–oesophageal echocardiography, showed massive IT from ring dilatation and wide flail of the septal flap not suitable for edge–to–edge correction, total–body angioTC, with no relevant findings, right cardiac catheterization, which documented pulmonary pressure and arteriolar resistances within limits (wedge 12 mmHg,PAP25/15/18 mmHg,RAP 11 mmHg,PAPI 0. 9,RVSWI 4.8) with reduced cardiac index (2.14 l/min/cm2) and stress–echocardiography with dobutamine that showed presence of RV contractile reserve (FAC 28%>39%). In consideration of the functional properties of the tricuspid valve, absence of pulmonary hypertension and given the presence of RV contractile reserve, patient underwent tricuspid valve replacement surgery with a bioprosthesis (SJ Epic 27 mm) in mini–thoracotomy with smooth postoperative course. At 3 months follow–up showed functional recovery (NYHA II), with good prosthetic function and partial reverse remodeling of the RV (TDA 14 cm2, FAC of 30%). In conclusion, by documenting right ventricular contractile reserve, stress echocardiography proved to be an important aid in predicting absence of RV failure in the immediate post–surgical period, presenting attractive prospects in the assessment of RV functional reserve in patients undergoing to corrective tricuspidal surgery.

Enhancement of bursting pressure resistance of braid-reinforced polyether sulfone hollow fiber composites

Enhancement of bursting pressure resistance of braid-reinforced polyether sulfone hollow fiber composites

Transient heat stress protects from severe endothelial damage and dysfunction during prolonged experimental ex-vivo lung perfusion.

The pulmonary endothelium is the primary target of lung ischemia-reperfusion injury leading to primary graft dysfunction after lung transplantation. We hypothesized that treating damaged rat lungs by a transient heat stress during ex-vivo lung perfusion (EVLP) to elicit a pulmonary heat shock response could protect the endothelium from severe reperfusion injury. Rat lungs damaged by 1h warm ischemia were reperfused on an EVLP platform for up to 6h at a constant temperature (T°) of 37°C (EVLP37°C group), or following a transient heat stress (HS) at 41.5°C from 1 to 1.5h of EVLP (EVLPHS group). A group of lungs exposed to 1h EVLP only (pre-heating conditions) was added as control (Baseline group). In a first protocol, we measured lung heat sock protein expression (HSP70, HSP27 and Hsc70) at selected time-points (n=5/group at each time). In a second protocol, we determined (n=5/group) lung weight gain (edema), pulmonary compliance, oxygenation capacity, pulmonary artery pressure (PAP) and vascular resistance (PVR), the expression of PECAM-1 (CD31) and phosphorylation status of Src-kinase and VE-cadherin in lung tissue, as well as the release in perfusate of cytokines (TNFα, IL-1β) and endothelial biomarkers (sPECAM, von Willebrand Factor -vWF-, sE-selectin and sICAM-1). Histological and immunofluorescent studies assessed perivascular edema and formation of 3-nitrotyrosine (a marker of peroxinitrite) in CD31 lung endothelium. HS induced an early (3h) and persisting expression of HSP70 and HSP27, without influencing Hsc70. Lungs from the EVLP37°C group developed massive edema, low compliance and oxygenation, elevated PAP and PVR, substantial release of TNFα, IL-1β, s-PECAM, vWF, E-selectin and s-ICAM, as well as significant Src-kinase activation, VE-cadherin phosphorylation, endothelial 3-NT formation and reduced CD31 expression. In marked contrast, all these alterations were either abrogated or significantly attenuated by HS treatment. The therapeutic application of a transient heat stress during EVLP of damaged rat lungs reduces endothelial permeability, attenuates pulmonary vasoconstriction, prevents src-kinase activation and VE-cadherin phosphorylation, while reducing endothelial peroxinitrite generation and the release of cytokines and endothelial biomarkers. Collectively, these data demonstrate that therapeutic heat stress may represent a promising strategy to protect the lung endothelium from severe reperfusion injury.

Relative Fundamental Frequency: Only for Hyperfunctional Voices? A Pilot Study.

(1) Background: Assessing phonatory disorders due to laryngeal biomechanical alterations requires aerodynamic analysis, assessing subglottic pressure, transglottic flow, and laryngeal resistance. This study explores whether the acoustic parameter, the relative fundamental frequency (RFF), can be studied using the current acoustic analysis protocol at the University of Navarra's voice laboratory and its association with pathologies linked to laryngeal biomechanical alterations. (2) Methods: A retrospective cohort study included patients diagnosed with muscular tension dysphonia, organic lesions of the vocal fold, and vocal fold paralysis (VFP) at the Clínica Universidad de Navarra from 2019 to 2021. Each patient underwent endoscopic laryngeal exploration, followed by acoustic study, RFF calculation, and an aerodynamic study. Additionally, a control group was recruited. (3) Results: 79 patients and 22 controls were studied. Two-way ANOVA showed significant effects for groups and cycles in offset and onset cycles. Statistically significant differences were observed in cycle 1 onset among all groups and in cycles 1 and 2 between the control group and non-healthy groups. (4) Conclusions: RFF is a valuable indicator of phonatory biomechanics, distinguishing healthy and pathological voices and different disorders. RFF in onset cycles offers a cost-effective, accurate method for assessing biomechanical disorders without complex aerodynamic analyses. This study describes RFF values in VFP for the first time, revealing differences regardless of aerodynamic patterns.

Theoretical analyses and experimental study on the factors influencing the pressure resistance of the magnetorheological grease seal with pinch mode pole piece

This paper mainly focuses on experimental research and theoretical analysis on the pressure resistance capability of magnetorheological grease rotary shaft sealing with pinch mode pole piece structure. Combining magnetorheological grease and pinch mode pole piece structure, the using of permanent magnet as magnetic source is aiming to reduce the lag of yield stress establishment and release. Herein, the micro-nano composite magnetorheological grease was prepared. Right after the synthesis process, its magnetization properties and rheological properties were scientifically and systematically characterized. The influence of different gaps and tooth widths on the magnetic induction intensity is analyzed by finite element method. Based on the theoretical method, the pressure resistance capacity induced by magnetic force is calculated. By comparing the theoretical calculation and experimental results of the pressure resistance, the cause of error and failure is analyzed.

Serial invasive hemodynamics and clinical characteristics of patients with shock with and without invasive mechanical ventilation

Abstract Funding Acknowledgements None. Background Invasive mechanical ventilation (IMV) is commonly used in the Cardiac Intensive Care Unit (CICU) in patients with cardiogenic shock (CS). IMV causes hemodynamic changes that may impact outcomes based upon a patient’s profile. Our aim is to characterize the clinical profile and detailed serial hemodynamic parameters in the first 24-hours according to the use of IMV in patients with shock admitted to the CICU. Methods Retrospective analysis of consecutive patients with shock admitted to the CICU at Bellevue Hospital, undergoing pulmonary artery catheter (PAC) placement within the first 24 hours of admission, from February 2022 to June 2023. Clinical characteristics, as well as specific hemodynamic parameters collected and curated at times 0, 6, 12, 18 and 24 hours were from PAC placement compared between patients with and without IMV. Results A total of 101 patients were included (95% with cardiogenic shock), 59 receiving IMV (age 64 ± 15, 24% women) and 42 non-intubated (61 ± 13, 33% women). Non-intubated patients had higher prevalence of hypertension, prior coronary artery disease and heart failure with reduced ejection fraction (HFrEF), while acute coronary syndromes (44%) and cardiac arrest (12%) were more common causes of admission in patients undergoing IMV. Mixed shock predominated in IMV patients (51 vs 17%, p <0.001), whereas cardiogenic shock (CS) was more common in non-intubated patients (83 vs 41%, p <0.01). Patients with acute myocardial infarction CS (AMI-CS) were more likely to undergo IMV, while patients with heart failure CS (HF-CS) were more likely to be non-intubated. Patients undergoing IMV were more likely to have mechanical circulatory support (MCS) and ventricular dilatation compared to non-intubated patients (LVEDD 5.7 cm vs 4.9 cm, p 0.002). Patients undergoing IMV had a higher incidence of severe shock compared to the non-intubated group (31% vs 19% SCAI Shock D), higher lactate levels and greater use of vasoactive drugs (figure 1A). Patients undergoing IMV had significant improvements in cardiac power output (CPO), diastolic blood pressure and systemic vascular resistance (SVR) (figure 1B). Shock severity by SCAI SHOCK classification had a more notable improvement at 24 hours in patients with IMV compared to non-intubated patients (figure 1C), with a non-statistically significant improvement in lactate clearance in the first 24 hours (Figure 1D). Conclusions IMV in patients with CS is more commonly seen in patients with AMI-CS and among those with higher baseline shock severity and greater use of vasoactive medications. IMV is associated with significant improvements in shock severity, CPO and SVR at 24 hours when compared to patients with shock who are not intubated, which could be related to higher use of vasopressors. Further investigations are warranted to understand the impact of IMV on outcomes of patients with CS and how they might vary according to hemodynamic profile.

Robust and Superhydrophobic Polydimethylsiloxane/Ni@Ti3C2Tx Nanocomposite Coatings with Assembled Eyelash-Like Microstructure Array: A New Approach for Effective Passive Anti-Icing and Active Photothermal Deicing.

To solve the problem of ice condensation and adhesion, it is urgent to develop new anti-icing and deicing technologies. This study presented the development of a highly efficient photothermal-enhanced superhydrophobic PDMS/Ni@Ti3C2Tx composite film (m-NMPA) fabricated cost-effectively and straightforwardly. This film was fabricated utilizing PDMS as a hydrophobic agent, adhesive, and surface protector, while Ni@Ti3C2Tx as a magnetic photothermal filler innovatively. Through a simple spraying method, the filler is guided by a strong magnetic field to self-assemble into an eyelash-like microstructure array. The unique structure not only imparts superhydrophobic properties to the surface but also constructs an efficient "light-capturing" architecture. Remarkably, the m-NMPA film demonstrates outstanding superhydrophobic passive anti-icing and efficient photothermal active deicing performance without the use of fluorinated chemicals. The micro-/nanostructure of the film forms a gas layer, significantly delaying the freezing time of water. Particularly under extreme cold conditions (-30 °C), the freezing time is extended by a factor of 7.3 compared to the bare substrate. Furthermore, under sunlight exposure, surface droplets do not freeze. The excellent photothermal performance is attributed to the firm anchoring of nickel particles on the MXene surface, facilitating effective "point-to-face" photothermal synergy. The eyelash-like microarray structure enhances light-capturing capability, resulting in a high light absorption rate of 98%. Furthermore, the microstructure aids in maintaining heat at the uppermost layer of the surface, maximizing the utilization of thermal energy for ice melting and frost thawing. Under solar irradiation, the m-NMPA film can rapidly melt approximately a 4 mm thick ice layer within 558 s and expel the melted water promptly, reducing the risk of secondary icing. Additionally, the ice adhesion force on the surface of the m-NMPA film is remarkably low, with an adhesion strength of approximately 4.7 kPa for a 1 × 1 cm2 ice column. After undergoing rigorous durability tests, including xenon lamp weathering test, pressure resistance test, repeated adhesive tape testing, xenon lamp irradiation, water drop impact testing, and repeated brushing with hydrochloric acid and particles, the film's surface structure and superhydrophobic performance have remained exceptional. The photothermal superhydrophobic passive anti-icing and active deicing technology in this work rely on sustainable solar energy for efficient heat generation. It presents broad prospects for practical applications with advantages such as simple processing method, environmental friendliness, outstanding anti-icing effects, and exceptional durability.

Moldable Tissue-Sealant Hydrogels Composed of In Situ Cross-Linkable Polyethylene Glycol via Thiol-Michael Addition and Carbomers.

Moldable tissue-sealant hydrogels were developed herein by combining the yield stress fluidity of a Carbomer and in situ cross-linking of 3-arm PEG-thiol (PEG-SH) and 4-arm PEG-acrylate (PEG-AC). The Carbomer was mixed with each PEG oligomer to form two aqueous precursors: Carbomer/PEG-SH and Carbomer/PEG-AC. The two hydrogel precursors exhibited sufficient yield stress (>100 Pa) to prevent dripping from their placement on the tissue surface. Moreover, these hydrogel precursors exhibited rapid restructuring when the shear strain was repeatedly changed. These rheological properties contribute to the moldability of these hydrogel precursors. After mixing these two precursors, they were converted from yield-stress fluids to chemically cross-linked hydrogels, Carbomer/PEG hydrogel, via thiol-Michael addition. The gelation time was 5.0 and 11.2 min at 37 and 25 °C, respectively. In addition, the Carbomer/PEG hydrogels exhibited higher cellular viability than the pure Carbomer. They also showed stable adhesiveness and burst pressure resistance to various tissues, such as the skin, stomach, colon, and cecum of pigs. The hydrogels showed excellent tissue sealing in a cecum ligation and puncture model in mice and improved the survival rate due to their tissue adhesiveness and biocompatibility. The Carbomer/PEG hydrogel is a potential biocompatible tissue sealant that surgeons can mold. It was revealed that the combination of in situ cross-linkable PEG oligomers and yield stress fluid such as Carbomer is effective for developing the moldable tissue sealant without dripping of its hydrogel precursors.

Effects of fuselage shape on helicopter aerodynamic performance in case of intermeshing-rotor interference

To study the influence of fuselage shape on the aerodynamic performance of a helicopter under the interference of an intermeshing-rotor, a numerical simulation method of flow field under the forward flight state of Synchropter is established based on the lattice Boltzmann method. Firstly, the Maryland helicopter was calculated to verify the scientific validity of the method. Then, the simplified S-97 fuselage was used as the object of analysis to analyze the aerodynamic data such as surface pressure, friction, and lift resistance of the fuselage with different head curvature, cross-section shapes, and transition segments under Synchropter interference with different attack angles in forward flight. The results show that increasing the radius of curvature of the nose can reduce the total drag of the fuselage; the fuselage with a circular cross-section shape has better aerodynamic characteristics of lift resistance, and the fuselage with rhombic cross-section shape has better transverse stability; the transition section with backward position, smaller upward dihedral angle, and smooth transition can avoid serious airflow separation and achieve the purpose of drag reduction.

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.

Similarity Solutions for Spherical Cavity Expansion in Strain-Softening Soils and its Application in Cone Penetration Test

The cavity expansion theory is commonly employed to predict the grouting pressure and cone penetration resistance. However, existing theoretical solutions for cohesive-frictional soils with dilation fail to simultaneously consider both the elastic deformation in the plastic zone and strain-softening behaviour of soils. To address this limitation, a similarity solution was derived for the expansion of spherical cavities from a zero initial radius with an initial confining pressure in strain-softening Mohr–Coulomb materials. The results demonstrate good agreement with previous theories, predicting an ultimate pressure higher than that obtained by neglecting elastic deformation in the plastic zone but lower than that calculated by neglecting softening characteristics. Moreover, several influential factors affecting the radius of the plastic zone and ultimate pressure were meticulously examined. On-site cone penetration test data and the theoretical results showed notable agreement. This indicates that the proposed solution exhibits a better conformance with the field data than do the previous solutions.

Analyzing mechanical properties and loading performance of polypropylene sandwich pipes

Sandwich pipes are widely used in various piping applications owing to their exceptional pressure resistance and thermal insulation properties. In this paper, the mechanical properties and loading performance of sandwich pipes made of polypropylene material have been investigated under different loading conditions including lateral and axial compression, as well as hydrostatic internal and external pressures. For this purpose, finite element models of sandwich pipes with various designs have been developed. Material properties have been determined through standard experimental tests, and the finite element models have been validated using lateral compression experiments. The results indicate that incorporating annular cores with thinner thickness and greater numbers, along with using a thicker inner pipe in the sandwich pipe structure, improves its properties and performance.

Synergistic Effects of Layered Double Hydroxide and MoS2 on the Performance of Lubricants

In this study, layered double hydroxide (LDH) and molybdenum disulfide (MoS2) were used as additives to prepare lubricants. The morphology and particle distribution of the LDH and MoS2 were characterized using a scanning electron microscope and a laser particle size analyzer, respectively. Thermogravimetric analysis was used to compare the performance of the lubricants at high temperature. The extreme pressure and wear resistance performance of the lubricants were tested using a four-ball machine and a fretting-wear machine. Then, the lubricants were applied in a bolt fastener. The loosening torque and surface wear condition at high temperature were compared. By adding LDH and MoS2 to the lubricants, the extreme pressure and wear resistance performance and anti-seize performance at high temperature were improved significantly. The LDH showed better anti-seize performance than the MoS2 because of its strong and stable structure at high temperature. The MoS2 showed better anti-wear performance under a high load because of its soft layered structure. The MoS2 with a larger particle size showed better extreme pressure performance under a high load. The LDH and MoS2 played a synergistic effect under the conditions of high temperature and high load.

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).

Behaviour of Steel Fiber Reinforced Concrete in Deep Beam for Flexure

Use of deep beam in construction field saves money as well as increase the strength of structure. Reinforced concrete deep beams have very useful structural application such as piles-caps, water tanks and tall buildings. Addition of steel fibers gives good results to both load carrying capacity and increase the flexural strength of the deep beam. Steel fiber is kind of newly developed reinforced material for concrete widely adopted globally now a day, which features good performance in anti-crack, pressure resistance, anti-abrasion bending toughness, affinity with concrete, reinforcement for construction element compjonent and lengthy service life. Thus by using the steel fiber reinforced deep beam with varying percentage of steel fibers increases the first crack load and the ultimate load which gives the high flexural strength to the structure and achieves economy. This paper includes study of behaviour of steel fiber reinforced concrete in deep beam with advantages, disadvantages, properties of steel fiber etc. Keywords: Steel Fiber, Beam, Anti-Abrasion Bending Toughness, Affinity, Reinforcement