Increase In Pressure Research Articles

Experimental study on the spray characteristics of high-pressure liquid ammonia under different ambient conditions

As a promising carbon-free fuel, ammonia is expected to be widely applied in internal combustion engines. However, the physical properties of ammonia are quite different from those of conventional fuels, which leads to different spray characteristics. In this paper, the ammonia spray under injection pressure as high as 80 MPa was visualized by the diffused back-illumination imaging method, and the liquid ammonia spray characteristics under different ambient pressures and ambient temperatures were analyzed. The liquid spray penetration length, cone angle and tip velocity calculated from the spray images provide a reference database for numerical simulation. The results show that the development characteristics of liquid ammonia spray are significantly different under flare flash boiling, transitional flash boiling and non-flash boiling conditions. Flash boiling (especially flare flash boiling) inhibits the initial liquid spray penetration. The spray tip velocity increases first and then gradually decreases under flash boiling conditions. Ammonia spray has obvious radial expansion at the initial stage of flare flash boiling and the spray contour under flare flash boiling conditions is noticeably distorted, forming an obvious dilute region. With the increase of ambient pressure, the intensity of flash boiling reduces, the dilute region gradually disappears, and the distortion of the spray contour gradually weakens. Under non-flash boiling conditions, ammonia spray presents a dense and regular shape; there is no spray acceleration but a sharp decrease in spray tip velocity at the initial stage, and then the spray penetrates forward at a similar velocity. The spray penetration velocity decreases significantly with the increase of ambient pressure. The increase in ambient temperature accelerates the vaporization of ammonia spray. The liquid spray penetration length decreases and maintains with only slight fluctuations during the injection process as the ambient temperature increases from 300 K to 600 K because the vaporization rate and penetration velocity reach a balance.

DFT study of structural, electronic, optical and elastic properties of lead-free Bi based perovskites X2NaBiCl6 (X= K and Rb) with pressure

The pressure dependent structural, electronic, optical and mechanical properties of Bi-based cubic halide double perovskites, X2NaBiCl6 (X = K and Rb) are explored by implementing full-potential linearized augmented plane wave (FP-LAPW) method. At zero pressure, K2NaBiCl6 and Rb2NaBiCl6 posses indirect band gaps of 3.746 and 3.735eV, respectively and the band gaps decrease with increasing pressure for both compounds. The elliptical shape of charge density contours under high pressure ensured a strong covalent bonding between K/Rb and Cl atoms along (110) plane. We explored the essential optical properties for both compounds with different pressures and found a red-shift with increase in pressure. Furthermore, all the values of mechanical parameters, viz. elastic constants and moduli, Vickers hardness, Debye and melting temperatures are enhanced with increasing pressure. Due to suitable band gaps and appropriate mechanical parameters, both perovskites are proved as promising candidates in thermoelectric power generation and high temperature devices.

Exploring the Impact of Elevated Pressure on the Structural Dynamics of TlInS2 Crystal (I): A First-Principles Investigation with XRD, Raman, and Hirshfeld Topology

The structural dynamics of Thallium Indium Disulfide (TlInS2) crystal under elevated pressures were comprehensively investigated using a combination of X-ray diffraction (XRD), Raman spectroscopy via first-principles calculations, and Hirshfeld surface (HS) analysis. This study aims to elucidate pressure-induced modifications in the crystal structure and their associated properties of TlInS2 crystal. The findings reveal significant structural transformations as pressure increases, with XRD patterns indicating lattice compression and a critical transition from semiconductor to conductor at pressure P=6.25GPa [42]. The calculations predict a reduction in bond lengths, specifically S1-In1 and S1-Tl2, alongside a corresponding decrease in lattice parameters and unit cell volume. Raman spectroscopy corroborates these changes through shifts in phonon modes. The HS analysis provides further insights into pressure-dependent alterations in intermolecular interactions, revealing changes in voids and surface characteristics. The data gained from TlInS2's structural behavior under pressure, contributing to the optimization of its functional properties for pressure-tunable applications in high-performance electronic and optoelectronic devices.

Surgeon experience affects perioperative pain in cats undergoing elective ovariohysterectomy: a randomized clinical trial.

This study aimed to compare the outcomes between surgeries performed by either experienced or inexperienced surgeons by assessing intraoperative nociception and perioperative analgesia. 16 healthy, client-owned female cats were randomly allocated into 2 groups of 8: one undergoing surgery by an experienced surgeon (GES group) and the other by inexperienced surgeons (GIS group). Both groups received IM premedication with acepromazine (0.05 mg/kg) and methadone (0.3 mg/kg). After 20 minutes, venipuncture and induction with propofol (dose-response, IV) were performed. Maintenance was achieved with inhaled isoflurane. Intraoperative vital parameters were monitored, and fentanyl (2.5 µg/kg, IV) was administered as rescue analgesia when needed. Postoperatively, pain was assessed with a visual analog scale and the multidimensional pain scale of the Universidade Estadual Paulista in Botucatu; morphine (0.2 mg/kg, IM) was used for rescue analgesia, as necessary. In the GIS group, significant increases in heart rate and systolic blood pressure were noted during surgery, especially during pedicle clamping. Respiratory rate and end-tidal isoflurane levels were higher in the GIS group at specific surgical stages. Survival analysis indicated that the GIS group had a greater need for fentanyl. Postoperative pain scores were generally low, but a higher proportion of GIS cats required rescue analgesia. Surgeon experience influences intraoperative parameters and fentanyl consumption. Inexperienced surgeons contribute to increased postoperative pain and poorer wound healing outcomes in cats undergoing elective ovariohysterectomy. Ovariohysterectomy is a common procedure in veterinary practice, and surgical expertise significantly impacts pain management and recovery. Yet, its effects have been underexplored, potentially compromising animal welfare.

Evaluation of CO2 Leakage Potential through Fault Instability in CO2 Geological Sequestration by Coupled THMC Modelling

A faulted saline aquifer system was simulated in a coupled thermal-hydraulic-mechanical-chemical (THMC) framework to examine the potential breaching of the caprock seal from long-term CO2 sequestration. The pH of the brines steadily dropped from 7.5 to 4.7 due to the continuous injection of scCO2 (supercritical CO2), which was caused by the rapid dissolution of calcite in the reservoir and associated fault zones, alongside alterations in the concentrations of primary and secondary minerals within the formation. The increase in pore pressure with the continuous injection of scCO2 triggered fault reactivation at 6y with the resultant leakage of CO2 along the fault. This builds CO2 saturation inside the fault at 7y to six-fold higher than pre-slip. Continuing shear reactivation and creation of reactive surface area following the initial CO2 leakage accelerates dissolution/precipitation reactions, in turn further increasing porosity and permeability of the reservoir and fault. In particular, the permeability and porosity in the fault zone were increased by only 2% and 6%, respectively – staunched by competitive feedbacks in dissolution countered by precipitation that are individually much larger. Comparison of mineral concentrations adjacent to the fault before-and-after instability revealed that the development of shear failure also promotes the transport of reactivated minerals into the fault zone. Among them, feldspar changes most significantly in later stages, dominated by dissolution with the volume fraction decreasing by 80% and increasing the aqueous concentration of K+ by approximately an order of magnitude. However, secondary minerals counter this dissolution through precipitation with the volume fraction of kaolinite increasing by an order of magnitude compared with the original fraction. Finally, the evolution of the fault sealing coefficient (FS) demonstrates that the porosity and permeability exert a pivotal influence in controlling the self-sealing behavior in the basal of the fault, while the upper fault layer exhibits self-enhancing response. A notable observation is that changes in mineral ion concentrations in fault zones could be applied as a significant diagnostic signal to monitor fault stability and the potential for progress of self-sealing behavior.

Numerical Study of the Spontaneous Ignition Mechanisms of Pressurized Hydrogen Released Inside Pipes with Different Structures

Hydrogen is considered a key clean energy carrier to achieve the global goal of carbon neutrality. But spontaneous ignition can occur when pressurized hydrogen is released into pipes, and the presence of different pipe structures will significantly affect the ignition mechanism. In this work, the effects of varied pipe structures on the shock wave propagation and spontaneous ignition characteristics are investigated by numerical simulation with the DNS-like approach, EDC combustion model, and 21-step detailed hydrogen combustion mechanism. Results show that the simulation is in well agreement with the experimental data. Five dominant spontaneous ignition mechanisms are provided depending on different pipe structures. Among all types of pipe structures investigated, contraction structures can lead to a greater increase in shock wave pressure due to more severe shock wave reflection and convergence. While enlargement structures can contribute to more mixing of hydrogen and air, causing more sufficient combustion. This study provides a comprehensive understanding and clear safety guidance to inform the practical application of hydrogen energy.

Enhanced Quantum Efficiency via Co-Substitution in Red-Emitting Phosphor Sr2[MgAl5N7] : Eu2+ for Advanced Spectroscopic Applications Including Laser Displays with Ultra-High Luminescence Saturation Threshold.

In order to obtain novel and more efficient red light-emitting materials, a series of Sr2[Mg1-xLixAl5-xSixN7] : 0.01Eu2+ (SMAN-xLS, 0≤x≤0.5) red phosphors were devised and successfully synthesized via the high temperature solid state reaction and the effects of the co-substitution of [Mg-Al]5+ by [Li-Si]5+ on structural and luminescence properties is investigated in detail. A series of powder XRD data and Rietveld refinement indicate that [Li-Si]5+ co-substitution can successfully enter the Sr2[MgAl5N7] : 0.01Eu2+ (SMAN) lattice. With the entry of [Li-Si]5+ into the lattice, the substitution of Al3+ by Si4+ leads to the weakening of the nephelauxetic effect of the 5d level of Eu2+, which shifts the emission peak from 657 nm to 647 nm and reduces the excitation in the green region, i.e., lowers the absorption of green light. When the amount of [Li-Si]5+ co-substitution is x=0.1, the luminescence intensity and thermal stability of the sample are enhanced, in which the external quantum efficiency (EQE), reflecting the luminescence intensity, is elevated by 49.6 %. The increase in lattice rigidity gives rise to higher luminescence intensity, and the introduced trap levels for the compensation of luminescence enhances the thermal stability. Under blue laser excitation, the SMAN-0.1LS can achieve an ultra-high luminescence saturation threshold of 52.22 W/mm2, which is remarkably superior to other existing red phosphors, a breakthrough performance that has enormous potential for application in high-power laser display light sources. Cathodoluminescence (CL) characterization and measurements attest to the favorable CL properties of SMAN-0.1LS. By measuring the pressure-dependent luminescence of SMAN-0.1LS, the emission peak can be shifted from 650 nm to 702 nm with the increase of pressure, and the sensitivity dλ/dP is 5.07 nm/GPa, which is indicative of the potential application of this system as an optical pressure sensor.

Enhanced Quantum Efficiency via Co‐Substitution in Red‐Emitting Phosphor Sr2[MgAl5N7] : Eu2+ for Advanced Spectroscopic Applications Including Laser Displays with Ultra‐High Luminescence Saturation Threshold

AbstractIn order to obtain novel and more efficient red light‐emitting materials, a series of Sr2[Mg1−xLixAl5−xSixN7] : 0.01Eu2+ (SMAN‐xLS, 0≤x≤0.5) red phosphors were devised and successfully synthesized via the high temperature solid state reaction and the effects of the co‐substitution of [Mg−Al]5+ by [Li−Si]5+ on structural and luminescence properties is investigated in detail. A series of powder XRD data and Rietveld refinement indicate that [Li−Si]5+ co‐substitution can successfully enter the Sr2[MgAl5N7] : 0.01Eu2+ (SMAN) lattice. With the entry of [Li−Si]5+ into the lattice, the substitution of Al3+ by Si4+ leads to the weakening of the nephelauxetic effect of the 5d level of Eu2+, which shifts the emission peak from 657 nm to 647 nm and reduces the excitation in the green region, i.e., lowers the absorption of green light. When the amount of [Li−Si]5+ co‐substitution is x=0.1, the luminescence intensity and thermal stability of the sample are enhanced, in which the external quantum efficiency (EQE), reflecting the luminescence intensity, is elevated by 49.6 %. The increase in lattice rigidity gives rise to higher luminescence intensity, and the introduced trap levels for the compensation of luminescence enhances the thermal stability. Under blue laser excitation, the SMAN‐0.1LS can achieve an ultra‐high luminescence saturation threshold of 52.22 W/mm2, which is remarkably superior to other existing red phosphors, a breakthrough performance that has enormous potential for application in high‐power laser display light sources. Cathodoluminescence (CL) characterization and measurements attest to the favorable CL properties of SMAN‐0.1LS. By measuring the pressure‐dependent luminescence of SMAN‐0.1LS, the emission peak can be shifted from 650 nm to 702 nm with the increase of pressure, and the sensitivity dλ/dP is 5.07 nm/GPa, which is indicative of the potential application of this system as an optical pressure sensor.

Analysis of Pressure Drop in Gas–Solids Cyclone Separators: An Experimental Approach

In industrial operations, cyclone separators are essential for removing particles from gas streams. The performance and energy efficiency of these devices are greatly impacted by the pressure drop across them. Through experimental investigation, this paper examines the pressure decrease in gas-solids cyclone separators. The effect of many operational factors on the pressure drop was investigated, including gas velocity, particle size, and input design.The findings demonstrated that the pressure drop across the cyclone increases significantly with increasing inflow velocity and reduces with increasing cyclone size. Regardless of cyclone size, input velocity, or particle size, a strong direct correlation was found between the pressure drop for dusty air and that for clean air. Operating at moderate gas velocities was shown to significantly reduce pressure drop without compromising separation performance, whereas higher velocities necessitate advanced cyclone designs or secondary systems to mitigate the associated pressure increases

Phase transition and metallization of semiconductor GeSe at high pressure

Over the past few decades, semiconductor materials of the group IV-VI monochalcogenides have attracted considerable interest from researchers due to their rich structural characteristics and excellent physical properties. Among them, GeS, GeSe, SnS, and SnSe crystallize in an orthorhombic structure (Pbnm) at ambient conditions. It has been reported that GeS, SnS, and SnSe transform into a higher symmetry orthorhombic structure (Cmcm) at high pressure, while the phase transformation route of GeSe at high pressure remains controversial. As an IV-VI monochalcogenide, GeSe possesses excellent application prospects and has been extensively studied in the fields of optoelectronic and thermoelectric. Here we systematically investigate the structural behavior, optical and electrical properties of GeSe at high pressure. GeSe undergoes a phase transition from thePbnmtoCmcmphase at 33.5 GPa, like isostructural GeS, SnS, and SnSe. The optical bandgap of GeSe decreases gradually as pressure increases and undergoes a semiconducting to metallic transition above 12 GPa. This study exhibits a high-pressure strategy for modulating structural behavior, optical and electrical properties of the group IV-VI monochalcogenides to expand its prospects in optoelectronic and thermoelectric properties.

Research on Microgrid Optimal Scheduling Based on an Improved Honey Badger Algorithm

As global energy demands continue to grow and environmental protection pressures increase, microgrids have garnered widespread attention due to their ability to effectively integrate distributed energy sources, improve energy utilization efficiency, and enhance grid stability. Due to the complexity of internal structure, variety of energy sources, and uncertainty of load demand, the optimal scheduling problem of microgrids becomes extremely complicated. Traditional optimization methods often perform poorly in complex and dynamic microgrid environments, and it is assumed that the complexity is low or that more simplification is needed, which leads to poor convergence and local optimality when dealing with uncertainty and nonlinear problems, making intelligent optimization algorithms a crucial solution to this problem. To address the shortcomings of the traditional honey badger algorithm, such as the slow convergence speed and a tendency to fall into local optima in complex microgrid optimal scheduling problems, this paper proposes a multi-strategy improved honey badger algorithm. During the population initialization phase, a combined opposition-based learning strategy is introduced to enhance the algorithm’s exploration and exploitation capabilities. Additionally, the introduction of variable spiral factors and a linearly decreasing strategy for parameters improves the overall efficiency of the algorithm and reduces the risk of local optima. To further enhance population diversity, a hunger search strategy is employed, providing stronger adaptability and global search capabilities in varying environments. The improved honey badger algorithm is then applied to solve the multi-objective optimal scheduling problem in grid-connected microgrid modes. The simulation results indicate that the improved honey badger algorithm effectively enhances the economic and environmental benefits of microgrid operations, improving system operational stability.

Comparison of High and Low Dose Calcium Supplementation in Prevention of Hypertensive Disorders of Pregnancy

Calcium supplementation during pregnancy may prevent high blood pressure and preterm labour. Out of 500 women, 480 completed the study. At hospital enrolment, the average systolic blood pressure (SBP) was similar between the two groups (116.10 mm Hg vs. 115.01 mm Hg; P = 0.215), as was the average diastolic blood pressure (DBP) (72.74 mm Hg vs. 72.12 mm Hg; P = 0.301). No significant increase in blood pressure was observed in the majority of pregnant women in either group until delivery. Only 2.5% of women in the low-dose group (LDG - group I) and 1.88% in the high-dose group (HDG - group II) developed pre-eclampsia by the end of the study, with no significant association between different calcium dosages and the occurrence of pre-eclampsia (P = 0.503). Regarding maternal complications, 0.63% of women in the group I and 0.21% in the group II experienced major complications during pregnancy or postpartum, but this was not statistically significant (P = 0.623). Among the 480 women, 475 had term labor, and only 5 had preterm deliveries (before 36 weeks of gestation). No maternal deaths were reported.Our study concluded that calcium supplementation, whether in low or high dose, provides significant benefit for pregnant women. The findings demonstrate a notable advantage in preventing pregnancy-induced hypertension (PIH), preterm labor, premature births, and related complications. Therefore, calcium supplementation is highly effective in preventing PIH, which in turn helps prevent pre-eclampsia and eclampsia. As both low and high dose Calcium are effective in preventing PE and Eclampsia, it may be recommended that low dose calcium supplementation may be helpful in prevention of HDP and have favourable feto-maternal outcome in a low resource setting like ours. Keywords: Hypertensive disorders of pregnancy (HDP), Blood Pressure, Pre-eclampsia, Calcium.

Pressure-induced structural stability, metallization and optoelectronic properties of transition metal chalcogenide BaTiS3

The pressure effects on the structural stability, metallization and optoelectronic properties of transition metal chalcogenide BaTiS3 are investigated by performing ab-initio calculations. Our calculations show that BaTiS3 has a hexagonal structure at ambient pressure, which matches well with the available experimental values. As pressure increases, a transition from hexagonal to orthorhombic phase occurs at around 10.8 GPa. The band structure and density of states of hexagonal BaTiS3 have been calculated and analysed. Moreover, the effect of pressure on the optical properties has been studied in terms of dielectric function as well as absorption coefficient, reflectivity and extinction coefficient. The application of hydrostatic pressure has shifted the maximum absorption toward the visible range, revealing that hexagonal BaTiS3 can be used for high pressure optoelectronic applications.

Composition of the Low Molecular Weight Metabolome of Potamogeton perfoliatus (Potamogetonaceae) as an Indicator of the Transformation of the Ecological State of the Littoral Zone

The composition and nature of changes in the low-molecular-weight metabolome (NM) of Potamogeton perfoliatus L., growing in 6 biotopes of Lake Ladoga with different types of the anthropogenic load has been analyzed. According to the research results, it was found that the total number of low molecular weight organic compounds (LMWOCs) in the P. perfoliatus NM composition is directly dependent on anthropogenic load, which is well marked by the development of cyanobacteria. The greater the intensity of pollution or eutrophication of waters, or the higher the number of cyanobacteria, the lower the total number of LMWOCs and their concentration. A strongly pronounced dependence of the total concentrations of groups of NM compounds on the anthropogenic disturbance of the biotope and the concentration of cyanobacteria was revealed. A decrease in the number, relative amount, total concentration of carboxylic acids, number and content of unsaturated fatty acids, and, at the same time, an increase in the composition and content of phenols and the total content of aldehydes and ketones depends on an increase in anthropogenic pressure. The specific composition of NM of pierced pondweed depends on its response to biotic and abiotic factors of the aquatic environment, including anthropogenic ones. The revealed features of the change in the composition of P. perfoliatus NM make it possible to use it as an integral indicator of the anthropogenic impact on the littoral biotopes of water bodies and the deterioration of their ecological state.

Developing an accurate finite element model for brake disc in contact with the pad using experimental modal analysis

The brake system is a critical safety component in cars, and its performance is essential for the safety of both the driver and passengers. The stability of the brake disc and understanding the contact area between the disc and the brake pads are crucial aspects of brake system design and performance. This paper aims to create an accurate model of the brake system, especially the contact area between the disc and the pads. This model can be used to investigate the effects of increasing braking pressure and changing the contact surface. Moreover, this model can calculate the dynamic responses of the system when an angular velocity is applied to the disc. First, a braking system was tested experimentally several times. Then a finite element model of the structure was created in ANSYS commercial software with defining suitable elements for the contact area between the disc and the pads. In the following, by an identification process a distribution of contact parameters at different braking pressures was obtained. The results shows that when the braking pressure increases, the dynamic responses of the structure increase, as well as the contact stiffness. A further increase in braking pressure does not have much effect on the contact stiffness and the contact area becomes like a new support.

Propagation and distribution of shear and tensile hydraulic fractures affected by frictional coal beddings.

As a typical sedimentary rock, coal seams are usually rich in bedding planes, which significantly affect the propagation process of hydraulic fracture (HF) network and reservoir permeability. In this study, the profile characteristics and the bedding roughness of the coal seam at depth of 2800m from Daniudi Gas Field in China is investigated. The failure mechanism of shear-expansion effect under low pressure and dynamic shear under high pressure of coal beddings induced by the dissolution-corrosion effect of fracturing liquid is analyzed. The development process of HF network under different bedding angles, joint roughness coefficients (JRCs), stress differences, and confining pressures is numerically simulated by cohesive element method. Results show that the JRC of coal beddings has significant effects on the morphology of HF networks. When the JRC exceeds 15, a HF network structure with tensile main fractures and shear secondary cracks is developed. The shear fractures account for a considerable proportion (33-66%) multi-layer layered coal seams and should be taken seriously during reservoir reconstruction. As confining pressure increases, the total length of tensile HFs sharply decreases, while the change in the total length of shear HFs is not significant. When the confining pressure increases from 5 to 15MPa, the length ratio of shear HFs to tensile hydraulic fractures increases from 0.36 to about 1, confirming that increasing confining pressure can promote the transformation of HF failure types from tension to shear. The ratio of secondary crack to main crack length is between 6.31 and 9.78, indicating the secondary fractures occupy an absolute proportion in the hydraulic fracture network. This study is of significance for understanding the hydraulic fracture network development in coal reservoirs.

Abstract 4137364: Sex differences in the right ventricle in the Sugen-Hypoxia rat model of pulmonary arterial hypertension

Background: An unexplained estrogen puzzle exists in pulmonary arterial hypertension (PAH): PAH occurs ~4 fold more frequently in women than men; however, women with PAH have better right ventricular (RV) function and survival than the men. Sex differences and the associated mechanism in RV in PAH are not well understood. Aim: To characterize sex differences in RV function and structure in PAH. Methods: Sprague-Dawley rats were injected with Sugen (SU5416, 25mg/kg), and subjected to 3 weeks of hypoxia, followed by 5 weeks of normoxia. Control rats received vehicle and stayed in normoxia for up to 8 weeks. RV pressure-volume, mitochondrial properties, weight, myocyte size, cell proliferation, and interstitial and perivascular (right coronary arteries, RCA) fibrosis were obtained. Results: Sugen-Hypoxia (SuHx) caused significant increases in RV systolic pressure (RVSP) and effective arterial elastance (Ea) in both sexes (P<0.05), but caused slightly greater increase in RV end-systolic elastance (Ees) in females vs males, leading to a preserved RV-pulmonary artery coupling (Ees/Ea) in females and a significant decrease in Ees/Ea in males (P<0.05). SuHx caused a significant increase in RV diastolic pressure only in males (P<0.05), which is associated with significantly higher amount of RV interstitial fibrosis in males vs females. In addition, SuHx caused significant increase in cell proliferation in both sexes (P<0.05) though with slightly greater in crease in males, which is well correlated with RV interstitial fibrosis. Whilst there was no sex difference in RV hypertrophy in SuHx rats as indicated by both fulton index and myocyte size, female RV had smaller myocytes than males at baseline, indicating a greater increase in myocyte size in response to SuHx. Finally, there was a significant increase in RCA fibrosis in male SuHx rats (P<0.05) but not in females, potentially leading to a greater degree of ischemia in male SuHx RV, and this is consistent with impaired mitochondrial properties (decreased mitochondrial fusion, membrane potential an superoxide) in male SuHx rat RV (P<0.05) but preserved mitochoindrial properties in females. Conclusions: SuHx resulted in similar level of RV afterload in both sexes, but compared to males, RV in females responded differently in both function (Ees and mitochondrial properties) and structure (myocyte size and fibrosis). Future studies on the associated mechanism are needed to gain therapeutic insight for RV in PAH.

Experimental and analytical assessment of the bending behaviour of floating inflated membrane beams

The study aims to study the bending and failure behaviour of the inflated membrane beams under floating conditions to support their application in floating platforms. Bending tests are conducted to assess the structural stiffness and ultimate bearing capacity of the beam with various diameters and inflated pressures. With the elastic modulus determined through four-point bending tests, a new analytical formula based on Winkler elastic foundation theory is then developed to predict the deflection of the beams. The results revealed that the beams initially undergo total submersion, followed by end turn-up and anti-arching deformation in the loaded section. The bearing capacity of the beams increases with the increase in internal pressure and diameter. Localised wrinkling is a typical failure mode at low internal pressures, while at high pressures, the failure mode shifts to boundary failure, characterised by submerging in water. The experimental and analytical results show quite good agreement, confirming the accuracy of the current analysis. Overall, this paper contributes to understanding the bending and failure behaviour of inflated membrane beams under floating conditions and supports the offshore structure safety design.

Response of the nephron arterial network and its interactions to acute hypertension: a simulation.

We simulated the dynamics of a group of 10 nephrons supplied from an arterial network and subjected to acute increases in blood pressure. Arterial lengths and topology were based on measurements of a vascular cast. The model builds on a previous version exercised at a single blood pressure with 2 additional features: pressure diuresis and the effect of blood pressure on efferent arteriolar vascular resistance. The new version simulates autoregulation, and reproduces tubule pressure oscillations. Individual nephron dynamics depended on mean arterial pressure and the axial pressure gradient required to cause blood flow through the arteries. Rhythmic blood withdrawal into afferent arterioles caused blood flow fluctuations in downstream vessels. Blood pressure dependent changes in nephron dynamics affected synchronization metrics. The combination of vascular pressure gradients and oscillations created a range of arterial pressures at the origins of the 10 afferent arterioles. Because arterial blood pressure in conscious animals has 1/f dynamics, we applied an arterial pressure pattern with such dynamics to the model. Amplitude of tubule pressure oscillations were affected by the 1/f blood pressure fluctuations, but the oscillation frequencies did not change. The pressure gradients required to deliver blood to all afferent arterioles impose a complexity that affects nephrons according to their locations in the network, but other interactions compensate to ensure the stability of the system. The sensitivity of nephron response to location on the network, and the constancy of the tubular oscillation frequency provide a spatial and time context.

Abstract 4133846: Even Mild Increase in Pulmonary Arterial Pressure Following Kidney Transplantation is Associated with Increased Mortality

Background: In end-stage renal disease (ESRD), elevated systolic pulmonary artery pressure (sPAP) is common, attributed to post-capillary pulmonary hypertension (PH) and associated with adverse outcomes. Kidney transplantation (KT) may mitigate ESRD-PH. We aimed to profile sPAP trajectory in a national cohort of ESRD patients pre- and post-KT, and link findings to clinical outcome. Methods: We analyzed retrospectively all patients within the Veterans Affairs Healthcare System undergoing KT between 2000-2019 with sPAP recorded pre- and post-KT by echocardiography. PH was defined by >35mmHg. Patients were assigned to one of the following groups: Never PH, New PH post-KT, Resolved PH post-KT, and Persistent PH. Spline curve and Kaplan-Meier analyses were used to test the association of sPAP or PH group with all-cause mortality, adjusted for age and sex. Results: From 631 patients (median 62 [IQR 58-65]yr; 97% male), there were 231 (36.6%), 184 (29.2%), 133 (21.1%), and 83 (13.1%) patients in the Persistent PH, Never PH, Resolved PH, and New PH groups, respectively. Never PH, Resolved PH and New PH had, overall, similar cardiopulmonary comorbidities ( Tab. 1 ). By contrast, Persistent PH had the highest rate of congestive heart failure, atrial fibrillation, and impaired diastolic relaxation assessed by E/E’. Creatinine post-KT, indicative for graft function, was stable in Never PH, Resolved PH and Persistent PH, but significantly increased in New PH. Of all groups, Resolved PH was associated with the most favorable survival rate (HR 0.73 [95%CI 0.51-1.05], p=0.087). New PH and Persistent PH were associated with a 51% (HR=1.51 [95%CI 1.06-2.15], p=0.023) and 37% (HR=1.37 [95%CI 1.03-1.82], p=0.029; referent group for all: Never PH) increase in adjusted mortality risk post-KT ( Fig. 1a ). Overall, we observed 21% (HR=1.21 [95%CI 1.11-1.31], p<0.001) increase in mortality hazard adjusted for age, sex and baseline sPAP, per 10mmHg increment increase in sPAP from pre-KT to post-KT whereas a 10mmHg sPAP decrease was associated a 17% decrease in mortality (HR=0.83 [95%CI 0.76-0.90], p<0.001) ( Fig. 1b ). Conclusion: These data suggest that PH is common post-KT and includes a sizeable group of patients without PH pre-KT. Increased PAP or failure for PH to resolve post-KT were independently associated with mortality. Overall, these data warrant prospective studies in sex-balanced cohorts that use PH to stratify KT candidacy and PAP as a longitudinal biomarker of graft function post-KT.