Low Pressure Research Articles

Incidence and predictors of radial artery occlusion following transradial coronary procedures

Abstract Background Transradial access for percutaneous coronary procedures has grown in popularity because of its advantages over the femoral approach. However, the benefit is overshadowed by an increased rate of radial artery occlusion (RAO). We aim to assess incidence and predictors of RAO after transradial catheterization. The anatomic variations of the radial artery (RA) were also studied. Methods This prospective study enrolled 427 patients who underwent coronary angiography or angioplasty via transradial access. An ultrasound evaluation of forearm arteries was performed. In case of RAO, another ultrasound check-up was performed after 1 month and 3 months of the procedure. Results Our study population includes 288 patients (32.6% female). The mean age was 61.9 ± 11.1 years. RAO occured in 48 patients (11.24%), among whom spontaneous recanalization was observed within 3 months in 15 patients (32.6%). On multivariate analysis, a younger age (OR 0.642 [CI 95%: 0.480 – 0.858], P = 0.031), low periprocedural systolic blood pressure, (OR 0.598 [CI 95%: 0.415 – 0.862], P = 0.007), a small radial diameter (OR 0.371 [CI 95%: 0.323 – 0.618], P = 0.031), insufficient anticoagulation (OR 0.287 [CI 95%: 0.163 – 0.505], P < 0.001), occlusive hemostasis (OR 0.128 [CI 95%: 0.047 – 0.353], P < 0.001), and a long duration of hemostasis emerged as independent predictors of radial occlusion. The overall incidence of radial artery anatomic variations was 14,8% (n=63). Among these patients, 40 (63.5%) had a high radial origin, 18 (28.6%) had extreme radial artery tortuosity, and 5 (7.9%) had a full radioulnar loop. Conclusion The incidence and prevalence of radial artery occlusion is expected to increase. Insufficient heparinization and occlusive hemostasis are the main modifiable predictors. The preventive strategy should focus primarily on these 2 predictive factors.

Effect of pre-procedural blood pressure on one-year cardiovascular events after percutaneous coronary intervention in patients with acute myocardial infarction

Abstract Background Although high systolic blood pressure (SBP) and low diastolic blood pressure (DBP) are associated with adverse cardiovascular outcomes in coronary artery disease, their impact on patients with acute myocardial infarction (AMI) remains unclear. Methods This multicenter prospective study included 874 AMI patients undergoing percutaneous coronary intervention (PCI) with pre-procedural blood pressure recorded. Patients with cardiogenic shock and missing blood pressure data were excluded. The patients were categorized based on SBP (high ≥120 mmHg, low <120 mmHg) and DBP (high ≥70, low <70 mmHg) into four groups: high SBP and high DBP (HSHD), high SBP and low DBP (HSLD), low SBP and high DBP (LSHD), and low SBP and low DBP (LSLD) group. The primary endpoint was a composite of all-cause mortality, myocardial infarction, stroke, and major bleeding. Results The average age of the patients was 68.9 years, with a mean pulse pressure of 58 ± 19 mmHg. The Kaplan-Meier curves showed significant differences in the primary endpoints among the four groups (Log-rank test, p <0.001). At 12 months, the primary endpoint occurrence was highest in the HSLD group (13.3%) and lowest in the LSHD group (2.4%). Additionally, multivariate Cox regression analysis revealed that the HSLD group, compared to the HSHD group, was independently correlated with an increased risk of cardiovascular events (hazard ratio 2.43, 95% confidence interval 1.16-5.11; p = 0.019). Conclusion Pre-procedural HSLD serves as an independent predictor and is associated with one-year adverse cardiovascular outcomes in AMI patients.Patient diagramKaplan-Meier one-year outcome

The effects of SGLT2 inhibitors on right ventricle functions in heart failure patients: update meta-analysis of the current literature

Abstract Background There is some discrepancy in the present studies concerning the effect of sodium-glucose cotransporter type 2 (SGLT2) inhibitors on right ventricular (RV) functions in heart failure (HF) patients. The current meta-analysis was focused on determining the impact of SGLT2 inhibitors on RV functions in such individuals. Methods Two independent investigators searched PubMed, Google Scholar, and the Cochrane Library for articles of interest. To analyze heterogeneity, Higgins' I2 as well as prediction intervals and Egger's test were utilized to assess heterogeneity. The Newcastle-Ottawa standard ratings approach was used to assess the quality of observational studies. The Robin-I risk of bias algorithm was used to assess the bias risks of randomized studies. Results This meta-analysis evaluated 8 studies in total. Over the follow-up time frame, patients who used SGLT-2 inhibitors had substantially lower systolic pulmonary artery pressure (sPAP) and higher TAPSE values (mean difference (MD) = 1.30 [0.78;1.82], p =0.002 and MD =-5.39 [-7.88; -2.89], p=0.003, respectively). There was no significant difference in RVS’ values between follow-up and baseline (MD=1.38 [-1.35;3.80], p=0.169). However, as compared to the baseline period, fractional area contraction (FAC) values were substantially larger at the end of the follow-up period (MD=5.40 [3.74;7.07], p=0.015). Conclusion To the best of our knowledge, this is the first meta-analysis assessing the impact of SGLT2 inhibitors on RV function in HF patients. Our findings suggest that SGLT2 inhibitors may improve RV performance in HF patients.

Tongue Pressure and Grip Strength as Indicators of Persistent Dysphagia After Acute Stroke.

This study aimed to identify the independent predictors of postacute stroke dysphagia at discharge using sarcopenia-related parameters. This single-center prospective observational study assessed consecutive inpatients diagnosed with cerebral infarction or cerebral hemorrhage upon admission to the stroke unit. Tongue pressure, grip strength, and body composition were evaluated within 48h. Dysphagia was defined by a functional oral intake scale of ≤ 5. Patient characteristics were compared between non-dysphagia and dysphagia groups using Mann-Whitney or chi-squared tests. Logistic regression analysis was performed using age, sex, tongue pressure, grip strength, skeletal muscle mass index (SMI), and National Institutes of Health Stroke Scale (NIHSS) scores as explanatory variables, with dysphagia at discharge as the objective variable. A total of 302 patients (mean age: 69.4 ± 13.8 years, 67.5% male) were analyzed, with 64 having dysphagia at discharge (21.2%). The dysphagia group was significantly older (p<0.001), had higher NIHSS scores on admission (p<0.001), lower SMI (p = 0.002), lower grip strength (p<0.001), and lower tongue pressure (p<0.001) than the non-dysphagia group. Logistic regression revealed that age (OR: 1.042, p = 0.018), tongue pressure (OR: 0.954, p = 0.010), and grip strength (OR: 0.943, p = 0.048) on admission were independent predictors of dysphagia at discharge, while NIHSS scores (OR: 1.403, p = 0.106), sex, and SMI (OR: 1.403, p = 0.150) were not. Older age, reduced tongue pressure, and reduced grip strength are strong predictors of persistent poststroke dysphagia at discharge. Thus, muscle strength is a more valuable parameter than muscle mass in predicting persistent poststroke dysphagia.

Timing of inopressor initiation in patients with acute myocardial infarction complicated by cardiogenic shock

Abstract Introduction Inotropes and vasopressors (inopressors) are commonly used in the treatment of acute myocardial infarction complicated by cardiogenic shock (AMICS). The characteristics of patients subjected to early or late initiation of inopressors are not yet described, and the impact of timing on outcomes remains uncertain. Purpose This retrospective real-world data study aims to identify patient-, treatment-, and outcome characteristics of AMICS patients treated with early- or late initiated inopressors. Methods The Netherlands Heart Registration (NHR) prospectively records baseline, procedural, and outcome data for PCI patients. Between 2017-2021, additional retrospective data on CS patients were collected by fourteen Dutch hospitals. Patients were categorized based on the timing of inopressor initiation, either early (pre PCI) or solely late (at the cathlab or within 24 hours after PCI). Patients presenting with an out of hospital cardiac arrest were excluded. Missing data were imputed through multiple imputation (30x). Multivariable logistic regression analysis was performed to evaluate the association between the timing of inopressor initiation and 30-day mortality, adjusting for univariate significant confounders among variables known at admission. Results A total of 956 consecutive CS patients were included of whom 418 (43.7%) and 538 (57.3%) patients were subjected to early and late initiation of inopressors respectively. The most frequently used drug in both groups was noradrenaline. At baseline, patients in the early initiation group were younger (67.4 vs. 70.0 years, p &amp;lt;0.001), presented with a lower mean arterial pressure (MAP) (72.5 vs. 76.3, p = 0.048) and higher lactate (4.2 vs. 3.6, p = 0.012), and presented with a NSTEMI more often (36.0% vs. 14.2%, p &amp;lt;0.001). They also had a higher prevalence of previous myocardial infarction (33.9% vs. 22.9%, p &amp;lt;0.001) and previous CABG (14.3% vs. 6.2%, p &amp;lt;0.001). Moreover, 30-day mortality rates were higher in the early initiated group (48.6% vs. 37.6%, pLogrank &amp;lt;0.001). After multivariate adjustment for age, admission MAP and lactate, early inopressor initiation remained independently associated with 30-day mortality (OR 1.44, 95%-CI 1.08-1.98) compared to late initiation. Conclusion In this Dutch cohort of CS patients undergoing PCI, baseline- treatment- and outcome characteristics differed between patient categories receiving either early or late initiated inopressors. Patients who were subjected to early initiated inopressors were younger, presented with worse hemodynamics, had a more extensive cardiovascular medical history and higher 30-day mortality rates. The results of this study reemphasize the importance of identifying patients who benefit from inopressors.30-day mortality late vs. earlyTable patient characteristics

The prevalence and impact of changes in the severity of secondary TR during hospitalization in acute heart failure

Abstract Background Secondary tricuspid regurgitation (TR) is a prevalent entity in patients hospitalized for acute heart failure (AHF), and concomitant moderate or severe TR at admission has been demonstrated to be associated with a poor prognosis. However, no study has described the trajectories of the severity of secondary TR during admission, and the prognostic implications of changes in the severity of secondary TR. Purpose This study aimed to investigate the dynamism of secondary TR observed during hospitalization due to worsening heart failure, and its prognostic impact in patients with AHF. Methods A post-hoc analysis of 1,061 consecutive patients hospitalized with AHF was performed, enrolled in the prospective, multicenter Registry Focused on Very Early Presentation and Treatment in Emergency Department of Acute Heart Failure (REALITY-AHF). Patients included in the study underwent a comprehensive echocardiographic examination within 24 hours of admission and again prior to discharge. Patients were divided into four groups based on the TR severity at admission and discharge: none to mild TR at both admission and discharge (no/no group), moderate to severe TR at admission but improved to none to mild TR at discharge (resolution group), none to mild TR at admission but moderate to severe TR at discharge (worsening group), and moderate to severe TR at both admission and discharge (persistent group). The primary endpoint was the composite of 1-year all-cause mortality and HF re-hospitalization after discharge. Results The no/no, resolution, worsening, and persistent groups included 479 (45%), 275 (26%), 85 (8%), and 222 patients (21%), respectively. The no/no group and the resolution group had significantly lower tricuspid regurgitant pressure gradients prior to discharge compared to the worsening and persistent groups (P&amp;lt;0.001). Also, right ventricular dysfunction evaluated at discharge, defined by tricuspid annular plane systolic excursion &amp;lt;17 mm, was more prevalent in the worsening (65.7%) and persistent groups (66.4%) compared to the no/no (43.7%) and resolution (53.2%) groups (P&amp;lt;0.001). Compared to the no/no group, the worsening and persistent groups, but not the resolution group, were associated with a higher incidence of the primary endpoint (Log-rank: P&amp;lt;0.001). This association remained significant in an adjusted Cox regression analysis, with the worsening group (hazard ratio: 1.48, 95% confidence interval [CI]: 1.01–2.20) and persistent group (hazard ratio: 1.35, 95% CI: 1.01–1.83) independently associated with the primary endpoint, but not the resolution group (hazard ratio: 1.10, 95% CI: 0.81–1.49). Conclusions In patients hospitalized for AHF, the severity of secondary TR is dynamic, and changes in the severity of TR are significantly associated with prognosis. Our study results underscore the importance of repetitive evaluation of TR in hospitalized patients with AHF.

The cardioprotective potential of soluble urokinase Plasminogen Activator Receptor (suPAR) in myocardial ischemia

Abstract Background and aims: Increased circulating soluble urokinase plasminogen activator receptor (suPAR) levels are associated with adverse cardiovascular outcomes, however, any cardiovascular-related functions remain unknown. This study aimed to (i) document haemodynamic profiles in isolated rat hearts under the influence of suPAR, and to (ii) explore any mechanisms triggered by suPAR following myocardial ischaemia-reperfusion. Methods We undertook a 4-pronged approach (Figure 1). A Langendorff isolated rat heart model was used to perfuse all hearts with Krebs-Henseleit solution flowing retrogradely through the aorta at 37°C. A balloon inserted into the left ventricle allowed measurements of ventricular pressure, and a pressure transducer placed above the aorta recorded perfusion pressure for coronary flow rates. The experimental protocol consisted an initial 30-minute stabilisation period, followed by 40 minutes of ischemia via buffer flow cessation. Hearts were subsequently recovered during 90 minutes of reperfusion, receiving either suPAR treatment or perfusion buffer as controls. An inhibitor arm comprising co-infusion of suPAR and a monoclonal antibody capable of binding to suPAR was also assessed. Troponin T was measured in outflow perfusates collected at specific intervals. Proteins from hearts in treatment groups were separated using gel electrophoresis, with Western blotting to visualise the phosphorylation status of kinases (Akt, STAT). High-flow respirometry and fluorometry were investigated in cardiac mitochondria to determine respiration rates and ATP production in ischaemia reperfusion under the influence of suPAR. Statistical analysis was conducted with ANOVA using SPSS. Results Hearts receiving suPAR infusion at reperfusion (n = 16) showed a significant increase in developed pressure (p = .017) and lower perfusion pressure (p = .02) compared to controls (n = 16), revealing that suPAR-treated hearts recovered with better contractility and vasodilatory properties post-ischaemia. suPAR’s haemodynamic profiles in the antibody group were similar to controls, attenuating suPAR-induced effects (n = 8). Outflow effluents in suPAR-treated hearts obtained &amp;gt;3 fold lower serial Troponin T values than controls (p &amp;lt; .001). Heart tissues receiving suPAR treatment revealed a 1.7-fold increase in Akt (p = .001) and a 3.8-fold increase in STAT3 phosphorylation compared to controls (p &amp;lt; .001) and the inhibitor group (p = .04). Finally, suPAR increased mitochondrial ATP production by 28% (p = .013) compared to controls after ischaemia. Conclusion This is a world-first demonstration of suPAR’s cardioprotective influences in isolated rat hearts recovering from ischaemia. suPAR’s ability to promote cardiac contractility and vasodilation was associated with lesser injury as shown by Troponin T reduction. Mechanistically, suPAR infusion upregulated two key cardioprotective pathways, which may also function to protect cardiac mitochondria.Figure 1 - Schematic of Methods

Extreme Saharan dust events expand northward over the Atlantic and Europe, prompting record-breaking PM10 and PM2.5 episodes

Abstract. Unprecedented extreme Saharan dust (duxt) events have recently expanded northward from subtropical NW Africa to the Atlantic and Europe, with severe impacts on the Canary Islands, mainland Spain and continental Portugal. These six historic duxt episodes occurred on 3–5 and 22–29 February 2020, 15–21 February 2021, 14–17 January 2022, 29 January–1 February 2022, and 14–20 March 2022. We analyzed data of 341 governmental air quality monitoring stations (AQMSs) in Spain (330) and Portugal (11), where PM10 and PM2.5 are measured with European norm (EN) standards, and found that during duxt events PM10 concentrations are underestimated due to technical limitations of some PM10 monitors meaning that they can not properly measure extremely high concentrations. We assessed the consistency of PM10 and PM2.5 data and reconstructed 1690 PM10 (1 h average) data points of 48 and 7 AQMSs in Spain and Portugal, respectively, by using our novel “duxt-r” method. During duxt events, 1 h average PM10 and PM2.5 concentrations were within the range 1000–6000 µg m−3 and 400–1200 µg m−3, respectively. The intense winds leading to massive dust plumes occurred within meteorological dipoles formed by a blocking anticyclone over western Europe and a cutoff low located to the southwest, near the Canary Islands and Cape Verde, or into the Sahara. These cyclones reached this region via two main paths: by deviating southward from the Atlantic mid-latitude westerly circulation or northward from the tropical belt. The analysis of the 2000–2022 PM10 and PM2.5 time series shows that these events have no precedent in this region. The 22–29 February 2020 event led to (24 h average) PM10 and PM2.5 concentrations within the range 600–1840 and 200–404 µg m−3, respectively, being the most intense dust episode ever recorded on the Canary Islands. The 14–20 March 2022 event led to (24 h average) PM10 and PM2.5 values within the range 500–3070 and 100–690 µg m−3 in southeastern Spain, 200–1000 and 60–260 µg m−3 in central Spain, 150–500 and 75–130 µg m−3 in the northern regions of mainland Spain, and within the ranges 200–650 and 30–70 µg m−3 in continental Portugal, respectively, being the most intense dust episode ever recorded in these regions. All duxt events occurred during meteorological anomalies in the Northern Hemisphere characterized by subtropical anticyclones shifting to higher latitudes, anomalous low pressure expanding beyond the tropical belt and amplified mid-latitude Rossby waves. New studies have reported on recent record-breaking PM10 and PM2.5 episodes linked to dipole-induced extreme dust events from North Africa and Asia in a paradoxical context of a multidecadal decrease in dust emissions, a topic that requires further investigation.

Numerical Simulation and Model Test on Pressure Fluctuation and Structural Characteristics of Lightweight Axial Flow Pump

In order to explore the relationship between the hydraulic performance, pressure pulsation, and structural characteristics of lightweight axial flow pumps, this paper takes the axial flow pump as the research object and analyzes pressure pulsation and structural characteristics by changing the blade length and thickness to realize the lightweight design of the axial flow pump impeller. Compared with the initial scheme (Scheme 1), the mass of the impeller is reduced by 17.2% (Scheme 2) and 29.9% (Scheme 3), respectively. The lightweight axial flow pump (Scheme 2 and Scheme 3) has a lower pressure pulsation amplitude at the impeller outlet monitoring point under large flow conditions. After the lightweight design of the axial flow pump impeller, the blade becomes shorter, the mass becomes lighter, and the cavitation performance will become worse. The maximum equivalent stress of Scheme 2 and Scheme 3 is increased by 2.8% and 31.9%, respectively, compared to Scheme 1. The maximum deformation of Scheme 3 increased by 27% compared to Scheme 1. This research can provide guidance for the lightweight optimization design of the axial flow pump.

Aortic valve tract dynamics in normal-flow low-gradient and normal-flow high-gradient severe aortic stenosis

Abstract Introduction Aortic stenosis (AS) is the most common valvular heart disease in developed countries. Severe AS is defined as a mean pressure gradient (MG) ≥ 40 mmHg, a maximum aortic jet velocity≥4 m/s and an aortic valve area (AVA)≤1 cm2. However, classification of AS severity may be challenging due to discordant results on echocardiography. The normal-flow low-gradient severe AS (NFLG-AS) is defined as AVA≤1 cm2, MG&amp;lt;40 mmHg, left ventricular ejection fraction ≥ 50%, and stroke volume index (SVi) ≥ 35 ml/m2, whereas in the presence of MG &amp;gt; 40mmHg the condition is described as normal-flow high-gradient AS (NFHG-AS). Purpose The purpose of this study was to seek differences in the dynamic changes of the aortic valve tract throughout the cardiac cycle between the two clinical entities: NFHG-AS (Group 1) and NFLG-AS (Group 2). Methods In total, 130 patients with normal flow severe AS who underwent TAVI and had 3D transoesophageal echocardiographic data sets were screened. 38 patients with NFHG-severe AS and 40 patients with NFLG-severe AS with matching clinical characteristics and aortic valve area were identified. A custom-made semi-automated application developed by SQ was used. The application allows tracking of the aortic valve tract surface throughout the cardiac cycle in 3D transoesophageal echocardiograms and provides measurements of the geometrical planes at 4 levels: left ventricular outflow tract (LVOT), aortic annulus (AoA), sinuses of Valsalva (SoV) and sinotubular junction (STJ). Results The echocardiographic characteristics and the dynamic changes of the aortic valve tract between the two groups are shown in Tables 1 and 2. Both groups had comparable echocardiographic characteristic apart from the mean aortic valve pressure gradient as expected. With regards to the aortic valve tract geometrical dynamic changes, the relative LVOT and AoA area changes were bigger in Group 1 (36.8±15.9% vs 29.1±11.9%; p=0.017 and 21.0±8.39% vs 17.1±6.6%; p=0.028). The SoV and STJ relative changes were similar between the two groups. The same applies to aortic stiffness parameters, namely compliance and distensibility of the ascending aorta, systemic arterial compliance, and valvulo-arterial impedance. Conclusion The LVOT and aortic annulus area demonstrate more prominent dynamic changes in patients with normal-flow high-gradient severe AS compared to individuals with normal-flow low-gradient severe AS. While the SoV and the STJ geometry does not change significantly through the cardiac cycle, a more elastic outflow tract allows larger expansion in systole and higher pressure gradients across the aortic valve, whereas a stiffer outflow tract and annulus result in lower pressure gradients, despite the presence of severe aortic stenosis (AVA&amp;lt;1.0cm2). These differences in dynamic LVOT and aortic annulus changes may explain the discrepancy between aortic valve area and pressure gradients in patients with normal-flow low-gradient AS.

Relative size matters: Spawning substrate roughness size and spacing affect egg dislodgement and retention in the benthos

AbstractThe consequences of hydrodynamic effects on survival of embryonic benthic organisms remain unknown. This is because the interaction of hydrodynamics and substrate roughness is complex, but it can be conceptualized in two dimensions by roughness flow regimes (isolated, wake interference, and skimming flow) or roughness types (k‐ and d‐type). We examined the effect of different roughness flow regimes/roughness types and roughness heights (k) on the dislodgement of walleye (Sander vitreus) eggs (2 mm diameter, ⌀) using a wall jet apparatus. We expected that lower wall shear stress (τw) would be required for dislodgement in more‐exposed/less‐sheltered roughness type/flow regimes (i.e., k‐type/isolated roughness flow) and when k ≤ ⌀. Surprisingly, the opposite was found, indicating that other mechanism(s) are also responsible for egg dislodgement on these rough surfaces. Hydrodynamic sheltering occurred when flow was directed over exposed eggs (k ≤ ⌀) adjacent to roughness elements effectively increasing their width, and thus requiring higher τw for rolling and then ejection. When k &gt; ⌀, eggs dislodgement likely occurred via the lower pressure in the eddies recirculating in the groove width between roughness elements, rather than due to τw. These results indicate the relevance of heterogeneous sorting and sizing of substrate elements to provide suitable spawning habitats in benthic environments.

Modeling Three-Dimensional Exfiltration Rates from Permeable Street Stormwater Inlets as One-Dimensional Water Flux in Urban Hydrological Models

Climate change has increased the intensity and frequency of weather systems, increasing the risk of inundation in urban areas. To mitigate these risks, not only rivers but also entire catchments need to be managed, and the use of infiltration and retention units needs to be expanded. The ability to evaluate the effects of promoting infiltration and retention in catchments using distributed hydrological models, clarify the three-dimensional behavior of exfiltration from catchments into natural base soils, and parameterize this flow as a one-dimensional hypothetical water flux is essential. Using VGFlow2D (Forum8) and field observations, numerical analyses were conducted to parametrize the flux and assess the features of q/Ks values, representing the volume of three-dimensional water exfiltration from stormwater inlet bases into natural soils relative to the saturated hydraulic conductivity (Ks) of the soils. The findings were integrated into the hydrological model Infoworks ICM (Innovyze) by adding a single parameter, the “exfiltration loss rate”, to each inlet without increasing computational demands. The obtained q/Ks values were compared to previously reported values, and variations were evaluated using infiltration theory.

A Decade-Long Retrospective Study of Factors Influencing Survival in Ruptured Abdominal Aortic Aneurysm.

Background: Ruptured abdominal aortic aneurysm (rAAA) carries a high mortality risk, requiring rapid diagnosis and intervention. This study assesses various clinical factors influencing rAAA management outcomes in alignment with evolving guidelines from 2011 to 2024. Methods: A retrospective analysis of 62 rAAA patients treated at Vivantes Clinic, Berlin, from July 2014 to May 2024 was conducted. Data were obtained from medical records, focusing on vital parameters at admission and during treatment. Both numerical and categorical variables were analyzed to identify survival determinants. Results: The overall survival rate was 55%. Significant differences in systolic and diastolic blood pressures during surgery were noted between survivors and non-survivors, with lower pressures observed in non-survivors at critical surgical stages. Other vital signs showed no significant variations. Survival was significantly associated with gender, fluid therapy, and aneurysm location. Conclusions: Effective blood pressure management during surgery is crucial for improving survival in rAAA cases. This study emphasizes adherence to current clinical guidelines and highlights the need for ongoing research to fill existing knowledge gaps. Further investigations are essential to enhance patient care and outcomes in rAAA.

Simulation study on the cavitation flow characteristics of liquid ammonia in the nozzle under high-pressure injection conditions

In this study, a non-isothermal compressible cavitating flow simulation model for liquid ammonia in high-pressure injector, accounting for the phase change properties, was established. The model was validated using experimental data from existing literature. The cavitation phase change process of liquid ammonia within the injector nozzle was investigated, and the differences in cavitation distribution between ammonia and diesel were explored. The results indicate that with increasing injection pressure, the vapor volume fraction of ammonia increases linearly, while that of diesel fuel shows a rapid initial rise followed by a decelerating trend. In terms of flow coefficient, ammonia is lower than diesel, though the two values converge at higher injection pressures. Under low injection pressure, the heat absorbed by the cavitation phase change of ammonia exceeded the heat generated by the high-speed friction of ammonia flow against the nozzle wall, leading to a temperature drop at the nozzle inlet. Conversely, at high injection pressure, the temperature of ammonia on the nozzle wall increases by more than 20 K, resulting in a rapid rise in saturated vapor pressure and significantly intensifying the cavitation effect. Compared to ammonia, diesel experienced a higher temperature rise within the nozzle but exhibited smaller variations in saturated vapor pressure, making the temperature effect on cavitation less pronounced. Diesel’s higher density and viscosity resulted in lower flow velocities compared to ammonia, leading to more developed cavitation in the lower wall region of the nozzle and creating a higher pressure region on the upper wall of the nozzle, which was more distant from the nozzle inlet and inhibited cavitation development there. The research results provide theoretical support for the design of liquid ammonia injectors.

Metagenomic analysis of deep-sea bacterial communities in the Makassar and Lombok Straits

The extreme conditions of the deep-sea environment, including limited light, low oxygen levels, high pressure, and nutrient scarcity, create a natural habitat for deep-sea bacteria. These remarkable microorganisms have developed unique strategies to survive and adapt to their surroundings. However, research on the diversity of deep-sea bacteria, both culture-dependent and culture-independent, in Indonesian waters remains insufficient. This study focused on exploring the biodiversity of deep-sea bacteria, specifically in the Makassar and Lombok Strait, the main Indonesian throughflow pathway characterized by relatively fertile water, which serves as an important deep-sea region. High-throughput DNA sequencing of full-length 16S rRNA was employed to construct a genomic database. The results of the bioinformatic analysis revealed that two stations, 48 and 50 (Makassar Strait), exhibited a more similar community structure of deep-sea bacteria than did station 33 (Lombok Strait). Among the predominant phyla found at a depth of 1000 m, the top ten were Proteobacteria, Firmicutes, Bacteroidetes, Actinobacteria, Planctomycetes, Acidobacteria, Nitrospinae, Verrucomicrobia, Candidatus Melainabacteria, and Cyanobacteria. Furthermore, the genera Colwellia, Moritella, Candidatus Pelagibacter, Alteromonas, and Psychrobacter consistently appeared at all three stations, albeit with varying relative abundance values. These bacterial genera share common characteristics, such as psychrophilic, halophilic, and piezophilic tendencies, and are commonly found in deep-sea ecosystem. The environmental conditions at a depth of 1000 m were relatively stable, with an average pressure 10 MPa, temperature 4.68 °C, salinity 34.58 PSU, pH 8.06, chlorophyll-a 0.29 µg/L, nitrate 3.19 µmol/L, phosphate 6.32 µmol/L and dissolved oxygen (DO) 2.90 mg/L. The bacterial community structures at the three sampling stations located at the same depth (1000 m) exhibited similarities, as indicated by the closely aligned similarity index values.

Understanding perioperative risk determinants in carotid endarterectomy: the impact of compromised circle of Willis morphology on inter-hemispheric blood flow indices based on intraoperative internal carotid artery stump pulse pressure and backflow patterns.

Carotid artery stenosis (CAS) often requires surgical intervention through carotid endarterectomy (CEA) to prevent stroke. Accurate cerebrovascular risk assessments are crucial in CEA, as poor collateral circulation can lead to insufficient interhemispheric blood flow compensation, resulting in ischemic complications. Therefore, understanding perioperative risk determinants is vital. This study aims to determine the impact of compromised circle of Willis (CoW) morphology on inter-hemispheric blood flow, focusing on indices based on intraoperative internal carotid artery stump pulse pressure and backflow patterns. In 80 CAS patients who underwent CEA, preoperative CT angiography for CoW was conducted. Patients were categorized into five subgroups based on their CoW anatomy and three additional groups based on intraoperative internal carotid artery (ICA) stump backflow patterns evaluated by the surgeon. Continuous blood pressure signals, including systolic, diastolic, mean, and pulse pressure values, were recorded during the procedure. The relationship between CoW anatomical variants and the systolic and diastolic segments of the averaged pressure waveforms, particularly diastolic pressure decay, was analyzed. The correlation between CoW anatomy and stump backflow intensity was also examined. Significant variability in ICA stump backflow and pressure values was evident across CoW variants. Patients with compromised CoW morphology exhibited weaker backflow patterns and lower ICA stump pulse pressure values, consistent with impaired interhemispheric blood flow. Notably, ICA stump diastolic pressure decay was consistent across most CoW variant groups, indicating developed collateral circulation in cases with CoW anomalies. Thus, impaired CoW integrity is associated with compromised interhemispheric blood flow indices based on intraoperative ICA stump pulse pressure and backflow patterns during CEA. Integrating intraoperative pulse waveform analysis with preoperative CT angiography provides a more detailed assessment of cerebrovascular risk, guiding the selective use of shunts. This combined approach may improve surgical outcomes and patient safety by identifying patients at increased risk of perioperative neurological events due to CoW anomalies.

Tropospheric Response to Gulf Stream Intrinsic Variability: A Model Ensemble Approach

AbstractThe Gulf Stream's (GS) impact on the marine boundary layer (MBL) is well established, yet the mechanisms and timescales through which it affects the upper‐troposphere and contributes to precipitation are debatable. Using a high‐resolution regional atmospheric model, we shed light on the impact of ocean intrinsic variability (OIV) along GS on midlatitude‐atmosphere. Taking advantage of a 24‐member ensemble of ocean model integrations, we devised a novel experimental setup where the same weather system feels different realizations of GS sea surface temperature (SST). We introduce the “Eddy Recharge‐Frontal Lift” (ERFL) mechanism, highlighting the joint importance of synoptic variability and boundary layer processes. ERFL mechanism proposes that OIV recharges/discharges MBL with moisture and heat, while convergence associated with passing atmospheric‐fronts uplifts these MBL‐trapped anomalies to upper‐troposphere and imprints on precipitation in surprisingly short periods (a month). The impact of OIV on precipitation depends on the background mean SST.

Understanding the Enhanced Separation Mechanism of C2H4/C2H6 at Low Pressure by HKUST−1

The production of ethylene (C2H4) is typically accompanied by the formation of impurities like ethane (C2H6), making the separation of C2H4 and C2H6 crucial in industrial processes. Here, we investigated the S-shaped adsorption phenomenon of C2H6 on the metal–organic framework HKUST−1. The virial equation is used to fit the C2H6 and C2H4 adsorption isotherms under low coverage. The results showed that the repulsion energy between neighboring C2H6 molecules was significantly higher than that between neighboring C2H4 molecules, which was an important reason for the lower adsorption of C2H6 by HKUST−1 at low coverage. As more molecules are adsorbed, gas molecules aggregate within pores, leading to more hydrogen bonds formed between HKUST−1 and larger-sized C2H6 under high coverage conditions. This phenomenon plays a crucial role in the S-shaped adsorption behavior of HKUST−1 on C2H6. Additionally, this unique adsorption behavior allows for the efficient separation of C2H4/C2H6 mixtures at low pressures. The ideal adsorbed solution theory (IAST) selectivity of HKUST−1 for C2H4/C2H6 mixtures was 3.78 at 283 K and 1 bar, but increased significantly to 7.53 under low pressure. This unique mechanism provides a theoretical basis for the low-pressure separation of C2H4/C2H6 by HKUST−1 and establishes a solid foundation for future practical research applications.

Explosion limits of binary mixtures of ammonia and additives (hydrogen, natural gas, and diethyl ether)

This study investigates the explosion limits of ammonia (NH3) and the effect of three different active fuels, hydrogen (H2), natural gas (NG), and diethyl ether (C2H5OC2H5, DEE), on the explosive characteristics of NH3 through comprehensive chemical kinetics analysis. The results reveal that the explosion limits of NH3 exhibit the narrowest explosive range and display comparatively weakest explosive reactivity among the four fuels, presenting a monotonic changing trend. Reaction pathway analysis unveils that with increasing temperature, NH2 tends to oxidize more predominantly through the NH-N2H2-NNH-N2 pathway, while the conversion of NH2 to H2NO pathway decreases. Therefore, the introduction of active fuels significantly enhances the explosive reactivity of NH3. However, their impact under various temperature-pressure conditions presents nuanced and diversified characteristics. When a 0.5 % mole fraction of active fuel is added to NH3, DEE exhibits the most significant enhancement in medium to high-pressure conditions, while H2 predominates at low pressure, with NG consistently demonstrating the least pronounced enhancement. Upon the active fuel proportion being increased to 20 %, the promoting effect of DEE remains the most significant in the medium to high-pressure region, while NG has surpassed H2 as the secondary dominant fuel. In the low-pressure region, NH3-H2 still demonstrates the highest reactivity, followed by NH3-DEE, while NH3-NG exhibits the least reactivity. These findings provide valuable insights into the widespread utilization and scientific exploration of ammonia as a fuel source.

Compliant Interconnects Based on Single Micrometer-sized Metal-Coated Polymer Spheres.

The rapid evolution of multifunctional electronics necessitates interconnection technologies appropriate for large dies with high-density and/or ultrafine pitch input/output pins. Existing technologies face numerous challenges, including demands for bonding equipment that can deliver extremely high force as well as thermo-mechanical stresses induced in the assembled packages due to mismatched thermal expansion of materials involved. This study proposes an approach to compliant interconnects comprising single micrometer-sized metal-coated polymer spheres, being joined to mating electrodes by sintering of Ag nano ink at low temperature (140 °C) and low pressure (∼15 mN/particle). Such an interconnection technology is expected to enhance the thermo-mechanical robustness of the assembled packages as well as be capable of high-density, ultrafine pitch interconnects. Our approach demonstrates control over conductive particles during assembly, achieving a 98% success rate in individual interconnects with a single captured particle. The use of sintered Ag not only secures free-standing particles on electrical pads (with an adhesion force above 2 μN) but also results in a 15% reduction in interconnect resistance, with measured resistance as low as 0.5 Ω, compared to interconnects without Ag ink. This method presents an alternative to metallurgical joints, particularly suited for high-density, ultrafine pitch applications, offering low bonding pressure and temperature, along with improved interconnect compliance to enhance the thermo-mechanical robustness of the packages.