Pressure Gradient Research Articles

Optimizing bioconvective heat transfer with MHD Eyring–Powell nanofluids containing motile microorganisms with viscosity variability and porous media in ciliated microchannels

Purpose This paper aims to optimize bioconvective heat transfer for magnetohydrodynamics Eyring–Powell nanofluids containing motile microorganisms with variable viscosity and porous media in ciliated microchannels. Design/methodology/approach The flow problem is first modeled in the two-dimensional frame and then simplified under low Reynolds number and long wavelength approximations. The numerical method is used to examine the impact of thermal radiation, temperature-dependent viscosity, mixed convection, magnetic fields, Ohmic heating and porous media for velocity, temperature, concentration and motile microorganisms. Graphical results are presented to observe the impact of physical parameters on pressure rise, pressure gradient and streamlines. Findings It is observed that the temperature of nanofluid decreases with higher values of the viscosity parameter. It is absolutely in accordance with the physical expectation as the radiation parameter increases, the heat transfer rate at the boundary decreases. Nanoparticle concentration increases by increasing the values of bioconvection Rayleigh number. The density of motile microorganisms decreases when bioconvection Peclet number is increased. The velocity of the nanofluid decreases with higher value of Darcy number. With increase in the value of bioconvection parameter, the flow of nanofluid is increased. Originality/value The bioconvective peristaltic movement of magnetohydrodynamic nanofluid in ciliated media is proposed. The non-Newtonian behavior of the fluid is described by using an Eyring–Powell fluid model.

Interannual Variability of the South Equatorial Current in the Southeast Indian Ocean Associated with El Niño–Southern Oscillation

Abstract Interannual variability of the South Equatorial Current (SEC) in the southeast Indian Ocean is investigated using Archiving, Validation, and Interpretation of Satellite Oceanographic Data (AVISO) and Global Ocean Reanalysis and Simulations (GLORYS) data from January 1993 to December 2022 and a 1.5-layer reduced-gravity model. Interannual variability of the SEC averaged over the upper 200 m in the southeast Indian Ocean is influenced by El Niño–Southern Oscillation (ENSO). The SEC has a significant positive correlation with the Niño-3.4 index and lags the Niño-3.4 index by 12–15 months, with the SEC weakening significantly during the decaying years of El Niño events and vice versa for La Niña events. Mechanistic studies suggest that during the developing years of El Niño events, the northward sea level anomaly (SLA) pressure gradient between the negative SLA off Sumatra–Java coast and the positive SLA of SEC region (90°–115°E, 9°–13°S) strengthens the SEC under geostrophic equilibrium. During the decaying years of El Niño events, the negative SLA in the tropical western Pacific Ocean propagates through the Maritime Continent to the SEC region. The SLA pressure gradient between the Sumatra–Java coast and the SEC region reverses to southward. This induces an eastward geostrophic current anomaly under geostrophic equilibrium, significantly weakening the SEC. The converse holds for La Niña events. Local wind in the southeast Indian Ocean has a suppressive effect on the SLA propagated to this area. The results of the 1.5-layer reduced-gravity model verify these phenomena, and the westward-propagating SLA from the Maritime Continent induced by the Pacific wind plays a dominant role in the SLA variation in the SEC region from model experiment. This study can improve the understanding of the effects of ENSO processes on ocean circulation in the southeast Indian Ocean.

Microemulsions and Nanoparticles: The Sustainable Future of Drilling Fluids in Oil Exploration

Objective: This study aims to contextualize the advancements in the application of nanoparticles, microemulsions, and nanoemulsions in drilling fluids, highlighting their contributions to the efficiency and sustainability of operations in the oil industry. Theoretical Framework: The research is grounded in principles of nanotechnology and fluid dynamics, analyzing the role of drilling fluids in aspects such as wellbore instability, rheological properties, filtration, and physicochemical characteristics. Method: A systematic literature review was conducted, encompassing scientific articles, conference papers, technical books, and patents. The research included both foundational and recent studies to identify trends and advancements in drilling fluid formulations. Results and Discussion: Drilling fluid formulations have evolved to address challenges such as diverse well geometries, extreme temperature and pressure gradients, and environmental regulations. The incorporation of nanoparticles into drilling fluids has demonstrated benefits such as reduced circulation losses and increased resistance to high pressures and temperatures. Nanoemulsions and microemulsions have shown reduced environmental impact compared to oil-based fluids, along with improved filtration properties, rheology, and thermal resistance compared to water-based fluids. Research Implications: The findings underscore the importance of nanoparticles and nanoemulsion and microemulsion systems for enhancing the efficiency and sustainability of drilling fluids, meeting the demand for environmentally responsible solutions. Originality/Value: This study provides a comprehensive analysis of advancements in drilling fluid formulations, emphasizing the sustainable potential of nanoparticles, nanoemulsions, and microemulsions, and reinforcing their relevance to the future of the oil industry.

Energy thickness in turbulent boundary layer flows

In this study, we investigate the properties of energy thickness $\delta _3$ in turbulent boundary layer (TBL) flows, a parameter derived solely from the mean streamwise velocity ( $U$ ) profile. Through an analysis of the energy integral equation for zero pressure gradient TBLs, we establish a close relationship between turbulent kinetic energy (TKE) production and $\delta _3$ , offering a practical method to estimate TKE production, which is particularly useful in physical experiments where direct measurements are challenging. The significance of $\delta _3$ becomes even more pronounced in TBLs under pressure gradient. Through extensive analysis of numerical and experimental data, we show that the ratio between $\delta _3$ and the momentum thickness $\delta _2$ is a promising criterion for predicting flow separation. Moreover, we derive a new energy integral equation for TBLs under arbitrary pressure gradients, and provide approximations for TKE productions terms by $R_{uv}\,\partial U/\partial y$ and $R_{uu}\,\partial U/\partial x$ , and dissipation term by the mean shear. Here, $x, y$ represent the streamwise and wall-normal directions, respectively, and $R_{uu}$ and $R_{uv}$ are the Reynolds normal and shear stresses. The accuracy and robustness of the new energy integral equation and the approximation equations are validated using direct numerical simulations data. Our results show that the TKE production by $R_{uv}\,\partial U/\partial y$ and the overall productions consistently remain positive, reflecting a continuous conversion of mean kinetic energy into TKE across all TBLs. However, under strong favourable pressure gradients, TKE production by $R_{uu}\,\partial U/\partial x$ becomes negative, indicating a reverse energy transfer from TKE to mean kinetic energy.

The influence of trailing edge flaps on the aerodynamic characteristics of S1223 aerofoil

The S1223 aerofoil is a low Reynolds number high lift aerofoil. Analysing the aerodynamic characteristics of this aerofoil can provide a theoretical basis for enhancing flight efficiency in the design of small unmanned aerial vehicles. This study employed the k--SST turbulence model in the fluid simulation software (ANSYS Fluent) to conduct two-dimensional numerical aerodynamic simulations on the original aerofoil and its modified versions, which included flaps (deflected 10 at 70% chord length) and slotted flaps (deflected 10 at 70% chord length with a slot width of 1.5% of the chord). The aerofoil's aerodynamic performance was confirmed by comparing lift and drag coefficients at different angles of attack under Reynolds number 5.0105, as well as by analysing the pressure and velocity gradients in the flow field. The results indicate that both the lower flap and the slotted flap can greatly enhance the lift-to-drag ratio. In contrast, slotted flaps delay boundary layer separation, providing greater lift at high angles of attack while reducing the impact on drag.

Effect of Blade Number on Internal Flow and Performance Characteristics in Low-Head Cross-Flow Turbines

Cross-flow turbines are widely used in microhydropower systems because of their cost-effectiveness, environmental sustainability, adaptability, and robust design. However, their relatively lower efficiency than other turbine types limit their application in large-scale projects. Previous studies have identified poor flow profiles as a significant factor contributing to inefficiency, with the number of blades playing a critical role in the flow behavior, efficiency, and structural stability. This study employed numerical simulations to analyze how varying the number of blades affects the internal flow characteristics and performance of the turbine at, and off, its best operating points. Configurations with 16, 20, 24, 28, 32, 36, 40, and 44 blades were investigated under constant low-head conditions, fully open valve settings, and varying runner speeds. Simulations were performed using ANSYS CFX, incorporating steady-state conditions, a two-phase flow model with a movable free surface, and a shear stress turbulence model. The results indicate that the 28-blade configuration achieved a maximum hydraulic efficiency of 83%, outperforming the preset 24-blade setup by 6%. Flow profiles were examined using pressure and velocity gradients to identify regions of adverse pressure. Due to the impulse nature of the turbine, the flow profile is more sensitive to changes in the flow speed than to pressure. The flow trajectory showed stability in the first stage but exhibited discrepancies in the second stage, which were attributed to turbulence, recirculation, and shaft flow impingement. The observed performance improvements were linked to reduced hydraulic losses due to flow separation and friction, emphasizing the significance of the number of blades and the regions of optimal efficiency under low-head conditions.

Increased resting heart rate indicates high-workload hearts with augmented aortic hydraulic power in hypertensive pigs.

Clarifying the inceptive pathophysiology of hypertensive heart disease helps to impede the disease progression. Through coarctation of the infrarenal abdominal aorta (AA), we induced hypertension in minipigs and evaluated physiological reactions and morpho-functional changes of the heart. Moderate aortic coarctation was achieved with approximately 30 mmHg systolic pressure gradient in minipigs. Hypertension was assessed by pressure increment of the carotid artery. Perioperative heart rate (HR) was recorded. We measured aortic flow rate and pressure proximal to coarctation to calculate hydraulic power, an indicator for cardiac workload, and resistance. The hearts harvested at sacrifice were examined for myocardial hypertrophy, fibrosis, and dysfunction. The parameters capable of indicating high-workload heart and their prediction effectiveness were determined by cluster and receiver operating characteristic (ROC) analyses. Prolonged AA coarctation for 8-12 weeks induced hypertension in a portion of minipigs. The cluster of minipigs exhibiting increased aortic hydraulic power displayed hypertension and mean HR elevation without changing arterial resistance. Notably, the blood pressure and HR were measured under full anesthesia, equivalent to resting status. Myocardial hypertrophy was not detected at the tissue, cellular or molecular levels. Expression of biomarkers for cellular stress and heart failure didn't increase except for heat shock protein 40. ROC analysis showed that aortic hydraulic power, resting HR, and mean blood pressure, but not arterial resistance, can serve as the indicators for high-workload hearts. These results suggested that resting HR increase in hypertensive pigs indicates hearts with high workload. Heart failure may develop without appropriate treatment.

Differential determinants and prognostic value of aortic valve sclerosis over carotid atherosclerosis.

Aortic valve sclerosis (AVS) is a progressive atherosclerotic disease associated with future cardiovascular events (CVE). However, whether its development and prognostic value are independent of arterial atherosclerosis has not been thoroughly investigated. We evaluated the determinants and prognostic value of AVS in conjunction with carotid atherosclerosis. 4688 consecutive patients who underwent carotid ultrasonography and echocardiography were followed for an average of 3.6 ± 1.3 years, excluding those with bicuspid aortic valve, rheumatic heart disease, overt aortic stenosis, and prior aortic valve replacement. AVS was defined as any thickened cusps with hyper-echogenicity but a peak pressure gradient <2.5 m/s. The mean age of the patients was 61.1 ± 11.7 years, with 1836 (39 %) being women. Among them, 523 (11 %) had AVS. AVS was independently correlated with age, diabetes, lower high-density lipoprotein levels, and presence of carotid plaques. Moreover, it was significantly related to atherosclerotic CVE (acute coronary syndromes, and all-cause death; log-rank p = 0.011) and future heart failure (HF) admissions (p < 0.001). In multivariate analyses, AVS was significantly associated with atherosclerotic CVE regardless of age and sex but significantly attenuated by the presence of carotid plaques. Meanwhile, future HF admission was attenuated considerably after adjusting for E/e' and left ventricular (LV) ejection fraction. AVS has prognostic value for future CVE and HF. Atherosclerotic CVE was primarily mediated by vascular atherosclerosis; however, future HF admissions were mainly mediated by concomitant LV systolic and diastolic dysfunction, suggesting that AVS serves as a surrogate marker rather than an independent risk factor.

EVALUATION OF THE RESULTS OF AORTIC VALVE NEOCUSPIDIZATION WITH AUTOLOGOUS PERICARDIUM USING THE OZAKI TECHNIQUE IN AORTIC ROOT SURGERY

HighlightsThe main surgical interventions for aortic valve pathology at the aortic root site are aortic valve replacement and redo replacement. The Ozaki procedure emerged in the last decade; it involves replacement of the aortic valve using autologous pericardium. Despite the fact that many centers perform the Ozaki procedure frequently, there are few studies on the comparative evaluation of its efficacy. This necessitated the present study, which compares three groups of patients operated on using different techniques. Aim. To compare the short- and medium-term results of the Ozaki procedure and aortic valve replacements using mechanical and biological valves.Methods. The retrospective study included 189 patients operated on for aortic malformation at the Cardiac Surgery Department of Sechenov University from 2017 to 2022. Three groups of patients were formed: patients undergoing Ozaki procedure were included in the Ozaki group (70 patients), patients undergoing aortic valve replacement using mechanical prosthesis were included in the Mechanical valve group (62 patients), and patients undergoing aortic valve replacement using biological prosthesis were included in the Biovalve group (57 patients). The Ozaki procedure was performed in case the diameter of the aortic annulus was ≤ 25 mm. All mid-term outcomes were assessed after at least 6 months (mean follow up period was 20 months). The primary end points were mean and peak aortic valve gradient, 30-day mortality in the short-term postoperative period, and midterm mortality (≥ 6 months).Results. The mean gradient in the Ozaki, Biovalve, and Mechanical valve groups were 10.67 ± 7.15, 15.94 ± 21, and 17.87 ± 7.52 mm Hg. The peak gradient in the Ozaki group decreased from 81.7 ± 32.5 to 21.01 ± 13.22 mm Hg (in the in-hospital setting). 6 months after surgery, the peak gradient values were 18.98 ± 16.17 mm Hg. The in-hospital mortality rates in the Ozaki, Mechanical valve and Biovalve groups were 2.86, 5.26, and 6.45%, respectively. The overall mid-term mortality in three groups was 6/189, 3.17% (95% CI: 1.5–6.07), p = 0.172.Conclusion. In the short- and mid-term period, Ozaki procedure is superior to aortic valve replacement techniques in terms of aortic valve pressure gradient and comparable in terms of mortality.

Motile cilia modulate neuronal and astroglial activity in the zebrafish larval brain.

The brain uses a specialized system to transport cerebrospinal fluid (CSF), consisting of interconnected ventricles lined by motile ciliated ependymal cells. These cells act jointly with CSF secretion and cardiac pressure gradients to regulate CSF dynamics. To date, the link between cilia-mediated CSF flow and brain function is poorly understood. Using zebrafish larvae as a model system, we identify that loss of ciliary motility does not alter progenitor proliferation, brain morphology, or spontaneous neural activity despite leading to an enlarged telencephalic ventricle. We observe altered neuronal responses to photic stimulations in the optic tectum and hindbrain and brain asymmetry defects in the habenula. Finally, we investigate astroglia since they contact CSF and regulate neuronal activity. Our analyses reveal a reduction in astroglial calcium signals during both spontaneous and light-evoked activity. Our findings highlight a role of motile cilia in regulating brain physiology through the modulation of neural and astroglial networks.

A Fuel Cell Power Supply System Equipped with Artificial Gill Membranes for Underwater Applications.

This work proposes a fuel cell power supply system for underwater applications (e.g., autonomous underwater vehicles), where artificial gills, based on a polymer membrane,harvest the required oxygen from the ambient water. In this system, a circulating air-flow continuously supplies a proton exchange membrane fuel cell with oxygen, which is replenished using a polymer membrane. The membrane serves as the interface between the circulating air-flow and the ambient water, preventing water flux while allowing an oxygen flux across the membrane, driven by a partial oxygen pressure gradient. To demonstrate the feasibility of this concept, a prototype system was built based on guidelines derived from a mathematical model that was developed to describe the oxygen transfer process. A computational fluid dynamics model is developed and validated against the measurements from the prototype, resulting in a digital twin. The analysis indicates that the proposed power supply system has the potential to be superior to any battery-based solution currently available.

Safety and Efficacy of Portal Vein Recanalization with Creation of Intrahepatic Portosystemic Shunt (PVR-TIPS) to Treat Chronic Portal Vein Thrombosis in Non-cirrhotic Patients.

This study assesses the efficacy and safety of Portal Vein Recanalization with Intrahepatic Portosystemic Shunt (PVR-TIPS) in non-cirrhotic patients with chronic portal vein occlusion (CPVO), cavernomatous transformation, and symptomatic portal hypertension (PH) and/or portal vein thrombotic progression. Medical records of 21 non-cirrhotic patients with CPVO and portal cavernoma undergoing PVR-TIPS were analyzed. Hemodynamic (intraprocedural reduction in portosystemic pressure gradient), clinical (data on gastrointestinal bleeding, abdominal pain, ascites, and presence of esophageal varices from imaging exams) and technical success (PVR-TIPS) assessed efficacy. Safety was determined through complications classified according to the CIRSE Classification System. PVR-TIPS was successfully performed in all patients, resulting in a significant reduction in portal pressure gradient by 10mmHg (21.475 ± 9.7mmHg - 11.454 ± 5,4mmHg, p < 0.001), alleviating portal hypertension symptoms without thrombotic progression. Clinical success included resolution or reduction of ascites (p = 0.016), gastroesophageal varices (p = 0.004), abdominal pain (p = 0.0021), and cessation of gastrointestinal bleeding (p = 0.021). Complications occurred in 33% of patients, including six grade III events (1 perioperative liver bleeding, 5 delayed stent occlusions) and one grade VI event resulting in death (4.8%). Primary patency rate was 76% (21.3months, range:0.2-82), secondary patency 100% (4months, range:3.8-40.8). Survival at follow-up was 90.4%, with one unrelated death. One patient underwent liver transplantation, three became eligible post-recanalization. PVR-TIPS proves effective and safe in reducing portal pressure gradient, thereby alleviating PH symptoms without evidence of portal thrombosis progression in non-cirrhotic patients with CPVO and portal cavernoma. It expands therapeutic options, including liver transplantation.

Prediction of Cardiac Remodeling and/or Myocardial Fibrosis Based on Hemodynamic Parameters of Vena Cava in Athletes.

This study aimed to assess the hemodynamic changes in the vena cava and predict the likelihood of Cardiac Remodeling (CR) and Myocardial Fibrosis (MF) in athletes utilizing four-dimensional (4D) parameters. A total of 108 athletes and 29 healthy sedentary controls were prospectively recruited and underwent Cardiac Magnetic Resonance (CMR) scanning. The 4D flow parameters, including both general and advanced parameters of four planes for the Superior Vena Cava (SVC) and Inferior Vena Cava (IVC) (sheets 1-4), were measured and compared between the different groups. Four machine learning models were employed to predict the occurrence of CR and/or MF. Most general 4D flow parameters related to VC were increased in athletes and positive athletes compared to controls (p < 0.05). Gradient Boosting Machine (GBM) was the most effective model in sheet 2 of SVC, with the area under the curve values of 0.891, accuracy of 85.2%, sensitivity of 84.6%, and specificity of 85.4%. The top five predictors in descending order were as follows: net positive volume, forward volume, waist circumference, body weight, and body surface area. Physical activity can induce a high flow state in the vena cava. CR and/or MF may elevate the peak velocity and maximum pressure gradient of the IVC. This study successfully constructed a GBM model with high efficacy for predicting CR and/or MF. This model may provide guidance on the frequency of follow-up and the development of appropriate exercise plans for athletes.

Recirculatory Solvotaxis of a Nematic Droplet on Water Surface Enabling Miniaturization.

Self-organized contact line instabilities (CLI) of a macroscopic liquid crystal (LC) droplet can be an ingenious pathway to generate a large collection of miniaturized LC drops. For example, when a larger drop of volatile solvent (e.g., hexane) is dispensed near a smaller LC drop resting on a soft and slippery surface of a nonsolvent (e.g., water), unique self-organized locomotion in the form of a twin vortex has been observed within the droplets. This phenomenon is driven by the rapid counter diffusion of hexane and LC between the two droplets, resulting in the formation of a pair of vortices within the droplets before instigating a CLI at the three-phase contact line (TPCL) of the LC droplet. Initially, the higher Laplace pressure inside the LC droplet (PL,5CB) due to a net pressure gradient, PL,5CB > PL,Hex, drives the LC toward hexane. However, as the volatile solvent droplet shrinks due to rapid evaporation, a flow reversal happens owing to PL,5CB < PL,Hex. Subsequently, the diffusion of hexane into the LC droplet and its subsequent evaporation manifest a periodic oscillatory CLI expansion and retraction at the TPCL, which in turn form periodic finger-like structures. Following this, the fingers with a higher aspect ratio break into an array of miniaturized satellite LC droplets undergoing Rayleigh-Plateau instability (RPI). The observed deviation in the normalized satellite droplet spacing compared to theoretical value affirm the stabilizing influence of LC elasticity in such fingers, where λ and R5CB are experimentally calculated droplet spacing and 5CB droplet radius. Control experiments elucidate the specific contributions of capillary, drag, solutal Marangoni, and osmotic forces to the 5CB droplet locomotion phenomena. The experimentally and analytically consistent demonstration also supports and predicts pressure drop-induced droplet velocities as v ∼ t1.16.

Moment of momentum integral analysis of turbulent boundary layers with pressure gradient

Turbulent boundary layers on immersed objects can be significantly altered by the pressure gradients imposed by the flow outside the boundary layer. The interaction of turbulence and pressure gradients can lead to complex phenomena such as relaminarization, history effects and flow separation. The angular momentum integral (AMI) equation (Elnahhas &amp; Johnson, J. Fluid Mech., vol. 940, 2022, A36) is extended and applied to high-fidelity simulation datasets of non-zero pressure gradient turbulent boundary layers. The AMI equation provides an exact mathematical equation for quantifying how turbulence, free-stream pressure gradients and other effects alter the skin friction coefficient relative to a baseline laminar boundary layer solution. The datasets explored include flat-plate boundary layers with nearly constant adverse pressure gradients, a boundary layer over the suction surface of a two-dimensional NACA 4412 airfoil and flow over a two-dimensional Gaussian bump. Application of the AMI equation to these datasets maps out the similarities and differences in how boundary layers interact with favourable and adverse pressure gradients in various scenarios. Further, the fractional contribution of the pressure gradient to skin friction attenuation in adverse-pressure-gradient boundary layers appears in the AMI equation as a new Clauser-like parameter with some advantages for understanding similarities and differences related to upstream history effects. The results highlight the applicability of the integral-based analysis to provide quantitative, interpretable assessments of complex boundary layer physics.

End-procedural adherence to recommended hemodynamic targets does not improve the outcome of elective tips in cirrhotic patients.

In clinical practice, the reduction of porto-caval pressure gradient (PCPG) following trans-jugular intra-hepatic porto-systemic shunt (TIPS) does not always meet the recommendation of current guidance. We evaluated the impact of different degrees of PCPG reduction, measured at the end of an elective TIPS, on ascites control, recurrence of portal hypertension-related bleeding (PHRB) and survival. Cirrhotic patients receiving TIPS for refractory ascites (RA) or for the secondary prophylaxis of PHRB were consecutively enrolled. Reduction in PCPG was defined inadequate (IHR) in patients not achieving a PCPG <12mm Hg for both secondary prophylaxis of PHRB and RA, or a reduction of at least 50% only for PHRB. Four-hundred-fifteen patients were analyzed. An adequate hemodynamic response (AHR) was achieved in 66%. Fifty percent of patients received an under-dilated (≤7mm) endoprosthesis. No significant differences between patients with IHR and AHR were observed in rebleeding rate and ascites control, while overt hepatic encephalopathy was higher in AHR. Regardless of TIPS indication, survival was not significantly different between IHR and AHR, while advanced age and liver function before TIPS were significantly associated with a higher cumulative incidence of liver-related death. Notably, the cumulative incidence of liver-related mortality was higher in RA patients when AHR was defined as a post-TIPS PCPG <12mm Hg or a reduction ≥50%. AHR measured at the end of an elective TIPS may not be essential to define the eventual outcome, while a marked drop in PCPG could negatively affect the prognosis of patients with RA.

Identification of optimal portal pressure decrease to control ascites while minimizing hepatic encephalopathy after TIPS: A multicenter study.

Clinically-significant portal hypertension (CSPH) in liver cirrhosis patients can lead to refractory ascites. A transjugular-intrahepatic-portosystemic shunt (TIPS) treats CSPH but may cause overt hepatic encephalopathy (oHE). Our aim was to determine the optimal reduction of the portal pressure gradient (PPG) via TIPS to control ascites without raising oHE risk. This multicenter study screened 1509 patients from three European centers (Hannover, Vienna, Hamburg) undergoing TIPS-implantation between 2000-2023. Patients with TIPS-indications other than refractory ascites/hepatic hydrothorax, vascular-liver-disease, hepatocellular-carcinoma or insufficient PPG data were excluded. PPG was measured before and after TIPS insertion. Outcome data was assessed up to one year after TIPS-insertion. Analyses were conducted utilizing a modern machine leaning model, namely a competing-risk (CR) random survival forest (RSF), partial-dependence-plots (PDP) and CR-analyses with liver transplantation/death as competitors. The cohort was divided into a 60% derivation and 40% validation cohort. Overall, 729 patients (median MELD: 13 (IQR 10-16), 66% male, 23% oHE before TIPS) were analyzed. The derivation cohort comprised 438 and validation cohort 291 patients. The optimal PPG reduction, determined by maximally selected Grays-statistic and PDP of the RSF, was 60-80%. In this range, patients showed significantly fewer hepatic decompensations due to ascites (HDA) (sHR: 0.7 [0.52-0.96]) with similar oHE incidences (sHR: 0.92 [0.67-1.27]). The PPG range was confirmed in the validation cohort (HDA: sHR: 0.66 [0.46-0.96]; oHE: sHR: 0.89 [0.61-1.32]). A targeted PPG reduction of 60-80% showed significantly reduced HDA without increased oHE risk. Therefore, PPG reduction within this range could be a valid reduction target.

Precise Regulation of In Situ Exsolution Components of Nanoparticles for Constructing Active Interfaces toward Carbon Dioxide Reduction.

Metal nanocatalysts supported on oxide scaffolds have been widely used in energy storage and conversion reactions. So far, the main research is still focused on the growth, density, size, and activity enhancement of exsolved nanoparticles (NPs). However, the lack of precise regulation of the type and composition of NPs elements under reduction conditions has restricted the architectural development of in situ exsolution systems. Herein, we propose a strategy to attain a regulated distribution of exsolved transition metals (Cu, Ni, and Fe) on Sr2Fe1.2Ni0.2Cu0.2Mo0.4O6-δ medium-entropy perovskite oxides by varying the oxygen partial pressure (pO2) gradient in the mixture. At 800 °C, the unitary Cu, binary Cu-Ni, and ternary Cu-Ni-Fe NPs are exsolved as pO2 decreases from high to low. Combining experimental and theoretical simulations, we further corroborate that solid oxide electrolysis cells with ternary alloy clusters at the CNF@SFO interface exhibit superior CO2 electrolytic performance. Our results provide tailored strategies for nanostructures and nanointerfaces for studying metal oxide exsolution systems, including fuel electrode materials.

Numerical assessment of portal pressure gradient (PPG) based on clinically measured hepatic venous pressure gradient (HVPG) for liver cirrhosis patients.

Portal hypertension (PH) is the initial and main consequence of liver cirrhosis. Hepatic venous pressure gradient (HVPG) measurement has been widely used to estimate portal pressure gradient (PPG) and detect portal hypertension. However, some clinical studies have found poor correlation between HVPG and PPG, which may lead to the misdiagnosis of portal hypertension. In this study, we provided a method to evaluate patients' PPG based on clinically measured HVPG with computational fluid dynamics (CFD). Twenty-five patients who underwent HVPG measurement were recruit for analysis. Results show that HVPG significantly correlates with PPG (R=0.7499, P<0.0001), with an accuracy to distinguish clinically significant portal hypertension (CSPH) as high as 92%. However, PH severity classification was underestimated for 36% patients, especially for patients with hepatic venous collateral formation and presinusoidal portal vein occlusion. It is concluded that HVPG is a relatively reliable diagnostic method for PH when PPG cannot be directly measured. For patients who have clinical symptoms of PH but their HVPG are within a normal range, numerical evaluation of PPG with CFD is an excellent way for their diagnosis.

Artefacts due to putrefactive gas production - an overview.

Autolytic and putrefactive processes can cause considerable alterations to soft tissues and internal organs that may complicate forensic assessments. An overview was undertaken of the range of taphonomonic changes and processes that may result from postmortem putrefactive gas accumulation. The most commonly encountered phenomenon was purging of putrefactive fluids from the nose and mouth that was on occasion confused with bleeding from antemortem trauma. Much less common was putrefactive 'rigor mortis' where the limbs extend due to the accumulation of soft tissue and subcutaneous gas. This may sometimes be associated with alteration of the position of a body suggesting that it had been deliberately moved. Distension and stretching of the skin and subcutaneous tissues may cause recently sutured surgical incisions to dehisce, raising the possibility of inflicted incised wounds. Raised intra-abdominal pressures may cause diaphragmatic herniation of small intestine and has been associated with so-called 'coffin birth' where a fetus is expelled from the uterus after death due to pressure on the fundus. Gas accumulation on postmortem computed tomography examination may be confused with air embolism or the effects of trauma. All of these changes are the result of anaerobic bacterial action generating gases such as methane, carbon dioxide and hydrogen sulphide resulting in pressure gradients.