Changes In Capillary Pressure Research Articles

A semi-analytical model for fractured horizontal wells production considering imbibition during shut-in periods

After hydraulic fracturing in tight oil reservoirs, part of the fracturing fluid is retained in the formation. Therefore, it’s essential to investigate the pressure and saturation distributions during and after fracturing to further understand the impact of fluid loss on productivity. Concerning the capillary pressure, fracture propagation, and fracture volume changes, a semi-analytical model was established innovatively. Comparisons between the model’s calculations and actual measurements demonstrate a high level of agreement, validating the model’s accuracy. Furthermore, the impacts of capillary pressure, shut-in time, injection rate, initial reservoir pressure, and initial water saturation on actual production performance were investigated. The results show that the effect of capillary pressure on production in the tight reservoir cannot be ignored. A reasonable shut-in operation should be carried out according to the actual situation. A smaller injection rate should be selected to achieve a larger fracture length and imbibition area. The proportion of oil produced by capillary pressure decreases with the increase of initial pressure. The initial water saturation is positively correlated with oil production and negatively correlated with water production. The imbibition effect of shut-in operation is more obvious in tight reservoirs with low initial pressure and low water saturation.

An Integrated Approach for Saturation Modeling Using Hydraulic Flow Units: Examples from the Upper Messinian Reservoir

The Upper Messinian reservoirs located in the Salma Field of the Nile Delta area contain variable facies. The key reservoir interval of the Abu Madi Formation was deposited in fluvial to deltaic environments. These fine-grained facies form significant reservoir heterogeneity within the reservoir intervals. The main challenges in this study are reservoir characterizing and predicting the change in reservoir water saturation (SW) with time, while reservoir production life based on the change in reservoir capillary pressure (Pc). This work applies petrophysical analysis to enable the definition and calculation of the hydrocarbon reserves within the key reservoir units. Mapping of SW away from the wellbores within geo-models represents a significant challenge. The rock types and flow unit analysis indicate that the reservoir is dominated by four hydraulic flow units. HFU#1 represents the highest flow zone indicator (FZI) value. Core analysis has been completed to better understand the relationship between SW and the reservoir capillary pressure above the fluid contact and free water level (FWL), which is used to perform saturation height function (SHF) analysis. The calculated SW values that are obtained from logs are affected by formation water resistivity (Rw) and log true resistivity (RT), which are influenced by the volume of clay content and mud salinity. This study introduces an integrated approach, including evaluation of core measurements, well log analysis covering cored and non-cored intervals, neural analysis techniques (K-mode algorithm), and permeability prediction in non-cored intervals. The empirical formula was predicted for direct calculation of dynamic SW profiles and predicted within the reservoir above the FWL based on the change in reservoir pressure.

Trimetazidine in heart failure with preserved ejection fraction: a randomized controlled cross-over trial.

Impaired myocardial energy homeostasis plays an import role in the pathophysiology of heart failure with preserved ejection fraction (HFpEF). Left ventricular relaxation has a high energy demand, and left ventricular diastolic dysfunction has been related to impaired energy homeostasis. This study investigated whether trimetazidine, a fatty acid oxidation inhibitor, could improve myocardial energy homeostasis and consequently improve exercise haemodynamics in patients with HFpEF. The DoPING-HFpEF trial was a phase II single-centre, double-blind, placebo-controlled, randomized cross-over trial. Patients were randomized to trimetazidine treatment or placebo for 3months and switched after a 2-week wash-out period. The primary endpoint was change in pulmonary capillary wedge pressure, measured with right heart catheterization at multiple stages of bicycling exercise. Secondary endpoint was change in myocardial phosphocreatine/adenosine triphosphate, an index of the myocardial energy status, measured with phosphorus-31 magnetic resonance spectroscopy. The study included 25 patients (10/15 males/females; mean (standard deviation) age, 66 (10) years; body mass index, 29.8 (4.5) kg/m2 ); with the diagnosis of HFpEF confirmed with (exercise) right heart catheterization either before or during the trial. There was no effect of trimetazidine on the primary outcome pulmonary capillary wedge pressure at multiple levels of exercise (mean change 0 [95% confidence interval, 95% CI -2, 2] mmHg over multiple levels of exercise, P=0.60). Myocardial phosphocreatine/adenosine triphosphate in the trimetazidine arm was similar to placebo (1.08 [0.76, 1.76] vs. 1.30 [0.95, 1.86], P=0.08). There was no change by trimetazidine compared with placebo in the exploratory parameters: 6-min walking distance (mean change of -6 [95% CI -18, 7] m vs. -5 [95% CI -22, 22] m, respectively, P=0.93), N-terminal pro-B-type natriuretic peptide (5 (-156, 166) ng/L vs. -13 (-172, 147) ng/L, P=0.70), overall quality-of-life (KCCQ and EQ-5D-5L, P=0.78 and P=0.51, respectively), parameters for diastolic function measured with echocardiography and cardiac magnetic resonance, or metabolic parameters. Trimetazidine did not improve myocardial energy homeostasis and did not improve exercise haemodynamics in patients with HFpEF.

Capillary carbon dioxide tension increases in hospital staff wearing filtering facepiece masks: a prospective crossover study.

The COVID-19 pandemic has changed worldwide hygiene practices. In particular, the use of filtering face piece (FFP) masks markedly increased. Concerns have been raised regarding possible negative respiratory effects of wearing FFP masks. The aim of this study was to investigate gas exchange and subjective breathing effort in hospital personnel wearing FFP2 or FFP3 masks. In this prospective, single-centre, crossover study, 200 hospital workers were assigned to alternately wear FFP2 or FFP3 masks for 1 h during routine activities. Capillary blood gas analysis was performed to evaluate gas exchange while wearing the FFP masks. The primary end-point was the change in capillary partial pressure of carbon dioxide (PcCO2). In addition, capillary partial pressure of oxygen (PcO2), respiratory rate and subjective breathing effort were assessed at the end of each hour. Changes between time points and study groups were estimated using univariate and multivariate models. PcCO2 increased from 36.8±3.5 to 37.2±3.3 mmHg (p=0.047) and 37.4±3.2 mmHg (p=0.003) in individuals wearing FFP2 or FFP3 masks, respectively. Age (p=0.021) and male sex (p<0.001) were significantly associated with increased PcCO2. Similarly, the PcO2 increased from 70.7±8.4 to 73.4±8.8 mmHg (p<0.001) and 72.8±8.5 mmHg (p=0.004) in individuals wearing FFP2 or FFP3 masks, respectively. Respiratory rate and subjective breathing effort increased significantly while wearing FFP2 and FFP3 masks (p<0.001 for all analyses). The order of wearing FFP2 or FFP3 masks did not significantly affect the results. An hour of wearing FFP2 or FFP3 masks increased PcCO2 values, respiratory rate and subjective breathing effort in healthcare personnel performing routine activities.

Extensive Epipericardial Fat Necrosis in a Case of Metastatic Adenocarcinoma of Lung

Epipericardial fat necrosis is an uncommon benign and self-limiting condition that leads patients to the emergency department owing to the onset of acute pleuritic chest pain. Fat necrosis in adipose tissue can occur at various sites: in the breast and subcutaneous fat after trauma, peripancreatic fat in pancreatitis, and epiploicappendagitis.[1,2] Rarely, it may occur within the epipericardial fat. Since the first description by Jackson et al.,[3] only 35 cases have been published in the English literature, and extensive epipericardial fat necrosis (EFN) is currently described as an extremely rare disease.[4] The aetiology of EFN remains unknown, but some theories have been proposed to explain its origin. Acute torsion of a vascular pedicle is described in some cases, although the presence of a vascular pedicle has been described in only two patients who underwent surgery.[4] Furthermore, increased intrathoracic pressure due to heavy lifting or Valsalva's manoeuvre might trigger rapid changes in capillary pressure, leading to haemorrhagic necrosis, especially if pre-existing structural abnormalities of the adipose tissue, such as lipoma, hamartoma or lipomatosis, are present.[5] Both males and females are affected, and neither age predilections nor pre-disposing factors have been described.[4]

Abstract 12368: Results From the DoPING-HFpEF Trial: A Double Blind, Placebo-Controlled Randomized Cross-Over Trial Investigating Trimetazidine in Heart Failure With Preserved Ejection Fraction

Introduction: Due to mitochondrial dysfunction, cardiac energy homeostasis is compromised in heart failure with preserved ejection fraction. As left ventricular relaxation is an active and energy consuming process there is a clear relationship between the impaired cardiac metabolism and diastolic dysfunction. Here, we investigate whether trimetazidine, a fatty acid oxidation inhibitor, can improve cardiac energy homeostasis and consequently improve diastolic function. Methods: This was a single-center, double-blind, placebo-controlled randomized cross-over trial consisting of two treatment periods of three months with a 2 week washout period in between. Patients (N=25) were treated with 20mg trimetazidine or placebo t.i.d. or b.i.d. (based on kidney function). The primary endpoint was change in pulmonary capillary wedge pressure (PCWP) measured with right heart catheterization at multiple stages of exercise. Secondary endpoint was change in phosphocreatine (PCr)/adenosine triphosphate (ATP) ratio, an index of the myocardial energy status, measured with phosphorus-31 magnetic resonance (MR) spectroscopy. Results: All included patients had invasively proven heart failure with preserved ejection fraction. There was no effect on the primary outcome PCWP at multiple levels of exercise ( P =0.60). Myocardial PCr/ATP in the trimetazidine arm was similar to placebo ( P =0.08). There was no change by trimetazidine in the exploratory parameters 6-minute walking distance, NT-proBNP, overall quality of life, or other parameters for diastolic function measured with echocardiography and cardiac MR, or additional metabolic parameters. Trimetazidine plasma level are currently being assessed and will be available at the moment of presentation. Conclusion: Trimetazidine did not improve diastolic function or myocardial energy homeostasis in patients with HFpEF. Disclosure of unlabeled use: Trimetazidine was not labeled for use in HFpEF.

Trimetazidine in heart failure with preserved ejection fracton: a randomized, double-blind cross-over trial

Abstract Introduction Impaired myocardial mitochondrial function plays an import role in the pathophysiology of heart failure with preserved ejection fraction (HFpEF). Left ventricular relaxation has a high energy demand, and there is evidence indicative of a causal relationship between observed impaired energy homeostasis and diastolic dysfunction. Improvement of mitochondrial function with metabolism-modulating drugs may be a promising novel therapeutic approach in HFpEF. Trimetazidine – a fatty acid oxidation inhibitor – shifts mitochondrial metabolism towards glucose oxidation, which results in higher mitochondrial oxygen efficiency. In this study we investigated whether trimetazidine improves diastolic function during exercise in HFpEF by improving the myocardial energy homeostasis. Methods The DoPING-HFpEF trial was a phase II single-center, double-blind, placebo-controlled, randomized cross-over trial. The study consisted of two treatment periods of three months separated by a 2-week wash-out period (Figure 1). Patients were treated with placebo or trimetazidine three times a day (or twice daily in case of an impaired kidney function). The primary endpoint was change in pulmonary capillary wedge pressure (PCWP) measured with right heart catheterization at multiple stages of exercise. Secondary endpoint was change in phosphocreatine (PCr)/adenosine triphosphate (ATP) ratio, an index of the myocardial energy status, measured with phosphorus-31 magnetic resonance (MR) spectroscopy. Additional exploratory endpoints were 6-minute-walking-distance, diastolic and systolic parameters measured with echocardiography or cardiac MR, NT-proBNP levels, and quality of life. Results Twenty-five HFpEF patients were included and completed the trial, 80% of which were included based on previously established elevated (exercise) PCWP, and 20% were included based on diastolic dysfunction grade ≥II on echocardiography and elevated NT-proBNP levels. There was no effect on the primary outcome PCWP at multiple levels of exercise, with an average change in PCWP of 0±4 (SD) mmHg (Figure 2A, P=0.97). Myocardial PCr/ATP in the trimetazidine arm was similar to placebo (Figure 2B, P=0.08). There was no change by trimetazidine in the exploratory parameters 6-minute walking distance, NT-proBNP, overall quality of life, or other parameters for diastolic function measured with echocardiography and cardiac MR. There was no indication of period or cross over effect. Conclusion Trimetazidine did not improve diastolic function or myocardial energy homeostasis in patients with HFpEF. Funding Acknowledgement Type of funding sources: Foundation. Main funding source(s): Dutch Heart Foundation (DHF) and “Out-of-the-Box” grant from the Amsterdam Cardiovascular Sciences (ACS) Institute, Amsterdam, The Netherlands.

Nano-scale multicomponent hydrocarbon thermodynamic transport mechanisms in shale oil reservoir

Hydrocarbon mass transport in nanoporous media notably differs from that in traditional micro-scale porous media due to strong solid-fluid interaction in nanoscale confined pore space. Accurate prediction of hydrocarbon thermodynamic transport in nanoporous shale must consider the bound water distribution pattern, fluid occurrence in dual-wet pores (organic and inorganic), thermodynamic phase equilibrium, boundary slippage and rheological property. So far, there is no such a model that incorporates the above mentioned factors into assessing the multicomponent hydrocarbon mass transport in nanoporous shale. In this work, we propose a pore network based multicomponent hydrocarbon mass transport model considering above mentioned factors and the multicomponent hydrocarbon thermodynamic transport mechanisms are elucidated in detail. The bound water film stability and induced capillary condensation are first analyzed according to Kelvin equation and the extended DLVO theory. A thermodynamic phase equilibrium-fluid occurrence coupling model is further developed considering the oil-gas capillary pressure change with oil saturation on pore network model (PNM). The multicomponent hydrocarbon single pore transport model is derived considering boundary slippage, adsorption layer thickness and fluid rheology and is extended to PNM transport simulation. The multicomponent hydrocarbon permeability variations at different pressure, pore size, relative humidity and total organic carbon (TOC) are analyzed in detail. The predicted hydrocarbon flux change with pressure gradient matches well with the previous observed trend in the laboratory experiments. Study results reveal that the multicomponent hydrocarbon exhibits non-linear transport behavior determined by the fluid rheology and the threshold pressure gradient for hydrocarbon starting to flow is mutually controlled by the yield stress and pore size.

A new four stage model of capillary pressure in early age concrete: Insights from high capacity tensiometers

Capillary pressure is frequently measured to evaluate the shrinkage performance of concrete but has been limited to pressures <100 kPa preventing a better understanding of the early age factors affecting concrete durability. In this study, high capacity tensiometers (HCTs) were employed for the first time to investigate the behavior of early age concrete. The evolution of capillary pressure in Self-Consolidating Concrete (SCC) with and without shrinkage reducing admixture was evaluated. The results demonstrate that HCTs are capable of measuring capillary pressure beyond 1500 kPa. This transformative new record of capillary pressure behavior has enabled the development of a model for the capillary pressure in early age concrete correlated to water evaporation, self-desiccation, setting time, temperature, and hydration processes. This ability to quantify real-time capillary pressure change in concrete generates important implications for optimizing the commercial durability of SCC and for understanding the link between early age concrete processes and resultant mechanical performance.

Ion channels and channelopathies in glomeruli.

An essential step in renal function entails the formation of an ultrafiltrate that is delivered to the renal tubules for subsequent processing. This process, known as glomerular filtration, is controlled by intrinsic regulatory systems and by paracrine, neuronal, and endocrine signals that converge onto glomerular cells. In addition, the characteristics of glomerular fluid flow, such as the glomerular filtration rate and the glomerular filtration fraction, play an important role in determining blood flow to the rest of the kidney. Consequently, disease processes that initially affect glomeruli are the most likely to lead to end-stage kidney failure. The cells that comprise the glomerular filter, especially podocytes and mesangial cells, express many different types of ion channels that regulate intrinsic aspects of cell function and cellular responses to the local environment, such as changes in glomerular capillary pressure. Dysregulation of glomerular ion channels, such as changes in TRPC6, can lead to devastating glomerular diseases, and a number of channels, including TRPC6, TRPC5, and various ionotropic receptors, are promising targets for drug development. This review discusses glomerular structure and glomerular disease processes. It also describes the types of plasma membrane ion channels that have been identified in glomerular cells, the physiological and pathophysiological contexts in which they operate, and the pathways by which they are regulated and dysregulated. The contributions of these channels to glomerular disease processes, such as focal segmental glomerulosclerosis (FSGS) and diabetic nephropathy, as well as the development of drugs that target these channels are also discussed.

Estimation of Changes in Intracardiac Hemodynamics Using Wearable Seismocardiography and Machine Learning in Patients With Heart Failure: A Feasibility Study.

Tracking changes in hemodynamic congestion and the consequent proactive readjustment of treatment has shown efficacy in reducing hospitalizations for patients with heart failure (HF). However, the cost-prohibitive nature of these invasive sensing systems precludes their usage in the large patient population affected by HF. The objective of this research is to estimate the changes in pulmonary artery mean pressure (PAM) and pulmonary capillary wedge pressure (PCWP) following vasodilator infusion during right heart catheterization (RHC), using changes in simultaneously recorded wearable seismocardiogram (SCG) signals captured with a small wearable patch. A total of 20 patients with HF (20% women, median age 55 (interquartile range (IQR), 44-64) years, ejection fraction 24 (IQR, 16-43)) were fitted with a wearable sensing patch and underwent RHC with vasodilator challenge. We divided the dataset randomly into a training-testing set (n = 15) and a separate validation set (n = 5). We developed globalized (population) regression models to estimate changes in PAM and PCWP from the changes in simultaneously recorded SCG. The regression model estimated both pressures with good accuracies: root-mean-square-error (RMSE) of 2.5 mmHg and R2 of 0.83 for estimating changes in PAM, and RMSE of 1.9 mmHg and R2 of 0.93 for estimating changes in PCWP for the training-testing set, and RMSE of 2.7 mmHg and R2 of 0.81 for estimating changes in PAM, and RMSE of 2.9 mmHg and R2 of 0.95 for estimating changes in PCWP for the validation set respectively. Changes in wearable SCG signals may be used to track acute changes in intracardiac hemodynamics in patients with HF. This method holds promise in tracking longitudinal changes in hemodynamic congestion in hemodynamically-guided remote home monitoring and treatment for patients with HF.

CO2 sequestration in sandstone reservoirs: How does reactive flow alter trapping mechanisms?

Numerous studies have attempted to assess the possible changes in the petrophysical parameters of sandstone reservoirs for the geological storage of CO2. However, the results have been highly variable and hardly conclusive, highlighting mineral alteration, precipitation, dissolution, and fine migration as the main drivers of changes in porosity, permeability, and surface wettability. In this paper, a series of systematic experimental studies were carried out on the Berea sandstone samples to carefully analyse the changes in porosity, relative permeability, capillary pressure, and surface wettability after CO2 treatment. The results obtained indicated that porosity increased in the samples due to dissolution of minerals (calcite and clay) and there was no sign of pore throat closure due to mineral precipitation. It was found that the surface wettability can be shifted towards a CO2 wet system, probably because of calcite precipitation and clay dissolution or reduction in the hydrophilicity of quartz, leading to a decrease in capillary entry pressure. It appears that the mineral and capillary trapping in sandstone make it a suitable storage site for CO2, but that require further research to fully understand the changes posed by mineral dissolution in the long term.

Capillary Pressure Behavior of CO2 - Shale System at Elevated Temperatures

In this study, changes in capillary entry pressure of shale when interacting with CO2, under different temperatures have been investigated. The combined impact of temperature and petrophysical properties of shale (water content, water activity, permeability and porosity) on capillary entry pressure was addressed. Pressure breakthrough measurements were used to evaluate the minimum entry pressure of CO2 through shale. A heavy-duty oven was used to vary the temperature in order to investigate the impact of temperature on CO2 capillary entry pressure through shale. Results showed that capillary entry pressure of shale when interacting with CO2 was highly affected by temperature. Higher temperatures decreased capillary entry pressure of shale. We believe that pore dilation, where pore throat size expands due to the application of heat, may have caused this decrease in capillary entry pressure. However, in some cases higher temperature activated clay swelling that may have caused an apparent decrease in pore throat radii of shale which translated into higher capillary entry pressure. Results also showed that there exists no distinct relationship between petrophysical properties of shale and its measured capillary entry pressure when interacting with CO2 at different temperatures. Heat could alter pore throat radii and cause pore dilation which may alter measured capillary entry pressure. Interfacial tension decreases with increasing temperature and that can be attributed to the weakening of intermolecular forces at the two immiscible fluids interface. Swelling of clay could be related to temperature-induced transition from passive to an active clay.

Haemodynamic changes of interatrial shunting devices for heart failure: a systematic review and meta-analysis.

AimsTo assess the efficacy and safety, primarily in relation to the haemodynamic effects, of interatrial shunting devices (ISD) for the treatment of heart failure (HF), we conducted a systematic review and a meta‐analysis.Methods and resultsWe used the MEDLINE, Cochrane Library, Embase, and PubMed databases to identify clinical studies (published to 4 August 2021) that evaluated the effect of ISD on HF. The primary endpoint was defined as changes in pulmonary capillary wedge pressure (PCWP). Secondary endpoints included (i) other haemodynamic indexes, including cardiac output (CO), right atrial pressure (RAP), and mean pulmonary artery pressure (mPAP) by right heart catheterization, and (ii) change from baseline in 6 min walk distance (6MWD). After a literature search and detailed evaluation, six trials enrolling a total of 203 individuals were included in the quantitative analysis. Pooled analyses showed that after ISD implantation, PCWP decreased by a mean 3.10 mmHg [95% confidence interval (CI) −4.56 to −1.64; I 2 = 0%; P < 0.0001]. Overall, CO increased by 0.77 L/min (95% CI 0.02 to 1.52; P = 0.04; I 2 = 82%), but there were no significant changes in RAP or mPAP. The mean 6MWD increased by 32.33 m (95% CI 10.74 to 53.92; P = 0.003; I 2 = 0) after ISD implantation.ConclusionsInteratrial shunting device can effectively reduce PCWP, increase CO and 6MWD, and has no obvious adverse effects on the right heart and pulmonary pressure. Studies with larger sample size and longer follow‐up time are needed for further verification.

Wettability alteration and improved oil recovery in unconventional resources

The ultimate recovery factor in tight and shale resources is limited and is usually in the range of 5–10%. Although high-intensity fracturing and refracturing can increase recovery, an enormous amount of oil will remain in place, hence the desirability of enhanced oil recovery methods. Many of the shale reservoirs are oil-wet with negligible water uptake. By altering the wettability, water can spontaneously imbibe into the formation matrix, creating a counter-current flow that forces the oil out. Here, we assess the likelihood of increased oil recovery by modifying the fracturing-fluid composition (salinity and ion concentration) that transforms the formation wettability into a more water-wet state.Oil wetting of tight formations is usually controlled by the adhesion of oil droplets on the surface of clay minerals. When clay minerals are not predominant, the oil attached to carbonate minerals can significantly control rock wettability. In this study, we first identify the primary reactions that define the initial wettability of the rock depending on the formation mineralogy, formation water composition, and oil type. Second, we build a geochemical model considering the surface complexation of various minerals to mimic the wettability state of the reservoir. Third, we validate our method on zeta-potential, contact angle, and imbibition data from a previously published study using different fluids with different salinities. Finally, we present a mechanistic approach to model the wettability-alteration impact on spontaneous imbibition and compute the incremental oil recovery contributed by different fracturing fluid compositions.Based on the studied case, the oil adhesion to clay can be reduced by tuning the fracturing fluid salinity. The ionic concentrations of 2.5 wt % of NaCl and 5.0 wt % of CaCl2 induced the smallest contact angles of 44.7 and 51.2°. We observe that further brine dilution increases the contact angle. For example, distilled water shows the most oil-wet condition with a contact angle to 93.4°. We argue that the main factors that maximize water wetting for the reported optimum salinities are the contrast in the rock and oil surface potential and the sodium concentration. Spontaneous-imbibition simulations indicate that the low salinity fluids promote a change in water-oil capillary pressure, leading to increased water uptake in the cores and improved oil recovery compared to distilled water. The agreement between the developed model and experimental data implies that the wettability in shale and tight formations can be quantitatively predicted and regulated.

Randomized Controlled Trial of the Hemodynamic Effects of Empagliflozin in Patients With Type 2 Diabetes at High Cardiovascular Risk: The SIMPLE Trial.

Treatment with the sodium-glucose cotransporter 2 inhibitor (SGLT-2i) empagliflozin significantly reduces cardiovascular events in patients with type 2 diabetes (T2D); however, the mechanisms behind the reduction in cardiovascular (CV) events are unknown. We investigated whether SGLT-2i treatment affected central hemodynamics during rest and exercise in 34 patients with diabetes in this investigator-initiated, randomized, placebo-controlled, double-blinded trial. The primary end point was change in pulmonary capillary wedge pressure (PCWP) at a submaximal ergometer workload (25 W) after 13 weeks of SGLT-2i treatment (25 mg once daily) compared with placebo. Secondary end points included changes in resting hemodynamics. Baseline and follow-up hemodynamic assessments were performed at rest, submaximal exercise (25 W), and peak exercise using right heart catheterization. Treatment with empagliflozin for 13 weeks in patients with T2D at high CV risk did not reduce left heart filling pressure more than placebo at submaximal exercise. At rest, we observed that empagliflozin reduced PCWP at a magnitude of clinical significance.

Experimental and Numerical Study of the Drying Process of a Consolidated Clay Soil

The clay soil is composed of solid skeleton and porous and can be studied in the framework of porous media. During the drying process, the initial saturated clay soil deforms mainly due to the changes of water content and capillary pressure. With the further increase in capillary pressure, the soil cracks. In fact, the deformation and the stress in clay soil are tightly related with the water content and capillary pressure. Therefore, it is of great interest to understand the changes in capillary pressure and water content within the clay soil during the drying process. However, it is difficult to obtain these field variables by experiments alone. Therefore, the numerical simulation could be good choice for deeper understanding of the dry process in clay soil. In current research, the combined numerical simulation and laboratory experiments research are conducted; the numerical results are compared with the laboratory observation. This research is the basis for the further study of the cracking process of clay soil due to drying.

Effects of methane hydrates on two-phase relative permeability in sandstone: Numerical simulation of laboratory experiments

To identify the challenges and limitations in measuring and modelling gas relative permeability in hydrate bearing sandstone, we simulate a series of experiments. Experimental and numerical results are used to examine the amount of hydrates formed as well as how the flow of gas is affected by the hydrate formation. The reservoir simulator TOUGH+HYDRATE was used. The system is represented numerically in both 1-dimensional and 2-dimensional grids. The 1-dimensional simulations are used to check the system consistency by keeping track of the amount of hydrates that are formed, given the initial and boundary conditions. The 2-dimensional simulations are used to measure the effects of heterogeneity in the distribution of hydrates, and its impact on both relative permeability and capillary pressure. The results reveal complexities when comparing experimental and simulated permeability in hydrate-bearing systems. The results from the 1-dimensional calculations show that most experiments have not been able to form the amount of hydrates that is theoretically possible by the initial mix of brine and gas. This indicates that early growth of hydrates can limit mass transfer to inner parts of the core shielding the system for further nucleation. This is supported by the 2-dimensional simulations. These show how a heterogeneous pattern of hydrates can limit fluid flow by (a) reducing the intrinsic permeability, (b) scaling down gas relative permeability, and (c) and scaling up capillary entry pressure of portions of the core. Although these effects do not fully explain the experimental results, the results provide insight to hydrate induced flow restrictions and how these can affect experimental result. • Comparison between simulation and experimental measurements of gas relative permeability of methane hydrate-bearing sandstone. • Heterogeneous formation of hydrates can affect experimental measurements of flow through porous media. • Characterization of hydrate heterogeneity is essential to model effective phase permeability. • Modelled hydrate-driven changes in both permeability and capillary pressure results in a reduction of effective fluid.

The mechanisms of anti-icing properties degradation for slippery liquid-infused porous surfaces under shear stresses

HypothesisLoss of anti-icing properties of slippery liquid-infused porous surfaces (SLIPS) in conditions of repetitive shear stresses is the intrinsic process related to peculiarities of SLIPS structure. ExperimentsThe study of the evolution of the ice adhesion strength to superhydrophobic surfaces (SHS) and SLIPS during repetitive icing/de-icing cycles measured by a centrifugal method was supplemented with the estimation of change in capillary pressure inside the pores, and SEM analysis of the effect of multiple ice detachments on surface morphology. FindingsObtained data indicated that although for freshly prepared SLIPS, the ice shear adhesion strength at −25 °C was several times lower than for SHS, repetitive icing-deicing cycles resulted in dramatic SLIPS degradation. In contrast, SHS showed weak degradation at least during 50 cycles. Additional to the depletion of an impregnating oil layer, other mechanisms of SLIPS degradation were hypothesized and tested. It was shown that lower capillary pressure required to displace air by water from the surface texture for SLIPSs compared to SHSs resulted in deeper water/ice penetration inside the grooves. The accelerated destruction of the mechanical texture caused by the Rehbinder effect constitutes another mechanism of SLIPSs degradation.

Remobilization of LNAPL in unsaturated porous media subject to freeze-thaw cycles using modified light transmission visualization technique

The frequent use of light non-aqueous phase liquids (LNAPLs) in cold regions creates serious risks of soil and groundwater contamination. However, the subsurface remobilization behaviors of LNAPL in freezing and thawing unsaturated porous media are not well understood. The light transmission visualization (LTV) technique, which be previously used in two-phase system (water–air or water-NAPL), is modified to quantify LNAPL in three-(water–air-LNAPL) or four-phase (water–ice-air-LNAPL) systems during freezing and thawing. The pattern of LNAPL remobilization was observed in a two-dimensional flow chamber filled with unsaturated porous media subject to freeze–thaw cycles (FTCs) using the modified LTV technique. It is shown that LNAPL remobilization mainly occurs in the direction of the freezing front and horizontal with the number of FTCs. Meanwhile, LNAPL in the area below the freezing front is promoted to remigrate downward during freezing and the opposite direction during thawing. The analysis suggests that LNAPL remobilization is caused by a combination of freezing-induced pressure and changes in capillary pressure controlled by water migration, rather than through microcracks in the frozen porous media. The proposed modified LTV technique shows great promise for investigating LNAPL transport and distribution in freezing (unfreezing) unsaturated porous media that is non-destructive. The study offers a scientific basis for the prediction of the subsurface behavior of LNAPL at contaminated sites in widely distributed cold regions.