Pressure Condition Research Articles

Novel Roles of Catalysts in Producing High-Purity High-Pressure Hydrogen from Sodium Borohydride.

Hydrogen has received enormous attention as a clean fuel with its high specific energy (HHV=142 MJ kg-1). To apply hydrogen as a practically available energy vector, the direct production of high-pressure hydrogen with high purity is pivotal as it allows for circumventing the mechanical compression process. Recently, the concept of utilizing sodium borohydride (SBH) dehydrogenation as a chemical compressor that can generate high-pressure hydrogen gas was demonstrated by adopting formic acid as an acid catalyst. However, the presence of impurities (e.g., CO, CO2) in the final gas product requires an alternative method to enhance the use of SBH as a chemical compressor. Here, we highlighted the feasibility of producing high-purity, high-pressure hydrogen gas from the SBH dehydrogenation with and without Co-based catalysts. The scrutiny behind the thermodynamics and kinetics of the SBH dehydrogenation was conducted under the elevated pressure condition. As a result, the dual roles of the catalysts as proton collectors and heat sources were revealed, both of which are essential for improving hydrogen production efficiency. We hope that our research stimulates subsequent research that pave the way to exploit hydrogen as an energy vector and achieve a more sustainable future society.

Solvent‐free synthesis of medium chain triacylglycerols by esterification of capric, caprylic acids with 1, 3‐specific and non‐specific lipases

AbstractMedium chain triacylglycerols (MCTs) are used as a functional oil in various food and pharmaceutical formulations because of their numerous health benefits and physical properties. Enzymatic esterification of glycerol with caprylic (C8:0) and capric acids (C10:0) in a molar ratio of 1:3.5 [50% (C8:0) and 50% (C10:0)] was carried out for the solvent free synthesis of MCTs using 5% (w/w) 1,3 specific lipase, Lipozyme RM IM and non‐specific lipase, Novozym 435 in the presence of molecular sieves (10%) and low pressure conditions (50 and 150 mbar) at 50°C. Novozym 435 was more effective in the esterification reaction under 50 mbar reduced pressure, achieving ~54.74% triacylglycerol formation in 6 h, compared to Lipozyme RMIM, which achieved ~31.25% under the same conditions. Further reactions with Novozym 435 for 24 h showed that the maximum formation of MCTs occurred at 20 h (86.46 ± 3%), after which the reaction reached equilibrium. When 50 mbar was used, the formation of triacylglycerols enhanced 13 times compared with the results obtained at atmospheric pressure condition. Chemical characterization of the final MCTs confirmed the formation of four triacylglycerol species (TAG (8:0/8:0/8:0), TAG (8:0/8:0/10:0), TAG (8:0/10:0/10:0), and TAG (10:0/10:0/10:0) with LC–MS and NMR analysis. The melting and crystallization points of the synthesized oil was found to be −3.47°C and −23.48°C, respectively. Our findings contribute to developing a green process for synthesizing MCTs using two different fatty acids. The final product can be used as a nutraceutical oil or as an ingredient to enhance the food's physical properties.

Relativistic model for anisotropic compact stars in embedding class-I spacetime

In the present article, we introduce a completely new regular model for static, spherically symmetric celestial fluid spheres in embedding class I spacetime. In this regard, needfully, we propose a new suitable metric potential e λ(r) to generate the present model. The various analyses on energy density, pressure, anisotropic factor, mass, compactness parameter, redshift, and energy condition make sure the model is physically viable on the ground of model stars Vela X-1, Cen X-3, SMC X-4, and LMC X-4. The reported solutions also respect the equilibrium state by satisfying the Tolman–Oppenheimer–Volkoff (TOV) equation and ensure stability by satisfying the causality condition, condition on the adiabatic index, and Harrison–Zeldovich–Novikov condition. The generated M − R graph matches the ranges of masses and radii for the model compact stars. Additionally, this study provides estimates of the moment of inertia based on the I − M graph.

Identification of novel hypertension biomarkers using explainable AI and metabolomics

BackgroundThe global incidence of hypertension, a condition of elevated blood pressure, is rising alarmingly. According to the World Health Organization’s Qatar Hypertension Profile for 2023, around 33% of adults are affected by hypertension. This is a significant public health concern that can lead to serious health complications if left untreated. Metabolic dysfunction is a primary cause of hypertension. By studying key biomarkers, we can discover new treatments to improve the lives of those with high blood pressure.AimsThis study aims to use explainable artificial intelligence (XAI) to interpret novel metabolite biosignatures linked to hypertension in Qatari Population.MethodsThe study utilized liquid chromatography-mass spectrometry (LC/MS) method to profile metabolites from biosamples of Qatari nationals diagnosed with stage 1 hypertension (n = 224) and controls (n = 554). Metabolon platform was used for the annotation of raw metabolite data generated during the process. A comprehensive series of analytical procedures, including data trimming, imputation, undersampling, feature selection, and biomarker discovery through explainable AI (XAI) models, were meticulously executed to ensure the accuracy and reliability of the results.ResultsElevated Vanillylmandelic acid (VMA) levels are markedly associated with stage 1 hypertension compared to controls. Glycerophosphorylcholine (GPC), N-Stearoylsphingosine (d18:1/18:0)*, and glycine are critical metabolites for accurate hypertension prediction. The light gradient boosting model yielded superior results, underscoring the potential of our research in enhancing hypertension diagnosis and treatment. The model’s classification metrics: accuracy (78.13%), precision (78.13%), recall (78.13%), F1-score (78.13%), and AUROC (83.88%) affirm its efficacy. SHapley Additive exPlanations (SHAP) further elucidate the metabolite markers, providing a deeper understanding of the disease’s pathology.ConclusionThis study identified novel metabolite biomarkers for precise hypertension diagnosis using XAI, enhancing early detection and intervention in the Qatari population.

Experimental Study on Liquid Jet Trajectory in Cross Flow of Swirling Air at Elevated Pressure Condition

Abstract Motivated by fuel atomization applications in gas turbine combustors, this paper presents an experimental examination of liquid jet trajectory and spray dynamics in crossflow of swirling air, at elevated pressure conditions. The study was conducted within an annular passage and was focused on momentum flux ratio and swirl number as the main parameters. The momentum flux ratio was varied from 2 to 25 through incremental adjustments to the liquid injection velocity and the swirl number values of 0.42 and 0.74 were used, representing typical gas turbine fuel atomization conditions. Jet trajectories were captured by imaging the three-dimensional helical path traced by the liquid jet using two mutually perpendicular optical windows. Radial penetration was quantified by solving the equations of a helix. The key findings revealed that radial penetration of the liquid jet is larger for higher momentum flux ratios and is influenced by the helical arc length. Notably, the radial penetration observed at low momentum flux ratios was larger for crossflow with lower swirl number and the radial penetration observed at high momentum flux ratios was more for crossflows with higher swirl number. In comparison to the spray characteristics in swirling crossflows at atmospheric pressure, condition of elevated gaseous pressure resulted in lower radial penetration, jet spread and jet area. Jet trajectory correlations for elevated pressure conditions are additionally presented, developed using curve fitting to the experimental data, which will be useful to the industry for estimation of spray trajectory in swirling crossflows at high pressure conditions.

Анализ эффективности и безопасности применения CFTR-модулятора лумакафтор/ивакафтор у пациентов с муковисцидозом в разных возрастных группах

Russia’s first registered CFTR-modulator lumacaftor/ivacaftor was developed for patients with cystic fibrosis (CF) with the F508del/F508del genotype. The purpose of this research was to study the efficacy and safety of lumacaftor/ivacaftor therapy in different age groups. Materials and methods used: the data of homozygotes for F508del aged 2 to 18 y/o in the Russian CF Patient Registry who had been treated with lumacaftor/ivacaftor were analyzed. The effectiveness of therapy was evaluated in 3 age groups based on examination data, nutritional status, spirometry, sweat test at the start of therapy and after 12 months. In order to assess the safety, examination data, assessment of adverse events (AE), blood biochemical parameters, blood pressure and lens condition were taken into account in 334 pediatric patients in the first month of therapy and in 180 after 12 months. Results: decrease in sweat conductivity was noted in three age groups (p<0.001), only in the 2 to 6 y/o age group were negative values obtained in 6.8%. An increase in BMI was observed in the 6 to 12 y/o and 12 to 18 y/o age groups (р<0.001) whilst an improvement in FVC was observed only in the 12 to 18 y/o age group (p=0.015). Changes in biochemical parameters were statistically significant, both downward and upward, only in the age groups of 6 to 12 y/o and 12 to 18 y/o, changing not significantly. Withdrawal of the drug was required in only a single patient with a persistent increase in transaminase level. Fluctuations in blood pressure occurred within the normal age limits. Frequency of AE was comparable with the results of other studies, it was noted at the start in all groups and after 12 months more often in the age group of 12 to 18 y/o. The best tolerance was noted in the age group of 2 to 6 y/o. Conclusion: for the first time, the efficacy and tolerability of lumacaftor/ivacaftor in patients with CF in Russia was studied against the age aspect according to the 2022-2024 Registry. In the 2 to 6 y/o age group, the achievement of normal sweat test values and the lowest number of adverse reactions were noted, while in the 12 to 18 y/o age group, the positive dynamics were noted for a greater number of indicators, incl. an increase in FVC.

The Relationship Between Family Social Support and Dietary Compliance in Hypertensive Patients

Background : Hypertension is a condition of systolic blood pressure ≥140 mmHg and diastolic blood pressure ≥90 mmHg. Hypertension can be prevented and avoided with a healthy diet. Dietary arrangements in hypertensive patients really need family support so that patients are able to undergo the treatment process properly according to the doctor's recommendations. The purpose of this study is to analyze the relationship between family support and compliance with diabetes in hypertensive patients at the heart specialist polyclinic of Muhammadiyah Gresik Hospital. Method : The design of this study is a correlation with a population of 93 hypertension patients and the sample set is all 93 patients. The sampling technique uses total sampling. The study used questionnaires for diit compliance. This study uses the Chi Square Test. Results: Most of the hypertension patients who were treated at the cardiac specialist polyclinic of Muhammadiyah Gresik Hospital had good family social support as many as 71 patients (76.3%), sufficient family social support as many as 18 patients (19.3%) and insufficient family social support as many as 4 patients (4.4%), The results of the Chi Square test analysis of the research obtained a value of p=0.00 < 0.05, meaning that there was a relationship between social support and diit compliance in hypertension patients. Conclusion: There is a relationship between family social support and compliance with diabetes in hypertensive patients at the heart specialist polyclinic of Muhammadiyah Gresik Hospital. Keywords : Family Social Support, Diit Compliance, Hypertension,

Charge transfer behavior of triboelectric polymers and triboelectric sensors operated under ultrahigh pressure

AbstractThe energy generation performance of triboelectric materials under ultrahigh pressure remains to be investigated. Here, the variations in molecular structure and built‐in electric field of triboelectric polymers under ultrahigh pressure have been thoroughly studied. The attenuation of built‐in electric field and the escaping of triboelectric charges under ultrahigh pressure are observed in different triboelectric polymers, whereas the existence of deep traps allows the built‐in electric field to be recoverable with the release of pressure. Moreover, the macromolecular conformational changes, including twisting molecular chains and crystal structure changes, can also induce the redistribution of deep traps, leading to a sudden increase in built‐in electric field under specific pressure. Finally, a triboelectric sensor for ultrahigh pressure condition is fabricated with excellent cycle repeatability and a total thickness of 2 mm, which has a sensitivity of 0.07 V MPa−1 within a linear region of 1–100 MPa. This study offers in‐depth insight into the physical understanding of charge behavior both on interface and in bulk of triboelectric materials, whereas the proposed ultrahigh pressure sensors can promote various potential applications of triboelectric sensor in extreme environments.

Mn-Na2WO4/SiO2-tridymite with improved stability and selectivity for high-pressure oxidative coupling of methane

Elevated pressures are essential for industrial chemical processes. Oxidative coupling of methane (OCM) is also preferred to be operated at high pressures. This study investigates high-pressure OCM with operando temperature visualization over the Mn-Na2WO4/SiO2 and Mn-K2WO4/SiO2 catalysts (initially with cristobalite SiO2), which have potential applicability in the selective conversion of CH4 to olefins and paraffins frequently measured at ambient pressure. At high pressure condition of 0.9 MPa, we observed the decrease in C2-4 selectivity and stability with time. During the deactivation, the hotspot generated in the catalyst bed was found to shift towards the end of the bed and sintered the catalyst in the process. High-pressure OCM condition was necessary to cause a phase transformation from SiO2-cristobalite to SiO2-tridymite, resulting from high temperatures in the presence of high H2O pressure (>100 kPa) and was found to play a major part in loss of surface area of active site (Na and K). The hotspot’s influence was reduced by increasing the CH4/O2 ratio, and treatment to form SiO2-tridymite prior to the start of the reaction was found to significantly increase the high-pressure stability. After optimizing the reaction conditions and catalyst, the C2-4 selectivity decreased only from 77.0 % to 76.5 % with a CH4 conversion of 12.7 % over 100 h at a total pressure of 901 kPa and a furnace temperature of 775 °C with Mn(2 wt%)-Na2WO4(5 wt%)/SiO2-tridymite catalyst. In addition, a practical method is proposed to design SiO2-tridymite supported alkali metal catalyst. The insights obtained could be used to design new catalysts and minimize stability issues during high-pressure OCM reactions and in other catalyst systems.

The effects of pressure on anticipatory postural adjustments during a jump shot in basketball

BackgroundAnticipatory postural adjustments (APAs) play an important role in feedforward control of dynamic movements, such as jump shot performance in basketball. It is known that jump shot performance declines under pressure from a defender (shot blocker). Research questionDoes pressure from a shot blocker affect the APAs of a jump shot in basketball? Is jump shot performance in basketball associated with APAs? MethodsFourteen healthy male university basketball players performed jump shots under pressure and non-pressure (free) conditions by a shot blocker. Using a force plate, the APAs were defined as occurring until the point of thrust (TH) phase, and ground reaction force (GRF) and center of pressure (COP) at that moment were assessed. To assess jump shot performance, the maximum GRF during the TH phase (THmax), jumping height, and success score of the shot (accuracy score: AS) were measured by using the vertical component of the force plate. Two-way ANOVA examined the effects of the phase and condition on APA duration. The effects of pressure from a shot blocker on each variable (subjective pressure intensity, AS, GRF, and COP) were analyzed using a pairwise t-test or Wilcoxon signed-rank tests. Relationships between changes in jump shot performance and GRF or COP variables were assessed via Spearman’s correlation analysis. Differences between the pressure and free conditions were denoted by p/f (pressure/free). ResultsThe APA duration was shorter under the pressure condition compared to the free condition. The THmax and jump height values were greater under the pressure condition relative to the free condition. Across conditions, changes in COP sway velocity of the APA phase were significantly and negatively correlated with AS. SignificanceThe results of this study suggest that pressure from a shot blocker shortens APA duration and decreases jump shot performance.

Quantum physisorption behavior of methane in nanoporous shales: Model and new mechanism

Methane adsorption in nanoporous shales plays a significant role in the storage and flow of shale gas. Although previously numerous theoretical models have been proposed to describe the gas adsorption behavior, how the potential energy distribution in nanopores impacts gas adsorption remains unclear. The mechanism of methane adsorption in extremely complicated nanopores is still no satisfactory explanation. In this study, a total of 28 shale samples located in the Paleozoic-Mesozoic strata from different sedimentary environments were utilized to investigate the nature and process of quantum physisorption of methane in nanoporous shales. It was suggested that methane confined within nanoscale space shows a quantum effect, and the physisorption behavior of methane may be the result of molecular energy level transition. Further, the quantum physisorption model was developed by considering the quantum potential energy distribution, maximum adsorption amount, gas temperature and gas pressure, which matches the isothermal adsorption data well for a various of shales under widely varied temperature and gas pressure condition. The adsorption amounts of methane with different energy levels can also be obtained by the model. Finally, a new mechanism of the methane quantum physisorption in nanoporous shales was proposed. Uneven spatial distribution of gas molecules and elementary space of gas adsorption are the intrinsic factors of controlling the quantum physisorption behavior. The former is mainly influenced by minimum potential unit (E0) and gas temperature, while the latter is represented by the parameter of maximum adsorption amount (nL) which impacted by specific surface area and gas temperature. Gas pressure only affects the molecule concentration with different energy levels, but does not affect the spatial distribution of molecule. E0 and nL vary in shales from different sedimentary environments, due to the difference in organic matter properties (TOC content and kerogen type), which indirectly impacts the methane physisorption behavior. These results are helpful to deeply understand the storage of methane in shales and improve the efficient development of shale gas. In addition, this study is expected to open a new research direction about the quantum physisorption of gas in nanoporous media.

Glacier Surges Controlled by the Close Interplay Between Subglacial Friction and Drainage

AbstractThe flow of glaciers and ice sheets is largely influenced by friction at the ice‐bed interface that can trigger rapid changes in glacier motion ranging from seasonal velocity variations to cyclic surge instabilities or even devastating glacier collapse. This wide range of transient glacier dynamics is currently not captured by models, and its implications for long‐term glacier evolution are uncertain. This highlights the need of developing improved descriptions for processes that occur at the glacier bed. Here, we present a model that describes the evolution of basal friction inspired by a “rate and state” approach, coupled to models of subglacial drainage and glacier flow, and investigate how these couplings affect the dynamics of glaciers. We show that a wide range of sliding behavior results from a feedback loop between subglacial drainage efficiency and friction which depends on the evolution of a frictional state that can be interpreted as the degree of cavitation or till porosity for hard and soft beds, respectively. In our simulations, we find that glaciers are susceptible to surging if they exhibit a transition to velocity weakening friction associated with a poor sensitivity of the drainage capacity to the frictional state. This potential materializes if the local topography and mass balance create the conditions for high water pressure to build up in an area sufficiently large to exceed a critical length. We advocate accounting for feedback loops between friction and drainage as a promising avenue for better understanding dynamical instabilities of glaciers and ice sheets.

The role of physical exercise in modifying cardiovascular parameters in hypertensive patients

Hypertension is among the top risk factors for cardiovascular diseases. Diversified rehabilitation programs are needed to limit the progression of the high blood pressure condition. The welfare of aquatic therapy is acknowledged, but hydrotherapeutic procedures are rarely used in cardiovascular diseases. The study aims to assess the impact of an exhaustive hydro-kinetic thermo therapeutic program compared to other methods of treatment, i.e., cardiovascular rehabilitation program, recommendation for a healthy life, and antihypertensive medication. Four groups of patients (46 years ±0,32) diagnosed with hypertension participated in four different rehabilitation programs to analyze the impact on their effort capacity. Their ability to achieve average effort without the appearance of fatigue symptoms was studied for a period of eight weeks by monitoring six parameters: systolic blood pressure (SBP), diastolic blood pressure (DBP), Borg Scale, Medical Research Council Dyspnoea Scale (MRC-DS), pulse (P) and oxygen saturation (O2). Group A, which benefited only of recommendations for a healthy life, didn’t register any significant p values between the initial and final evaluation; group B, which had medications and recommendations for a healthy life, registered significant p values for 2 parameters (SBP and P have p<0.0001); group C, which took part in a cardiovascular rehabilitation program, obtained significant p values for 5 parameters (SBP, DBP, Borg, MRC-DS and O2 have p<0.0001); Group D, the recipient of hydrotherapeutic program, registered significant p values for all statistically 6 monitored parameters (SBP, DBP, Borg, MRC-DS, P and O2 have p<0.0001). Physical activity in water performed regularly within a controlled therapeutic program with the thermal and electrotherapy components, leading to improved capacity for the effort by decreasing blood pressure values and dyspnea parameters.

Numerical Simulation of Weak Shock Wave Reflection in Water Media

Abstract Shock wave reflection (SWR) is an interesting physical phenomenon that plays an important role in the ocean engineering. The existing research mainly focused on the gas SWR. Compared with the gas SWR, the water SWR has distinctive features. This article uses numerical methods to study the reflection mode and regularity inside a gas-filled and water-filled wedge. Specifically, we use the fifth-order weighted essentially nonoscillatory method in space and the third-order Runge–Kutta (RK) method in time to solve the compressible Euler equations. The ideal gas equation of state and water equation of state are also considered in the simulations. We developed a numerical solver using the Fortran language based on these equations and numerical methods. The reliability and accuracy of the developed program were validated by the existing theoretical solution and experiment data. Results show that the reflections are different in gas and water media. Regular reflection (RR) and Mach reflection are observed in a gas-filled wedge. However, only the RR is observed in a water-filled wedge for the weak water shock. Besides, it is found that the reflected shock (RS) wave in water is straighter than that in gas medium. Under the same pressure condition, the curvature of the RS wave is larger in a gas medium. The difference in SWR mode can be attributed to the difference in compressibility between the gas and water. It is found that there is a significant increase in temperature behind the incidence shock in the gas due to its high compressibility, which causes the change of local wave speed especially near the reflected wave. However, the temperature and wave speed are approximately constant during the SWR process in water. These distinctions can well explain the difference in SWR modes between gas and water.

Dual-tube MEMS-based spectrophone for sub-ppb mid-IR photoacoustic gas detection

Nowadays, the scientific community and industry are increasingly pressed to provide solutions for developing compact and highly-performing trace-gas sensors for several applications of crucial importance, such as environmental monitoring or medical diagnostics. In this context, this work describes a novel configuration, making use of a mid-IR spectrophone combining the compactness of a photo-acoustic setup, a non-conventional micro-electro-mechanical (MEMS) acousto-to-voltage transducer, and the sensitivity enhancement given by a cost-effective and easy-to-build dual-tube resonator configuration. In the optimal condition of sample pressure, the system developed in this work can achieve a minimum detection limit (MDL) equal to 0.34 ppb when averaging up to 10 s. Compared with previous literature of single-pass photoacoustic-based sensors for N2O, this corresponds to a significant improvement both for the achieved normalized noise equivalent absorption coefficient (NNEA) equal to 1.41 × 10−9 cm−1WHz−1/2, and for a Noise-Equivalent-Concentration (NEC) of 1 ppb obtained at 1 s of averaging time.

Experimental study on effect of pressure on ADS-4 liquid entrainment characteristics in T-junction

Liquid entrainment phenomenon can occur in the T-junction formed by the vertical ADS-4 pipeline and the hot pipe section during SBLOCA process in AP1000 reactor. At present, most of the studies on the liquid entrainment phenomenon in T-junction with large branch pipe concentrate on the atmospheric pressure condition, which is difficult to accurately reflect the real state of the accident process. The liquid entrainment experiments were carried out at 0.1–0.4 MPa on ADETEL facility. The results show that there will be obvious reverse flow phenomenon in the branch at 0.1 MPa and the phenomenon disappears gradually with the increase of pressure. Furthermore, the occurrence of intermittent two-phase slug flow in the horizontal tube was observed at lower pressures. As pressure increases, the entrainment process will become more continuous and stable, with a concomitant reduction in intermittency. The steady-state entrainment liquid level and the onset of entrainment liquid level both decrease with increasing pressure, indicating that increasing pressure can facilitate the liquid entrainment amount. The existing correlations cannot accurately estimate the entrainment amount during SBLOCA in nuclear reactor with a deviation of more than +100% between the predictions and experimental data.

Effects of trade and poaching pressure on extinction risk for cacti in the Atacama Desert.

In this era of a global biodiversity crisis, vascular plants are facing unprecedented extinction rates. We conducted an assessment of the extinction risk of 32 species and 7 subspecies of Copiapoa, a genus endemic to Chile's fog-dependent coastal Atacama Desert. We applied the International Union for Conservation of Nature Red List Categories and Criteria enhanced by expert insights and knowledge. Our primary aim was to analyze the impact of trade and poaching on their extinction risk. We employed machine learning models, including multinomial logistic regression (MLR), decision tree (DT), and random forest (RF), to analyze the relationships between conservation status and various factors. These factors encompassed trade and poaching activities, landscape condition, human footprint, monthly cloud frequency, and biological traits such as evolutionary distinctiveness and maximum diameter. Seven taxa had an area of occupancy (AOO) of <10km2, 10 additional taxa had an AOO of <20km2, and 16 taxa had an AOO of ≤100km2. This reassessment exposed a critical level of extinction risk for the genus; 92% of the taxa were classified as threatened, 41% as critically endangered, 41% as endangered, and 10% as vulnerable. MLR, DT, and RF exhibited accuracies of 0.784, 0.730, and 0.598, respectively, and identified trade and poaching pressure and landscape condition as the primary drivers of extinction risk. Our assessment of Copiapoa showed trade, poaching, habitat degradation, and their synergic impacts as the main drivers of the genus' extinction risk. Our results highlight the urgent need for nations to develop and enforce strategies to monitor and control trade and poaching pressure because these factors are crucial for the long-term persistence of desert plants.

Fabrication and performance evaluation of polycarbonate/polyvinyl alcohol–titanium dioxide thin‐film nanocomposite membranes for water treatment

AbstractIn recent years, there has been growing interest in using polymer nanocomposite membranes as a more advanced method for removing pollutants from water and treating wastewater for various purposes. In this study, thin‐film nanocomposite (TFN) membranes of polycarbonate/polyvinyl alcohol–titanium dioxide thin‐film (PC/PVA–TiO2) were fabricated by dip‐coating a PC substrate in a PVA/TiO2 solution. Various methods, including attenuated total reflectance‐Fourier transform infrared (ATR‐FTIR) spectroscopy, field emission scanning electron microscopy (FE‐SEM), atomic force microscopy (AFM), and water contact angle were utilized to assess the structural characteristics of the produced membranes. The PC/PVA thin‐film composite (TFC) and PC/PVA–TiO2 TFN membranes were then examined in a submerged membrane system to evaluate their effectiveness in filtering humic acid (HA) under various vacuum transmembrane pressure (0.3 and 0.6 bar) condition. The FTIR‐ATR results confirmed the formation of the active layer of PVA/TiO2 nanoparticles (NPs). It was observed that adding 1 wt.% of TiO2 NPs to the active layer of PVA/TiO2 significantly enhanced the water contact angle from 77.5° for PC support to 55.3° for PC/PVA–TiO2 (0.1) TFN membranes. Furthermore, the FE‐SEM results confirmed the formation of an active layer of PVA/TiO2 with a thickness of 237.87 nm. The pure water flux increased from 101.64 L/m2h for the PC/PVA TFC membrane to 144.02 L/m2h and 199.09 L/m2h for the PC/PVA–TiO2 (0.05) and PC/PVA–TiO2 (0.1) TFN membranes, respectively. Also, the results revealed that at lower transmembrane pressure, all membranes showed higher value in HA removal as compared to when higher transmembrane pressure was used.

The Analysis of Differential Saturation in Shale Oil Accompanied by an Enhanced Classification of Fluid Distribution within the Pore

Shale oil saturated by high temperature (20 MPa) and high pressure (60 °C) conditions can not only realize the efficient saturation of shale, but also invert the shale oil return and drainage characteristics under the stratum temperature and pressure due to the heterogeneity of shale formations. In this study, the Chang 7 Member shale samples were collected, and the high-temperature and high-pressure containment device was utilized to saturate the shale oil efficiently under 20 MPa and 60 °C, and the differences of liquid hydrocarbon saturation and the degree of liquid hydrocarbon saturation for different types of pores and fractures in the shale were quantitatively characterized with a low-field nuclear magnetic resonance (NMR) technology. The results show that under the condition of formation temperature (60 °C) and pressure (20 MPa), shale oil saturation can be reached after 14 d of saturation in the shale samples. The shale oil saturation process can be roughly divided into three stages according to the various saturation rates: the rapid saturation stage, the slow saturation stage, and the second rapid saturation stage, and the degree of saturation of shale oil is characterized by a V-shape. The shale oil was distributed into four types of pore-fracture systems: adsorption pores, micropores, seepage fractures, and layer fractures. Additionally, the fluid dominantly distributes in the micropores and seepage fractures, the shale oil saturation degree of the micropores features a continuous increase, while that for the seepage fractures presents a V-shape, which finally determines the shale oil saturation characteristics of the shale.

Recension of boron nitride phase diagram based on high-pressure and high-temperature experiments

Abstract Cubic boron nitride and hexagonal boron nitride are the two predominant crystalline structures of boron nitride. They can interconvert under varying pressure and temperature conditions. However, this transformation requires overcoming significant potential barriers in dynamics, which poses great difficulty in determining the c-BN/h-BN phase boundary. This study used high-pressure in situ differential thermal measurements to ascertain the temperature of h-BN/c-BN conversion within the commonly used pressure range (3–6 GPa) for the industrial synthesis of c-BN to constrain the P–T phase boundary of h-BN/c-BN in the pressure–temperature range as much as possible. Based on the analysis of the experimental data, it is determined that the relationship between pressure and temperature conforms to the following equation: P = a + 1 b T . Here, P denotes the pressure (GPa) and T is the temperature (K). The coefficients are a = −3.8±0.8 GPa and b = 229.8±17.1 GPa/K. These findings call into question existing high-pressure and high-temperature phase diagrams of boron nitride, which seem to overstate the phase boundary temperature between c-BN and h-BN. The BN phase diagram obtained from this study can provide critical temperature and pressure condition guidance for the industrial synthesis of c-BN, thus optimizing synthesis efficiency and product performance.