Water Phase Research Articles

Comparison of Hydrogen Bonded Organic Framework with Reduced Graphene Oxide-Pd Based Nanocatalyst: Which One Is More Efficient for Entrapment of Nitrophenol Pollutants?

In this study, a Pd nanoparticles@hydrogen-bonded organic framework (Pd NPs@HOF) thin film was fabricated at the toluene-water interface. The HOF was formed through the interaction of trimesic acid (TMA) and melamine (Mel) in the water phase, while Pd(0) was produced from the reduction of [PdCl2(cod)] in the organic phase. The as-synthesized Pd NPs@HOF thin film was demonstrated to be an effective catalyst for the selective reduction of p-nitrophenol and o-nitrophenol to p-aminophenol and o-aminophenol. The porous network of the Pd NPs@HOF introduced strong active sites between Mel, TMA, and Pd(0). Kinetic studies showed that the Pd NPs@HOF catalyst exhibited an enhanced rate of p-nitrophenol and o-nitrophenol reduction in comparison with Pd@reduced-graphene oxide (r-GO) with rates that were 1.7 times faster for p-nitrophenol and 1.5 times faster for o-nitrophenol or even 10 times faster than some Pd-based catalysts, with a maximum conversion of 97.1% which was attributed to the higher porosity and greater surface-to-volume ratio of the Pd NPs@HOF material. Furthermore, π-π stacking interactions enhance the catalytic activity of the Pd NPs@HOF catalyst by increasing the active sites, stabilizing the NPs and trapping the nitrophenols, facilitating the electron transfer, and providing the synergistic effect. Also, contributions of hydrogen bonding, van der Waals forces, electrostatic interactions, and π-σ noncovalent interactions are reasons for better performance of Pd NPs@HOF than Pd/r-GO catalyst with the reduced functional groups.

Preparation of pH-Responsive Oil-in-Water Microemulsion Using a Full-Bio-Based Surfactant Containing a Dynamic Covalent Bond.

A novel pH-responsive full-bio-based surfactant (Ca-S) containing a dynamic covalent bond is synthesized using renewable cashew phenol, 5-chloro-2-furanaldehyde, and taurine. The structure of Ca-S is characterized by Fourier transform infrared spectroscopy (FTIR) and 1H nuclear magnetic resonance (NMR) analysis. Limonene containing oil-in-water (O/W) microemulsions are prepared on the basis of the Ca-S surfactant and are applied to the remediation of oil-contaminated soil under low-energy conditions at ambient temperature. These results show that Ca-S presents lower cytotoxicity against the A549 cell line. The microemulsions feature low interfacial tension and fast response characteristics, along with an optimal pH responsiveness. The microemulsions that undergo rapid and complete phase separation separate into distinct oil and water phases within 5 s in acidic media (pH < 4). In addition, the microemulsion significantly reduces the oil content to below 4%. The microemulsions hold broad application prospects in soil remediation.

Quantitative Analysis Method of Conversion of Type of Microscopic Remaining Oil Based on CT Technology

The distribution and mutual conversion of remaining oil during the process of oilfield development constitute an important basis for guiding the exploitation of remaining oil potential. Based on the visual core displacement method of CT scanning technology, CT scanning images of the oil–water phase in core models at different displacement stages were obtained, and the remaining oil types were classified. On this basis, image segmentation technology was employed to establish the transformation analysis method of remaining oil types, and the mutual transformation of microscopic remaining oil types at different displacement stages was clarified. The ability of displacement media to utilize various remaining oils was further clarified. The results demonstrate that there are significant differences in the distribution of remaining oil after the injection of different displacement media. The displacement media can not only spread the continuous-phase oil in large pores to varying degrees but also transform the discontinuous oil into continuous-phase oil in some small pore tubes, showing a “converging” transformation law, thereby enhancing the utilization degree of various remaining oils. Additionally, the surfactant’s unique capabilities of “micellar solubilization, emulsification, and oil carrying” have good adaptability to the discontinuous oil phase and can transform the discontinuous-phase remaining oil into continuous-phase remaining oil, namely columnar–film–cluster–recovery.

Water phase distribution and its dependence on internal structure in soaking maize kernels: a study using low-field nuclear magnetic resonance and X-ray micro-computed tomography

IntroductionThe formation of yield and quality in maize involves the accumulation of substances such as starch, proteins, and fats, which interact with water within the kernel. Although temporal dynamics of grain moisture and its functional and environmental determinants have been broadly demonstrated, we still do not have a comprehensive understanding of the distribution of water phase within a kernel.MethodsWe investigated the relationship between tissue structural traits, including embryo volume (EMBV), endosperm volume (ENDV), vitreous endosperm volume (VEV), floury endosperm volume (FEV), and water content in different phases, such as bound water, semi-bound water, and free water, in maize kernels under different cultivars, nitrogen application rates, and soaking durations by combining low-field nuclear magnetic resonance (LF-NMR) and X-ray microcomputed tomography (μ-CT) for kernels.ResultsThe results demonstrate that bound water is the major phase (57-82%) in maize kernels, and this proportion decreases with prolonged soaking duration. The bound water content and semi-bound water content positively correlate to ENDV, VEV, and EMBV, whereas free water content correlates to ENDV, EMBV, and VEV in descending order of correlation coefficient. This indicates that water might penetrate the embryo through the pedicel and vitreous endosperm through the pericarp during soaking.DiscussionFinally, we suggested that the proportion of semi-bound water could be a robust indicator to predict moisture content in maize kernels. The study provides a preliminary understanding of the structural basis of water distribution in maize kernels, thereby opening up the potential for designing efficient production systems and breeding cultivars well-suited for mechanical harvesting.

Ethiodized Oil Pickering Emulsion for Sustained Release of Anti-PD-L1 Antibodies.

This research aimed to develop and assess a Lipiodol Pickering emulsion containing anti-Programmed cell Death Ligand 1 (PD-L1) antibodies through in vitro experiments. The emulsion was created by combining Lipiodol with poly (lactic-co-glycolic acid) (PLGA) nanoparticles and anti-PD-L1 antibodies. Confocal laser microscopy was used to evaluate the encapsulation of the antibodies within the Pickering emulsion. To assess the stability, the emulsion was visually examined, and droplet sizes were measured under a light microscope. For the sustained release evaluation, the emulsion was introduced into saline and incubated in a shaking bath, after which the supernatant was collected over time. The concentration of anti-PD-L1 antibodies in the supernatant was determined using a bicinchoninic acid assay. Western blotting and flow cytometry were employed to confirm the functionality of the released antibodies. A conventional Lipiodol emulsion was used as a control for comparison. The anti-PD-L1 antibodies were encapsulated within the layer of PLGA nanoparticles, positioned at the interface between the water and oil phases, as confirmed by confocal laser microscopy. The Lipiodol Pickering emulsion demonstrated long-term stability with significantly smaller droplet sizes (P < 0.001). Moreover, the emulsion facilitated a gradual and sustained release of the anti-PD-L1 antibodies over an eight-week period (P < 0.001). The antibodies released from the emulsion specifically targeted PD-L1. This study demonstrated that Lipiodol Pickering emulsions effectively encapsulate anti-PD-L1 antibodies and enable their sustained release, highlighting their potential as a therapeutic agent for primary and secondary liver cancers.

Cellulose particles filled oil-in-water emulsion: a facile strategy to prepare edible oleogels

Abstract In this work, a facile strategy of filling the O/W emulsions with cellulose particles to prepare edible oleogels was reported. Two preparation processes, particle filling in water phase of emulsion (PFWP) and one pot dispersing (OPD) are adopted. The effect of cellulose particle concentration and water content on the formation and properties of oleogels were evaluated. Results showed that both of the two processes (PFWP and OPD) could form an oleogels, within a wide range of particle concentration (20 wt% – 40 wt%) and water contents (15 wt% – 25 wt%). The formed oleogels have good centrifugal stability, thixotropic recovery properties and thermostability. The storage moduli of the oleogels increased with an increase of cellulose particle concentration, which is associated with the stronger capillary bridges network. Our results provide a fast and simple approach for oil structuring, which should have great potential application in food industry, especially in food bakery.

Experimental Study on the Behavior of Gas–Water Two-Phase Fluid Flow Through Rock Fractures Under Different Confining Pressures and Shear Displacements

Understanding the flow behaviors of two-phase fluids in rock mass fractures holds significant importance for the exploitation of oil and gas resources. This paper takes rock fractures with different surface roughness characteristics as its research object and conducts experiments on the gas–water seepage laws of fractures under various confining pressures and shear displacements. The results indicate that the higher the fracture surface roughness, the larger the equivalent fracture width and the higher the single-phase permeability of gas/water in the fractures. During gas–water two-phase flow, when the water phase split flow rate is high, the influence of the confining pressure and fracture surface morphology on the water phase is significantly higher than that on the gas phase. The relative permeability at the isosmotic point of the fractures increases with the increase in confining pressure and decreases with the increase in roughness. After the dislocation of shale fractures, the interphase resistance within the fractures reduces. The relative permeability of the water phase increases more significantly compared to that of the gas phase. The water phase split flow rate at the isosmotic point does not change significantly, and the relative permeability at the isosmotic point increases. This research is helpful for guiding the protection based on the conductivity capacity of the rock mass fracture network.

Rich Phase Behaviors of One-Dimensional Interfacial Water via Tuning Interfacial Water-Solid Interaction.

Despite numerous studies of water structures at the two-dimensional water-solid interfaces, much less is known about the phase behaviors of water at the one-dimensional (1D) liquid-solid interface. In this work, the 1D interfacial water phase behavior on the outer surface of carbon nanotube-like (CNT-like) models is studied by tuning the Lennard-Jones potential parameter ε of the surface atoms at various temperatures. Extensive molecular dynamics simulations show that ice nanotubes (INTs) can be spontaneously formed on CNT-like model surfaces without nanoconfinement. INTs with flat-square walls (INTs-FSW) are formed on the CNT-like model surface when the ε value is beyond a critical value εc. The value of εc exponentially increases as temperature rises. Contrary to the prevailing formation of INTs-FSW at a relatively strong water-surface interaction, INTs with bilayer hexagonal walls are formed at a weak interfacial interaction with the ε value being in a modest range. An ε-T phase diagram is constructed for the 1D interfacial water on the CNT(100, 0) model surface. Rich phases of H2O are given in different regions of the phase diagram, depending on the water-surface interaction. This comprehensive study not only provides new insight into the phase behavior of 1D interfacial water but also can guide future experiments to produce INTs without nanoconfinement.

Slow sand filters with variable filtration rates for rainwater purification: Microecological differences between biofilm and water phases.

Slow sand filters (SSFs) have been increasingly applied to rainwater purification in recent years, but the response of SSFs to fluctuating rainfall, as well as the biofilm- and water-phase microecology in SSFs are still poorly understood. This study systematically evaluated the rainwater purification performance of SSFs and compared the bacterial community structure, assembly processes and molecular ecological interactions between the biofilm and water phases. The activated carbon and activated alumina filters exhibited the best performance for NH4+-N (18.82%∼64.00%) and TP (>90%) removal, respectively. As the filtration rate increased from 0.1m/h to 0.3m/h, the rainwater purification efficiencies of the three SSFs deteriorated significantly, with the enrichment of Tolumonas, Desulfovibrio and Sulfurospirillum, and reduction in Klebsiella and Enterobacter. The community diversity of biofilm phase was significantly higher than that of water phase, and filtration rate was identified as a key factor in shaping the bacterial community in both phases. The interactions of filtration rate and water quality displayed the best and significant (p<0.01) explanation for microbiome shift, with the higher values in biofilm phase (34.70%) than in water phase (24.02%). Bacterial community assembly in SSFs was determined by stochastic ecological processes, which played a more important role in water-phase communities, with 86.34% following predictions using a neutral community model. The molecular ecological network of biofilm phase exhibited more complexity, lower modularity and more cooperative relationships than that of water phase. Disadvantaged OTUs occupied core and notable positions in the network, with the highest degree and clustering coefficient. Different keystone species were identified in biofilm- (Runella, Aquabacterium, etc) and water-network (Terrimonas) respectively, despite they processed low relative abundances (<0.1%). These results enhance the understanding of microecology in SSFs, and shed new lights on the improvement and promotion of rainwater biological treatment technology.

A multimedia fugacity model for assessing the environmental fate of typical antibiotics in Lake Taihu with emphasis on the biomechanical characteristics of drug delivery systems

The extensive use of antibiotics in the Taihu Lake Basin has led to a significant threat to human and environmental health. In this context, the QWASI model is developed to simulate the fate of typical antibiotics in Lake Taihu. Through this model, real-time tracking of the dynamic changes in antibiotic content is possible. The study primarily focuses on evaluating the fate and transfer of antibiotics in the water and sediment phases of the lake. The model results indicate that most of the simulated concentrations and mass fluxes are within the same order of magnitude as the measured values, demonstrating a good simulation effect. However, an underestimation of the simulated output value occurs in some cases. The sediment layer serves as the main accumulation site for antibiotics, and the mass balance equation is a crucial tool for simulating the environmental distribution of antibiotics. Sulfamethoxazole (SMX) exhibits a relatively high concentration in water due to its large model input. The sensitivity analysis reveals that for ATM, SMX, and OFX, the five input parameters with the most significant impact are the half-life in water, sediment-water partition coefficient, sediment solids concentration, sediment particle density, and sediment-water diffusion MTC. For OTC, the impact of lake water depth is more prominent than the sediment-water mass transfer rate. The uncertainty analysis effectively showcases the model’s stability, with the water phase concentration showing better stability. In this process, each factor is assigned a correlation coefficient to represent its influence on the original content. The sediment phase antibiotic concentration has a relatively high uncertainty. The source intensity assessment in this study utilizes direct monitoring data of the Taihu Lake water body, ensuring higher accuracy. The major factor contributing to prediction errors is the ambiguity of the sediment phase, which is affected by numerous environmental factors. Importantly, when considering the fate of antibiotics in the lake, the biomechanical characteristics of potential drug delivery systems play a vital role. The movement and dispersion of antibiotics within the water and sediment are influenced by biomechanical forces. In the sediment, the porosity and permeability, which are related to biomechanical properties, can determine the rate at which antibiotics penetrate and accumulate. Understanding these biomechanical aspects of drug delivery systems can help in devising more effective strategies for antibiotic remediation. It can also provide insights into how the physical environment interacts with the chemical behavior of antibiotics, ultimately contributing to a more comprehensive understanding of the environmental fate of antibiotics in Lake Taihu. This is the first study to explore the fate of antibiotics in Lake Taihu and offers valuable recommendations for the restoration of antibiotic-contaminated lakes. It enriches the research perspectives on water management, especially in relation to addressing water pollution caused by antibiotic abuse.

A Validated Method for Identification and Quantification of Anthocyanins in Different Black Rice (Oryza sativa L.) Varieties Using High-Performance Thin-Layer Chromatography (HPTLC).

Black rice (Oryza sativa L.) has gained prominence as a functional food because of its rich content of anthocyanins and polyphenols, offering potential health benefits. However, comprehensive research addressing the diverse anthocyanin compositions in black rice cultivars remains limited. This study aimed to quantify anthocyanin contents, specifically kuromanin, cyanidin-3-glucoside, peonidin-3-O-glucoside, peonidin-3-glucoside chloride, and cyanidin-3-rutinoside chloride, in 150 rice varieties sourced from the North Eastern Region of India using a robust high-performance thin-layer chromatography (HPTLC) method. Rice grains of varying colors-black, orange-reddish, and white-were subjected to methanol extraction under dark conditions through cold maceration for 72 h. The resulting extracts underwent separation on HPTLC silica gel 60 F254 plates utilizing an optimized mobile phase of ethyl acetate, 2-butanol, formic acid, and water (9:6:3:3::v/v/v/v). Anthocyanins were found to be present, and they were most visible in white light compared with UV light at 254 and 366 nm. They were analyzed via densitometry under white light illumination in transmission mode following development. Notably, anthocyanins were absent in grains of white and orange-reddish rice varieties, except for specific lines of Joha (JN 71, JN 83, JN 77, and JN 78) and all black rice variants. Among these, BR 15 exhibited the highest kuromanin content (74.14 ± 0.82 μg/mg), while BR8 showcased the highest peonidin-3-glucoside chloride concentration (27.59 ± 0.83 μg/mg). This comprehensive analysis provides detailed insights into the anthocyanin compositions of 15 significant black rice cultivars, offering crucial data for breeding programs targeting enhanced anthocyanin-rich cultivars and the development of functional foods.

Exploring the distribution and fate of bisphenol A in an aquatic microcosm combined with a multimedia model.

Bisphenol A (BPA), a well-known endocrine-disrupting chemical, has garnered significant attention in environmental science and policy. BPA can enter the aquatic environment through different routes, posing potential risks even at a low concentration. In this study, a four-compartment system [water, sediment, biota (zebrafish), and submerged aquatic vegetation (Vallisneria natans)] of a point source continuous discharge microcosm was established to investigate the distribution and fate of BPA in an aquatic microcosm. The fugacity model generated predicted values were highly consistent with those of the experiments. The distribution of BPA in the model indicates that sediment was the dominant sink. The residence time of reaction and advection was 5.8 and 75.2 d, respectively, which showed that BPA was mainly removed from the aquatic microcosm through the reaction in biota (58 %). Sensitivity analysis revealed that emission data were the most influential parameters for the model output. Transfer processes between the water and biota phases had a closer relationship. This study provides technical support for pollution source management and risk assessment for BPA.

Comprehensive evaluation of antibiotic pollution in a typical tributary of the Yellow River, China: Source-specific partitioning and fate analysis.

The partitioning and migrating of antibiotic residues pose a considerable pollution to the river environment. However, a source-specific approach for quantifying the fate of antibiotics is lacking. To further elucidate the migration behavior of antibiotics from different pollution sources in aquatic environments, we introduced a source-specific partition coefficient (S-Kp) based on Positive Matrix Factorization (PMF) model to improve the multimedia model. This study identified six sources of antibiotic pollution in the water and sediment of the Fenhe River. Farmland drainage contributed 2.6 times more antibiotics to sediment than to surface water, whereas livestock sources contributed 0.3 times less to sediment than to water. High S-Kp values were primarily obtained from livestock, aquaculture, and farmland drainage pollution sources, with an average S-Kp value exceeding 200 L/kg. Sulfaquinoxaline (SQX) in sulfonamides (SAs) from livestock sources exhibited the highest S-Kp value of 34,740.04 L/kg. The predicted environmental concentrations indicated that almost 99 % of the antibiotics from the six sources remained in the water phase, with the highest contribution (99.9 %) of azithromycin (AZM) from livestock, pharmaceutical wastewater, and domestic sewage. This study provides novel insights into the migration of antibiotics from source-specific partitions in multimedia environments of watersheds.

Experimental Studies of Enhancing Solar Collector Efficiency by using a Storage Tank Containing Water Pipes and PCM

Thermal energy storage is a crucial process for retaining heat for future use. This experimental study investigates the integration of a storage tank containing water pipes and phase change materials (PCM) with a solar collector system. By employing paraffin wax (RT-42) as the PCM and leveraging its latent heat storage properties, the enhancement of thermal efficiency and energy storage capabilities in the evacuated tube solar collector is evaluated. Experiments were conducted under varying solar radiation intensity and ambient temperatures in winter and summer conditions. A solar collector and heater were tested for efficiency during winter and summer. The collector was installed at 45.5°S and heated with 120 litres of water. The system's efficiency was enhanced with increased solar radiation and flow rates. The thermal charging of the system took place between 8:00 am and 4:00 pm. The results showed longer hot water supply times at 4 L/m. The effect of adding PCMs and water pipes to solar collector systems was investigated, revealing significant improvements in thermal performance and energy storage. The findings showed an enhancement in temperature stability, with peak temperatures reaching 60°C in winter and 75°C in summer at flow rates of 4, 6, and 8 L/m. Using a storage tank, hot water pipes and PCM, especially paraffin wax, with a latent heat of fusion of 174 kJ/kg improved energy retention and hot water supply. The experiment outcomes showed that the summer hot water supply was twice as high as the winter hot water supply. The study also highlights the importance of improving flow rates to absorb and retain heat efficiently. Overall, the combination of PCM and water pipes enhanced the system efficiency and increased the availability of thermal energy.

Janus Protein Nanoparticles Tailoring Bicontinuous Aerogels for Efficient Heavy Metal Ion Absorption.

Bicontinuous structures are exquisite interpenetrating constructs with an optimal balance between connectivity and surface area. Such unique geometry favors exceptional mechanical properties and efficient inward mass diffusion essential for an absorbent material. Although bicontinuous structures are found across many length scales in nature, synthesizing artificial analogs using biological building blocks remains largely unexplored. In this study, it is shown that manipulation of the surface chemistry of rapeseed cruciferin nanoparticles (≈50nm) leads to the formation of a highly amphiphilic stabilizer, ensuring equal wetting of water and oil phases in a demixed system, thereby enabling the formation of bicontinuous emulsions. By further eliminating both volatile liquid phases (water and toluene) through freeze-drying, bicontinuous emulsions are transformed into bicontinuous aerogels featuring highly interpenetrating networks with uniform domain size. These materials, characterized by high surface area (224 m2g-1) and mechanical robustness, can efficiently absorb various heavy metal ions multiple times displaying excellent absorption capacity (up to 200mgg-1) and efficiency (less than 30min). This study is at the forefront of constructing biomacromolecular bicontinuous structures, potentially expanding their applications in diverse fields such as food, cosmetics, and medicine.

Gellan Gum Enhances the Quality of Egg-Based Yoghurt by Changing the Water Phase Distribution and Improving the Gel Texture.

Egg-based yoghurt (EBY) is a novel yoghurt fermented by lactic acid bacteria with high nutritional and health values, serving as a potential alternative to milk-based yoghurt. However, the hardness, adhesiveness, and water-holding capacity of egg-based yoghurt need to be further improved. In this study, the improvement in EBY quality by gellan gum and its underlying mechanism were investigated. The results showed that gellan gum significantly improved the quality of EBY (p < 0.05). Among the five concentration gradients tested, the EBY supplemented with 0.045% gellan gum exhibited the best quality with the highest sensory score of 83.57. With the increasing amount of gellan gum, hydrogen bonding interactions in the yoghurt significantly increased, while ionic bonding remained unchanged, but hydrophobic interactions and disulphide bonding gradually decreased. Low-field NMR assay results demonstrated that gellan gum significantly raised the amount of strongly bonded water while decreasing the amount of immobile water in the yoghurt. Confocal laser scanning microscopy revealed that EBY with 0.045% gellan gum had a better texture, whereas too much or too little gellan gum led to a coarser structure. In summary, gellan gum altered the water phase state and enhanced the water holding capacity through increased hydrogen bonding interactions, which consequently improved the yoghurt's texture and sensory qualities. This study provides a reference for the development and application of EBY.

Humidity dependence of AE activity in sheared quartz gouges and its implication for the micromechanics of friction

Abstract The micromechanics of friction has been investigated from the viewpoint of the healing of real contacts. In this study, the underlying processes of friction are discussed from the viewpoint of the contact junction deformation and failure by measuring the acoustic emission (AE) activity associated with the frictional sliding. Sliding-rate step tests of synthetic quartz gouges sandwiched between metal forcing blocks are conducted using a low-speed (&lt; 700 μm/s) rotary shear apparatus. Humidity is controlled to be dry (~ 5%RH), room (~ 40%RH), humid (100%RH), or wet (saturated without pore pressure control). The frictional behavior is modeled by the rate- and state-dependent friction (RSF) law with two state variables. Shorter critical slip distances of the state evolution would be about the contact junction size, while longer critical slip distances are close to the average diameter of gouge particles. The AE activities are evaluated by AE rate that is the number of AE events per unit sliding distance and the m-value that characterizes the amplitude distribution. As variations in AE activities and the evolution term ( $${b}_{1}$$ b 1 ) with the shorter critical slip distance highly correlate, AE activity may reflect the state of contact junction. While $${b}_{1}$$ b 1 increases with increasing water vapor from dry to humid, AE rate and the m-value are decreased. This may be caused by an increase in inelasticity of the contact junction deformation. Under wet conditions, $${b}_{1}$$ b 1 is similar to that under the humid condition, AE rate is further decreased but the m-value becomes significantly large. This is probably because the failure process of the contact junction changes to less brittle one, implying the impact of phase of water (vapor or liquid) on the brittleness of the failure processes of contact junction. Graphical Abstract

Microscopic Effect of Mixed Wetting Capillary Characteristics on Spontaneous Imbibition Oil Recovery in Tight Reservoirs

The understanding of the mechanisms that govern water spontaneous imbibition in mixed wetting capillary channels plays a significant role in operating the oil extraction and energy replenishment for the tight oil reservoirs. In this work, the conservative form phase-field model together with the Navier–Stokes equation is employed to investigate the influence of the mixed wetting distribution and the wetting degree on the imbibition oil recovery effects and microscopic flow characteristics. Results indicate that there exist different oil detachment modes of spontaneous imbibition, and these modes are determined by the coupled effect of mixed wetting fraction and contact angle size. For the mixed wetting capillary with strong oil wetting, when fw is low, spontaneous imbibition can only partially detach the oil. Low fw slows down the fluid flow velocity and leads to the small imbibition oil recovery rate. After that, the influence of the surface contact angle size of the mixed wetting capillary is discussed. For the complete detachment mode, the capillary tube presents a form of water phase saturated filling, achieving the optimal imbibition oil recovery effect. For the mixed wetting capillary tube with the combination of weak water wetting and strong oil wetting (i.e., θw = 75° and θo = 165°), local spontaneous imbibition turbulence can only detach very little oil at the inlet of the water wetting area, ultimately achieving a recovery efficiency of less than 10%. This work illuminates the spontaneous imbibition oil recovery mechanisms and flow potentiality for the different mixed wetting capillary channels.

Spontaneous Bubble Growth Inside High-Saturation-Vapor-Pressure and High-Air-Solubility Liquids and Emulsion Droplets.

Spontaneous bubble growths in liquids are usually triggered by rapid changes in pressure or temperature that can lead to liquid gas supersaturation. Here, we report alternative scenarios of the spontaneous growths of bubbles inside a high-saturation-vapor-pressure and high-air-solubility perfluorocarbon liquid (PP1) that were observed under ambient quiescent conditions. First, we investigate spontaneous bubble growth inside the single PP1 phase, which was left to evaporate freely. The bubble growth is explained by the difference in the PP1 vapor pressure inside the bubble and that above the freely evaporating PP1 interface. Next, we study the bubble growth inside the liquid PP1 covered with a layer of a second air-saturated immiscible liquid: low-air-solubility water or higher-air-solubility ethanol. In both cases, the bubble growth rates were accelerated, indicating mass transfer of air from the water or ethanol phases to the PP1 phase. The bubble growth rates significantly increase for bubbles trapped at the PP1-water or PP1-ethanol interfaces due to faster air diffusion through the thin PP1 liquid films separating the bubbles from the upper phases. Finally, we consider the case of bubbles inside millimeter-sized PP1 emulsion droplets in water or ethanol. The bubble growth inside the droplet leads to an increase in the PP1 droplet's effective buoyancy and to the detachment of the droplets from the substrate. The observed bubble growth rate in the case of emulsion droplets was much faster for PP1 droplets in ethanol than for PP1 droplets in water (minutes vs hours). The underlying physical mechanism of the increase of bubble volumes is the spontaneous mass transfer of both air and PP1 vapor to the bubbles produced by a colloidal diffusion pump effect.

Analysis of the NMR Parameters Shielding and Spin-Spin Coupling Constants of Glycine Conformers.

In this study, we worked at the CCSD/aug-cc-pVTZ level to obtain the conformers of glycine in its neutral and zwitterionic forms in the gas and water phases. We then computed the NMR properties (spin-spin coupling constants and nuclear magnetic shieldings) at the SOPPA/aug-cc-pVTZ-J level. We attempt to elucidate the apparent discrepancy arising from two previous works by Valverde et al. [J. Chem. Phys., 2018, 148, 024305] and Caputo and Provasi [Sci, 2021, 3, 41]. Our optimized structures align with previous theoretical predictions, although some geometries were not found. Additionally, our results suggest that in the gas phase the Δ 1J(O,C) = 1J(Ocis,CO) - 1J(Otrans,CO) is positive when the acid group is in the trans conformation and negative in the cis conformation; however, this trend is not well reproduced in water. From magnetic shielding calculations, we cannot distinguish between an O-H in the cis or trans conformation.