High Solute Concentrations Research Articles

Understanding of macro-segregation in direct-chill cast 2024 alloy with intensive melt shearing based on the evolution of microstructure and temperature field

The influence of intensive melt shearing (IMS) on macro-segregation has been systematically investigated. Experimental results show that the negative centerline segregation is effectively suppressed when the IMS is applied. To reveal the mechanism of IMS on macro-segregation, a quantitative study on the evolution of the slurry region, mushy region, solidification interface, morphology, and concentration of microstructure was carried out. It was confirmed that the IMS parameters determine the dominant mechanism affecting centerline segregation by controlling its action region. When IMS is applied above the liquidus, the fine dendritic structure not only has higher solute content, but also effectively limits the penetration depth of the liquid melt. Moreover, the velocity of the shrinkage flow in the horizontal direction decreases due to the flattening of the solidification interface. At this condition, the above factors play a more dominant role in macro-segregation than the increase of the mushy region thickness. When the action region of IMS changes to the slurry region, the solidification interface profile transforms from a “V” shape to a “VVV” shape. In this case, the influence of the magnitude and direction of the shrinkage flow on macro-segregation is balanced by the near-spherical structure (solute-poor), the increase of permeability, and the thickness of the mushy region. A physical model has been proposed to explain the IMS parameters on macro-segregation.

Ab Initio Shape of Supramolecular Complexes of Cucurbit[8]uril in Solution Found from Small-Angle X-ray Scattering Data

Previous studies of the spatial structure of the guest–host complexes of macrocyclic cavitands cucurbiturils with a number of nitroxyl radicals by ESR, NMR, and crystallographic methods showed that, in aqueous solutions containing a number of nitroxyl radicals as guest molecules, ordered aggregates in the form of an equilateral triangle, with three guest–host monocomplexes located in its vertices, may arise. We performed experiments on small-angle X-ray scattering of aqueous solutions of guest–host cucurbit[8]uril complexes with a stable nitroxyl radical (protonated tempoamine) and, based on the experimental results, carried out ab initio modeling of the shape of aggregates of complexes in the natural state in solution. The search for models of the shape of aggregates was performed either using no additional information about their structure or assuming the presence of a threefold axis. ESR is applied as an independent method for studying the aggregation of complexes in solution. It is shown that the shape of the particles constituting complexes at high cavitand and guest concentrations in an aqueous solution is close in its parameters to an equilateral triangle, which is in agreement with the known crystallographic and ESR data.

Indirect squeeze casting of ZM5 baffle with linear segregation and its formation mechanism

Macro-segregation in squeeze casting leads to inhomogeneous compositional distribution and degradation of mechanical properties. The distribution and formation mechanism of segregation in squeeze casting baffle were investigated by combining simulation software and experiments. The results showed that the segregation in the baffle was mainly distributed in the abrupt transition region of wall thickness. The evolution of segregation was simulated by the phase-field method to study the formation mechanism of segregation. During the solidification of the casting, pressure is applied to force the metal fluid to convect and complement the shrinkage, and the high solute content metal fluid meets in the wall thickness transition region. Highly brittle precipitated phases with overly dense distribution of segregation areas are easy to cracking during the load loading process, which leads to simultaneous cracking of the matrix through the extension of cracks into the matrix by means of load transfer. The T6 (410 °C × 20h + 200 °C × 8h) heat treatment process can reduce the segregation by dissolving the agglomerated island eutectic tissues into the matrix and then aging them uniformly with granular precipitation. The tensile strength of the castings after T6 treatment increased from 172 MPa (141 MPa at the segregation position) to 245 MPa, and the elongation was 3.3 %.

Insights into Co3O4 nano-rod/peroxymonosulfate catalytic oxidation system for chemical cleaning ultrafiltration membrane: Performance, mechanisms, and effects on the membrane stability

In this study, Co3O4 nano-rod (Co3O4-NR) with (110) crystal plane predominant exposure is prepared by a hydrothermal method, and peroxymonosulfate (PMS) was activated via them for ultrafiltration membrane (PVDF and PES membrane) cleaning. Co3O4-NR with (110) planes exposed obtained abundant oxygen vacancies (OV) and low oxidation state Co (Co2+) and therefore showed excellent ability for PMS activation. The Co3O4-NR/PMS system did not require long-term immersion in a high-concentration chemical reagent solution compared with conventional ultrafiltration membrane chemical cleaning. The cleaning process, which was conducted for only 15 min in Co3O4-NR (1.6 g/L)/PMS (2 mM) solution, was sufficient to restore almost all the permeate flux and could remove essentially all the irreversible foulants. The excellent membrane cleaning performance of the Co3O4-NR/PMS system was attributed to the generation of 1O2 and O2•−, which degraded the large-molecule, hydrophobic natural organic matter (NOM) into small-molecule, hydrophilic organic matter. Cyclic experiments showed that Co3O4-NR had excellent reusability, which offered significant cost savings. The consecutive chemical cleaning experiments indicated that the Co3O4-NR/PMS maintained the membrane stability better than the traditional chlorine cleaning method. The system effectively averts membrane damage and polymer structure changes caused by long-term exposure to oxidants. In conclusion, the Co3O4-NR/PMS system has significant advantages in membrane cleaning and broad application prospects.

Thermal and mechanical properties of an Al-Mg-Sc-Zr high strength alloy fabricated by selective laser melting

Thermal management is one of the most promising applications of Al parts fabricated by additive manufacturing, primarily due to the drastically expanded design space enabled by the latter. The thermal properties of additively manufactured Al alloys are crucial for this application but remain poorly understood. The present study focuses on a high-strength Al-Mg-Sc-Zr alloy fabricated by Selective Laser Melting (SLM). The microstructure of the alloy is characterized by optical and electron microscopy, hardness and tensile testing are conducted, and the thermal conductivity and thermal dilatation behavior are tested. The fabricated samples exhibit strong age hardenability and yield strengths reaching ∼460 MPa. The thermal conductivity in the as-built condition is found to be rather low mainly because of the high solute concentration in the Al matrix as well as the fine grain size, and is improved by 33% after 10 h aging due to precipitation of particles. Meanwhile, abnormal non-linear thermal dilatation behavior is observed in the samples above 400 °C, probably related to the expansion of pores. Lastly, orientation dependency with respect to the building direction is found in both thermal conductivity and dilatation, which is associated with the grain alignment and melt pool structures. The above results provide critical knowledge to the process design toward co-optimization of mechanical and thermal properties of Al alloys fabricated by SLM.

Enrichment of surface charge contributes to the stability of surface nanobubbles

Surface nanobubbles are spontaneously formed at the interface between hydrophobic surfaces and aqueous solutions, which show extraordinarily longer lifetime than that was predicted by the classical thermodynamics model. In the present work, by using a surface plasmon resonance microscopy (SPRM) to quantitatively measure the dissolution kinetics of individual surface nanobubbles in real time, we explored the effects of ionic strength and pH value on the dissolution rates (lifetime) of nanobubbles. The results revealed that nanobubbles could exist stably for a long time in low-concentration electrolyte solutions or high-concentration non-electrolyte solutions, while they dissolved quickly in high-concentration electrolyte solutions. With the increase of ionic strength, the dissolution rates were accelerated by 2–3 orders of magnitude, and thus the lifespan of these surface nanobubbles was significantly shortened. In addition to ionic strength, it was further found that, with the increase of acidity or alkalinity of the solution, the dissolution rates of the surface nanobubbles were faster than that in neutral solution. These results demonstrated that the interfacial charge enrichment significantly contributed to the extraordinary stability of the surface nanobubbles.

Approximative approach to optimize concrete foaming concentration in two stage foaming

The article presents the results of a study on foam concentration for the production of foam concrete using a two-stage foam introduction method. The research was conducted by evaluating the strength and density of foam concrete samples manufactured using both the proposed and conventional methods. The optimal composition was determined through several iterations, considering adjustments to the overall quantity of foaming agent and the water-cement ratio. The study revealed that the two-stage foam introduction method enhances the strength properties of foam concrete by promoting the formation of a more uniform porous structure within the material. The initial introduction of a low-concentration foam solution in water creates favorable conditions for the subsequent introduction of a high-concentration foam solution, serving as a structural-forming component. The optimal approach for achieving a stable porous structure involves an initial foam introduction of 15% and a subsequent introduction of 85%. Furthermore, the research highlights the nuances of the relationship between foam concentration, strength, and density of foam concrete, offering deeper insights into the structural properties of the material. The effectiveness of the proposed methodology is substantiated by the achieved technological solution, which provides a pragmatic approach to enhancing the efficiency of foam concrete production through precise foam concentration at both the initial and subsequent stages of the manufacturing process.

A deep learning-enabled smartphone platform for rapid and sensitive colorimetric detection of dimethoate pesticide.

A novel deep learning-enabled smartphone platform is developed to assist a colorimetric aptamer biosensor for fast and highly sensitive detection of dimethoate. The colorimetric determination of dimethoate is based on the specific binding of dimethoate and aptamer, which leads to the aggregation of AuNPs in high-concentration NaCl solution, resulting in an obvious color change from red to blue. This color change provides sufficient data for self-learning enabled by a convolutional neural network (CNN) model, which is established to predict dimethoate concentration based on images acquired from a smartphone. To enhance user-friendliness for non-experts, the CNN model is then embedded into a smartphone app, enabling offline detection of dimethoate pesticide in real environments within just 15min using a pre-configured colorimetric probe. The developed platform exhibits superior performance, achieving a regression coefficient of 0.9992 in the concentration range of 0-10μM. Moreover, the app's performance is found to be consistent with the ELISA kit. These remarkable findings demonstrate the potential of combining colorimetric biosensors with smartphone-based deep learning methods for the development of portable and affordable tools for pesticide detection.

Thiourea resole polymers for recovery of noble element

The recovery of noble elements from secondary source, industrial effluent, which are classified as high concentrated noble elements solution are very essential. Liquid-solid extraction systems are an attractive process used for the separation and purification of noble elements. For this purpose, a solid-phase extraction system was investigated for the recovery of noble metals (Au(III), Pd(II), and Rh(III)). Chelating resins were synthesized by a polycondensation reaction between phenolic thiourea monomers and formaldehyde under alkaline conditions. The resulting polymers were characterized and evaluated for their chelating properties with regard to noble metal sorption. Also, the selectivity of sorption of noble elements was studied in the presence of competitive elements that can be present in effluent waste, such as Zn, Cu, Ni, Fe, and Al. Here, we present a promising materials based on formo-phenolic thiourea resins as a potential candidate for high-capacity (> 350 mg/g for Au; > 50 mg/g for Pd; > 30 mg/g for Rh) and high-selectivity solid-liquid sorption of noble elements, particularly for Au.

Investigation of optimizing indocyanine green solution for in vivo lymphatic research using near-infrared fluorescence indocyanine green lymphangiography

Despite the tireless efforts of many researchers in lymphatic research, indocyanine green (ICG) solution conditions suitable for lymphatic circulation tests have not been perfectly established yet. We aimed to investigate the optimal in vivo conditions of ICG solution to avoid photobleaching and quenching effects, which may affect the accuracy of lymphatic circulation evaluation. After ICG fluorescence intensity (or ICG intensity) was assessed under different in vitro conditions, the image quality of brachial lymph nodes (LNs) and collecting lymphatic vessels (LVs) in eight rats was investigated. The in vitro results showed that ICG intensity depends on concentration and time in various solvents; however, the brightest intensity was observed at a concentration of 8–30 μg/mL in all solvents. ICG concentration in the albumin (bovine serum albumin; BSA) solution and rat’s plasma showed more than two times higher fluorescence intensity than in distilled water (DW) in the same range. However, saline reduced the intensity by almost half compared to DW. In the in vivo experiment, we obtained relatively high-quality images of the LNs and LVs using ICG in the BSA solution. Even at low concentrations, the result in the BSA solution was comparable to those obtained from high-concentration solutions commonly used in conventional circulation tests. This study provides valuable information about the conditions for optimal ICG intensity in near infrared fluorescence indocyanine green (NIRF-ICG) lymphangiography, which may be useful not only for the diagnosis of lymphatic circulation diseases such as lymphedema but also for preclinical research for the lymphatic system.

Collaborative optimization of regeneration unit and power generation unit in reverse electrodialysis heat engine for low-grade heat recovery

Reverse electrodialysis heat engine (REDHE) emerges great potential to harvest the low-grade heat (LGH) produced during the industrial processes and renewable energy utilizations. In the closed-loop system, the power generation unit converts the salinity gradient power (SGP) to electric energy using the reverse electrodialysis (RED) cells, and the regeneration unit recovers the salinity gradient based on LGH. As two units are in series, the regeneration and power generation units should be collaboratively optimized to achieve a high performance of REDHE. Herein, a framework which can unitedly simulate the both units is built, which enables to divide the total efficiency of REDHE to the respective efficiencies of units. LiBr solution as the working fluid and the effects of initial salt concentration, concentration of the high concentration (HC) solution and temperature in RED cells are considered. Results show that the total efficiencies increase with the concentration of HC solution and the RED temperature due to the production of more chemical energy in the regeneration unit. However, a non-monotonic trend of the total efficiency with the initial concentration is discovered, which increases from 4.91% to 5.42% and then decreases to 4.69% when the initial concentration raises from 20 wt% to 25 wt% and then reaches 30 wt% at RED temperature of 25 ℃. Although enhancing the RED temperature to 50 ℃ leads the total efficiencies increase to 6.25%, 7.13% and 6.38%, respectively, the trend is unchanged. The respective efficiencies of units explain the phenomenon by that a higher salinity can decrease the efficiency of the power generation unit by reducing the ionic selectivity in the RED cells, but enhance the efficiency of the regeneration unit. Therefore, the highest total efficiency reached at initial concentration of 25 wt% is the trade-off between the efficiencies of two units. This study indicates that increasing the concentration of HC solution, the RED temperature, and carefully selecting a compromise initial concentration are helpful to achieve a high energy efficiency in a REDHE.

Molecular Dynamics Calculation of the Coordination Behavior of Yb (III) in Sodium Carbonate Solution

Yb (III) shows complex behavior of coordination dissolution and precipitation in carbonate solutions, but the properties of CO32− coordination and hydration to Yb (III) in the solution have not been explicated. In this work, the dissolution rule of Yb (III) with CO32− concentration has been studied. The radial distribution function and the coordination number of CO32− and H2O to Yb (III) were calculated by molecular dynamics simulation, and the complex ion form of Yb was obtained. The ultraviolet–visible spectrum and the ionic structures of Yb (III) complex ions were geometrically optimized and calculated by using density functional theory. Then, the experimental ultraviolet–visible spectra and density functional theory results were combined to verify the molecular dynamics calculations. The results indicate that Yb (III) undergoes precipitation in low-concentration carbonate solution, but, in high-concentration carbonate solution, Yb (III)’s carbonates will undergo dissolution. The main reason for the dissolution of Yb (III)’s carbonates is the coordination effect of CO32− on Yb (III); the coordination of carbonate on Yb (III) occurs with a CO32− concentration range of 0.4~2.0 mol·L−1. Yb (III) mainly exhibits [Yb·9H2O]3+ hydrated form in the aqueous solution, while, in the carbonate solution, [Yb·9H2O]3+ is converted into [Yb(CO3)2·5H2O]− complex. [Yb(CO3)2·5H2O]− complex is the main ionic form in high-concentration carbonate solutions. The analysis method in this work provides guidance for understanding the coordination and hydration characteristics of oxyacid radicals to rare earth elements.

Response of cucumber (Cucumis sativus L. ‘Kiara’) plants, grown on own root or grafted onto different rootstocks, to high nutrient solution concentrations

Response of cucumber (<i>Cucumis sativus</i> L. ‘Kiara’) plants, grown on own root or grafted onto different rootstocks, to high nutrient solution concentrations

Influence of temperature and solute concentration during osmotic dehydration of apple (Malus domestica) cubes on the stability of probiotics

Currently, there is an upsurge in preference for the consumption of probiotic-rich foods. Besides their nutritive function, these compounds have demonstrated, in some instances, medicinal properties. The purpose of this study was to evaluate how temperature and sucrose concentration influenced the stability of probiotics (specifically Saccharomyces boulardii) during the osmotic dehydration of Granny Smith apple (Malus domestica) cubes. We prepared osmotic solutions with different sucrose concentrations (40, 50, and 60°Brix). We inoculated S. boulardii (250 mg each) into these solutions, followed by immersion of 1 cm-cubed apple cubes. We exposed these cubes to varying temperatures (37°C, 42°C, and 47°C) for a duration of 80 min. Various parameters were calculated, including the percentage of weight loss, percentage of solid gain, number of generations, and the doubling time. Results indicated that the apple cubes with more extreme dehydration were those treated at 50°Brix and 47°C exhibiting a weight loss of 40%. The treatment at 60°Brix and 42°C stood out, showing an increase of 350% of solid gain compared to other groups. Additionally, the highest number of generations of the strain occurred in the group treated at 50°Brix and 37°C, with a value of 9.32 ± 0.11 CFU/g and a doubling time of 7.50 ± 0.09 min. In conclusion, we deduced that under conditions of elevated temperatures and high solute concentrations, the S. boulardii strain might undergo inhibition and fail to develop adequately in the apple cubes subjected to osmotic dehydration.

(Invited) Microelectrode-Based Diagnosis of Charge Propagation and Redox Transitions in Concentrated Polyoxometallate Electrolyte of Potential Utility for Redox Flow Battery

Concentrated solutions of Keggin-type silicotungstic acid, as well as the system’s single crystals (H4SiW12O40*31H2O) and their colloidal suspensions have been tested using the microelectrode methodology to determine mass-transport, electron self-exchange and apparent (effective) diffusion-type coefficients for charge propagation and homogeneous (electron self-exchange) rates of electron transfers. Silicotungstic acid facilitates proton conductivity, and undergoes fast, reversible, multi-electron electron transfers leading to the formation of highly conducting, mixed-valence (tungsten(VI,V) heteropoly blue) compounds. To develop useful electroanalytical diagnostic criteria, electroanalytical approaches utilizing microdisk electrodes have been adapted to characterize redox transitions of the system and to determine kinetic parameters. Combination of micoroelectrode-based experiments performed in two distinct diffusional regimes: radial (long-term experiment; e.g., slow scan rate voltammetry or long-pulse chronoamperometry) and linear (short-term experiment; e.g., fast scan rate voltammetry or short-pulse chronocoulometry) permits absolute determination of such parameters as effective concentration of redox centers (C0 ) and apparent transport (diffusion) coefficient (Dapp ). The knowledge of these parameters, in particular of [Dapp 1/2 C0 ] seems to be of importance to the evaluation of utility of redox electrolytes for charge storage.While current densities which reflect dynamics of electrochemical processes have an influence on the systems’ current densities, the viscosity of the electrolyte and the mass transport dynamics are also affected by the nature of the redox-active material and its concentration. Trying to develop useful electroanalytical diagnostic approaches, we have successfully utilized microelectrode-based probes, as well as the historical concepts of charge propagation in semi-solid or semi-liquid systems developed for mixed-valence polynuclear materials in order to characterize concentrated redox electrolytes. Among important parameters are concentration of redox centers (C0 ) and apparent transport (diffusion) coefficient (Dapp ). The knowledge of these parameters and, in particular of [Dapp 1/2 C0 ], are crucial when it comes to evaluation of the diffusional-type charge propagation dynamics in the concentrated electrolyte which may reflect both physical mass transport and electron self-exchange (electron-hopping) contributions. Both potential-step (chronocoulometry, chronoamperometry) and cyclic voltammetric experiments utilizing microdisk electrodes have been adapted to characterization (identification of redox transitions and determination of kinetic parameters) of model inorganic redox electrolytes, namely highly-concentrated solutions or colloidal suspensions of Keggin-type polyoxometallate, silicotungstic acid.

Janus membrane with enhanced interfacial activation for solar evaporation

Low solar spectrum coverage, high evaporation enthalpy, and undesired salt deposition severely limited the solar-driven interfacial evaporation technology for further sewage purification and seawater desalination. To overcome these problems, we designed an amphiphilic Janus-structured polyaniline (PANI)/ZrC/cellulose acetate (CA) (J-PZCA) membrane. Firstly, the interfacial interaction between PANI and ZrC enhances the photoabsorption and photothermal conversion efficiency. Secondly, low thermal conductivity reduces the heat lost at the interface. Most importantly, ZrC could facilitate interfacial activation, which weakens the intermolecular forces of water by affecting the hydrogen bond. Under 1 solar irradiation (1 sun), the composite membrane exhibits a high evaporation rate of 1.31 kg m−2 h−1 and an excellent efficiency of 79.4%. In addition, the sewage purification and seawater desalination experiments reveal a remarkable purification capability of J-PZCA membrane. Especially for the treatment of high-concentration salt solution, it realizes a long-term stable evaporation performance due to the excellent salt deposition resistance. Therefore, the J-PZCA membrane constructed in this study provides a new perspective for the design of efficient interfacial evaporation devices.

Numerical study on density-driven convection of CO2-H2S mixture in fractured and sequential saline aquifers

Dissolution trapping stands as a critical mechanism for the geological carbon storage (GCS) and can be notably improved through density-driven convection. However, to the best of the author’s knowledge, the discussion on density-driven convection of CO2-H2S mixture has been limited to the exclusion of intersected fractures and lithology sequence effects. Therefore, this study aims to systematically investigate the impact of H2S concentration, fractures, and lithology sequence on convective mixing. Four distinct mechanisms that influence convective mixing of CO2-H2S mixtures in the presence of fractures were identified: 1) accelerated downward solute transportation in fractures, 2) coalescence between plumes around fractures and primary down-swelling plumes, 3) high fracture conductivity inhibiting plume migration across fractures, and 4) upward flow in fractures facilitating the transport of high-concentration solute out of the system. Additionally, the effects of lithology sequence on the shape of CO2 plumes and the curve shape of the total flux at the top boundary were described. The results demonstrated that density-driven convection is enhanced with decreasing H2S concentration and increasing fracture interaction angle and fracture conductivity ratio. The magnitudes of density-driven convection, ranked from high to low, are fining downward, uniform, and fining upward lithology sequences. Furthermore, the H2S concentration affects the flow direction within fractures and alters the relative magnitude of the dimensionless concentration in the noise sequences. The findings of this study on a small scale were proven to be applicable on a large scale.

Comparative Investigation of the Spectroscopic Behavior Based on High-Concentrated Solution in Nitrogen and Air Atmospheres.

In order to accurately obtain photometric information of high concentration SO42- and other substances in the process industry, the spectroscopy behavior of SO42-, S2-, Ni2+ and Cu2+ in air and nitrogen atmosphere was compared based on the UV-visible spectrophotometer with a nitrogen replacing the oxygen. Different from Ni2+ and Cu2+, the accuracy of SO42- and S2- in the ultraviolet region was effectively improved by using a nitrogen atmosphere (P detection results were regressed within the limited standard range, RE < 5%). The nitrogen atmosphere suppressed the additional light attenuation caused by its absorption of ultraviolet rays by isolating oxygen and was also reflected in the decrease in the degree of red shift of the characteristic wavelength for SO42- with increasing concentration. Therefore, the detection results of SO42- showed an effective improvement in sensitivity. Nevertheless, according to the complementary experimental results and theoretical calculations, in addition to oxygen absorption, the low detection accuracy of SO42- high concentration is also attributed to the reduction of the energy required for electronic excitation per unit group caused by the interaction between SO42- groups, resulting in a deviation of the C-A curve from linearity at high concentrations. The influence of this intermolecular force on the detection results is far more important than oxygen absorption. The research can provide reliable theoretical guidance and technical support for the pollution-free direct measurement of high-concentration solutions in the process industry and promote the sustainable development of the process industry.

Versatile Liquid Metal/Alginate Composite Fibers with Enhanced Flame Retardancy and Triboelectric Performance for Smart Wearable Textiles.

Liquid metal (LM) shows the superiority in smart wearable devices due to its biocompatibility and electromagnetic interference (EMI) shielding. However, LM based fibers that can achieve multifunctional integrated applications with biodegradability remain a daunting challenge. Herein, versatile LM based fibers are fabricated first by sonication in alginate solution to obtain LM micro/nano droplets and then wet-spinning into LM/alginate composite fibers. By mixing with high-concentration alginate solution (4-6wt.%), the LM micro/nano droplets stability (colloidal stability for > 30d and chemical stability for > 45d) are not only improved, but also facilitate its spinning into fibers through bimetallic ions (e.g., Ga3+ and Ca2+ ) chelation strategy. These resultant fibers can be woven into smart textiles with excellent flexibility, air permeability, water/salt resistance, and high temperature tolerance (-196-150°C). In addition, inhibition of smoldering result from the LM droplets and bimetallic ions is achieved to enhance flame retardancy. Furthermore, these fibers combine the exceptional properties of LM droplets (e.g., photo-thermal effect and EMI shielding) and alginate fibers (e.g., biocompatibility and biodegradability), applicable in wearable heating devices, wireless communication, and triboelectric nanogenerator, making it a promising candidate for flexible smart textiles.

Impacts of Evaporation‐Induced Groundwater Upwelling on Mixing Dynamics in Shallow Wetlands

AbstractGroundwater mixing dynamics play a crucial role in the biogeochemical cycling of shallow wetlands. In this paper, we conducted groundwater simulations to investigate the combined effects of evaporation and local heterogeneity on mixing dynamics in shallow wetland sediments. The results show that evaporation causes groundwater and solutes to upwell from deep sediments to the surface. As the solute reaches the surface, evaporation enhances the accumulation of the solute near the surface, resulting in a higher solute concentration than in deep sediments. Mapping of flow topology reveals that local heterogeneity generates spatially varied mixing patterns mainly along preferential flow pathways. The upwelling of groundwater induced by surface evaporation through heterogeneous sediments is likely to create distinct mixing hotspots that differ spatially from those generated by lateral preferential flows driven by large‐scale hydraulic gradients, which enhances the overall mixing in the subsurface. These findings have strong implications for biogeochemical processing in wetlands.