Water Diffusion Research Articles

Context Dependency of Hydrophobicity in Intrinsically Disordered Proteins: Insights from a New Dewetting Free Energy-Based Hydrophobicity Scale.

The interaction between amino acids (AAs) and hydration water is fundamental to protein folding and protein-protein interactions. Here, we proposed a hydrophobicity scale for AAs based on their computed free energetic cost of dewetting. This metric captures both entropic and enthalpic contributions of AA-water interactions and allows a systematic and intuitive classification of AAs. Using indirect umbrella sampling (INDUS), we rank individual AAs based on the relative magnitude of their dewetting free energies, from lowest (most hydrophobic) to highest (most hydrophilic). This new hydrophobicity scale is a starting point to evaluate different elements of water hydration behavior, and we focus here on the water structure and translational diffusivity of the hydration waters. While the latter is commonly used as a proxy for hydrophobicity, we show that its behavior is in fact nonmonotonic: hydrophobic residues show slow water diffusion due to highly structured hydration water networks, while highly hydrophilic residues have slow water diffusion due to strong hydrogen bonds with water despite less structured hydration networks. We extend our analysis of hydration properties to intrinsically disordered peptides with varied sequence patterning (sequences of proline/leucine and arginine/glutamic acid residues). We find that the hydration behavior of these peptides is highly context-dependent, with hydrophobic (hydrophilic) patches cooperatively enhancing hydrophobicity (hydrophilicity). These molecular insights of sequence-dependent hydration behaviors may be particularly impactful for the study of intrinsically disordered proteins implicated in liquid-liquid phase separation and aggregation, processes where AAs' hydration environments are complex and changing.

Αn Experimental and Numerical Study on the Drying of Celery (Apium Graveolens L.) Growing in Southern Tunisia

The present work experimentally investigates the curves of the drying kinetics of celery leaves (Apium Graveolens L.) in a drying convective oven. These curves were determined at 50°C, 60°C, and 70°C. For the fitting of the experimental results, the Lewis, Handerson, and Pabis, Page, Midilli &Kucuk, Logarithmic, Modified Page, Wang, and Singh and Two Terms models were used. The Midilli & Kucuk model provided the best fit for the experimental results. The effective water diffusion coefficient (Deff) varied from 3.65×10-10 m2/s to 7.29×10-10 m2/s in the considered temperature range. The higher temperature gave a higher effective water diffusion coefficient and Drying Rate (DR). The activation energy calculated using an exponential expression based on the Arrhenius equation was 31.72 kJ/mol. The Characteristic Drying Curve (CDC) was also determined as a three-degree polynomial.

A Review of Emerging Technologies on the Rehydration Behavior of Foodstuffs

ABSTRACTThis research examines the intricate interplay between novel drying techniques and rehydration processes, emphasizing their influence on food quality and rehydration behavior. Advanced methods such as electromagnetic radiation (microwave and infrared), ultrasound, heat pump drying, low‐pressure superheated steam, high hydrostatic pressure, pulsed electric fields, and ohmic heating were evaluated. Additive manufacturing techniques, including 3D and 4D printing, and nanotechnology's role in enhancing rehydration properties were explored. The study expressed that, methods like freeze‐drying and microwave‐assisted vacuum drying significantly preserved microstructural integrity and porosity, enabling higher rehydration capacities. For example, freeze‐dried samples exhibited up to a 9–10 fold faster rehydration rate, compared to traditional air‐dried methods. Mechanistically, porosity, capillary action, and preserved cellular structures were identified as critical drivers of improved rehydration performance. Emerging techniques such as pulsed electric field and ultrasound enhanced water diffusion and minimized structural damage, further optimizing rehydration efficiency. Insights into parameters like rehydration medium, temperature, and liquid–solid ratio were modeled to predict and enhance product reconstitution quality. The findings underscore the potential of integrating sustainable practices and advanced technologies to revolutionize food processing by reducing energy consumption, minimizing waste, and achieving superior product quality. These innovations position the study as a significant step forward in optimizing rehydration for food industry applications.

Correlations between postmortem quantitative MRI parameters and demyelination, axonal loss and gliosis in multiple sclerosis: A systematic review and meta-analysis.

Magnetic resonance imaging (MRI) is frequently used to monitor disease progression in multiple sclerosis (MS). This study aims to systematically evaluate the correlation between MRI measures and histopathological changes, including demyelination, axonal loss, and gliosis, in the central nervous system of MS patients. We systematically reviewed post-mortem histological studies evaluating myelin density, axonal loss, and gliosis using quantitative imaging in MS. Relevant studies were identified through searches in PubMed, EMBASE, and Web of Science. A total of 38 studies involving 1782 regions of interest from 229 subjects were included. Pooled random-effects models were used to calculate the correlation between demyelination, axonal loss, gliosis, and various MRI parameters, including magnetization transfer ratio (MTR), T1 and T2 relaxation times, myelin water fraction (MWF), proton density (PD), and diffusivities. Pair-wise analyses compared results between lesioned and non-lesioned tissues. Our results demonstrated moderate to strong correlations between MRI parameters and myelin density in MS, with correlation coefficients: T1 (0.72), T2 (0.72), MTR (-0.73), FA (-0.73), RD (0.70), MD (0.70), MWF (-0.82), and PD (0.73). Interestingly, stronger correlations were found in lesioned tissues compared to non-lesioned tissues (P < 0.001). Moderate correlations were found between MRI parameters and axonal loss and gliosis. Our study reveals significant correlations between MRI techniques and histological assessments of myelin, axonal damage, and gliosis in MS. MRI metrics exhibited a more robust association with demyelination in lesioned areas than in non-lesioned brain tissue, highlighting the pronounced degree of myelin degradation in MS lesions. Further investigation is warranted to corroborate these results and refine MRI-based monitoring of MS pathology.

Molecular Dynamics Insights into Water Transport Mechanisms in Polyamide Membranes: Influence of Cross-Linking Degree.

Polyamide (PA) membranes are widely utilized in desalination and water treatment applications, yet the mechanisms underlying water transport within these amorphous polymer materials remain insufficiently understood. To gain more insight into these problems on a microscopic scale, we employ molecular dynamics (MD) simulations to analyze the relationship between the structural properties and the water permeation behavior of PA membranes. Two distinct atomistic models of PA membranes are developed by controlling their degrees of cross-linking (DC). We then conducted a comparative analysis on their microscopic structural properties and configurations of water inside the membranes and investigated how these differences lead to different water diffusion coefficients. Our results reveal that the membrane with a lower DC exhibits higher polymer mobility and a more orderly microscopic structure, allowing the formation of pores that can hold larger water clusters as well as more transient passages between pores, both contributing to an increased water diffusion coefficient. From these observations, we can conclude that water permeability within PA membranes is governed by both the morphology of semirigid pores and the oscillatory movements of the polymer chains. Overall, these findings contribute to a deeper understanding of the intricate mechanisms governing water permeation in PA membranes and may inform the design of more efficient membranes for reverse osmosis and other water treatment technologies.

Molecular Dynamics Simulation of Clay Mineral–Water Interfaces: Temperature-Dependent Structural, Dynamical, and Mechanical Properties

Water interacting with clay minerals—such as kaolinite, montmorillonite, and pyrophyllite—fundamentally governs their geotechnical and environmental functions, thereby influencing parameters such as retention, transport, and stability. Understanding the effects of temperature on water behavior within clay mineral interlayers is critical for predicting the performance of clay–water systems under dynamic environmental conditions. This study performed molecular dynamics simulations to investigate the structural, dynamical, and mechanical properties of interlayer water in three representative clay minerals over a temperature range of 298.15–363.15 K. Our analyses focused on mean squared displacement (MSD), density profiles, hydrogen bond dynamics, and stress distributions, thereby revealing the interaction between water structuring and thermal fluctuations. Results indicated distinct temperature-dependent changes in water diffusion and hydrogen bond stability, with montmorillonite consistently exhibiting enhanced water retention and steadier hydrogen bonding networks across the studied temperature spectrum. Density profiles highlighted pronounced confinement effects at lower temperatures that gradually diminish with increasing thermal energy. Concurrently, the stress distributions revealed the mechanical responses of clay–water interfaces, highlighting the interplay between thermal motion of water molecules and their interactions with the clay surfaces. These findings offer valuable insights into how temperature regulates water behavior in clay mineral interlayers and provide a foundation for advancing predictive modeling and the design of engineered systems in water-rich, thermally variable environments.

Perivascular and parenchymal brain fluid diffusivity in patients with a recent small subcortical infarct.

Fluid exchanges between perivascular spaces (PVS) and interstitium may contribute to the pathophysiology of small vessel disease (SVD). We aimed to analyze water diffusivity measures and their relationship with PVS and other SVD imaging markers. We enrolled 50 consecutive patients with a recent small subcortical infarct. We collected clinical variables, including vascular risk factors and sleep quality scales. All patients underwent a 3-Tesla MRI with standard structural sequences and multishell-diffusion images to obtain extracellular free water content (FW) and water diffusivity along the perivascular space (ALPS) index. We obtained volumetric measurements of white matter hyperintensities (WMH) and PVS, and the number of lacunes and microbleeds. To analyze the association between PVS, ALPS index, FW, and SVD imaging features, we utilized linear regression models including age, sex, history of hypertension and diabetes, Pittsburgh Sleep Quality Index, WMH, and brain volume. All patients (mean age 70 years, 36% women) had usable data. FW and PVS were strongly associated in all models (0.008 < Beta < 0.054; P < 0.045). Higher FW was related to the other SVD features in univariable models and remained significant for WMH (1.175 < Beta < 1.262; P < 0.001) and brain volume (Beta < 0.0001; P < 0.002) in multivariable models. ALPS index was not associated with FW, PVS, or any other SVD markers. The increased extracellular water in SVD suggests that impaired brain fluid exchanges, PVS dilation, and other SVD features are linked. Further investigation is needed to determine the specificity of the ALPS index to PVS diffusion.

Dose-Response Relationship of Phloretin Therapy on Water and Glucose Transport during Experimental Peritoneal Dialysis.

Water retention, ultrafiltration insufficiency, and metabolic complications due to abnormally high glucose concentrations are still common problems in patients treated with peritoneal dialysis. Phloretin, a nonselective inhibitor of facilitative glucose transporter channels (GLUT), has shown to improve water transport and lower glucose absorption in experimental peritoneal dialysis. However, the dose-response relationship remains unknown, and we therefore performed a dose-response study to elucidate the pharmacodynamic properties of intra-peritoneal phloretin therapy. Experimental peritoneal dialysis was performed in fifty healthy Sprague-Dawley rats, using glucose-based dialysis fluid containing five different concentrations of phloretin. We utilized radiolabeled 18F-deoxyglucose (18-FDG) to determine the plasma-to-dialysate transport. The data was then analyzed to determine the dose-response relationship of phloretin according to the Hill-model equation. Intraperitoneal phloretin therapy followed a dose-response relationship where higher concentrations of phloretin lowered the diffusion capacity of 18-FDG and conventional glucose, while enhancing ultrafiltration. Phloretin showed high potency for water removal and diffusion outcomes, requiring low concentrations to achieve substantial effects. Intraperitoneal phloretin therapy followed a distinct dose-response relationship, showing high potency in improving ultrafiltration and reducing glucose absorption in experimental PD. These findings support the therapeutic potential of GLUT-inhibitors like phloretin and support future clinical studies to evaluate efficacy and optimal dosing in patients undergoing PD.

Carbonation under Varying Humidity Conditions: A 3D Micro-Scale Kinetic Monte Carlo Approach.

This paper investigates the impact of varying humidity conditions on the carbonation depth in hardened cement paste using a 3-dimensional microscale kinetic Monte Carlo (kMC) approach. The kMC algorithm effectively simulates the carbonation process by capturing the interplay between CO2 diffusion and relative humidity at the microscale, providing insights into macro trends that align with historical models. The study reveals that the maximum carbonation depth is achieved at relative humidity levels between 55 and 65%, where the balance between water and CO2 diffusion is optimized. At lower relative humidity levels (<55%), a lower carbonation depth is observed. Conversely, at higher relative humidity levels (>65%), increased water content impedes CO2 diffusion, resulting in reduced carbonation depth for cement paste. The kMC model demonstrates a parabolic relationship between relative humidity and carbonation depth. Time series analysis shows that Fick's law is consistently followed, with carbonation depth following the relationship x = k√t at constant relative humidity. The kMC also breaks down the event cycle which shows that after an equilibrium (in terms of rate of events) is achieved between CO2 and H2O at a relative humidity of 75%, a shift occurs in the dominance from reactive to transport processes at a relative humidity of 85%. These findings highlight the importance of humidity in influencing carbonation rates on the one hand and demonstrate the effectiveness of the kMC approach in simulating these complex interactions at the microscale on the other hand.

Associations of ventriculomegaly and white matter hyperintensities with glymphatic dysfunction in idiopathic normal pressure hydrocephalus.

To investigate glymphatic function in idiopathic normal pressure hydrocephalus (iNPH) using the diffusion tensor image analysis along the perivascular space (DTI-ALPS) method and to explore the associations of ALPS index with ventriculomegaly and white matter hyperintensities (WMH). This study included 41 patients with iNPH and 40 age- and sex-matched normal controls (NCs). All participants underwent brain MRI. Based on DTI, we then calculated the ALPS index to obtain the water diffusivity along the perivascular space. Ventricular volume and WMH were also determined. Differences in the diffusivities and ALPS indexes between the iNPH and NC groups were investigated; associations of the DTI-ALPS index with ventriculomegaly and WMH were analysed. Patients with iNPH had a lower ALPS index than NCs (p < 0.001). The ALPS index was significantly correlated with the normalised ventricular volume (r = -0.446, p = 0.004), but not with total WMH volume (r = -0.246, p = 0.126). Further regression analyses indicated that the reduced ALPS index was associated with increased ventricular volume (β = -7.158, p = 0.016), but not with normalised WMH volume (β = -2.796, p = 0.161). The receiver operating characteristic analysis demonstrated the ALPS index's excellent diagnostic performance for iNPH (the optimal cut-off point = 1.322; sensitivity, 100.0%; specificity, 87.5%; AUC = 0.980). Patients with iNPH had a lower ALPS index, which may suggest impaired glymphatic function. This study demonstrated an association of DTI-ALPS index with ventriculomegaly, but not WMH in patients with iNPH. Question Glymphatic dysfunction is crucial in idiopathic normal pressure hydrocephalus (iNPH) development, yet its associations with neuroimaging features remains unclear. Findings Diffusion tensor image analysis along the perivascular space (DTI-ALPS) revealed a reduced ALPS index in idiopathic normal pressure hydrocephalus, negatively correlating with ventricular volume. Clinical relevance DTI-ALPS enables non-invasive assessment of glymphatic function and its relationship with neuroimaging characteristics in idiopathic normal pressure hydrocephalus, facilitating the investigation of glymphatic dysfunction in iNPH pathophysiology.

Effects of temperature and humidity on drying kinetics, final quality and cell wall pectin content of wolfberry (Lycium barbarum)

The effects of four groups of hot-air drying methods, including constant temperature (50 °C) and constant humidity (10%) (CTCH), constant temperature (50 °C) and variable humidity (60%-47%-35%-23%-10%) (CTVH), variable temperature (40 °C-46 °C-52 °C-58 °C-64 °C) and constant humidity (10%) (VTCH), variable temperature (40 °C-46 °C-52 °C-58 °C-64 °C) and variable humidity (60%-47%-35%-23%-10%) (VTVH), on the drying kinetics, product quality and the content of pectin polysaccharides in cell wall of wolfberry were studied. Among them, VTVH showed the highest drying efficiency with the shortest drying time of 13 h, which was 9.52% shorter than that of CTCH, and the highest effective water diffusion coefficient for wolfberries (9.356 × 10−9 m2·min−1). After VTVH drying, samples showed the highest polysaccharides content (46.48%) and rehydration rate (52.24%), as well as the lowest color difference (6.07) and shrinkage rate (66.38%). The content of water-soluble pectin (WSP) in wolfberry was the highest under VTCH drying condition, which was 48.67% higher than that of CTVH drying condition.

Control of water for high-yield and low-cost sustainable electrochemical synthesis of uniform monolayer graphene oxide

With the rapid development of graphene industry, low-cost sustainable synthesis of monolayer graphene oxide (GO) has become more and more important for many applications such as water desalination, thermal management, energy storage and functional composites. Compared to the conventional chemical oxidation methods, water electrolytic oxidation of graphite-intercalation-compound (GIC) shows significant advantages in environmental-friendliness, safety and efficiency, but suffers from non-uniform oxidation, typically ~50 wt.% yield with ~50% monolayers. Here, we show that water-induced deintercalation of GIC is responsible for the non-uniform oxidation of the water electrolytic oxidation method. Using in-situ experiments, the control principles of water diffusion governing electrochemical oxidation and deintercalation of GIC are revealed. Based on these principles, a liquid membrane electrolysis method was developed to precisely control the water diffusion to achieve a dynamic equilibrium between oxidation and deintercalation, enabling industrial sustainable synthesis of uniform monolayer GO with a high yield (~180 wt.%) and a very low cost (~1/7 of Hummers’ methods). Moreover, this method allows precise control on the structure of GO and the synthesis of GO by using pure water. This work provides new insights into the role of water in electrochemical reaction of graphite and paves the way for the industrial applications of GO.

Bio-Oil Impact on Water Diffusion and Durability of Bitumen: Influence of Aging and Salinity

Bio-Oil Impact on Water Diffusion and Durability of Bitumen: Influence of Aging and Salinity

The Effects of Morphology and Hydration on Anion Transport in Self-Assembled Nanoporous Membranes.

Ordered nanoporous polymer membranes offer opportunities for systematically probing the mechanisms of ion transport under confinement and for realizing useful materials for electrochemical devices. Here, we examine the impact of morphology and ion hydration on the transport of hydroxide and bromide anions in nanostructured polymer membranes with 1 nm scale pores. We use aqueous lyotropic self-assembly of an amphiphilic monomer, with a polymerizable surfactant to create direct hexagonal (HI) and gyroid mesophases. UV-induced cross-linking leads to the formation of nanoporous polymers with water continuous channels. The membranes are mechanically robust and chemically durable, resisting degradation during extended exposure to 1 M NaOH solutions. We use a combination of electrochemical impedance spectroscopy, pulsed-field gradient NMR spectroscopy, and molecular simulations to elucidate anion and water transport. The as-prepared hexagonal systems display higher conductivity and lower activation energies for both anions relative to the gyroid system. When compared at equivalent hydration, however, gyroid and hexagonal membranes show similar activation energies, with nearly identical conductivities at ambient temperatures. Both ionic conductivity and water diffusivity increase with increasing hydration. The water uptake as a function of relative humidity for the hexagonal and gyroid mesophases ultimately dictates the water diffusion and magnitude of the ionic conductivity, with the hexagonal system showing overall higher capacity for hydration and thus faster ion transport. The durability of these materials under aggressive alkaline conditions and their relatively high hydroxide ion conductivity suggest that these nanostructured polymers could be of interest as membranes for alkaline fuel cells.

CFD simulation of water diffusion in fruit drying: Case of apricot hemispheres

Food drying is a storage process during which the available water is removed. The present analysis conducted for three drying temperatures 45, 55 and 65 °C and the effective water diffusivity was estimated as 1.69×10-10, 2.91×10-10 and 6.67×10-10 m2/s. Comsol Multiphysics 4.3b was used to model the problem and simulate the process. The apricot hemispheres shrinkage was modelled as function of moisture content reduction. The results showed that water diffusivity, the mass transfer coefficient between the fruit surface and drying air and the activation energy of the process increase with drying temperature. The mass transfer coefficient, km, was estimated as 1.0×10-5, 9.98×10-5 and 0.85×10-2 m/s at 45, 55 and 65 °C. The estimated activation energy was 59.6, 59.9 and 60.8 kJ/mol at 45, 55 and 65 °C. The average relative error between experimental and computational moisture content was 0.47, 0.88 and 1.32% at 45, 55 and 65 °C. The Levenberg-Marquardt (L-M) and Sparse Non-Linear Optimizer (SNOPT) optimization algorithms were implemented.

CFD algorithm for moving boundary problems of isothermal drying and shrinkage: Case of prunes

A moving-boundary FEM model describing isothermal drying of fruit was employed as an inverse problem to estimate water diffusivity and peel resistance, including shrinkage. Water diffusivity and peel resistance were estimated using the Levenberg-Marquardt (L-M) optimisation algorithm based on the experimental drying data. The surface resistance is accounted as the sum of the peel and the diffusive boundary layer resistances, the latter being negligible compared to the former. The estimated peel resistance decreased by 86% as the drying temperature increased from 45 °C to 65 °C and by 44% as the drying temperature increases from 55 °C to 65 °C. The CFD optimisation model efficiently predicted the experimental water content and shrinkage.

Repeated high-dose esketamine in early postnatal rats leads to behavioural deficits with long-term modifications in white matter microstructural integrity

Esketamine is commonly used for sedation or general anaesthesia in infants and young children. However, repeated esketamine administration during periods of rapid brain growth and development may result in various pathophysiological and cognitive changes. Therefore, this study aimed to investigate the influence of recurrent esketamine exposure on long-term behavioural and white matter consequences. Seven-day-old (P7) male rats were allocated to control, high-, and low-dose groups. Behavioural paradigm assessment was conducted at P25–29. Diffusion tensor imaging revealed long-term effects on water diffusivity in the splenium and cingulum white matter of the corpus callosum at P30. Subsequent two-dimensional structure-tensor analysis of brain tissue sections stained with Luxol fast blue (LFB) showed marked changes in the white matter microstructure in rats after multiple exposures to varying esketamine doses. High-dose esketamine significantly reduced activity time and total distance in the open-field experiment. High-dose esketamine exposure might lead to impaired short-term memory in rats. Additionally, the high-dose group showed prolonged immobility time during the forced swimming test. On the balance beam, the high-dose group displayed more right turns and right-foot slips and lower time spent on the rotating bar, indicating motor defects, than did the other groups. Diffusion tensor imaging demonstrated a decreased water molecule diffusion ability in the corpus callosum in the high-dose group. LFB staining indicated microstructural differences in the white matter of animals in the high-dose group. These findings suggest that behavioural deficits in high-dose esketamine-treated rats are at least partially attributed to changes in the white matter microstructure.

Controlled synthesis of ternary acrylamide/sodium acrylate/polyethyleneglycol hybrids by integrating different clays and fillers: a comprehensive evaluation of structural features.

A series of anionic poly(acrylamide-co-sodium acrylate)/poly(ethylene glycol), PAN/PEG, hybrids were conveniently synthesized via free radical aqueous polymerization by integrating bentonite, kaolin, mica, graphene and silica, following a simple and eco-friendly crosslinking methodology. A comparative perspective was presented on how integrated nanofillers affect the physicochemical properties of hybrid gels depending on the differences in their structures. Among the five types of nanofillers, bentonite-integrated hybrid gel had the highest water absorbency, while graphene-integrated gel had the lowest. The elastic moduli of hybrid gels with the same content of inorganic component followed the order graphene > silica > mica > kaolin > bentonite. Adding 1.50% (w/v) bentonite to the PAN/PEG matrix increased the elastic modulus by 1.4 times compared to the as-prepared state, while adding the same amount of graphene created a 4.1-fold increase. By decreasing the synthesis temperature of hybrids to cryoconditions, -18 °C, an increase in the modulus of all gels was observed, while the modulus of graphene-doped gels increased from 25.9 kPa to 39.1 kPa. pH-dependent swelling demonstrated that hybrid gels can dynamically bind or release protons in response to changes in surrounding pH and thus abruptly change their overall dimensions. On-off switching behavior as reversible pulsatile swelling in pH 11.2 and deswelling in pH 2.1 showed that hybrid gels exhibit reversible pH-responsiveness following Fickian diffusion of water into the hybrid matrix. The change in pH of the swelling medium caused a 4.5-fold increase in swelling ratio for the silica-doped hybrid gels. The studies in which anionic hybrids were tested to explore adsorption potential for cationic dye methylene blue (MB) showed that adsorbent properties could be tuned to the desired extent by incorporating different fillers. In terms of efficiency among the selected fillers, the maximum efficiency for MB was obtained as 99.2% and 88.60% for hybrids containing graphene and silica, respectively. The adsorption of MB on hybrids was fit to the three-parameter Sips model rather than the two-parameter models. The results introduced a new perspective on the design of ternary hybrid gels that could effectively address both the mechanical and responsive properties of soft materials, providing a platform for subsequent cationic dye adsorption.

The liquid-vapor water generation characteristics of thermo-responsive polymer based on the multi-scale method.

Thermo-responsive polymer is becoming a potential water purification and water harvesting material. To clarify the water diffusion characteristics, the desorption ratio of liquid water and water vapor for a poly (N-isopropylacrylamide) was researched by the multi-scale method. Firstly, macro and micro structures for the hydrogel with different water content were characterized. Second, the dynamic moisture preserving status of the hydrogel during the desorption process were tested. Thirdly, the dynamic liquid-vapor desorption rate was quantified. The macro volume of the polymer is of liner relationship with water content. During the desorption process, free and immobilized water transfers to immobilized and bound water. About 80% of the purified liquid water can be collected directly in closed environment, while the amount decreased to 21%-25% in air convection condition. The results suggested a heating method for improving liquid water collection rate with low energy cost for practical applications.

Chrysanthemum morifolium Ramat. as a traditional tea material: Unraveling the influence of kill-green process on drying characteristics, phytochemical compounds, and volatile profile

The dried capitulum of chrysanthemums is a traditional material in scented tea, and the kill-green process is a critical step in determining their quality. However, the changes in the physicochemical properties during kill-green and the mechanisms by which these changes affect drying characteristics, metabolic components, and aroma profiles remain unclear. Therefore, this study investigated the changes in water status, polyphenol oxidase and peroxidase activities, and microstructure during high-humidity air impingement kill-green (HHAIK) and steam kill-green (SK), and their effects on drying behavior, color, phytochemicals, and volatile profile of dried chrysanthemums. Results showed that the kill-green process increased the freedom degree of immobile water, reduced the relative content of free water, and induced microstructure alterations, thus enhancing the water diffusion and shortening the subsequent drying time by up to 46.15 %. Compared to SK, HHAIK more rapidly inactivated PPO and POD, causing an improved color profile of dried samples. Dried samples treated with HHAIK for 60 s exhibited higher retention of 9 individual phenolics, total sugar, amino acids, and volatile compounds, thus resulting in higher sensorial acceptance than those treated with SK for 60 s. This study offers theoretical insights and technical support for the future development of high-quality chrysanthemum products.