Entrapped Water Research Articles

Exploring the Water Oxidation Catalytic Activity of a Mn-Based Magnetic Metal-Organic Framework: The Role of Proton Conductivity and Oxygen Evolution Reaction Overpotential.

The present work evaluates the water oxidation catalytic activity of a Mn-based metal-organic framework (MOF), which we envisioned to reduce the oxygen evolution reaction (OER) overpotential because of its high electrical conductivity, facilitated by solvent-encapsulated structural features. The presence of Mn centers induces interesting magnetic features in the MOF, which exhibits impressive cryogenic magnetic refrigeration with a ΔSM value of 29.94 J kg-1 K-1 for a field change of ΔH = 5T at 2.3 K. To the best of our knowledge, the ΔSM value of the current system ranked the highest position among the published examples. The crystal structure aligns perfectly with the thematic expectations and features as many as ten metal-coordinated water molecules, forming an extensive web of a hydrogen-bonded network while facing toward the porous channel filled with another set of much-anticipated entrapped lattice water molecules. Such structural features are expected to manifest high proton conductivity, and detailed investigation indeed yields the best value for the system at 1.57 × 10-4 S/cm at 95% humidity and 85 °C. In order to evaluate the thematic notion of a one-to-one relationship between OER and improved electrical conductivity, extensive electrocatalytic water splitting (WS) investigations were carried out. The final results show highly encouraging WS ability of the Mn-MOF, showing the electrocatalytic surface area value of the active species as 0.0686 F/g with a turnover frequency value of 0.043 [(mol. O2) (mol. Mn-MOF)-1 s-1]. Another fascinating aspect of the current communication is the excellent synergy observed between the experimental WS outcomes and the corresponding theoretical data calculated using density functional theory (DFT). Consequently, a plausible mechanism of the overall OER and the role of the Mn-MOF as a water oxidation catalyst, along with the importance of water molecules, have also been derived from the theoretical calculations using DFT.

Hydrochemical systematics and isotope (δ18O, δD and 3H) variations of aquifer system of southern Bengal Basin: implications for groundwater pollution.

Hydrogeological, hydrochemical and isotopic traits of the groundwater in the Quaternary aquifer system in an urban-periurban locality within and encircling the Kolkata-Howrah twin city in the south Bengal Basin have been synthesised to explain the present- and paleo-hydrological processes, surface and groundwater interaction and mixing dynamics of contamination of groundwater. Rock-weathering, evaporation, ion-exchange and active mineral dissolution are the key processes commanding the groundwater chemistry. Freshwater flushing from the recharge zones had thinned the entrapped sea water which has generated the present-day brackish water by a non-uniform fusion. The best-fit line of the plots of δD and δ18O of groundwater samples displays a slope lower than that of local meteoric water line (LMWL) and global meteoric water line (GMWL) which hints that isotopic constitution of the groundwater of the present area is primarily formed by evaporation before or in the recharging process. A wide range of δ18O values in groundwater suggests that these waters are not blended enough toremove dissimilarities in isotope configuration of recharge water. This also suggests that many groundwaters are a result of mixing of present-day recharge and an older integrant recharged under previously cooler climatic conditions. The groundwater samples are more depleted of oxygen at the shallower level. The depleted samples cluster around the Tolly's nala (canal) where upper aquitard is missing or < 10-m thick. The tritium values range between 0.70 and 15.02 which indicate the occurrence of 'sub-modern', 'a mix of modern and sub-modern water' and 'modern water'. It indicates mingling of isotope-depleted water from the Hugli River by means of Tolly's canal with relatively less-depleted groundwater of Kolkata's late Pleistocene aquifer. The tritium values and Cl/Br ratio of groundwater samples adjoining Tolly's canal and elsewhere refer the direct infiltration of 'modern wastewater and freshwater' which mixes with the 'sub-modern water' in the aquifer system.

Changes of physicochemical and functional properties of processed cheese made with natural cheddar and mozzarella cheeses during refrigerated storage

The present study aimed to investigate changes of physicochemical and functional properties of the processed cheeses (PCs) made with Cheddar (PC1), Mozzarella (PC2) and both of them at a ratio of 1:1 (PC3) during storage at 4 °C for 4 months. The results showed that the type of natural cheese used affected the composition of PCs with lower fat content in PC2 due to the lower fat content of Mozzarella cheese used. PC2 with lower fat content showed decreased meltability and oil leakage compared with PC1 and PC3. The stretchability of all the samples significantly (P < 0.05) decreased during storage, and PC1 showed lower stretchability. This was confirmed by increased protein hydrolysis of all the samples during the storage with a higher level of proteolysis in PC1, leading to decreased stretchability of PCs. Further low-field nuclear magnetic resonance analysis indicated more entrapped water in cheese due to moisture migration into the cheese matrix that might squeeze the fat globules to aggregate, causing more fat leakage during later stages of storage. This was evidenced by microstructural analysis showing different extents of increase in fat particle sizes and decrease in free serum in all the PC samples over the storage time. Therefore, the present study provides further understanding of the mechanism of quality change of PC during refrigerated storage as affected by proteolytic properties and composition of natural cheese used.

The influence of fluid inclusions, organics, and calcite fabric on trace element distributions in stalagmites

Trace elements and calcite fabrics in stalagmites are increasingly employed as indicators of past environmental conditions. The drivers of trace element concentrations and fabrics reflect a complex interplay of factors during crystal growth, and accurate interpretation of geochemical proxies requires a clear understanding of the incorporation of the proxy signal in the stalagmite. We employ a series of non-destructive techniques to compare the spatial distribution of water, organic components, and trace elements and in relationship with calcite fabrics, and evaluate if these distributions are consistent with recent hypotheses about controlling factors on crystal fabrics, fluid inclusions, and element incorporation. We use for the first time Fourier Transformation Infrared Focal-Plane Array (FTIR-FPA) imaging to show the distribution of molecular water (3,400 cm−1 absorbance) and organic matter (2,983 cm−1) in calcite. To test if entrapped water in speleothem calcite affects the abundance or distribution of trace elements, the element distribution (Na, Mg, Sr, U, Al, Y, and Zn) is mapped by Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). Transmitted Light Microscope imaging constrains crystal fabrics. We find that stalagmite areas with strong Organic Matter fluorescence via Confocal Laser Scanning Microscopy coincide with areas of high Fourier Transformation Infrared absorbance at 2,983 cm−1, suggesting common co-location of multiple organic matter types in the stalagmite. While microscopic fluid inclusions visible in transmitted light are also detected by FTIR 3400 cm−1 absorbance, the FTIR additionally detects submicroscopic fluid inclusions, but not evident in transmitted light microscopy. In most samples, Na concentration is elevated in regions of high fluid inclusion density, suggesting that a significant portion of Na may be hosted in entrapped water rather than in the calcite. Only samples with 100-fold higher Y, feature Na concentrations which appear dominated by coupled Y-Na substitution and little influenced by fluid inclusion hosted Na. Our analysis provides new evidence of the influence of fluid inclusions on trace element content of stalagmites and illustrates the utility of several non-destructive imaging techniques to improve interpretations of proxy signals based on trace elements.

Nasal mucoadhesive in situ gelling liquid crystalline fluid precursor system of polyene antibiotic for potential treatment of localized sinuses aspergillosis post COVID infection

Nasal mucoadhesive in situ gelling liquid crystalline precursor system (IGFPS) of nystatin was developed for localized treatment of nasal aspergillosis post COVID infection. The stimuli-sensitive sol system comprising of Monoolein (60%w/w), Oleic acid (10%w/w), Dimethyl sulfoxide (15%w/w), Poloxamer 407 (9%w/w), and the drug (2.23%w/w) exhibited a faster sol–gel transformation in situ with good swelling ability. The small angle X-ray scattering study identified the coexistence of Im3m cubic phase with hexagonal closed pack P63/mmc structures. The subzero differential scanning calorimetry studies identified entrapped interphasal water and free water in the gels with confirmation of gelation due to micellization. Mucoadhesive properties of the gel indicate these systems to prolong the residence time at the site of absorption. The gels followed Non-Newtonian flow pattern characteristic of pesudoplastic type. The oscillatory rheology revealed that high complex viscosity and lower tanδ value provided superior adhesiveness and mucoadhesion ability to the gel. The gel exhibited a drug release of 86% at the end of 8h and of Higuchi kinetics with anomalous transport. The IGFPS exhibited better in vitro antifungal activity in comparison to drug solution. The system demonstrated permeation enhancing effect undamaged cilia and no serious histological changes. Post intranasal administration the maximum concentration (11.79 ± 2.31 μg/ml) was realized in 20 min and the curve showed a decline similar to intravenous. The storage stability of the IGFPS was found to be within acceptable limits for stability. Thus, a nasal mucoadhesive in situ gelling fluid liquid crystalline precursor formulation may represent a promising novel alternative for the localized and systemic delivery of nystatin.

Artificial Water Channels—Progress Innovations and Prospects

Artificial Water Channels—Progress Innovations and Prospects

Preparation of Breathable Cellulose Based Polymeric Membranes with Enhanced Water Resistance for the Building Industry.

This study focuses on the development of advanced water-resistant bio-based membranes with enhanced vapour permeability for use within building envelopes. Building walls are vulnerable to moisture damage and mold growth due to water penetration, built-in moisture, and interstitial condensation. In this work, breathable composite membranes were prepared using micro-fibrillated cellulose fiber (CF) and polylactic acid (PLA). The chemical composition and physical structure of CF is responsible for its hydrophilic nature, which affects its compatibility with polymers and consequently its performance in the presence of excessive moisture conditions. To enhance the dispersibility of CF in the PLA polymer, the fibers were treated with an organic phosphoric acid ester-based surfactant. The hygroscopic properties of the PLA-CF composites were improved after surfactant treatment and the membranes were resistant to water yet permeable to vapor. Morphological examination of the surface showed better interfacial adhesion and enhanced dispersion of CF in the PLA matrix. Thermal analysis revealed that the surfactant treatment of CF enhanced the glass transition temperature and thermal stability of the composite samples. These bio-based membranes have immense potential as durable, eco-friendly, weather resistant barriers for the building industry as they can adapt to varying humidity conditions, thus allowing entrapped water vapor to pass through and escape the building, eventually prolonging the building life.

Formation of graphene nanostructures using laser induced vaporization of entrapped water

Facile construction of graphene nanostructures are potentially important for fundamental studies and various applications owing to its transparency and mechanical strength. Here we found that focused laser irradiation of a graphene/entrapped water/hydrophobic substrate leads to vaporization of entrapped water and consequent formation of graphene nanostructures. Graphene mechanically exfoliated on a hydrophobicized Si substrate was served as a transformable and impermeable nanocontainer in which water anisotropically and slowly diffuses from the weak edges into the van der Waals (vdW)-coupled interstitial volume between graphene and the substrate. Time-lapsed Raman mappings show that water entrapment promotes progressive lowering of the frequencies of the G and 2D bands of graphene and exhibits slower diffusion owing to vdW decoupling of substrate-induced doping and biaxial strain of graphene with hydrophobic substrate. Moreover, vaporized entrapped water promotes nanostructures by graphene sliding and bulging actions. This methodology represents viable approach to produce nanostructures from two dimensional materials.

Non-Fickian Moisture Absorption in Vegetable Fiber Reinforced Polymer Composites: The Effect of the Mass Diffusivity.

This article aims to study the non-Fickian water absorption process in vegetable fiber-reinforced polymer composite using the Langmuir-type model, evaluating the influence of mass diffusivity on the process. The numerical solutions of the governing equations were obtained using the finite-volume method. Transient results of the local and average moisture content, free and entrapped water molecules concentration considering the constant diffusivity and as a function of the average and local moisture content were presented and analyzed. It was observed that the mass diffusivity effectively influences the water absorption behavior, especially in the initial time of the process, where higher differences in the water migration rates into the material are found. The largest free and entrapped water molecule concentration gradients were found close to the composite surface, especially when considering constant mass diffusivity.

Meat texture, muscle histochemistry and protein composition of Eriocheir sinensis with different size traits

The main aim of the present work was to investigate the effect of the inherent differences in the raw muscle on the textural quality of the cooked meat from different sized Eriocheir sinensis. The content of entrapped water was 73.8–77.7 g/100 g in raw muscle. The density and diameter of muscle thick microfilaments ranged between 137 and 158/μm2 and 20.9–27.0 nm. These results demonstrated that the raw muscle from the tender group had a smaller density of larger diameter thick microfilaments and more entrapped water than other samples, which could explain the high tenderness of the cooked meat (P < 0.05). The potential structural proteins that indicated tenderness include myosin regulatory light chain 2, ancient ubiquitous protein 1, tubulin α-2 chain, and β-catenin, was determined using liquid chromatography-tandem mass spectrometry. The inherent attributes of raw muscle could explain the textural differences of the cooked meat from Eriocheir sinensis.

Effects of l-Lysine on the physiochemical properties and sensory characteristics of salt-reduced reconstructed ham

This paper aimed to investigate the dose-effects of l-Lysine (Lys, 0.2% to 0.8%) on the water holding capacity (WHC), textural properties, water mobility and distribution, microstructures and sensory acceptance of reconstructed ham with 50% reduction of added salt. Results showed that reducing salt from 2.50% to 1.25% caused significant increase in cooking loss and centrifuge loss, and decrease in hardness, springiness and chewiness. 0.8% Lys significantly improved the WHC and textural properties of salt-reduced hams, whereas 0.2% Lys further impaired these attributes. Moreover, 0.8% Lys improved the sensory scores for mouthfeel, appearance, taste and global acceptance. The NMR analysis reveals that water distribution and mobility were affected by salt reduction and Lys addition, and hams with 0.8% Lys contained more entrapped water with decreased mobility. Furthermore, a fine network with more bridge-linkage among myofibrils was formed in hams with 0.8% Lys. Therefore, addition of 0.8% Lys showed great potential in developing salt-reduced reconstructed ham with premium technological and sensory qualities.

Water Absorption in Vegetable Fiber-Reinforced Polymer Composites: A Three-Dimensional Investigation Using the Langmuir-Type Model

This work presents a non-steady state and three-dimensional mathematical modeling to predict moisture transport (based on the Langmuir-Type Model) inside the vegetable fiber-reinforced composite materials. The numerical solutions of the governing equations have been obtain using the finite-volume method. The model was apply for vegetable fiber-reinforced polymer composites. Emphasis to the geometrical dimension effect of the composite in the water absorption process was given. Results of the average moisture content, free and entrapped water molecules concentration kinetics and free and entrapped water molecules concentration distributions inside the material along the process are shown and analyzed. In the distributions of the analyzed properties, it was observed that the geometric dimensions of the composite has influence in the water absorption process.

Moisture Absorption in Polymer Composites Reinforced with Vegetable Fiber: A Three-Dimensional Investigation via Langmuir Model.

This work aims to study numerically the moisture absorption in polymer composite reinforced with vegetable fibers using the Langmuir model which considers the existence of free and entrapped water molecules inside the material. A three-dimensional and transient modeling for describing the water absorption process inside the composite and its numerical solution via finite volume method were presented and discussed. Application has been made for polymer composites reinforced with sisal fiber. Emphasis was given to the effect of the layer thickness of fluid close to the wall of the composite in the progress of water migration. Results of the free and entrapped solute (water) concentration, local moisture content and average moisture content, at different times of process, and inside the composite were presented and analyzed. It was verified that concentration gradients of the molecules (free and entrapped) are higher in the material surface, at any time of the process, and concentration of free solute is greater than the concentration of entrapped solute. It was verified that the water layer thickness surrounding the composite strongly affects the moisture absorption rate.

In-situ modified cellulose nanocrystals as water droplet stabilizer in polystyrene beads targeted for water expanded foam

Synthesis of polystyrene beads containing well-dispersed water microdroplets via surfactant free Pickering emulsion polymerization in water-in-oil emulsion followed by suspension method. The water microdroplets with a diameter of 8–15 µm were stabilized using in situ modified cellulose nanocrystals (CNCs). The morphological investigation revealed that the water droplets were surrounded by a dense layer of the modified CNCs. The thermogravimetric analysis confirmed two types of water inside the beads; free water and bound water with release temperatures of 102 and 118 °C, respectively. The bound water was responsible for higher water preservation ability and therefore long shelf-life of the beads, which over 75% of the initial entrapped water was kept 7 months after synthesis. The beads can be expanded at an optimum temperature of 130 °C due to water vapour pressure developed inside the beads. The best max expansion ratio of around 15 was found for the beads included 5.45 wt% of water. During the expansion process, the CNCs were located in the cell wall to reinforce it from rupturing. Eventually, we report a new type of water expanded polystyrene beads synthesized by the use of CNCs, named CNCWEPS, with good expandability and extended shelf-life.

Expanded polystyrene via stabilized water droplet by in-situ modified starch nanocrystals

Synthesis of polystyrene beads containing well-dispersed water microdroplets viasurfactant free Pickering emulsion polymerization in water-in-oil-in-water system. The water microdroplets with a diameter of 8–15 μm were stabilized using in situ modified starch nanocrystals (SNCs). The morphological investigation revealed that the water droplets were surrounded by a densely layer of the modified SNCs. Since the acid hydrolyzed SNCs were sensitive to pH, the basic feature of polystyrene beads was changed with pH, so that the incorporated water content, encapsulation efficiency and droplet number density were increased with pH, but the volume-weighted mean diameter (d4,3) was decreased with pH. The thermogravimetric analysis confirmed two type of water inside the beads; free water and bound water with release temperatures of 103 and 120 °C, respectively. The bound water was responsible for higher water preservation ability and therefore long shelf-life of the beads, which over 40% of the initial entrapped water was kept 7 months after synthesis. The beads can be expanded at an optimum temperature of 135 °C due to water vapor pressure developed inside the beads. The best max expansion ratio of around 16 was found for the beads included 1.8 wt.% of water. During the expansion process, the SNCs were located in the cell wall to reinforce it from rupturing. Eventually, we report a new type of water expanded polystyrene beads synthesized by the use of SNCs, named SNCWEPS, with good expandability and extended shelf-life.

Vesicle-like structure of lipid-based nanoparticles as drug delivery system revealed by molecular dynamics simulations

Lipid-based drug delivery systems are considered as promising vehicles for hydrophobic drug compounds. Lipid distribution within the droplet can affect drug loading capacity in these carriers. However, it is extremely challenging to determine the nanostructure within these carriers through the implementation of the direct experimental methods due to the ultrafine size. Therefore, coarse grained molecular dynamics (MD) simulation was utilized to model different kinds of lipid-based nanoparticles of the diameter about 12 nm including solid lipid nanoparticles (SLN), nanoemulsion (NE), and nanostructured lipid carriers (NLC), and the organization of the lipids within the carriers was explored. The aforementioned nanoparticles consisted of stearic acid, oleic acid as lipids, and sodium dodecyl sulfate (SDS) as a surfactant in water medium. Furthermore, the impact of solid to liquid mass ratio on the lipid distribution within the lipid matrix was investigated regarding the NLC simulations. In the equilibrium state, we observed the vesicle-like structure for all the investigated systems in which the hydrophilic moieties of the lipids and surfactant organized a semi-bilayer fold into the droplet and the hydrophobic tails accumulated among them. It is worth mentioning although SDS as a harsh surfactant, which is a special case, was expected to be present in the surface of the droplet, it penetrated into the lipids. Additionally, our results showed remarkable entrapped water beads inside the droplet in the form of one or more cavities along the internal layer of the head groups which was surrounded by lipid head groups. It was also reported that in the building structure of the nanoemulsion and SLN, in the central parts of the droplets, lipids were denser than the case of NLCs. Moreover, no crystallization occurred within the lipid-based carriers. Finally, the results indicated that, in the case of NLC simulations, the lipid distribution within the lipid matrix was insensitive to the mass fraction of solid to liquid lipids.

Improving the floatability of coal with varying surface roughness through hypobaric treatment

Surface roughness has a great impact on coal floatability, and usually the effect is found to be negative. In this paper, hypobaric treatment was introduced to improve the floatability of coal with varying surface roughness. The floatability was characterized by induction time, and the micro-bubble nucleation theory was proposed to explain the enhancement mechanism of hypobaric treatment. The results show that the induction time was increased with increasing surface roughness. However, hypobaric treatment was proven to be an effective method in mitigating the adverse effects of surface roughness on floatability. Under natural conditions, neither Wenzel nor Cassie model could be used to describe the wetting regime of coal surface. Instead, a mixed wetting state, where water partially wets the asperities on coal surface and partially sits on entrapped air pockets, was more appropriate. It was difficult to drain the entrapped water at the upper part of the grooves; hence, bubble-coal attachment was prevented, leading to the increased induction time at high surface roughness. After hypobaric treatment, the diffused gas molecules in water preferred to nucleate at the sites of air pockets, leading to the formation of micro-bubbles. These micro-bubbles would act as the bridge between macroscopic bubbles and the coal surface, significantly decreasing induction time and improving the coal contact angle and floatability.

Solid-state entrapment of water clusters by 26-membered pentamide unclosed cryptands – probing the para-substituent effect

Twenty six membered unclosed cryptands end-capped with nitrophenyl (1), phenyl (2), and methoxyphenyl (3) amide substituent (lariat arm) were characterized by single crystal X-ray analysis to reveal the role of para-substituent on the solid-state stabilization of water clusters. Host molecules 1 and 3 crystallize in the same space group (P-1) forming isostructural assemblies with the same entrapped octameric water cluster build from a cyclic tetramer connected with four up-and-down positioned pendulous water molecules. In striking contrast, the host molecule 2 bearing the unsubstituted amido-phenyl group crystallizes in P21/c space group in which two host molecules stabilize acyclic water chain. This distinct crystallization behavior may be rationalized by differences in the electrostatic potential surfaces between hosts 1 and 3 as compared with 2 (para-substituent effect).

Diels-Alder addition to H2O@C60 an electronic and structural study

Exohedral reactivity of endohedral fullerenes has aroused a significant interest because of its potential applications. The present letter examines the effect of an entrapped single water molecule on the reactivity of C60. We study the thermodynamics and kinetics of a Diels-Alder reaction occurring at all non-identical bonds of free C60 and H2O@C60. Our calculations show that encapsulation of water does not have a significant effect on H2O@C60 reactivity compared to C60, as attested by the investigation of the reaction under several orientations of H2O inside C60. Reaction and activation energies indicate that [6,6] bonds are the most reactive sites.

Effect of C/N on Water State during Composting of Kitchen Waste and Vegetable Waste Mixture

The objective of this study was to evaluate the effects of the C/N ratio on the water state changes during the composting of kitchen waste (KW) and vegetable waste (VW) mixtures. The C/N ratios in KW and VW were 50.70 and 27.07, respectively, and the VW was added to the KW to amend the C/N ratio. Five composting treatments were used, R1 with 0% KW, R2 with 25% KW, R3 with 50% KW, R4 with 75% KW, and R5 with 100% KW, and the initial C/N ratios increased in the order R1 &lt; R2 &lt; R3 &lt; R4 &lt; R5. As the composting process progressed, the capillary water (CW) and multi-molecular-layer water (MMLW) were changed into entrapped water (EW), and a high C/N ratio could delay the changes in the water state. The percentage of EW and CW significantly positively correlated with the C/N ratio during the composting of KW. The composting process performed better in treatments R2 and R3 than in the other treatments, and it was found that treatments R2 and R3 each had a lag phase of around 4 d until the water states started to change.