Hydration Water Research Articles

Polymorphism and Ligand Binding Modulate Fast Dynamics of Human Telomeric G-Quadruplexes

Telomeric G-quadruplexes (G4s) are promising targets in the design and development of anticancer drugs. Their actual topology depends on several factors, resulting in structural polymorphism. In this study, we investigate how the fast dynamics of the telomeric sequence AG3(TTAG3)3 (Tel22) depends on the conformation. By using Fourier transform Infrared spectroscopy, we show that, in the hydrated powder state, Tel22 adopts parallel and mixed antiparallel/parallel topologies in the presence of K+ and Na+ ions, respectively. These conformational differences are reflected in the reduced mobility of Tel22 in Na+ environment in the sub-nanosecond timescale, as probed by elastic incoherent neutron scattering. These findings are consistent with the G4 antiparallel conformation being more stable than the parallel one, possibly due to the presence of ordered hydration water networks. In addition, we study the effect of Tel22 complexation with BRACO19 ligand. Despite the quite similar conformation in the complexed and uncomplexed state, the fast dynamics of Tel22-BRACO19 is enhanced compared to that of Tel22 alone, independently of the ions. We ascribe this effect to the preferential binding of water molecules to Tel22 against the ligand. The present results suggest that the effect of polymorphism and complexation on the G4 fast dynamics is mediated by hydration water.

On the identification of hyperhydrated sodium chloride hydrates, stable at icy moon conditions

Sodium chloride is expected to be found on many of the surfaces of icy moons like Europa and Ganymede. However, spectral identification remains elusive as the known NaCl-bearing phases cannot match current observations, which require higher number of water of hydration. Working at relevant conditions for icy worlds, we report the characterization of three "hyperhydrated" sodium chloride (SC) hydrates, and refined two crystal structures [2NaCl·17H2O (SC8.5); NaCl·13H2O (SC13)]. We found that the dissociation of Na+ and Cl- ions within these crystal lattices allows for the high incorporation of water molecules and thus explain their hyperhydration. This finding suggests that a great diversity of hyperhydrated crystalline phases of common salts might be found at similar conditions. Thermodynamic constraints indicate that SC8.5 is stable at room pressure below 235 K, and it could be the most abundant NaCl hydrate on icy moon surfaces like Europa, Titan, Ganymede, Callisto, Enceladus, or Ceres. The finding of these hyperhydrated structures represents a major update to the H2O-NaCl phase diagram. These hyperhydrated structures provide an explanation for the mismatch between the remote observations of the surface of Europa and Ganymede and previously available data on NaCl solids. It also underlines the urgent need for mineralogical exploration and spectral data on hyperhydrates at relevant conditions to help future icy world exploration by space missions.

New insights into restrained stress and deformation mechanisms of concretes blended with calcium sulfoaluminate and MgO expansive additives using multi-scale techniques

The early-age cracking performance of expansive concrete relies heavily on the temperature, restraint and curing conditions. Empirical methods to use expansive additives are not always reliable in diverse engineering conditions. By using a novel approach with the self-developed temperature stress testing machine (TSTM), this study evaluates the early-age cracking sensitivity of concretes blended with Calcium Sulfoaluminate and MgO expansive additives under different engineering conditions. Their performances under wetting–drying cycles are also compared. To interpret the deformation mechanism in a microscopic scale, pore structures are characterized by mercury intrusion porosimetry and nitrogen adsorption/desorption tests. It is found that MgO concrete with proper reaction activity can offer more effective shrinkage-compensation effect than CSA concretes under high temperature or drying condition, due to its less demand for hydration water, delayed expansion and finer pore structure. The findings in this study offer us new insights in modelling and application of expansive concretes on site.

The Energy Potential of Glassy Volcanic Rock for Cellular Glass Production

A thermodynamic model for cellular glass pore-formation has been developed on the basis of natural volcanic silicate and aluminosilicate glasses. The energy expenses for heating the materials, chemical reactions, breaking the structural bonds of water hydrates, evaporation of the released water, and pore formation of the glass mass are determined sequentially. The enthalpy and Gibbs energy of the complex gas-forming agent HNO3 + SiC are calculated.

Tensile and compressive behavior of Na-, K-, Ca-Montmorillonite and temperature effects

Molecular dynamics (MD) method was applied to simulate the nano mechanical behavior of Na-, K-, Ca-montmorillonite (MMT) under uniaxial tension and compression, and to explore the effects of the loading direction and temperature. The relation between nano mechanical properties of Na-, K-, Ca-MMT and the hydration was investigated, a comparison was made considering the bulk modulus, shear modulus, elastic modulus and Poisson’s ratio. There are significant differences for the nano mechanical behavior of montmorillonite in different directions, the in-plane tensile and compressive elastic modulus and strength are greater than those in perpendicular to the crystal plane. The nano mechanical properties of Na-MMT have a negative relation with temperature. The nano mechanical properties were found to decrease with the increasing hydration for the montmorillonite. The stiffness coefficients are also influenced by the hydration and interlayer cations. The tensile strength of Ca-MMT is smallest among three types of montmorillonite. The bulk modulus, shear modulus, and Young’s modulus of polycrystal Na-, K-, Ca-MMT are also decreasing with the hydration water layers, while Poisson’s ratio remains unchanged with the increasing hydration. By observing the nano structure change, the tension failure is caused by a slip plane due to bond breaks and the compression failure caused by the local buckling of the crystal sheet in x- and y- direction, while in z- direction, the failure is due to the separation of the interlayer water molecules in tension and bond breaks to form a shear band in compression.

Nucleation Curves of Carbon Dioxide Hydrate in the Absence of a Solid Wall

Nucleation kinetics of clathrate hydrate is poorly understood because of the difficulties in determining the essential parameter, nucleation rate. Nucleation rate enables quantitative comparisons of the impacts of various additives and solid walls on nucleation. We made a setup that determines the nucleation curves of structure I─forming CO2 hydrate in quiescent quasi-free water droplets supported by a bulk of liquid perfluoromethyldecalin under isobaric conditions. The results were compared to the nucleation rates of CO2 hydrate in quiescent water that was in direct contact with stainless-steel walls. We assessed the convergence of the nucleation curves with the increasing numbers of nucleation data and compared our results to the nucleation rates of methane/propane mixed gas hydrate in quiescent quasi-free water droplets and the nucleation rates of gas hydrates of various guest types in the presence of solid walls reported in the literature. We found that (1) 400 nucleation events were sufficient to construct a reliable nucleation curve; (2) the addition of stainless-steel walls promoted the nucleation kinetics of CO2 hydrate, as it did to methane/propane mixed gas hydrate; (3) the kinetic parameter was significantly lower than the theoretically expected value, whereas the thermodynamic parameter was comparable to both the theoretically expected value and the experimentally determined value reported in the literature; and (4) CO2 hydrate nucleated over a substantially shallower supercooling range and had higher nucleation rates than those of methane/propane mixed gas hydrate, both in the presence and in the absence of a solid wall.

Influence of direct electric curing on the hydration and microstructure of cement paste excluding ohmic heating

A modified apparatus based on isothermal calorimetry was employed to determine the influence of direct electric curing (DEC) on the hydration of cement paste other than ohmic heating effect. In addition, the effects of DEC on the microstructure of cured cement pastes were investigated by TG, XRD, NMR, SEM and MIP. The results show that the heat release of DEC samples at early-age is increased significantly due to the electrical power. However, the hydration and microstructure of DEC samples in the isothermal environment are familiar with the normal curing sample. This indicates that, other than OH effect, the impact of DEC on the hydration process and microstructure of cement is negligible. Moreover, a theoretical model for predicting the electric power evolution related to porosity, free water content, hydration degree and initial electric power per unit mass was established which is matched well with the actual measurement results.

Prediction of hydrophilic and hydrophobic hydration structure of protein by neural network optimized using experimental data

The hydration structures of proteins, which are necessary for their folding, stability, and functions, were visualized using X-ray and neutron crystallography and transmission electron microscopy. However, complete visualization of hydration structures over the entire protein surface remains difficult. To compensate for this incompleteness, we developed a three-dimensional convolutional neural network to predict the probability distribution of hydration water molecules on the hydrophilic and hydrophobic surfaces, and in the cavities of proteins. The neural network was optimized using the distribution patterns of protein atoms around the hydration water molecules identified in the high-resolution X-ray crystal structures. We examined the feasibility of the neural network using water sites in the protein crystal structures that were not included in the datasets. The predicted distribution covered most of the experimentally identified hydration sites, with local maxima appearing in their vicinity. This computational approach will help to highlight the relevance of hydration structures to the biological functions and dynamics of proteins.

The pore of the KcsA channel, including the entire cavity up to the selectivity filter, participates in selectivity, rectification, and ion transport.

Quantum calculations on the pore of the KcsA channel from gate to selectivity filter (SF) show how the motion of the K+ ions requires a coordination through states as a contact ion pair (CIP) just beyond the gate, then a solvent separated ion pair (SSIP) in the cavity, then again a CIP, as the ion approaches the selectivity filter (SF). Also, results on the hydration/resolvation by protein of the ion at the SF suggest a mechanism for rectification that depends on the water hydrogen bonded to the conserved threonines. K+ loses hydration water, switching to protein solvation at the SF; Na+ cannot move forward to the SF because of inability to lose hydration water to protein, so is selected out. Water confined in the cavity loses translational and rotational degrees of freedom, altering the competition between ion and protein for hydrating water. Calculations (seven positions, single ion, four positions, ion pairs) show limited barriers for a cluster with a pair of K+ ions, but large barriers for a single ion; it does not form exactly a similar SSIP at the entrance to the selectivity filter, but a SSIP at the cavity center and at the selectivity filter. Charge transfer as the ion moves through the pore can change the charge on the ion up to 0.03 q. Rectification occurs at the entrance to the SF, where the conserved threonine hydroxyls plus methyls interact with the ion near the first SF position, forming an effective ratchet and pawl that effects rectification, preventing an ion in the lowest SF position from reclaiming water in the cavity. Water–protein competition is a recurring theme as the ion moves through the pore.

Present and Future Drinking Water Security and Its Impacts on Maternities: A Multi-Scale Assessment of Sudan.

Adequate access to drinking water for hydration and hygiene depends on many factors. We developed the Drinking Water Security Index (DWSI) to assess relative multifactorial drinking water security at different spatial and temporal scales. DWSI is a function of four key indicators of drinking water security: water quality, water accessibility, water continuity, and water availability. We built DWSI with a total of 10 variables and applied the new index in Sudan to assess historical and future drinking water security at state, local, and maternity levels. Analyses at the state level found that the Red Sea and River Nile states are most vulnerable, with the lowest DWSI for both historical and future periods. The 1 km2 pixel level analysis shows large differences in water security within the major states. Analyses at the maternity level showed that nearly 18.97 million people are affected by the 10% of maternities with the lowest DWSI, a number projected to increase by 60% by 2030. Current and future DWSI of maternities providing Emergency Obstetric and Newborn Care was assessed to identify those where urgent action is needed to ensure quality health care in water-secure conditions. This work provides useful information for stakeholders in the health and drinking water sectors in Sudan, to improve public health, reduce preventable mortality, and make the population more resilient to projected environmental changes.

Incoherent Neutron Scattering and Terahertz Time-Domain Spectroscopy on Protein and Hydration Water

Incoherent inelastic and quasi-elastic neutron scattering (INS) and terahertz time-domain spectroscopy (THz-TDS) are spectroscopy methods that directly detect molecular dynamics, with an overlap in the measured energy regions of each method. Due to the different characteristics of their probes (i.e., neutron and light), the information obtained and the sample conditions suitable for each method differ. In this review, we introduce the differences in the quantum beam properties of the two methods and their associated advantages and disadvantages in molecular spectroscopy. Neutrons are scattered via interaction with nuclei; one characteristic of neutron scattering is a large incoherent scattering cross-section of a hydrogen atom. INS records the auto-correlation functions of atomic positions. By using the difference in neutron scattering cross-sections of isotopes in multi-component systems, some molecules can be selectively observed. In contrast, THz-TDS observes the cross-correlation function of dipole moments. In water-containing biomolecular samples, the absorption of water molecules is particularly large. While INS requires large-scale experimental facilities, such as accelerators and nuclear reactors, THz-TDS can be performed at the laboratory level. In the analysis of water molecule dynamics, INS is primarily sensitive to translational diffusion motion, while THz-TDS observes rotational motion in the spectrum. The two techniques are complementary in many respects, and a combination of the two is very useful in analyzing the dynamics of biomolecules and hydration water.

Urinary Hydration Biomarkers and Water Sources in Older Adults with Neurocognitive Disorder.

The risk of dehydration in older adults with neurocognitive disorder (NCD) is controversial. The purpose of this study was to assess hydration status, its determinants, and water intake sources in older adults with NCD. A sample of 30 participants (≥60 years) was included. Sociodemographic, clinical data and one 24-h urine sample were collected. Urinary osmolality, sodium, potassium, volume, and creatinine were quantified. Inadequate hydration status corresponded to urine osmolality > 500 mOsm/Kg, or a negative Free Water Reserve (FWR). Two 24-h food recalls were used to assess dietary intake and water sources. The adequacy of total water intake (TWI) was estimated according to EFSA. The contribution of food and beverages to TWI was calculated, and their associations with the urinary osmolality median were tested. Of the total number of participants, 30% were classified as having inadequate hydration status, with no differences between sexes. Regarding TWI, 68.4% of women and 77.8% of men did not reach the reference values. Water (23%), followed by soup (17%), contributed the most to TWI, while vegetables (2%) and alcoholic/other beverages (3%) contributed the least. According to the median urinary osmolality, there was no significant difference in sociodemographic/clinical characteristics. It is critical not to overlook hydration in this vulnerable population.

A mechanistically motivated constitutive model of biopolymer hydrogels with structural evolution

Understanding the deformation behavior of biopolymer hydrogels would aid in the design of artificial hydrogels and nanoparticle-based drug delivery systems, which have been extensively used in the fields of biomedicine. Here, we develop a mechanistically motivated constitutive model to elucidate the structural evolution of biopolymer hydrogels. A free energy function includingconfigurational entropy of biopolymer nanofibers, potential energy of physical crosslinks, and mixing energy of water molecules is formulated. Both the micro/nanostructures and dynamic features of nanofibrous network under stretching are captured investigating the evolution of physical crosslinks and water hydration. In addition, a quantitative relationship correlating the pore size in the nanofibrous network with mechanical stretching is proposed. Different from chemically crosslinked hydrogels, the pore size of physically crosslinked hydrogels could continuously increase under stretching, which is attributed to the straightening and bundling of biopolymer nanofibers. We further find that a low strain rate or a high swelling ratio promotes the structural evolution of biopolymer hydrogels and increases the pore size of the network. The model predictions are in good agreement with the experimental results. This work could shed light on the deformation mechanisms of physically crosslinked biopolymer hydrogels, thus providing guidelines for the design of drug delivery systems translocating within biopolymer hydrogels.

Topical Delivery of Atraric Acid Derived from Stereocaulon japonicum with Enhanced Skin Permeation and Hair Regrowth Activity for Androgenic Alopecia

Atraric acid (AA) is a phenolic compound isolated from Stereocaulon japonicum that has demonstrated anti-androgen properties and was used to design an alternative formulation for the treatment of alopecia. This new topical formulation was designed using a solvent mixture system composed of ethanol as a volatile vehicle, oleic acid as a permeation enhancer, and water for skin hydration. The ideal topical AA formulation (AA-TF#15) exhibited an 8.77-fold higher human skin flux and a 570% increase in dermal drug deposition, compared to 1% (w/w) AA in ethanol. In addition, compared to other formulations, AA-TF#15 (1% [w/w] AA) activated keratinocytes and human dermal papilla cell proliferation at a concentration of 50 µM AA, which is equivalent to 50 µM minoxidil. Moreover, AA-TF#15 treatment produced a significant increase in hair regrowth by 58.0% and 41.9% compared to the 1% (w/w) minoxidil and oral finasteride (1 mg/kg)-treated mice. In addition, AA-TF#15 showed a higher expression level of aldehyde dehydrogenase 1, β-catenin, cyclin D1, and pyruvate kinase M2 proteins in the skin of AA-TF#15-treated mice compared to that of those treated with minoxidil and oral finasteride. These findings suggest AA-TF#15 is an effective formulation for the treatment of scalp androgenic alopecia.

Influence of Headgroups in Ethylene-Tetrafluoroethylene-Based Radiation-Grafted Anion Exchange Membranes for CO2 Electrolysis.

The performance of zero-gap CO2 electrolysis (CO2E) is significantly influenced by the membrane's chemical structure and physical properties due to its effects on the local reaction environment and water/ion transport. Radiation-grafted anion-exchange membranes (RG-AEM) have demonstrated high ionic conductivity and durability, making them a promising alternative for CO2E. These membranes were fabricated using two different thicknesses of ethylene-tetrafluoroethylene polymer substrates (25 and 50 μm) and three different headgroup chemistries: benzyl-trimethylammonium, benzyl-N-methylpyrrolidinium, and benzyl-N-methylpiperidinium (MPIP). Our membrane characterization and testing in zero-gap cells over Ag electrocatalysts under commercially relevant conditions showed correlations between the water uptake, ionic conductivity, hydration, and cationic-head groups with the CO2E efficiency. The thinner 25 μm-based AEM with the MPIP-headgroup (ion-exchange capacities of 2.1 ± 0.1 mmol g-1) provided balanced in situ test characteristics with lower cell potentials, high CO selectivity, reduced liquid product crossover, and enhanced water management while maintaining stable operation compared to the commercial AEMs. The CO2 electrolyzer with an MPIP-AEM operated for over 200 h at 150 mA cm-2 with CO selectivities up to 80% and low cell potentials (around 3.1 V) while also demonstrating high conductivities and chemical stability during performance at elevated temperatures (above 60 °C).

Effect of Water Deuteration on Protein Electron Transfer

Traditional theories of long-range protein electron transfer describe the reaction rate in terms of the tunneling distance and the reaction free energy. They do not recognize two physical effects: (i) local wetting of the active site by hydration water and (ii) protein identity affecting the rate through dynamics and flexibility. We find, by molecular dynamics simulations, a significant, ∼25 times, slowing down of the rate of protein electron transfer upon deuteration. H/D substitution changes the rate constant pre-exponential factor in the regime of electron transfer controlled by medium dynamics. Switching from light to heavy water increases the effective medium relaxation time. The effect is caused by both a global change in the flexibility of the protein backbone and locally stronger hydrogen bonds to charged residues.

The Association between the Level of Advanced Glycation End Products and Objective Skin Quality Parameters

Advanced glycation end products (AGEs) represent an endogenously produced or exogenously derived group of compounds derived from nonenzymatic glycation. Recent experimental studies are suggesting that AGEs could play an important role in the skin's quality and its aging process. Hence, the aim of this study was to clinically evaluate the AGEs and skin quality parameters across different age groups in the general population. The study included 237 participants. Melanin, erythema, hydration, friction and transepidermal water loss (TEWL) were evaluated using noninvasive probes, while AGEs were evaluated using a skin autofluorescence reader. There was a significant positive correlation between AGEs and the amount of melanin (p < 0.001), erythema (p < 0.001) and TEWL (p < 0.001), while there was a significant negative correlation between AGEs and hydration (p < 0.001) and friction (p < 0.001). After dividing the sample into three groups depending on their age, in all three groups, there was a significant positive correlation between AGEs and the melanin count (p < 0.001) and TEWL (p < 0.001), while there was a significant negative correlation between AGEs and skin hydration (p < 0.001). Multiple linear regression analysis showed that the level of AGEs as a dependent variable retained a significant association with age (p < 0.001), melanin (p < 0.001), erythema (p = 0.005) and TEWL (p < 0.001) as positive predictors. Moreover, AGEs retained a significant association with skin hydration (p < 0.001) and friction (p = 0.017) as negative predictors. These outcomes imply that AGEs could be linked with the complex physiology of the skin and its aging process.

Effect of tartaric acid on the early hydration process and water resistance of magnesium oxychloride cement

The main type of cement used worldwide is Portland cement with an annual production of about 4 billion tons and CO2 emissions of about 8% of total global anthropogenic greenhouse gas emissions. One of magnesium binders being investigated to mitigate this negative effect is associated with the use of magnesium oxychloride (MOC) cement. Different from that of Portland cement, the main composition of MOC cement is magnesia rather than calcia. MOC cement has excellent properties, including low carbon, light weight, low thermal conductivity, and high early strength, but it is not extensively applied in practical engineering due to its poor water resistance. This study investigated the effect of tartaric acid (TA) addition on the water resistance of MOC cement, as well as its effect on the setting time, hydration, compressive strength, phase composition, pore structure, and microstructure. The results show that the hydration of MOC cement was a multi-step process. The initial precipitate was 2 Mg(OH)2·MgCl2·2H2O, which was ultimately transformed 5 Mg(OH)2·MgCl2·8H2O. TA can adsorb on the surfaces of MgO particles via a coordination effect, which increased the surface negative charge concentration of MgO. This inhibited the dissolution of MgO and the formation of 2 Mg(OH)2·MgCl2·2H2O, prolonging the setting time of MOC cement. The addition of TA decreased compressive strength and increased the total porosity of MOC cement, however, promoted the formation of amorphous 5 Mg(OH)2·MgCl2·8H2O in matrix, resulting in an improvement in the water resistance, a decrease in dissolved concentration of Cl−, and an increase in the content of gel pores of MOC cement.

Elucidating the Sluggish Water Dynamics at the Ice-Binding Surface of the Hyperactive Tenebrio molitor Antifreeze Protein.

Quasi-ice-like hydration waters on the ice-binding surface (IBS) of an antifreeze protein (AFP) commonly exhibit sluggish dynamics especially at low temperatures. In this work, we have analyzed molecular dynamics (MD) simulation trajectories at two different temperatures for Tenebrio molitor antifreeze protein (TmAFP) to explore whether the unique quasi-ice-like structuring of hydration water has any impact on making their dynamics slower on the IBS of the protein. Our calculation reveals that, as translational dynamics is coupled with the conformational fluctuations, hydration water on the IBS exhibits sluggish translational motion due to reduced flexibility of the IBS compared to that on the non-ice-binding surface (NIBS) of the protein. Interestingly, it is noticed that rotational motion of hydration water is not coupled with the conformational fluctuations of the surfaces. In that case, structural relaxations of the protein-water (PW) and water-water (WW) hydrogen bonds compete with each other to make the rotational dynamics of hydration water around the IBS either faster or slower with respect to those around the NIBS. At low temperature, the slower structural relaxation of water-water hydrogen bonds dominates and imparts sluggish rotational motion of the hydration water on the IBS of the protein. The slower structural relaxation of water-water hydrogen bonds and hence the retarded rotational dynamics, despite the weak short-lived PW hydrogen bonds on the IBS, is clearly a manifestation of the rigid quasi-ice-like structure of the hydration shell on that surface.

Effects of Milk Amazake on Skin Elasticity, Hydration, and Transepidermal Water Loss: An 8-Week Double-Blind, Randomized, Controlled Trial.

Amazakes made from rice and koji mold are rich in nutrients, such as groups of vitamin B, minerals, essential amino acids, and oligosaccharides, and can improve skin moisturization. However, there are few reports on milk amazake, made from milk and koji mold. Therefore, in this double-blind, randomized controlled trial, we investigate the effect of milk amazake on skin function. Healthy women and men (n = 40) were randomly allocated to the milk amazake or placebo group. The test beverage was consumed once daily for 8 weeks. Skin elasticity, hydration, and transepidermal water loss (TEWL) were measured at baseline and at weeks 4 and 8, and all subjects completed the trial. Skin elasticity (R2 and R5) at 8 weeks was significantly increased in the milk amazake group compared with baseline. In addition, changes in R5 in the milk amazake group were significantly higher than those in the placebo group. Conversely, TEWL, an evaluation item of skin moisturizing function at 8 weeks, was significantly decreased in the active group compared with baseline. In conclusion, milk amazake may be useful as a functional food for improving skin function.