Water Pore Research Articles

Toward the use of MRI measurements of bound and pore water in fracture risk assessment.

The current clinical assessment of fracture risk lacks information about the inherent quality of a person's bone tissue. Working toward an imaging-based approach to quantify both a bone tissue quality marker (tissue hydration as water bound to the matrix) and a bone microstructure marker (porosity as water in pores), we hypothesized that the concentrations of bound water (Cbw) are lower and concentrations of pore water (Cpw) are higher in patients with osteoporosis (OP) than in age- and sex-matched adults without the disease. Using recent developments in ultrashort echo time (UTE) magnetic resonance imaging (MRI), maps of Cbw and Cpw were acquired from the uninjured distal third radius (Study 1) of 20 patients who experienced a fragility fracture of the distal radius (Fx) and 20 healthy controls (Non-Fx) and from the tibia mid-diaphysis (Study 2) of 30 women with clinical OP (low T-scores) and 15 women without OP (normal T-scores). In Study 1, Cbw was significantly lower (p=0.0018) and Cpw was higher (p=0.0022) in the Fx than in the Non-Fx group. In forward stepwise, logistic regression models using Bayesian Information Criterion for selecting the best set of predictors (from imaging parameters, age, BMI, and DXA scanner type), the area-under-the-receiver operator characteristics-curve (AUC with 95% confidence intervals) was 0.73 (0.56, 0.86) for hip aBMD (best predictors without MRI) and 0.86 (0.70, 0.95) for the combination of Cbw and Cpw (best predictors overall). In Study 2, Cbw was significantly lower (p=0.0005) in women with OP (23.8±4.3 1H mol/L) than in women without OP (29.9±6.4 1H mol/L); Cpw was significantly higher by estimate of 2.9 1H mol/L (p=0.0298) with clinical OP, but only when accounting for the type of UTE-MRI scan with 3D providing higher values than 2D (p<0.0001). Lastly, Cbw, but not Cpw, was sensitive to bone forming osteoporosis medications over 12-months. UTE-MRI-derived measurements of bound and pore water concentrations are potential, aBMD-independent predictors of fracture risk.

Static compression behavior and strength weakening mechanism of dynamically damaged granite after water soaking

In backfill mining, the surrounding rock is dynamically damaged by intermittent mining and blasting. After backfilling, bleed water from the backfill seeps into the surrounding rock, leaving the surrounding rock in a water-rock coupling environment. To study the mechanical properties of surrounding rock in such a scenario, two types of granite specimens were prepared, namely, impact-damaged (ID), impact-damaged and water-soaked (IDWS) specimens. A modified split Hopkinson pressure bar (SHPB) system was first applied to execute the dynamic tests with different impact numbers and confining stresses to prepare the ID specimens. Subsequently, the IDWS specimens were prepared by water soaking tests on half numbers of the ID specimens. Finally, static uniaxial compression tests were performed on ID and IDWS specimens. The test results indicate that the peak strength of ID and IDWS specimens increases with the increase of confining stress, and first increases and then decreases with the increase of number of impacts. The total strength weakening factor of the IDWS specimens is composed of the impact strength weakening factor and the water-induced strength weakening factor, as well as the coupling effect of the two factors. Impact loading increases the number of microcracks and pores inside the IDWS specimens, resulting in a larger contact area between water and microcracks and pores. Compared with ID specimens, water induces more tensile cracks in the IDWS specimens according to the results of electron microscope scanning. This is manifested as the transfer from macro shear failure mode to macro tensile failure, and further reduces the peak strength of the IDWS specimens.

Effect of Water on Effective Pore Structures for Medium-Rank Coal: Based on the Prefreezing Nitrogen Adsorption-Desorption Experiment.

Water is ubiquitous in coal reservoirs, and its distribution can have a remarkable influence on the effective pore space of methane. This study conducted the combination experiments of moisture equilibrium and prefreezing nitrogen adsorption-desorption to explore the adsorption behavior of water in coal pores and thus to reveal the distribution characteristics of water in pores with different scales as well as the influence of water on pore structures. The results showed that the adsorption mechanism of water vapor undergoes a transition from monolayer to multilayer to condensation with the increase in relative humidity (RH). The occurrence characteristics of adsorbed water in coal pores are controlled by the RH and pore size. When the RH is increased from 0 to 98%, the nitrogen adsorption capacity, specific surface area, and effective pore volume of the samples were all decreased significantly due to the different adsorption modes of water, which is more significant in pores with d < 10 nm. Additionally, the relative pressure corresponding to the branching position of the nitrogen adsorption-desorption curve will be changed with the increase in moisture content. Based on this, it is calculated that the adsorbed water will change the smoothness of the pore wall and the complexity of the pore structure.

Development and performance evaluation of alkali-activated multiple solid waste-based building foam insulation materials

To reduce building environmental pollution and energy consumption has become the mainstream development trend of today’s society. The building foam insulation materials (SWFIM) was developed by using blast furnace slag (BSF), waste photovoltaic glass (WPG), rice husk ash (RHA), and plant ash (PA), and the corresponding preparation technologies were proposed. The dry density, thermal conductivity, compressive strength, volumetric water absorption and pore structure parameters of SWFIM were measured. The effects of the amount of hydrogen peroxide solution (HPS), foam stabilizer (FS) and polyethylene (PE) fiber on the basic properties of SWFIM were discussed. The microscopic morphology of SWFIM was characterized by SEM (Scanning electron microscope) technology, and the mechanism of three influencing factors were revealed. The relationship between the basic properties of SWFIM was discussed and the corresponding prediction models were established. The test results showed that the effects of HPS and FS on the basic properties of SWFIM were complementary. When the amount of HPS and FS was 10 % and 1 %, respectively, SWFIM have achieved encouraging performance. PE fiber had different degrees of negative effects on the thermal properties of SWFIM, and the negative effects gradually increased with the increase of PE fiber content. The improvement effect of PE fiber on the compressive strength of SWFIM changes from positive influence to negative influence with the fiber content. When the fiber content increased to 0.6 %, the improvement effect was most obvious, increased by about 12.20 %. Statistics showed that the thermal conductivity and compressive strength of SWFIM were 0.0497 ∼ 0.0581 W/(m·K) and 0.33 ∼ 0.52 MPa, respectively. This showed that SWFIM was expected to become a potentially competitive building insulation material.

Study on the Nonlinear Permeability Mechanism and Pore Structure Characteristics of Deep Confined Aquifers

The study of deep soil mechanics is the basis of deep shaft construction. Exploring the nonlinear permeability mechanism of deep confined aquifers in depth is the prerequisite and foundation for carrying out calculations of the hydrophobic consolidation settlement of thick alluviums and preventing and controlling deep-well-damage disasters. Against the background of shaft damage caused by hydrophobic consolidation settlement of the bottom aquifer of thick alluviums, a joint HPLTC-HPPNP (high-pressure long-term consolidation and high-pore-pressure nonlinear permeability) test was carried out on the bottom aquifer of thick alluviums based on the ETAS test system. This paper studied the evolution law of the permeability coefficient (kv) of bottom aquifers under different heads of confined water, confining pressures (σr), permeability hydraulic gradients (i) and loading–unloading methods. The internal pore structure characteristics of clayey sand were obtained by using low-field nuclear magnetic resonance (NMR) technology to explore the clayey sand’s nonlinear permeability micro-mechanism. The research results showed that the bottom aquifer seepage volume (ΔQi) under high stress is affected by the head pressure difference and pore water dissipation, and kv decreases with an increasing σr according to the power function relationship. The influence of the hydraulic gradient (i) on kv is significantly influenced by σr. When σr &lt; 4 MPa, kv decreased with an increasing i, and when σr &gt; 4 MPa, kv increased with an increasing i first, then decreased, before then tending to be stable. Under different stress states, the T2 spectrum of clayey sand showed a bispectrum peak type, and the adsorbed water content decreased linearly with an increasing σr, while the capillary water decreased according to the power function. The content of capillary water in the permeable pores plays a key role in the permeability of clayey sand, and it has a power function relationship with σr. The research results of this paper provide a good experimental method for the study of deep soil permeability characteristics and parameter determination, provide a theoretical basis for deep alluvial hydrophobic consolidation and settlement, and further make up for the shortcomings of existing deep soil mechanics in permeability characteristics.

Soil Water Retention and Pore Characteristics of Intact Loess Buried at Different Depths

Surface water infiltration is a primary factor responsible for engineering challenges and geological disasters on the Loess Plateau of China (LPC). Due to the extensive groundwater in this region, surface water must pass through thick unsaturated zones to recharge the groundwater reservoirs. Exploring the unsaturated hydraulic characteristics of loess, especially at varying depths, may significantly contribute to disaster prevention and mitigation and the pursuit of sustainable development in the Loess Plateau. The soil-water characteristic curve (SWCC), intricately linked to the soil’s pore structure, is a critical hydraulic parameter of loess. An exploration well with a depth of 30 m was excavated in the LPC to obtain intact specimens at depths of 5 m, 15 m, and 25 m. Basic physical property tests, SWCC measurements, and particle size distribution (PSD) analyses were conducted. Additionally, the relationship between PSD and SWCC is discussed in this paper. The findings highlight the influence of depth on the dominant pore size and distribution density, both of which decreased with increasing depth. The air occlusion value of the SWCC experienced an increase, and the slope of the SWCC in the transition zone exhibited consistency. These observations underscore the pivotal role played by pore structure in shaping the soil’s water-retention behavior. Furthermore, predictions based on PSD data demonstrated excellent accuracy in replicating the wetting SWCC of loess over a wide suction range (e.g., 10–104 kPa).

Numerical Analysis of the Freezing Behavior of Saturated Cementitious Materials with Different Amounts of Chloride.

The freezing behavior of cement paste saturated with different chloride concentrations is investigated numerically with a coupled 3D hygro-thermo-mechanical FE analysis. The mathematical formulation of the freezing processes in the context of poromechanics takes into account the water (hydraulic) and ice pore pressures, as well as the distribution of heat (temperature) and strains. These quantities are calculated numerically based on three coupled differential equations, namely the static equilibrium equation and the equations for the transport of water and heat. The coupling between the mechanical (loading) and the non-mechanical processes (freezing) is performed using a staggered solution scheme. The proposed numerical approach is first validated using numerical and experimental studies from the literature dealing with two different cement pastes saturated with different amounts of chloride. The validated model is then used to investigate the effects of liquid water permeability, total porosity and pore size distribution on the freezing behavior of hardened cement paste. The results show that liquid water permeability has a strong effect on the pore pressure and deformation of the hardened cement paste. It is also shown that by decreasing the total porosity, the material becomes denser and contracts more as the temperature decreases, leading to a decrease in freezing strain. The results of this paper will provide important findings for the development of a simplified engineering model to investigate the mechanism that leads to freeze-thaw salt-induced damage to concrete structures in the framework of the DFG-funded research project.

Influence of wastepaper sludge ash as partial cement replacement on the properties of lightweight foamed concrete

This study focused on the effect of using wastepaper sludge ash (WPSA) as a partial substitute for cement in the production of lightweight foamed concrete (LFC). The LFC was produced with a constant dry density of 1350 kg/m3 by controlling the foam content. In this study, six mixtures of LFC were produced using WPSA as a partial substitute of 0%, 5%, 10%, 15%, 20% and 25% of the cement mass. Setting time, spreading ability and density tests were performed immediately after the mixing process to evaluate the fresh LFC properties. Meanwhile, the compressive strength, flexural strength, cleavage tensile strength and modulus of the elasticity tests were performed at test ages 7, 14 and 28 days to evaluate the mechanical properties. Water absorption, capillary absorption, gas permeability, porosity and pore distribution were performed to evaluate the transport properties. Furthermore, SEM evaluation was performed to evaluate the microstructure. The inclusion of WPSA as a 15% partial cement replacement achieved the highest mechanical properties. The compressive strength was 11.2 MPa, the flexural strength was 2.61 MPa, the tensile strength was 1.72 MPa, and the elastic modulus was 3.253 GPa. Inclusion of WPSA as a partial substitute for cement with 25% led to the best transport properties by having the lowest water absorption and porosity by 17.4% and 37.75%, respectively.

Effects of thawing-induced softening on fracture behaviors of frozen rock

Due to the presence of ice and unfrozen water in pores of frozen rock, the rock fracture behaviors are susceptible to temperature. In this study, the potential thawing-induced softening effects on the fracture behaviors of frozen rock is evaluated by testing the tension fracture toughness (KIC) of frozen rock at different temperatures (i.e. −20 °C, −15 °C, −12 °C, −10 °C, −8 °C, −6 °C, −4 °C, −2 °C, and 0 °C). Acoustic emission (AE) and digital image correlation (DIC) methods are utilized to analyze the microcrack propagation during fracturing. The melting of pore ice is measured using nuclear magnetic resonance (NMR) method. The results indicate that: (1) The KIC of frozen rock decreases moderately between −20 °C and −4 °C, and rapidly between −4 °C and 0 °C. (2) At −20 °C to −4 °C, the fracturing process, deduced from the DIC results at the notch tip, exhibits three stages: elastic deformation, microcrack propagation and microcrack coalescence. However, at −4 °C–0 °C, only the latter two stages are observed. (3) At −4 °C–0 °C, the AE activities during fracturing are less than that at −20 °C to −4 °C, while more small events are reported. (4) The NMR results demonstrate a reverse variation trend in pore ice content with increasing temperature, that is, a moderate decrease is followed by a sharp decrease and −4 °C is exactly the critical temperature. Next, we interpret the thawing-induced softening effect by linking the evolution in microscopic structure of frozen rock with its macroscopic fracture behaviors as follow: from −20 °C to −4 °C, the thickening of the unfrozen water film diminishes the cementation strength between ice and rock skeleton, leading to the decrease in fracture parameters. From −4 °C to 0 °C, the cementation effect of ice almost vanishes, and the filling effect of pore ice is reduced significantly, which facilitates microcrack propagation and thus the easier fracture of frozen rocks.

Characterizing water transfer in compacted soils in the context of energy storage, contribution of magnetic resonance imaging (MRI)

The concept of energy geostructures consists in enhancing existing civil engineering structures from an energy point of view thanks to the insertion of heat exchanger tubes. In order to consider the use of compacted soil embankments for heat storage [1], a good knowledge of water movement is required. Indeed, the increase in temperature of the exchangers leads to a migration of liquid/vapour water to the surface layers [2]. A loss of moisture may alter the thermal capacity of the soil [1] and therefore the system energy efficiency. To determine unsaturated hydraulic properties, the Instantaneous Profile Method (IPM) consists in inducing transient flow in a long cylindrical sample of soil and then measuring the resulting water content and/or pore water pressure profiles at various time intervals [3]. The unsaturated hydraulic conductivity (ku) is then computed using Darcy’s law.&#x0D; The direct evaporation technique allows the measurement of the suction profile in a soil column submitted to drying [4] using filter papers whose water retention curve is known. This method is quite reliable but requires long equilibrium time. Thus, the tests need several weeks and do not give accurate results at the early stages of drying, as the soil state is close to saturation. The analysis of the results when the soil retention capacity is low is therefore complicated, especially when the flow is coupled with temperature variations.&#x0D; In this study, this classical method was compared to a faster alternate method using nuclear magnetic resonance imaging (MRI) that allows for non-intrusive, continuous and small-scale monitoring of the effect of thermo-hydraulic solicitations on water transfer within the sample. The use of MRI for monitoring the drying/wetting front progression appeared in 1970 [5]. Simpson et al. [6] presented the successive studies that have made it possible to develop a method for monitoring the movement of water within a sample. These measurements can be 1D, 2D and 3D.&#x0D; The tests were performed on a sandy lean clay sampled in the Paris region in France. The soil was dried, pulverized, and sieved through a 2 mm sieve before experiments. The compaction state was selected to optimize the heat storage capacity [4] with a water content of 16.3% and a dry density of 1.79 Mg.m-3. Ten cylindrical samples of 70 mm in diameter and 20 mm in height were compacted and superimposed with introducing filter paper disks between them. The regular weighting of each sample and each filter paper during three months allowed the derivation of the ku curve by the IPM method.&#x0D; For the MRI method, 9 samples of 36 mm in diameter and 10 mm in height were compacted at the initial state then brought to different degrees of saturation. The measurement of the water proton relaxation time using a Bruker Biospec 24/40 superconducting magnet (100 MHz), allowed the definition of a calibration curve which connects MRI signal to the water content of the samples (Figure 1b). A Single Point Imaging pulse sequence [7] was used to obtain the signal intensity (encoding time 75 µs &lt; t &lt; 200 µs). In an image acquired with the SPI method, the intensity of each voxel (S) is :&#x0D; (1) Whereis the magnetization in a pixel and is the transverse relaxation time.&#x0D; The calibration curve is shown in Figure 1b. Then, a larger sample of 30mm in height was compacted and exposed to an air flow at 20°C and 30% relative humidity through using a remote humid air generation system. 27 measurements points were monitored with an interval of 1.1 mm along the sample. Four examples of the recorded profiles are shown in Figure 1c. The evolution of the water content inside the sample is then calculated using the calibration curve to interpret the water migration in the samples submitted to humidity- and temperature-controlled air (Figure 1a). The pre-established retention curve of the soil will be used to calculate its matric suction. At each depth, the flow velocity and the hydraulic gradient will be calculated from the water content profiles and suction profiles respectively in order to determine the unsaturated hydraulic conductivity. &#x0D; These experimental developments allow the non-intrusive and continuous quantification of water movement in unsaturated soils during the application of coupled thermo-hydraulic solicitations. The understanding of these fundamental parameters is a key step for studying thermo-hydromechanical behavior of compacted soils considered for heat storage. The results provide insight into the feasibility of these structures in terms of their long-term energy efficiency and stability.

Surface tension of cementitious pore solutions at low atmospheric pressure: An experimental exploration

Currently, it is believed that surface tension increases with the reduction of atmospheric pressure, and the increased surface tension is considered as the primary cause of the decreased bubble stability in cement-based materials at low atmospheric pressure. However, this viewpoint lacks experimental verification due to the difficulty in measuring surface tension at low atmospheric pressure. This study systematically explores the effect of low atmospheric pressure (0∼0.1 MPa) on the surface tension of pore solutions of fresh cement pastes. The surface tension of pore solutions was measured at different atmospheric pressures by using the high-accuracy automatic interface tension meter. Results show that the impact of low atmospheric pressure on the surface tension of deionized water, cement and fly ash pore solutions is insignificant. Therefore, the decrease in bubble stability and air content of concrete at low atmospheric pressure cannot be attributed to the change of surface tension. The effect of low atmospheric pressure on the surface tension of air-liquid interface is explained from the perspective of intermolecular force and density. This research helps to better understand the impact of low atmospheric pressure on surface tension and lays the essential groundwork for improving bubble stability of cement-based materials in high-altitude regions.

Investigating the Impact of Aqueous Phase on CO2 Huff ‘n’ Puff in Tight Oil Reservoirs Using Nuclear Magnetic Resonance Technology: Stimulation Measures and Mechanisms

Summary CO2 huff ‘n’ puff is a promising enhanced oil recovery (EOR) technique for tight/shale reservoirs, also enabling CO2 geological storage. However, the effectiveness of this method can be significantly affected by the aqueous phase resulting from connate water and hydraulic fracturing. The mechanism underlying the influence of the aqueous phase on oil recovery during CO2 huff ‘n’ puff, as well as the corresponding stimulation methods in such scenarios, remain unclear and warrant further study. To investigate this, we utilized a nuclear magnetic resonance (NMR) instrument to track the movement of fluids during CO2 huff ‘n’ puff under water invasion conditions. The impact of the invaded aqueous phase on oil recovery was examined, and the impact of different treatment parameters was explored. The results show that the aqueous barrier formed by water invasion alters the pathway of CO2 diffusion to matrix oil. This alteration leads to a diminished concentration of CO2 in the oil phase, which, in turn, results in a substantial reduction in oil recovery. Consequently, the performance of CO2 huff ‘n’ puff is highly sensitive to the water phase. Nevertheless, the oil recovery dynamics in cyclic CO2 huff ‘n’ puff under water invasion exhibit distinctive patterns compared with those without water invasion. These differences manifest as notable low oil recovery in the first cycle, followed by a rapid increase in the second cycle. This behavior primarily arises from the expulsion of a significant portion of the invaded water from the macropores after the first cycle. However, the effectiveness of this mechanism is limited in micropores due to the challenging displacement of trapped water in such pores. Raising the injection pressure mainly boosts oil recovery in macropores, with minimal response in micropores. Yet, the achievement of miscibility does not lead to a substantial improvement in the CO2 huff ‘n’ puff performance, primarily due to the constraints imposed by the limited CO2 dissolution through molecular diffusion Additionally, we have proposed three stimulation mechanisms achieved by lengthening the soaking time under water invasion conditions. First, the prolonged soaking time increases the concentration of CO2 molecules that diffuse into the matrix oil. Second, it promotes the imbibition of the trapped water on the fracture surface into the deeper matrix to alleviate water blockage. Finally, the invaded water in macropores displaces oil in micropores by capillary force during the soaking period.

Macroscale insights into heterogeneous hydrate formation and decomposition behaviors in porous media

Hydrocarbon fuels are distributed unevenly in the earth, known as heterogeneity. How to harness the nature of heterogeneity for sustainable development of energy sources is the key issue. Herein, the controllable process of heterogeneous hydrate phase transition is firstly realized at macroscale, and three typical hydrate distribution patterns (dispersed, massive, and layered) with the same hydrate saturation are successfully achieved. Macroscale observations revealed the kinetic of heterogeneous hydrate phase transition governed by water and gas transfer in pores. Specifically, a new sequence of “nucleation-growth-migration” driven by water migration for heterogeneous hydrate formation in porous media is proposed. In contrast, gas transportation capacity and reformation probability determine the heterogeneous hydrate decomposition efficiency. Significantly, the phase transition rates between heterogeneous and homogeneous hydrate differs by 2 to 3 times due to mass migration. These results suggest that the porous sediments with facilitated water migration under strong capillary effect are preferable for heterogeneous distribution of hydrocarbon fuels, providing explanations for the enrichment of methane hydrate in marine coarse-grained sandy sediment. Nevertheless, the distribution heterogeneity could be challenging to efficient and economic gas production, raising the demand for targeted approaches to develop natural gas hydrate with different distribution patterns. More significantly, the enhanced hydrate formation rate in porous media by controllable heterogeneous hydrate formation method offered by this work also indicates the feasibility in hydrocarbon capture, storage and transport via hydrate-based technologies.

Molecular simulations reveal that heterogeneous ice nucleation occurs at higher temperatures in water under capillary tension

Abstract. Heterogeneous ice nucleation is thought to be the primary pathway for the formation of ice in mixed-phase clouds, with the number of active ice-nucleating particles (INPs) increasing rapidly with decreasing temperature. Here, molecular-dynamics simulations of heterogeneous ice nucleation demonstrate that the ice nucleation rate is also sensitive to pressure and that negative pressure within supercooled water shifts freezing temperatures to higher temperatures. Negative pressure, or tension, occurs naturally in water capillary bridges and pores and can also result from water agitation. Capillary bridge simulations presented in this study confirm that negative Laplace pressure within the water increases heterogeneous-freezing temperatures. The increase in freezing temperatures with negative pressure is approximately linear within the atmospherically relevant range of 1 to −1000 atm. An equation describing the slope depends on the latent heat of freezing and the molar volume difference between liquid water and ice. Results indicate that negative pressures of −500 atm, which correspond to nanometer-scale water surface curvatures, lead to a roughly 4 K increase in heterogeneous-freezing temperatures. In mixed-phase clouds, this would result in an increase of approximately 1 order of magnitude in active INP concentrations. The findings presented here indicate that any process leading to negative pressure in supercooled water may play a role in ice formation, consistent with experimental evidence of enhanced ice nucleation due to surface geometry or mechanical agitation of water droplets. This points towards the potential for dynamic processes such as contact nucleation and droplet collision or breakup to increase ice nucleation rates through pressure perturbations.

Selective Water Pore Recognition and Transport through Self-Assembled Alkyl-Ureido-Trianglamine Artificial Water Channels.

In nature, aquaporins (AQPs) are proteins known for fast water transport through the membrane of living cells. Artificial water channels (AWCs) synthetic counterparts with intrinsic water permeability have been developed with the hope of mimicking the performances and the natural functions of AQPs. Highly selective AWCs are needed, and the design of selectivity filters for water is of tremendous importance. Herein, we report the use of self-assembled trianglamine macrocycles acting as AWCs in lipid bilayer membranes that are able to transport water with steric restriction along biomimetic H-bonding-decorated pores conferring selective binding filters for water. Trianglamine [(±)Δ, (mixture of diastereoisomers) and (R,R)3Δ and (S,S)3Δ], trianglamine hydrochloride (Δ.HCl), and alkyl-ureido trianglamines (n = 4, 6, 8, and 12) [(±)ΔC4, (±)ΔC8, (±)ΔC6, and (±)ΔC12] were synthesized for the studies presented here. The single-crystal X-ray structures confirmed that trianglamines form a tubular superstructure in the solid state. The water translocation is controlled via successive selective H-bonding pores (a diameter of 3 Å) and highly permeable hydrophobic vestibules (a diameter of 5 Å). The self-assembled alkyl-ureido-trianglamines achieve a single-channel permeability of 108 water molecules/second/channel, which is within 1 order of magnitude lower than AQPs with good ability to sterically reject ions and preventing the proton transport. Trianglamines present potential for engineering membranes for water purification and separation technologies.

In-situ utilization of EPS improves the directional oxidation ability of Fe(III)/H2O2 and enhances sludge dewaterability

Inefficient sludge dewatering can result in high costs for sludge treatment and disposal, as well as increased pollution of the environment. In this study, we constructed a double oxidation–reduction (Redox) cycle system of Fe(II)/Fe(III) and Fe(II)-extracellular polymeric substance (EPS)/Fe(III)-EPS by utilizing EPS in situ and collaborating with Fe (III) and H2O2 so as to regulate the performance of Fenton oxidation for efficiently enhancing the dewaterability. Results displayed the specific resistance to filtration (SRF) reduced from 34.1 ± 2.4 × 1012 m/kg to 16.2 ± 1.5 × 1012 m/kg with only 0.15 mmol Fe(III)/g VSS and 1.46 mmol H2O2/g VSS. Notably, the formation of relative stable Fe(III)-EPS complex was found under the interval addition of Fe(III) and H2O2. Four types of reactive species (hydroxyl radical (•OH), singlet oxygen (1O2), superoxide radical (O2•-) and Fe(IV)) which could effective destroy EPS structure during conditioning process, were generated after the addition of H2O2. It effectively promoted the transition from intracellular oxidation to extracellular oxidation under Fenton oxidation conditions, which reduced negative effects of cell lysis under excessive oxidation during sludge conditioning. The structure of EPS damaged significantly during the oxidation process, leading to the effective conversion of bound water to free water. Meanwhile, the existence of dissociative Fe(III) promoted the aggregation of sludge flocs, generating large channels or pores for sludge water to discharge, and then improving the dewaterability. Overall, [Fe(III)-EPS]/H2O2 treatment as an efficient sludge conditioning method can provide guidance for sludge dewaterability enhancement in urban sludge treatment and disposal.

Distribution and dynamics of water in the blended pastes unraveled by thermoporometry and dielectric properties

Water distribution in hardened paste and its dynamics determine many properties related to durability. Moisture distribution was determined by thermoporometry combined with vacuum drying. Dynamics of confined water were measured by broadband dielectric spectroscopy. Water in pores <2.4 nm cannot form tetrahedral ice structure due to geometrical constraints. The volume of unfrozen water (in interlayer and gel pores) decreases after the drying at all relative humidity levels. An evident coarsening of gel pores occurs with drying between 75 % and 55 % RH. 35 % fly ash and slag have limited effects on relaxation processes of silanol hydroxyl groups and interlayer water. However, they slow down the dynamics of water in small gel pores, thereby enhancing interactions between water and the solid interface. This study clarifies the microstructural changes during the drying and reveals the sensitivity of water dynamics to the chemical environment in C-S-H of blended pastes.

Experimental study on infrared thermal response characteristics of water-bearing concrete under drop hammer impact

The dynamic impact damage of concrete will lead to serious safety accidents, and the water environment will aggravate the degree of damage. In this paper, an infrared monitoring experimental system for drop hammer impact damage of water-bearing concrete was designed and established. The mechanical properties, infrared radiation temperature (IRT) and infrared thermography of concrete impact damage with different soak time were tested and analyzed. The influence of water on the infrared generation mechanism of concrete was discussed. The results show that water has an initial weakening effect on concrete, which weakens the cementation between concrete particles and aggregate strength, resulting in a decrease in concrete strength. Compared with dry concrete, the infrared temperature of water-bearing concrete increased more during impact damage. With the increase of soak time, the average infrared temperature (AIRT) and the maximum infrared temperature (MIRT) of water-bearing concrete decreased. When dry concrete was damaged, tensile cracks were mainly produced and accompanied by heat absorption. When water-bearing concrete was damaged, high temperature shear cracks appeared. The high temperature generated at the moment of impact failure of water-bearing concrete may be caused by the cavitation phenomenon of water in the microscopic pores of concrete during the drop hammer impact and the combined effect of concrete microstructure damage. The research results are of great significance for monitoring and evaluating the stability of the dynamic evolution process of concrete structures.

Leaf hydathode occurrence in indigenous New Zealand angiosperm trees: a preliminary survey

ABSTRACT Toothed leaf margins are common (∼36%) in the New Zealand indigenous flora, and are most abundant in cool forests with high rainfall. Toothed margins are often associated with hydathodes, specialised structures that release water and solutes to maintain positive xylem pressure. However, the presence of hydathodes is mainly known from herbaceous plants. Here we investigate the presence and morphology of hydathodes in indigenous woody species representing 25 families, 33 genera and 57 species, with toothed and entire leaf margins. We tested whether toothed leaf margins on predominantly evergreen species are associated with hydathodes. Two types of structures on leaves were recognised: laminar hydathodes, water pores larger than normal stomata and associated with veins, and hydathodes positioned at the terminus of leaf teeth serviced by principal veins. Laminar hydathodes occur more frequently, but not exclusively, on toothed leaves (on 61.8% of toothed species vs. 48.0% of entire-margined species). Leaf tooth hydathodes are complex structures with undifferentiated, porous tissue plugs linked to splayed vein termini of vessel elements and often form a distinctive cap on leaf teeth. Tooth hydathodes occur on ∼90% of the serrated leaves species sampled. Ontogenetic differences in hydathode occurrence were noted in Alectryon excelsus as leaf morphology changes with plant age from a serrated to a non-serrated form. Quintinia acutifolius showed a similar pattern between individuals with different leaf morphologies. In our sampled dataset, tree species with any type of hydathode occur in areas with a higher ratio of rainfall to potential evapotranspiration than tree species without hydathodes. This pattern was not observed in shrubs. The strong association between marginal hydathodes and toothed leaves in New Zealand trees, plus the association with higher rainfall environments, suggests that these structures function to release hydraulic water pressure in plants on periodically saturated soils in high rainfall zones.

Reducing the Invasiveness of Low- and High-Grade Endometrial Cancers in Both Primary Human Cancer Biopsies and Cell Lines by the Inhibition of Aquaporin-1 Channels.

Aquaporin (AQP) channels in endometrial cancer (EC) cells are of interest as pharmacological targets to reduce tumor progression. A panel of compounds, including AQP1 ion channel inhibitors (AqB011 and 5-(phenoxymethyl) furan-2-carbaldehyde, PMFC), were used to test the hypothesis that inhibition of key AQPs can limit the invasiveness of low- and high-grade EC cells. We evaluated the effects on transwell migration in EC cell lines (Ishikawa, MFE-280) and primary EC cells established from surgical tissues (n = 8). Quantitative PCR uncovered classes of AQPs not previously reported in EC that are differentially regulated by hormonal signaling. With estradiol, Ishikawa showed increased AQPs 5, 11, 12, and decreased AQPs 0 and 4; MFE-280 showed increased AQPs 0, 1, 3, 4, 8, and decreased AQP11. Protein expression was confirmed by Western blot and immunocytochemistry. AQPs 1, 4, and 11 were colocalized with plasma membrane marker; AQP8 was intracellular in Ishikawa and not detectable in MFE-280. AQP1 ion channel inhibitors (AqB011; PMFC) reduced invasiveness of EC cell lines in transwell chamber and spheroid dispersal assays. In Ishikawa cells, transwell invasiveness was reduced ~41% by 80 µM AqB011 and ~55% by 0.5 mM 5-PMFC. In MFE-280, 5-PMFC inhibited invasion by ~77%. In contrast, proposed inhibitors of AQP water pores (acetazolamide, ginsenoside, KeenMind, TGN-020, IMD-0354) were not effective. Treatments of cultured primary EC cells with AqB011 or PMFC significantly reduced the invasiveness of both low- and high-grade primary EC cells in transwell chambers. We confirmed the tumors expressed moderate to high levels of AQP1 detected by immunohistochemistry, whereas expression levels of AQP4, AQP8, and AQP11 were substantially lower. The anti-invasive potency of AqB011 treatment for EC tumor tissues showed a positive linear correlation with AQP1 expression levels. In summary, AQP1 ion channels are important for motility in both low- and high-grade EC subtypes. Inhibition of AQP1 is a promising strategy to inhibit EC invasiveness and improve patient outcomes.