Absorbed Water Mass Research Articles

Capillary Imbibition Laws of Fresh–Brackish Waters in Sandstone

Understanding the capillary imbibition laws of brackish water in rocks is necessary to reveal the mechanism of fluid, salt, and ion transport. In this study, we investigated the capillary imbibition laws of a Na2SO4 solution of different concentrations in sandstone by measuring the parameters of water absorption mass, water migration front height, nuclear magnetic resonance (NMR) T2 spectra, and stratified moisture distribution. The results indicate the following: (1) With an increase in the salt solution concentration, the water absorption rate of samples increases, specifically manifested in an increase in the rate of absorption mass and a rising rate of the absorption front. (2) With an increase in the salt solution concentration, the total NMR signals in samples measured at the end of water absorption decreases; that is, the total amount of water absorption decreases. (3) When the solution concentration exceeds 0.50 g/L, variations in the NMR signal of samples and the absorbed water mass over time are not synchronic and are even opposite at some stages. Based on the capillary dynamic theories of liquid, the influence of salts on solution properties and the modification of the pore structure by crystallization are considered when discussing the underlying mechanism of capillary imbibition in sandstone. By calculating the physical properties such as the density, viscosity, surface tension, and contact angle of solutions with different concentrations, the imbibition process does not exhibit any significant variation with the difference in the properties of the liquid. The equivalent capillary radii of the samples at varying salt concentrations are obtained by fitting the capillary dynamics curves with the theoretically calculated values. The equivalent capillary radii of samples in higher salt concentrations are larger, i.e., the difference in capillary imbibition laws introduced by the salt concentration should be attributed to modifications to the pore structure caused by salt crystallization.

Microencapsulation of 2-phenyl ethanol with methylcellulose/alginate/methylcellulose as the wall material and stability of the microcapsules

In this study, 2-phenyl ethanol (2-PEA) was microencapsulated with natural and semisynthetic carbohydrate polymers as the wall material. The wall material components methylcellulose (MC), alginate sodium (ALG), and carboxymethyl chitosan were optimized according to the results of microscopy images, zeta potential, and 2-PEA content. The combination of MC/ALG/MC was selected as the best wall components. Cobalt chloride (CoCl2) was used as the core material to prepare microcapsules whose color was measured with a colorimeter to intuitively express the water absorption of the microcapsules. The absorbed water mass and b* were related to one variable quadratic equation. The rapid release properties and the natural long-term release properties of 2-PEA microcapsules were measured.

Correction: Statistical degradation modelling of Poly(D,L-lactide-co-glycolide) copolymers for bioscaffold applications.

[This corrects the article DOI: 10.1371/journal.pone.0204004.].

Statistical degradation modelling of Poly(D,L-lactide-co-glycolide) copolymers for bioscaffold applications.

This methodology permits to simulate the performance of different Poly(D,L-lactide-co-glycolide) copolymer formulations (PDLGA) in the human body, to identify the more influencing variables on hydrolytic degradation and, thus, to estimate biopolymer degradation level. The PDLGA characteristic degradation trends, caused by hydrolysis processes, have been studied to define their future biomedical applications as dental scaffolds. For this purpose, the mass loss, pH, glass transition temperature (Tg) and absorbed water mass of the different biopolymers have been obtained from samples into a phosphate-buffered saline solution (PBS) with initial pH of 7.4, at 37°C (human body conditions). The mass loss has been defined as the variable that characterize the biopolymer degradation level. Its dependence relationship with respect to time, pH and biopolymer formulation has been modelled using statistical learning tools. Namely, generalized additive models (GAM) and nonlinear mixed-effects regression with logistic and asymptotic functions have been applied. GAM model provides information about the relevant variables and the parametric functions that relate mass loss, pH and time. Mixed effects are introduced to model and estimate the degradation properties, and to compare the PDLGA biopolymer populations. The degradation path for each polymer formulation has been estimated and compared with respect to the others for helping to use the proper polymer for each specific medical application, performing selection criteria. It was found that the mass loss differences in PDLGA copolymers are strongly related with the way the pH decay versus time, due to carboxylic acid groups formation. This may occur in those environments in which the degradation products remain relatively confined with the non degraded mass. This is the case emulated with the present experimental procedure. The results show that PDLGA polymers degradation degree, in terms of half life and degradation rate, is increasing when acid termination is included, when DL-lactide molar ratio is reduced, decreasing the midpoint viscosity, or when glycolide is not included.

Waterproof Performances of CNT Cement-based Composites Modified by Doped Silane Waterproofing Agent

We integrated orthogonal experiment technique with three factors and three levels, and employed single-surface capillary absorption method to study the effects of water-cement ratio (W/C), the loading of carbon nanotube (wCNT), the addition of silane waterproofing agent (wKH55) on the waterproof performances of CNT cement-based materials modified by doped silane waterproofing agent (KH/CNT/CC). Orthogonal range analysis reveals, when the KH/CNT/CC specimen is in condition of W/C=0.32, wCNT=0.2%, wKH55=0.5%, the mass of water absorption is the minimum, and the water resistance is the best. The absorbed water mass after 96h of KH/CNT/CC with wKH55=0.5% is decreased by 170.1g/m2 when compared with the case with wKH55=0.1%, the incorporation of silane waterproofing agent has effectively improve the impermeability of CNT cement-based composites. This will provide a reference for the development of the intrinsic sensors with excellent waterproof performance.

Capillary imbibition of water in discrete planar cracks

Knowledge of capillary imbibition of water in distributed microcracks within building materials plays a critical role in assessing and predicting the durability of reinforced concrete structures. This paper focuses on a comprehensive investigation of capillary imbibition of water in discrete planar cracks, involving both theoretical and experimental aspects. In view of dynamic capillary flow of liquid in discrete cracks, which is usually described by Lucas-Washburn (L-W) equation, the correlation between capillary rise height and crack width is theoretically established. A benchmark study to investigate capillary flow in a series of discrete granite cracks, artificially fabricated by means of ultrathin steel disc with various thicknesses, is reported, and this provides data to validate the theoretical model developed in the paper. The experimental results give out the measurement of discrete crack width with different sizes (23.64–240.38μm) as well as the mass of absorbed water obtained by the traditional gravimetric method. The average cumulative water mass of specimen generally increases with an increase of crack width for the ranges studied. Moreover, the cumulative water mass rapidly increases at the initial stage of water absorption test while at later stage the variation of absorbed water mass is relatively less. The analysis shows that the influence of gravity on the variation of capillary rise height is remarkable when crack width is beyond a critical range. Finally, the comparison between experimental and theoretical results indicates that the L-W capillary imbibition model of porous capillary tube after taking into account the gravity effect can be applied to the case of discrete crack with a certain range of width.

Hydration-Induced Phase Transitions in Surfactant and Lipid Films.

For several surfactant and lipid systems, it is crucial to understand how hydration influences the physical and chemical properties. When humidity changes, it affects the degree of hydration by adding or removing water molecules. In many cases, this process induces transitions between liquid crystalline phases. This phenomenon is of general interest for numerous applications simply because of the fact that humidity variations are ubiquitous. Of particular interest are hydration-induced phase transitions in amphiphilic films, which in many cases appear as the frontier toward a vapor phase with changing humidity. Considering this, it is important to characterize the film thickness needed for the formation of 3D liquid crystalline phases and the lyotropic phase behavior of this kind of film. In this work, we study this issue by employing a recently developed method based on the humidity scanning quartz crystal microbalance with dissipation monitoring (HS QCM-D), which enables continuous scanning of the film hydration. We investigate five surfactants films (DDAO, DTAC, CTAC, SDS, and n-octylβ-d-glucoside) and one lipid film (monoolein) and show that HS QCM-D enables the fast characterization of hydration-induced phase transitions with small samples. Film thicknesses range from tens to hundreds of nanometers, and clear phase transitions are observed in all cases. It is shown that phase transitions in films occur at the same water activities as for corresponding bulk samples. This allows us to conclude that surfactant and lipid films, with a thickness of as low as 50 nm, are in fact assembled as 3D-structured liquid crystalline phases. Furthermore, liquid crystalline phases of surfactant films show liquidlike behavior, which decreases the accuracy of the absorbed water mass measurement. On the other hand, the monoolein lipid forms more rigid liquid crystalline films, allowing for an accurate determination of the water sorption isotherm, which is also true for the sorption isotherms corresponding to the solid surfactant phases.

An Alternate Test Method for the Void Content of Pervious Concrete

Abstract In recent years, pervious concrete has become an emerging material for healthier ground water recharge and superior control of high stormwater runoff. This is facilitated by the high void content of the material. The void content percentage is an important design variable, as it correlates permeability as well as the strength of the material. Therefore, an accurate quantification of the void content is needed. A recently developed ASTM standard (ASTM C1754/C1754M-12) presents a method for determining the density and void content of hardened pervious concrete; however, there are still some issues apparent with this standard. The main issue is that the standard does not consider the absorption of the aggregate or the paste, which could adversely affect the results. Other concerns include the buoyant force due to trapped air when submerging the specimens, the high drying temperature in drying method B, which causes cracking and renders the specimen unusable for other testing, and the lengthy time requirement. This study further articulated these issues and presented two alternative testing techniques, one novel technique (Torres method) and one modified ASTM C1754 test method that can be used to better determine the void content of pervious concrete. The Torres method developed in this study placed the pervious concrete specimen in saturated surface dry (SSD) condition prior to determining the void percentage, such that the absorbed water mass was removed from the calculation. Additionally, a modified ASTM C1754 was developed that also placed the specimens in an SSD condition while still using the water tank used in ASTM C1754. The results from both of the developed methods showed lower void percentages for the specimens tested than with the current ASTM C1754 (drying method A and B) standard. The results indicated that including the absorbed water mass into the calculation ultimately resulted in higher void percentages.

Comparative analysis of hygroscopic properties of atmospheric aerosols at ZOTTO Siberian background station during summer and winter campaigns of 2011

The results of measurements of hygroscopic properties and chemical analysis of atmospheric aerosol samples collected from June 10 to 20 and December 15 to 25, 2011, at the ZOTTO background stations (60.8° N, 89.35° E) in Central Siberia are presented. The sorption properties of aerosols are studied with the help of a differential analyzer of absorbed water mass in the relative humidity range of 5 to 99%. It has been found that the hygroscopic growth factor of aerosol particles collected during the winter campaign is on average 45% higher than that of the aerosol collected in the summer campaign, which leads to a 40% decrease in the critical supersaturation threshold of cloud activation of particles. The measurement data are analyzed and parameterized using a new approach that takes into account the concentration effects in the particle—water vapor system at low humidities. Based on the chemical analysis, the content of water-soluble substances in the winter sample is 2.5 times higher than in the summer sample. Here, the amount of sulfates and nitrates increases 20 and 88 times, respectively. A trajectory analysis of air mass motion shows that the increased content of inorganic ions in aerosols for the winter sample is caused by long-range transport of pollutants from industrial areas of Siberia. This difference in the chemical composition is the main source of the observed difference in hygroscopic and condensation properties of the aerosol particles.

Effects of exogenous hormones on leaf photosynthesis of Panax ginseng

Ginseng (Panax ginseng) is a typical perennial shade plant. Aim of this study was to investigate the effects of exogenous hormones on photosynthesis of P. ginseng. At different growth stages, the aerial parts of P. ginseng plants were cut at the stem base and they were inserted into the nutrient solutions containing different exogenous hormones. Then the leaf photosynthesis and water absorbing capacity (absorbing water mass) of the excised plants were measured. The results showed that exogenous abscisic acid (ABA) decreased significantly net photosynthetic rate (P N), stomatal conductance, transpiration rate, and absorbed water mass of excised P. ginseng at all growth stages, while both cytokinin (CTK) and indole-3-acetic acid (IAA) enhanced those parameters. Comparing different growth stages, ABA caused more severe inhibition of leaf photosynthesis at the early growth stage, while CTK and IAA showed significant enhancement of leaf photosynthesis at later growth stage. ABA reduced highly intercellular CO2 concentration of P. ginseng at the flowering and green fruit stages, but it had only a small effect at red fruit early and red fruit stages. During the early growth stage, the inhibitory effect of ABA on leaf P N might be caused mainly due to the stomatal limitation. However, the reason for this reduction was complex at the later growth stage and it included stomatal and other factors.