H2O Penetration Research Articles

A multi-scale investigation on recycled ceramic and rubber composite cement-based materials: Acoustic emission, NMR, molecular dynamics simulation

Utilizing construction waste has become a promising way to reduce carbon emissions and energy consumption. This study systematically investigated the application potential of ceramics waste aggregate (CWA) in rubber cement-based materials from the macro-micro-nano scale. The results show that CWA and rubber particles can synergistically enhance the mechanical strength and ductility of mortar. The 28-day compressive and flexural strength of composite mortar increased by 42.9% and 33.3%, respectively. The active pozzolanic components (SiO2, Al2O3) of CWA induce the secondary hydration reaction, and the cement hydration degree could be increased by 33.8% at 28 days. Furthermore, the "charge non-conservation phenomenon" driven by Si4+ and Al3+ promotes the polymerization of the three-dimensional gel network, increasing the proportion of Q3 and Q4 species. The penetration of H2O, Ca2+, and silicon chains into the CWA crystals strengthens the mechanical coupling between the slurry and the aggregate at the nano-scale. Nevertheless, the deterioration of workability and the bonding slip of ceramic glaze increase the brittleness of mortar.

Determination of divalent metal ion-regulated proton concentration and polarity at the interface of anionic phospholipid membranes.

We studied the influence of trace quantities of divalent metal ions (M2+: Ca2+, Mg2+, and Zn2+) on proton concentration (-log[H+], designated as pH') and polarity at the interface of anionic PG-phospholipid membranes comprising saturated and unsaturated acrylic chains. A spiro-rhodamine-6G-gallic acid (RGG) pH-probe was synthesized to monitor the interfacial pH' of large unilamellar vesicles (LUVs) at a physiologically appropriate bulk pH (6.0-7.5). 1H-NMR spectroscopy and fluorescence microscopy showed that RGG interacted with the LUV interface. The pH-dependent equilibrium between the spiro-closed and spiro-open forms of RGG at the interface from the bulk phase was compared using fluorescence spectra to obtain interfacial pH'. Interfacial dielectric constant (κ) was estimated using a porphyrin-based polarity-probe (GPP) that exhibits a κ-induced equilibrium between monomeric and oligomeric forms. M2+ interaction decreased LUV interfacial κ from ∼67 to 61, regardless of lipid/M2+ types. Fluorescence spectral and microscopic analysis revealed that low Ca2+ and Mg2+ amounts (M2+/lipid = 1 : 20 for unsaturated DOPG and POPG and ∼1 : 10 for saturated DMPG lipids), but not Zn2+, decreased LUV interfacial acidity from pH' ∼3.8 to 4.4 at bulk pH 7.0. Although membrane surface charges are normally responsible for pH' deviation from the bulk to the interface, they cannot explain M2+-mediated interfacial pH' increase since there is little change in surface charges up to a low M2+/lipid ratio of <1/10. M2+-induced tight lipid headgroup packing and the resulting increased surface rigidity inhibit interfacial H+/H2O penetration, reducing interfacial acidity and polarity. Our findings revealed that in certain cases, essential M2+ ion-induced bio-membrane reactivity can be attributed to the influence of interfacial pH'/polarity.

Hydration inhibition mechanism of gypsum on tricalcium aluminate from ReaxFF molecular dynamics simulation and quantum chemical calculation

ABSTRACT To understand the hydration inhibition mechanism of gypsum (CaSO4·2H2O) on tricalcium aluminate (C3A), the very early hydration process of C3A in the presence of CaSO4·2H2O was investigated by ReaxFF molecular dynamics simulation and quantum chemical calculation. The adsorption propensity of H2O to the surface of CaSO4·2H2O and C3A, the penetration of H2O into CaSO4·2H2O and C3A, the diffusion of CaSO4·2H2O and C3A to H2O, and the structural changes at the interface of C3A were investigated by analyzing the adsorption configuration, penetration depth, diffusion distance, and the radial distribution function, respectively. The results showed that two forms of associative adsorption and dissociative adsorption were found on the surface of CaSO4·2H2O and C3A. The internal structure of CaSO4·2H2O was more conducive to the movement of H2O than that of C3A. The diffusibility of overall C3A was weaker than that of overall CaSO4·2H2O due to the cage-like structure of C3A. The sensitivity of the C3A structure was greater than that of CaSO4·2H2O structure to hydrolysis.

Hydrophobic nano-layer on surface prevents H2O adsorption in moderately aluminum deficient Y zeolite crystals

Abstract Experimental and computer simulation sorption and spectroscopic studies were evaluated in-order to be able to answer two puzzling questions. (1) How can a Si/Al ~40 ratio commercial H+ exchanged Y zeolite (H–Y), CBV 780, adsorb only nearly as little H2O as a Si/Al ~ 4330 ratio ZSM-5? (2) Why another Si/Al ~ 40 ratio commercial H–Y, CBV 901, adsorbs much less H2O than CBV 780 and even less than the mentioned highly siliceous ZSM-5? These zeolites have not been chemically treated to be hydrophobic, only their patented synthesis and post-treatment conditions differ. Results indicate that the crystallites of CBV 901 are covered with a defect and aluminum free siliceous nano-layer, which prevents any H2O penetration into the bulk. The external surface of CBV 780 crystallites has about the same little amount of Al as its bulk, presumably less than 4 Al per unit cell. Due to the low number of Al-associated Bronsted acidic hydroxyls (BA-OH), on which H2O preferably adsorbs, little water adsorption takes place in the micropores. On the other hand the surface of the large mesopore defects of CBV 780 must be enriched in with Al to get the measured overall Si/Al ~40 ratio in this material, which provides enough BA-OH sites for adsorbing H2O molecules as a prelude to mesopore filling, that manifests itself in a Type II sorption isotherm.

Building on soft hybrid perovskites: highly oriented metal oxides as electron transport and moisture resistant layers

Poor stability under humid environment is one of the key issues of inorganic–organic hybrid perovskite materials, which limits the transformation of perovskite optoelectronic devices from laboratory to industry. In this paper, a dense ZnO electron transport layer is fabricated directly on top of perovskite films by pulsed laser deposition (PLD) as the first line of defence against the penetration of H2O into perovskite, which shows excellent moisture resistance when compared with conventional organic and oxide nanoparticle counterparts. Smooth, dense and highly oriented crystalline ZnO films are obtained by deposition at near-room-temperature. And importantly, in the meantime, the structure and morphology of underlying perovskite layer are preserved.

Microscopic investigations on the surface-state dependent moisture stability of a hybrid perovskite.

Hybrid organic-inorganic perovskite (HOIP) materials have caught significant attention in photovoltaics and photoelectronics for their outstanding photovoltaic properties. However, their instability to various environment, such as illumination, temperature, moisture and oxygen, hinders their way to commercialization. To figure out the interaction mechanism between H2O and CH3NH3PbI3 (MAPbI3), extensive theoretical studies have been carried out; however, the experimental results are insufficient and inconsistent. Here, we systematically investigate and compare the influence of H2O on MAPbI3 perovskite films with or without DMF) post-annealing in dark or light condition. The interaction between H2O and the surface of pristine MAPbI3 leads to the fusion of grain boundaries thus grain growth into micron level in short-time moisture exposure. While the penetration of H2O into MAPbI3 results in swelled crystalline whisker, cracking into smaller grains in long-time exposure upon the release of H2O. However, no degradation occurs in dark condition. As the DMF post-annealing treatment changes the surface states of MAPbI3, the interactions between the external H2O and internal MAPbI3 significantly varies from the pristine MAPbI3. Three different surface states with different topographies have influence on the interaction process and mechanism with H2O, leading to different decomposition rates, the striped surface that is the most rough among the three and experiencing the minimum change in surface potential with exposure to 80% humidity decomposes into PbI2 fastest. However, the addition of light will once again affect the aforementioned process. It is found that even ambient light could severely speed up the moisture-induced decomposition of MAPbI3, while the N,N-dimethylformamide (DMF) post-annealing treatment significantly improves the stability of MAPbI3 films upon exposure to humidity and illumination, benefiting from the MAI-deficient thus H2O resistant surface.

Pressure tolerance of Artemia cysts compressed in water medium

ABSTRACTThe high pressure tolerance of cysts of Artemia salina was investigated up to several GPa in water. No survival was observed after exposure to 1.0 GPa for 15 min. After exposure to 2.0 GPa for the same time duration, the hatching rate had recovered to 33%, but decreased to 8% following compression at 7.5 GPa. This contrasts with results using Fluorinert™ as the pressure-transmitting medium where 80–88% recovery was observed. The lower survival rate in water is accompanied by swelling of the eggs, indicating that liquid H2O close to the ice-VI crystallization pressure penetrated inside the eggs. This pressure exceeds the stability limit for proteins and other key biomolecules components within the embryos that could not be resuscitated. Rehydration takes several minutes and so was not completed for all samples compressed to higher pressures, prior to ice-VI formation, resulting in renewed survival. However H2O penetration inside the shell resulted in increased mortality.

Computational studies of water and carbon dioxide interactions with cellobiose.

B3LYP/6-311++G** with dispersion correction (DFT-D) was used to study local and global minimum energy structures of water (H2O) or carbon dioxide (CO2) bonding with a pair of cellobiose molecules. The calculations showed that neither the H2O nor the CO2 prefer to be between the cellobiose molecules, and that the minimum energy structures occur when these molecules bond to the outer surface of the cellobiose pair. The calculations also showed that the low energy structures have a larger number of inter-cellobiose hydrogen bonds than the high energy structures. These results indicate that penetration of H2O or CO2 between adjacent cellobiose pairs, which would assist steam or supercritical CO2 (SC-CO2) explosion of cellulose, is not energetically favored. Comparison of the energies obtained with DFT-D and DFT (the same method but without dispersion correction) show that both hydrogen bonds and van der Waals interactions play an important role in cellobiose-cellobiose interactions.

Water-enhanced negative bias temperature instability in p-type low temperature polycrystalline silicon thin film transistors

Water-enhanced degradation of p-type low temperature polycrystalline silicon thin film transistors under negative bias temperature (NBT) condition is studied. H2O penetration into gate oxide network and the role of H2O during NBT stress are confirmed and clarified respectively. To prevent H2O diffusion, a combination of a layer of PECVD SiO2 and a layer of PECVD Si3N4 as passivation layers are investigated, revealing that 100nm SiO2 and 300nm Si3N4 can effectively block H2O diffusion and improve device NBT reliability.

Evaluation of synergistic effect of nanozinc/nanoclay additives on the corrosion performance of zinc-rich polyurethane nanocomposite coatings using electrochemical properties and salt spray testing

This research work focuses on the synthesis, characterization and processing of polyurethane/zinc/clay nanocomposites to improve the corrosion performance of zinc-rich coatings. Therefore different percentages of montmorillonite clay nanolayers were added to zinc-rich polyurethane nanocomposites. Ultrasonication process was used to prepare polyurethane/nanozinc/nanoclay composites. Then coatings were applied on steel panels with composition of 10wt.% nanozinc and 0.5wt.%, 1wt.%, 1.5wt.%, and 2wt.% nanoclay. TEM was used to analyze the structural characteristics of the samples. The results of the structure analysis revealed the size of nanomaterials. The anticorrosive properties of the nanocomposites were investigated using DC polarization technique, electrochemical impedance spectroscopy (EIS), water absorption and salt spray test. The results of electrochemical tests showed that addition of clay nanolayers improves the corrosion resistance of coatings and the best corrosion performance obtained for the nanocomposite sample with 2wt.% nanoclay. Also, according to the results of the salt spray test, the sample with 2wt.% nanoclay showed the least H2O penetration and exfoliation adjacent to the scratches.

Analysis of synergistic effect of nanozinc/nanoclay additives on the corrosion performance of zinc‐rich polyurethane nanocomposite coatings

AbstractThe aim of this study was to analyze the synergistic effect of clay and zinc nanopigments. Therefore different percentages of Montmorillonite clay nanolayers were added to zinc‐rich polyurethane nanocomposites. Ultrasonication process was used to prepare polyurethane/nanozinc/nanoclay nanocomposites. Then coatings were applied on steel panels with composition of 10 wt% nanozinc and 0.5, 1, 1.5, and 2 wt% nanoclay. TEM and XRD were used to analyze the structural characteristics of the nanocomposites. The results of the structure analysis revealed the size of nanomaterials and confirmed the appropriate dispersion in polymer matrix. The anticorrosive properties of the nanocomposites were investigated using salt fog test and electrochemical impedance spectroscopy (EIS). The results of EIS showed that addition of clay nanolayers improves the corrosion resistance of coatings and the best corrosion performance obtained for the nanocomposite sample with 2 wt% nanoclay. Also, according to the results of the salt spray test, the sample with 2 wt% nanoclay showed the least H2O penetration and exfoliation adjacent to the scratches. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers

Effects of Mg, Ca, and Fe(II) Doping on the Kaolinite (001) Surface with H2O Adsorption

AbstractKaolinite is often a cause of deformation in soft-rock tunnel engineering, leading to safety problems. The mechanism of the deformation is closely related to the interaction between kaolinite and water molecules. Because kaolinite has multiple defects, the effects of Mg, Ca, and Fe(II) doping on the atomic structure of the kaolinite (001) surface, and the subsequent adsorption and penetration of H2O into the interlayer, were studied systematically using density-functional theory. The results showed that for the Mg-, Ca-, and Fe(II)-doped kaolinites (001), the surface relaxation around the doping layer changed from contraction to expansion, due to the redistribution of electrons. The adsorption energies of the H2O monomer on Mg-, Ca-, and Fe(II)-doped kaolinites (001) were less than on undoped kaolinite (001). The results further revealed that the H2O molecule can also adsorb on the hollow site on the second-layer O surface of the Mg-, Ca-, and Fe(II)-doped kaolinites (001). For the undoped kaolinite, however, the H2O molecule adsorbs on the surface only. The energetic barriers for penetration of H2O from the adsorption site on the surface to the adsorption site on the O surface of Mg-, Ca-, and Fe(II)-doped kaolinites were also calculated: 1.18 eV, 1.07 eV, and 1.41 eV, respectively. The results imply that the influences of Mg, Ca, and Fe(II) doping on kaolinite allow the adsorbed water molecules to penetrate from the on-surface adsorption site to the O-surface site.

Chemical and electrical stabilities of organic thin-film transistors for display application

— The chemical and electrical stabilities of pentacene organic thin-film transistors (OTFTs) fabricated on plastic by a self-organized process was studied. The degradation in on-current, threshold voltage, and field-effect mobility of the OTFT under air exposure can be expressed in exponential form in time and can be reduced by using multilayer passivation on the organic semiconductor, which reduces the penetration of H2O and O2 into the pentacene. The threshold voltage degrades during negative gate bias stress, which can be reduced significantly by optimizing the organic gate insulator used for the OTFT. A stable OTFT can be fabricated by using the proper organic gate insulator.

Conformational Change Restricted Selectivity in the Surface Sulfonation of Polypropylene with Sulfuric Acid

Surface sulfonation of solid polypropylene (PP) with hot concentrated H2SO4 has been studied by diffuse reflectance Fourier-transformed infrared (DRIFT) and X-ray photoelectron (XP) spectroscopies. Both measurements indicated that the sulfonation of PP followed by slight oxidation and the formation of CC bonds is enhanced with both increasing reaction temperature and time. The time dependence of H2O penetration into sulfonated PP mesh sheets was analyzed using a rearranged Washburn's equation, providing a quantitative indicator of surface hydrophilicity. A positive linear correlation was obtained between the hydrophilicity and the degree of sulfonation. The charge distribution calculated for models of SO3 and PP molecules by the PM3 molecular orbital (MO) method suggested that the sulfonation of PP proceeds via electrophilic addition of SO3. It was further predicted from the MO calculations for models of sulfonated PP molecules that side CH3 groups are more susceptible to sulfonation than C atoms of the main chain due to a drastic conformational change of the main chain in the latter case. The heat of reaction in each pathway (ΔE) was estimated to be ΔE(side CH3 groups) = −63.5 kJ (unit mol)-1, ΔE(C(CH3)SO3H) = −56.8 kJ (unit mol)-1, and ΔE(CH(SO3H)) = −55.8 kJ (unit mol)-1, respectively. The selectivity in the sulfonation of PP termed “the conformational change restricted selectivity (CCRS)” was shown to increase with a decrease in the reaction temperature by analyzing the DRIFT signals around 600 cm-1 assigned to the deformation of S−O bonds and the stretching vibration of S−C bonds.

The Effect of Immersion in a Buffered Base on the Optical Properties and Microhardness of Fluorozirconate Glasses

Two ZrF4—BaF2—LaF3—AIF3 (ZBLA) and four ZrF4—BaF2—YF3—AIF3 (ZBYA) glasses were immersed in a buffered base at 25°C for several days. They were then examined using an IR spectrophotometer in order to determine the effect on the optical properties, and a microhardness tester for surface degradation. The ZrF4 content in these compositions ranged from 44 mol% to 57 mol%. IR analysis showed that the amount of hydroxyl and H2O penetration was dependent upon the concentration of ZrF4 in the glass. The IR characteristics of ZBYA—1, which contained 44 mol% ZrF4, did not appear to be affected by the aqueous environment, while ZBLA—20, which contained 57 mol% ZrF4, showed the presence of a large amount of hydroxyl and H2O. The base immersion did not appear to strongly affect the microhardness of the compositions.

Short-term water stress leads to a stimulation of sucrose synthesis by activating sucrose-phosphate synthase

The aim of this work was to identify which aspects of photosynthetic metabolism respond most sensitively to leaf water deficit. Spinach (Spinacia oleracea L.) leaf discs were floated on sorbitol concentrations of increasing molarity and changes of the protoplast volume were estimated using [(14)C]sorbitol and (3)H2O penetration. Detached leaves were also wilted until 10% of their fresh weight was lost. Photosynthesis was studied at very high external CO2 concentrations, to eliminate the effect of closing stomata. There was no large inhibition of CO2 fixation after wilting leaves, or until the external water deficit was greater than-1.2 MPa. However, partitioning changed markedly at these moderate water deficits: more sucrose and less starch was made. When an inhibition of CO2-saturated photosynthesis did appear at a water deficit of-2.0 MPa and above, measurements of chlorophyll-fluorescence quenching and metabolite levels showed the thylakoid reactions were not especially susceptible to short-term water stress. The inhibition was accompanied by a small increase of the triose phosphate: ribulose-1,5-bisphosphate ratio, showing regeneration of ribulose-1,5-bisphosphate was affected. However, there was also a general increase of the estimated concentrations of most metabolites, indicating that there is no specific site for the inhibition of photosynthesis. Increasing water deficit led to a large increase of fructose-2,6-bisphosphate. This is explained in terms of a simultaneous increase of fructose-6-phosphate and inorganic phosphate as the cell shrinks. The high fructose-2,6-bisphosphate led to the accumulation of triose phosphates, and the potential significance of this for protection against photoinhibition is discussed. There was an increase in the extractable activity of sucrose-phosphate synthase. This was only detected when the enzyme was assayed in conditions which distinguish between different kinetic forms which have previously been identified in spinach leaves. It is proposed that activation of sucrose-phosphate synthase is one of the first sites at which spinach leaves respond to a rising water deficit. This could be of importance for osmoregulation.