Presence Of NaCl Solution Research Articles

Interfacial Degradation of Calcium Silicate Hydrate and Epoxy under a Hygrothermal Environment: An Experimental and Molecular Model Study

The adhesion at the concrete/epoxy interface is crucial to the reinforcement of carbon fiber-reinforced polymer (CFRP) sheets. The multiscale mechanism of adhesion, particularly under a hygrothermal environment, yet remains largely unclear. This paper combines molecular dynamics (MD) and synthesis experiments of a novel single-phase calcium silicate hydrate (C-S-H) and epoxy composite to investigate the combined effects of aggressive chemicals and temperature on the bonding properties. MD models were constructed under various conditions on C-S-H/epoxy composites, whose equilibrium configuration, dynamic property, bond connection, interfacial interaction energy, and mechanical properties were quantified. In addition, the experiments were carried out under different temperatures and humidity conditions to explore the macroscopic splitting tensile property of the composites and further validate the MD results. The MD results suggest that the Ca ions on the C-S-H surface are crucial to the adhesion by forming Ca–O and Ca–N bonds with epoxy. However, these bonds were reduced in the presence of water molecules, with a reduction also of the interfacial energy. The degradation effects are exacerbated by the presence of NaCl solution, as Na ions gather around the interfacial region of C-S-H/epoxy, further accumulating water molecules by forming hydrated ion clusters. This process is accelerated by elevated temperature. The experiment results suggest that without the influence of NaCl solution, a moist C-S-H surface turns to gain a stronger bonding with epoxy when the curing temperature is higher (40, 60 °C). Meanwhile, the bonding properties of a dry C-S-H surface and epoxy are less sensitive to temperature. This work provides new insight into understanding the bonding mechanism on the C-S-H/epoxy interface and may benefit the engineering application of CFRP-concrete reinforcement.

Interaction of Heparin with Proteins: Hydration Effects.

We present a thermodynamic investigation of the interaction of heparin with lysozyme in the presence of potassium glutamate (KGlu). The binding constant Kb is measured by isothermal titration calorimetry (ITC) in a temperature range from 288 to 310 K for concentrations of KGlu between 25 and 175 mM. The free energy of binding ΔGb derived from Kb is strongly decreasing with increasing concentration of KGlu, whereas the dependence of ΔGb on temperature T is found to be small. The decrease of ΔGb can be explained in terms of counterion release: Binding of lysozyme to the strong polyelectrolyte heparin liberates approximately three of the condensed counterions of heparin, thus increasing the entropy of the system. The dependence of ΔGb on T, on the other hand, is traced back to a change of hydration of the protein and the polyelectrolyte upon complex formation. This dependence is quantitatively described by the parameter Δw that depends on T and vanishes at a characteristic temperature T0. A comparison of the complex formation in the presence of KGlu with the one in the presence of NaCl demonstrates that the parameters related to hydration are changed considerably. The characteristic temperature T0 in the presence of KGlu solutions is considerably smaller than that in the presence of NaCl solutions. The change of specific heat Δcp is found to become more negative with increasing salt concentration: This finding agrees with the model-free analysis by the generalized van't Hoff equation. The entire analysis reveals a small but important change of the free energy of binding by hydration. It shows that these ion-specific Hofmeister effects can be modeled quantitatively in terms of a characteristic temperature T0 and a parameter describing the dependence of Δcp on salt concentration.

Influence of heat treatment on the mechanical and the lubricant wear characteristics of stainless-steel grades against 5 wt% NaCl as industrial shielding materials

This article investigates the impact of the heat treatment, and lubricant wear measurements at 5 wt % NaCl solution, mechanical and radiation shielding properties of three grades of stainless steels: SS316, M303, and SS201. The obtained results showed that heat-treated martensitic stainless-steel grade has improved mechanical and tribological properties while heat-treated austenitic stainless-steel grades showed deteriorated wear resistance. The radiation shielding parameters of the studied grades are comparable. The effectiveness of heat treatment in the presence of NaCl solution is verified.

Influence of wetting fluids on the compressive strength, physicochemical, and pore-structure evolution in lime-treated silty soil subjected to wetting and drying cycles

The long-term benefit brought in lime-treated soil can be altered by the nature of the surrounding wetting fluid, thus, affecting its durability. However, studies regarding such impact are limited. In this study, the influence of different wetting fluids on the microstructural, physicochemical modifications, and Unconfined Compressive Strength (UCS) evolution of lime-treated soil is investigated. Lime-treated soils are subjected to wetting and drying cycles using 0.10 M and 0.60 M NaCl solutions, demineralized water, and Methyl Methacrylate. The results show that despite the soil being exposed to several wetting and drying cycles, the UCS evolved positively compared to the reference specimen. However, this evolution varies with the types of wetting fluids the specimens are exposed to. The NaCls-and Methyl Methacrylate-subjected soils showed an increase in UCS up to about 3 times, while the UCS increase is about 2 times in the corresponding demineralized water subjected soil. Similarly, the extent of the variation of the final pH and the cumulative calcium concentrations measured in the effluent is marked by the wetting fluids available in the surrounding medium. At the pore structure level, the presence of NaCl solutions and Methyl Methacrylate solvent as a wetting fluid was observed to enhance the evolution of pores smaller than 3000 Å. However, such a phenomenon is less significant in the demineralized water-subjected soil. Thus, the study confirms that the type of wetting fluid plays an important role in the evolution of lime-treated soil during the wetting and drying cycles.

Preparation and Characterizations of PSS/PDADMAC Polyelectrolyte Complex Hydrogel.

Polyelectrolyte complex (PEC) hydrogel, formed via physically electrostatic crosslinks between polyanion and polycation, is an interesting hydrogel in terms of its nontoxicity and solvent-free technique. In this work, poly (sodium 4-styrenesulfonate) (PSS)/poly (diallyl dimethyl ammonium chloride) (PDADMAC) complex hydrogels were prepared. Firstly, the PSS/PDADMAC complex aggregates using various PSS/PDADMAC mole fractions that were prepared in the presence of NaCl solution. Then, the aggregates were resolubilized under stirring at 70 °C for 2 h to obtain a homogeneous PEC solution. Finally, the PEC solution was dialyzed using a dialysis membrane with 3500 molecular cut-off for 1 day. The dialysis bath was changed every interval period of 2 h to control the rate of reversible electrostatic interaction, resulting in the homogenous PEC hydrogel with porous morphology as revealed by SEM and BET investigations. The dimensional stability and viscoelasticity of the PEC hydrogel was studied by DMA experiment, which showed the viscoelastic behavior at a compressive force ranging from 0 to 0.1 N. Finally, PSS/PDADMAC hydrogels showed a high water absorbency property and excellent affinity to textile anionic dyes.

Effects of Cations on HPTS Fluorescence and Quantification of Free Gadolinium Ions in Solution; Assessment of Intracellular Release of Gd3+ from Gd-Based MRI Contrast Agents.

8-Hydroxypyrene-1,3,6-trisulfonate (HPTS) is a small, hydrophilic fluorescent molecule. Since the pKa of the hydroxyl group is close to neutrality and quickly responds to pH changes, it is widely used as a pH-reporter in cell biology for measurements of intracellular pH. HPTS fluorescence (both excitation and emission spectra) at variable pH was measured in pure water in the presence of NaCl solution or in the presence of different buffers (PBS or hepes in the presence or not of NaCl) and in a solution containing BSA. pKa values have been obtained from the sigmoidal curves. Herein, we investigated the effect of mono-, di-, and trivalent cations (Na+, Ca2+, La3+, Gd3+) on fluorescence changes and proposed its use for the quantification of trivalent cations (e.g., gadolinium ions) present in solution as acqua-ions. Starting from the linear regression, the LoD value of 6.32 µM for the Gd3+ detection was calculated. The effects on the emission were also analyzed in the presence of a combination of Gd3+ at two different concentrations and the previously indicated mono and di-valent ions. The study demonstrated the feasibility of a qualitative method to investigate the intracellular Gd3+ release upon the administration of Gd-based contrast agents in murine macrophages.

Synergistic Interaction and Binding Efficiency of Tetracaine Hydrochloride (Anesthetic Drug) with Anionic Surfactants in the Presence of NaCl Solution Using Surface Tension and UV-Visible Spectroscopic Methods.

Surfactants are ubiquitous materials that are used in diverse formulations of various products. For instance, they improve the formulation of gel by improving its wetting and rheological properties. Here, we describe the effects of anionic surfactants on an anesthetic drug, tetracaine hydrochloride (TCH), in NaCl solution with tensiometry and UV–visible techniques. Various micellar, interfacial, and thermodynamic parameters were estimated. The outputs were examined by using different theoretical models to attain a profound knowledge of drug–surfactant mixtures. The presence of attractive interactions among drug and surfactant monomers (synergism) in mixed micelle was inferred. However, it was found that sodium dodecyl sulfate (SDS) showed greater interactions with the drug in comparison to sodium lauryl sarcosine (SLS). The binding of the drug with surfactants was monitored with a spectroscopic technique (UV–visible spectra). The results of this study could help optimize the compositions of these mixed aggregates and find the synergism between monomers of different used amphiphiles.

Compressive strength reduction of cement pastes exposed to sodium chloride solutions: Secondary ettringite formation

Interactions of sodium chloride (NaCl) with cement hydrates can cause chemical and physical changes in cement pastes, leading to premature deterioration, particularly in cold climates. The present study explores the conditions responsible for the damage and investigates potential chemical changes in cement paste exposed to different concentrations of NaCl solutions (0 to 4 M) at temperatures of 25 °C and 5 °C. Thermogravimetric analysis (TGA) was used to investigate the effect of salt concentrations on the leaching of calcium hydroxide (CH) and Friedel’s salts (FS) formation. X-ray diffraction (XRD) was used to study phase transformations and final phase products associated with the chemical changes. Thermodynamic modeling was performed to predict changes in the hydrated phase assemblage and corresponding volumetric changes due to NaCl ingress. A noticeable reduction in the compressive strength was observed with the increase in NaCl concentrations at 5 °C compared to 25 °C. It was found that temperature plays a vital role in reducing the compressive strength in the presence of NaCl. Leaching of CH was not observed, indicating the stability of the CH phase in the presence of NaCl solution. The FS formation was found to increase as salt concentrations increase up to a point (2 M NaCl) where it started to plateau at higher salt concentrations. Observations from XRD revealed that the secondary ettringite formation is the final phase product of chemical changes that occurred in cement paste exposed to high NaCl concentration and lower temperature. Since the TGA confirmed the stability of FS and CH phases at high NaCl concentrations, the reduction in the compressive strength appeared to be mainly due to secondary ettringite formation. Results from thermodynamic calculations were in excellent agreement with the experimental results, indicating that the damage may be attributed to expansions associated with the secondary ettringite formation.

Effects of Salinity on Hydrate Phase Equilibrium and Kinetics of SF6, HFC134a, and Their Mixture

In this study, the effects of salinity on the equilibrium and kinetics of sulfur hexafluoride (SF6), 1,1,1,2-tetrafluoroethane (HFC134a), and their mixture were evaluated to analyze their potential applications to hydrate-based desalination. The equilibrium pressure of the mixture gas (SF6/HFC134a) was lower than that of pure SF6 gas but higher than that of pure HFC134a gas. The thermodynamic effects of various concentrations (0, 3.5, 5, and 8 wt %) of NaCl on the gas hydrates were evaluated. Experiments were performed on the formation kinetics in the presence of NaCl solution at the same experimental temperature and pressure (274.15 K and 0.70 MPa). The hydrate growth rates decreased with increasing NaCl concentration. The rates also declined with time, associated with the inhibition of mass transfer between the gas and the liquid. During hydrate formation, the vapor compositions of the mixture gas were analyzed by in situ Raman spectroscopy and the results were consistent with those obtained by gas chromatography. Furthermore, an in situ Raman spectroscopic analysis demonstrated that the SF6 and HFC134a molecules occupy only the large cage (51264) of the structure II (sII) hydrate during SF6/HFC134a formation and the addition of salt did not change the structure of the SF6 and HFC134a hydrates. The hydrate phase behavior and kinetic results of this study can serve as foundational data for hydrate-based desalination technology and fluorinated gases separation and recovery processes.

Interaction of borohydride stabilized silver nanoparticles with sulfur-containing organophosphates.

Understanding the interactions between nanoparticles and organophosphates is the key to developing cost-effective colorimetric pesticide detection. We have studied the interaction between three different organophosphates containing the P Created by potrace 1.16, written by Peter Selinger 2001-2019 ]]> S group and borohydride stabilized silver nanoparticles. Three different organophosphates, namely phorate, chlorpyrifos, and malathion, have been used. The colorimetric changes are corroborated with UV-visible absorption studies along with the change in particle size and zeta potential. This effect persists in the presence of NaCl solution also. The chlorpyrifos and malathion do not show significant interactions with uncapped nanoparticles over time, while phorate undergoes degradation due to the scission of the S–CH2 linkage. A reaction mechanism, wherein a silver and sulfur (Ag→S) complex is formed, which is in agreement with Raman spectroscopic studies is proposed. The orientations of phorate near Ag nanoparticles are discussed from the adsorption energy calculation using density functional theory.

Cementitious materials exposed to high concentration of sodium chloride solution: Formation of a deleterious chemical phase change

This paper investigates deleterious chemical interactions between cementitious materials and high concentrations of sodium chloride (NaCl) solution (i.e., salt concentration >12% by mass). The behavior of mortar specimens made using Type I and Type V ordinary portland cements was investigated as the temperature varied in the presence of NaCl solution with concentrations of 15% and 20% (by mass). A low-temperature longitudinal guarded comparative calorimeter (LGCC) in conjunction with an acousto-ultrasonic technique were used to monitor the damage development in mortar samples. Cooling-heating cycles were applied with a minimum temperature above the freezing temperature of the solution to avoid ice formation. Nevertheless, damage was observed in specimens. Calcium aluminate phases, mainly tricalcium aluminate (C3A), seem to be the source of damage as the magnitude of damage was relatively minor when Type V cement (C3A < 5% by mass) was used. To further investigate the source of the damage, a low-temperature differential scanning calorimeter (LT-DSC) was used to study chemical phase transitions during temperature change in three types of powder specimens exposed to different concetrations of NaCl solution: (1) hydrated cement pastes, made using Type I and Type V cements, (2) cement pure phases, consisting of C3A and gypsum, and (3) cement hydration products, consisting of calcium hydroxide (CH) and calcium sulfoaluminate phases (monosulfate (AFm) and ettringite (AFt)). A formation of a chemical phase at a temperature range between 0 °C and 10 °C was observed that may be the source of damage in cementitious materials exposed to high concentration of NaCl solutions. It was found that the interaction of high concentrations of NaCl solution with C3A and calcium sulfoaluminate phases in the cementitious system are the origin of the chemical phase formation.

Numerical simulation of salt transport and crystallization in drying Prague sandstone using an experimentally consistent multiphase model

Drying of porous media in the presence of salt is a very common phenomenon with many applications but it is not totally understood so far. Some experiments that recently appeared in the literature have shown that the kinetics of drying not only strongly depends upon the quantity of precipitated salt but also upon the form in which the salt precipitates. In this paper, a coupled multiphase model that is capable of describing the different drying kinetics taking into account the different efflorescence formations is presented. The model is then validated through two different experimental campaigns on drying in presence of NaCl solution.

Small interfering RNA delivery into the liver by cationic cholesterol derivative-based liposomes

Purpose: Previously, we reported that the cationic liposomes composed of a cationic cholesterol derivative, cholesteryl (2-((2-hydroxyethyl)amino)ethyl)carbamate (OH-C-Chol) and 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) (termed LP-C), could deliver small interfering RNAs (siRNAs) with high transfection efficiency into tumor cells. In this study, to develop a liposomal vector for siRNA delivery in vivo, we prepared the poly(ethyleneglycol) (PEG)-modified cationic liposomes (LP-C-PEG) and evaluated their transfection efficiency in vitro and in vivo.Materials and methods: We prepared LP-C-PEG/siRNA complexes (LP-C-PEG lipoplexes) formed in water or 50 mM NaCl solution, and evaluated their siRNA biodistribution and gene silencing effect in mice after intravenous injection.Results: LP-C-PEG lipoplexes strongly exhibited in vitro gene silencing effects in human breast tumor MCF-7 cells as well as LP-C lipoplexes. In particular, formation of LP-C and LP-C-PEG lipoplexes in the NaCl solution increased the cellular association. When LP-C-PEG lipoplexes with Cy5.5-labeled siRNA formed in water or NaCl solution were injected into mice, accumulation of the siRNA was observed in the liver. Furthermore, injection of LP-C-PEG lipoplexes with ApoB siRNA could suppress ApoB mRNA levels in the liver and reduce very-low-density lipoprotein/low-density lipoprotein levels in serum compared with that after Cont siRNA transfection, although the presence of NaCl solution in forming the lipoplexes did not affect gene silencing effects in vivo.Conclusions: LP-C-PEG may have potential as a gene vector for siRNA delivery to the liver.

Label-free, sensitivity detection of fibrillar fibrin using gold nanoparticle-based chemiluminescence system.

A novel, label-free, gold nanoparticles (AuNPs)-based chemiluminescence assay has been developed for the detection of fibrillar fibrin. The method relied on the interaction of fibrinogen (Fib) with AuNPs and the aggregated AuNPs induce a strong luminol-H2O2 chemiluminesecence (CL) signal. We prepared the 12-nm-diameter AuNPs which well dispersed in the solution. Fib was absorbed on the surface of AuNPs against the aggregation of AuNPs in 1.0M NaCl. Otherwise, Fib was catalyzed to form fibrillar fibrin in the presence of thrombin. The fibrin induced AuNPs aggregated in the presence of NaCl solution. The catalytic activity of aggregated AuNPs on the luminol-H2O2 CL reaction is greatly enhanced. This allows us to utilize the luminol-H2O2 CL system for quantitative analysis of thrombin, which was used to denote fibrosis degree of Fib. The assay showed a linear toward fibrillar fibrin concentration in the range of 2.7 × 10(-15)-2.7 × 10(-13)M with a correlation of 0.9920. The limit of detection for fibrin was experimentally determined to be 1 fM, based on a signal-to-noise ratio (S/N) of 3. Relative to conventional methods, this method offers the advantages of higher sensitivity and selectivity and lower cost, showing great potential for medical diagnosis.

Equilibrium, Kinetics, and Spectroscopic Studies of SF6 Hydrate in NaCl Electrolyte Solution.

Many studies have focused on desalination via hydrate formation; however, for their potential application, knowledge pertaining to thermodynamic stability, formation kinetics, and guest occupation behavior in clathrate hydrates needs to be determined. Herein, the phase equilibria of SF6 hydrates in the presence of NaCl solutions (0, 2, 4, and 10 wt %) were monitored in the temperature range of 277-286 K and under pressures of up to 1.4 MPa. The formation kinetics of SF6 hydrates in the presence of NaCl solutions (0, 2, and 4 wt %) was also investigated. Gas consumption curves of SF6 hydrates showed that a pure SF6 hydrate system allowed fast hydrate growth as well as high conversion yield, whereas SF6 hydrate in the presence of NaCl solutions showed retarded hydrate growth rate as well as low conversion yield. In addition, structural identification of SF6 hydrates with and without NaCl solutions was performed using spectroscopic tools such as Raman spectroscopy and X-ray diffraction. The Raman spectrometer was also used to evaluate the temperature-dependent release behavior of guest molecules in SF6 and SF6 + 4 wt % NaCl hydrates. The results indicate that whereas SF6 hydrate starts to decompose at around 240 K, the escape of SF6 molecules in SF6 + 4 wt % NaCl hydrate is initiated rapidly at around 205 K. The results of this study can provide a better understanding of guest-host interaction in electrolyte-containing systems.

Photocatalytic properties of exposed crystal surface-controlled rutile TiO2 nanorod assembled microspheres

The photocatalytic activity of TiO2 is correlated with its exposed crystal surface, phase composition, morphology, and crystallite size. In this study, TiO2 microspheres with exposed crystal surface-controlled rutile TiO2 nanorods were fabricated by employing a simple hydrothermal reaction in the presence of NaCl solution. The crystal phase, morphology, and size of the as-obtained materials were significantly dependent on the NaCl concentration. The exposed crystal surface of TiO2 nanorods could be tailored by adjusting the NaCl concentration. With increasing NaCl concentration, the exposed area of the (111) crystal surface gradually decreased, whereas the area of the newly exposed (001) surface gradually increased. Characterization results indicated that the crystal phase of the TiO2 microspheres was the only rutile structure in the system and no brookite phase was found. The diameter of the microspheres can be changed from 3.5μm to 2μm by tuning the NaCl concentration. Photocatalytic degradation of papermaking wastewater using the synthesized materials showed that the photocatalytic activities of the samples are affected by the exposed (001) crystal surface of TiO2, which can induce the separation of electrons and holes, thereby resulting in improved photocatalytic activity.

Morphologically-tunable TiO2 nanorod film with high energy facets: green synthesis, growth mechanism and photocatalytic activity

A novel green synthesis strategy was developed to synthesize a film photocatalyst containing anatase TiO(2) nanorods wholly dominated with {100} and {101} facets by employing a simple hydrothermal reaction in the presence of NaCl solution and hydrogen titanate nanosheet array film. The formation mechanism of the anatase TiO(2) nanorods was deduced from X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) characterizations, which revealed that the highly reactive {100} facets were derived from the enhanced structural stability of hydrogen titanate induced by Na(+) and selective adsorption of Cl(-) on the {100} facets of anatase TiO(2) crystals. Photocatalytic performance has indicated that the TiO(2) nanorods with {100} facet exposure exhibit much higher activities than that of rhombic nanoparticles with {101} facet exposure for the degradation of organic contaminants, which may be primarily ascribed to the high surface energy of {100} facets.

Shape-controllable synthesis of dendritic silver nanostructures at room temperature

In this communication, we demonstrated a simple chemical approach for preparing dendritic silver nanostructures by mixing AgNO3 aqueous and o-phenylenediamine in the presence of NaCl solutions at room temperature. o-Phenylenediamine was found to act as a stabilizer as well as a reduction agent. Asformed silver dendrites were examined by scanning electron microscopy, energy dispersive spectrometry, X-ray diffraction, and Fourier transform infrared spectroscopy techniques. We found that the concentration of NaCl strongly influenced the shape of silver structures. The forming AgCl serve as efficient etchant and also produces single-crystal seeds. The possible formation mechanism is also discussed.

Influence of Fly Ash From Co-Combustion of Coal and Biomass on Scaling Resistance of Concrete / Wpływ Popiołu Lotnego Ze Współspalania Wegla I Biomasy Na Odpornosc Betonu Na Powierzchniowe Łuszczenie

Abstract Industrial utilization of fly ash from various kinds of fuel plays an important role in the environmentally clean and cost effective power production. The primary market for fly ash utilization is as a pozzolanic addition in concrete production. The paper concerns the concretes containing fly ash called Fly Ash from Biomass (FAB) from co-combustion of hard coal and wood biomass (wood chips). Characterization of the fly ash was carried on by means of X-ray diffractometry and E-SEM/EDS analysis. The results of laboratory studies undertaken to evaluate the influence of FAB on concrete resistance to surface scaling due to cyclic freezing and thawing in the presence of NaCl solution were presented. The tests were carried out for concretes containing up to 25% of fly ash related to cement mass. Additionally, the microstructure of air-voids was described. It was concluded that the FAB has significant effect on concrete freeze/thaw durability. The replacement of cement by fly ash from co-combustion progressively transformed the concrete microstructure into less resistant against freeze/thaw cycles and excessive dosage (over 15%) may dangerously increase the scaling.

Solution growth of nano- to microscopic ZnO on Zn

Abstract A new strategy has been successfully designed for the first time to synthesize ZnO nanorod arrays on a zinc surface by employing a novel NaCl solution corrosion-based approach. The natural oxidation of zinc metal by naturally dissolved oxygen in water is very slow due to the surface oxide layer. However, in the presence of NaCl solution, this spontaneous oxidation reaction can be accelerated drastically, and thus ZnO nanorod arrays can readily grow along the [0 0 1] direction on the surface of the zinc foil. In particular, this simple synthetic strategy only requires NaCl solution and zinc foil, which enables us to generate, at large scale, low cost, and moderate temperature, advanced thin films. Photoluminescence (PL) spectrum reveals that our obtained ZnO nanorods have negligible oxygen vacancies. By the way, a two-dimensional pattern of flower-like ZnO nanosheets on Zn by formamide-induced sequential nucleation and growth on zinc foil substrate has also been demonstrated.