Addition Of Surfactant Research Articles

COMMERCIAL POLYURETHANE CLEAR COAT REINFORCED WITH CARBON NANOTUBES AND HYDROXYAPATITE POWDERS

Advanced anticorrosive coatings are used in practical applications across various industries, including electronics, biomaterials, automotive and aerospace sectors. Among ceramics, hydroxyapatite (HA) stands out due to its high corrosion resistance and chemical stability. In this study, HA powders were synthesized via the hydrothermal method using calcium nitrate (Ca(NO3)2•4H2O) and di-ammonium hydrogen phosphate ((NH4)2HPO4), with the addition of surfactants to modulate their morphology. X-ray diffraction analysis confirmed the hexagonal phase of HA with a crystallite size of approximately 20 nm. Scanning electron microscopy (SEM) revealed a nanorod morphology with varying lengths. The HA powders were then blended with multi-walled carbon nanotubes (MWCNTs) poured into a commercial polyurethane clear coat to develop an advanced anticorrosive coating. This composite coating, containing varying loadings of MWCNTs and HA powders, was applied to commercial low-carbon steel (ASTM A1008). Image segmentation analysis quantified the oxide percentage on the coated surfaces. Notably, HA nanorods synthesized using cetyltrimethylammonium bromide (CTAB) as a surfactant and combined with MWCNTs at concentrations of 20 mg HA and 1 mg MWCNTs effectively reduced the oxidation percentage from 28.76% to 4.01%.

Affinity of Malassezia and Other Yeasts for Pulmonary Lipids

Pulmonary surfactant, the primary substance lining the epithelium of the human Lower Respiratory Tract (LRT), is rich in lipids, with dipalmitoyl-phosphatidylcholine (DPPC) being the most abundant. Although surfactants are known to have antifungal activity against some yeast species, the significant presence of species like Malassezia restricta in the lung mycobiome suggests that these yeasts may exhibit some level of lipo-tolerance or even lipo-affinity for pulmonary lipids. This study explored the affinity and tolerance of yeasts, identified as significant members of the lung microbiome, to pulmonary lipids through culture-based methods. Eleven species from the genera Malassezia, Candida (including the new genera Nakaseomyces and Meyerozyma), and Cryptococcus were tested for their growth on media containing pulmonary lipids such as DPPC and commercial porcine surfactant and in other culture medium that contain non-pulmonary lipids such as glycerol monostearate and tweens. The yeasts’ lipo-affinity or lipo-tolerance was assessed based on their growth on these lipids compared to standard media, specifically Modified Leeming Notman Agar (MLNA) for Malassezia species and Sabouraud Dextrose Agar (SDA) for the other genera. The addition of DPPC or surfactant to the media enhanced the growth of most Malassezia yeasts and some Cryptococcus species. C. parapsilosis, Meyerozyma guilliermondii and Cryptococcus neoformans s.s. showed similar growth to that on the standard media, while the other yeasts primarily demonstrated lipo-tolerance without lipo-affinity for these compounds. To our knowledge, this is the first report on the influence of pulmonary lipids on the in vitro growth of Malassezia spp. and other yeast members of the lung mycobiome. Some yeasts, such as Malassezia restricta, commonly found in the lower respiratory tract (LRT), exhibit specific affinity for lung lipids like DPPC and commercial porcine surfactant. This finding suggests that lung lipids may play a significant role in shaping the LRT mycobiome.

Enhancing Thermal Conductivity of Water-Ethylene Glycol Mixtures: A Study on TiO2-Al2O3 Hybrid Nanofluids with Surfactants

This analysis examines the thermal behaviour of 40% ethylene glycol-based TiO2-Al2O3 hybrid nanofluids by synthesizing them and assessing their thermal conductivity as a function of volume concentration and temperature. These hybrid nanofluids, emerging as a promising new class of advanced operating fluids, offer remarkable potential for enhancing heat transfer performance in various thermal engineering applications. Using a two-stage synthesis method, TiO2-Al2O3/40% ethylene glycol nanofluids were prepared across five distinct volume focuses (varying from 0.02% to 0.1%), incorporating Polyvinylpyrrolidone (PVP) as a stabilizing emulsifier. Precise thermal conductivity measurements were conducted over 30 °C to 80 °C, with incremental steps of 10 °C, ensuring comprehensive data collection. The investigation yielded significant findings, notably a substantial maximum thermal conductivity enhancement of 37.44%, observed at 80 °C with a 0.1% volume concentration, demonstrating pronounced sensitivity to elevated temperatures and concentrations. The strategic addition of PVP surfactant resulted in a remarkable 125% improvement in the nanofluid's stability period, although a maximum 5.33% reduction in thermal conductivity. Considering the inadequacy of existing predictive models to capture the observed data accurately, this study proposed developing a high-precision predictive model, achieving an impressive maximum deviation of less than 3%. The research concludes that these hybrid nanofluids, characterized by their exceptional stability and significantly enhanced thermal conductivity, hold immense potential to revolutionize heat transfer applications across various domains of practical thermal engineering. This breakthrough paves the way for developing more efficient, high-performance heat transfer systems, potentially catalysing energy efficiency and thermal management advancements across diverse industrial sectors.

Fabrication of stable hydrogel microspheres with hydrophobic shell using water-in-water (W/W) Pickering emulsion template

Hydrogel microspheres are promising for food applications. The water-in-oil (W/O) emulsion template is commonly used to prepare the hydrogel microspheres. However, this method often involves synthetic surfactants and toxic organic solvents to remove the oil phase. The swelling problem of the resultant microspheres is another obstacle. In this study the water-in-water (W/W) emulsion template of gelatin-in-dextran was used to prepare the hydrogel microspheres, without the addition of surfactants, toxic reagents and high energy input. To prevent swelling, zein particles modified with alginate were served as a hydrophobic shell of the gelatin core. The formation evolution of these core–shell microspheres and its relevant factors including phase behavior of the immiscible gelatin/dextran, the binding of zein/alginate and the addition of the modified zein particles were investigated. It was found that small amount of alginate could induce zein particles to absorb on the gelatin surface, whereas the excess led to absorption competition. When using 0.6 wt% particles with zein/alginate ratio of 1:0.5, the ideal core–shell microspheres which were fully covered by the particles and with a self-supporting architecture in uniform size (18.8 ± 0.1 μm) and spherical shape were obtained. These microspheres showed remarkable stability under the conditions of heat treatment, varied pHs and salt concentrations and long-term storage either in refrigerator or room environment. Their sizes were easily manipulated by adjusting the concentration and molar mass of the biopolymers. It is believed that the desired stability and tunable sizes of these edible core–shell microspheres could contribute the development of their applications in foods.

Surface tension of graphene/Fe3O4 water-based hybrid nanofluids

Advanced hybrid nanofluids have been engineered through the synthesis of aqueous suspensions containing graphene sheets and iron oxide (Fe3O4) nanoparticles at a graphene-Fe3O4 mass ratio of 70:30. Karaya gum and cocoamidopropyl betaine (CAPB) were selected as surfactants given their good affinity with dispersed nanomaterials. Graphene sheets with Fe3O4 nanoparticles as well as the prepared dispersions were first characterized in terms of morphology, chemical composition and stability using various techniques, including electron microscopy, UV–visible spectroscopy and Zeta potential analyses. Given the crucial role that surface tension (ST) plays in boiling/condensation processes or micro-flow applications, this physical property was investigated at nanoadditive mass concentrations of 0.005–0.100 % and temperatures of 283.15–313.15 K using the pendant drop method. As an entry parameter for ST evaluation, the density of these hybrid nanofluids was also measured at the same temperature and concentration ranges. Experimental studies revealed that ST of water reduces with the addition of surfactant and increasing temperature. Graphene-Fe3O4 nanoparticles were also found to further reduce the ST (thus enhancing the effect of the surfactant mixture) by up to 42.7 % on average at 0.1 %wt. compared to water in the tested temperature range. This may be potentially interesting for improving boiling heat transfer performance and optimizing bubble flow pattern.

Carbon dioxide capture in sodium carbonate solution: Mass transfer kinetics and DTAC surfactant enhancement mechanism

Sodium carbonate solvent absorbent has been widely studied for CO2 reduction to deal with global warming because of its green, low cost, and non-corrosive advantages. However, in the application of sodium carbonate as an absorbent for CO2 capture, there is no unified cognition of the mass transfer process, which leads to the lack of guidance for the industrial large-scale process. Moreover, the mechanism of mass transfer enhancement of surfactants, which can effectively improve the mass transfer performance, has not been effectively explored in the literature. Based on this, this paper firstly adopts the molecular dynamics method to analyze the solution characteristics after surfactant addition and optimize the surfactant. Subsequently, a classical dissolved oxygen test method was used to measure the gas-liquid mass transfer coefficient for CO2 absorption into sodium carbonate solution. And based on this mass transfer coefficient measurement method, the mass transfer process of sodium carbonate solution with surfactant was analyzed. The results showed that the sodium carbonate solution with 5 wt% concentration and 10 wt% concentration at 30 °C did not satisfy the pseudo first-order fast chemical reaction kinetics assumption. To improve CO2 absorption mass transfer rate, dodecyl trimethyl ammonium chloride (DTAC) surfactant was introduced, which was improved by 119 % compared with non-enhanced solvent at 5 wt% concentration solution, and the assumption of pseudo first order fast chemical reaction was satisfied. After the introduction of surfactant, the barrier effect decreased the liquid phase mass transfer coefficient, but the Marangoni effect happened in the 5 wt% concentration of sodium carbonate solution, which enhanced the liquid-phase mass-transfer coefficient. This finding reveals the mechanism of mass transfer promotion of sodium carbonate by the surfactant DTAC, which is of great engineering significance for the application in the field of decarbonization after the introduction of surfactant.

Synthesis of urchin-like MnCo2O4 nanospheres as electrode material for supercapacitors

The morphology of MnCo2O4 has a significant effect on the electrochemical performance. In this paper, urchin-like MnCo2O4 nanospheres was successfully fabricated by a simple hydrothermal process and post-annealing treatment. The effects of addition of surfactant (Hexadecy ltrimethyl ammonium bromide) on the crystal structure, surface morphology and electrochemical performance of MnCo2O4 have been investigated. The results show that all the synthesized manganese cobalt oxides are composed of cubic spinel MnCo2O4. The addition of surfactant leads to the change of the morphology of MnCo2O4 from nanoarray to urchin-like nanospheres and increases the specific surface area, which is beneficial to improve the electrochemical performance of the MnCo2O4 electrode. The electrochemical test reveals that the urchin-like MnCo2O4 nanospheres delivered a high specific capacity of 2019 F/g at a 1 A/g and 1144 F/g at 5 A/g, respectively. The specific capacity of MnCo2O4 electrode reaches 512 F/g at 10 A/g and retains 96 % of the initial capacity after 2000 cycles at 10 A/g, which maintains an extraordinary cycling performance. In addition, an asymmetric supercapacitor (MnCo2O4//AC) with urchin-like MnCo2O4 nanospheres as a cathode and activated carbon (AC) as an anode was also assembled. Impressively, the assembled MnCo2O4//AC asymmetric supercapacitor exhibits a high energy density of 69 Wh/kg at a power density of 793 W/kg. The above research shows that the urchin-like MnCo2O4 nanospheres synthesized by adding surfactants are expected to be excellent high-performance energy storage electrode materials, which provides a new strategy for the synthesis of high-capacity nanoelectrode materials.

Theoretical and experimental insights of two surfactants’ effects on SnIn electrodeposited coatings from ethaline

This work uses computational methodologies to investigate the behavior of Sn2+ and In3+ ions in deep eutectic solvent (DES) based on choline chloride and ethylene glycol (1ChCl:2EG, ethaline), under different conditions, such as different temperatures, ion ratios, and in the presence and absence of hexadecyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS) surfactants. Furthermore, SnIn alloys were electrodeposited on Cu surfaces to analyze the effect of the investigated different conditions on the surface morphology and chemical composition of the electrodeposited coatings. Morphology and composition were analyzed using Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDS). For computational approach, twelve Molecular Dynamics (MD) simulations were conducted using the GROMACS software. After MD simulations, Quantum Theory of Atoms in Molecules (QTAIM) properties were obtained. The results presented that In3+ showed a stronger affinity for Cl− than Sn2+ but it presents weaker and less stable interactions with OA (OA = oxygen of ethylene glycol-EG), particularly at higher temperatures. Electron Density and Electron Localization Function analysis indicated that In-Cl interactions are stronger and more polarized than other interactions. The Laplacian of Electron Density suggested an intermolecular nature for all interactions. The surfactant addition altered these interactions slightly, with CTAB reducing the density of Cl− around In3+ and SDS positively interacting with In3+ at 297 K and in a Sn2+:In3+ 1:1. As SDS interacted more with In3+ ions, the electrodeposition times varied between 4965 s and 75,541 s. SEM images revealed temperature- and potential-dependent changes in film morphology, changing from globular to smooth. CTAB and SDS additions led to uniform coating in Sn2+: In3+ solutions. For the 1:1 ratio at −1.4 V, there were no significant changes (between 75 and 77 %) in the percentage of Sn deposited with the use of surfactants at 297 K. At 343 K, the surfactant-free coating exhibited 69 % Sn, CTAB facilitated the Sn deposition, increasing the percentage to 92 %. At the same time, the presence of the SDS resulted in 79 % Sn. Similar behavior was obtained for −1.0 V. For 1:4 at −1.0 V at 297 K, 35 % of Sn was observed without surfactant, 29 % with CTAB, and 33 % with SDS. At 343 K, there was an increase in Sn content for 42 %, 49 % and 60 %, indicating the positive influence of the temperature, respectively. At −1.4 V, however, there was no observed influence on the Sn percentages without surfactant. With CTAB (between 29 and 34 %) at 297 and 343 K. At these temperatures, the addition of SDS promoted a higher content of Sn, increasing to 56 % and 43 %, respectively.

Nature-Inspired Synthesis of Yeast Capsule Replicas Encased with Silica-Vinyl Functionality: New Fluorescent Hollow Hybrid Microstructures.

Yeast capsules (YCs) produced from Saccharomyces cerevisiae with encapsulated fluorescent phenosafranin and azure dyes were used as catalytic template guides for developing hybrid functional organic/inorganic hollow microstructures with silica (SiO2) deposited on their surface generated in the imidazole-buffered system without the addition of any cationic surfactant. YCs-doped with SiO2 act as fluorescence emitters maintaining dye-loaded materials by sealing the microporous surface of YCs. We used vinyltrimethoxysilane as a precursor of SiO2 endowed with functional vinyl groups facilitating their further modification without disturbing the polysaccharide wall integrity. Consequently, the hybrid fluorescent polysaccharide/silica microcapsules (YC@dye@SiO2) are promising for wide-ranging optoelectronic applications in electrochromic and OLED devices with biocompatibility and biodegradability properties.

Self-assembled flower-like spherical Bi2WO6/BiOBr S-scheme heterojunction: Improved charge transfer and excellent photocatalytic activity

The suppression of expeditious complexation of photoexcited carriers and the enhancement of light harvesting are two extraordinarily momentous elements for boosting the catalytic activity of synthesized semiconductor photocatalyst. Herein, a sequence of visible-light-induced self-assembled flower-like spherical Bi2WO6/BiOBr S-scheme heterojunctions were successfully fabricated by two-step solvothermal process. The fabricated Bi2WO6/BiOBr hybrids possessed the splendid capacity to catalyze the degradation of bisphenol A (BPA) in water without the addition of surfactant compared to monocomponent photocatalyst. The optimized Bi2WO6/BiOBr (FBBH-16) possessed the most prominent photocatalytic activity, acquiring a conspicuous degradation efficiency of 91.97 % ± 1.51 % for BPA after 60 min illumination. The rate constant k (0.04078 ± 0.0009985 min−1) of FBBH-16, which was approximately 4.0 and 3.5 times that of bare Bi2WO6 and BiOBr, respectively. Such strengthening mechanism was chiefly ascribed to the establishment of S-scheme heterojunction, which efficaciously impeded the complexation of photoexcited charge pairs and noteworthily heightened the light harvesting. Furthermore, the forceful interfacial interactions between Bi2WO6 and BiOBr afforded much more active sites for BPA removal. The quenching experiments confirmed that ·OH and ·O2− are the principal active species for BPA degradation over Bi2WO6/BiOBr hybrids. Ultimately, two possible photodegradation pathways of BPA over Bi2WO6/BiOBr heterojunctions are also come up with on the grounds of the identification of intermediate products. This work furnishes fresh insights into the fabrication of highly efficacious and stable bismuth-based S-scheme heterojunctions for treating the actual wastewater by integrating nanostructure and microscopic morphology.

Towards antimicrobial agents: Design and antibacterial activity of a hybrid fluorophore where porphyrin and Rose Bengal moieties are linked through the hydroxyl group of a xanthene dye

The axial complex of Sn(IV)-tetra(4-sulfophenyl)porphyrin (SnP) with Rose Bengal (RB) was obtained where RB axial binding is realized through the hydroxyl groups of the xanthene dye [SnP(RB)2]. The luminescent properties of the SnP(RB)2 (fluorescence and ability to generate singlet oxygen at room temperature) in aqueous media with additives of surfactant cetylpyridinium chloride (CPC) and ε-poly-l-lysine (EPL) were studied. It was found that nature of the medium (surfactant additives of different concentrations) determines the effectiveness of the photoinduced energy transfer from the RB fragment to the SnP fragment of the hybrid fluorophore (HF). It has been established that the ability of the HF to generate singlet oxygen in D2O and D2O-micellar media is higher than that of its constituent fragments. The dark and photodynamic antibacterial activity of the HF against two microorganisms [Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus)] was determined and analyzed. It was shown how the antibacterial activity of the HF depends on the nature of the bacteria, the micellar environment and radiation dose.

Surface Activity of Hydrophobized Modified Starch Hydrolysates in Mixed Systems.

The manuscript presents research focusing on the adsorption and emulsion properties of starch hydrolysates modified through acetylation, oxidation, and cross-linking. The techniques used in this study included measurements of equilibrium surface tension (du Noüy ring) dynamic surface tension (drop shape analysis), and the preparation and evaluation of emulsion stability (TURBISCAN). The surface activity of the acetylated starch hydrolysates is affected by the degree of acetylation. The acetylated starch 0.02Ac-H exhibited higher surface activity than the more highly substituted derivative 0.1Ac-H. Furthermore, it was shown that the surface activity of the components increased as the acetylated oxidized starch underwent hydrolysis. The fractions collected after 180 min using a membrane with a low separation capability (8 kDa) revealed the highest capacity for reducing surface tension. In binary systems consisting of starch derivatives and surfactants, synergistic effects in reducing surface tension were particularly noticeable in systems containing ionic surfactants. The addition of a cationic surfactant to the modified starch hydrolysate solution (1:6 mol/mol) resulted in a significantly more efficient saturation of the air/water interface. This study demonstrated that emulsions stabilized with modified starch hydrolysates remained stable over time, even when these hydrolysates constituted up to 60% of the emulsifier mixture.

Transient transition from Stable to Dissipative Assemblies in Response to the Spatiotemporal Availability of a Chemical Fuel

AbstractThe transition from inactive to active matter implies a transition from thermodynamically stable to energy‐dissipating structures. Here, we show how the spatiotemporal availability of a chemical fuel causes a thermodynamically stable self‐assembled structure to transiently pass to an energy‐dissipating state. The system relies on the local injection of a weak affinity phosphodiester substrate into an agarose hydrogel containing surfactant‐based structures templated by ATP. Injection of substrate leads to the inclusion of additional surfactant molecules in the assemblies leading to the formation of catalytic hotspots for substrate conversion. After the local disappearance of the substrate as a result of chemical conversion and diffusion the assemblies spontaneously return to the stable state, which can be reactivated upon the injection of a new batch of fuel. The study illustrates how a dissipating self‐assembled system can cope with the intermittent availability of chemical energy without compromising long‐term structural stability.

Transient transition from stable to dissipative assemblies in response to the spatiotemporal availability of a chemical fuel.

The transition from inactive to active matter implies a transition from thermodynamically stable to energy-dissipating structures. Here, we show how the spatiotemporal availability of a chemical fuel causes a thermodynamically stable self-assembled structure to transiently pass to an energy-dissipating state. The system relies on the local injection of a weak affinity phosphodiester substrate into an agarose hydrogel containing surfactant-based structures templated by ATP. Injection of substrate leads to the inclusion of additional surfactant molecules in the assemblies leading to the formation of catalytic hotspots for substrate conversion. After the local disappearance of the substrate as a result of chemical conversion and diffusion the assemblies spontaneously return to the stable state, which can be reactivated upon the injection of a new batch of fuel. The study illustrates how a dissipating self-assembled system can cope with the intermittent availability of chemical energy without compromising long-term structural stability.

Study on the synergism mechanism of composite surfactants for oily sludge treatment using microemulsion method

The nonionic surfactant was considered to be the most effective surfactant for the treatment of oily sludge. In this paper, Tween20 and Span80 (T/S) composite surfactant was chosen as emulsifier for the preparation of microemulsion, and their synergistic effect was explored. Clint equation and molecular dynamics simulation was used to interpret the formation of mixed micelles and the results showed that T/S composite surfactant with the mass ratio of 11:1 exhibited the good synergetic effect. Then, the microemulsion prepared using composite surfactants was applied for the treatment of oily sludge. Under the optimal conditions of solid-liquid ratio of 1:1(g: mL), stirring temperature of 40 °C, stirring time of 30 min and stirring speed of 400 rpm, the residual oil rate was reduced to 0.25%, which was much lower than other reported results using chemical methods. Interface tensiometer and quartz crystal microbalance measurement showed that the interfacial tension decreased significantly after the addition of composite surfactant. This work provides a feasible strategy for oily sludge treatment using microemulsion, which promoted the development of oily sludge treatment processes based on microemulsion in practical industry.

Deciphering the Influence of Zwitterionic Surfactants on Pluronic Co-assemblies: A Synergistic Odyssey through Spectroscopic, Microscopic, and Scattering Techniques.

Fundamental investigations into the photophysical properties and microenvironmental features of pluronic-zwitterionic surfactant mixed assemblies are essential for advancing our understanding of molecular interactions at the nanoscale, setting the stage for innovative solutions in drug delivery, diagnostics, and other applications of pluronic-zwitterionic surfactant assemblies. This investigation explores the intricate photophysics of pluronic-zwitterionic surfactant mixed assemblies, utilizing the twisted intramolecular charge transfer state forming styryl dye trans-2-[(4-dimethylamino) styryl] benzothiazole as a probe. By comparing the behaviors of two distinct poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) block copolymers with block composition of (PEO)132-(PPO)50-(PEO)132 [F108] and (PEO)100-(PPO)65-(PEO)100 [F127] at concentrations of 5 and 10 wt %, this study systematically examines the impact of the addition of zwitterionic surfactants. Through a comprehensive set of analytical techniques, including UV-visible absorption, steady-state emission, and time-resolved fluorescence emission studies, significant alterations in the emission spectra and quantum yields were observed upon the addition of zwitterionic surfactants. These modifications suggest a dynamic equilibrium for the transitioning of dye molecules between various microenvironments within the assemblies. Additionally, dynamic light scattering, zeta potential (ζ), nuclear Overhauser effect spectroscopy, small-angle neutron scattering, cryogenic transmission electron microscopy, field emission scanning electron microscopy, and fluorescence lifetime imaging microscopy analyses have shed light on the substantial impact of surfactant incorporation on the structural properties of assemblies.

Harnessing the Potential of Morphologically Tailored ZnSn(OH)6 Nanograss Photoanode for Solar‐Driven Water Splitting

AbstractHydrothermal growth of ZnSn(OH)6 nanograss on ZnO‐coated FTO substrates is demonstrated. Effect of surfactants addition (polyvinylpyrrolidone and polyethylene glycol), precursor concentration, and reaction temperature on surface morphology of ZnSn(OH)6 nanograss are investigated. Addition of surfactant in precursor solution results in growth of approximately 20–30 nm thick nanograss morphology with varying orientation. The nanograss grow longer by increasing the concentration of precursors solution. The grown ZnSn(OH)6, exhibits XRD peaks corresponding to cubic phase ZnSn(OH)6. Optical bandgap of the grown nanograss are calculated in the range from ∼3.0 to 3.5 eV. The nanograss photoanode grown with PEG surfactant (at 200 °C) has shown the highest photocurrent of 2.2 mA/cm2 at RHE 1.23VRHE and photoconversion efficiency of 1.4% at 0.46 VRHE. The longer nanograss has shown lower charge transfer resistance and higher charge carrier concentration, which is favorable for enhancing the PEC performance.

Ferrofluid Droplet Chains in Thermotropic Nematic Liquid Crystals.

Dispersing ferrofluids in liquid crystals (LCs) produces unique systems which possess magnetic functionality and novel phenomena such as droplet chaining. This work reports the formation of ferrofluid droplet chains facilitated by the topological defects within the LC director field, induced by the dispersed ferrofluid. The translational and rotational motion of these chains could be controlled via application of external magnetic fields. The process of the droplet chain formation in LCs can be stabilized by the addition of surfactants. The magnetic colloidal particles in the ferrofluid located at the interface between the ferrofluid and the LC are arranged so that a boundary layer was formed. The velocities and boundary layer thickness values of ferrofluid droplet chains in nematic 5CB (4-Cyano-4'-pentylbiphenyl) were investigated for varying average droplet sizes and number of droplets in a chain. The creation and behaviour of ferrofluid droplet chains in 5CB with the addition of the surfactant polysorbate 60 (Tween-60) and without, was comparatively investigated. The integration of liquid crystals and ferrofluids along with the incorporation of functional materials facilitates the innovative development of advanced materials for future applications.

Thin liquid film stability in the presence of bottom topography and surfactant

We consider gravity-driven fluid flow down a wavy inclined surface in the presence of surfactant. The periodicity of the bottom topography allows us to leverage Floquet theory to determine the form of the solution to the linearized governing partial differential equations. The result is that perturbations from steady state are wavelike, and a dispersion relation is identified which relates the wavenumber of an initial perturbation, κ, to its complex frequency, ω. The real part of ω provides a criterion for determining linear flow stability. We observe that the addition of surfactant generally has a stabilizing effect on the flow, but has a destabilizing effect for small wavenumbers. These results are compared and validated against numerical simulations of the nonlinear system. The linear and nonlinear analyses show good agreement, except at small wavenumbers, where the linear results could not be replicated.

Mesoscale modeling on the influence of surfactants on seepage law during water injection in coal

To investigate the mesoscopic influence of surfactants on seepage law during water injection in coal seam, this paper innovatively establishes a fluid transport lattice Boltzmann (LBM) model by incorporating the seepage resistance generated from the porous media and external forces, which embodies the impact of wettability degree resulted from cocamidopropyl betaine (CAB), sodium dodecyl sulfate (SDS), and coconutt diethanol amide (CDEA) reagents at a 0.1% concentration. The main conclusions derived from this investigation are as follows: Firstly, as the lattice number in the X direction increases, the average seepage velocities in coal samples treated by deionized water, 0.1% CAB, 0.1% SDS, and 0.1% CDEA reagents (Nos. 1, 2, 3, and 4) exhibit three distinct stages: rapid decline, slow decline, and steady decline; in comparison to raw coal sample, modified coal samples demonstrate decreases of 20.84%, 33.91%, and 61.70%, respectively. Secondly, the critical values of displacement pressure difference exist during the phenomenon that modified reagents spread out in the entire flow channel, which are 3.5, 3.5, and 5.2 MPa, respectively, for coal samples Nos. 2, 3, and 4; this signifies that surpassing these critical values help prevent issues such as blank belts within the wetting range and insufficient dust control. Finally, at a displacement pressure difference of 0.01 (lattice unit), the average velocity ratios for samples (Nos. 2, 3, and 4) are 0.78, 0.56, and 0.37 (lattice unit), respectively; notably, the water flow velocities in modified coal samples are lower compared to that in raw coal sample, indicating that the addition of surfactants impede the seepage process of water injection in coal seam. Moreover, when the displacement pressure difference reaches 0.03 (lattice unit), the velocity ratio of CDEA-modified coal sample exceeds 100%; this means that when the displacement pressure difference surpasses 15.6 MPa, the water injection effect of CDEA-modified coal sample begins to be improved. These research findings offer a theoretical basis for enhancing water injection technology in coal mines.