Effects Of Surface Acting Research Articles

Enzymatic synthesis of stachyose-derived fatty acid mono-esters, the evaluation of their surface and interfacial properties and the capacity of certain derived emulsions to deliver resveratrol.

The nutritional characteristics of the tetrasaccharide stachyose prompted its incorporation into biosurfactants through esterification with fatty acid derivatives embodying 12-22 carbon chains. The resulting esters were evaluated for their surface active effects, emulsifying properties and capacities to form emulsions capable of the selective delivery of the anti-oxidant resveratrol. While such studies have revealed that those congeners embodying longer side-chains have higher critical micelle concentrations (CMC) and lower interfacial tensions, their hydrophilic-lipophilic balance (HLB) values fell within a tight range. Those emulsions stabilized by esters with medium and longer side-chains exhibited good stabilities over the pH range 6-10 and up to 95°C. Assessments of the in vitro digestion of the corresponding emulsions charged with resveratrol revealed the bioavailability of the anti-oxidant reached ca. 80% and so suggesting that the title stachyose esters are distinctive and promising sugar-based surfactants for the targeted delivery of functional foods.

Insight into Oil-in-Water Emulsions Stabilized by Cross-Linked and Pregelatinized Starches: The Effect of Molecular Structure, Surface Activity and Proton Molecular Dynamics.

Effective formation and stabilisation of emulsions while meeting high consumer requirements, including the so-called green label, is still a technological challenge. This is related to the multitude of emulsion destabilization mechanisms and the vastness of methods used to study them, which implies the need to develop an understanding of the phenomena occurring in emulsions. Commercial starch preparations obtained by physical and chemical modification were used to prepare model emulsions that were studied in terms of their stability. Native potato starch was the reference material. The analytical methods used included rheology, low field nuclear magnetic resonance (LF NMR), size exclusion chromatography with triple detection (SEC), and surface/interfacial tension measurements. The results showed that chemical and physical modification improved the functionality of starch in emulsions. This is due to not only chemical but also physical modifications, i.e., pregelatinization causes changes in the molecular structure of starch, including an increase in the molecular weight and the degree of branching. As a consequence, the conformation of starch macromolecules changes, which results in a change of the dynamics of protons in the continuous phase of the emulsion and the thermodynamics of starch adsorption at the water/oil interface.

Influence of CO2 on asphaltene adsorption dynamics at the Oil-Gas Interface: New insights into precipitation and aggregation processes

To investigate the effect of CO2 on the precipitation of asphaltene in oil, and verify the advantages of CO2 flooding, this work designs interfacial tension experiments and PVT system experiments to create the experimental environment under different temperature and pressure conditions that make CO2 contact with oil. The results indicate that CO2 can affect the oil morphology, and the trend of oil volume increase and decrease depends on the dynamic balance between the expansion effect and the component extraction effect of CO2 on oil. Under low pressure, the oil expansion caused by dissolved CO2 dominates the experiments, increasing the oil volume. Under high pressure, sufficient CO2 in the oil activates its component extraction effect, and the asphaltene in the oil precipitates and accumulates at the interface between the oil and CO2 due to the disruption of the component equilibrium of the system, exerting a surface activity effect, leading to a decrease in oil volume. Due to the movement of asphaltene towards the system interface and the formation of an asphaltene film during this stage, which hinders the entry of CO2 into the oil, the interfacial tension shows three linear decreasing trends with increasing pressure. This mechanism also changes the variation trend of the oil volume in CO2 during the pressure increase. Moreover, the components of the oil extracted by CO2 will be transferred to CO2, making its properties similar to oil. With the reduction of interfacial tension, this process promotes the miscibility between the two. These effects verify that CO2 can improve the fluidity and quality of oil during reservoir development, and reduce or even eliminate the adhesion work required for the working fluid to displace the oil. These conditions are conducive to improving reservoir development efficiency, reflecting the great application value of CO2 flooding.

Mechanochemical modeling of morphogenesis in cell polarization for budding yeast

Cell polarization is a multiphysics problem resulting from coupling protein pathways and cell morphological evolution. The most common example is asexual reproduction in budding yeast through Cdc42 and septin signals. However, how the interaction between the Cdc42-septin systems and the mechanical deformation of the cell surface is not well understood. To explore the interaction, we build a three-dimensional mechanochemical coupling framework to investigate the Cdc42-septin systems and elucidate how morphogenesis at the cell scale enhances the robustness of cell polarization in budding yeast. We utilize the viscous active shell model to describe the moving boundary of the cell surface, and the mechanochemical coupling is achieved through the introduction of cell surface mean curvature and active contraction-growth effects. With a normal effect of septin, numerical results demonstrate the budding processes with different transition shapes of budding profiles. On the other hand, the mechanochemical coupling problem with a weak effect of septin drives the emergence of wrinkles on the cell surface. We also apply linear perturbation analysis of the cell surface deformation to show how cell shape evolution is subjected to active contraction-growth effects. Our results show that a 3D coupled mechanochemical model can reproduce the budding morphology in yeast. Such a model provides a more comprehensive portrait of cell polarity and can be used to characterize both wild-type and mutant phenotypes such as septin mutants.

Effect of surface activity of recycled fine aggregates from clay bricks on the hydration, microstructure and chloride transport of concrete

Use of recycled fine aggregates from clay bricks (RFCB) in the preparation of eco-friendly concrete was proposed to tackle the river sand (RS) shortage and satisfy the construction demand. This study explored the surface activity of RFCB influenced by additional water and particle size distribution (PSD) on the hydration, microstructure and chloride transport of concrete. Compared to the RS, more silica and alumina released from RFCB depending on its PSD under alkaline environment was noted, which verified its appreciable surface activity. Overall, the presence of RFCB could hinder early hydration process because of the higher additional water, while the surface activity and nucleation effect supplied from finer RFCB were beneficial for the improvement of the hydration kinetics. Furthermore, inclusion of RFCB increased the total pore volume and porosity but performed better in refining the pore size distribution, thus decreased the average pore diameter. The surface activity of RFCB decreased CH content while increased chemical bond water and additional hydrates, thereby leading to enhancement of the compactness of interface, cement matrix and surface rim. More importantly, RFCB helped to decrease the chloride migration coefficient and electric flux. Though the surface activity of RFCB was beneficial in the strength development, it could not offset a deteriorated influence of porous RFCB with a higher replacement.

First Cu-nanostar as a sustainable catalyst realized through synergistic effects of bowl-shaped features and surface activation of sporopollenin exine.

Recently, nanostar-shaped structures, including gold nanostars (NS), have drawn much attention for their potential use in surface-enhanced Raman spectroscopy (SERS) and catalysis. Yet, very few studies have been conducted on Cu-Au hybrid NS, and there are none for Cu-based NS. Herein, we describe an effective method for controlling copper-oxide nanostar (ESP-PEI-CuI/IIO-NS) growth using sporopollenin as a sustainable template material. However, ESP-PEI-CuI/IIO-NS growth depends on sporopollenin surface functionalization. Sporopollenin surface activation was done by amine functionalization with polyethyleneimine (PEI), without which ESP-PEI-CuI/IIO-NS growth was not observed. The sporopollenin's exine (outer wall) has a bowl-like structure, which mediates the growth of Cu nanorods, resulting in an NS morphology. Furthermore, due to their increased surface area, ESP-PEI-CuI/IIO-NS showed excellent catalytic activity for Huisgen 1,3-dipolar cycloadditions even when used in H2O and without additives under green conditions. This approach utilising biomass as a sustainable template would pave the way for developing controlled growth of nanostructures for SERS-related and catalytic applications.

Performance characterization of water extracts of Camellia oleifera cake/sodium N-lauroylsarcosinate foam detergent with high foamability

In this study, we hypothesized that an environment-friendly foam detergent with synergistic effects could be synthesized from saponins-rich water extracts (WE) of Camellia oleifera cake, sodium N-lauroylsarcosinate (SLS), citric acid (CA), and ethanol. The ratio of WE and SLS was optimized by comparing the foam properties and cleaning efficiency. The synergistic effect was elucidated by viscosity, surface tension, zeta potential, contact angle, and particle size. The effects of ethanol and CA on the foam properties and cleaning efficiency were also studied, and the potential mechanism was analyzed. The results showed that SLS-WE (3−1) with the strongest foamability had the highest cleaning efficiency (82.8%) for olive oil. This is related to the synergistic effects of surface activity between WE and SLS. The addition of WE improved the foam elasticity and yield stress of the mixture system, thus preventing secondary contamination. The addition of CA (0.1 wt%), ethanol (3.7 wt%), and CA/ethanol (0.1/3.7 wt%) improved the foamability with no negative effect on foam stability. The cleaning efficiency of foam detergent reached 93.7% under the mixture of CA and ethanol. The SLS-WE (3−1) system improved the oil imbibition of foam by reducing surface tension and bubble size. Moreover, the SLS-WE (3−1) foam had a strong wiping motion. Ethanol and citric acid increased cleaning efficiency by improving imbibition and wiping, respectively. The environmentally friendly foam detergent fabricated in this research exhibited high foamability, stability, and cleaning efficiency.

Effect of Surface Activation on the Microstructure and Corrosion Resistance of MAO/Ni-P Composite Coating on AZ91D Magnesium Alloy.

The purpose of this study is to improve the number and distribution of active particles on the MAO layer by changing the activation method, thus improving the corrosion resistance of the coating. The structure of the coatings was characterized by SEM, XRD, XPS, and AFM, as well as the corrosion resistance of the coatings by polarization curves, EIS tests, immersion tests, and salt spray tests. The conductive resistance and adhesion of different composite coatings were compared. The results demonstrate that the properties of the composite coating are significantly affected by different activation methods, and the Ni-P coating prepared with more active particles offers superior corrosion protection to the inner layer. The quantity and distribution of active particles affect the compactness of the coating by influencing the initial deposition process. The size of nickel particles is larger and the inter-grain porosity increases in the case of fewer active sites, and as the number of active sites increases, the size of nickel particles decreases, and the coating compactness increases. The mechanism of the effect of the number of active particles on the deposition process of electroless Ni-P coating was proposed.

Functionality of hydrophobic groups of surfactants in the flotation of anode active materials

In the present paper, the effect of surface activity and the role of hydrophobic groups of four different frothers (2-octanol, terpenic oil, methyl isobutyl carbinol (MIBC), and sodium dodecyl benzene sulfonate (SDBS)) on the collector-less floatability of anode-active materials were studied. Fourier-transform infrared spectroscopy (FTIR) and zeta potential analyses were applied to detect functional groups and particle surface charge, respectively. The floatability of the material was examined using an XFG flotation cell in the absence and presence of these frothers. The experimental results showed that the functional groups on the surface of anode active materials (AAM) including CH3, C-O-O, and aromatic rings reacted with a frother and increased the recovery of the particles by 15%. Also, the presence of phenolic resin on the particle surface caused the functional groups on the surface of the particles to interact with frother molecules and improved the recovery of the particles by acting as a collector. Furthermore, the zeta potential of the particles after the addition of surfactant (at pH 7) showed a negative shift because of the particle hydrophobicity and agglomeration of particles. In addition, the results of contact angle and FTIR analyses showed that materials had a greater contact angle after using various surfactants and successful interaction occurred between the AAM surface and the hydrocarbon tail of the surfactants. The flotation results demonstrated that the recovery of AAM without any surfactants was zero but it was increased as the following order of 2-octanol ≫ terpenic oil > SDBS > MIBC.

Exploration on structural stability, electronic and optical properties of Cs-activated and Cs/O-activated Al0.5Ga0.5N thin film and nanowire photocathode surface

To explore effects of surface activation on AlGaN-based photocathode, this paper analyzes in detail the structural stability, charge transfer, band structure, density of states, absorption coefficient and reflectivity of Cs-activated and Cs/O-activated Al0.5Ga0.5N thin films and nanowires by using first-principles. Our results reveal that adsorption energy of Al0.5Ga0.5N thin films and nanowires adsorbed by Cs will gradually increase as Cs coverage increases, and structural stability will be weakened. Cs-adsorbed thin film surfaces are more stable than nanowire when Cs coverage is same. Cs/O co-adsorbed Al0.5Ga0.5N systems are more stable under high Cs coverage. And Cs/O co-adsorbed Al0.5Ga0.5N possess the most stable structure when the ratio of Cs to O is 2:1. Band structure and density of states imply that Cs and O adsorption introduce new energy levels, which are derived from s, p orbitals of Cs and s orbitals of O, respectively. Furthermore, only when the Cs/O ratio is 2:1, the work function of Al0.5Ga0.5N thin film is lower than that of Cs-only adsorption, which is conducive to electron escape and improving quantum efficiency. Results of optical properties show that Cs activation and Cs/O activation can greatly improve the optical performance of Al0.5Ga0.5N.

Biodegradable MOFilters for Effective Air Filtration and Sterilization by Coupling MOF Functionalization and Mechanical Polarization of Fibrous Poly(lactic acid).

High-performance air filtration materials are important for addressing the airborne pollutants. Herein, we propose an unprecedented access to biodegradable poly(lactic acid) (PLA)-based MOFilters with excellent filtering performance and antibacterial activity. The fabrication involved a stepwise in situ growth of zeolitic imidazolate framework-8 (ZIF-8) crystals at the surface of microfibrous PLA membranes, followed by mechanical polarization under high pressure and low temperature (5 MPa, 40 °C) to trigger the ordered alignment of dipoles in PLA chains and ZIF-8. The unique structural features allowed these PLA-based MOFilters to achieve an exceptional combination of excellent tensile properties, high dielectric constant (up to 2.4 F/m), and enhanced surface potential as high as 4 kV. Arising from the remarkable surface activity and electrostatic adsorption effect, a significant increase (from over 12% to nearly 20%) in PM0.3 filtration efficiency was observed for the PLA-based MOFilters compared to that of pure PLA counterparts, with weak relation to the airflow velocities (10-85 L/min). Moreover, the air resistance was controlled at a considerably low level for all the MOFilters, that is, below 183 Pa even at 85 L/min. It is worth noting that distinct antibacterial properties were achieved for the MOFilters, as illustrated by the inhibitive rates of 87 and 100% against Escherichia coli and Staphylococcus aureus, respectively. The proposed concept of PLA-based MOFilters offers unprecedented multifunction integration, which may fuel the development of biodegradable versatile filters with high capturing and antibacterial performances yet desirable manufacturing feasibility.

Effect of Surface Activation on the Corrosion Resistance of a MAO/Ni-P Composite Coating on LZ91 Magnesium Alloy

BackgroundLZ91 Magnesium alloy with a dual-phase structure has improved mechanical properties and a low density of about 1.48 g/cm3 but their limited resistance to corrosion limits their application. Therefore, it is a great challenge to increase the stability of LZ91 alloys under corrosive factors and environments. MethodsThis study uses micro-arc oxidation (MAO) and an electroless nickel-phosphorus (Ni-P) plated composite film to increase the corrosion resistance of LZ91 magnesium alloy. Before electroless Ni-P plating, the MAO layers are activated by palladium catalysts at different pH values to produce composite coatings. SEM, EDS and Image J are used to determine the surface properties and elemental composition of the samples. The corrosion resistance is measured using a potentiodynamic polarization test and electrochemical impedance spectroscopy (EIS) in 3.5 wt.% NaCl solution. FindingsThe results show that the MAO coating is activated by an acid catalyst and the surface is obviously corroded. The electroless Ni-P plating grows into the MAO coating and the substrate corrodes. Therefore, corrosive medium (chloride ion) easily enter to the substrate and pitting corrosion occurred. On the contrary, activation by a neutral catalyst (pH=7) maintains the original structure of the MAO coating and provides a good bonding interface for the Ni-P coating. Form the potentiodynamic analysis can be finds that the corrosion potential for the neutral catalyst treated sample is -0.35V and the corrosion current density value is 1.77×10−6 A/cm2, so the corrosion characteristic become better than the acid catalyst treated samples. In terms of the long-term resistance after 48 h, EIS analysis shows that the resistance value remains at about 7.6×104 Ω•cm2. A composite coating that is compact and with excellent resistance to corrosion resistance is produced, which provides better protection for LZ91 magnesium alloys.

Pickering emulsions produced with kraft lignin colloids destabilized by in situ pH shift: Effect of emulsification energy input and stabilization mechanism

We introduce Kraft lignin colloids produced by destabilization of a kraft lignin solution by pH shift from 2 to 11. The system includes lignin particles and hydrocolloid aggregates in equilibrium (KLP), which are used to control the emulsifying energy and to stabilize oil-in-water emulsions under high energy at pH 11 and 7, yielding excellent stability (at least three months with no creaming). We investigate emulsify technology (ultrasonication and homogenization), energy input (high energy or low energy), particle desorption, drop size, and rheology on the stability of KLP-based Pickering emulsions according to the system’s pH. The ultrasonication leads to fine, stable and homogenous lignin emulsions without observing macroscopic creaming phenomenon, whereas homogenization only limits to alkaline condition. Regarding homogenization process, increasing the energy input helps to reduce the emulsion droplet size and consequently improves emulsion stability. In addition, the emulsion produced at acidic conditions always presented excellent stability, independent of the emulsify parameters. Considering the synergistic effects of emulsification protocol, surface activity, and particle interactions, the results indicate the possibility of extending the applications of kraft lignin as a Pickering stabilizer in neutral and alkaline conditions. It also creates a promising method to control the stability and emulsion microstructure in the industrial KLP based emulsion preparation process.

Comparative study on structure and electronic properties of Al0.5Ga0.5N thin film and nanowire photocathode under surface oxidation

Oxidation will generate higher surface barriers and new surface states, resulting in declined electron escape probability and electron emission performance, which seriously affects surface activation effect of the photocathode. In order to explore the effects of oxidation on Al0.5Ga0.5N thin film photocathodes and nanowire photocathodes, we have analyzed structure and electronic properties of Al0.5Ga0.5N thin film and nanowire under oxidation. The results show that formation energies of Al0.5Ga0.5N film oxidation surface is negative in both O-rich and O-poor conditions under O adsorption, indicating that surface of Al0.5Ga0.5N film is easily oxidized. However, Al0.5Ga0.5N nanowires are easily oxidized only when O concentration is higher. The formation energies of oxygen substitution model are all positive, indicating that this form of oxide is not easy to form on the surface. The results of band structure and PDOS indicate that pristine Al0.5Ga0.5N film has abundant surface states near the Fermi level. After oxygen adsorption, Ga atoms form stable Ga–O bonds with O atoms and the surface states are weakened. For oxygen substitutional oxidation, compared to Al0.5Ga0.5N thin film, conduction band of Al0.5Ga0.5N nanowire splits to form more energy levels and CBM moves downward, forming an n-type surface, which is not conducive to photoelectric emission.

Room temperature bonding of Au assisted by self-assembled monolayer

The surface activated bonding (SAB) technique enables room temperature bonding of metals, such as Au, by forming metal bonds between clean and reactive surfaces. However, the re-adsorption on the activated surface deteriorates the bonding quality, which limits the applicability of SAB for actual packaging processes of electronics. In this study, we propose and demonstrate the prolongation of the surface activation effect for room temperature bonding of Au by utilizing a self-assembled monolayer (SAM) protection. While the bonding without SAM fails after exposure of the activated Au surface to ambient air, the room temperature bonding is achieved using SAM protection even after 100 h exposure. The surface analysis reveals that the clean and activated Au surface is protected from re-adsorption by SAM. This technique will provide an approach of time-independent bonding of Au at room temperature.

Activating the (101) facets of Cu2WS4 in the CdS/Cu2WS4 S-scheme heterojunction to enhance the photocatalytic hydrogen evolution activity

Due to the synergistic effect of (101) crystal surface activation and S-scheme heterojunction, the CdS/Cu2WS4 heterojunction exhibits surprisingly high hydrogen evolution activity.

Customer misbehavior and service employees' emotional exhaustion: Effects of surface acting, involvement, and mental elasticity

Employees in service-oriented enterprises often face the social stressor of customer misbehavior. On the basis of survey data from 503 service employees, we drew the following conclusions: (a) multidimensional customer misbehavior can be replaced by a second-order factor, and customer misbehavior has a significant promoting effect on employees' emotional exhaustion; (b) employees' surface acting mediates the impact of customer misbehavior on employees' emotional exhaustion; (c) employees' involvement acts as a moderator between customer misbehavior and employees' surface acting; and (d) employees' mental elasticity has a moderating effect between their surface acting and their emotional exhaustion. According to the research results, managers of enterprises can take targeted measures to minimize the impact of customer misbehavior on the emotional exhaustion of service employees, thus ensuring the physical and mental health of these employees.

Effect of decontamination materials on bond strength of saliva-contaminated CAD/CAM resin block and dentin.

The aim of this study was to evaluate the effect of decontamination agents against saliva contamination on the bonding of computer-aided design/computer-aided manufacturing (CAD/CAM) resin block. Three commercially available decontamination agents were used in this study. The samples were subjected to microtensile bond strength test. A saliva protein staining test was performed by the pigment binding method to investigate the effect of removing saliva protein. All the decontamination agents could significantly restore the bond strength from the saliva contamination, and KATANA Cleaner showed no significant difference with the control. From the results of the saliva protein staining test, KATANA Cleaner showed higher removal effect of saliva protein for CAD/CAM resin block surface than the other materials due to the surface active effect of MDP salt. It was suggested that cleaners containing MDP salt were more effective in removing artificial saliva contamination than cleaners containing other ingredients for CAD/CAM resin blocks.

(Digital Presentation) Kinetic Studies of Aorfb Posolyte on Graphite Micro-Fiber Electrodes

Aqueous organic electrolytes used as posolyte for redox flow battery applications are growing in interest due to their fast kinetics on carbon materials. The determination of their kinetic constants remains a necessity for a better understanding of their overall electrochemical behavior but also for a fine evaluation of the effect of surface activation and possible electrode aging during cycling.However, the studies performed on carbon felts have shown a lack of accuracy due to the macro-porosity and high surface area of these materials, even at very low electrolyte concentrations (10-4 M). Thus, in this study, we propose another system, allowing to shift from the macro to the micro scale: microelectrodes prepared with single fibers extracted from the corresponding graphite porous felt [1-2]. These microelectrodes allow the qualitative study of solutions at higher concentrations (up to 0.5 M in K4[Fe(CN)6]) and a quantitative analysis through EIS and CV modelling for solutions at 10-2 M with the determination of kinetic constants on activated and non-activated single fibers.In addition, the effect of activation treatments of graphite felts, on the oxidation kinetics of ferrocyanide is investigated through cyclic voltammetry. In fact, this method allows to determine optimal treatment conditions of carbon felts for a better performance of the battery. Moreover, the degradation of the activation over time can be also studied, which means that the same method could be applied for the study of the aging of the felt after cycling in the battery.

Direct Bonding Method for Completely Cured Polyimide by Surface Activation and Wetting.

Polymer adhesives have emerged as a promising dielectric passivation layer in hybrid bonding for 3D integration, but they raise misalignment problems during curing. In this work, the synergistic effect of oxygen plasma surface activation and wetting is utilized to achieve bonding between completed cured polyimides. The optimized process achieves a void-less bonding with a maximum shear strength of 35.3 MPa at a low temperature of 250 °C in merely 2 min, significantly shortening the bonding period and decreasing thermal stress. It is found that the plasma activation generates hydrophilic groups on the polyimide surface, and the wetting process further introduces more −OH groups and water molecules on the activated polyimide surface. The synergistic process of plasma activation and wetting facilitates the bridging of polyimide interfaces to achieve bonding, providing an alternative path for adhesive bonding in 3D integration.