Changes In Interfacial Properties Research Articles

Experimental and mechanism study of asphaltene on formation and stabilization of oil-based foam

Stable foam will be generated in the separation equipment after pressure reduction of crude oil, which reduce the separation efficiency and damage the power equipment. It is found that the foam formed by asphaltene-rich crude oil is particularly stable in oilfield production, and the action mechanism of asphaltene for foam remains unclear. Hence, a self-made foaming device was performed to investigate the foamability and foam stability of oil-based foam, and the impact of asphaltene concentration and oil phase composition on foam properties was elucidated from the interfacial properties, viscosity, foam structure and the microstructure of asphaltene. Results show that low asphaltene concentrations promote foaming and mitigate the foam destruction. In contrast, high asphaltene concentrations are detrimental to foaming and reduce foam stability. The changes in interfacial properties and viscosity caused by asphaltene are not the main factors affecting foam performance. Besides, we proposed that asphaltene present in the oil phase as non-adsorbed particle, and the foam stability is influenced by the shape, volume fraction and size distribution of the particles. Furthermore, the boundary conditions for the effect of asphaltene on foam performance are innovatively put forward. This work contributes to understand the mechanism by which the asphaltene enhances foam stability and provides theoretical support for defoaming techniques in crude oil foam.

Effect of Different Polymerization Degrees and Fatty Acids of Polyglycerol Esters on the Physical Properties and Whippability of Recombined Dairy Cream.

Polyglycerol esters (PGEs) are used as emulsifiers in recombined dairy cream (RDC) to improve product quality. In this study, the effects of four PGEs with different polymerization degrees and esterification on the particle size, viscosity, zeta potential, and microrheology of RDC emulsions were investigated, and the whipping time, overrun, serum loss, and firmness of the RDC emulsions were recorded. The results show that the addition of the PGEs reduced the particle size (from 2.75 μm to 1.48-1.73 μm) and increased the viscosity (from 41.92 cP to 73.50-100 cP) and stability (from 0.354 to 0.105-0.128), which were related to the change in interfacial properties and the weakening of Brownian motion, but there were differences in the effect on the whipping behavior of the RDCs. Although the addition of 0.9% triglyceride monolaurate gave the emulsion the best stability, the RDC had a longer whipping time (318 s) and a lower overrun (116.6%). Comparatively, the 0.7-0.9% concentrations of PGE55 and tripolycerol monostearate (TMS) provided RDC with good stability and aeration characteristics, allowing inflation within 100 s and expansion rates of up to 218.24% and 186.88%, respectively. In addition, the higher degree of polymerization of polyglyceryl-10 monstearate (PMS) did not work well at any concentration. These results contribute to understanding the mechanism of action of PGEs and improving the quality of RDC.

Relating the kinetics of grain-boundary complexion transitions and abnormal grain growth: A Monte Carlo time-temperature-transformation approach

Grain boundaries undergo thermally-activated, first-order transitions that result in discontinuous changes of interfacial properties. Importantly, grain boundary transitions lead to changes in bulk material properties (e.g., embrittlement) and/or behavior (e.g., abnormal grain growth). Numerous studies have been completed on the equilibrium states of grain boundaries and their transitions (i.e., complexion transitions), but there have been far fewer investigations of complexion transition kinetics; complexion transitions occur on the atomic-scale and are therefore challenging to detect experimentally. In this work, a 3D Potts grain growth model with stochastic complexion transitions was employed to investigate complexion transition kinetics. A Johnson-Mehl-Avrami-Kolmogorov (i.e., JMAK) approach was used to extract nucleation and growth rates (i.e., transformation rates), while point process analyses and correlation functions were used to infer complex interrelated nucleation and growth events. Time-temperature-transformation (TTT) diagrams, in particular grain-boundary complexion, transformed grain, and abnormal grain TTT diagrams, were constructed to summarize the progress of complexion-related transformations. Such diagrams relate complexion-induced grain growth to the underlying complexion transitions and, in the case of abnormal grain growth (AGG), permit one to assess the role of AGG as a temperature-dependent, time-displaced indicator of complexion transitions. Overall, this work details a theoretical framework that can be used to better understand complexion transition kinetics as well as to develop tools for the design of bulk microstructures.

Nanomechanical sensor for rapid and ultrasensitive detection of tumor markers in serum using nanobody.

Early cancer diagnosis requires ultrasensitive detection of tumor markers in blood. To this end, we develop a novel microcantilever immunosensor using nanobodies (Nbs) as receptors. As the smallest antibody (Ab) entity comprising an intact antigen-binding site, Nbs achieve dense receptor layers and short distances between antigen-binding regions and sensor surfaces, which significantly elevate the generation and transmission of surface stress. Owing to the inherent thiol group at the C-terminus, Nbs are covalently immobilized on microcantilever surfaces in directed orientation via one-step reaction, which further enhances the stress generation. For microcantilever-based nanomechanical sensor, these advantages dramatically increase the sensor sensitivity. Thus, Nb-functionalized microcantilevers can detect picomolar concentrations of tumor markers with three orders of magnitude higher sensitivity, when compared with conventional Ab-functionalized microcantilevers. This proof-of-concept study demonstrates an ultrasensitive, label-free, rapid, and low-cost method for tumor marker detection. Moreover, interestingly, we find Nb inactivation on sensor interfaces when using macromolecule blocking reagents. The adsorption-induced inactivation is presumably caused by the change of interfacial properties, due to binding site occlusion upon complex coimmobilization formations. Our findings are generalized to any coimmobilization methodology for Nbs and, thus, for the construction of high-performance immuno-surfaces.Electronic Supplementary MaterialSupplementary material (experimental section, HER2 detection using anti-HER2-mAb-functionalized microcantilevers) is available in the online version of this article at 10.1007/s12274-021-3588-4.

Electrochemical characteristics of molten iron electrodes in slag and electrochemical properties of their interface

Kinetic characteristics of molten iron/slag reactions and interfacial properties between molten iron/slag are of profound importance in steelmaking but quantitative electrochemical descriptions are lacking. Therefore, a detailed electrochemical investigation of pure (carbon-free) molten iron in slag was performed in the present work, using mostly impedance spectroscopy. Measurements were made between 1600–1700 °C at the rest potential and also at direct current biases to elucidate changes in interfacial properties when metal/slag reactions take place. Various fundamental physiochemical properties were measured for the first time including exchange currents, standard heterogeneous rate constants, Nernst diffusion layer thicknesses in slag, differential capacitance curves, potentials of zero charge, excess charge density curves, and electrocapillary curves. Results and discussion inform about the electric double layer formed between molten iron and slag.

Effect of Hydrothermal Dehydration on the Slurry Ability of Lignite.

The high moisture content limits the large-scale utilization of lignite. Hydrothermal dehydration (HTD) has been confirmed as an effective method to improve the quality of lignite for further utilization. In this study, the effects of the changes in the lignite interface properties caused by the HTD modified final temperature on the slurry ability were investigated in the range of 160–200 °C. The results indicated that with the gradual rise of the HTD modified final temperature, the content of the carboxyl groups and phenolic hydroxyl groups on the surface of lignite decreased by 21.95 and 36.34%, respectively. In the meantime, the atomic ratio of oxygen/carbon, the content of equilibrium moisture, and the thickness of the hydrated film were reduced from 0.293, 14.63%, and 34.26 nm to 0.252, 9.43%, and 13.33 nm, respectively. Therefore, these changes of interfacial properties improved the slurry ability of lignite, with higher fixed-viscosity solid concentration, lower yield stress, increased pseudo-plasticity, and gradually decreased static stability of the prepared lignite coal water slurry. hydrothermal dehydration; slurry ability; oxygen-containing functional groups; hydrated film

In vitro digestion of emulsified lard-based diacylglycerols.

Diacylglycerols as a fat substitute in meat products is a growing area of interest. This study was conducted to analyze the digestion rate, digestion extent, and changes in interfacial properties of lard, glycerolized lard (GL), and purified GL (PGL) in an emulsions system by pH-stat in vitro digestion. PGL had significantly higher hydrolysis rate and final digestion extent than lard (P ≤ 0.05) during in vitro digestion. The analysis on diameter variations of lard, GL, and PGL during digestion indicated that the surface- and volume-weighted mean particle diameters of all samples had the same variation trend, but variation degree was different. Concurrently, the ζ-potential analysis of the lard, GL, and PGL during the digestion process showed that the absolute values of the ζ-potentials of the three types of lipids increased at first and subsequently decreased. The microstructure changes results for lard, GL, and PGL showed there was no obvious flocculation, and the particle size of lard throughout the digestion process was larger than that of GL and PGL. This study showed that lard-based diacylglycerols had high digestibility characteristics and could be applied as a functional lipid in meat products to improve human health. © 2020 Society of Chemical Industry.

Molecular Dynamics Study on the Effects of Metal Cations on Microscale Interfacial Properties of Oil–Water-Surfactant System

Water flooding is a secondary oil recovery process where oil from porous rocks is displaced by high-pressure water. Often, water with high salinity was used in this process. In this work, the effects of metal cations on interfacial properties of oil–water-surfactant flooding systems were investigated using molecular dynamics simulation. The results show that the addition of metal cations can cause a slight decrease of the interfacial thickness and the greatly enhanced interaction between the polar head group of surfactant and water molecules, which effectively restrain the water molecules nearby the polar head group. The diffusion coefficients of water molecules in oil–water-surfactant system decrease in the presence of the metal cations. The results of the interface information energy show that the addition of metal cations makes the oil–water-surfactant system more stable. The order parameter analysis showed that the surfactant molecules become more ordered in the normal direction of the interface. Our results demonstrated that the enhanced interaction between water molecules and surfactant head groups due to the existence of metal cations is the driving factor for the change of interfacial properties, especially the interfacial orientation of surfactants. In brief, the most important contribution of our work is the first demonstration of that the enhanced interaction between water molecules and surfactant head groups due to the existence of certain metal cations is the driving factor for the change of interfacial properties especially the interfacial orientation of surfactants. Our work should be valuable for the understanding of interfacial phenomenon of oil–water-surfactant systems and their industrial applications such as for oil displacement.

Construction of an ultrasensitive electrochemical sensing platform for microRNA-21 based on interface impedance spectroscopy

A hybridization chain reaction (HCR) amplification-based electrochemical impedimetric biosensor is fabricated for the quick, sensitive, and specific detection of miRNA-21 (miR-21) via monitoring of electrode interfacial property changes in real-time. Two sequences of H1 and H2 are adopted to trigger HCR amplification. A large amount of linear DNA concatemer are formed which could change the interfacial properties of the electrode. Interfacial charge transfer resistance difference (Rct) is probed via electrochemical impedance spectroscopy (EIS) and Randles equivalent circuit. After amplifying via HCR, oligonucleotides with negatively charged repelling [Fe(CN)6]3−/4− ions can form a spatial blockage. HCR amplification strategy markedly enhanced the electrochemical signal with a limit of detection (LOD) down to 4.63 fM (S/N = 3). This strategy exhibited excellent selectivity for three different miRNAs: miR-199a, miR-141, and miR-155. Moreover, results show that the proposed method can be applied to miR-21 detection in the total RNA extracted from five cells. This work presents an enzyme-free and label-free EIS nucleic acid sensor for sensitively and selectively detecting miR-21, offering a promising approach in early diseases diagnosis.

A model of grain boundary complexion transitions and grain growth in Yttria-doped alumina

In this work, we present a physically-parameterized microstructure evolution model for the Yttria-doped alumina system. Yttria-doped alumina is a well-known ceramic system which undergoes first-order phase-like transitions at grain boundaries, which can radically alter interface properties. The change in interfacial properties in turn can radically change microstructure outcomes during processing, including the induction of abnormal grain growth modes. In this work, we develop a simulation that evolves alumina microstructure as a function of yttria concentration and temperature. In the window studied, we achieve strong agreement with reviewed experimental results in identifying the windows for large grains, small grains, abnormal grain growth, and complexion transition kinetics (as measured by JMAK analysis). We then apply the model to study and demonstrate how the possible inclusion of second-phase particles or uneven solute distribution profiles will impact microstructure evolution. It is found that particles do not significantly affect abnormal grain growth in the window studied (but do lead to reduced grain size through pinning effects). It is found that even modest amounts of solute inhomogeneity will result in substantial changes in microstructure outcomes, frequently leading to clusters of abnormal grains. This model largely corroborates the expectations and hypotheses made from recent experimental studies in oxide-doped alumina systems. Further, it is found that there exists a peak transition fraction for the system at which abnormal grain size tends to be maximized.

Impact of Asphaltenes on Contact-Angle Variations and Surface Topography and Composition

Summary The asphaltene precipitation affects the rock/fluid interaction in a live-oil reservoir, which has a significant effect on oil recovery and flow in the production network. In this work, we examine the changes in interfacial properties (such as contact angle between the live-oil, brine, and quartz system) as well as surface topography and compositions caused by asphaltene precipitations that are related to pressure-depletion processes. The experimental method is based on the pendant-drop-shape method using a high-resolution camera for quantitative image analysis and a high-resolution digital-pressure transducer in a high-pressure high-temperature fluid cell. The contact angle with quartz was measured in the presence of deionized water as the surrounding medium at isothermal condition. The experiments were conducted in a pressure-depletion fashion, where pressure is decreased in steps capturing the asphaltene onset pressure (AOP). At each pressure stage, sufficient time was given to stabilize the contact angle. The transient experimental contact-angle data for a system containing a live oil, brine, and quartz is presented. In particular, we Show that the time of stabilization and contact angle decreases at sequential pressure steps, except near the vicinity of AOP where they have a sharp jump signifying the effect of asphaltene precipitation Use the solubility-parameter approach for asphaltene modeling to predict asphaltene precipitation from live oil at pressures between the saturation point and AOP Relate the amount of precipitation with change in interfacial properties, such as interfacial tension (IFT) and contact angle Use image-analysis techniques such as scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS) to analyze the topography and composition of the quartz surface after asphaltene deposition to supplement our observation Despite that asphaltene effects on wettability alteration have been proposed, this is the first experimental evidence that pressure-depletion-driven asphaltene precipitation alters the contact angle at realistic reservoir conditions (high-pressure high-temperature live oils). These data can be used as a basis to establish the benchmark data, model calibration for managing and preventing remediation asphaltene problems, and to design the proper facility and operating conditions for efficient recovery and operational processes.

Unexpected monolayer-to-bilayer transition of arylazopyrazole surfactants facilitates superior photo-control of fluid interfaces and colloids.

Interfaces that can change their chemistry on demand have huge potential for applications and are prerequisites for responsive or adaptive materials. We report on the performance of a newly designed n-butyl-arylazopyrazole butyl sulfonate (butyl-AAP-C4S) surfactant that can change its structure at the air-water interface by E/Z photo-isomerization in an unprecedented way. Large and reversible changes in surface tension (Δγ = 27 mN m-1) and surface excess (ΔΓ > 2.9 μmol m-2) demonstrate superior performance of the butyl-AAP-C4S amphiphile to that of existing ionic surfactants. Neutron reflectometry and vibrational sum-frequency generation spectroscopy reveal that these large changes are caused by an unexpected monolayer-to-bilayer transition. This exceptional behavior is further shown to have dramatic consequences at larger length scales as highlighted by applications like the light-triggered collapse of aqueous foam which is tuned from high (>1 h) to low (<10 min) stabilities and light-actuated particle motion via Marangoni flows.

A Model of Grain Boundary Complexion Transitions and Grain Growth in Yttria-Doped Alumina

In this work, we present a physically-parameterized microstructure evolution model for the Yttria-doped alumina system. Yttria-doped alumina is a well-known ceramic system which undergoes first-order phase-like transitions at grain boundaries, which can radically alter interface properties. The change in interfacial properties in turn can radically change microstructure outcomes during processing, including the induction of abnormal grain growth modes. In this work, we develop a simulation that evolves alumina microstructure as a function of yttria concentration and temperature. In the window studied, we achieve strong agreement with reviewed experimental results in identifying the windows for large grains, small grains, and abnormal grain growth. We then apply the model to study and demonstrate how the possible inclusion of second-phase particles or uneven solute distribution profiles will impact microstructure evolution. It is found that particles do not significantly affect abnormal grain growth in the window studied (but do lead to reduced grain size through pinning effects). It is found that even modest amounts of solute inhomogeneity will result in substantial changes in microstructure outcomes, frequently leading to clusters of abnormal grains. This model largely corroborates the expectations and hypotheses made from recent experimental studies in oxide-doped alumina systems.

Change in interfacial properties of milk fat globules by homogenization and thermal processing plays a key role in their in vitro gastrointestinal digestion

The effects of homogenization, homogenization plus thermal processing including high temperature short time (HHTST) or ultra-high temperature (HUHT) treatment on digestion and interfacial properties of milk fat globules during simulated gastrointestinal digestion were investigated. Compared to raw milk fat globules, homogenization and thermal processing increased the initial digestion rate of milk fat globules. Homogenization increased the release of middle- and long-chain fatty acids, HHTST increased the release of unsaturated fatty acids, and HUHT increased the release of all types of fatty acids under gastrointestinal digestion. After homogenization, milk proteins (caseins and whey proteins) increased but glycosylated molecules decreased, both of which were at the surface of milk fat globules. The amount of glycosylated molecules at the surface of HHTST milk fat globules and the amount of denatured milk proteins at the surface of HUHT milk fat globules were higher than those of homogenized milk fat globules. During gastrointestinal digestion, fat globules in HHTST milk possessed higher amount of glycosylated molecules and more integrated phospholipid layers, and HUHT milk fat globules had more filamentous phospholipid layers, and less integrated phospholipid layers and glycosylated molecules than those of homogenized milk fat globules. Therefore, the changes in composition and microstructure of glycosylated molecules and phospholipid layers at the surface of milk fat globules induced by homogenization and thermal processing might contribute to the digestion difference of milk fat globules.

Surfactant-assistant atmospheric acid leaching of laterite ore for the improvement of leaching efficiency of nickel and cobalt

Atmospheric acid leaching has attracted great attention from scientists due to the mild leaching conditions. However, the leaching efficiency of nickel is lower than that using high pressure acid leaching. Herein, we report the use of a surfactant (e.g., stearyltrimethyl ammonium chloride, STAC) to improve the leaching efficiency of Ni. The effects of surfactant type, ore-surfactant ratio, leaching temperature, and leaching duration on the leaching ratio of Ni were investigated. The use of STAC resulted in the high efficiency for Ni leaching at 100 °C with an ore-surfactant ratio of 15 and leaching duration of 8 h. The leaching efficiencies of Ni and Co were significantly higher than that of atmospheric acid leaching. The surface tension and viscosity of the leaching solution, and the zeta potential of the leached residue were analyzed to investigate the mechanism of the leaching process. The changes of interfacial properties improved ionic diffusion and decreased metal adsorption, which further lead to the increasing of leaching efficiency.

Tailoring engineered cementitious composite with emulsified asphalt for high damping

Cement asphalt (CA) mortar has been widely used as cushion layer between the concrete roadbed and track slab for vibration absorption in high-speed railways (HSR). However, premature cracking of CA has been recognized as a critical safety problem during HSR operation. There is a need for developing more durable materials with similar damping ability and vibration absorption characteristics as CA mortar. This paper reports the development of emulsified asphalt (EA) modified Engineered cementitious composite (EA-ECC) with favorable damping property, which may be used as vibration absorbing layer material. The mechanical properties, including compressive strength, tensile stress-strain relation and dynamic mechanical properties of EA-ECCs were investigated. It is found that the desirable higher loss modulus and loss factor are accompanied by lower compressive and tensile strength with increase of EA dosage. Conversely, the deformation capacity of EA-ECCs shows an opposite trend due to favorable change in interfacial properties. In addition, with increasing test temperature, the material also shows a trend similar to the addition of EA. Change of microstructures of EA-ECCs were also observed through scanning electron microscope (SEM) imaging. It is concluded that incorporating EA significantly improves the tensile ductility and energy dissipation ability of ECC materials. Increase of 210 times in tensile ductility and similar loss factor are demonstrated when compared with those of CA with similar EA dosage.

Argon plasma improves the tissue integration and angiogenesis of subcutaneous implants by modifying surface chemistry and topography.

BackgroundTissue integration and vessel formation are important criteria for the successful implantation of synthetic biomaterials for subcutaneous implantation.ObjectiveWe report the optimization of plasma surface modification (PSM) using argon (Ar), oxygen (O2) and nitrogen (N2) gases of a polyurethane polymer to enhance tissue integration and angiogenesis.MethodsThe scaffold’s bulk and surface characteristics were compared before and after PSM with either Ar, O2 and N2. The viability and adhesion of human dermal fibroblasts (HDFs) on the modified scaffolds were compared. The formation of extracellular matrix by the HDFs on the modified scaffolds was evaluated. Scaffolds were subcutaneously implanted in a mouse model for 3 months to analyze tissue integration, angiogenesis and capsule formation.ResultsSurface analysis demonstrated that interfacial modification (chemistry, topography and wettability) achieved by PSM is unique and varies according to the gas used. O2 plasma led to extensive changes in interfacial properties, whereas Ar treatment caused moderate changes. N2 plasma caused the least effect on surface chemistry of the polymer. PSM-treated scaffolds significantly (P<0.05) enhanced HDF activity and growth over 21 days. Among all three gases, Ar modification showed the highest protein adsorption. Ar-modified scaffolds also showed a significant upregulation of adhesion-related proteins (vinculin, focal adhesion kinase, talin and paxillin; P<0.05) and extracellular matrix marker genes (collagen type I, fibronectin, laminin and elastin) and deposition of associated proteins by the HDFs. Subcutaneous implantation after 3 months demonstrated the highest tissue integration and angiogenesis and the lowest capsule formation on Ar-modified scaffolds compared with O2- and N2-modified scaffolds.ConclusionPSM using Ar is a cost-effective and efficient method to improve the tissue integration and angiogenesis of subcutaneous implants.

Properties of novel bismaleimide resins and thermal ageing effects on the ILSS performance of their carbon fibre–bismaleimide composites

An oligomeric bismaleimide (BMI) containing both phthalide cardo and cyano group (PCBMI) was mixed with O,O'‐diallyl bisphenol A (DABPA). The thermal properties of PCBMI/DABPA in different proportions (1:0.87, 1:1, and 1:1.2) and their composites were characterized using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and dynamic mechanical analysis (DMA). In addition, the mechanical properties of the prepared composites were also investigated. The results exhibited excellent thermal stability, heat resistance, and mechanical properties. We further investigated the effects of thermal ageing at 200°C and 250°C in air for up to 1000 h on inter laminar shear strength (ILSS) of the carbon fiber–bismaleimide composites (T700/DPC87). Scanning electron microscopy (SEM) and scanning acoustic microscope (SAM) were employed to characterize interfacial property changes, and Fourier transform infrared (FTIR) was employed to characterize chemical changes due to ageing. The results indicated PCBMI/DABPA resin had an excellent interface bonding capacity and aging resistance. It can, therefore, be widely used in aeronautics and space industries. POLYM. COMPOS., 40:E1283–E1293, 2019. © 2018 Society of Plastics Engineers

Enhanced foaming and emulsifying properties of high-pressure-jet-processed skim milk

The effect of high pressure jet (HPJ) processing on foaming and emulsifying properties of skim milk was studied. Viscosity of milk significantly increased at HPJ processing pressures ≥300 MPa and particle size distribution became bimodal for milk processed at 400 or 500 MPa. Cryo-electron microscopy of milk processed at 400 or 500 MPa showed formation of non-uniform aggregates of proteins, which were distinctly larger than intact casein micelles. HPJ processing markedly increased the foam expansion index of milk. In addition, significant increases in foam volume stability index and emulsion activity index were observed for milk following HPJ processing at ≥300 MPa. It is suggested that the structural modifications occurring in the micelles due to HPJ processing are primarily responsible for the observed changes in interfacial properties. The ability to modify key functional properties of milk by HPJ processing opens opportunities for milk-based novel ingredient manufacturing.

A Capillary Flow Dynamics-Based Sensing Modality for Direct Environmental Pathogen Monitoring.

Toward ultra-simple and field-ready biosensors, we demonstrate a novel assay transducer mechanism based on interfacial property changes and capillary flow dynamics in antibody-conjugated submicron particle suspensions. Differential capillary flow is tunable, allowing pathogen quantification as a function of flow rate through a paper-based microfluidic device. Flow models based on interfacial and rheological properties indicate a significant relationship between the flow rate and the interfacial effects caused by target-particle aggregation. This mechanism is demonstrated for assays of Escherichia coli K12 in water samples and Zika virus (ZIKV) in blood serum. These assays achieved very low limits of detection compared with other demonstrated methods (1 log CFU/mL E. coli and 20 pg/mL ZIKV whole virus) with an operating time of 30 s, showing promise for environmental and health monitoring.