Effect Of Displacement Research Articles

Gravitational wave pulse and memory effects for hairy Kiselev black hole and its analogy with Bondi–Sachs formalism

The investigation of non-vacuum cosmological backgrounds containing black holes is greatly enhanced by the Kiselev solution. This solution plays a crucial role in understanding the properties of the background and its relationship with the features of the black hole. Consequently, the gravitational memory effects at large distances from the black hole offer a valuable means of obtaining information about the surrounding field parameter N and parameters related to the hair of the hairy Kiselev Black hole. This paper investigates the gravitational memory effects in the context of the Kiselev solution through two distinct approaches. At first, the gravitational memory effect at null infinity is explored by utilizing the Bondi–Sachs formalism by introducing a gravitational wave (GW) pulse to the solution. The resulting Bondi mass is then analyzed to gain further insight. Therefore, the Kiselev solution is being examined to determine the variations in Bondi mass caused by the pulse of GWs. The study of changes in Bondi mass is motivated by the fact that it is dynamic and time-dependent, and it measures mass on an asymptotically null slice or the densities of energy on celestial spheres. In the second approach, the investigation of displacement and velocity memory effects is undertaken in relation to the deviation of two neighboring geodesics and the deviation of their derivative influenced by surrounding field parameter N and the hair of hairy Kiselev black hole. This analysis is conducted within the context of a GW pulse present in the background of a hairy Kiselev black hole surrounded by a field parameter N.

Using Diverse Distribution Platforms to Support Young Children’s Coping Strategies in the Midst of Crisis and Conflict

ABSTRACT Evidence firmly establishes the link between early childhood interventions and the mitigation of the effects of adverse childhood experiences (ACEs). Given the long-term effects of conflict and displacement on children’s healthy development, educational mass media can offer critical learning opportunities to mitigate both the impact of learning disruption and the effects of ACEs. This paper will highlight three different ways media, and its diverse distribution platforms, can support young children’s understanding and use of coping strategies in the face of significant adversity. Using examples of diverse distribution to reach refugee and migrant children in the United States and across Latin America and the Middle East, this paper will highlight the ways media can support children and families affected by displacement and conflict to develop critical coping strategies. Lessons learned in developing and adapting coping strategies for diverse contexts and platforms include learnings for content curation and implementation, engagement of local and regional advisors, and importance of a network of on-the-ground implementing partners. These findings offer guidance for those developing content and programs for children in conflict and crisis, in particular creators of children’s media and outreach programs.

Long-term effects of job displacement on earnings and mental health: Evidence from population-wide administrative data

This paper analyzes the impacts of job displacement on earnings and mental health in Taiwan. Findings reveal an immediate 67%–68% earnings loss after displacement, with incomplete recovery after a decade. Mental health suffers in the long term, with 15%–16% more outpatient visits and 57%–62% higher medical costs.

Numerical analysis of an oscillating square and circular bluff body submerged in the wake of an identical static bluff body: A GPU Accelerated Immersed Boundary-Lattice Boltzmann Approach

Hydrodynamic forces acting on marine structures, tubes, and objects can trigger disruptive vibrations. This study is an effort to encapsulate the results of wake induced vibration among tandem bodies. Specifically, impact of a static upstream body on a downstream oscillating body at Reynolds number 100 and constant frequency ratio Fr=1.0. The effects of streamwise displacement are investigated in a tandem arrangement of 1.05≤Lx/D≤12.0. In this study an in-house developed code employed that combines an immersed boundary lattice Boltzmann method with a structural equation and is accelerated using a graphical processing unit. When comparing scenario 1 (both bodies oscillate) to scenario 2 (only the downstream body oscillates), the study finds that the upstream square body motion has little effect on the downstream square body oscillation. However, the upstream circular body motion significantly impacts the downstream body oscillation. In addition, the study observes that the maximum amplitude occurs after reaching the critical spacing in scenario 2, whereas it occurs at and after the critical spacing in scenario 1. The critical spacing ratio is similar in both scenarios but varies for square and circular bodies. Lastly, the study examines the flow physics and hydrodynamic force coefficients of the downstream oscillating body.

Domain of influence on generalized thermoelastic diffusion theory

The aim of this research work is to establish the theory of the domain of influence of diffusion disturbance with potential-temperature disturbance under the theory of generalized thermo-elastic diffusion using Lord and Shulman model. For a finite time t > 0, it has been proved that the potential due to displacement, temperature and diffusion effect does not produce any disturbances outside a bounded domain and the domain of influence is dependent on the support of thermo-elasto-diffusive load, the thermo-elasto-diffusive coupling constant and the phase-lag parameters. It has been shown that the domain of influence of the present case reduce to the domain of influence for classical thermo-elasticity theory with or without diffusion and the thermo-elasticity theory with one relaxation parameter without diffusion. Also, the effect of diffusion on thermal wave propagation is shown. This theorem will be applicable to analyze the deformation occur in elastic solids due to internal and external loads for the thermo-elasto-diffusive models and problems based on it in the field of engineering physics like solid-state-physics, physical metallurgy (fabrication of semi-conductor devices in mixture metals and molten semi-conductor), material engineering (separation of polymers), aircraft engineering, mechanical engineering and also in the industries like oil extraction from hydrocarbon and manipulation of macro-molecules like DNA etc.

Flooding Performance and Optimization of Injection Parameters of Nanosized Oil Displacement Agents in Extra-Low-Permeability Reservoirs.

There have been few studies on the role of nanofluids in oil displacement and injection parameters, despite their significant impact on the oil displacement effect. To enhance oil recovery in an ultralow-permeability reservoir, the nanosized oil-displacement agent with nano-SiO2 modified by a silane coupling agent as a main component was selected for the first time in the Changqing oilfield. To assess the performance of the nanofluid, various factors such as particle size, contact angle, interfacial tension, and emulsion stability were taken into consideration. The oil displacement effect of nanofluids was evaluated by a microscopic model and ultralow-permeability core displacement experiment, and its optimal injection parameters were determined. The average particle size of the nano-oil displacement agent is 22-30 nm. It can change the wetting condition of the rock from oil-wet to water-wet and reduce the oil-water interfacial tension. Even at 80 °C, the emulsion formed by the agent remained stable. The oil displacement experiment shows that the nano-oil displacement agent whose injection pressure increases can displace the residual oil trapped in small pores that cannot be affected by conventional water flooding. The injection mode of "nanoflooding agent drive + water drive + nanoflooding agent drive", injection rate of 0.1 mL/min, injection concentration of 0.5%, and injection volume of 0.5 PV (0.25 PV per segment), which can effectively guide the injection of the oil displacement agent, achieve the best oil displacement effect.

Copper Quantum Dot/Polyacrylamide Composite Nanospheres: Spreading on Quartz Flake Surfaces and Displacing Crude Oil in Microchannel Chips.

Polyacrylamide, silica, and other nanoparticles have all been realized in the field of enhanced oil recovery. Researchers often explore the mechanisms of spreading behavior and simulated displacement to develop more efficient types of nanoparticles. In this study, copper quantum dots were introduced into a acrylamide copolymerization system to obtain composite nanospheres and its structure, topographic, and application performance were characterized. The results show that the composite nanospheres have a particle size of around 25 nm, are uniformly loaded with copper particles, and have good temperature resistance. The spreading ability on the quartz flake surfaces and displacement effect in microchannels of composite nanospheres, acrylamide copolymer nanospheres, and copper quantum dots were compared by nanofluid spreading experiments and microchannel chip oil displacement experiments. The results indicate that the composite nanospheres can effectively reduce the water contact angle, promote the spreading of aqueous phase, and accelerate the oil droplet removal process; the accelerating effect is stronger than other samples. Its oil displacement effect is also the strongest, and it is minimized by the influence of channel size, temperature, and dispersing medium, with better stratigraphic adaptability. This work supports the practical application of copper quantum dot/polyacrylamide composite nanospheres in the oilfield.

Investigation on the Mechanical Characteristics of the Excavation of a Double-Line Highway Tunnel Underpass Existing Railway Tunnel under the Influence of Dynamic and Static Load

Research on the excavation mechanical properties of underpass tunnels has already had certain results, but only a few of them consider the effects of dynamic and static loads on the excavation mechanical properties of underground tunnels at the same time; particularly, there is a lack of research investigating double-line highway tunnels with angled underpasses of existing railway tunnels. In this paper, based on the tunnel project of the new double-line Shiqian Highway Tunnel passing under the Hurong Railway with an oblique angle, based on the method of over-advance geological prediction and investigations into the palm face surrounding the rock, the rock degradation caused by dynamic and static loads is quantified using the perturbation system. Additionally, the mechanical parameters of the rock under the influence of dynamic and static load coupling in the influence area of the cross-tunneling project are determined using the Hoek–Brown criterion, and the mechanical characteristics of the excavation of a tunnel under the double-lane highway tunnel passing under the existing railroad are constructed with the mechanical characteristics of the double-lane highway tunnel, taking into consideration the influence of the dynamic and static load coupling in a three-dimensional model. The results show that, in line with the new tunnel rock movement law for the top of the arch sinking, the bottom plate bulging, the side wall outward movement, the height and width of the arch, and the bottom plate arch show an increase with the tunnel excavation, while the side wall rock displacement effect is smaller; the left and right line tunnel disturbed area of the rule of change is similar; the existing tunnel bottom plate displacement is larger than the top plate and the left and right side wall, under the influence of the excavation time step. Typical profile point displacement is mainly determined by the distance from the excavation surface; von Mises stress extremes are observed in the top plate and side walls of the existing tunnel, which occur in the tunnel structure, and there are unloading and pressure-bearing zones in the bottom plate; the new tunnel has the same rock disturbance angle under the four calculation conditions and, based on the displacement control criterion, the excavation method is preferred and the upper and lower step blasting excavation method is recommended.

The Impact of Rotor Axial Displacement Variation on Simulation Accuracy of Fully Magnetic Levitation Centrifugal Blood Pump.

The rotor axial displacement of the full magnetic levitation blood pump varies with the operating conditions. The effect of rotor axial displacement on simulation results is unclear. This study aimed to evaluate the effect of rotor axial displacement on the predicted blood pump flow field, hydraulic performance, and hemocompatibility through simulation. This study used the CentriMag blood pump as a model, and conducted computational fluid dynamics simulations to assess the impact of rotor displacement. Considering rotor axial displacement leads to opposite results regarding predicted residence time and thrombotic risk compared with not considering rotor axial displacement. Not considering rotor axial displacement leads to deviations in the predicted values, where the effects on the flow field within the blood pump, ratio of secondary flow, and amount of shear stress >150 Pa are significant. The variation in the back clearance of the blood pump caused by the ideal and actual rotor displacements is the main cause of the above phenomena. Given that the rotor axial displacement significantly impacts the simulation accuracy, the effect of rotor axial displacement must be considered in the simulation.

Design and Characteristic Research on Variable Displacement Mechanism of Two-Dimensional (2D) Bivariable Pump

In a hydraulic system, a micro variable pump is required to be high pressure and high speed, and this work presents a new type of 2D bivariable pump structure in which the worm gear and worm mechanism are used to rotate the cylinder block to change the flow distribution state of the cylinder window and the piston groove to change the displacement of the 2D pump. The flow–pressure mathematical model of the 2D variable pump is established to analyze the relationship between pump displacement and the pump cylinder rotation angle and the effects of variable displacement on pump pressure characteristics, flow characteristics, and volume efficiency in Matlab. During the experiment, we tested the change in the corresponding pump output flow when the cylinder rotation angle is 0~12°, which verifies the correctness of the variable calculation model. The experimental results indicate that the volume efficiency and mechanical efficiency of the single-piston 2D pump are reduced to different degrees after variable displacement, the volume efficiency is reduced by approximately 3% at most, and the mechanical efficiency is reduced by approximately 5% at most.

Lateral attitude change: displacement effects as a reaction to blatant social influence

According to the lateral attitude change (LAC) model, lateral (i.e., indirect) attitude change may occur in the absence of focal (i.e., direct) attitude change. To examine such displacement effects, we asked 124 participants to assume a teacher’s role and grade two moderately good essays. They graded the first essay once before and once after they learned the (very good vs. very poor) grade the essay had allegedly received by a professor. Given that the professor’s grade represented a blatant, disproportionate influence attempt, we hypothesized focal resistance (i.e., no attitude change toward the first essay) but a displacement effect (i.e., attitude change toward the second essay). Instead of displacement, results indicated generalization (focal and lateral effects). However, among participants who had resisted the influence attempt (n = 65), a displacement pattern was observed. Implications for the LAC model are discussed.

The Effect of First Metatarsal Shortening and Sagittal Displacement on Forefoot Pressure in MIS Hallux Valgus Correction

Introduction/Purpose: Minimally invasive surgical (MIS) treatment of hallux valgus (HV) deformity is increasing in popularity. A 2mm-diameter burr is used to create a distal first metatarsal osteotomy prior to capital fragment translation and fixation. The metatarsal will shorten by the burr’s diameter (2mm). Plantar or dorsal capital fragment displacement may also cause load transference and possibly transfer metatarsalgia. In this study, we examine the effect of MIS HV on forefoot loading mechanics with respect to metatarsal shortening and sagittal plane displacement. Methods: Four lower-limb cadaveric specimens were studied. A pedobarography pressure-sensing mat was used to record forefoot plantar pressure in a controlled weightbearing stance position.10 Control and post-osteotomy measurements were obtained with the capital fragment fixated in 3 possible positions: 0mm, 5mm dorsal, and 5mm plantar displacement. Pedobarography data yielded pressure data within measurable graphical depictions. Raw mean contact pressure measurements were taken under the first and fifth metatarsal heads to establish medial and lateral forefoot loading pressure ratios. A priori power analysis was performed based on previous peer-reviewed pedobarographic data and our study was adequately powered. Results: 40 measurements were recorded and ratios of medial-to-lateral forefoot loading were constructed. Medial forefoot pressure change control versus 0mm displacement, and control versus dorsal displacement was not found to be statistically significant (p=0.525, p=0.55 respectively). Significant medial pressure increase was identified comparing control versus plantar displacement (p=0.006). Lateral pressure increased significantly with dorsal displacement of the osteotomy (p=0.013). Conclusion: MIS hallux valgus correction does not appear to cause increase in lateral forefoot pressure loading when sagittal plane displacements are controlled. Plantar displacement increases medial loading, and dorsal displacement increases lateral loading. The clinician must consider metatarsal head position post-osteotomy, as decrease in medial loading and subsequent increase in lateral loading may lead to lateral forefoot pain and transfer metatarsalgia.

169 Quantifying the Effect of Fracture Morphology on Nonunion for Traumatic, Isolated Odontoid Fractures Managed Nonoperatively: A Propensity Score Matched Analysis

INTRODUCTION: Odontoid fractures disproportionately affect older patients who have high surgical risk, but also high rates of fracture nonunion. METHODS: We examined all patients with isolated odontoid fractures treated nonoperatively at our institution between 2010 and 2020. Multivariable regression and propensity score matching were used to quantify the effect of fracture type, angulation, comminution, and displacement on bony healing by 26 weeks from injury. RESULTS: 303 consecutive traumatic odontoid fracture patients were identified, of whom 163 (53.8%) had isolated fractures that were managed nonoperatively. Selection for nonoperative management was more likely with older age (OR = 1.45 [1.14, 1.84], p = 0.003), and less likely with angulated fractures (OR = 0.31 [0.14, 0.65], p = 0.002), or higher presenting Nurick scores (OR = 0.78 [0.63, 0.97], p = 0.023). Factors associated with nonunion at 26 weeks were angulated morphology (OR = 16.14 [2.93, 89.00], p = 0.001) and Anderson-D’Alonzo Type II morphology (OR = 6.54 [2.16, 19.77], p = 0.001). Cox proportional hazards regression demonstrated slower healing time for angulated (HR 0.144 [0.044, 0.377], p = 0.0003) and type II fractures (HR = 0.380 [0.214, 0.673], p = 0.0009). Propensity score matching to assess the effect of type II fracture, fracture angulation, displacement, and comminution all yielded balanced models (Rubin's B < 25.0, 0.5 < Rubin's R < 2.0). By 26 weeks, controlling for confounders, 77.3% of type I or III fractures healed, compared to 38.3% of type II fractures (p = 0.001), and 56.3% of non-angulated fractures healed compared to 12.5% of angulated fractures (p = 0.015). Fracture displacement and comminution had no significant effect. CONCLUSIONS: Type II fracture morphology and fracture angulation significantly increase nonunion among nonoperatively managed isolated traumatic odontoid fractures, but fracture comminution and displacement do not.

Gravitational memory effects of black bounces and a traversable wormhole

Black bounces are spacetimes that can be interpreted as either black holes or wormholes depending on specific parameters. In this study, we examine the Simpson–Visser and Bardeen-type solutions as black bounces and investigate the gravitational wave in the background of these solutions. We then explore the displacement and velocity memory effects by analyzing the deviation of two neighboring geodesics and their derivatives influenced by the magnetic charge parameter a. This investigation aims to trace the magnetic charge in the gravitational memory effect. Additionally, we consider another family of traversable wormhole solutions obtained from non-exotic matter sources to trace the electric charge Qe\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$Q_{e}$$\\end{document} in the gravitational memory effect, which can be determined from the far field asymptotic. Furthermore, this research aims to explore the gravitational memory effect related to the variation in Bondi mass for the Simpson–Visser and Bardeen-type black bounces. The investigation will also be conducted on a traversable wormhole solution that does not require any exotic field. This study holds importance in not only identifying compact objects such as wormholes through gravitational memory effects but also in observing the charge Qe\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$Q_{e}$$\\end{document}, which offers a tangible manifestation of Wheeler’s idea of “electric charge without charge.”

Creating inequality in access to public transit? Densification, gentrification, and displacement

Densification is a key concept in contemporary urban planning. Yet, there are widespread concerns about densification causing displacement and gentrification. This paper examines densification around train stations—a prevalent form of transit-oriented development (TOD) in cities with established public transit systems—in the Canton of Zurich, Switzerland. We assess the effects of densification around train stations on the socioeconomic population composition in these areas and investigate three different potential displacement effects. Leveraging 1.8 million linked person-housing unit observations for all individuals within our study perimeter, we provide a more nuanced understanding of densification’s effects on the population composition and displacement than prior research. Our findings reveal that even though densification increases the absolute number of low-income residents, it primarily benefits middle- and high-income households. Specifically, there is a decline in the share of low-income residents, attributed to the influx of younger high-income individuals. Moreover, incumbent low-income residents experience an increased risk of direct displacement due to housing demolitions. These outcomes highlight the limitations of TOD strategies in mitigating persistent socioeconomic disparities in public transit access, emphasizing the need for more comprehensive measures to address the challenges of equitable housing and public transit accessibility.

Opening the black box of the use phase in circular economy life cycle assessments: Environmental performance of shell jacket reuse

AbstractLife cycle assessment (LCA) is highly needed and widely used to assess the environmental performance of circular economy (CE) measures such as reusing and sharing. However, the results of such LCAs are hampered by limited knowledge about the use phase of consumer products and oversimplification of important use phase aspects such as product functionality, user behavior, displacement, and rebound effects. This paper aims to validate the usefulness of a framework designed to assist practitioners in the generation and utilization of such knowledge in LCAs of circular measures. To validate the framework, a case study is used: reuse of shell jackets enabled by “premium secondhand” stores for outdoor equipment and clothing. The paper demonstrates that conclusions about the environmental performance of reuse can easily be altered depending on the functional unit definition, whether real user behavior data are used, and whether imperfect displacement and rebound effects are considered. For instance, shell jacket life cycles that include reuse and thus may be labeled “circular” have significantly higher environmental impact per use occasion than “linear” ones (used by one principal user the entire lifespan), since “circular” shell jackets are used less frequently, in particular during their first use span. Through facilitating the generation and utilization of environmentally relevant use phase data, which are otherwise often overlooked, the framework seems capable of supporting a better understanding of the environmental performance of CE measures.

Study on the Alkali-Free Three-Component Flooding System in the Daqing Oilfield.

ASP flooding is an important method to further improve oil recovery by a large margin. At present, it has entered the stage of industrial application, but there are still problems of scaling in the injection production system and high production maintenance costs. Based on the industrialized mature technology of weak alkali ASP flooding, sodium chloride is used to replace sodium carbonate, and the alkali-free three-component flooding (TC) system in the Daqing Oilfield is developed by mixing with petroleum sulfonate and partially hydrolyzed polyacrylamide. Based on the experiments of viscosity increasing, interface performance, stability, adsorption, and oil displacement effect, the differences between the alkali-free TC system and the weak alkali ASP system are compared and analyzed. The laboratory research results show that both systems are basically the same in terms of viscosity, viscoelasticity, shear resistance, interfacial activity, stability, and flowability. Due to the lack of alkaline water, the adsorption, emulsification, and oil displacement performance of the alkali-free TC system is slightly lower than that of the weak alkali ASP system. The recovery factor of core flooding can be increased by 27.31% over water flooding, which is 2.56 percentage points lower than that of the weak alkali ASP system. On the premise of the same 1% EOR effect, the agent cost of the alkali-free system is 17.02% lower than that of the alkali ASP system. This article innovatively verifies the feasibility of using NaCl instead of Na2CO3 and explains the mechanism of significantly improving oil recovery in composite systems under alkali-free conditions from the ion level. However, the emulsification effect of the alkali-free TC system is relatively weak. The next step of research would be to consider adding an E-surfactant to enhance the emulsification performance of the composite system. By improving the system composition, technical references are provided for the efficient development of other terrestrial sandstone oilfields.

Red box, green box: A self-report behavioral frequency measurement approach for behavioral addictions research.

Behavior frequency measures in behavioral addictions research fail to account for how engagement in the activity relates to each respondent's personal circumstances. We propose a "Red Box, Green Box" method, an alternative to conventional self-report behavior questions. Participants report two distinct time-based values: (1) Green box: time spent engaged in the activity during 'free' time, and (2) Red box: engagement in the activity at times when the respondent should be doing something else (e.g., studying, working, sleeping, exercising, etc.). Some practical examples of the 'red box, green box' method are provided. This method may help to calibrate behavioral frequency for each respondent and yield clearer insights into displacement effects and risks associated with frequency of use. We suggest some future research directions to test the feasibility and utility of this approach in different implementations.

Non-invasive Thermohydrodynamic Approach for Fast Cell Manipulation at the Microscale

Thermal gradients have emerged as a promising technique for manipulating and sorting biological material at the microscale, holding considerable potential in lab-on-a-chip technology. Herein, we propose a non-invasive thermohydrodynamic approach for fast cell manipulation using a microfluidic open-to-air device. Cell discrimination is achieved by simply changing the temperature gradient toward the control of the convective effect on their displacement. First, the size and morphology/roughness-based motion capabilities were modeled using polystyrene (PS) microparticles with different sizes (5 and 20 μm) and polycaprolactone (PCL) microspheres, respectively. Computational fluid dynamics simulations of the generated flow were also carried out to demonstrate the influence of both the thermohydrodynamic and Marangoni effects in the PS particle displacement, where the thermally induced convective effect was not enough to move the microparticles inside the channel, but the combination of thermally induced convection together with the Marangoni effect. Indeed, small particles (5 μm) followed a full convective path, whereas the bigger ones (20 μm) exhibited a rolling motion on the substrate from the cold side to the hot side. Also, the relationship between in-flow speed and PCL (≈ 20 μm) surface roughness confirmed the driving force of this convection-based approach. Then, the microfluidic device was successfully used to separate Henrietta Lacks cancer cells (HeLa) from red blood (RBCs) and fibroblast (HFF-1) cells. To this end, thermal gradients were tailored to achieve the desired thermohydrodynamic effect, showing a highly versatile performance. Both cell models (HeLa-RBCs and HeLa-HFF-1), due to rationale tweaking of the imposed temperature gradients (ΔT = 10 K, 303–293 K, and ΔT = 5 K, 303–298 K), were efficiently separated in less than 5 and 60 s, respectively; with excellent cell viabilities. The proposed microfluidic approach holds considerable promise for thermohydrodynamic sorting and manipulation of biological material by non-invasive methods using portable instrumentation. The potential parallelization of the thermal-convective approach opens new avenues for early disease diagnosis (liquid biopsies) or the study of biological systems, even at physiological temperatures with a potential impact in cell (organ)-on-a-chip technologies.

Molecular dynamics simulation on asphalt-limestone interfaces considering unconstraint surfaces and individual colloid components

In molecular dynamics (MD) simulation, interactions of asphalt-limestone interfaces are investigated inaccurately because applying of constraint aggregate surfaces simplify some kinetic energies. Utilizing unconstrained aggregate surfaces provides a novel insight to understand the intermolecular effect of displacement of unconstrained particles. The influence of mineral structures containing Mg2+ other than calcite on adhesion are also ignored. This study builds various unconstraint surfaces and individual colloid components to reasonably evaluate adhesion and interaction by calculating energy, diffusion, and distribution of asphalt-limestone interfaces. Simulations reveal that asphalt-limestone interactions intensify with aging and higher temperatures. Polarity, primarily from sulfoxide (SO) and carbonyl (CO) groups after aging, amplifies adhesion by enhancing electrostatic forces. Individual SARA (saturate, aromatic, resin, asphaltene) components exhibit higher interaction energies with limestone, and differences in interaction energies of SARA on limestone surfaces cause separation in asphalt. Ca2+ and Mg2+ mainly combine with CO32- ions via ionic binding, forming stable surfaces unaffected by asphalt. The mineral composition has a limited impact on asphalt-limestone interfaces, although magnesite displaying the highest attraction to asphalt due to greater electronegativity of Mg2+. Inside asphalt molecules, polar CO and SO groups and planar sharps exhibit strong attraction to aromatic rings, increasing intermolecular energies and cohesion. Self-agglomeration and stacking of asphaltenes, driven by π-π conjunctions in central-aromatic rings and reinforced by aging.