Increase In Collision Frequency Research Articles

Absorption of electromagnetic waves by cylindrical surface plasmon resonance

Abstract The absorption characteristics of cylindrical surface plasmon resonance (CSPR) have been studied. We demonstrated that a single plasma column with CSPRs can achieve high absorptivity at the plasmon frequency. We also studied the effects of plasma density and collision frequency on the absorptivity. As both of them increase, the corresponding absorptivity tends to increase first and then decrease, but with different reasons. Such manifestation is explained by analyzing transmission and reflection spectra in both cases, as well as magnetic field distribution patterns at the frequency of plasmon. On the one hand, the increase in plasma density leads to the enhancement of plasmons, improving transmittance; On the other hand, the increase in collision frequency leads to a weakening of plasmons and an increase in reflectivity. Finally, we investigated the absorption characteristics of plasmons in the plasma photonic crystals (PPCs) structure and overcame the absorption attenuation caused by the increase in plasma density by increasing the number of plasma columns. Meanwhile, the absorption generated by surface plasmon resonance is not affected by the lattice constant of PPCs. The research has shown that efficient absorption can be achieved using CSPR, resulting in extremely high absorptivity when using fewer plasma columns. Finally, we verified the absorption ability of CSPRs through experiments.

Contact electrification characteristics of solid oxygen particle-laden flows in liquid hydrogen transportation

The issue of electrostatic safety in liquid hydrogen systems has garnered increasing attention, especially concerning the potential threat of electrostatic explosions due to the collision-electrification phenomenon of solid oxygen particles formed after air leakage in liquid hydrogen pipelines. To delve into the contact electrification characteristics of solid oxygen particle-laden flows in liquid hydrogen transportation, a mathematical model based on the computational fluid dynamics-discrete element method (CFD-DEM) two-phase flow dynamics has been developed. This model integrates the Hertz contact theory for describing particle collision processes and the condenser model for describing particle collision-electrification. The reliability of this model has been validated in existing literature through its ability to capture the flow characteristics of two-phase flow and the electrification characteristics of particle groups. Using density functional theory to compute the solid oxygen work function and considering the low-temperature properties of liquid hydrogen, a series of numerical studies on the flow sedimentation and electrification characteristics of solid oxygen particle-laden flows in liquid hydrogen pipelines have been conducted. The results indicate that particles carry negative charges after colliding with stainless steel pipe walls, with single charge exchange magnitudes of approximately 10−12C for particle-wall continuous collision processes and 10−14C for particle-particle collision processes, resulting in particle charge-to-mass ratios on the order of tens of μC/kg at the outlet interface. The impact of electrostatic forces on particle motion is significant and cannot be overlooked. Furthermore, the effects of velocity, particle diameter, and pipe diameter on particle charge characteristics have been thoroughly analyzed. At low flow velocities, severe particle settlement occurs, leading to increased collision frequency between particles and walls and significant charge accumulation. Increasing flow velocity can mitigate particle settlement and reduce charge levels. Changes in particle and pipe diameters have a minor impact on particle settlement but can increase single charge amounts with larger particle diameters and intensify particle charging with reduced pipe diameters due to shortened radial travel distances, leading to increased collision frequency. Our study meticulously illustrates the charge characteristics of individual particles and particle groups, providing a theoretical basis for assessing the electrostatic safety of liquid hydrogen transportation systems under extreme conditions.

Enhancing low-concentration cell detection in single entity electrochemical systems through forced convection

This study advances the detection of bacteria at low concentrations in single-entity electrochemistry (SEE) systems by integrating forced convection. Our results show that forced convection significantly improves the mass transfer rate of electrolyte, with the mass transfer coefficient demonstrating a proportional relationship to the flow rate to the power of 1.37. Notably, while the collision frequency of E. coli initially increases with the flow rate, a subsequent decrease is observed at higher rates. This pattern is attributed to the mechanics of cell collision under forced convection. Specifically, while forced convection propels cells towards the ultra-microelectrode (UME), it does not aid in their penetration through the boundary layer, leading to cells being driven away from the UME at higher flow rates. This hypothesis is supported by the statistical analysis of collision data, including signal heights and rise times. By optimizing the flow rate to 2 mL/min, we achieved enhanced detection of E. coli in concentrations ranging from 0.9 × 107 to 5.0 × 107 cells/mL. This approach significantly increased collision frequency by elevating the mass transfer of cells, with the mass transfer coefficient rising from 0.1 × 10−5 m/s to 0.9 × 10−5 m/s. It provides a viable solution to the challenges of detecting bacteria at low concentrations in SEE systems.

Thermal transport properties of gas-filled silica aerogels.

Silica aerogel (SA), recognized as an efficient insulating material, is characterized by its extremely low thermal conductivity (TC) and high porosity, presenting extensive application potential in aerospace and building energy conservation. In this study, the thermal transport properties of gas-filled SA are explored using molecular dynamics (MD) methods. It is found that an increase in porosity leads to a significant decrease in TC, primarily due to enhanced phonon scattering and reduced material stiffness. Additionally, the TC of SA influenced by gas exhibits a pattern of initial decrease, followed by an increase, and then a decrease again, driven by complex interactions between gas molecules and pore walls, phonon localization, and scattering mechanisms. At a gas concentration of 80%, the TC in confined spaces is significantly increased by nitrogen, attributed to enhanced intermolecular interactions and increased collision frequency. The impact of gases on the TC of gas-solid coupled composite materials is also investigated, revealing that gas molecules serve as a "bridge" for phonons, playing a crucial role in reducing interfacial scattering and enhancing low-frequency vibrational modes, thus further enhancing heat transfer efficiency. The TC of these composite materials is primarily regulated by the gas-phase TC in response to temperature, while the response to strain is predominantly governed by variations in the solid-phase TC. These results provide essential theoretical support and design guidelines for the development and design of new high-efficiency insulating materials.

Research on wear characteristics of U-shaped elbows based on CFD-DEM coupling

The C++ programming language is employed to improve the Computational Fluid Dynamics (CFD)- Discrete Element Method (DEM) coupling interface in this paper, the accuracy of solid-liquid two-phase flow numerical model are validated through experiments. Subsequently, the wear characteristics of the U-shaped elbows under different elbows spacing, bending diameter ratio, particle volume concentration, and particle size are investigated. The research results indicate that as the spacing between bends is increased, the phenomenon of particle sedimentation is intensified, and the maximum collision angle in elbow 2 is increased. The location of the maximum collision angle is closer to the outlet of elbow 2. However, both the collision frequency and wear rate are reduced due to the decrease in the number of particles. Smoother particle flow and a reduction in the collision angle and wear rate of particles on both bends are achieved by increasing the bend ratio. During the variation of the particle volume fraction from 0.5% to 7%, the increase in collision frequency and wear rate of both bends is slowed down. A greater decrease is observed in elbow 2, but the “shielding effect” is not observed. Furthermore, at low volume fractions, kinetic energy is lost by particles as they flow through elbow 1, resulting in a lower average wear rate in elbow 2 compared to elbow 1. Conversely, at high volume fractions, the opposite effect occurs. Finally, when keeping the particle volume fraction constant, an increase in the particle size leads to a smaller wear area in both bends. The wear rate in elbow 1 increases at a slower rate, while the wear rate in elbow 2 exhibits an initial increase followed by a decrease trend.

The effect of external heat flux on the phase change materials composed of two phase water/PCM-graphene nanofluid in a copper nanochannel

The use of phase change materials (PCMs) is one of the modern and efficient technologies for thermal energy storage. PCMs are materials used for heat storage (without a noticeable temperature change) due to their high melting heat. In the upcoming research, the effects of external heat flux on the thermal behavior of water/PCM-graphene nanoparticles nanofluid in the presence of a copper nanochannel have been evaluated. Using a numerical simulation of molecular dynamics, various parameters of velocity (Vel) and temperature profiles, and thermal conductivity have been determined. The results reveal that with increasing heat flux from 0.1 to 0.5 W/m2, the maximum temperature of nanofluid increases from 369.21 to 384.29 K. So, as this external heat flux increases, more heat is being applied to the nanofluids, leading to an increase in their temperature. Therefore, the maximum temperature of the nanofluids in the nanochannel also increases. When an external heat flux is applied to a nanofluid, the temperature gradient across the fluid increases. This increased collision frequency results in a more efficient heat transfer between the NP and the base fluid, increasing thermal conductivity.

Kinetics of size change in air bubble and fat globule during ice cream freezing process

AbstractUsing a batch‐type freezer, this study investigated the influence of agitation speed on the time course change in the size of air bubbles and fat globules to establish kinetics of those during freezing. Higher agitation is advantageous not only for mixing enhancement but also for preventing local freezing and undesirable solidification, according to the results of flow visualization and time‐course change in the Reynolds number during freezing. Air bubbles and fat globule size were measured using samples obtained during freezing. For each agitations speed, the time‐course change in air bubble size was clearly different. Because of significant shear force, a smooth reduction in air bubble size was observed at a relatively high agitation speed. However, at the later stage of freezing, the increased collision frequency of the bubbles induced an undesirable increase in size. Aggregation of fat globules occurred immediately after the aqueous phase begin to be frozen. In addition, a greater agitation speed improved fat destabilization and hence increased the degree of aggregation (DA) as measured by the fat globule size distribution. At all agitation speeds, a decrease in DA was observed after a temporary increase in DA. This decrease can be explained by the breakup of the aggregates. At higher agitation speed, more serious decrease in DA was found. It was found that agitation speed significantly affects the kinetics of air bubbles and fat globules during freezing.Practical ApplicationsAfter freezing, air bubbles and fat globules size are important factors in determining ice cream quality. Nevertheless, no time‐course change in size has been constructed from the perspective of kinetics. To the best of our knowledge, this is the first study to investigate the effects of agitation speed on the time‐course change in air bubbles and fat globules size. The kinetics of air bubbles and fat globules are important in determining process parameters such as freezing time and agitation speed in the process design of freezers for ice cream manufacturing. Although this study was conducted using a bath‐type freezer, the kinetics of size change can be applied to process design with a continuous‐type freezer.

Influence of matching network and frequency on the effective quality factor and performance of a miniature radio frequency ion thruster

The radio frequency ion thruster (RIT) is an electric propulsion device that utilizes radio frequency (RF) power to ionize propellants; thus, its performance is influenced by the frequency and matching network of the RF. In this study, an L&T type wide-range matching network was employed to experimentally investigate the performance of a miniature RIT with 4 cm diameter at different frequencies. The experimental results show that changing the matching parameters of the L&T network at the same frequency leads to changes in the effective quality factor and varying performances of the thruster; under similar effective quality factors, changing the frequency does not significantly affect the performance of the thruster; however, the plasma resistance exhibits frequency dependence. As the frequency increases, the effective collision frequency increases, leading to an increase in plasma resistance, which is beneficial for improving the performance of the thruster at high frequencies. Finally, a set of methods for quickly comparing the performance of RITs was summarized based on the effective quality factor. These research results are also instructive for improving the ionization of induction-coupled discharge devices of other sizes.

The Role of Ion Rotation in Ion Mobility: Ultrahigh-Precision Prediction of Ion Mobility Dependence on Ion Mass Distribution and Translational to Rotational Energy Transfer.

The role of ion rotation in determining ion mobilities is explored using the subtle gas phase ion mobility shifts based on differences in ion mass distributions between isotopomer ions that have been observed with ion mobility spectrometry (IMS) measurements. These mobility shifts become apparent for IMS resolving powers on the order of ∼1500 where relative mobilities (or alternatively momentum transfer collision cross sections; Ω) can be measured with a precision of ∼10 ppm. The isotopomer ions have identical structures and masses, differing only in their internal mass distributions, and their Ω differences cannot be predicted by widely used computational approaches, which ignore the dependence of Ω on the ion's rotational properties. Here, we investigate the rotational dependence of Ω, which includes changes to its collision frequency due to thermal rotation as well as the coupling of translational to rotational energy transfer. We show that differences in rotational energy transfer during ion-molecule collisions provide the major contribution to isotopomer ion separations, with only a minor contribution due to an increase in collision frequency due to ion rotation. Modeling including these factors allowed for differences in Ω to be calculated that precisely mirror the experimental separations. These findings also highlight the promise of pairing high-resolution IMS measurements with theory and computation for improved elucidation of subtle structural differences between ions.

Hydrodynamic clogging of micro-particles in planar channels under electrostatic forces

Hydrodynamic clogging in planar channels is studied via direct numerical simulation for the first time, utilising a novel numerical test cell and stochastic methodology with special focus on the influence of electrostatic forces. Electrostatic physics is incorporated into an existing coupled lattice Boltzmann-discrete element method framework, which is verified rigorously. First, the dynamics of the problem is governed by the Stokes number, $St$ . At low $St$ , the clogging probability, $P$ , increases with $St$ due to increasing collision frequency. At high $St$ , however, $P$ decreases with $St$ due to quadratic scaling of hydrodynamic force acting on arches. Under electrostatic forces, clogging is well represented by the wall adhesion number, $Ad_w$ . For $Ad_w \lesssim 4$ , the mechanical dependence on $St$ is exhibited, while for $4 < Ad_w < 20$ , there is a transition to high $P$ as sliding along, and attachment to, the channel surface occurs increasingly. For $Ad_w \gtrsim 20$ , clogging occurs with $P > 0.95$ . Particle agglomeration, however, can also decrease $P$ due to diminished interaction with channel walls. Distinct parametric regions of clogging are also observed in relation to the channel width, while a critical width $w/d^*=2.6$ is reported, which increases to $w/d^*=4$ with strong electrostatic surface attachment. The number of particles that form stable arches across a planar channel is determined to be $n=\left \lceil {w/d}\right \rceil + 1$ . Finally, sensitivity to the Coulomb friction coefficient is determined in favour of calibrating numerical parameters to bulk system behaviour. The greatest sensitivities occur in situations where the arch stability is lowest, while clogging becomes independent of friction for strong wall adhesion.

Dynamic analysis and wear calculation of space deployable mechanism considering spherical joints with clearance and coating

In the space deployable mechanism considering spherical joints with clearance, the kinematic stability and working life of will be seriously affected. To address this problem, this paper proposes a nonlinear stiffness coefficient expression and an improved viscous damping coefficient expression considering the wear reduction properties of coatings, so as to obtain a conformal contact force model based on the analysis and comparison of the existing common normal contact force models. The new contact force model is qualitatively analyzed from three aspects, namely clearance size, recovery coefficient, and material properties, so as to demonstrate the correctness and applicability of the model. In the prefabricated space deployable mechanism (RSSP) with spherical joint clearance, the acceleration variation of the actuator is analyzed and compared by using the new contact force model, and the wear quantity of the spherical joints with clearance and coating is predicted. The dynamic results show that spherical joints with clearance have a significant effect on the acceleration of the actuator, and the long working time will inevitably lead to increased vibration and reduce the motion accuracy and life of the mechanism. By comparing with the calculation results of wear, it is found that the wear of spherical joint clearance with coating decreases significantly in all vector directions, and the wear area of the Euler Angle increases slightly compared with that without coating because of the increase of contact collision frequency. Therefore, the wear calculation method and coating strategy proposed in our work can provide a theoretical basis for improving the kinematic accuracy and working life of space deployable mechanism system considering spherical joints with clearance.

Quadrature-based lattice Boltzmann model for non-equilibrium dense gas flows

The Boltzmann equation becomes invalid as the size of gas molecules is comparable with the average intermolecular distance. A better description is provided by the Enskog collision operator, which takes into account the finite size of gas molecules. This extension implies nonlocal collisions as well as an increase in collision frequency, making it computationally expensive to solve. An approximation of the Enskog collision operator, denoted the simplified Enskog collision operator, is used in this work to develop a quadrature-based lattice Boltzmann model for non-ideal monatomic dense gases. The Shakhov collision term is implemented in order to fine-tune the Prandtl number. This kinetic model is shown to be able to tackle non-equilibrium flow problems of dense gases, namely, the sound wave and the shock wave propagation. The results are compared systematically with the results of the more accurate but computationally intensive particle method of solving the Enskog equation. The model introduced in this paper is shown to have good accuracy for small to moderate denseness of the fluid (defined as the ratio of the molecular diameter to the mean free path), and due to the efficiency in terms of computational time, it is suitable for practical applications.

Dual-miRNA-Propelled Three-Dimensional DNA Walker for Highly Specific and Rapid Discrimination of Breast Cancer Cell Subtypes in Clinical Tissue Samples

Dual-miRNA-Propelled Three-Dimensional DNA Walker for Highly Specific and Rapid Discrimination of Breast Cancer Cell Subtypes in Clinical Tissue Samples

Effect of shear stress on collisional electromagnetic modes in the fast ignition

In the present work, the effect of the shear stress and collision within the turbulent plasma of the fuel fusion on the Weibel instability growth rate is explored using a kinetic model. The collisions are responsible for taking energy from the plasma electromagnetic wave and hence stop the wave from growing further in the fusion fuel plasma. It is found that the minimum value of the stress rate threshold for the purely transversal mode is greater than that of the transverse-longitudinal coupled mode. For product purely transverse mode, the growth rate is more as compared to the transverse-longitudinal coupled mode. The presence of the collisions has a negative effect on the Weibel instability growth rate. At small wavelengths limit, an increase in collision frequency decreases the growth rate of the Weibel instability, and for a product in the transverse-longitudinal coupled mode, the growth rate is more as compared to the purely transverse mode. In the case of large wavelengths, only for purely transverse modes, decreasing by 57% collision frequency leads to about 0.087% decrement in the maximum of the Weibel instability growth and for a product the purely transverse mode, the growth rate is more as compared to the transverse-longitudinal coupled mode.

Which factor determines the optical losses in refractory tungsten thin films at high temperatures?

Refractory tungsten (W) plays an important role in high temperature photonic/plasmonic applications. Previously room temperature bulk single/poly-crystalline optical constants were extensively used to calculate the optical properties of W nanostructures at high temperatures. This might lead to a significant deviation between the predicted and measured optical properties due to the exclusion of electron–phonon interaction, as well as grain-boundary and surface-scattering.Herein, we show experimentally, how film thickness and temperature affects the optical losses in W. A drastic increase in the effective electron collision frequency is observed with decreasing the film thickness down to 5 nm, due to the grain-boundary and surface-scattering mechanisms. At sufficiently high temperatures (greater than 200 °C for W), the electron–phonon interaction eventually becomes the dominant mechanism, linearly increasing collision frequency with temperature, and it is independent of the geometry of the thin film structure. The impact of thickness and temperature-dependent optical properties of W is showcased with a hyperbolic 1D metamaterial structure acting as a thermophotovoltaic emitter. This work opens new directions in accurate prediction of the optical properties of nanostructures and design of efficient devices in various applications, such as aerospace, energy-efficient lighting, radiative cooling and energy harvesting, by incorporating thickness and temperature-dependent optical constants.

Copper-promoted heterogeneous Fenton-like oxidation of Rhodamine B over Fe3O4 magnetic nanocatalysts at mild conditions.

Rhodamine B (RhB) is used in various industries and its effluent must be effectively treated because of its harmful and carcinogenic nature. In this work, ionothermally synthesized Cu-doped Fe3O4 magnetic nanoparticles (Cu-Fe3O4 MNPs) were found to be a highly efficient heterogeneous Fenton-like catalyst for complete decolorization of the RhB solution with H2O2 at pH ~ 7 and 25 °C. The effects of the catalyst loading, initial concentrations of RhB and H2O2, co-existing natural organic matter and inorganic salts, reaction temperature, and radical scavengers on the catalytic performance of Cu-Fe3O4 were investigated. Monte-Carlo simulations revealed that copper dopants facilitated the activation of H2O2 via adopting a terminal end-on adsorption mode and increased collision frequency by bringing the RhB molecules closer to H2O2 and the magnetite surface. These theoretical calculations provide new insight into the promotional effect of copper dopants in magnetite at molecular level.

A tunable narrow-band plasma photonic crystal filter based on bound state

Photonic crystals are widely used in a class of narrow-band frequency selective filter due to their excellent ability to control electromagnetic waves, in which the working frequency depends on the structural parameters of the point defect resonant cavity of the photonic crystal, and the introduction of some dispersive media into the cavity makes the filter adjustable. In general, this kind of cavity-filter is very sensitive to the parameter disturbance of the cavity, and the quality factor of the filter can be reduced significantly by material loss. On the other hand, some studies have shown that there may be bound states at the interface between two different photonic crystals, and the bound state is often accompanied by narrow band and high transmittance, which implies that a narrow-band filter based on bound states is feasible. Importantly, filters based on bound states may be resistant to material loss to some degree. In this paper, a bound state related tunable narrow-band filter composed of a one-dimensional photonic crystal and a two-dimensional plasma photonic crystal is proposed, and the working frequency of the filter is located in the common band gap of the two photonic crystals. The COMSOL Multiphysics finite element simulation software is used to study the influences of geometric parameters of the one-dimensional photonic crystal and plasma parameters on the performance of the filter. It is found that the closer to each other the center frequencies and depths of the two different forbidden bands are, the greater the peak transmittance of the filter, in which the center frequency dominates, will be. On the other hand, the working frequency of the filter is directly proportional to plasma density and inversely proportional to collision frequency. The quality factor of the filter first increases and then decreases with the increase of plasma density, and decreases with the increase of collision frequency. The peak transmittance of the filter first increases and then decreases with the increase of plasma density, and decreases with the increase of plasma collision frequency. Finally, with the increase of collision frequency, both the peak transmittance and the quality factor decrease slightly, which indicates that the filter has a certain resistance to plasma loss. We believe that this work is helpful in investigating some new plasmonic photonic crystal filters.

Simulation of the optical properties of gold nanoparticles on sodium alginate

In this contribution, we report on the simulation of optical reflectance and transmittance (R&T) taken on a set of gold nanoparticles thin film, deposited on sodium alginate by magnetron sputtering. The gold layer is very thin, so that the films are not continuous and the material is arranged in nanostructured layers. R&T spectra are simulated using the Generalized Transfer Matrix method applied to the film-on-substrate model. The gold NP films are simulated using the Drude-Lorentz model, by taking into account that the optical function of nanostructured gold exhibits increased collision frequency and reduced relaxation time. Moreover, the signal of localized surface plasmon, evident in the spectra, is simulated by introducing a dedicated modified Lorentz oscillator. The experimental results are well reproduced by the applied model. All trends (amplitude and energy position of the plasmon oscillator, film thickness, relaxation time) are correlated with the deposition parameters. The procedure represents a useful tool in the characterisation of such nanoparticles thin films.

Ultrathin Octahedral CuPt Nanocages Obtained by Facet Transformation from Rhombic Dodecahedral Core–Shell Nanocrystals

Copper is an earth-abundant element that can be used to reduce the high cost and unsatisfactory durability of pure Pt catalysts by the formation of bimetallic Pt–M nanocrystals. Among CuPt nanostructures, nanocages attract great interest for catalysis as they allow passage of reactant species to their porous interiors, which provide a high fraction of surface sites. They may also enhance reactivity through an increase in collision frequency by enclosing reagents within nanoscale cavities and by lattice strain effects of the alloy. Recent reports apply solvothermal chemistry to obtain CuPt nanocages in one step. However, there is still a lack of understanding in the formation mechanism and its impact on catalytic activity for such hollow CuPt nanostructures. In this work, we adopt a two-step method in which we synthesize rhombic dodecahedral (RD) Cu–CuPt core–shell nanocrystals by the deposition of Pt on Cu nanocubes to form CuPt shells less than 2 nm in thickness, followed by removing Cu cores to obtain ultrathin octahedral (OCT) nanocages for catalytic applications. By adjustment to shorter and longer reaction time frames, the core–shell nanocrystals were also made into quasi-RD (QRD) and spiny-RD (SRD) morphologies, which lead to porous (POCT) and spiny (SOCT) OCT nanocages, respectively, upon etching. These three types of CuPt nanocages (POCT, OCT, and SOCT) were then examined in the electrocatalytic oxygen reduction reaction (ORR) and the hydrogen evolution reaction (HER) by the hydrolysis of NH3BH3 to study their performance. As a result, the SOCT CuPt nanocages exhibit the highest Pt mass activity (0.3 A/mgPt) in the ORR, a 3-fold improvement over commercial Pt/C. They also show the lowest activation energy (24.3 kJ/mol) in the HER that is better than the commercial catalyst by a factor of 4. HER photocatalysis results show that the POCT and OCT nanocages have localized surface plasmon resonance (LSPR)-enhancement while the SOCT nanocages do not, which is attributed to inhomogeneity in Cu–Pt distributions at shorter reaction times.

Molecular dynamic simulation of bubble nucleation in a nanochannel with a groove

Molecular dynamics methods are used to investigate the effect of wall wettability and initial fluid density on the nucleation and growth of nanobubbles in a nanochannel with a groove. Surface wettability is controlled by adjusting the parameters of the solid-liquid potential energy and the results show that groove wettability greatly influences the bubble nucleation process. In the case of a groove with a weak solid-liquid interaction, fluid atoms in the groove are strongly affected by repulsive forces attributed to solid atoms, the density of the fluid atoms is low, and atomic collision frequency increases. The local activation energy is concentrated in the groove, resulting in bubble nucleation. In the case of a groove with a stronger solid-liquid interaction, the bubble is formed in the center of the nanochannel. In general, the bubble radius of curvature and contact angle remain unchanged during the growth process in the case of a uniform wettability nanochannel with a groove, while significant changes are observed for a nonuniform wettability nanochannel. The radius of curvature for the generated bubble increases with increasing fluid initial density, while the steady contact angle decreases. At the request of the authors this paper is being retracted. This action is taken because in the simulation cases of β=0.3 and β=0.4, the temperature control method is incorrect, resulting in flawed simulation results in Figs. 8 and 9. In addition, the number of atoms (and hence the density) in the simulation box is also not correct due to errors in the initialization phase of the simulation. Thus, the calculated phase diagram in Fig. 2 is incorrect. The authors sincerely apologize for these errors and omissions and regret any inconvenience they may have caused.