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There is a consensus that we are conscious of something greater than ourselves, as if we are derived from some other primordial set of principles. Classical or Newtonian physics is based on the Laws of Nature. Conversely, in a recent series of articles, it has been hypothesized that the cell was formed from lipid molecules submerged in the primordial ocean that covered the earth 100 million years after it formed. Since lipids are amphiphiles, with both a positively- and negatively-charged pole, the negatively-charged pole is miscible in water. Under the influence of earth's gravity, the lipid molecules stand up perpendicularly to the surface of the water, packing together until the negative charge neutralizes the Van der Waals force for surface tension, causing the lipid molecules to 'leap' into the micellar form as a sphere with a semi-permeable membrane. Particles in the water freely enter and exit such spheres based on mass action. Over time such protocells evolved Symbiogenesis, encountering factors that posed existential threats, assimilating them to form physiology to maintain homeostatic control. Importantly, when differentiated lung or bone cells are exposed to zero gravity, they lose their phenotypic identity in their evolved state, which has been interpreted as transiting from local to non-local consciousness. [ABSTRACT FROM AUTHOR]

AbstractThis study investigates the impact of Casimir, Van der Waals, and electrostatic forces on nanomechanical switches’ thermomechanical and free vibration behavior. The analysis is conducted using a novel higher-order beam theory and the nonlocal strain gradient elasticity. The motion equations of the nanosensor/switch beam are derived using Hamilton’s principle and solved using Navier’s method for general boundary conditions. The nanoswitch is composed of electroelastic barium-titanate (BaTiO3) and magnetostrictive cobalt-ferrite (CoFe2O4) materials, which are modeled using a power-law approach to account for functionally graded material property variations across the beam’s thickness. The impact of different parameters, such as Casimir, Vander Waals, electrostatic forces, and variations in material composition, size parameters, and gap distance, on a nanoswitch system’s bucking and free vibration is comprehensively examined. With the intermolecular and electrostatic forces, the temperature dependency of barium-titanate and cobalt-ferrite nanoswitch materials, which have not been extensively studied in any previous research, is considered in the modeling of free vibration, and the buckling behavior of a nanoswitch for the first time. This research represents the first comprehensive analysis of these factors. Considering the investigated parameters, the study’s findings can provide helpful insights into developing micro/nano-electromechanical systems, including switches, sensors, and actuators. [ABSTRACT FROM AUTHOR]

Field electron emission characteristics of the carbon nanotube (CNT) film emitters were investigated according to densification conditions such as nitric acid, acetic acid, and salicylic acid. The emission performance of the CNT film emitters was strongly affected by the densification conditions. Salicylic acid exhibits the best field electron emission properties of the CNT film emitters, followed by nitric acid and acetic acid. The efficient densification of the CNT film emitter by salicylic acid is caused by the role of polarity and p orbitals, nitric acid by hydrogen ions, and acetic acid by weak polarity. After the densification with salicylic acid, the turn-on field of the CNT film emitter decreases from 1.94 V μ m−1 to 1.86 V μ m−1, the threshold field decreases from 3.41 V μ m−1 to 2.95 V μ m−1, the emission current significantly increases from 20.92 mA to 43.98 mA, and the degradation rate from the long-term emission stability decreases from 49.9% to 21%. The improved emission characteristics are attributed to the increased emission sites at the CNT film and the increased electrical conductivity of the CNT film. The densification is a useful way to enhance the field electron emission properties of CNT film emitters. [ABSTRACT FROM AUTHOR]

The Lamb shift, one of the most fundamental interactions in atomic physics, arises from the interaction of H atoms with the electromagnetic fluctuations of the quantum vacuum. The energy shift has been computed in a variety of ways. The energy shift, as Feynman, Power, and Milonni demonstrated, equals the change in the vacuum energy in the volume containing the H atoms due to the change in the index of refraction arising from the presence of the H atoms. Using this result and a group theoretical calculation of the contribution to the Lamb shift from each frequency of the vacuum fluctuations, in this paper we obtain an expression for the region of the vacuum energy for each frequency ω around the H atom due to the Lamb shift. This same field plays an essential role in the van der Waals force. We show the ground state atom is surrounded by a region of positive vacuum energy that extends well beyond the atom for low frequencies. This region can be described as a steady state cloud of vacuum fluctuations. For energies E = ℏ ω less than 1 eV, where ℏ is the reduced Planck constant and ω is frequency, the radius of the positive energy region is shown to be approximately 14.4/E Å. For a vacuum fluctuation of wavelength, λ , the radius is (α / 2 π) λ , where α is the fine-structure constant. Thus, for long wavelengths, the region has macroscopic dimensions. The energy–time uncertainty relation predicts a maximum possible radius that is larger than the radius based on the radiative shift calculations by a factor of 1 / 4 α . [ABSTRACT FROM AUTHOR]

System of nonlinear partial differential equations, which describes the multi-walled carbon nanotube nonlinear oscillations, is derived. The Sanders–Koiter nonlinear shell theory and the nonlocal anisotropic Hooke's law are used. Three kinds of nonlinearities are accounted. First of all, the van der Waals forces are considered as nonlinear functions of the radial displacements. Secondly, the nanotube walls displacements have moderate values, which are described by the geometrically nonlinear shell theory. Thirdly, as the stress resultants are the nonlinear functions of the displacements, the additional nonlinear terms are accounted in the equations of motions. These terms are derived from the natural boundary conditions, which are used in the weighted residual method. The finite degrees of freedom nonlinear dynamical system is derived to describe the oscillations of nanostructure. The multi-mode invariant manifolds are used to describe the free nonlinear oscillations, as the dynamical systems have the internal resonances 1:1. The motions on the invariant manifolds are described by two degrees of freedom nonlinear dynamical systems, which are studied by the multiple scales method. The backbone curves of the nonlinear modes are analyzed. As follows from the results of the numerical simulations, the eigenmode of low eigenfrequency has commensurable longitudinal, transversal and circumference displacements. In this case, the nonlinear parts of the van der Waals forces harden essentially the backbone curve of the oscillations. [ABSTRACT FROM AUTHOR]

Casimir–van der Waals forces are important in the self-assembly processes of nanoparticles. In this paper, using a hybrid approach based on Lifshitz theory of Casimir–van der Waals interactions and corrections due to the shape of the nanoparticles, it is shown that for non-spherical nanoparticles, the usual Hamaker approach overestimates the magnitude of the interaction. In particular, the study considers nanoplates of different thicknesses, nanocubes assembled with their faces parallel to each other, and tilted nanocubes, where the main interaction is between edges.

Adhesion is the attraction between dissimilar atoms of surfaces or particles, wherein a normal force is required to separate them. Various reasons for adhesion include electrostatic force, capillary force and hydrophobic force. Adhesion due to van der Waals force caused by the attraction between permanent or induced atomic/molecular dipoles has a special significance as it is always present. Adhesion plays a prominent role in the contact interactions at small scales, and understanding them is important in studies on the origin of friction and wear. The finite element method is employed to analyse adhesive contact, wherein the adhesive force is modelled as a body force derived from Lennard–Jones potential. Adhesive contact between an elastic cube (asperity) and the surface of a semi-infinite rigid body has been analysed using this approach. The numerical results obtained are compared with the analytical expressions for interaction free energy based on the idealized power-law forms proposed by Parsegian. [ABSTRACT FROM AUTHOR]

Domestic liquid waste has become the leading cause of aquatic pollution, with a percentage of 60-70%. One of the media that has the potential to process water is coco fibre. This study aimed to analyze the Effectiveness of both media in reducing restaurant waste. The experiment was conducted with variations in the Thickness of coco fibre and activated carbon media of 10, 15, and 20 cm and sand 40 mesh of 10 cm. The addition of sand media proved more effective in meeting quality standards with the Effectiveness of the reduction of Total Suspended Solid (TSS), Chemical oxygen demand (COD), and turbidity, the highest obtained at the Thickness of coco fibre media 20 cm activated carbon 20 cm, and sand 40 mesh 10 cm, which is respectively 95.78, 93.04, and 98.72%, which is influenced by the Thickness and time of contact of waste with the media.

Photocatalysis is a prospective technology to solve the current environment and energy crisis. The exploitation of 2D photocatalyst materials is a research hotspot owing to their large specific surface area, intrinsic defect and abundant active sites. Particularly, 2D/2D heterojunctions own intimate interfaces with expanded contact areas, which is beneficial to facilitate the separation and transportation of electron-hole pairs and further improve the photocatalytic activity. Currently, most studies focus on the band structure alignment in the design of 2D/2D heterojunctions, while the importance of interfacial binding forces is often ignored. This review aims at highlighting the critical role of interfacial binding forces in the photocatalytic activity of 2D/2D heterojunctions for the first time. First, we classify the types of interfacial forces, including electrostatic force, van der Waals force, covalent bond, hydrogen bond. Then we summarize several typical strategies for constructing 2D/2D heterojunctions with corresponding structural features. Importantly, the photocatalytic mechanism is discussed based on interfacial composition, charge transfer path and modification of active sites, and various photocatalytic applications are summarized. Finally, we outline the challenges and future development in this prospective research field. It is expected to fill the existing knowledge gap on interfacial binding forces for designing efficient 2D/2D heterojunctions rationally. • The types of different interfacial binding forces are introduced. • The construction strategies of different interfacial binding forces are reviewed. • The key role of interfacial binding forces of 2D/2D heterojunctions is summarized. • Prospects of 2D hybrids in energy and environment photocatalysis are discussed. [ABSTRACT FROM AUTHOR]

We consider steady states with mass constraint of the fourth-order thin-film equation with van der Waals force in a bounded domain which leads to a singular elliptic equation for the thickness with an unknown pressure term. By studying second-order nonlinear ordinary differential equation, \begin{equation*}h_{rr}+\frac{1}{r}h_{r}=\frac{1}{\alpha}h^{-\alpha}-p\end{equation*} we prove the existence of infinitely many radially symmetric solutions. Also, we perform rigorous asymptotic analysis to identify the blow-up limit when the steady state is close to a constant solution and the blow-down limit when the maximum of the steady state goes to the infinity. [ABSTRACT FROM AUTHOR]

Group III-nitrides have attracted significant attention in recent years for their wide tunable band-gaps and excellent optoelectronic capabilities, which are advantageous for several applications including light-emitting diodes, lasers, photodetectors, and large-size low-cost power electronic devices. However, conventional epitaxy accompanied by the covalent bond formation renders the transfer of nitride epilayers difficult, thereby limiting the application potential of nitrides in wearable and flexible electronics. Furthermore, interfacial covalent bonds also limit substrate selection and hinder the development of heterogeneous integration between nitrides and other material systems. 2D materials can mitigate these problems significantly. On the one hand, due to the weak van der Waals forces between the layers of 2D materials, influences of lattice mismatch can be avoided to improve crystal quality. On the other hand, delamination and transfer of nitride epilayers can be achieved easily. Therefore, this study focuses on providing comprehensive guidelines regarding the exfoliation of epitaxial layers using 2D materials to provide new design freedoms for nitride devices. Different 2D buffers and release layers have also been discussed. Furthermore, the limitations, promising solutions, future directions, and applicability of this strategy to flexible nitride devices are presented. [ABSTRACT FROM AUTHOR]

This paper proposes a hybrid algorithm based on the ant colony and Physarum Polycephalum algorithms. The positive feedback mechanism is used to find the globally optimal path. The crossover and mutation operations of the genetic algorithm are introduced into the path search mechanism for the first time. The Van der Waals force is applied to the pheromone updating mechanism. Simulation results show that the improved algorithm has advantages in quality and speed of solution compared with other mainstream algorithms. This paper provides fast and accurate route methods for solving the Traveling Salesman Problem first and a delivery scheme is also presented for UAVs to realize "contactless delivery" to users in the Changchun Mingzhu District during the COVID-19 epidemic, which confirms the practicability and robustness of the algorithm. [ABSTRACT FROM AUTHOR]

Casimir–van der Waals forces are important in the self-assembly processes of nanoparticles. In this paper, using a hybrid approach based on Lifshitz theory of Casimir–van der Waals interactions and corrections due to the shape of the nanoparticles, it is shown that for non-spherical nanoparticles, the usual Hamaker approach overestimates the magnitude of the interaction. In particular, the study considers nanoplates of different thicknesses, nanocubes assembled with their faces parallel to each other, and tilted nanocubes, where the main interaction is between edges. [ABSTRACT FROM AUTHOR]

The fluid flow in the small pore throat is a nonlinear flow, and the microscopic force between the fluid and the wall cannot be ignored. However, the previously established theories about the leakage between sealing interfaces have not considered the influence of microscopic forces. Based on contact mechanics and percolation theory, the void characteristics of the sealing interface were clarified, and the influence of microscopic force on fluid flow in porous medium was analyzed. Combined with the capillary force, the concept of a critical void radius between the mechanical seal interfaces is proposed. The fluid flow resistance model and leakage rate calculation equation of the sealing interface considering the van der Waals force are established, and the leakage judgment criterion of the sealing interface is provided. Through numerical calculation and experiments, the effect of microscopic force is verified in terms of the fluid flow law and macroscopic leakage rate. The results show that van der Waals forces have an important influence on the fluid flow between the sealing interfaces. As the microchannel size decreases, the van der Waals forces between solid and liquid increase, and the influence of these van der Waals forces on the fluid flow between the sealing interfaces cannot be ignored. The calculation model of the sealing interface leakage rate proposed in this paper shows little difference with the results of the Persson model, and is in good agreement with the experimental results; the maximum relative error is 8.7%, the minimum relative error is only 3.8%. [ABSTRACT FROM AUTHOR]

The coal deformation was induced by the gas adsorption of N2, CH4, and CO2. However, the differences between different gas adsorption performances and the deformation mechanism of coal need to be further studied. In this study, the experiments were conducted using self‐developed equipment to reveal the adsorption characteristics of different gases. The results showed that the gas adsorption capacity followed the sequence of CO2 > CH4 > N2. The gas adsorption capacity was negatively correlated with temperature. The maximum decrease in adsorption capacity (23.70%) was N2. The gas adsorption capacity was positively correlated with gas pressure. The maximum increase in gas adsorption capacity (232.79%) was N2. Correspondingly, the coal deformation of CO2 was the largest, and that of N2 was the smallest. The maximum decrease in deformation (31.09%) was CO2 during the temperature increase. The initial coal deformation rates of N2, CH4, and CO2 were 0.060, 0.091, and 0.042 mm·h−1, respectively. The maximum increase of deformation (234.65%) was CH4 with the gas pressure increase. The initial coal deformation rates of N2, CH4, and CO2 were 0.024, 0.045, and 0.016 mm·h−1, respectively. This work guided further clarifying the mechanism of different gases' adsorption capacity and coal deformation. [ABSTRACT FROM AUTHOR]

The molecular behavior of aromatic compounds on the biochar surface， especially the mechanism of weak interaction， is not yet clear. In order to reveal the mechanism of weak interaction between biochar and phenol， adsorption isotherm and adsorption kinetics experiments， as well as FT-IR characterization were used to analyze the binding energy， reduced density gradient (RDG) and electron density topological relationship between biochar and phenol of different adsorption configurations with density functional theory (DFT). Results showed that the adsorption isotherm reaches the equilibrium after 72h， pH significantly affects the saturated adsorption capacity， and the adsorption capacity is the largest at pH=6. The functional groups on the biochar surface are the adsorption centers. The adsorption enthalpy (ΔH) is always in the range of hydrogen bond energy. The weak interaction of the four adsorption configurations (A/B/C/D) is dominated by van der Waals forces and weak hydrogen bonds. The B configuration has the lowest binding energy and the most stable. The C configuration has the strongest weak interaction， and the D configuration is the weakest. [ABSTRACT FROM AUTHOR]

Adhesive force due to van der Waals interactions plays a significant role in contact interactions at small scale. In this work, we propose a novel simulation module for performing adhesive contact analysis using a finite element (FE) software, based on a lumped parameter formulation. The numerical results are validated by comparing with analytical results. The proposed model significantly reduces computational resource requirements compared to direct implementation of body force in FE software. Adhesion-induced instability (jump-to-contact) phenomenon is studied with the help of this computational model. Finally, we demonstrate the applicability of the proposed formulation by studying the effect of adhesion applied to cantilever dynamics on an atomic force microscope. [ABSTRACT FROM AUTHOR]

Recent studies have revealed the importance of powder transport by gas-phase flows in the laser-interaction zone in laser powder bed additive manufacturing. The understanding of such a mass transfer mechanism is necessary for developing and optimizing laser-assisted processes of additive manufacturing. Powder bed surface relief around the remelted track is experimentally characterized by metallography and laser scanning profilometry in single-track experiments with powders of various materials and various particle sizes. Denudation zones with sharp irregular boundaries containing particle agglomerates are observed for finer powders with smaller particles. Denudation zones without well-defined boundaries containing single particles are observed for coarser powders. The balance of forces applied to a particle is theoretically analyzed to understand powder rearrangement in the laser-interaction zone. The drag force is estimated by a similarity point-source model of the entrainment flow with a correction for the finite size of the evaporation spot. The adhesion force appears to be greater than the gravity one for the fine powders and lower than the gravity for the coarse powders, thus explaining the observed difference in the denudation zone morphology. The measured variation of the denudation width with the material properties and the particle size is consistent with the theoretical predictions. [ABSTRACT FROM AUTHOR]

• Particle-size effects on aeolian deposition and sediment structure were examined. • Two distinct structures form during air-fall deposition as particle sizes vary. • The relevance between interparticle forces and gravity control structure formation. • A dimensionless granular bond number Bo captures the relevance of governing forces. • Open and collapsible structures form due to special accumulation behavior at Bo < 10. Aeolian deposition is significant to the landscape formation on Earth and even other planetary bodies. Particle size controls the transport distance of particles. However, the understanding of particle-size effects on the structure and mechanical behavior of aeolian accumulations remains limited. We investigate the effect of particle size on the structure and collapse of aeolian sediments by one-dimensional compression and collapse tests following the initial air-fall deposition of particles of various sizes from sand to fine silt. Results reveal that the relevance between interparticle forces and gravity controls the formation of two distinct sediment structures as the particle size varies. A loose structure with a packing density close to the simple cubic packing forms for sands and is not collapsible. An open structure with higher porosity forms as particle size becomes smaller. The structure can stack vertically. The stacking height, porosity, and collapsibility increase as particle size decreases. A dimensionless granular bond number Bo captures the relevance between van der Waals forces and gravity. A threshold particle size corresponding to Bo = 10 is identified, below which open and collapsible structures form. The structure forms due to distinctive accumulation behavior. Particle interaction forces create porous aggregates, stabilize the aggregate as it contacts the deposit, and retain open pores. The effect of fine particles on properties of deposited mixtures is also analyzed. Results are relevant to understanding the formation of collapsible aeolian deposits on Earth and may contribute to the estimation of the physical properties of aeolian sediments on other planetary bodies. [ABSTRACT FROM AUTHOR]

Copyright of Journal of South China University of Technology (Natural Science Edition) is the property of South China University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper proposes a hybrid algorithm based on the ant colony and Physarum Polycephalum algorithms. The positive feedback mechanism is used to find the globally optimal path. The crossover and mutation operations of the genetic algorithm are introduced into the path search mechanism for the first time. The Van der Waals force is applied to the pheromone updating mechanism. Simulation results show that the improved algorithm has advantages in quality and speed of solution compared with other mainstream algorithms. This paper provides fast and accurate route methods for solving the Traveling Salesman Problem first and a delivery scheme is also presented for UAVs to realize “contactless delivery” to users in the Changchun Mingzhu District during the COVID-19 epidemic, which confirms the practicability and robustness of the algorithm.

In view of the threat of metal particles to the insulation performance of AC GIL (Gas insulated transmission line), this paper uses aluminum powder to simulate the metal particles which are closer to the engineering practice, A scaled-down model similar to the actual GIL structure was built to study the movement characteristics of aluminum powder in GIL. The discharge, movement and distribution characteristics of aluminum powder was recorded in experiment. The research shows that the particles from spacer to the part below the shielding should be prevented. The particles with particle size of about 150 mesh move more violently. At the same time, the movement of powder particle in GIL is affected by Van der Waals force. According to the characteristics of particle motion distribution, grid-shaped trap and strip-shaped trap were designed and compared in this paper, and the trap capture coefficient was proposed. Finally, the suggestion of particle trap arrangement is put forward, that is, grid-shaped trap can be set near the spacer, and strip-shaped trap can be selected for the rest of the GIL.

Investigation on the adhesion effect of lunar dust particles on contacting interface improves in lunar dust protection and prolongs the equipment service life. In this work, the contact mathematical adhesion model between an ultra-fine lunar dust particle and the aluminum-based rough surface is established based on the fractal theory. The research shows that the van der Waals force dominates adhesion force for ultra-fine lunar dust particles in space environment and is directly related to the rough surface fractal parameters, namely the fractal dimension parameter D , fractal roughness G as well as root-mean-square roughness(rms). Based on van der Waals adhesion model, the optimum rough surface fractal parameters are obtained through model optimization when the van der Waals force is minimal. The van der Waals forces reaches the minimum for lunar dust particle with diameters of 500 nm and 2.5 μm when the rms is 2.689 nm and 4.7 nm respectively. To validate the effectiveness of using fractal theory to the surface topography in van der Waals force calculation, the dust residual rates have been compared with the aluminum surfaces prepared using chemical etching method, electrochemical etching method, and combined chemical method. Based on the AFM topography of the surfaces, the van der Waals forces have been calculated between the lunar dust particles and the surfaces prepared using different etching methods. The centrifugal experiments suggest that van der Waals force is positively related to the dust residual rates. In summary, the fractal theory is effective in describing the surface roughness in lunar dust adhesion problems and it can be used in future lunar dust protection surface design and applications. [ABSTRACT FROM AUTHOR]

[Display omitted] Analytical expressions for calculating Hamaker constant (HC) and van der Waals (VDW) energy/force for interaction of a particle with a solid water interface has been reported for over eighty years. This work further developed novel analytical expressions and numerical approaches for determining HC and VDW interaction energy/force for the particle approaching and penetrating air–water interface (AWI), respectively. The expressions of HC and VDW interaction energy/force before penetrating were developed through analysis of the variation in free energy of the interaction system with bringing the particle from infinity to the vicinity of the AWI. The surface element integration (SEI) technique was modified to calculate VDW energy/force after penetrating. We explain why repulsive VDW energy exists inhibiting the particle from approaching the AWI. We found very significant VDW repulsion for a particle at a concave AWI after penetration, which can even exceed the capillary force and cause strong retention in water films on a solid surface and at air–water-solid interface line. The methods and findings of this work are critical to quantification and understanding of a variety of engineered processes such as particle manipulation (e.g., bubble flotation, Pickering emulsion, and particle laden interfaces). [ABSTRACT FROM AUTHOR]

Recognizing that either the retarded van der Walls (sometimes called the Casimir) or the full van der Walls force always acts between two flat surfaces that are in close proximity to each other, we analyze the stiction phenomenon in nanoelectromechanical systems (NEMS) composed of a single layer of graphene suspended over a stationary rigid substrate of graphene by using both molecular dynamics (MD) simulations and a linear elasticity theory. Stiction occurs when the initial gap between the deformable and the stationary electrodes of a NEMS is small enough for the two electrodes to touch each other in the absence of any applied potential difference between them. The value of the initial gap at stiction is called the critical gap and determines the fabricability of the device. In this work, an NEMS is modelled as a pre-stressed clamped atomic graphene structure in the form of either a rectangular strip or a solid/annular circular initially flat disk suspended over a rigid flat substrate and the critical gap found as a function of the prestress. Both methods involve different challenges – the MD work requires properly estimating the Casimir force and the continuum problem has a deflection-dependent external force. It is shown that results from the two approaches qualitatively agree with each other. For the continuum problem we provide a simple expression for estimating limiting dimensions of the NEMS. [ABSTRACT FROM AUTHOR]

In this work, surface/interface effects for pull-in voltage and viscous fluid velocity effects on the dimensionless natural frequency of fluid-conveying multiwalled piezoelectric nanosensors (FC-MWPENSs) based on cylindrical nanoshells is investigated using the Gurtin–Murdoch surface/interface theory. The nanosensor is embedded in a viscoelastic foundation and subjected to nonlinear van der Waals and electrostatic forces. Hamilton’s principle is used to derive the governing and boundary conditions and is also the assumed mode method used for changing the partial differential equations into ordinary differential equations. The influences of the surface/interface effect, such as Lame’s constants, residual stress, piezoelectric constants and mass density, are considered for analysis of the dimensionless natural frequency with respect to the viscous fluid velocity and pull-in voltage of the FC-MWPENSs.

Copyright of Journal Of Sichuan University (Natural Sciences Division) / Sichuan Daxue Xuebao-Ziran Kexueban is the property of Editorial Department of Journal of Sichuan University Natural Science Edition and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

[Display omitted] • CsPbBr 3 with quantum-limited domain effects have reversible hydrochromic properties. • Different Organic solvents cause polarity-related discoloration of composites. • A detection model was developed for all-organic solvent polarity detection. Hydrochromic materials have received much attention in anticounterfeiting due to their reversible photoemission properties toward water. However, existing hydrochromic materials usually suffer from slow hydrochromic response and limited stability, repeatability, and color tunability. This paper found for the first time that CsPbBr 3 /Cs 4 PbBr 6 composites with quantum-limited domain effects had reversible hydrochromism. CsPbBr 3 /Cs 4 PbBr 6 composites were successfully synthesized in molecular sieve MCM-41 using an improved mechanochemical method. The composites underwent a reversible phase transition from Cs 4 PbBr 6 /CsPbBr 3 to CsPbBr 3 upon treatment with a trace amount of water, the photoluminescence colors underwent a change from blue to green, and reversion occurred due to heating. Mechanistic investigation revealed that quantum dots underwent soft agglomeration due to van der Waals forces in polar solvent environments, affecting the action of quantum domain-limiting effects. Therefore, organic solvents with different polarities can cause different degrees of reversible discoloration of the material. This study provides new ideas for understanding the phase transition and agglomeration of metal halide perovskite quantum dots in polar solvent environments. Additionally, it offered new options for aqueous color-changing materials and organic solvent polar detection materials. [ABSTRACT FROM AUTHOR]

The integration of dissimilar semiconductor materials holds immense potential for harnessing their complementary properties in novel applications. However, achieving such combinations through conventional heteroepitaxy or wafer bonding techniques presents significant challenges. In this research, we present a novel approach involving the direct bonding of InGaAs-based p-i-n membranes with GaN, facilitated by van der Waals forces and microtransfer printing technology. The resulting n-InP/n-GaN heterojunction was rigorously characterized through electrical measurements, with a comprehensive investigation into the impact of various surface treatments on device performance. The obtained InGaAs/GaN photodetector demonstrates remarkable electrical properties and exhibits a high optical responsivity of 0.5 A/W at the critical wavelength of 1550 nm wavelength. This pioneering work underscores the viability of microtransfer printing technology in realizing large lattice-mismatched heterojunction devices, thus expanding the horizons of semiconductor device applications.

[Display omitted] Wettability effect has long been a concern in various aqueous lubrication systems including biological and industrial applications. The wettability may affect lubrication performance by changing interfacial viscosity or hydration force. The key point to reveal the mechanism is to design an ideal experimental system to exclude other bulk factors other than surface wettability. In this work, silicon surfaces with different treatments were used to study the single factor effect of wettability on aqueous lubrication. The normal and friction forces of these surfaces were quantified by atomic force microscopy (AFM) in water environment. The interfacial viscosity was evaluated according to the probe dynamic approaching process. Macroscale and microscale lubrication experiments of other materials were also conducted as verification and supplement. A semi-quantitative relationship between friction and wettability was revealed and attributed to the competition between the attractive van der Waals interactions and wettability-dependent repulsive hydration interaction, which determined the strength of the adhesive interaction and dominated the sliding energy dissipation. The contribution of viscous effect of water was considered to be relatively minor. The findings provide an in-depth understanding of aqueous lubrication and outline important guidelines for tuning adhesion and friction. [ABSTRACT FROM AUTHOR]

The development of micromanipulation technology has an important impact on the research in the microfield, which mainly focuses on the preparation and assembly of microcomponents, in which the microcomponent picking technology is used. The existing picking methods mainly use manipulation tools to clamp or adsorb components, which may destroy or fail to pick objects in the process of manipulation, and the efficiency is relatively low. In order to solve the problems in the existing manipulation methods, a new metal microcomponent picking method based on electrochemistry is proposed, which mainly uses the electrochemical principle to produce metal deposition, connect the manipulation tool and the object, and indirectly control the object by moving the manipulation tool. In this paper, the simulation software ABAQUS is used to pick up the microcopper wires with the length of 100, 200 and 300 μ m by using a pipette with a nozzle diameter of 15 μ m. The force curve between the tool and the object during the manipulation process is obtained. The feasibility of the method is verified by theoretical analysis and simulation experiments. [ABSTRACT FROM AUTHOR]

Soil aggregate breakdown is the key step of splash erosion. Recent studies have shown that it is the soil internal forces that induce aggregate breakdown and subsequent splash erosion. However, little is known about the size characteristics of soil aggregate breakdown and corresponding effects on splash erosion. In this study, Cinnamon soil and Heilu soil were adopted to investigate the effects of soil internal forces on the characteristics of aggregate fragments and splash erosion through wet sieving and rainfall simulation. The results showed the following. (1) With a decrease in electrolyte concentration in soil solution, soil net repulsive force increased; meanwhile, aggregate stability decreased and splash erosion rate increased. Additionally, when the electrolyte concentration was less than 10−2 mol L−1, soil net repulsive force hardly changed, and aggregate stability and splash erosion rate accordingly varied very little. (2) With the increase in the soil net repulsive force, the content of fragments <0.053 mm released from aggregates increased, whereas the content of fragments >0.25 mm decreased, thus suggesting that the aggregates tended to break into fine fractions as soil net repulsive forces increased. (3) Regression analyses showed that soil splash erosion rate decreased linearly with increases in the aggregate stability; moreover, correlation analyses showed that splash erosion rate was significantly and positively correlated with the fragments with a diameter of <0.053 mm, and negatively correlated with the fragments with a diameter of >0.25 mm. This study suggests that soil internal forces induce the aggregate crush and determine the size distribution of fragments available for mobilization by the raindrop impact force. Also, the raindrop impact force is the driving mechanism leading to the movement of fragments. This study provides new insights into the mechanism responsible for splash erosion and could be valuable for controlling soil erosion. Highlights: Soil aggregates breakdown dynamics and splash erosion were quantitatively investigated.Soil internal forces determined the size distribution of fragments after aggregates breakdown.The movement of soil fragments largely depended on raindrop impact force.Splash erosion was driven by the soil internal forces and raindrop impact force. [ABSTRACT FROM AUTHOR]

We developed a method of measuring microscopic ζ potential (ZP) from force vs distance (FD) curves observed by atomic force microscope (AFM). ZP in microscopic regions on wafer surfaces may be one of the most important design guides of chemical mechanical polishing slurries applicable to ultrafine patterned wafers, while ZP is generally observed as an average information for a wide area. Our method is based on the linear correlation between jump-in loads in FD curves observed by the AFM for the blanket wafers (SiO2, SiN and poly-Si) in water systems and ZP of each wafer surface measured by the flow potential method. In the applications of our AFM-based measurement method, material-dependency of ZP on the SiO2/SiN patterned wafer surface and an additive material in a slurry (anionic polymer) adsorbing selectively on the SiN surface of the SiO2/SiN patterned wafer were observed. [ABSTRACT FROM AUTHOR]

Printable organic electronics are attractive owing to its high throughput and easy fabrication. Traditional coating methods (such as inkjet printing) are liquid‐solid contact‐based that deposit liquid solutions onto solid surfaces. Film quality is limited by surface energy of target surfaces and surface tension of the solvents. Furthermore, these printing methods are challenging to directly fabricate films on non‐flat or curved surfaces owing to the fluidity of liquid solution drops. In this work, a water transfer printing method that is solid‐solid contact‐based and assisted by Van der Waals force is reported. Nanometer‐thick films can be deposited on various surfaces: both high‐ and low‐surface energy, both flat and non‐flat surfaces. Water plays two roles: 1) as the transfer medium substrate and providing weak adhesion force between water and the transferred film; 2) high surface tension of water providing room to create surface tension gradient and producing Marangoni force to unfold the crumpled nanometer‐thick films. Electronic and optoelectronics on wrinkled skin and curved surfaces are demonstrated with this water transfer printing method. [ABSTRACT FROM AUTHOR]

The self-attraction of nanowires (NWs) would lead to NWs bunching up together when fabricated in high density and the short circuit of NW-based devices during service. However, the underlying mechanism of the self-attraction of NWs remains debatable due to the lack of in situ characterization of the attraction. In this study, a versatile method of in situ investigating the self-attraction of NWs was developed. The attractive force between two NWs and their distance can be determined quantitatively in the process of attraction under an optical microscope, eliminating the influence of electron beam in electron microscopes. With this approach, the self-attraction of SiC NWs was investigated and a two-stage mechanism for the self-attraction was proposed. The electrostatic force between two individual SiC NWs increased as their distance decreased, and acted as the initial driving force for the attraction of NWs. SiC NWs remained in contact under van der Waals force until they separated when external force exceeded van der Waals force. The charge density and the Hamaker constant of SiC NWs were determined to be 1.9 × 10−4 C·m−2 and 1.56 × 10−19 J, which played an important role in the attraction of NWs. The results shed light on the mechanism of self-attraction among NWs and provide new insights into fabricating high-quality NWs and developing high-performance NW-based devices. [ABSTRACT FROM AUTHOR]

• Stable Pickering emulsion stabilized by pristine TiO 2 nanoparticles was developed. • Emulsions were stabilized by van der Waals force of hydrophilic TiO 2 nanoparticles. • New composite beads were prepared with the obtained vdW -Pickering emulsion. • The composite materials showed high UV blocking ability and enhanced photostability. • Pickering emulsion stabilizing method developed here is simple, general and green. Highly hydrophilic nanoparticles are generally considered not suitable for stabilizing Pickering emulsions, since they could not be effectively wetted by the oil phase at the water-oil interface. However, highly hydrophilic nanoparticles with good dispersity are possibly absorbed and packed onto the surface of the oil droplets in water via the van der Waals attraction between the nanoparticles and the oil droplets. Hence, a novel " van der Waals emulsion" should be possible to be stabilized by highly hydrophilic nanoparticles. Oil-in-water emulsions solely stabilized by pristine TiO 2 nanoparticles (i.e., TiO 2 without any modification or additives) were prepared. The emulsification behavior under varying pH value, oil fraction, particle content and temperature of the emulsion were explored. Composite wax-based beads which encapsulated chemical sunscreen and was coated by TiO 2 nanoparticles, was also fabricated using the obtained emulsion as the templates. The emulsions displayed the highest stability near the isoelectric points of the TiO 2 nanoparticles, which was attributed to the van der Waals attraction between TiO 2 nanoparticles and oil droplets. Such mechanism was supported by a theoretical analysis based on calculation of the Hamaker constants and experimental evidences. Therefore, this work presents a simple, general and green method for preparing particle-stabilized emulsions. [ABSTRACT FROM AUTHOR]

he preparation and optoelectronic properties of WS2-MoS2 vertical heterostructure were mainly studied. Molybdenum oxide (MoO3), tungsten oxide (WO3) and sulfur powder (S) were employed as reactants, and then high quality WS2-MoS2 vertical heterostructures were prepared by using an improved one-step chemical vapor deposition method (CVD). Raman spectroscopy (Raman), photoluminescence spectroscopy (PL), optical microscope (OM), atomic force microscope (AFM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS) and other related devices were used to characterize the morphology and element composition of the heterostructures. At last, the photodetector based on WS2-MoS2 vertical heterostructure was produced, and the photoelectric characteristics of the fabricated device including the output characteristic curve, transfer characteristic curve and photocurrent curve were measured. The test results show that the photodetector based on WS2-MoS2 vertical heterostructure exhibits wonderful photoresponse characteristics under the 532 nm laser mode. It obviously means that the photodetector based on WS2-MoS2 vertical heterostructure can be applied to the preparation of high-efficiency optoelectronic devices and have broad application prospects in the field of microelectronics. [ABSTRACT FROM AUTHOR]