Solid Interaction Research Articles

Lighting up the structure and electronic properties of α-, β-, γ-Ag2WO4 polymorphs under laser irradiation: a DFT investigation.

Laser irradiation (LI)-matter interaction provides a versatile means to manipulate the physicochemical properties of materials. Understanding material responses to LI was the initial driving force for studying the effects of this interaction in solids, but the associated induced dynamics is hindered by the macroscopic number of particles interacting collectively with photonic modes. In this work, we conduct comprehensive theoretical calculations to gain insights into the changes in the lattice structure and electronic properties of α-, β-, γ-Ag2WO4 polymorphs induced by LI using density functional theory (DFT) calculations based on the electronic temperature (Te) within a two-temperature model (TTM) and ab initio molecular dynamics (AIMD) simulations. Overall, we reveal a clear visualization of how Te induces a structural and electronic transformation process during LI. The analysis of the evolution of the pair correlation function confirms that these polymorphs undergo a transition from crystalline to an amorphous structure under strong electronic excitations with concomitant formation of Ag nanoclusters. These results suggest the critical role that the Ag metallic nanoparticles may play in defining the behavior and properties of these materials. Our results offer physical insights into the thermodynamic stability and electronic properties of laser-irradiated Ag2WO4 polymorphs, which can inform on structural details currently inaccessible to experimental techniques. The presented approach is a versatile and sensitive tool for studying defect distribution and clustering processes in other functional Ag-based semiconductors.

Comparison of Indonesian students’ experiences in Japan and Indonesia: understanding global governance and self-efficacy in work readiness

ABSTRACT Globalization has intensified global interconnectedness and interdependence, demanding that higher education graduates possess global skills and knowledge. Internationalization of higher education aims to address these challenges. Students must understand global governance and develop a sense of global responsibility to participate effectively in international decision-making. Bandura’s Social Learning Theory (SLT) and Social Cognitive Theory (SCT) offer valuable insights into how students navigate internationalization. These theories suggest that students learn through observation and interaction with their environment, shaping their understanding of global citizenship and job readiness. This study compares the experiences of Indonesian students studying in International Programs at Universities in Japan and Indonesia, focusing on their understanding of global governance and self-efficacy in job readiness. Through qualitative interviews with 21 students, the research finds significant differences between the two countries’ approaches to internationalization. Students in Japan benefit from extensive global exposure through international internships and case studies, yet face challenges integrating with local Japanese communities, which affects their self-efficacy for adapting to local work environments. Conversely, Indonesian students gain valuable local engagement through the Kuliah Kerja Nyata (KKN) program, enhancing their ability to address local challenges despite limited global exposure. The discussion suggests that combining global solid exposure and local interaction can better prepare students for global and domestic job markets, making them more adaptable and competitive. These findings highlight the importance of balancing global and local experiences in internationalization strategies.

An immersed boundary formulation for lattice Boltzmann simulations of low-Reynolds fluid–structure interaction problems

Fluid–solid interaction problems are encountered in various natural phenomena and engineering applications. Specifically, when the fluid passes through a solid body, the resultant oscillatory forces may induce the structure to vibrate. In this work, the immersed boundary formulation has been implemented in the lattice Boltzmann approach to study complex fluid–structure interaction problems in a two-dimensional domain. The immersed boundary method has been used for its capability to describe complex geometries on a separate grid with respect to the one used to solve the fluid motion: a Eulerian one, fixed in the space, for the fluid domain, and a Lagrangian one, which can move freely to describe the body motion. The main advantage of using immersed boundary is the possibility to simulate the presence of a body through forces applied to the fluid domain, defining a discrete delta function necessary to distribute such forces. The presented approach has been applied to different Reynolds number flow conditions ranging from 20 up to 200 and different geometries starting from a plain cylinder. The validation results from the cylinder test case demonstrated excellent agreement with the literature, particularly in terms of drag and lift coefficients and the Strouhal number. The proposed algorithm captures significant high-frequency contributions arising from the interaction between vortices in the wake. Applications to both the cylinder-plate configuration and vibrating cylinder cases confirmed that this approach based on the weak fluid–structure interaction coupling can be effectively applied to a wide range of low Reynolds number scenarios.

Numerical Investigation of the Influence of Temperature on Fluidization Behavior: Importance of Particle Collision Parameters and Inter-Particle Forces

Fluidized bed reactors (FBRs) are integral to various industries due to their exceptional capability in facilitating efficient gas–solid interactions, resulting in superior mixing and heat and mass transfer. This research delves into the impact of temperature on fluidization dynamics, particularly focusing on the collisional properties of particles within the bed. The investigation builds upon foundational research, notably Geldart’s classification of fluidization regimes and recent advancements in high-temperature experimental techniques, such as High-Temperature Endoscopic-Laser particle image velocimetry/digital image analysis. To explore these temperature effects, a coupled Discrete Element Method and Computational Fluid Dynamics (cfd–dem) model was employed. This approach enables a detailed examination of gas–particle and particle–particle interactions under varying temperature conditions. The simulations in this study explore the friction coefficient, as well as changes in both tangential and normal restitution coefficients, which affect the fluidization behavior. These changes were systematically analyzed to determine their influence on minimum fluidization velocity and bubble formation. The numerical results are compared with experimental data from high-temperature fluidization studies, highlighting the necessity of incorporating inter-particle forces to fully capture the observed phenomena. The findings underscore the critical role of particle collisional properties in high-temperature fluidization and suggest the potential increasing role of inter-particle forces. Overall, this paper provides new insights into the complex dynamics of fluidized beds at elevated temperatures, emphasizing the need for further experimental–numerical research to enhance the reliability and understanding of these systems in industrial applications.

Three-Dimensional In Situ Stress Distribution in a Fault Fracture Reservoir, Linnan Sag, Bohai Bay Basin

The fault fracture body, consisting of faults, fracture zones, cracks, and the matrix, plays a crucial role in controlling oil and gas accumulation. Understanding its spatial distribution and analyzing the in situ stress field are essential for optimizing well design and fracturing operations. This study integrates geological, logging, and seismic data, and employs advanced techniques such as ant tracking to establish a skeletal model of the fault fracture body. Reverse modeling and optimization reconstruction are used to construct a three-dimensional geomechanical model of the fracture system. Machine learning techniques, specifically a back propagation (BP) neural network, are utilized to invert the boundary conditions of the study area. Finite element numerical simulation software is then applied to model the three-dimensional in situ stress field under coupled flow–solid interaction. The reservoirs in the study area are characterized by a dense structure, low porosity, and low permeability. The results indicate that the maximum horizontal principal stress in the fault fracture reservoir ranges from 68.0 to 72.8 MPa, while the minimum horizontal principal stress ranges from 58.2 to 63.1 MPa. The stress at fractures is lower than that in the surrounding matrix, and stress concentrations occur at both ends of the faults. The in situ stress field exhibits distinct subarea characteristics, with significant stress reductions across fault fractures and directional deflections at faults. These findings provide valuable insights for improving reservoir development efficiency and optimizing well operations in similar geological settings.

Performance evaluation of large-size tilting-pad thrust bearings based on results from small-size models

Large hydrodynamic tilting-pad thrust bearings can exceed diameters of 5 meters, which makes them difficult to test experimentally, which is important in the case of new designs. Therefore, smaller test bearings should be used to fulfil the demand for experimental verification. However, due to the complexity of thermal and flow phenomena, the choice of parameters in scaled tests is not obvious. In this paper dimensional analysis was used to determine the parameters that account for all relevant phenomena in the full-size bearing. As a result of the rigorous use of dimensional analysis, a set of scaling factors was determined. Calculations using an advanced Fluid Solid Interaction (FSI) model showed that the results for a large bearing and its scaled model perfectly agree. However, in the practical planning of the experiments, some parameters after appropriate scaling would be challenging to obtain – e.g., material properties. Next, it was checked if a more liberal approach, namely, leaving some less important parameters without proper scaling, would still allow for a good agreement of the results between a large bearing and a scaled model. The results showed, however, that all parameters have a great influence on the results. Without rigorous application of the dimensional analysis, the similarity between a large bearing and its scaled model is not obtained. The authors recommend that only rigorous dimensional analysis yields proper results. Experiments on small bearings should rather be used to verify theoretical calculation models and it seems impossible to carry out properly scaled experiments.

Effects of Vibration-Reducible Cementitious Materials on the Acoustic and Structural Responses of Buildings Adjacent to Urban Railway Systems: A Numerical Approach

Some studies have developed different kinds of vibration-reducible construction materials. However, no existing study has applied these materials in a building to prove their effectiveness at a structural level. Besides, much of the related research has focused only on measuring sound pressure or vibration levels within buildings adjacent to railway systems. Although some studies have provided methods to predict the vibration of a building structure, they cannot determine the train-induced sound pressure level simultaneously. Therefore, this study used the finite element model to simulate an existing building structure to prove the effectiveness of this method. Based on the combination of the acoustic and solid interaction modules in the finite element analysis method, the vibration and sound levels of buildings based on different kinds of vibration-reducible cementitious materials were estimated using different models. The results show that vibration-reducible cementitious materials can reduce vibration velocity and sound pressure levels by up to 7.1 dB and 5.2 dB with an increased floor height, respectively. In addition, reduced vibration can decrease structure-borne noise by up to 2.9 dB. A further parametric study shows that cementitious materials with a relatively high elastic modulus, a high damping loss factor, and low density can be effective for vibration and sound reduction.

Mechanical–chemical coupling in gas–surface interaction: A study of strain effects on the catalytic properties of SiO2

In actual flight conditions, the surface of thermal protection materials may experience stress, and the impact of surface strain on catalytic reaction and mechanical–chemical coupling has not been fully explored. In this study, a surface gas–solid interaction model was constructed using reaction molecular dynamics and density functional theory methods. The surface catalytic reaction characteristics of α-SiO2 (001) under up to 2% uniaxial and biaxial tensile strain were investigated. Results indicate that both uniaxial stretching along the X axis and biaxial stretching along the X and Y axes inhibit the catalytic recombination reaction at higher surface temperatures. For the uniaxial stretching model, when the strain reaches 2%, the catalytic coefficient decreases by 21.2%, whereas for the biaxial stretching model, it decreases by 34.3%. From the perspectives of surface morphology and energy, the study reveals that tensile strain reduces the undercoordination degree of Si atoms on the surface, reduces the surface energy of α-SiO2 (001), increases the activation energy of the atomic oxygen recombination reaction, alters the recombination pathways of oxygen atoms, strain-induced selective desorption of oxygen atoms reduces the recombination probabilities of both Eley–Rideal and Langmuir–Hinshelwood pathways, ultimately decreasing the catalytic recombination coefficient.

Fluid–structure interaction characteristics between stator–rotor clearance flow and rotor of full tubular pump

Affected by the hydrodynamic pressure difference between the inlet and outlet side of the impeller of a full tubular pump (FTP), stator–rotor clearance flow inevitably exists during the operation of FTP, disturbing the flow field and causing hydraulic friction around the rotor. Based on the fluid–solid interaction method, this paper explored the interaction characteristics between the flow field of the stator–rotor clearance flow and the rotor structure. By conducting numerical simulation and model test, the deformation and stress distribution characteristics of the rotor were investigated and its high-strength stress region was located, where the alteration mechanism of the stator–rotor clearance vortex and the spatiotemporal distribution of velocity field were further deduced. The results show that during the operation of FTP, the maximum deformation region of the rotor was concentrated in the outer ring which showed obvious periodicity and the peak equivalent stress of the rotor was distributed along the bone line of the impeller with the span of 0.1. With the widening of spacing between the stator and the rotor, the accumulation of high momentum fluid both near the stator wall and the rotor wall was increased, and the radial non-uniformity of the clearance flow circulation was aggravated so that part of the mainstream water in the intersection domain deflected inward, magnifying the blade stress and leading to the peak deformation surface of the rotor twirling along the direction of impeller rotation at the speed of 8°/mm. This study investigated the fluid–structure interaction features of FTP, providing reference for future research on performance optimization.

Toward Multi-Dimensional Separation of Nanoparticles in Tubular Centrifuges

The processing and preparation of particulate products is an important process in modern industry and science. The enormous potential for innovation in research and development is due to the complex interactions of solids with their environment. The aim of advanced particle production is to achieve high yields of narrowly distributed particle sizes, shapes or material compositions that provide advantageous product specifications. The integration of solid–liquid separation into these processes expands the process engineering scope in terms of product quality and efficiency. Designing these processes to accommodate a wide range of separation characteristics at small-particle-size scales is a major challenge. Taking these aspects into account, the present work aims to improve a dynamic simulation tool for tubular centrifuges that models the time- and space-dependent mass transport and thus, for the first time, can predict separation outcomes when processing both single- and multi-component systems. Utilizing an optical measurement technique, nanosuspension properties can be measured in real time during separation to support model validation. The simulation results align closely with experimental findings and offer plausible insights when addressing multi-dimensional property distributions of non-spherical particles. This study contributes to advanced modeling of separation experiments in tubular centrifuges in real time, taking into account multiple particle properties such as material density and particle form.

Dual-Asymmetric Solid Additive Enables Eco-friendly All-Polymer Solar Cells with Over 19 % Efficiency and Excellent Stability.

The optimization of morphology in all-polymer solar cells (all-PSCs) often relies on the use of solvent additives. However, their tendency to remain trapped in the device due to high boiling points leads to performance degradation over time. In this study, we introduce a novel approach involving the design and synthesis of one dual-asymmetric solid additive featuring mono-brominated-asymmetric dithienothiophene (SL-1). Leveraging the synergistic effects of asymmetric substitution and core structures, fine-tuning the molecule dipole moment enhancing solid additive interactions with host materials, thereby regulating polymer aggregation and influencing blend morphology during device fabrication. This results in highly ordered π-π stacking and a favorable phase-separated morphology within all-polymer active layer. Our work achieved a record efficiency of 19.19 % in eco-friendly all-PSCs, significantly outperforming SL-0 (18.37 %) and SL-2 (16.60 %), both featuring an asymmetric core. Furthermore, SL-1-treated all-PSCs retain over 90 % of their initial efficiency after 2140 hours of operation, with an extrapolated T80 lifetime reaching 12400 hours. This represents a significant improvement in stability compared to devices treated with solvent additive (1-CN), which typically exhibits a T90 lifetime of 700 hours. Our findings underscore the efficacy of utilizing dual-asymmetric solid additives as a straightforward and viable strategy for optimizing all-polymer morphology. SL-1 represents a promising advancement towards eco-friendly fabrication and application of high-efficiency and stable all-PSCs.

Theoretical Study of the Pre-Plasma Density Scale Length’s Influence on the Absorption Efficiency in Laser–Solid Interaction at Relativistic Laser Intensities for PW-Class Lasers

This work studied the pre-plasma that builds up in interactions of focused high-power PW-class lasers with solid targets at the target surface facing the laser beam, and its impact on the global laser absorption efficiency as well as on the spectral cut-off energy of laser-generated proton beams. Our practical heuristic estimates were derived from the example of the VEGA-3 laser at CLPU. Our modeling results for the pre-plasma expansion due to the laser pedestal of VEGA-3 were benchmarked by hydrodynamic simulations, revealing good agreement for the evolution before the arrival of the main Gaussian laser intensity peak. Our detailed numerical two-dimensional Particle-in-Cell simulations showed the impact of different pre-plasma scale lengths on the absorption efficiency of laser energy into electrons, relevant for the seeding of other types of radiation. It was shown that the absorption can increase manyfold when increasing the pre-plasma scale length. This effect can be beneficial for the spectral cut-off energy of accelerated protons, where a trade-off between absorption and electron dynamics yields an optimum pre-plasma scale length. The findings can be applied to other PW-class laser facilities.

Exploring the antifungal potential of Cannabis sativa-derived stilbenoids and cannabinoids against novel targets through in silico protein interaction profiling.

Cannabinoid and stilbenoid compounds derived from Cannabis sativa were screened against eight specific fungal protein targets to identify potential antifungal agents. The proteins investigated included Glycosylphosphatidylinositol (GPI), Enolase, Mannitol-2-dehydrogenase, GMP synthase, Dihydroorotate dehydrogenase (DHODH), Heat shock protein 90 homolog (Hsp90), Chitin Synthase 2 (CaChs2), and Mannitol-1-phosphate 5-dehydrogenase (M1P5DH), all of which play crucial roles in fungal survival and pathogenicity. This research evaluates the binding affinities and interaction profiles of selected cannabinoids and stilbenoids with these eight proteins using molecular docking and molecular dynamics simulations. The ligands with the highest binding affinities were identified, and their pharmacokinetic profiles were analyzed using ADMET analysis. The results indicate that GMP synthase exhibited the highest binding affinity with Cannabistilbene I (-9.1kcal/mol), suggesting hydrophobic solid interactions and multiple hydrogen bonds. Similarly, Chitin Synthase 2 demonstrated significant binding with Cannabistilbene I (-9.1kcal/mol). In contrast, ligands such as Cannabinolic acid and 8-hydroxycannabinolic acid exhibited moderate binding affinities, underscoring the variability in interaction strengths among different proteins. Despite promising in silico results, experimental validation is necessary to confirm therapeutic potential. This research lays a crucial foundation for future studies, emphasizing the importance of evaluating binding affinities, pharmacokinetic properties, and multi-target interactions to identify promising antifungal agents.

Research Progress on Nano-Confinement Effects in Unconventional Oil and Gas Energy—With a Major Focus on Shale Reservoirs

Compared to conventional reservoirs, the abundant nanopores developed in unconventional oil and gas reservoirs influence fluid properties, with nano-confinement effects. The phase behavior, flow characteristics, and solid–liquid interactions of fluids are different from those in conventional reservoirs. This review investigates the physical experiments, numerical simulations, and theoretical calculation methods used in the study of nano-confinement effects in unconventional oil and gas energy. The impact of different methods used in the analysis of fluid phase behavior and movement in nanopores is analyzed. Nanofluidic, Monte Carlo method, and modified equation of state are commonly used to study changes in fluid phase behavior. Nano-confinement effects become significant when pore sizes are below 10 nm, generally leading to a reduction in the fluid’s critical parameters. The molecular dynamic simulation, Monte Carlo, and lattice Boltzmann methods are commonly used to study fluid movement. The diffusion rate of fluids decreases as nanopore confinement increases, and the permeability of nanoscale pores is not only an inherent property of the rock but is also influenced by pressure and fluid–solid interactions. In the future, it will be essential to combine various research methods, achieve progress in small-scale experimental analysis and multiscale simulation.

Enantiomeric C-6 fluorinated swainsonine derivatives as highly selective and potent inhibitors of α-mannosidase and α-l-rhamnosidase: design, synthesis and structure-activity relationship study

Enantiomeric C-6 fluorinated swainsonine derivatives as highly selective and potent inhibitors of α-mannosidase and α-l-rhamnosidase: design, synthesis and structure-activity relationship study

Pivotal role of solid phase interactions in the pressure-induced bi-stability of cyanide-bridged Fe2Co2 square complexes

Pressure-sensitive (Fe–CN–Co) molecular switches can be obtained by controlling the crystallization temperature. Here, an intriguing conversion from FeIII–CoII to FeII–CoIII and back to FeIII–CoII upon increasing pressure at 200 K is rationalized.

Challenges in blood fractionation for cancer liquid biopsy: how can microfluidics assist?

Liquid biopsy provides a minimally invasive approach to characterise the molecular and phenotypic characteristics of a patient's individual tumour by detecting evidence of cancerous change in readily available body fluids, usually the blood. When applied at multiple points during the disease journey, it can be used to monitor a patient's response to treatment and to personalise clinical management based on changes in disease burden and molecular findings. Traditional liquid biopsy approaches such as quantitative PCR, have tended to look at only a few biomarkers, and are aimed at early detection of disease or disease relapse using predefined markers. With advances in the next generation sequencing (NGS) and single-cell genomics, simultaneous analysis of both circulating tumour DNA (ctDNA) and circulating tumour cells (CTCs) is now a real possibility. To realise this, however, we need to overcome issues with current blood collection and fractionation processes. These include overcoming the need to add a preservative to the collection tube or the need to rapidly send blood tubes to a centralised processing lab with the infrastructure required to fractionate and process the blood samples. This review focuses on outlining the current state of liquid biopsy and how microfluidic blood fractionation tools can be used in cancer liquid biopsy. We describe microfluidic devices that can separate plasma for ctDNA analysis, and devices that are important in isolating the cellular component(s) in liquid biopsy, i.e., individual CTCs and CTC clusters. To facilitate a better understanding of these devices, we propose a new categorisation system based on how these devices operate. The three categories being 1) solid Interaction devices, 2) fluid Interaction devices and 3) external force/active devices. Finally, we conclude that whilst some assays and some cancers are well suited to current microfluidic techniques, new tools are necessary to support broader, clinically relevant multiomic workflows in cancer liquid biopsy.

Mechanical Properties of Faecal Sludge and Its Influence on Moisture Retention

The mechanical properties of faecal sludge (FS) influence its moisture retention characteristics to a greater extent than other properties. A comprehensive fundamental characterisation of the mechanical properties is scarcely discussed in the literature. This research focused on bulk and true densities, porosity, particle size distribution and zeta-potential, extracellular polymeric substances, rheology and dilatancy, microstructure analysis, and compactibility in the context of using the FS as a substitute for soil in land reclamation and bioremediation processes. FSs from different on-site sanitation systems were collected from around Durban, South Africa. The porosity of the FSs varied between 42% and 63%, with the zeta-potential being negative, below 10 mV. Over 95% of the particles were <1000 µm. With its presence in the inner part of the solid particles, tightly bound extra-cellular polymeric substances (TB-EPSs) influenced the stability of the sludge by tightly attaching to the cell walls, with the highest being in the septic tank with the greywater sample. More proteins than carbohydrates also confirmed characterised the anaerobic nature of the sludge. The results of the textural properties using a penetrometer showed that the initial slope of the positive part of the penetration curve was related to the stiffness of the sludge sample and similar to that of sewage sludge. The dynamic oscillatory measurements exhibited a firm gel-like behaviour with a linear viscoelastic behaviour of the sludges due to the change in EPSs because of anaerobicity. The high-TS samples exhibited the role of moisture as a lubricating agent on the motion of solid particles, leading to dilatancy with reduced moisture, where the yield stress was no longer associated with the viscous forces but with the frictional contacts of solid–solid particle interactions. The filtration–compression cell test showed good compactibility, but the presence of unbound moisture even at a high pressure of 300 kPa meant that not all unbound moisture was easily removable. The moisture retention behaviour of FS was influenced by its mechanical properties, and any interventional changes to these properties can result in the release of the bound moisture of FS.

Combining CFD and AI/ML Modeling to Improve the Performance of Polypropylene Fluidized Bed Reactors

Polypropylene is one of the most widely used polymers in various applications, ranging from packaging materials to automotive components. This paper proposes the Computational Fluid Dynamics (CFD) and AI/ML simulation of a polypropylene fluidized bed reactor to reduce reactor loss and facilitate process understanding. COMSOL Multiphysics 6.2® solves a 2D multiphase CFD model for the reactor’s complex gas–solid interactions and fluid flows. The model is compared to experimental results and shows excellent predictions of gas distribution, fluid velocity, and temperature gradients. Critical operating parameters like feed temperature, catalyst feed rate, and propylene inlet concentration are all tested to determine their impact on the single-pass conversion of the reactor. The simulation simulates their effects on polypropylene yield and reactor efficiency. It also combines CFD with artificial intelligence and machine learning (AI/ML) algorithms, like artificial neural networks (ANN), resulting in a powerful predictive tool for accurately predicting reactor metrics based on operating conditions. The multifaceted CFD-AI/ML tool provides deep insight into improving reactor design, and it also helps save computing time and resources, giving industrial polypropylene plant growth a considerable lift.

Crystal structure solid interaction products of ε-caprolactam with hydrofluoric asid and copper(II) hexafluorosilicate

Crystal structure solid interaction products of ε-caprolactam with hydrofluoric asid and copper(II) hexafluorosilicate