Abstract Miniaturized functional fluidic pumps have found broad applications across various fields; however, the fabrication and dimensional limitations of their electrodes remain a significant challenge. Conventional manufacturing techniques often fail to achieve high aspect ratio structures exceeding 2 and electrode heights greater than 1 mm. In this work, we propose a novel extreme microfabrication strategy that integrates flexible molding techniques with advanced microfabrication processes to develop high‐precision pump electrodes. These electrodes are successfully implemented in droplet manipulation applications. First, we selected suitable microfabrication‐compatible materials and developed a conductive, flexible liquid elastomer, along with a tailored fabrication process. Next, a functional working fluid compatible with the electrodes was synthesized and characterized in terms of its viscosity, electrical conductivity, dielectric constant, and interfacial behavior with aqueous phases. A corresponding microfluidic chip was also fabricated to assess its droplet generation performance. Both duty cycle‐based and frequency‐based droplet manipulation strategies were investigated using this chip. Finally, a machine learning approach was employed to model the droplet generation process and evaluate the influence of four key parameters on device performance. This study establishes a foundational platform and design pathway for future development of integrated on‐chip pumping systems in microfluidic applications.
Background Musculoskeletal disorders (MSDs) are a significant health concern in the workplace, and while ergonomic interventions are commonly used, their long-term effectiveness is often questioned. Serious games (SGs), designed to go beyond entertainment, have emerged as a promising tool that may address some of the limitations of traditional interventions, such as the need for sustained impact and greater worker engagement. Objective This review aims to identify and analyze the key characteristics of SGs—including design, gameplay, and expected outcomes—that have been developed for the prevention or mitigation of work-related MSDs. Additionally, it explores the documented effects of SG implementation, assessing their potential contribution to MSD prevention and intervention strategies. Methods A scoping review was conducted across 6 scientific databases (APA PsycInfo, Web of Science, Science Direct, MEDLINE, IEEE Xplore, and Google Scholar) to identify relevant studies published up to 2025. The selection process involved a multistep screening, including title and abstract review, followed by full-text assessment by 2 independent reviewers. Studies included were original research articles in English addressing MSD prevention and mitigation. Exclusions applied to studies on nonwork-related MSDs, limited content, duplicates, or repurposed entertainment games or gamification solutions. Data extraction was performed using a standardized form to capture key study characteristics. A 2-level analysis was applied: descriptive analysis, categorizing studies based on study characteristics and primary focus (design, evaluation, or both), and content-based analysis, examining game design, gameplay, expected outcomes, and evaluation methods to provide a structured synthesis of findings. Results The initial search identified 2700 records, with 15 studies meeting the inclusion criteria. These studies explored diverse applications of SGs for MSD prevention, focusing either on game design and development or on educational impact assessment. Notably, only 2 studies comprehensively addressed both design methodology and educational evaluation. Findings revealed considerable variability in design approaches, technological platforms, gameplay mechanics, and expected outcomes. Additionally, the literature exhibited significant inconsistencies in evaluating SG effectiveness, with methodological limitations affecting comparability. While some studies targeted rehabilitation or occupational health and safety, only a few explicitly focused on MSD prevention, with a predominant emphasis on physical risk factors, whereas psychosocial and organizational aspects remained largely underexplored. Conclusions This review highlights the need for standardized protocols and criteria for the design and evaluation of SGs to enable further synthesis and impact measurement. The integration of MSD prevention into SGs remains limited and is often approached indirectly through related themes such as workplace safety or rehabilitation. Future research should focus on developing and validating more comprehensive SG-based interventions and exploring their potential as effective tools in occupational health. The findings indicate a substantial gap in empirical evidence regarding the effectiveness of SGs for MSD prevention, largely due to the disparity in experimental approaches.
Anders Frederiksen, Mandus Aldag, I. Solov’yov
et al.
Simple Summary The Atlantic herring is one of many migratory fish that may use the geomagnetic field to navigate on its annual migration. The exact mechanism used for detecting the geomagnetic field in fish is still an open discussion, and the two main theories on magnetic sensing in animals are in the main focus: magnetite-based or radical pair-based. Here, we explore whether the cryptochrome 4 protein of fish would be able to carry out the necessary electron transfer activation to create a radical pair to be used for magnetic sensing. Abstract Marine fish migrate long distances up to hundreds or even thousands of kilometers for various reasons that include seasonal dependencies, feeding, or reproduction. The ability to perceive the geomagnetic field, called magnetoreception, is one of the many mechanisms allowing some fish to navigate reliably in the aquatic realm. While it is believed that the photoreceptor protein cryptochrome 4 (Cry4) is the key component for the radical pair-based magnetoreception mechanism in night migratory songbirds, the Cry4 mechanism in fish is still largely unexplored. The present study aims to investigate properties of the fish Cry4 protein in order to understand the potential involvement in a radical pair-based magnetoreception. Specifically, a computationally reconstructed atomistic model of Cry4 from the Atlantic herring (Clupea harengus) was studied employing classical molecular dynamics (MD) and quantum mechanics/molecular mechanics (QM/MM) methods to investigate internal electron transfers and the radical pair formation. The QM/MM simulations reveal that electron transfers occur similarly to those found experimentally and computationally in Cry4 from European robin (Erithacus rubecula). It is therefore plausible that the investigated Atlantic herring Cry4 has the physical and chemical properties to form radical pairs that in turn could provide fish with a radical pair-based magnetic field compass sensor.
Abstract Varying the chemical consistency of acoustically levitated droplets opens up an in situ study of chemical and biochemical reactions in small volumes. However, the optimization of the mixing time and the minimization of the positional instability induced by solution dispensing are necessary for practical applications such as the study of the transient state of macromolecules crystallography during the ligand binding processes. For this purpose, we study the inertial mixing in a configuration compatible with the room‐temperature crystallography using the acoustic levitation diffractometer, therein solution drops ejected at high velocity collide and coalesce with droplets dispensed on acoustically levitated and rotating polymer thin‐film sample holders. With the proposed method, we are able to achieve the mixing time of ∼0.1 s for sub‐micro and a few microliter droplets. The observed short mixing time is ascribed to the rapid penetration of the solution into the droplets and confirmed by a computational fluid dynamic simulation. The demonstrated accelerated solution mixing is tested in a pilot time‐lapse protein crystallography experiment using the acoustic levitation diffractometer. The results indicate the detection of transient ligand binding state within 2 s after the solution dispensing, suggesting the feasibility of the proposed method for studying slow biochemical processes.
Derik W. Gryczak, Ervin K. Lenzi, Michely P. Rosseto
et al.
We investigate the diffusion phenomenon of particles in the vicinity of a spherical colloidal particle where particles may be adsorbed/desorbed and react on the surface of the colloidal particle. The mathematical model comprises a generalized diffusion equation to govern bulk dynamics and kinetic equations which can describe non-Debye relaxations and is used for the colloid’s surface. For the reaction processes, we also consider the presence of convolution kernels, which offer the flexibility of describing a single process or process with intermediate reactions before forming the final species. Our analysis focuses on analytical and numerical calculations to obtain the particles’ behavior on the colloidal particle’s surface and to determine how it affects the diffusion of particles around it. The solutions obtained show various behaviors that can be connected to anomalous diffusion phenomena and may be used to describe the ever-richer science of colloidal particles better.
Thermodynamics, Descriptive and experimental mechanics
Linear relationships, expressing the electrochemical properties of molecules as functions of structure, give insight into the associated electrochemical process and are a tool for prediction. Many biological activities rely on water-based dissociation, making electrochemical properties a bridge between structure and activity. Motivated by a previous study, a replica is made here on a different dataset in order to validate/invalidate the previously reported results. There are several methods for obtaining structure-based descriptors. Some of the methods have been devised to account for molecular topology, some to account for molecular geometry, and others to account for both. Two methods are involved here to derive structure-based descriptors and further obtain structure–property relationships (FMPI and ChPE). In order to express structure descriptors, both FMPI and ChPE express first the topology of the molecule, using the heavy atoms identity matrix and the heavy atoms adjacency matrix, both square symmetric matrices in the belief that symmetry is one major factor of molecular stability. A set of 2,6-dimethyl-1,4-dihydropyridine derivatives with oxidation peak potentials and coulometrically determined number of electrons experimental data is subjected to the search for structure–activity relationships. Even if the 2,6-dimethyl-1,4-dihydropyridine is a symmetric compound (of Cs point group), their derivatives are generally not symmetric (9 out of 24 are asymmetric). The dataset is subjected to descriptive and inferential statistics in order to filter out the most relevant structure–activity relationship. The geometry is built using three levels of theory (one from molecular mechanics and two others from density functionals, of which one accounts for the interaction with water as solvent). One challenge of picking one out of two reported measured values is dealt with by calculating the likelihood associated with the two choices. Relevant structure–activity models are extracted and discussed. The use of in vivo (in water, SM8 model) models in geometry optimization (from MMFF94 and B3LYP and to M06 + Water SM8) results in a precision gain, but this is, in most of the cases, not statistically significant, and this can be considered a negative result.
Accurate evaluation of thermo-fluid dynamic characteristics in tanks is critically important for designing liquid hydrogen tanks for small-scale hydrogen liquefiers to minimize heat leakage into the liquid and ullage. Due to the high costs, most future liquid hydrogen storage tank designs will have to rely on predictive computational models for minimizing pressurization and heat leakage. Therefore, in this study, to improve the storage efficiency of a small-scale hydrogen liquefier, a three-dimensional CFD model that can predict the boil-off rate and the thermo-fluid characteristics due to heat penetration has been developed. The prediction performance and accuracy of the CFD model was validated based on comparisons between its results and previous experimental data, and a good agreement was obtained. To evaluate the insulation performance of polyurethane foam with three different insulation thicknesses, the pressure changes and thermo-fluid characteristics in a partially liquid hydrogen tank, subject to fixed ambient temperature and wind velocity, were investigated numerically. It was confirmed that the numerical simulation results well describe not only the temporal variations in the thermal gradient due to coupling between the buoyance and convection, but also the buoyancy-driven turbulent flow characteristics inside liquid hydrogen storage tanks with different insulation thicknesses. In the future, the numerical model developed in this study will be used for optimizing the insulation systems of storage tanks for small-scale hydrogen liquefiers, which is a cost-effective and highly efficient approach.
Thermodynamics, Descriptive and experimental mechanics
Charles Brissot, Léa Cailly-Brandstäter, Elie Hachem
et al.
The integration of phase change phenomena through an interface is a numerical challenge that requires proper attention. Solutions to properly ensure mass and energy conservation were developed for finite difference and finite volume methods, but not for Finite Element methods. We propose a Finite Element phase change model based on an Eulerian framework with a Continuous Surface Force (CSF) approach. It handles both momentum and energy conservation at the interface for anisotropic meshes in a light an efficient way. To do so, a model based on the Level Set method is developed. A thick interface is considered to fit with the CSF approach. To properly compute the energy conservation, heat fluxes are extended through this interface thanks to the resolution of a transport equation. A dedicated pseudo compressible Navier–Stokes solver is added to compute velocity jumps with a source term at the interface in the velocity divergence equation. Several 1D and 2D benchmarks are considered with increasing complexity to highlight the performances of each feature of the framework. This stresses the capacity of the model to properly tackle phase change problems.
Thermodynamics, Descriptive and experimental mechanics
The equivalence between parabolic transport equations for solute concentrations and stochastic dynamics for solute particle motion represents one of the most fertile correspondences in statistical physics originating from the work by Einstein on Brownian motion. In this article, we analyze the problems and the peculiarities of the stochastic equations of motion in microfluidic confined systems. The presence of solid boundaries leads to tensorial hydrodynamic coefficients (hydrodynamic resistance matrix) that depend also on the particle position. Singularity issues, originating from the non-integrable divergence of the entries of the resistance matrix near a solid no-slip boundary, determine some mass-transport paradoxes whenever surface phenomena, such as surface chemical reactions at the walls, are considered. These problems can be overcome by considering the occurrence of non vanishing slippage. Added-mass effects and the influence of fluid inertia in confined geometries are also briefly addressed.
Thermodynamics, Descriptive and experimental mechanics
We develop the theory of transient electrophoresis of a weakly charged, infinitely long cylindrical colloidal particle under an application of a transverse or tangential step electric field. Transient electrophoretic mobility approaches steady electrophoretic mobility with time. We derive closed-form expressions for the transient electrophoretic mobility of a cylinder without involving numerical inverse Laplace transformations and the corresponding time-dependent transient Henry functions. The transient electrophoretic mobility of an arbitrarily oriented cylinder is also derived. It is shown that in contrast to the case of steady electrophoresis, the transient Henry function of an arbitrarily oriented cylinder at a finite time is significantly smaller than that of a sphere with the same radius and mass density as the cylinder so that a cylinder requires a much longer time to reach its steady mobility than the corresponding sphere.
Thermodynamics, Descriptive and experimental mechanics
Nurlybek Kasimov, Eric Dymkoski, Giuliano De Stefano
et al.
This work extends the characteristic-based volume penalization method, originally developed and demonstrated for compressible subsonic viscous flows in (J. Comput. Phys. 262, 2014), to a hyperbolic system of partial differential equations involving complex domains with moving boundaries. The proposed methodology is shown to be Galilean-invariant and can be used to impose either homogeneous or inhomogeneous Dirichlet, Neumann, and Robin type boundary conditions on immersed boundaries. Both integrated and non-integrated variables can be treated in a systematic manner that parallels the prescription of exact boundary conditions with the approximation error rigorously controlled through an a priori penalization parameter. The proposed approach is well suited for use with adaptive mesh refinement, which allows adequate resolution of the geometry without over-resolving flow structures and minimizing the number of grid points inside the solid obstacle. The extended Galilean-invariant characteristic-based volume penalization method, while being generally applicable to both compressible Navier–Stokes and Euler equations across all speed regimes, is demonstrated for a number of supersonic benchmark flows around both stationary and moving obstacles of arbitrary shape.
Thermodynamics, Descriptive and experimental mechanics
This article discusses the possibility of further reducing the mass of the heat exchanger with stainless steel star-shaped fins while achieving good heat transfer performance. For this purpose, we perforated the fins with holes Ø2, Ø3, and Ø4 mm. Applying computational fluid dynamics (CFD) numerical analysis, we determined the influence of each perforation on the characteristics of the flow field in the liquid–gas type of heat exchanger and the heat transfer for the range of <i>Re</i> numbers from 2300 to 16,000. With a reduction in the mass of the fins to 17.65% (by Ø4 mm), perforated fins had greater heat transfer from 5.5% to 11.3% than fins without perforation. A comparison of perforated star-shaped fins with annular fins was also performed. Perforated fins had 51.8% less mass than annular fins, with an increase in heat transfer up to 26.5% in terms of Nusselt number.
Thermodynamics, Descriptive and experimental mechanics
Subjects related to fluid mechanics for hydraulic engineers ought to be delivered in interesting and active modes. New methods should be introduced to improve the learning students’ abilities in the different courses of the Bachelor’s and Master’s degree. Related to active learning methods, a continuous project-based learning experience is described in this research. This manuscript shows the developed learning methodology, which was included on different levels at Universitat Politècnica de València. The main research goal is to show the active learning methods used to evaluate both skills competences (e.g., “Design and Project”) and specific competences of the students. The research shows a particular developed innovation teaching project, which was developed by lecturers and professors of the Hydraulic Engineering Department, since 2016. This project proposed coordination in different subjects that were taught in different courses of the Bachelor’s and Master’s degrees, in which 2200 students participated. This coordination improved the acquisition of the learning results, as well as the new teaching methods increased the student’s satisfaction index.
Thermodynamics, Descriptive and experimental mechanics
Yuri Abrashkevych, Grygory Machyshyn, Alexander Marchenko
et al.
With every passing year, the flexible abrasive tool is increasingly used. It is used in the cleaning of metal and non-metal surfaces from paint coatings, rust and all kinds of impurities.
The purpose of the work is to study the process of oscillation of the elastic fiber during its stationary rotation. The result of the work will determine the life of the polymer-abrasive brush.
Using the theoretical method, the following studies were performed: using the D'Alembert principle, the fiber element equilibrium was investigated; the components of the intensity of the total inertial load acting on the element of the rod during its rotation were determined; describes the relative interconnected bends of longitudinal oscillations of the cantilever rod of the rotor during its stationary rotation.
The results of the performed work allow to continue the study of oscillations of polymer-abrasive fibers with horizontal arrangement of the brush disk. This will determine the resource of the working body.
The uniform distribution of abrasive grains of the same mass and size over the entire length and in section of the fibers allows to reduce the frequency of bending oscillations. This increases the brush workforce. As fatigue stresses decrease.
The results of the work can be used to investigate the resource of flexible abrasive working bodies. Which are becoming widespread in modern times.
A new method determining the equivalent dynamic parameters such as stiffness, vibrating mass, and air damping factor in motion direction of shuttle (i.e. in y-direction) is proposed, thence the differential motion equation of shuttle is established and solved to achieve a typical displacement formula. Simulation and experimental results show that the change of ELCA' displacement is inappreciable while the range of driving frequency up to 27 Hz (error of 10% with driving voltage is a square wave). Moreover, the range of driving frequency for the ELCA can be extended up to 1 kHz with displacement amplitude error of 10% while the shape of driving voltage is a harmonic sine wave.
Mechanical engineering and machinery, Descriptive and experimental mechanics
The paper proposes an algorithm to solve a general Duffing equation, in which a process of transforming the initial equation to a resulting equation is proposed, and then the coupling successive approximation method is applied to solve the resulting equation. By using this algorithm a special physical factor and complex-valued solutions to the general Duffing equation are revealed. The proposed algorithm does not use any assumption of small parameters in the equation solving. The coupling successive procedure provides an analytic approximated solution in both real-valued or complex-valued solution. The procedure also reveals a formula to evaluate the vibration frequency, \(\varphi\), of the non-linear equation. Since the first approximation solution is in a closed-form, the chaos index of the general Duffing equation and the chaotic characteristics of solutions can be predicted. Some examples are used to illustrate the proposed method. In the case of chaotic solution, the Pointcaré conjecture is used for solution verification.
Mechanical engineering and machinery, Descriptive and experimental mechanics
Yajaira Alvarado, J. Quintero, Xavier José Pírela Alvarado
et al.
El presente articulo tiene como objetivo determinar los parametros fundamentales que generen una metodologia pertinente para la insercion de las practicas en el laboratorio tecnico de diseno mecanico de la Universidad del Zulia Nucleo Costa Oriental del Lago. El estudio es descriptivo transeccional con un diseno de campo no experimental. El instrumento de recoleccion de datos fue el cuestionario. La poblacion estuvo conformada por 10 profesores que administran academicamente las unidades curriculares adscritas en el area de diseno mecanico. Por ser una poblacion finita se empleo el censo poblacional. Los resultados determinaron la necesidad de disenar una serie de practicas relacionadas con: Mecanica de Solidos, Elementos de Maquinas, Dinamica, Estatica y Mecanica de Maquinas, con lo cual exista una conexion entre lo establecido en el plan curricular de La Universidad del Zulia (LUZ) y el proyecto del laboratorio tecnico del Nucleo; de tal forma que el estudiante sea preparado como un individuo integral, capaz de desenvolverse dentro de una sociedad del conocimiento enmarcada en el fenomeno de la globalizacion, en pro de una formacion integral ajustada al desarrollo de competencias especificas como lo establece la nueva resolucion del Ministerio de Educacion Superior de Venezuela, a fin de que el egresado se relacione, directamente, con el sector productivo. This article aims to determine the basic parameters to generate an appropriate methodology for the integration of technical laboratory practices in the mechanical design of the Universidad Del Zulia Nucleo Costa Oriental del Lago. The study is descriptive trans with a non-experimental field design. The data collection instrument was the questionnaire. The population consisted of 10 teachers who manage academic curriculum units assigned in the area of mechanical design. As a finite population census was used. The results determined the need to design a set of practices related to: Solid Mechanics, Machine Elements, Dynamics, Statics and Mechanics of machines, thus there is a connection between what is established in the curriculum plan of the University of Zulia (LUZ ) and the draft Core technical laboratory, so that the student be prepared as an individual, able to cope in a knowledge society framed on the phenomenon of globalization, towards a comprehensive training set to develop specific skills as required by the new resolution by the Ministry of Higher Education of Venezuela, so that the graduate is related directly with the productive sector.