Yimin Luo

Supplementary video S2.mp4

Cellular organization and mechanotransduction pathways are crucial regulators of tissue morphogenesis, whereas their dysregulation contributes to pathologies. Overactive myofibroblasts are key drivers of fibrosis, yet how their presence alters collective cellular ordering remains unclear. Owing to steric interactions, elongated cells exhibit local order. Topological defects, where alignment is disrupted, have been postulated to serve as mechanical centres. In this study, we examine how incorporating slower-moving myofibroblast phenotype impacts defect relaxation in monolayers consisting of co-cultured fibroblasts and myofibroblasts. In this system, myofibroblasts act as the less active component. Increasing their fraction increases disorder strength and slows defect recombination. On microgrooved surfaces, higher myofibroblast concentrations lead to worse alignment, suggesting single-cell mechanosensing and cell–cell interactions act jointly. Furthermore, we found that myofibroblasts preferentially localize at negatively charged $-\frac{1}{2}$ defects, whereas fibroblasts localize at $+\frac{1}{2}$ defects. Consequently, the slowdown of recombination dynamics can be partially attributed to myofibroblasts' preferential association with the less mobile $-\frac{1}{2}$ defects, increasing local friction and impeding defect mobility. This localization may also reduce compressive stress on myofibroblasts, as indicated by immunofluorescence of a downstream mechanotransducer. This work provides insights into possible connections between topological defects and cell motility in mixed phenotype monolayers.

Supplementary video S2.mp4

Cellular organization and mechanotransduction pathways are crucial regulators of tissue morphogenesis, whereas their dysregulation contributes to pathologies. Overactive myofibroblasts are key drivers of fibrosis, yet how their presence alters collective cellular ordering remains unclear. Owing to steric interactions, elongated cells exhibit local order. Topological defects, where alignment is disrupted, have been postulated to serve as mechanical centres. In this study, we examine how incorporating slower-moving myofibroblast phenotype impacts defect relaxation in monolayers consisting of co-cultured fibroblasts and myofibroblasts. In this system, myofibroblasts act as the less active component. Increasing their fraction increases disorder strength and slows defect recombination. On microgrooved surfaces, higher myofibroblast concentrations lead to worse alignment, suggesting single-cell mechanosensing and cell–cell interactions act jointly. Furthermore, we found that myofibroblasts preferentially localize at negatively charged $-\frac{1}{2}$ defects, whereas fibroblasts localize at $+\frac{1}{2}$ defects. Consequently, the slowdown of recombination dynamics can be partially attributed to myofibroblasts' preferential association with the less mobile $-\frac{1}{2}$ defects, increasing local friction and impeding defect mobility. This localization may also reduce compressive stress on myofibroblasts, as indicated by immunofluorescence of a downstream mechanotransducer. This work provides insights into possible connections between topological defects and cell motility in mixed phenotype monolayers.

SI.pdf

Supplementary video S1.mp4

Supplementary video S1.mp4

SI.pdf

Highly regulated cellular anisotropy is widely observed in vivo. Yet, reproducing tissue anisotropy in vitro is an open challenge. While considerable literature exists on engineering cell alignment, inferring or mimicking cell reorientation, proliferation, and force generation in a tightly coupled process presents unique challenges from fabrication to characterization and modeling. Advances in miniaturization, synthetic fibrous materials, and bioprinting have enabled oriented cell assembly and force generation, making engineered macroscopic shape transformation a reality. Alternatively, bottom-up strategies build complexity from simple, self-organizing components. Steric interactions among cells confer liquid crystal (LC)-like properties, suggesting that tools from LC processing can be leveraged to engineer cell alignment. These tools are also broadly accessible, as they do not require specialized synthesis or instrumentation typically unavailable in standard biological laboratories. Meanwhile, theoretical frameworks for nematic alignment and topological defects are well established. The active nematic model has proven increasingly effective in explaining collective cell behaviors, and an expanding array of active nematic structures is being identified in biological systems. In this Review, we will outline recent progress on tapping into the active nematic nature of cells to organize supracellular, millimeter-scale structures in both 2D and 3D. We will introduce advances in recreating complex cellular order through substrate guidance and in vitro scaffolding. The experimental progress stimulates bottom-up modeling of collective behaviors, activity-enriched description of nematic alignment and topological defects, and machine learning approaches for predictions and uncertainty quantification. These efforts are increasingly complemented by developments in high-throughput imaging for materials characterization, statistical learning approaches for model construction, and generative models for data inversion. Together, a combination of experimental, computational, and data-driven approaches paves the way for the ultimate realization of in vitro, tissue-like morphogenesis.

With the advancement of deep-sea exploration and marine energy extraction, lightweight alloy equipment such as unmanned underwater vehicles and deep-submergence vehicles must be capable of withstanding increasingly severe alternating hydrostatic pressure (AHP) during descent and recovery. However, rigid microarc oxidation coatings are prone to interfacial failure due to their excessive elastic modulus. Herein, a porous organic–organic coating was fabricated, exhibiting a thickness of approximately 35 μm, a porosity of 21%, and a water contact angle of 135°. After 120 cycles of AHP (0–40 MPa), the coating initially underwent densification (thickness decreased by 10.4% and porosity by 16.29%) to enhance the yield strength of the flexible skeleton, then entered a stable service plateau where variations in thickness and porosity remained below 3%. Thus, an interfacial mechanical evolution model for porous organic–organic coatings was established. By integrating the effective stress principle, a “skeleton strengthening” design criterion was proposed based on operating pressure ( P ), skeleton yield limit (σ y ), and initial porosity (η). This criterion was validated by the phase interface failure observed in porous inorganic–organic coatings under AHP, providing guidance for the engineering design of pressure-resistant materials.

). Additionally, one month of ambient on-road tests confirm that the coated windshields maintain remarkable antifouling performance against recalcitrant stains (coverage area < 2%). This work provides a novel topological design rule for developing multifunctional protective interfaces in fields including transport, new energy, and buildings.

Fibrosis is driven in part by the transition of healthy fibroblasts to a contractile phenotype called myofibroblasts. The mechanics of the extracellular matrix play a crucial role in regulating cell fates and behaviors during this transition. However, most studies to date focus on cells grown on 2D surfaces and matrices with homogeneous properties. This leaves open how local rigidity differentially regulates the behaviors of both phenotypes in 3D environments, including polarization, contraction, and maintenance of phenotypes, during remodeling. Here, we engineer 3D microgel-in-collagen composites by embedding low-volume fractions of cell-scale microgels with two levels of rigidity, mimicking healthy and pathological tissues that are stiffer than the surrounding collagen but do not significantly change the bulk modulus. We find that microgels serve as mechanical centers: both phenotypes polarize toward microgel inclusions. The polarization response decays as a power-law with distance ∼ r – n, decreasing more slowly for myofibroblasts ( n ≈ 0.35) than fibroblasts ( n ≈ 0.81), indicating that myofibroblasts are more sensitive to small mechanical variations. In situ measurements finds that forces are highest for myofibroblasts near stiff microgels and lowest for fibroblasts near soft microgels. Local rigidity also stabilizes the myofibroblast phenotype: Both the ordering of the proinflammatory marker α-smooth muscle actin and nuclear Yes-associated protein localization persist for cells cultured with stiff microgels over several days but diminish quickly for those cultured with soft microgels and in pure collagen. Together, these results reveal a rigidity- and phenotype-dependent feedback loop: stiff inclusions induce cell polarization and collagen remodeling via a contractile force, which in turn maintain the myofibroblast phenotype. Our study positions mechanical heterogeneity as a useful and sensitive handle to probe and potentially modulate early fibrotic progressions.

To solve oil starvation and lubrication failure in low-speed and heavy-load machinery rotation or sliding parts, the application of solid-liquid dual lubricating coatings is very extensive. The design and preparation of porous structures are key concerns, potentially impacting the friction coefficient and temperature rise at the friction interface. In this work, a robust micronano porous polytetrafluoroethylene/polyphenylene sulfide (PTFE/PPS) coating with a thickness of 20-40 μm was readily prepared by freezing the wet film at -10 °C, inspired by frozen tofu. The porosity and average pore diameter of the coating were analyzed to be about 7.4% and 50 μm, respectively. The pore formation mechanism is proposed by modulating the microphase separation of PTFE and PPS components through the synergistic effect of ice crystals as a pore-forming agent and a surfactant as a pore-expanding agent. The oil friction coefficient (μ' ≈ 0.054) was reduced by 65% than that of the dry friction condition (μ ≈ 0.155), and the wear resistance life was greater than 2.57 km/μm. The porous surface and its lipophilicity facilitate the oil to be replenished at the friction interface. This is expected to provide the idea for designing porous polymer coatings to apply in solid-liquid dual lubrication.

Solid propellant slurry is a high solid content suspension, and its rheological properties are very complex. In order to solve the problem that it is hard to estimate the process propertie of 3,3-bis(azidomethyl) oxetane-tetrahydrofuran copolyether (PBT) solid propellant slurry, the concept of liquid film thickness in propellant was proposed by analyzing the mesoscopic structure of PBT solid propellant slurry, and the calculation method of liquid film thickness under different propellant packing grade ratios is given. Four kinds of filler particle size are used as examples, the theory of tight packing of tertiary particles was extended to multi-gradation. Furthermore, based on the theory of packing, the relationship between the liquid film thickness of the propellant and the particle size of the filler is obtained, that is, the liquid film thickness becomes thinner with the decrease of the particle radius and changes proportionally with the particle radius. In this work, the analysis method provides theoretical guidance for propellant formulation design, thereby reducing the number of experiments, shortening the propellant formulation development cycle, and reducing labor and material costs.

During morphogenesis, cells collectively execute directional forces that drive the programmed folding and growth of the layers, forming tissues and organs. The ability to recapitulate aspects of these processes in vitro will constitute a significant leap forward in the field of tissue engineering. Free-standing, self-organizing, cell-laden matrices are fabricated using a sequential deposition approach that uses liquid crystal-templated hydrogel fibers to direct cell arrangements. The orientation of hydrogel fibers is controlled using flow or boundary cues, while their microstructures are controlled by depletion interaction and probed by scattering and microscopy. These fibers effectively direct cells embedded in a collagen matrix, creating multilayer structures through contact guidance and by leveraging steric interactions amongst the cells. In uniformly aligned cell matrices, oriented cells exert traction forces that can induce preferential contraction of the matrix. Simultaneously, the matrix densifies and develops anisotropy through cell remodeling. Such an approach can be extended to create cell arrangements with arbitrary in-plane patterns, allowing for coordinated cell forces and pre-programmed, macroscopic shape changes. This work reveals a fundamentally new path for controlled force generation, emphasizing the role of a carefully designed initial orientational field for manipulating shape transformations of reconstituted matrices.

jointly contribute to energy storage and dissipation across the interface. Additionally, droplet impact experiments validated that the greater the interfacial wettability difference, the stronger the energy storage or dissipation effect. This study establishes the "Smart" valve as an efficient and precise fluid control solution that requires no external power, applicable in fields such as chemical engineering, biomedicine, and microfluidics.

Polymeric hydrogels, known for their excellent mechanical properties and pre-cross-linking flowability, provide a promising solution for recycling waste propellants, ensuring safety and maintaining explosive performance. This study developed a double cross-linked network energetic hydrogel that effectively combines mechanical strength with explosive capabilities. Using a Ford 4 Cup, temperature data logger, universal testing machine, and detonation performance tests, we examined the impacts of kinematic viscosity, cross-linking time, compressive strength, and explosive properties. The optimal kinematic viscosity for stabilizing hollow glass microspheres (GM) was found to be 129.7 mm 2 /s. Cross-linking time was negatively correlated with initiator, catalyst levels, and reaction temperature, but positively correlated with retarder content. Compressive strength increased with acrylamide (AM) content and showed an initial rise before decreasing with N,N′-methylenebisacrylamide (MBAA) content and reaction temperature. The maximum compressive strength was achieved with 5% MBAA (of AM mass fraction) at 40 °C. Detonation velocity and steel plate damage decreased with increasing AM content and initially increased then decreased with GM content. A balance of mechanical and explosive properties was achieved with 6% AM and 4% GM, resulting in a detonation velocity of 4536 m/s. This hydrogel shows significant potential for waste munitions management.

Abstract During morphogenesis, cells collectively execute directional forces that drive programmed folding and growth of the layers, forming tissues and organs. The ability to recapitulate aspects of these processes in vitro would constitute a significant leap forward in the field of tissue engineering. Free-standing, self-organizing, cell-laden matrices are fabricated using a sequential deposition approach that uses liquid crystal-templated hydrogel fibers to direct cell arrangements. The orientation of hydrogel fibers is controlled using flow or boundary cues, while their microstructures are controlled by depletion interaction and probed by scattering and microscopy. These fibers effectively direct cells embedded in a collagen matrix, creating multilayer structures through contact guidance and by leveraging steric interactions amongst the cells. In uniformly aligned cell matrices, oriented cells exert traction forces that can induce preferential contraction of the matrix. Simultaneously, the matrix densifies and develops anisotropy through cell remodeling. Such an approach can be extended to create cell arrangements with arbitrary in-plane patterns, allowing for coordinated cell forces and pre-programmed, macroscopic shape changes. This work reveals a fundamentally new path for controlled force generation, emphasizing the role of a carefully designed initial orientational field for manipulating shape transformations of reconstituted matrices.

This paper is focused on the electrochemical corrosion protection issue of marine equipment during actual service. The two metals (45 # steel and 6061 aluminum alloy) are brought into contact to form the galvanic corrosion. The micro/nano-structure with honeycomb-like protrusions (1.82 μm) and network-like texture (370–460 nm) is fabricated on the steel surface, which becomes superhydrophilic (water contact angle (WCA) ≈ 0°). Perfluorooctanoic acid, a low surface energy modifier, is used to modify the corroded micro/nano-texture surface. Thus, a hydrophobic organic coating (WCA = 158° ± 4°) is fabricated, which effectively inhibits droplet wetting and penetrating into the metal layer. Furthermore, it is found that the coating surface still maintained its hydrophobicity (WCA = 101.5°) after 2 h of the coating immersed in the corrosive solution. Thus, a new surface remanufacture method, utilizing the galvanic corrosive surface to prepare the hydrophobic coating, is proposed. This study hopes to provide new ideas for designing the protective coating applied to engineering maintenance.

Estimating parameters from data is a fundamental problem in physics, customarily done by minimizing a loss function between a model and observed statistics. In scattering-based analysis, it is common to work in the reciprocal space. Researchers often employ their domain expertise to select a specific range of wave vectors for analysis, a choice that can vary depending on the specific case. We introduce another paradigm that defines a probabilistic generative model from the beginning of data processing and propagates the uncertainty for parameter estimation, termed the ab initio uncertainty quantification (AIUQ). As an illustrative example, we demonstrate this approach with differential dynamic microscopy (DDM) that extracts dynamical information through minimizing a loss function for the squared differences of the Fourier-transformed intensities, at a selected range of wave vectors. We first show that the conventional way of estimation in DDM is equivalent to fitting a temporal variogram in the reciprocal space using a latent factor model as the generative model. Then we derive the maximum marginal likelihood estimator, which optimally weighs the information at all wave vectors, therefore eliminating the need to select the range of wave vectors. Furthermore, we substantially reduce the computational cost of computing the likelihood function without approximation, by utilizing the generalized Schur algorithm for Toeplitz covariances. Simulated studies of a wide range of dynamical systems validate that the AIUQ method improves estimation accuracy and enables model selection with automated analysis. The utility of AIUQ is also demonstrated by three distinct sets of experiments: first in an isotropic Newtonian fluid, pushing limits of optically dense systems compared to multiple particle tracking; next in a system undergoing a sol-gel transition, automating the determination of gelling points and critical exponent; and lastly, in discerning anisotropic diffusive behavior of colloids in a liquid crystal. These studies demonstrate that the new approach does not require manually selecting the wave vector range and enables automated analysis.

Nano aluminum powder effectively enhances reactivity, thereby improving energy-containing materials' performance. To investigate micro-nano self-assembled aluminum powders' energy output and their application in composite explosives, we tested the heat of combustion and ignition characteristics (ignition delay, ignition energy, flame propagation speed) using oxygen bomb calorimetry and Hartmann tube. Results showed that the combustion heat decreased with increasing nano aluminum powder content. The addition of nano aluminum powders substantially decreased ignition delay and energy, enhancing the combustion rate and reactivity of aluminum powder dust. The ranking of reactivity among the five aluminum powders was as follows: μ@n-Al-10 % > μ@n-Al-5% > μ/n-Al-10 % > μ/n-Al-5% > μAl. Assessing explosives containing various aluminum powders showed that the self-assembled 5 % content sample had the highest heat of detonation at 8490 kJ/kg. Mechanical sensitivity increased with higher nano aluminum powder content, with explosives containing 5 % nano content exhibiting the highest safety performance.

Anisotropic hydrogels have found widespread applications in biomedical engineering, particularly as scaffolds for tissue engineering. However, it remains a challenge to produce them using conventional fabrication methods, without specialized synthesis or equipment, such as 3D printing and unidirectional stretching. In this study, we explore the self-assembly behaviors of polyethylene glycol diacrylate (PEGDA), using disodium cromoglycate (DSCG), a lyotropic chromonic liquid crystal, as a removable template. The affinity between short-chain PEGDA (Mn = 250) and DSCG allows polymerization to take place at the DSCG surface, thereby forming anisotropic hydrogel networks with fibrin-like morphologies. This process requires considerable finesse as the phase behaviors of DSCG depend on a multitude of factors, including the weight percentage of PEGDA and DSCG, the chain length of PEGDA, and the concentration of ionic species. The key to modulating the microstructures of the all-PEG hydrogel networks is through precise control of the DSCG concentration, resulting in anisotropic mechanical properties. Using these anisotropic hydrogel networks, we demonstrate that human dermal fibroblasts are particularly sensitive to the alignment order. We find that cells exhibit a density-dependent activation pattern of a Yes-associated protein, a mechanotransducer, corroborating its role in enabling cells to translate external mechanical and morphological patterns to specific behaviors. The flexibility of modulating microstructure, along with PEG hydrogels' biocompatibility and biodegradability, underscores their potential use for tissue engineering to create functional structures with physiological morphologies.

The dynamic wetting behavior of droplets has been of wide concern due to the hazards of accretion/icing of supercooled droplets on engineering components/systems served in low temperature freezing rain environment; thus, it is urgent to establish the relationship between droplet depinning/removing behaviors and surface characteristics. In this article, the actual rotation conditions of moving components such as wind turbine blades are simulated. The self-cleaning hydrophobic coating surface(S1) and bionic superhydrophobic coating surface(S2) show outstanding droplet removal performance compared to hydrophilic bare steel surface(S0), and the average speed of the droplet removal is increased by 400–500%. The “creeping-sliding” behavior of droplets on self-cleaning coatings is investigated by the change of droplet displacement( ΔD ). The effect of the energy storage caused by the droplet creeping process provides initial kinetic energy for the droplet removal. Combined with the experimental data and theoretical model, the critical depinning resistance is calculated. The difference of the wetting interface free energy( ΔE x ) during the dynamic wetting process of the droplets on the bionic superhydrophobic self-cleaning surface is researched. And the influence mechanism of the droplet embedded depth( x ) on the creeping/sliding behavior in the nanotexture is clarified. Thus, the mechanical criterion of droplet depinning is proposed (the error is about 10%). The results can provide a theoretical basis for the design principle of antifreezing rain coatings on moving components.

Given the prevalence of Al/RDX energetic dust in industrial production, this study investigates their ignition safety and explosion hazards using Hartmann tubes and 20 L spherical explosion containers. The minimum ignition energy (MIE) increases from 20 mJ to 55 mJ as RDX content increases, indicating that adding RDX enlarges the effective particle size of the dust, thereby reducing its ignition sensitivity. A logistic regression model was used to develop a fitting equation for ignition probability, correlating dust concentration and ignition energy. The flame propagation velocity and explosion pressure of the energetic dust initially increase and then decrease with increasing RDX content. Optimal combustion characteristics were observed at 20% RDX, with the maximum flame propagation velocity of 101 m·s-1. However, the peak flame temperature decreases with increasing RDX content. The maximum explosion pressure and maximum explosion index at 1.77 MPa and 186.99 MPa·m·s-1 respectively, at 40% RDX content. These findings highlight that 20% RDX content yields the best combustion characteristics, while 40% RDX content offers the maximum explosive potential, providing valuable insights for enhancing safety measures in industrial applications involving energetic dusts.

In view of the technology bottleneck of the adhesion failure of traditional functional protective coatings on the smoother surface of precise parts served in the marine atmosphere, a room-temperature-curable fluoropolymer/polyurethane (denoted as RFP) polymer composite coating of 20-30 μm is prepared on the metal substrates. Static pull-off and dynamic friction test methods are used to evaluate the interface adhesion of the coating. The coating shows superior adhesive strength of 18-24 MPa on a variety of metal substrates with a wide range of surface roughness (Ra=0.1-1.6 μm). The friction coefficient of the coating surface is about 0.05-0.08, and the wear life is up to 9-12 km/μm. Furthermore, the adhesion strength of the coating remains 12-14 MPa after 1600 h of salt spray while the wear life of the coating keeps 3-9 km/μm after 720 h of salt spray. The influences of surface roughness , surface free energy (), surface potential of the metal substrates and the bonding force at substrate-coating interface on the adhesive energy are discussed, and the mechanism of "physical-chemical-surface" synergetic enhanced interface adhesion is proposed. The RFP coating is used as the intermediate layer for traditional PU and EP coatings to improve their adhesion on smooth aluminum substrate from 1.39 MPa to 17.5 MPa (increased by 1260%). Thus, the polymer coating has the potential to provide technical support for the development of long-term anticorrosive coating technology for precision components of marine high-tech equipment.

High-throughput microrheology and simple viscosity modeling can be used to continuously monitor the kinetic evolution of polymer molecular weight during controlled polymerizations.

Estimating parameters from data is a fundamental problem, customarily done by minimizing a loss function between a model and observed statistics. In scattering-based analysis, researchers often employ their domain expertise to select a specific range of wave vectors for analysis, a choice that can vary depending on the specific case. We introduce another paradigm that defines a probabilistic generative model from the beginning of data processing and propagates the uncertainty for parameter estimation, termed the ab initio uncertainty quantification (AIUQ). As an illustrative example, we demonstrate this approach with differential dynamic microscopy (DDM) that extracts dynamical information through Fourier analysis at a selected range of wave vectors. We first show that the conventional way of estimation in DDM is equivalent to fitting a temporal variogram in the reciprocal space using a latent factor model. Then we derive the maximum marginal likelihood estimator, which optimally weighs the information at all wave vectors, therefore eliminating the need to select the range of wave vectors. Furthermore, we substantially reduce the computational cost by utilizing the generalized Schur algorithm for Toeplitz covariances without approximation. Simulated studies validate that AIUQ improves estimation accuracy and enables model selection with automated analysis. The utility of AIUQ is also demonstrated by three distinct sets of experiments: first in an isotropic Newtonian fluid, pushing limits of optically dense systems compared to multiple particle tracking; next in a system undergoing a sol-gel transition, automating the determination of gelling points and critical exponent; and lastly, in discerning anisotropic diffusive behavior of colloids in a liquid crystal. These outcomes collectively underscore AIUQ's versatility to capture system dynamics in an efficient and automated manner.