Perovskite quantum dots (QDs) confined within solid matrices via calcination methods exhibit superior environmental stability compared to colloidal perovskite QDs. However, matrix‐confined perovskite QDs generally display lower photoluminescence quantum yield (PLQY) than their colloidal counterparts, especially in the case of blue‐emitting mixed‐halide CsPb(Cl/Br) 3 QDs. Here, we identify residual tensile stress, originating from the mismatch in thermal expansion coefficients between the perovskite and the matrix, as a key factor responsible for the suppressed luminous efficiency in silica‐confined CsPb(Cl/Br) 3 QDs. Furthermore, we demonstrate that a simple hydrothermal treatment enables stress release in these silica‐confined QDs, leading to a significant enhancement in their PLQY. The resulting stress‐free silica‐confined CsPb(Cl/Br) 3 QDs exhibit record‐high PLQYs among reported blue‐emitting perovskite QDs synthesized via calcination methods, even approaching the PLQY of colloidal QDs. In addition, we find that stress release effectively suppresses both photoinduced halide segregation and thermal‐induced emission quenching in these silica‐confined CsPb(Cl/Br) 3 QDs. This work provides a new perspective for achieving blue‐emitting perovskite QDs with high PLQY and stability. image

Inverse design of three-dimensional porous media is central to applications in filtration, catalysis, energy storage, fuel cells, thermal management, and biomedical scaffolds, but remains challenging because many distinct pore geometries can share similar porosity or permeability while small structural changes can strongly affect transport behaviour. This paper proposes a physics-guided generative AI framework for property-targeted porous media design, combining a property-aware variational autoencoder, a conditional latent diffusion model, and an independently trained differentiable structure-to-property surrogate. The framework learns a compact, physically informative latent design space, generates porous structures conditioned on target porosity and directional permeability, and refines generated samples using property-level feedback during denoising and decoding. Experiments on procedurally generated structures and real micro-CT porous-media datasets show improved target-property matching, directional permeability control, and property correlation compared with representative property-aware variational-autoencoder and latent-diffusion baselines. The results demonstrate a scalable route towards controllable inverse design of complex porous geometries and establish a foundation for simulation-informed generative AI tools in engineering and advanced materials discovery.

Modeling the unsaturated soil hydraulic conductivity function (SHCF) is essential for understanding water movement in unsaturated zones and supporting effective agricultural and environmental management. Accurate estimation of SHCF parameters, particularly the α and n parameters of the van Genuchten–Mualem (VGM) model, remains a challenging endeavor due to the complex interplay of soil physical properties. Tree-based machine learning methods have shown promising capabilities in this area. To further assess and compare the performance of tree-based approaches, this study aimed to evaluate the efficiency of three algorithms, Cubist, RF, and light gradient boosting machine (LightGBM), in the parametric estimation of SHCF using 196 soil samples from the UNSODA database. Input variables, including sand, clay, soil bulk density (BD), field capacity (FC), and permanent wilting point (PWP), were structured into four progressively complex pedotransfer functions (PTFs). Results indicate that Cubist demonstrated the best overall generalization during testing, achieving the lowest average RMSD (7.165) across the four PTFs compared to RF (7.602) and LightGBM (8.068), although RF and LightGBM achieved marginally better performance on individual PTF-metric combinations. All three algorithms achieved high coefficients of determination (R2 ≥ 0.95) across all PTFs. Specifically, in PTF4, the best-performing model, Cubist achieved a 6.8% lower RMSD than RF and a 12.4% improvement over LightGBM. Shapley additive explanations (SHAP) conducted via XGBoost surrogate models, suggested that FC and PWP were the most influential predictors of SHCF among the variables examined. These findings suggest that Cubist is a viable approach for estimating SHCF, particularly when input data are limited to basic soil properties.

Gas production from unconsolidated formations is often challenged by sand production and low reservoir permeability. All past 11 field trials of gas production from hydrate reservoirs encountered various degrees of sand production, with five of them suspended due to severe sand production. This study investigates the potential of synthesizing open-cell polyurethane (PU) as a sand control filter and hydraulic fracturing proppant in water-saturated clayey sediments. The results show that the properties of formed polyurethane are heavily affected by constituent proportions, additives (e.g., catalyst and surfactant), the mixing sequence, and the hardening time. Simultaneous injection of catalyst and a premix (of toluene diisocyanate TDI, 1,4-butanediol BDO, and surfactant) into water can form polyurethane with consistent final volumes and correspondingly stable engineering properties. The stiffness and strength of polyurethane increase rapidly during the first 48 h of hardening and then stabilize at an unconfined compressive strength of UCS = similar to 1 MPa. The morphology of formed polyurethane, which is in localized chunks around the injection port as sand filters or in planar fractures propagating over a greater distance as proppants, can be manipulated by the injection flux, the amount of catalyst, and in situ effective stresses. This technique of using in situ synthesis of open-cell polyurethane, forming fracture proppants reaching the far field, followed by chunk-like filters around the injection ports, provides a novel solution for sustainable and efficient hydrocarbon recovery from unconsolidated sediments.

Gas invasion into fluid-saturated marine sediments is relevant to various geophysical and environmental processes, such as the formation of gas hydrate reservoirs and their behavior during depressurization-based gas production. The link between pore-scale mechanisms and macroscopic invasion patterns as well as their governing parameters, especially under high stress and intense flux conditions, remains unclear. We study gas invasion into water-saturated marine sediments using a coupled framework of the discrete element method and pore network modeling. We show that two dimensionless numbers, the stress number Σ and the seepage number D, govern five representative gas invasion patterns of capillary fracturing, capillary invasion, viscous fingering, seepage fracturing, and the transitional morphologies among them. The capillary number C, the stress number Σ, and the seepage number D collectively determine the shear, tensile, or cavity dominated fracturing in marine sediments. The results provide a description of gas migration regime transitions in marine sediments, which can help establish a scientific foundation to explain the development of marine cold seeps in nature and to design gas hydrate exploitation strategies.

Uncontrolled deep bleeding, commonly encountered in surgical procedures, combat injuries, and trauma, poses a significant threat to patient survival and recovery. The development of effective hemostatic agents capable of precisely targeting trauma sites in deep tissues and rapidly halt bleeding remains a considerable challenge. Drawing inspiration from the natural hemostatic cascade, we present platelet-like microspheres composed of silk fibroin (SF) and thrombus-targeting peptides, engineered to mimic natural platelets for rapid hemostasis in vivo. These peptide/SF hemostatic microspheres, formulated using a freezing self-assembly technology, closely resemble natural platelets in terms of size, shape, and zeta potential. Moreover, they exhibit favorable cytocompatibility, hemocompatibility, and anti-cell adhesion. Assessment of fibrin polymerization revealed that these hemostatic microspheres possessed enzymatic physiological functions, similar to activated platelets, facilitating platelet adhesion, fibrin binding, and wound-triggered hemostasis. Notably, these hemostatic microspheres rapidly target the bleeding site in vivo within 5 min, with minimal dispersion elsewhere, persisting after blood clot formation. Furthermore, these microspheres exhibit favorable metabolic kinetics, with 71% degradation occurring within one-day post-subcutaneous injection. Histological assessment revealed well-preserved organ structures and minimal inflammatory responses at 14 d post-injection, supporting their long-term biocompatibility. Importantly, they can be injected and targeted into damaged blood vessels, selectively binding to fibrin and forming blood clots within 2 min, resulting in a 74% reduction in bleeding volume compared to SF microspheres alone. Therefore, these injectable SF-based hemostatic microspheres emerge as promising candidates for future rapid hemostasis in tissue injuries.

Granular materials transition between unjammed (deformable) and jammed (rigid) states when adjusting their packing density. Here, we report on experiments demonstrating that the same kind of phase transition can be alternatively achieved through temperature-controlled particle shape change. Using a confined system of randomly-packed rod-like particles made of shape memory alloy (SMA), we exploit that shape recovery of these bent rods with rising temperature at a constant packing density leads to a jammed state. The responsible physical processes are elucidated with numerical simulations based on the Discrete Element Method. As an exemplary application of the uncovered mechanism, we engineer a smart clamp that can actively grip or release an object through the thermo-induced jamming or unjamming of the granular material, and robustly so under cyclic temperature changes. In the jammed state, its load-bearing capability surpasses the total SMA weight by a tunable margin, up to over 800-fold. The clamping design paves the way towards a new kind of functional devices based on the thermo-responsive jamming of shape memory granular materials.

Accurately reconstructing the intricate structure of natural organisms is the long-standing goal of 3-dimensional (3D) bioprinting. Projection-based 3D printing boasts the highest resolution-to-manufacturing time ratio among all 3D-printing technologies, rendering it a highly promising technique in this field. However, achieving standardized, high-fidelity, and high-resolution printing of composite structures using bioinks with diverse mechanical properties remains a marked challenge. The root of this challenge lies in the long-standing neglect of multi-material printability research. Multi-material printing is far from a simple physical assembly of different materials; rather, effective control of material interfaces is a crucial factor that governs print quality. The current research gap in this area substantively hinders the widespread application and rapid development of multi-material projection-based 3D bioprinting. To bridge this critical gap, we developed a multi-material projection-based 3D bioprinter capable of simultaneous printing with 6 materials. Building upon this, we established a fundamental framework for multi-material printability research, encompassing its core logic and essential process specifications. Furthermore, we clarified several critical issues, including the cross-linking behavior of multicomponent bioinks, mechanical mismatch and interface strength in soft-hard composite structures, the penetration behavior of viscous bioinks within hydrogel polymer networks, liquid entrapment and adsorption phenomena in porous heterogeneous structures, and error source analysis along with resolution evaluation in multi-material printing. This study offers a solid theoretical foundation and guidance for the quantitative assessment of multi-material projection-based 3D bioprinting, holding promise to advance the field toward higher precision and the reconstruction of more intricate biological structures.

We experimentally and computationally analyze impact-shock-induced stress wave propagation in packings of disordered flexible fibers. We find that dispersive wave propagation, associated with large stress attenuation, occurs much more prevalently in systems with larger fiber aspect ratios and moderate fiber flexibility. We trace these features to the microstructural properties of fiber contact chains and the energy-trapping abilities of deformable fibers. These findings provide insights into physics of the shock-impacted flexible fiber packings and open the way toward an improved granular-material-based damping technology.

Accurately reconstructing the intricate structure of natural organisms is the long-standing goal of 3-dimensional (3D) bioprinting. Projection-based 3D printing boasts the highest resolution-to-manufacturing time ratio among all 3D-printing technologies, rendering it a highly promising technique in this field. However, achieving standardized, high-fidelity, and high-resolution printing of composite structures using bioinks with diverse mechanical properties remains a marked challenge. The root of this challenge lies in the long-standing neglect of multi-material printability research. Multi-material printing is far from a simple physical assembly of different materials; rather, effective control of material interfaces is a crucial factor that governs print quality. The current research gap in this area substantively hinders the widespread application and rapid development of multi-material projection-based 3D bioprinting. To bridge this critical gap, we developed a multi-material projection-based 3D bioprinter capable of simultaneous printing with 6 materials. Building upon this, we established a fundamental framework for multi-material printability research, encompassing its core logic and essential process specifications. Furthermore, we clarified several critical issues, including the cross-linking behavior of multicomponent bioinks, mechanical mismatch and interface strength in soft-hard composite structures, the penetration behavior of viscous bioinks within hydrogel polymer networks, liquid entrapment and adsorption phenomena in porous heterogeneous structures, and error source analysis along with resolution evaluation in multi-material printing. This study offers a solid theoretical foundation and guidance for the quantitative assessment of multi-material projection-based 3D bioprinting, holding promise to advance the field toward higher precision and the reconstruction of more intricate biological structures.

Marine hydrate-bearing sediments (HBS) in the Nankai Trough and the South China Sea, characterized by high fines content and high hydrate saturation, are typically associated with very low porosity and permeability, which greatly undermines the hydrate exploitation efficiency. Inspired by the exploitation techniques of coals and shale gases, hydraulic fracturing could potentially be an effective way to improve the overall permeability of HBS and accordingly its gas production efficiency. This paper introduces a novel experimental study on the enhancement of gas production from HBS via combined hydraulic fracturing and depressurization method. The main properties examined are the viscosity of fracturing fluid and the perforated length of production well. Substantial improvement in gas production by hydraulic fracturing was observed, in terms of both the peak and long-term production rates. The most remarkable increase in peak production rate can be up to 90.4% and only half the time was required to achieve a total gas production of 70%. The optimal fluid viscosity of 500 mPa & sdot;s was identified in the present experiments. Fracturing fluids with lower viscosities would lead to only small fractures and limited increase in the overall permeability, while that with higher viscosities somewhat inhibit gas flow along fractures, both against the achievement of high gas production efficiency. In particular, sediment subsidence and sand production would be exacerbated at the presence of hydraulic fractures. Furthermore, a greater well perforated length was conductive to fracturing fluid discharge and thus facilitating gas production efficiency, in terms of not only shortening the fluid flow path but also alleviating the sand production. This study on hydraulic fracturing for HBS offers novel insights into enhancing the gas production efficiency and revealing potential engineering risks in practical applications.

Natural gas hydrate has vast reserves worldwide and is widely regarded as an efficient alternative energy resource. Gas seepage and the evolution of seepage channels during gas production from hydrate-bearing sediments are essential for the safe and economical exploitation of natural hydrate reservoirs. This study aims to investigate the formation mechanism of gas-driven fractures in hydrate-bearing sediments during hydrate dissociation and, for the first time, their resulting influences on gas production behavior and reservoir deformation. Samples with various porosities were depressurized at different rates by using a customized chamber equipped with multiple pressure and temperature sensors and see-through windows. The results show that gas produced from hydrate dissociation can lead to cavity formation and gas-driven fractures, which facilitate rapid gas migration and production. The gas production rate increased exponentially with sediment porosity and, likewise, the postproduction subsidence. In addition, an optimal porosity with improved gas production efficiency and mild reservoir subsidence was identified. These findings provide a theoretical basis for the deployment of production wells, gas production evaluation, and assurance of reservoir safety during the commercial exploitation of marine hydrate deposits.

Geomechanical and heat transfer characteristics of gas hydrate-bearing sediment (GHBS) are significantly affected by hydrate dissociation during gas production from reservoirs, which is typically tens of meters in thickness. This paper presents the development of an innovative in-flight apparatus that is capable of modeling hydrate dissociation in GHBS on a geotechnical centrifuge, by which a series of model tests are conducted under normal gravity (1g) and hypergravity (100g and 80g). The effects of the hypergravity field on the development of pore pressure, soil deformation, as well as particle migration and gas production during hydrate dissociation are explored. Results show that gas released from hydrate dissociation increases excess pore pressure and changes the soil pore structure. During hydrate dissociation, the accumulation of excess pore pressure leads to the development of gas-driven fractures and the subsequent formation of a dominant seepage channel. The critical excess pore pressure of fracture formation in the 100g test is higher than that in the 1g test. The dominant seepage channel promoting fluid seepage and fine particle migration is more likely to be formed into obvious fracture structures under 100g compared with slender pipe structures under 1g. Two peaks are witnessed in gas production in the 100g test, corresponding to the stage at maximum pressure difference and at the complete formation of dominant seepage channels, which is consistent with that in the field trails. These results indicate that the formation of fracture during hydrate dissociation is beneficial to efficient gas production, while the problem of particle migration should be carefully paid attention to.

OBJECTIVES:Exploring the anisotropic mechanical behavior of cancellous bone is crucial for in-vivo bone biomechanical analysis. However, it is challenging to characterize anisotropic mechanical behaviors under low-resolution (LR) clinical CT images due to a lack of microstructural information. The data-driven method proposed in this article accurately characterizes the anisotropic mechanical properties of cancellous bone from LR clinical CT images. METHODS:The trabecular bone cubes of sheep are used to obtain a high-resolution (HR) micro-CT and an LR clinical CT image dataset. First, an auto-encoder model is trained using HR image data. Microstructural features are extracted by the encoder. A fast super-resolution (FSR) model is trained to map LR bone cubes to the features extracted from corresponding HR samples. The pretrained FSR model is used to convert LR clinical CT images to encoded microstructural features. The features are later used to predict target histomorphological parameters, anisotropic elastic tensors, and fabric tensors based on a fully connected neural network. RESULTS:The data-driven model accurately predicts the elastic tensor and fabric tensor of trabecular bones with LR CT images with 0.6 mm/pixel spatial resolution. It was verified that LR clinical CT images could generate microstructural information using a generative deep-learning model and an up-sampling operation. SIGNIFICANCE:This study proves that clinical medical images of cancellous bone can be used for analysis of complex mechanical properties using a data-driven method, which is useful for real-time bone defect diagnosis and personalized bone prosthesis design in clinical application.

Highly luminescent CsPbBr 3 -DPSI/MS composites with excellent overall stabilities are synthesized using a solid-state reaction method. These composites exhibit a promising foreground in high-performance LCD and X-ray imaging.

Puncture of soft solids involves the process of piercing through a soft solid material using a sharp object, which is of great interest in biomedical and industrial applications. In this work, we investigate the puncture of soft solids by a commercial medical needle using polyacrylamide (PAAm) hydrogel as the model material. We measure the relationship between the depth of puncture and force exerted on the needle as it penetrates and retracts from the PAAm hydrogel at different speeds, and interpret the results of the experiments. We find that the puncture force fluctuates with the increasing puncture depth during needle penetration, while the retraction force decreases almost linearly with the retraction depth. Both the puncture and retraction forces, as well as the amplitude and period of the puncture force fluctuation, are positively related to the loading speed. We estimate the size of the crack, which is difficult to directly recognize from experiments, induced by puncture using the critical puncture depth at which the needle first pierces the hydrogel. We find that the size increases with the puncture speed. Moreover, we obtain a work balance relationship between the energy done by the puncture force minus friction (Fp-Fr) and the sum of the energy required for crack propagation and the elastic energy stored in the hydrogel bulk. These findings from our research contribute to a comprehensive understanding of deep indentation and puncture in soft materials. These results carry important implications for the design of biomedical and industrial devices, where the puncturing of soft solids is a critical procedure.

Natural gas hydrate in deep sea exists in a certain temperature and pressure condition. The depressurization rate during hydrate dissociation by depressurization has a great impact on the gas production rate and hydrate-bearing sediment deformation characteristics. In order to investigate the influence of depressurization rate on temperature field, pore pressure field, deformation characteristics, and gas production rate of hydrate-bearing sediment, a group of depressurization tests with different depressurization rates was carried out on the apparatus independently developed by Zhejiang University that can perform linear gradient servo depressurization for simulating the hydrate decomposition process. The results show that the temperature decreases first from the perimeter of the shaft where the decomposition region starts, and then gradually spreads to the surrounding sediment at the initial stage of depressurization. Increasing the depressurization rate appropriately can improve the production efficiency of the reservoir, but the higher depressurization rate may cause the hydrate regeneration, which is not conducive to gas production. Optimal gas production efficiency can be obtained by selecting a specific depressurization rate. In the process of hydrate exploitation, the pore shape of the hydrate-bearing sediment can be divided into three types, according to the connection degree between pores and the surrounding area: completely sealed, partially sealed, and open. After hydrate exploitation, the shallow surface soil of reservoir can be divided into three areas based on the deformation characteristics: Zone I is the soil layer around the shaft, showing a funnel-shaped subsidence structure; the soil layer in Zone II is flat with no obvious disturbance; Zone III is the boundary soil layer, where the upward migration of water and gas production is blocked, leading to a mound like uplift zone. These deformation characteristics are related to the migration paths and modes of gas production in hydrate-bearing sediment. Through similarity analysis, the corresponding relationships between the decomposition time and gas production of the model and prototype are given.

As photocrosslinkable materials, methacryloyl-modified hydrogels are widely used as bioinks in tissue engineering. Existing printing methods to use these hydrogels, including changing the viscosity of the material or mixing them with other printing components, have been explored, but their application has been limited due to low printing quality or high cost. In addition, the complex operation of bulky equipment restricts the application of these existing printing methods. This study presents a lightweight stereolithography-based three-dimensional (3D) bioprinting system with a smart mechanical and structural design. The developed bioprinter dimensions were 300 mm × 300 mm × 200 mm and it can be placed on a benchtop. The equipment has a mini bioink chamber to store a small amount of bioink for each printing. We systematically investigated the point-by-point curing process in the 3D bioprinting method, which can print mixed cells accurately and have good biocompatibility. Here, we provide a compact, low-cost stereolithography bioprinting system with excellent biocompatibility for 3D bioprinting with methacryloyl-modified hydrogels. It can be potentially used for drug screening, studying pathological mechanisms, and constructing biological disease models.

In this paper, the time-resolved particle image velocimetry (TR-PIV) and match index refractive (MIR) techniques were used to study the flow field in a large range (0 - 22 D-h) downstream a spacer grid (SG) in a 5 x 5 rod bundle channel at different Reynolds number. The sodium chloride solution (1%) is used as the working fluid to reduce the refractive index error of fluorinated ethylene propylene (FEP) and water. The proper orthogonal decomposition (POD) background removal technique was used to minimize the FEP reflection. These methods greatly reduced the interference of background noise and improved the accuracy of cross-correlation calculation. For TR-PIV velocity fields downstream of the mixing vanes, time-averaged, statistical, spectral, and cross-correlation analysis were performed for the instantaneous full-field experimental data. The transport characteristics of coherent structures in different subchannels of rod bundles are calculated and discussed. The results show that the SG caused a relatively large transverse velocity and reduces the axial velocity. With the increase of the Reynolds number, the SG promotes the generation of transverse flow and has a great resistance to the axial flow. There is relatively large turbulence intensity downstream of the SG due to the mixing effect. The attenuation of transverse turbulence intensity component is slower than the axial component. Moreover, spectrum analysis shows that cross-arranged mixing vanes will generate periodic vortices but single mixing vane will not. These periodic vortices gradually propagate downstream along the inner subchannel and dissipate in the gap subchannel due to the effect of viscosity. The cross-correlation analysis shows that the mixing effect of the SG will reduce the scale of the coherent structure, and increase the convection velocity. The results of current research are helpful for understanding the strong anisotropic turbulence in the rod bundle channel with SG. Finally, the experimental results can be utilized to benchmark the applicability of turbulence models under different Reynolds number and the performance of partially averaged Naiver-Stokes or multiple RANS algorithms downstream of the SG.

As a fundamental issue, cell-scaffold interaction has drawn increased attention in tissue engineering. The ability of tendril-climbers to perceive position and climb up toward the trellis in an ingenious manner induces interest. Thus, the question arises whether the cell can also grow as ingenious as the plant. Prompted by the climbing mechanism of tendril climbers, we proposed a novel method for inducing cell growth by using specially designed scaffolds with heterogeneous structures. A high-resolution 3D printing method via melt direct writing for fabricating these scaffolds was developed. By melting biodegradable polymers in the nozzle and high-voltage attraction, scaffolds with fiber diameters measuring 3μm can be printed layer by layer. Heterogeneous structures, such as various fiber diameters and pore sizes, can be freely printed in one scaffold at the different locations by adjusting correlated parameters. Owing to these properties of the scaffold, interesting phenomena of cell growth were observed. Human umbilical vein endothelial cells (HUVECs) exhibited different growth rates on the scaffold with different pore sizes. And bone marrow stem cell (BMSCs) showed several morphological characteristics on the scaffold consisting of fibers with specific diameters. Therefore, we can regulate and control cell growth to different status in one scaffold by merely designing structures. This study generally provides a structure-induced cell growth strategy for better simulating in-vivo like environment.