Search Results (132)

The transition to a circular economy requires assessment tools that capture not only the environmental and economic performance of products but also their circular design, functionality, and durability. While Life Cycle Assessment (LCA) and Life Cycle Costing (LCC) are widely used, they alone do not capture modularity, reparability, reuse potential, or product lifespan. This study introduces a novel, integrated framework combining LCA, LCC, and product-level circularity indicators to provide a holistic evaluation of sustainability and circularity. In this study, two types of injection molds for plastic part production are compared: a conventionally manufactured mold and an additively manufactured metal mold produced by Laser Powder Bed Fusion (L-PBF) technology. The comparison integrates Life Cycle Assessment (LCA), Life Cycle Costing (LCC), and a set of micro-circularity indicators, including the Material Circularity Indicator (MCI), Recycling Desirability Index (RDI), circular design guidelines (CDG), Disassembly Effort Index (DEI), longevity indicator (LI), and Circular Economy Indicator Prototype (CEIP). Results show that the AM mold exhibits lower environmental impacts across almost all categories, while its slightly higher initial cost is largely offset by reduced indirect costs over the product lifecycle. Micro-circularity indicators reveal that the AM mold achieves higher material circularity and better circular design performance (MCI, CDG, CEIP) but shows only minor improvements in disassembly and recyclability (DEI, RDI) and lower longevity (LI) compared to the conventional mold, highlighting potential limitations for remanufacturing and end-of-life recovery. The novelty of this study lies in the integrated application of LCA, LCC, and multiple micro-circularity indicators, providing an operational framework for evaluating circular design, reparability, and durability in additive manufacturing and enabling informed, holistic decision-making for truly circular products. Full article

After implantation in vivo, airway stents are prone to negative biological effects, such as platelet adhesion, aggregation, and blood coagulation, which may lead to vascular occlusion and thrombosis. Therefore, when studying the antithrombotic properties of vascular grafts, it is crucial to construct a fiber film-coated airway stent with antithrombotic properties. In this paper, PTFE/TPU fiber film was prepared by emulsion electrospinning, and heparin aldehyde group was modified to covalently graft with the fiber film to obtain heparin-loaded fiber film (Hep-PT fiber film), and a heparin-loaded PTFE fiber film-coated airway stent (Hep-PT fiber film-coated airway stent) was prepared. Covalent grafting improves the stability of heparin and promotes the long-term stable release of heparin. The loading of heparin increases the fiber nodes between the fiber films, increases the friction between the fibers, and improves the mechanical properties and ability of the fiber film to resist external forces. At the same time, the Hep-PT fiber film-coated airway stent exhibits excellent cytocompatibility, making it an ideal candidate system for airway stent materials. Full article

The flexible micro-structured surface found in biological skins exhibits remarkable drag reduction properties, inspiring applications in the aerospace industry, underwater exploration, and pipeline transportation. To address the challenge of efficiently replicating such structures, this study presents a composite flexible polymer film with a bio-inspired micro-dimple array, fabricated via an integrated process of precision milling, polishing, and micro-injection molding using thermoplastic polyurethane (TPU). We systematically investigated the influence of key injection parameters on the shape accuracy and surface quality of the film. The experimental results show that polishing technology can significantly reduce mold core surface roughness, thereby enhancing film replication accuracy. Among the parameters, melt temperature and holding time exerted the most significant effects on shape precision PV and bottom roughness R_a, while injection speed showed the least influence. Under optimized conditions of a melt temperature of 180 °C, injection speed of 60 mm/s, holding pressure of 7 MPa, and holding time of 13 s, the film achieved a micro-structure shape accuracy of 13.502 μm and bottom roughness of 0.033 μm. Numerical simulation predicted a maximum drag reduction rate of 10.26%, attributable to vortex cushion effects within the dimples. This performance was experimentally validated in a flow velocity range of 0.6–2 m/s, with the discrepancy between simulated and measured drag reduction kept within 5%, demonstrating the efficacy of the proposed manufacturing route for flexible bio-inspired drag reduction film. Full article

Ozone micro–nano bubbles (OMNBs) are an emerging preservation technology. However, there are few reports regarding their application in controlling postharvest diseases of agricultural products. Radix astragali, as a medicinal and edible plant, is particularly vulnerable to pathogenic microorganisms during postharvest storage, which leads to diminishing the quality and commercial value. In this study, fresh R. astragali inoculated with Penicillium polonicum was treated with different concentrations (2, 3, 4, 5, 6, 8 mg/L) of OMNBs and stored at room temperature for 28 days. The results indicate that 3 mg/L OMNBs application for 8 min effectively inhibited the development of blue mold in fresh R. astragali and preserved its quality. Then, we compared the three different treatments of micro–nano bubbles (MNBs), 3 mg/L O₃, and 3 mg/L OMNBs on physiological and pathological parameters of un-inoculated fresh R. astragali during storage and analyzed the changes in the active ingredients by liquid chromatography and metabolomics. The results indicate that the 3 mg/L OMNBs treatment effectively inhibited the decline in weight loss rate, respiratory rate, firmness, browning index, and ABTS and DPPH radical-scavenging rates, as well as reduced the incidence rate and disease index of fresh R. astragali during storage. The metabolomics results suggest that the 3 mg/L OMNBs application activated the mevalonate pathway (MVA), the methylerythritol phosphate pathway (MEP), and the phenylpropanoid biosynthesis pathway to maintain the content of active ingredients such as terpenoids and flavonoids, and these findings are consistent with the results of HPLC-MS analysis. Full article

In response to the problems encountered during the pressure-driven oil recovery process in low-permeability oil reservoirs, such as slow pressure transmission, poor liquid supply, vulnerability of the reservoir to damage, and difficulties in injection and production, in order to achieve the goal of high-quality water injection development, based on the theories of rock mechanics and seepage mechanics, combined with large-scale physical model experiments, acoustic emission crack monitoring, and microscopic scanning technology, an oil reservoir and fracture model was established to conduct a feasibility analysis of pressure-driven assisted pressure reduction and enhanced injection, and it was successfully applied in the exploration and development practice of the Shengli Oilfield. The research shows the following: (1) During the pressure-driven process, the distribution of the fracture network system is relatively limited. In the early stages of the process, there will be minor fractures, but they do not communicate or activate effectively. The improvement of physical properties and pore-throat structure is negligible. As the injection flow rate increases, the effective fracture network system begins to be established, and the range of fluid coverage begins to expand. With the progress of the pressure-driven process, the hydraulic fractures gradually extend, the number of activated original fractures gradually increases, the communication area between hydraulic fractures and original fractures gradually increases, and the reservoir modification effect gradually improves. (2) Based on the compression cracking experiment of large object molds, it is concluded that generating effective micro-cracks and activating them to form efficient diversion channels is the key to pressure flooding injection. Combining the mechanical characteristics of the rock in the target layer to precisely control the injection speed and injection pressure can maximize the fracture network, thereby improving the reservoir to achieve the purpose of pressure reduction and injection increase. (3) Different pressure flooding injection parameters were set for the low-permeability oil reservoirs in the study area to simulate the fracture network expansion. Finally, it was concluded that the optimal injection speed for fracture expansion was 1.2 m³/min and the optimal total injection volume was 20,000 m³. Through research, the mechanism of pressure-driven injection and the extent of reservoir modification caused by this pressure-driven process have been enhanced in terms of understanding. Full article

Acoustic tweezers, as advanced micro/nano manipulation tools, play a pivotal role in biomedical engineering, microfluidics, and precision manufacturing. However, piezoelectric-based acoustic tweezers face performance limitations due to multi-physical coupling effects during microfabrication. This study proposes a novel approach using injection molding with embedded electronics (IMEs) technology to fabricate piezoelectric micro-ultrasonic transducers with micron-scale precision, addressing the critical issue of acoustic node displacement caused by thermal–mechanical coupling in injection molding—a problem that impairs wave transmission efficiency and operational stability. To optimize the IME process parameters, a hybrid multi-objective optimization framework integrating NSGA-II and MOPSO is developed, aiming to simultaneously minimize acoustic node displacement, volumetric shrinkage, and residual stress distribution. Key process variables—packing pressure (80–120 MPa), melt temperature (230–280 °C), and packing time (15–30 s)—are analyzed via finite element modeling (FEM) and validated through in situ tie bar elongation measurements. The results show a 27.3% reduction in node displacement amplitude and a 19.6% improvement in wave transmission uniformity compared to conventional methods. This methodology enhances acoustic tweezers’ operational stability and provides a generalizable framework for multi-physics optimization in MEMS manufacturing, laying a foundation for next-generation applications in single-cell manipulation, lab-on-a-chip systems, and nanomaterial assembly. Full article

This study proposes a novel octagonal starfish-inspired roller imprinting control for multi-space and multi-axial microstructure replication, featuring a roller printing system with a controllable mold structure for multi-space and multi-axis applications. First, a microstructure was made and a micro mold was replicated to develop and simulate a negative Poisson ratio structure as a special structure to control the polymer microstructure mold. Meanwhile, a spatial axial roller imprinting system was designed as a roller imprinting replication system for the replication and roller imprinting of microstructures to research and conduct a roller imprinting testing experiment. The experiment results showed that the multi-space and multi-axial roll imprinting processing system with a controllable mold in this research had high replication formability. The results proved that the high replication formability of the microstructure obtained through white light scanning after subsequent roller imprinting was up to 98.75%. The diameter of the microstructure reached 99.025%, and the development of this innovative system and method of new technology could obtain the expected replication formability of the microstructure. Meanwhile, good achievements were obtained through optical preliminary validation. The results of this research could provide a reference about continuous microstructure component roll forming processing for academic and technological development. Full article

Wire electrical discharge machining (WEDM) is a standard micro-manufacturing technology. In WEDM, surface roughness (SR), deviation dimension (DD), and machining time (MT) are critical requirements that impact machining quality and are affected by various input parameters. The workpiece often performs multiple machining steps (roughing, semi-finishing, and finishing) to achieve high accuracy. Each machining step directly affects the accuracy and machining time, and the preceding machining step influences the subsequent machining step parameters. Many input control parameters regulate WEDM’s performance. Thus, optimizing process control parameters at each step is essential to achieve optimal results. This study investigates the influence of input parameters, including pulse on time (Ton), pulse off time (Toff), and servo voltage (SV), on SR, DD, and MT when machining AISI D2 mold steel through rough, semi-finish, and finish cutting. Taguchi and Analysis of Variance (ANOVA) are applied to analyze and optimize this WEDM process. The results display that the optimal surface roughness values for rough, semi-finish, and finish-cut stages are 2.03 µm, 1.77 µm, and 0.57 µm, corresponding to the parameter set of Ton = 6 μs, Toff = 10 μs, and SV = 30 V; Ton = 3 μs, Toff = 15 μs, and SV = 60 V; and Ton = 21 μs, Toff = 45 μs, and SV = 60 V, respectively. In addition, in the finish-cut stage, the parameters for optimal DD of 0.001 mm (0.04%) are Ton = 3 μs, Toff = 15 μs, and SV = 40 V. In contrast, those values for optimal MT of 218 s are Ton = 3 μs, Toff = 30 μs, and SV = 40 V. All optimal input values are confirmed by the manufacturing mold and die parts. Full article

To address the challenge of imprecise micro-droplet formation control in piezoelectric jetting devices used in sand mold 3D printing and apply on-demand inkjet printing technology to sand mold manufacturing, this study first explains the working principle of a piezoelectric shear-mode printhead. A mathematical model of the droplet ejection process is then established based on Computational Fluid Dynamics (CFD). Building upon this model, numerical simulations of droplet generation, breakup, and flight are conducted by using the Volume of Fluid (VOF) model within the Fluent module of the Workbench 2020 R2 platform. Finally, under consistent driving conditions, the effects of key parameters—viscosity, surface tension, and inlet velocity—on the ejection process are investigated through simulation. Based on the results, appropriate ranges and recommended values for ink properties are determined. This study provides significant engineering value for improving the stability and precision of droplet formation in industrial sand mold 3D printing. Full article

Common surface temperature measurement techniques, when applied to monitoring the temperature of surfaces with complex morphology, suffer from reduced spatial resolution, which compromises the measurement accuracy of the system. To improve the spatial resolution of temperature measurement technology and maintain high temperature sensitivity, we designed a microscopic morphology thermometric LiDAR (MMTL) system based on the Scheimpflug principle, which realizes the real-time restoration of the 3D morphology and temperature of the surface of micro-structured objects. The 3D spatial resolution of the system is better than 3 μm. The theoretical resolution of the self-designed reflective spectrometer can reach 0.9 nm, which improves the sensitivity and accuracy of the upconversion hybrid nanomaterials thermometry based on the intensity ratio. In the wide temperature range of 373.15–508.15 K, the highest relative temperature sensitivity can reach 2.07%/K, the optimal temperature resolution is 0.0131 K, and the error is less than 1 K. Finally, the temperature change trend of the mold surface under different heating voltages is accurately restored. The MMTL system can provide accurate temperature distribution data and hotspot location identification for scenarios such as optimizing thermal management design and real-time risk monitoring, and it has application potential in industrial manufacturing and for electronic products. Full article

The traditional cement compaction process boasts notable advantages such as high strength, durability, and aesthetic appeal. However, compaction forming technology for cement products results in high carbon emissions. Consequently, it is imperative to develop low-carbon strategies for these products. This study investigates the modification of solid waste-based low-carbon sulfoaluminate cementitious material (SSCM) using mineral powder (MP) and steel slag micro powder (SSMP) under compaction forming technology. The results indicate that higher compaction pressure leads to higher early-stage strength, while the later-stage strength is primarily influenced by the degree of hydration. At a compaction pressure of 40 MPa, the one-day compressive strength of the material exceeded 70 MPa, representing a 48.31% increase compared to the control group. Under compaction forming, the hydration reaction rate decreased, but the compaction process significantly reduced porosity. Moreover, higher pressure correlated with a reduction in the proportion of harmful pores. Incorporating 25% MP and 20% SSMP increased the compressive strength by 10.66% to 113.5 MPa. According to orthogonal experimental results, the optimal molding conditions entail a 20% MP content, a 20% SSMP content, and a molding pressure of 40 MPa. The research findings can serve as a theoretical foundation for the widespread application of SSCM and compaction forming technology in practical engineering. Full article

With the development of prefabricated buildings, complex-shaped cement products, represented by heating-type elevated floors, have appeared on the market. These cement products can only be produced by the pouring method, with low efficiency and poor precision. Among the existing processing methods for preparing cement products, compression dewatering offers the greatest ability to produce cement products with complex shapes. However, the pressed mixing material comprises a plastic fresh mortar, which inherently lacks fluidity, making it difficult to completely fill the cavity of the shaped mold. Few studies have been conducted on the experimental method and design ratios of mortar for the compression dewatering process in the industry, with no effective solution. To achieve the efficient production of complex-shaped cement products, this study explored the experimental method of testing the strength and flowability of mortar formed through compression dewatering as the forming process. Mortar ratios suitable for producing complex-shaped cement products using the compression dewatering process were determined, the relationship between material rheology and product forming performance was analyzed, and the influence of the compression process on the strength and micro-properties was studied. Finally, a cement-based heating-type elevated floor forming technology was developed, offering a novel approach for the efficient forming of complex-shaped cement products. Full article

Binder jetting is the most widely implemented additive technology for the fabrication of sand molds. However, the use of furan binder-jetting technology in the production of molds for vacuum casting is hindered by the thermal destruction of the furan binder accompanied by violent gas emission that occurs during the mold heating process. This investigation explores the potential of using the molds obtained via furan binder jetting 3D printing and further impregnation in colloidal silica binder and sintering. Two distinct sands, proppant and cenosphere, were utilized in the fabrication of the mold components exhibiting different thermal properties. An examination of the structure of the initial sands and samples produced via different impregnation and sintering regimes was conducted via scanning electron microscopy with energy dispersive X-ray spectroscopy, X-ray diffractometry, thermogravimetric analysis, and micro computed tomography. Furthermore, the bending mechanical properties and linear shrinkage of the samples were determined. The experimental findings demonstrated that the specific impregnation and sintering regimes examined in this study yielded sufficient mechanical properties for the casting molds and the structure with cristobalite bridges. The mold assembly, composed of proppant and cenosphere sands-based parts, was produced, and impeller nickel-based superalloy castings were fabricated. The findings of this study demonstrate that the utilization of a furan binder-jetting technique, in conjunction with impregnation in colloidal silica binder, is a promising technology for the manufacture of high-melting-temperature alloy casting. Full article

Grain serves as an essential cornerstone for sustaining life and social stability. However, during storage grain is often invaded by mold, which leads to mildew issues. This problem diminishes nutrient content and food quality and raises safety concerns, including toxin production, which can cause serious economic losses and catastrophic market stability and national food security conditions. Accordingly, implementing effective measures to prevent and control mold is crucial for ensuring grain storage safety. This paper analyzes the molds that affect grain during storage, discussing their varieties, environmental needs, and potential hazards. It also expounds on corresponding prevention and control measures, including physical methods, chemical approaches, innovative mold inhibitors derived from microbes and plants, and micro–nano prevention and control technology. These measures demonstrate significant mold suppression by destroying the cell structure of mold or inhibiting its physiological processes. In particular, micro–nano technology enables the effective embedding and controlled release of active ingredients. It can prolong the release duration and enhance antibacterial stability, thus achieving more effective control effects. Furthermore, it can be concluded that these strategies provide a theoretical foundation to enhance the safety and efficiency of grain storage. Additionally, they assist in more effectively addressing mold-related challenges while ensuring food security. Full article

Poly(butylene adipate-co-terephthalate) (PBAT) is a promising degradable polymer for replacing non-degradable traditional plastics to mitigate pollution. However, its low softening temperature and poor hardness impede its application. Herein, PBAT and stereocomplex polylactide (sc-PLA) blends were fabricated through a melt-blending process to balance the heat resistance and mechanical strength of PBAT in this research. The effects of the PLA content and hot embossing temperature on the blend properties were comprehensively investigated. The results demonstrate that the sc-crystal content in the PBAT/sc-PLA blend increased by 493% as the PLA content rose from 10% to 30%. The blend with 15% PLLA and 15% PDLA, hot embossed at 190 °C, exhibited the highest sc-PLA crystallinity of 23.3% and the largest fraction of sc-crystallites at 66%, leading to the optimal comprehensive performance. Its Vicat softening temperature (VST) reached 92.2 °C, and a nonlinear increase trend in accordance with the power-law model between VST and the mass ratio of sc-crystal was obtained. Compared with the mechanical properties of neat PBAT, a maximum tensile yield stress of 9.7 MPa and a Young’s modulus of 82.5 MPa were achieved and improved approximately by 107% and 361%, respectively. This research offers an effective strategy for synergistically enhancing the heat resistance and mechanical strength of PBAT. Full article