Science China Technological Sciences最新文献

This paper presents a discussion on the method, mechanism, and application of adhesive hydrogel in enhancing epidermal signal, focusing on the interface between hydrogel and skin. Due to its excellent conductivity and high adaptability to the skin, the hydrogel is exceptionally suitable for detecting human-machine interfaces, particularly epidermal electromyographic signals. However, the detection of the high epidermal signal is hindered by the gap and low adhesion between hydrogel and skin. This paper addresses these challenges by introducing approaches to reduce the interface gap and increase interface adhesion, thereby enabling the development of hydrogel-based epidermal signal detection arrays with enhanced resolution and detection performance.

Peeling strength can comprehensively reflect slider track safety and is crucial in car seat safety assessments. Current methods for determining slider peeling strength are primarily physical testing and numerical simulation. However, these methods encounter the potential challenges of high costs and overlong time consumption which have not been adequately addressed. Therefore, the efficient and low-cost surrogate model emerges as a promising solution. Nevertheless, currently used surrogate models suffer from inefficiencies and complexity in data sampling, lack of robustness in local model predictions, and isolation between data sampling and model prediction. To overcome these challenges, this paper aims to set up a systematic framework for slider track peeling strength prediction, including sensitivity analysis, dataset sampling, and model prediction. Specifically, the interpretable linear regression is performed to identify the sensitivity of various geometric variables to peeling strength. Based on the variable sensitivity, a distance metric is constructed to measure the disparity of different variable groups. Then, the sparsity-targeted sampling (STS) is proposed to formulate a representative dataset. Finally, the sequentially selected local weighted linear regression (SLWLR) is designed to achieve accurate track peeling strength prediction. Additionally, a quantitative cost assessment of the supplementary dataset is proposed by utilizing the minimum adjacent sample distance as a mediator. Experimental results validate the efficacy of sequential selection and the weighting mechanism in enhancing localization robustness. Furthermore, the proposed SLWLR method surpasses similar approaches and other common surrogate methods in terms of prediction performance and data quantity requirements, achieving an average absolute error of 3.3 kN in the simulated test dataset.

In natural water, microplastics (MPs) inevitably undergo microbial colonization to form biofilm, while the effect of biofilm formation on the photoaging of MPs remains unknown. This study systematically investigated the photoaging behavior of disposable box-derived polypropylene (PPMPs) and polystyrene (PSMPs) mediated by formed biofilm in water. After incubating in Weihe water samples for 105 d, the biofilm was validated to form in PPMPs and PSMPs, with higher formation in PSMPs. In particular, biofilm formation inhibited the photoaging of PPMPs and PSMPs, with an 11.1% and 50.6% decrease in photo-oxidation compared to their virgin counterparts after 20 d of ultraviolet (UV) irradiation. Moreover, the photoaging route of MPs such as the reaction priority of functional groups (e.g., C–H, C=O, and benzene ring) was altered, indicating the important role of biofilm formation in the photoaging process of MPs. The protective effect of the biofilm was mainly caused by the role of optical light filters that absorbed UV energy by sacrificing themselves. Also, as the main attacker on MPs, the production of reactive oxygen species (ROS, mainly ¹O₂ and •OH) was inhibited by biofilm, which was mainly responsible for the decreased photoaging of MPs. This study revealed the important role of biofilm in the photoaging process of MPs and suggested a higher resistance of (micro)plastics in natural water than that in the laboratory using pure MPs, which contributed to a deeper understanding of the environmental fate and pollution of MPs.

The long-wave infrared band (8–14 µm) is essential for several applications, such as infrared detection, radiative cooling, and near-field heat transfer. However, according to Kirchhoff’s law, the intrinsic balance between thermal absorption and emission limits the further improvement of photon energy conversion and thermal management. Thus, breaking Kirchhoff’s balance and achieving nonreciprocal thermal radiation in the long-wave infrared band are necessary. Most existing designs for nonreciprocal thermal emitters rely on grating or photonic crystal structures to achieve nonreciprocal thermal radiation at narrow peaks, which are relatively complex and typically realize bands larger than 14 µm. Here, a sandwich structure consisting of an epsilon-near-zero (ENZ) magneto-optical layer (MOL), a dielectric layer (DL), and a metal layer is proposed to achieve a strong nonreciprocal effect in the long-wave infrared band, which is mainly attributed to the strengthening of the asymmetric Berreman mode by the Fabry–Perot cavity. In addition, the impact of the incident angle, DL thickness, and DL refractive index on the nonreciprocal thermal radiation has been investigated. Moreover, by replacing the ENZ MOL with the gradient ENZ MOL, the existence of the DL can further improve the nonreciprocity of the broadband nonreciprocal thermal radiation. The proposed work promotes the development and application of nonreciprocal energy devices.

Measuring the complex permittivity of ultrathin, flexible materials with a high loss tangent poses a substantial challenge with precision using conventional methods, and verifying the accuracy of test results remains difficult. In this study, we introduce a methodology based on a back-propagation artificial neural network (ANN) to extract the complex permittivity of paper-based composites (PBCs). PBCs are ultrathin and flexible materials exhibiting considerable complex permittivity and dielectric loss tangent. Given the absence of mature measurement methods for PBCs and a lack of sufficient data for ANN training, a mapping relationship is initially established between the complex permittivity of honeycomb-structured microwave-absorbing materials (HMAMs, composed of PBCs) and that of PBCs using simulated data. Leveraging the ANN model, the complex permittivity of PBCs can be extracted from that of HMAMs obtained using standard measurement. Subsequently, two published methods are cited to illustrate the accuracy and advancement of the results obtained using the proposed approach. Additionally, specific error analysis is conducted, attributing discrepancies to the conductivity of PBCs, the homogenization of HMAMs, and differences between the simulation model and actual objects. Finally, the proposed method is applied to optimize the cell length parameters of HMAMs for enhanced absorption performance. The conclusion discusses further improvements and areas for extended research.

Emerging contaminants (ECs) of significant concern are widely distributed throughout the environment due to various industrial practices and human activities. Given the alarming ecological threats and potential risks that ECs pose to human health and aquatic life, even at trace concentrations, it is imperative to develop innovative technologies to effectively address these challenges. The biophotoelectrochemistry (BPEC) system, which integrates microbial cells with photosensitizers for solar-to-chemical conversion, holds great potential as an efficient strategy for the removal of ECs. In this review, we provide new insights into the BPEC system for the ECs treatment by systematically summarizing the classification, sources, and environmental occurrence of ECs. Additionally, we explore the research progress and degradation mechanisms in ECs removal with BPEC. Finally, the current challenges and future perspectives for the applications of the BPEC system in the ECs treatment are analyzed. This review aims to promote the development of BPEC technology for ECs treatment, offering a promising prospect for environmental remediation, circular economy, and clean-energy production.

To enhance the cooling capacity of traditional microchannels for high heat flux electronic devices, a microchannel design with staggered semi-elliptical ribs is proposed in this paper. Through numerical simulations, the flow characteristics of the designed microchannel are compared with those of a smooth one, and the effects of rib width (W_r), rib height (H_r), and rib length (L_r), on the thermal-hydraulic performance are investigated under laminar flow conditions. The results show that the periodically arranged ribs induce periodic vortices within the microchannel, effectively promoting fluid mixing and enhancing heat transfer. W_r and H_r have similar effects on microchannel performance, with an increase in them leading to an enhanced thermal performance at the expense of deteriorated hydraulic performance. Additionally, L_r has a comparatively weaker influence, with both the heat transfer and flow resistance initially growing with increasing L_r and then declining. To strike a balance between the two performances, a multi-objective optimization on the three geometrical parameters is conducted at a Reynolds number (Re) of 440. Combined with simulation data, artificial neural networks are trained as surrogate models, and a multi-objective genetic algorithm is employed to derive the Pareto front. Using the TOPSIS decision-making method, an optimal compromise solution is determined as W_r = 0.2415 mm, H_r = 0.0976 mm, and L_r = 0.6486 mm. Performance testing on the optimized microchannel reveals that it exhibits high heat transfer, middle flow resistance, and excellent overall performance, with the performance evaluation criterion (PEC) falling between 1.572 and 1.723 within the Re range of 220–660.

Ultra-high-performance seawater sea-sand concrete (UHPSSC) presents a prospective solution to address the natural resource shortage in marine infrastructure construction. To eliminate the corrosion risk of steel fibers and broaden the applicability of UHPSSC, this study investigates the mechanical properties and free chloride ion content as well as microstructures of UHPSSC reinforced with superfine stainless wires (SSWs) under natural curing. The results indicate that 1.5% SSWs can remarkably improve the flexural strength and toughness of UHPSSC by 127% and 1724%, respectively, and mitigate the long-term strength degradation of UHPSSC. The strong interfacial bond between SSW and UHPSSC improves the compactness of UHPSSC, thus reducing the growth space for Ca(OH)₂ crystals and swelling hydration products generated by sulfate and magnesium ions. This can be supported by the observed reduction in the Ca/Si ratio of C–S–H gels, CH crystal orientation index, and porosity. Moreover, through mechanisms such as pull-out, rupture, overlapping network, and internal anchor interface, SSWs effectively prevent microcrack growth and propagation, transforming single long-connected microcracks into multiple-emission microcracks centered on SSW. Additionally, the free chloride ion content of the composites at 28 and 180 d meets the ACI 318-19 standard requirements for concrete exposed to seawater. This compliance is attributed to the chloride immobilization facilitated by Friedel’s salt and C–S–H gels within the interfaces around SSWs and sea-sand. Consequently, SSWs-reinforced UHPSSC exhibits considerable potential for applications in sustainable marine infrastructures, demanding long-term mechanical properties and high durability.

Sewage sludge is a major source of fecal pathogens in the environment, and its application to land can result in a significant release of these pathogens into the soil. While conditioning treatments are crucial for improving the dewatering process of sludge, their impact on the presence and behavior of fecal pathogens in soil remains unclear. This study aims to assess four extraction methods for recovering fecal pollution indicators from soil amended with unconditioned and conditioned sludge. The indicators include Escherichia coli (EC), human-specific HF183 Bacteroides (HF183), human adenovirus (HAdV), human BK polyomavirus (BKPyV), human JC polyomavirus (JCPyV), and cross-assembly phage (crAssphage). This study also examines how soil moisture content affects the decay of these fecal pollution indicators in soil amended with raw sludge and investigates the influence of conditioning treatments with cationic polyacrylamide (PAM), Fenton’s reagents, Fe[III]/CaO on their persistence in soil. The results indicated that the direct extraction method was the most effective and unbiased for recovering fecal pollution indicators from sludge-amended soil compared with the three elution-concentration methods. All fecal pollution indicators, except HAdV, remained stable under dry soil conditions, while high soil moisture content (48.39%–53.14%) slowed the decay rates of these indicators. During the application of sludge to soil, effective control of fecal pollution indicators was observed, with JCPyV and HAdV becoming undetectable within a short period. The log reduction values of HF183, BKPyV, and crAssphage ranged from 0.1 to 2.8 logs after 30 d of cultivation. The application of conditioned sludge, especially Fenton’s reagent-conditioned sludge, resulted in a reduction in human fecal contamination in the receiving soil. Therefore, implementing appropriate conditioning methods, such as using Fenton’s reagent, can effectively mitigate the health risks associated with fecal pathogens.

The solid electrolyte interphase (SEI) is widely recognized as a critical factor leading to the capacity fading of lithium-ion batteries (LIBs). Although SEI stress-related mechanical failure caused by the expansion or contraction of active materials upon cycles is well documented, previously reported SEI components and overpotential varying phenomena due to SEI stress and their effects on the electrochemical performance are poorly understood. Here, we establish a quantitative correlation between capacity fading and the SEI stress by considering its effects on side reactions, especially SEI component evolution, in a multiscale mechanical-electrochemical coupling model. Furthermore, the capacity fading behaviors of two typical cells (Li[NiMnCo]O₂ as the cathode, and graphite and silicon as the anode, respectively) were adopted as numerical examples to demonstrate its potential utility and applications. Stress within the SEI was indeed found to play a predominant role in the capacity fading of the graphite and silicon anodes, resulting in 27% and 69% of the total capacity loss after 200 and 100 cycles at 1 C, respectively. This study provides valuable mechanical insights into the variations of SEI properties related to the capacity degradation and SEI optimization and design for LIBs.