Rui Li

Porous biochar is a functional filler for fiber-based composites. However, its fine particle size, weak affinity toward lignocellulosic fibers, and highly adsorptive pore structure lead to low retention and competitive AKD adsorption, creating a retention–sizing trade-off that limits composite performance. To overcome this challenge, a hierarchical encapsulation–asymmetric bridging flocculation (EABF) strategy integrating cationic starch (CS) and cationic polyacrylamide (CPAM) through sequential interfacial assembly was developed. In this strategy, CS was first adsorbed onto biochar surfaces to form a passivating encapsulation layer that partially shielded porous adsorption sites and regulated interfacial charge characteristics. Subsequently, CPAM served as an asymmetric bridging agent, preferentially linking CS-modified biochar with straw fibers to generate enlarged flocs with enhanced biochar–fiber association. The optimized assembly pathway increased biochar retention and total retention by 84.77% and 25.70%, respectively. Simultaneously, the dry tensile index, sizing degree, and water contact angle improved by 35.14%, 35.02%, and 64.13%, respectively, demonstrating concurrent enhancement of mechanical strength, surface hydrophobicity, and air barrier properties. Mechanistically, surface passivation and asymmetric bridging synergistically suppressed competitive AKD adsorption while strengthening filler–fiber connectivity, thereby coordinating particle-scale interfacial regulation with network-scale structural assembly. This work establishes a scalable interfacial engineering strategy for overcoming performance trade-offs associated with porous fillers and advances the development of sustainable high-performance fiber-based materials.

Soil adhesion and abrasive wear severely degrade the performance and service life of soil-covering rollers in no-tillage seeders, particularly in the heavy clay black soil regions of Northeast China. To address the critical issues of soil adhesion and wear on soil-covering rollers used in no-tillage seeders within black soil regions, this study presents a surface engineering strategy that integrates a bionic micro-texture with a functional composite coating. Inspired by the crescent-shaped pits on the body surface of Procambarus clarkii, a bionic texture was designed and combined with a PTFE/PDMS/TiO₂ composite coating. Key parameters were optimized using response surface methodology, yielding a TiO₂ mass fraction of 6%, coating thickness of 40 μm, remaining texture depth of 50 μm, and texture spacing of 250 μm. A prototype was fabricated and evaluated through orthogonal field experiments in two distinct soil environments. In clay soil (15–25% moisture content), soil moisture and vertical load significantly influenced anti-adhesion performance, with recommended operating parameters of 600 N vertical load and a speed range of 10.8–14.4 km·h⁻¹. In sandy soil (8–18% moisture content), vertical load and operating speed had significant effects on wear resistance, with optimal parameters identified as 600 N vertical load and 10.8 km·h⁻¹. Verification tests confirmed stable low-adhesion and low-wear performance under varying moisture conditions. Compared to conventional and PTFE-coated rollers, the bionic roller reduced soil adhesion by 82.62% and 74.02%, respectively, in high-moisture clay soil, and reduced wear loss by 36.81% and 28.97%, respectively, in dry sandy soil. These results demonstrate that the synergistic “structure–material” design, which leverages stress dispersion and storage from the bionic texture alongside low surface energy and enhanced wear resistance from the composite coating, offers a promising approach for improving the durability and performance of soil-engaging agricultural components.

Engineering surfaces operating in harsh environments frequently require simultaneous resistance to abrasive wear and the minimization of interfacial adhesion. Achieving this dual functionality through a single surface modification strategy remains challenging. This study presents a novel hybrid approach combining bionic laser surface texturing with a polytetrafluoroethylene/polydimethylsiloxane/TiO₂ nanocomposite coating to synergistically enhance both wear resistance and hydrophobicity of 65Mn steel. Crescent-shaped micro-dimples, inspired by the exoskeleton of Procambarus clarkii, were fabricated via a femtosecond laser. A composite coating containing hydrophobically modified TiO₂ nanoparticles was subsequently deposited. Single-factor experiments identified effective parameter ranges. A four-factor, five-level central composite rotatable design combined with response surface methodology was employed to systematically optimize texture depth, texture spacing, TiO₂ mass fraction, and coating thickness. The results demonstrate that textures with a depth of less than 100 μm and spacing less than 400 μm effectively homogenize surface stress distribution. RSM analysis revealed that TiO₂ content and texture depth predominantly influence hydrophobicity, while texture spacing overwhelmingly controls wear mass loss. Significant interactions between coating and texture parameters were identified. The optimal parameter combination was determined as: 6% TiO₂, 40 μm coating thickness, 50 μm texture depth, and 250 μm texture spacing. Under these conditions, the surface achieved a superhydrophobic contact angle of 152.1° and a low-wear mass loss of 8.9 mg. Validation tests yielded values of 150.8° and 9.3 mg, respectively, confirming model reliability. The synergistic mechanism involves textures acting as debris reservoirs and stress distributors, while the coating provides a low-surface-energy, hardened top layer that minimizes adhesion and facilitates a rolling–sliding contact mode. This work provides a robust, optimized framework for designing multifunctional surfaces for demanding tribological applications.

Biodegradable agricultural films manufactured with straw serve as a viable substitute for plastic films, effectively addressing the issue of white pollution. However, existing biodegradable straw fiber films exhibit insufficient mechanical properties, primarily characterized by their susceptibility to fracture damage. To address this issue, a novel method for the preparation of film raw materials was proposed, which employs the synergistic treatment of bioenzymes and a single screw extruder, with the aim of enhancing the mechanical properties of the film. The method begins with the application of microbial agents to pretreat the straw, for improving its fiber morphology and inducing beneficial physicochemical structural changes. Subsequently, single screw extrusion technology is employed to further enhance the quality of the straw fibers and the mechanical performance of the film. The bio-mechanical pulp produced with this method demonstrated an increase in the crystallinity index (CrI) from 50.33% to 60.78%, while the degree of polymerization (DP) decreased from 866.51 to 749.60. Furthermore, the tensile strength, tear strength, and burst strength of the fiber covering film increased by 35.74%, 16.22%, and 11.65%, respectively, which meet the mechanical durability requirements for farmland mulching. This research effectively mitigates agricultural white pollution by converting agricultural waste straw into biodegradable mulch film, which promotes the recycling of straw resources. This study presents a novel method with significant potential application value for the production of bio-pulping in the paper industry.

Accurately estimating soil moisture (SM) without direct measurements poses significant challenges due to nonlinear interactions in meteorological variables and the lagged response of SM to precipitation. This study evaluates two approaches: the auto-regressive integrated moving average (ARIMA) model for one-day-ahead SM forecasting and a K-means clustering-based multilayer perceptron (K-MLP) for real-time SM estimation at depths of 5 cm, 20 cm, and 50 cm in Changbai Mountain region. Although the K-MLP model outperformed the MLP model, achieving a maximum R² of 0.728, its estimation accuracy remains suboptimal. By contrast, the ARIMA model effectively leveraged SM persistence, achieving high accuracy in one-day-ahead forecasting. Specifically, the ARIMA (0, 1, 6), ARIMA (1, 1, 2), and ARIMA (2, 1, 1) models yield R² values of 0.9677, 0.9853, and 0.9684 and RMSE values of 0.02 m³·m³, 0.015 m³·m³, and 0.006 m³·m³ at depths of 5 cm, 20 cm, and 50 cm, respectively. This study explores ARIMA’s robustness in short-term SM forecasting and its adaptability to dynamic meteorological conditions, offering potential applications in agricultural water management and ecological monitoring.

In order to sustain control over soybean root rot, wheat-straw-fiber-based mulch film (WFM) coated with carbendazim (C) and chitosan (CS) mixture (C-CS-WFM) were prepared through bar coating technology. The Box–Behnken design method was employed to investigate the effects of chitosan concentration, wet film thickness, and carbendazim loading on the dry tensile strength (DTS), wet tensile strength (WTS), and air permeance (AP) of C-CS-WFM. Eventually, the optimization process parameters were determined as follows: a chitosan concentration of 1.83–2.39%, a wet film thickness of 18–24 μm, and a carbendazim loading of 0.05–0.12 g/m². These parameters achieved the desired physical properties of C-CS-WFM, i.e., the DTS is not less than 3.5 kN/m, the WTS is not less than 0.8 kN/m, and the AP does not exceed 2.1 μm/(Pa·s). The results showed that after the introduction of the C-CS coating, the DTS and WTS of C-CS-WFM were enhanced by 11.4% and 14.9%, respectively. In contrast, the AP was reduced by 15.6%. FT-IR analysis indicated that carbendazim was embedded in the C-CS composite material without any chemical interaction. Through SEM and sustained-release kinetic analysis, it was found that the sustained-release mechanism of C-CS-WFM conformed to the Ritger–Peppas kinetic model, and its release mechanism was the physical diffusion and matrix erosion. The results of the in vitro antifungal test and pot experiment demonstrated that C-CS-WFM could effectively inhibit the growth of Fusarium solani and promote the growth of plants. This study provided new ideas for the comprehensive prevention and control of soybean root rot.