Inspired by the fire-making tool (the Iroquois pump drill), a new two-degree-of-freedom (2-DOF) string-driven rotational energy harvester (SREH) is proposed, which can efficiently harvest energy from ambient vibrations at ultra-low frequency (0.2 Hz). The proposed SREH is composed of a 2-DOF string-driven rotor and a magnet-coil transduction unit. The 2-DOF string-driven rotor consists of a rotor, a lid, an elastic string, an inelastic string, and support springs, capable of effectively converting ultra-low frequency vibrations into high-speed rotation (328 rpm). The magnet-coil transduction unit can transfer the kinetic energy to electricity. Numerical and experimental results both show that the proposed SREH can deliver stable electrical outputs under harmonic excitation (1-5 Hz). Under an excitation frequency of 5 Hz and an excitation amplitude of 7.5 mm, the proposed harvester can generate a power of 1.55 mW. Furthermore, with flywheel energy storage mechanism, the proposed harvester can generate a power of 0.64 mW under an impact excitation of 0.2 Hz. In addition, under manual pressing excitation (approximately 6 Hz), the proposed device is capable of generating a power of 1.54 mW and rapidly charging a 1 mF capacitor from 0 V to 1.58 V within approximately 8 s. The results exhibit the great potential of the string-driven harvester for efficiently scavenging ultra-low frequency vibration energy.
The efficient and clean utilization of biomass energy constitutes a key means to mitigating the energy crisis, improving the ecological environment, and promoting the transformation of the energy structure. Accordingly, in this study, two types of bimetallic catalysts were prepared via the impregnation method: ZrO2-supported Ni-Mo and Ni-Co catalysts, and tetrapropylammonium hydroxide (TPAOH)-modified H-form zeolite Socony Mobil-5 (T1.5)-supported Ni-Mo catalysts. These were then employed to catalyze the pyrolysis of cotton stalks (CSs) for upgrading bio-oil quality. Ultimately, catalyst characterization results confirmed that for the T1.5 catalyst modified with TPAOH and loaded with Ni-Mo, the proportion of strong acid sites decreased, whereas that of the medium-strong acid sites increased. Specifically, the Brunauer-Emmett-Teller specific surface area of Ni1-Mo3/T1.5 was 10.4 times that of Ni1-Mo3/ZrO2, with the micropore area of the former accounting for 97.0 % of the total specific surface area. Additionally, catalytic performance analyses indicated that the pyrolysis activation energy of the CS decreased with increasing Mo loading for all catalysts. After addition of the Ni1-Mo3/ ZrO2 and Ni1-Mo3/T1.5 catalysts, the average activation energy of CS pyrolysis decreased significantly from 177.68 to 127.43 and 119.26 kJ/mol, respectively. Overall, Ni1-Mo3/T1.5 exhibited the highest relative hydrocarbon content of 57.1 %, within which the relative content of aromatics was 42.5 %. This result indicates its potential as a catalyst for bio-oil upgrading.
Against the backdrop of consumer utility loss caused by information asymmetry in fresh products and the impact of freshness preservation investment on supply chain performance, this paper examines how fresh produce suppliers and retailers can enhance consumer cognition by adopting Digital Trust Technology, which integrates AI and blockchain. It further analyzes the interactive effects of different cooperation modes and pre-sale strategies. Based on Stackelberg game theory, a two-echelon supply chain consisting of one supplier and one retailer is constructed. Optimal decisions and profits are derived through backward induction, and a pre-sale profit-sharing contract is designed to coordinate the supply chain. The study finds that the Digital Trust Technology enhances the competitiveness of the reselling mode, making it feasible in regions where no consensus previously existed, while simultaneously narrowing the consensus region for the agency selling mode. Under the agency selling mode, the supplier, who holds pricing power, is always willing to adopt the technology and raise the pre-sale price, thereby achieving a win–win outcome with the retailer. In contrast, under the reselling mode, although the retailer actively adopts the technology, the supplier lacks sufficient motivation to cooperate. Without coordination, the strategic conflict region accounts for most of the parameter space, and consensus can be achieved only under specific commission rates and pre-sale ratios. By designing a profit-sharing contract, the consensus region for the reselling mode can be significantly expanded, thereby achieving Pareto improvement. Furthermore, under the reselling mode, when the cost of preservation is high, it is actually beneficial to retailers and the entire supply chain.
Despite high-voltage lithium metal batteries (HVLMBs) offering promising prospects for achieving high-energy-density batteries, their development remains severely hindered by the poor compatibility between conventional carbonate-based electrolytes and high-voltage cathodes, as well as severe safety issues. To address these challenges, this study designed a perfluorinated composite gel polymer electrolyte (F-CGPE) with a "rigid-flexible" architecture using Polyvinylidene fluoride-hexafluoropropylene/Li6.75La3 Zr1.75Nb0.25O12 composite nanofiber (PLCNF) scaffold and fluorine-containing liquid electrolyte (FLE). The full penetration and strong interaction between PLCNF and FLE form continuous and uninterrupted ion transport channels; meanwhile, the strong electronegativity of fluorine atoms further weakens the solvation effect with lithium ions (Li+ ) and promotes ion transport. As a result, the prepared F-CGPE exhibits a high ionic conductivity of 8.64 & times; 10-4S cm-1 and a lithium transference number (tLi +) of 0.69, respectively. Moreover, F-CGPE induces rapid and uniform deposition of Li+ and constructs a stable interface layer with abundant lithium fluoride (LiF) component, effectively inhibiting lithium dendrite growth and accelerating interface ion transport. The LFP//F-CGPE//Li cell delivers an initial discharge specific capacity of 125.4 mAh g-1 at 0.5 C, the capacity retention rate is above 100% after 150 cycles. Further increasing the rate to 5 C and the active material loading to similar to 5 mg cm-2, the cell still maintains a capacity retention rate of 90.8% after 300 cycles. Even within a wide range of low temperatures, it demonstrates excellent cold resistance capability. Its capacity retention rate exceeds 100% at 0 degrees C after 100 cycles. Notably, high-voltage NCM622//Li and NCM811//Li cells exhibit capacity retention rates of 96.1% and 96.9%, respectively, after 50 cycles at 0.5 C. Therefore, the designed F-CGPE demonstrates the potential application value of this integrated "perfluorinated framework-electrolyte synergy" design in the next-generation energy storage systems. (c) 2026 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.
Efficient and stable conversion of carbon sources within the reactor is a core prerequisite for the large-scale production and engineering application of carbon nanotube fibers (CNTFs). However, existing single-channel injection processes are limited by the thermodynamic constraint of low-entropy local concentration enrichment, leading to multi-field mismatch and catalyst sulfur poisoning, which in turn results in low carbon nanotube (CNT) yield and uneven CNTF diameter distribution. Based on the concept of entropy regulation, this study proposes a dual-channel multi-field synergistic matching strategy. By achieving spatial decoupling, thiophene is uniformly distributed locally within the reactor, thereby suppressing excessive catalyst poisoning, optimizing the matching conditions of concentration field, temperature field, and flow field during the preparation process, and effectively breaking through the technical bottleneck of CNTF growth. Experimental results show that, compared with the traditional single-channel injection process, this strategy can increase CNTF yield by approximately 80.1% under the Fe10S system constructed with an appropriate thiophene concentration, and improve the carbon conversion efficiency from 3.47% to 6.26%. Under higher catalyst precursor feed conditions, its advantages become even more significant, with a yield increase of up to 114.7% and a high production rate (6.2 mg/min). This study provides an innovative reactor engineering design approach for the continuous, stable, and large-scale preparation of high-performance CNTFs.
