Crystalline and soluble 1D linear conjugated polymers (LCPs) have garnered considerable interest as cost-effective and efficient metal-free electrocatalysts for the oxygen reduction reaction (ORR) due to their high ex...
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Crystalline and soluble 1D linear conjugated polymers (LCPs) have garnered considerable interest as cost-effective and efficient metal-free electrocatalysts for the oxygen reduction reaction (ORR) due to their high exposure of catalytic sites and ease of processing. However, difficulties remain in achieving excellent ORR performance for 1D LCPs by conventional molecular design. Herein, it is demonstrated the utilization of quinoidal units as a promising strategy to develop 1D LCPs for ORR. The incorporation of quinoidal unit not only results in polymers with strong inter- and intra-molecular interactions and low-lying LUMO (lowest unoccupied molecular orbital) energy levels, but also provides polymers with good crystallinity and commendable charge carrier mobilities. The electronic properties of these polymers are fine-tuned through the introduction of additional heteroatoms and/or substituents in the monomers and comonomers to understand and optimize their ORR catalytic activity. Evaluation of their catalytic performances reveals a remarkable half-wave potential and limiting current density of up to 0.74 V (vs reversible hydrogen electrod) and 7.50 mA cm-2, respectively. Notably, these performances are achieved without the addition of carbon nanomaterials as support. This study offers a new insight into the design of highly efficient metal-free organic electrocatalysts. 1D linear conjugated polymers containing a quinoidal unit are synthesized as the metal-free electrocatalysts for oxygen reduction reaction. These polymers show good film-forming properties, well-ordered structures, and excellent charge transport abilities. As a result, they exhibit high oxygen reduction reaction catalytic activities without the need for carbon nanomaterials as support. image
In this study, nitrogen-doped carbon material (N-PC-d) derived from coal tar pitch using dicyandiamide as N source was successfully synthesized, exhibiting outstanding catalytic performance in the activation of peroxy...
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In this study, nitrogen-doped carbon material (N-PC-d) derived from coal tar pitch using dicyandiamide as N source was successfully synthesized, exhibiting outstanding catalytic performance in the activation of peroxymonosulfate (PMS) for the degradation of Orange G (OG). By optimizing key parameters such as PMS dosage, NPC dosage, nitrogen source, pH, anions, and PS source, the optimal N-PC-d/PMS system achieved a degradation rate 1.45 times higher than that of the PC/PMS system within a broad pH range (2.0-10.0). Through electron paramagnetic resonance (EPR) and quenching experiments, it was found that singlet oxygen (1O2) was the predominant species accountable for OG degradation, while reactive oxygen species (ROS), including superoxide (O2 & sdot;-), hydroxyl radicals (& sdot;OH), and sulfate radicals (SO4 & sdot;-), played auxiliary roles. Moreover, the structure-activity relationship analysis revealed that functional groups such as C--C, C--O, and pyridine N were mainly involved in PMS activation. The degradation mechanism of OG was further elucidated by high-performance liquid chromatography-mass spectrometry (HPLC-MS). This research presented a cost-efficient N-doped porous carbon material for environmental remediation and provides more profound insights into the mechanisms of PMS activation by N doped carbon-based materials.
In this paper, we prove the quantitative version of the Alexandrov theorem for capillary hypersurfaces in the half-space, which generalizes Julin-Niinikoski’s result [18] to the capillary case. The proof is based on ...
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A coal tar pitch-based porous carbon adsorbent (CPA) was synthesized through a straightforward method involving the heating of a mixture of KOH and coal tar pitch (CTP). This CPA exhibited a high surface area of 1811....
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A coal tar pitch-based porous carbon adsorbent (CPA) was synthesized through a straightforward method involving the heating of a mixture of KOH and coal tar pitch (CTP). This CPA exhibited a high surface area of 1811.2 m2 g-1 and a large pore volume of 0.94 cm3 g-1 when prepared with a CTP to KOH mass ratio of 1:4 at 800 degrees C. Parameters such as the heating temperature and activator dose were optimized to enhance the adsorption efficiency. The prepared CPA was extensively characterized by SEM, XRD, FTIR, and BET measurements. Notably, CPA presented a distinct adsorption performance for Orange G (OG), achieving a maximum adsorption capability of 449.7 mg g-1. Kinetic studies indicated that the adsorption process followed the pseudo-second-order model, while the adsorption isotherm data demonstrated that both chemical and physical interactions favored OG adsorption. Thermodynamic analysis revealed that the adsorption of OG on CPA was spontaneous and exothermic and increased the entropy. Density functional theory (DFT) calculations provided insights into the adsorption mechanism, highlighting electrostatic interactions, hydrogen bonds, and pi-pi interactions as the dominant processes governing OG adsorption onto the adsorbent.
Customer retention is an important basis for International Trade shows to obtain sustained competitive advantage, and the retention of multinational exhibitors is largely influenced by cultural heterogeneity. This stu...
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Customer retention is an important basis for International Trade shows to obtain sustained competitive advantage, and the retention of multinational exhibitors is largely influenced by cultural heterogeneity. This study intends to explore the influence of cultural distance on the retention of multinational exhibitors based on Hofstede's national culture model. It is based on an analysis of 4476 multinational exhibitors from 7 famous international trade shows in China through web crawler technology. The results reveal that total cultural distance has a significant positive effect on the retention of multinational exhibitors. However, different sub-dimensions under cultural distance may have different effects. In terms of sub-dimensions including power distance, individualism and uncertainty avoidance, the greater the cultural distance, the easier it is to retain customers. As for sub-dimensions of long term orientation, the estimated results display an opposite tendency. The findings contribute to the literature and have practical implications for international trade shows' service and management.
The conversion of stearic acid into linear hydrocarbons is a crucial step in advancing sustainable biofuels and biochemicals. Herein, we developed a series of cobalt-based catalysts (referred to as Co/C@TSC) using met...
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The conversion of stearic acid into linear hydrocarbons is a crucial step in advancing sustainable biofuels and biochemicals. Herein, we developed a series of cobalt-based catalysts (referred to as Co/C@TSC) using metal-organic frameworks (MOFs) as precursors and supporting them on biochar derived from natural tung shells (TSC). Tung shells, a byproduct of the tung oil extraction process, are widely available. The as-designed Co/C@TSC catalyst effectively deoxygenated stearic acid via decarbonylation/decarboxylation (DCO x ) processes, achieving a conversion of 78.5% and hydrocarbon product selectivity of 90%, specifically heptadecane and heptadecene. Our detailed analysis showed that the addition of biochar support improved the spatial distribution of cobalt species (with a high surface concentration of Co0) and enhanced the adsorption of reactants, thus boosting catalytic activity. Additionally, in situ DRIFTS analysis confirmed that the stearic acid deoxygenation process involved the intermolecular dehydration of stearic acid molecules. Experiments with different reaction substrates revealed that the stearic anhydride was a key reaction intermediate during the deoxygenation process. This study introduces a novel catalyst made from dual carbon-supported nonprecious metals, presenting a promising method for transforming stearic acid into valuable hydrocarbon products.
This study aims to comprehensively investigate the reinforcement mechanism of the tunnel support structure and its supporting characteristics in layered and weak rock tunnels. Uniaxial compressive tests were carried o...
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This study aims to comprehensively investigate the reinforcement mechanism of the tunnel support structure and its supporting characteristics in layered and weak rock tunnels. Uniaxial compressive tests were carried out to study the mechanical and deformation characteristics of anchored rock with the system anchor bolt and the steel floral pipe. Besides, a three-point bending test of the steel-concrete composite beam was conducted to investigate the bending capacity of the grilles and I-beams. The experiment showed the following results: (1) The anchor bolt achieved the anchoring effect by improving the stress state and the strength of the surrounding rock. The improvement of the anchorage strength to the surrounding rock was reflected by the effect of the compression zone of preload, the healing effect of the anchorage agent on the surrounding rock, and the reinforcement effect of the anchor bolt on the density and strength of the anchor bolt. (2) By the CT scanning of the anchored samples after the experiment, it was found that the crack was blunted and arrested within the anchorage zone, and the crack-arresting effect was related to the range of the anchorage zone. The larger the anchorage zones, the better the crack-arresting effect. (3) The steel arch could effectively improve the ability of concrete antideformation. Compared with the lattice girder, the coordination ability of steel arch and concrete deformation was relatively weak. Its coordinate deformation stage was shorter than that of the lattice girder and earlier into the debonding stage. However, the stiffness of the steel arch and concrete was greater than that of the lattice girder after debonding and showed a strong bearing capacity.
Synaptic transistors are pivotal for hardware-level neuromorphic computing. However, the lack of switching behavior diversity has limited the implementation of advanced computing tasks, which are constrained by tradit...
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Synaptic transistors are pivotal for hardware-level neuromorphic computing. However, the lack of switching behavior diversity has limited the implementation of advanced computing tasks, which are constrained by traditional interfacial or uncontrollable materials engineering. Here, a universal planar p-n junction structure is devised, with rational alignment of energy levels between crosslinkable p-type poly(indacenodithiophene-alt-benzothiadizole)-based conjugated polymer with hydroxyl groups at the ends of its side chains (OH-IDTBT-10%) and different n-type conjugated polymers, fabricated through efficient solution processing. This structure enables reconfigurable switching of p-type and n-type carrier transport by modifying the transistor architecture, along with significant non-volatile memory and synaptic plasticity. By strategically adjusting crosslinkers, a large memory window up to 48.5 V is achieved, sustained performance over 500 cycles, and a diverse array of synaptic behaviors modulated by electrical pulses. The underlying mechanism involves quantum well-like structures and discrete physical charge traps at the bilayer interface. The versatility of the strategy is proven across different n-type polymer systems. An artificial neural network (ANN) constructed by these devices affords a remarkably high facial recognition accuracy of 97.58% using the Yale Face Database with minimized training epochs of 200. This design provides an opportunity for high performance hardware with diverse synaptic behaviors in advanced neuromorphic computing.
The governance of service ecosystem needs to balance efficiency and fairness to promote the sustainable development of the system, making it an important topic. However, service entities in the service ecosystem have ...
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ISBN:
(纸本)9798350368567;9798350368550
The governance of service ecosystem needs to balance efficiency and fairness to promote the sustainable development of the system, making it an important topic. However, service entities in the service ecosystem have autonomy and engage in dynamic game with governance strategies, leading to governance challenges. To address this issue, we model the governance process as a repeated sequential game between the governance algorithm and service entities, and propose a novel two-level learning algorithm. This algorithm considers the learning evolution of service entities and the co-evolutionary of the governance algorithm, using reinforcement learning to learn effective governance strategies while also considering the response function of service entities to balance efficiency and fairness. Combining the ideas of bilevel optimization and online learning, this algorithm effectively balances exploration (understanding the service entities' responses function) and exploitation (choosing efficient actions). We apply the algorithm to a classic service ecosystem, the ride-hailing service system, and empirically demonstrate its effectiveness in the governance task of order dispatching.
In this paper,we prove an optimal Heintze-Karcher-type inequality for ani-sotropic free boundary hypersurfaces in general convex *** equality is achieved for anisotropic free boundary Wulff shapes in a convex *** appl...
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In this paper,we prove an optimal Heintze-Karcher-type inequality for ani-sotropic free boundary hypersurfaces in general convex *** equality is achieved for anisotropic free boundary Wulff shapes in a convex *** applica-tions,we prove Alexandrov-type theorems in convex cones.
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