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Infection is a major obstacle to wound healing. To enhance the healing of infected wounds, dressings with antibacterial activities and multifunctional properties to promote wound ...healing are highly desirable. Herein, gelatin-grafted-dopamine (GT-DA) and polydopamine-coated carbon nanotubes (CNT-PDA) were used to engineer antibacterial, adhesive, antioxidant and conductive GT-DA/chitosan/CNT composite hydrogels through the oxidative coupling of catechol groups using a H2O2/HRP (horseradish peroxidase) catalytic system. The addition of the antibiotic doxycycline endowed the hydrogels with antimicrobial activity to treat infected full-thickness defect wounds. Additionally, CNT-PDA endowed these hydrogels with an excellent photothermal effect, leading to good in vitro and in vivo antibacterial activities against Gram-positive and Gram-negative bacteria. The catechol group and polydopamine imparted tissue adhesiveness, and the hemostatic and antioxidant abilities of these hydrogels were also investigated. The porosity, degradability, swelling, rheological, mechanical, and conductive behaviors of these hydrogels were finely regulated by changing the concentration of CNT-PDA. Hemolysis and cytocompatibility tests using L929 fibroblast cells confirmed the good biocompatibility of these hydrogels. The wound closure, collagen deposition, histomorphological examination and immunofluorescence staining results demonstrated the excellent effects of these hydrogels in an infected full-thickness mouse skin defect wound. In summary, the adhesive antibacterial and conductive GT-DA/chitosan/CNT hydrogels showed great potential as multifunctional bioactive dressings for the treatment of infected wounds.
Environmental, social, and governance (ESG) performance has increasingly become the most pressing concern for governments, social organizations, companies, and other stakeholders. Understanding macro ...ESG behavior can assist governments in achieving their sustainable development goals (SDGs). In this paper, we investigate whether the macro ESG index of OPEC and non‐OPEC oil‐producing countries over the period 1990–2020 exhibits mean‐reversion behavior and whether the external shocks are transient or permanent. By conducting a series of advanced panel stationarity tests, we find that the macro ESG indices of the sample countries do not exhibit mean‐reversion and that an external shock has a permanent effect. We also identifies the yearly structural breaks that occur in the sample countries and attempts to explain why. Our research suggests that governments should use policy interventions to counteract external shocks to macro ESG behavior so as to achieve sustainable development and long‐term performance stability.
•A comprehensive review of researches on gas starvation issue of PEM fuel cell.•Include causes, severe consequences, diagnostic methods and mitigation measures.•Summarize the variable methods and ...compare their performance in different aspects.•Provide guidance to the diagnose methods, system control strategy and structure design.
The short service life of fuel cell is a key problem that restricts the commercialization of fuel cell vehicles. Many scholars have found that gas starvation is one of the most important causes of the proton exchange membrane fuel cell lifetime decay, which leads to a series of severe consequences such as carbon support corrosion, cell reversal and output performance degradation. However, accurate diagnosis and effective mitigation of fuel cell gas starvation are not achieved currently. Gas starvation is a condition that the reaction gas of proton exchange membrane fuel cell working in the sub-stoichiometric state. In this paper, we will study the causes, severe consequences, diagnostic methods and mitigation measures of the gas starvation in proton exchange membrane fuel cells through previous literature review. This research is aim to provide guidance to the diagnose methods, to optimize the system control strategy and structure design and to contribute to the studies which are focus on prolong the proton exchange membrane fuel cell lifetime.
•Mesoscale discrete element modeling is an effective way to investigate RAC’s mechanical behaviors.•RAC’s cracking process is sharply affected by the relative strength of old mortar to new ...mortar.•Old mortar content degenerates RAC’s mechanical properties considerably.•Too strong ITZ adhesion enhances RAC’s mechanical properties only slightly.•The best way to improve RAC’s mechanical properties appears to be removing the old mortar layer.
This paper presents a computational study to underline how the uniaxial behaviors of recycled aggregate concrete (RAC) are affected by various factors. Particularly, RAC is modeled using a discrete element method (DEM) wherein each phase of RAC (i.e., new and old aggregates, mortars, and in-between interfaces) is represented explicitly. By doing so, the mesoscopic cracking process of RAC can be accurately traced. The development, calibration and validation of the modeling method are presented. Then a parametric study is conducted, considering the following major factors: the attributes of new mortar and old mortar, the old mortar content, the severity of damages produced in manufacture of recycled aggregate (RA), and the bond property of interfacial transition zones (ITZs). It is shown that the relative strength of old mortar to new mortar plays a vitally important role in defining the failure mechanism of RAC. Specifically, if old mortar is stronger than new mortar, cracking initiates at their interfaces. By contrast, for relatively weak old mortar incipient cracks arise instead from inside of RA particles, localizing mostly at old aggregate–old mortar ITZs. Yet in some extreme cases with very weak old mortar, early damages are trapped in old mortar alone. Those different origins of crack formation affect the macro-level behavior of RAC considerably. Moreover, the relative amount of old mortar has a significant effect—a higher content of such constituent reduces both strength and modulus of RAC, but concurrently delays the onset of mesoscale cracking. Results also show that a weak ITZ between RA and new mortar confers a pronounced reduction in RAC’s mechanical properties; conversely, the properties’ enhancement from improving those ITZs is capped though. This research illustrates how the developed DEM-based approach can be conducive to a better understanding of RAC’s mechanical response to uniaxial loadings.
The rechargeable zinc–air battery (ZAB) is a promising energy storage technology owing to its high energy density and safe aqueous electrolyte, but there is a significant performance bottleneck. ...Generally, cathode reactions only occur at multiphase interfaces, where the electrocatalytic active sites can participate in redox reactions effectively. In the conventional air cathode, the 2D multiphase interface on the surface of the gas diffusion layer (GDL) inevitably results in an insufficient amount of active sites and poor interfacial contact, leading to sluggish reaction kinetics. To address this problem, a 3D multiphase interface strategy is proposed to extend the reactive interface into the interior of the GDL. Based on this concept, an asymmetric air cathode is designed to increase the accessible active sites, accelerate mass transfer, and generate a dynamically stabilized reactive interface. With a NiFe layered‐double‐hydroxide electrocatalyst, ZABs based on the asymmetric cathode deliver a small charge/discharge voltage gap (0.81 V at 5.0 mA cm−2), a high power density, and a stable cyclability (over 2000 cycles). This 3D reactive interface strategy provides a feasible method for enhancing the air cathode kinetics and further enlightens electrode designs for energy devices involving multiphase electrochemical reactions.
A 3D multiphase reactive interface strategy is proposed to enhance the reaction kinetics in the air cathode of a rechargeable zinc–air battery. As a proof of concept, an asymmetric air cathode is designed, which exhibits an increased amount of accessible active sites, accelerated mass transfer, and a dynamically stabilized reactive interface.
Flexible quasi‐solid‐state sodium ion batteries featuring their low‐cost, high safety and excellent mechanical strength have attracted widespread interest in the field of wearable electronic devices. ...However, the development of such batteries faces great challenges including the construction of interfacial compatible flexible electrode materials and addressing the high safety demands of electrolyte. Here selenium‐vacancies regulated bimetallic selenide heterojunctions anchored on waste cotton cloth‐derived flexible carbon cloth (FCC) with robust interfacial C‐Se‐Co/Fe chemical bonds as a flexible anode material (CCFSF) is proposed by ultrafast microwave pyrolysis method. Rich selenium vacancies and CoSe2/FeSe2−x heterostructures are synchronously formed that can significantly improve ionic and electronic diffusion kinetics. Additionally, a uniform carbon layer coating on the surface of Se‐deficient heterostructures endows it with outstanding structural stability. The flexible cathode (PB@FCC) is also fabricated by directly growing Prussian blue nanoparticles on the FCC. Furthermore, an advanced flexible quasi‐solid‐state Na‐ion pouch cell is assembled by coupling CCFSF anode, PB@FCC cathode with P(VDF‐HFP)‐based gel polymer electrolyte. The full cell not only demonstrates excellent energy storage performance but also robust mechanical flexibility and safety. The present work offers an effective avenue to achieve high safety flexible energy storage device, promoting the development of flexible wearable electronic devices.
An ultrafast solvent‐free microwave method is developed to prepare carbon‐coating CoSe2/FeSe2−x heterostructure with enriched selenium vacancies, which is grown on the surface of waste cloth‐derived carbon cloth. When used as flexible anode, it displays excellent properties in half/full sodium‐ion batteries. This preparation strategy can be also extended to develop other advanced electrodes in metal‐ion batteries.
With the economic transformation and regional economic restructuring of China, there is a significant inter-regional transfer trend of industries among the eastern, central, western and northeastern ...regions. The industrial transfer is able to change the spatial distribution of regional energy intensity by affecting the regional industrial structure, thus impacting the convergence of energy intensity. This paper established a spatial Durbin panel model, and used the relevant data of thirty administrative regions of China from 2004 to 2017 to empirically study the impacts of industrial transfer on regional energy intensity. The results showed that: (1) As a whole, the energy intensity of China's regions was low in the southeast region and high in the northwest region, and there was a significant positive spatial autocorrelation among the energy intensity of different regions. (2) There was β-convergence in the regional energy intensity. It indicated that, on the one hand, the differences in the energy intensity of China's different regions were being gradually narrowed; on the other hand, the energy intensity of each region would converge to its own steady state. (3) The industrial transfer and economic development could promote the convergence of the regional energy intensity.
•China's economic transition and regional economic restructuring promoted industrial transfer.•The regional energy intensity showed a decreasing trend from northwest to southeast.•Industrial transfer could promote the convergence of energy intensity.•A spatial Durbin panel model was used to prove the regional energy intensity convergence of China.
Lithium–sulfur (Li–S) batteries are deemed as future energy storage devices due to ultrahigh theoretical energy density. Cathodic polysulfide electrocatalysts have been widely investigated to promote ...sluggish sulfur redox kinetics. Probing the surface structure of electrocatalysts is vital to understanding the mechanism of polysulfide electrocatalysis. In this work, we for the first time identify surface gelation on disulfide electrocatalysts. Concretely, the Lewis acid sites on disulfides trigger the ring‐opening polymerization of the dioxolane solvent to generate a surface gel layer, covering disulfides and reducing the electrocatalytic activity. Accordingly, a Lewis base triethylamine (TEA) is introduced as a competitive inhibitor. Consequently, Li–S batteries with disulfide electrocatalysts and TEA afford high specific capacity and improved rate responses. This work affords new insights on the actual surface structure of electrocatalysts in Li–S batteries.
Surface gelation on disulfide electrocatalysts in Li–S batteries is identified for the first time. The gel layer, formed through the solvent polymerization triggered by the Lewis acid sites, covers the active electrocatalytic sites and renders reduced redox kinetics. Herein, a Lewis base triethylamine is introduced to suppress the surface gelation and promote the electrocatalytic activity of disulfide electrocatalysts.
After application in electric vehicles, spent LiFePO4 (LFP) batteries are typically decommissioned. Traditional recycling methods face economic and environmental constraints. Therefore, direct ...regeneration has emerged as a promising alternative. However, irreversible phase changes can significantly hinder the efficiency of the regeneration process owing to structural degradation. Moreover, improper storage and treatment practices can lead to metamorphism, further complicating the regeneration process. In this study, a sustainable recovery method is proposed for the electrochemical repair of LFP batteries. A ligand‐chain Zn‐complex (ZnDEA) is utilized as a structural regulator, with its ─NH─ group alternatingly facilitating the binding of preferential transition metal ions (Fe3+ during charging and Zn2+ during discharging). This dynamic coordination ability helps to modulate volume changes within the recovered LFP framework. Consequently, the recovered LFP framework can store more Li‐ions, enhance phase transition reversibility between LFP and FePO4 (FP), modify the initial Coulombic efficiency, and reduce polarization voltage differences. The recovered LFP cells exhibit excellent capacity retention of 96.30% after 1500 cycles at 2 C. The ligand chain repair mechanism promotes structural evolution to facilitate ion migration, providing valuable insights into the targeted ion compensation for environmentally friendly recycling in practical applications.
The introduction of the ligand chain within the Zn complex dynamically modulates the variational structure, enlarging the main framework of LFP and expediting the de‐intercalation of Li+. This process revitalizes the composition, structure, and electrochemical performance of LFP, restoring them to levels comparable to that of newly produced LFP even under severe degradation conditions during the operation of regenerated batteries.
