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The rapid development of green products, such as electric vehicle (EV) batteries, has brought about challenges in recycling and remanufacturing. To help tackle these challenges, in this research, we investigate how process innovation affects green product remanufacturing. Specifically, using game-theoretic models, we analyze process innovation strategies for green product remanufacturing in a closed-loop supply chain consisting of an upstream supplier and a downstream manufacturer. In these models, process innovation is implemented individually (i.e., non-cooperative mechanisms) by either the supplier or the manufacturer, or jointly (i.e., cooperative mechanism) by both firms. Our main findings are threefold. Firstly, process innovation can effectively improve remanufacturing performance while increasing the recovery rate of the manufacturer. Secondly, although the cooperative mechanism is always beneficial to the supplier, the supply chain and the environment, it may not be favourable by the manufacturer. Lastly, by extending the main models, we show that government subsidies can incentivise the manufacturer to adopt the cooperative mechanism, thereby achieving a win–win situation.

In order to attain competitive advantage, it is of high importance for firms to move towards sustainability. In practice, an efficient sustainable closed-loop supply chain (SCLSC) can reduce the negative effects of hazardous wastes and consequently improve the environmental dimension of sustainability. Besides the environmental dimension, the social aspect of sustainability can be achieved through initiating corporate social responsibility and enhancing social welfare of customers. Different from the existing literature, this paper proposes an analytical coordination model to not only cover all three dimensions of sustainability in a SCLSC but also to align different decisions made in competitive forward and reverse logistics. The proposed SCLSC is modeled under decentralized, centralized, and coordinated decision-making structures considering different game behaviors in the forward and reverse links. The results reveal that the proposed two-way two-part tariff (TWTPT) contract is of high benefit to the sustainable CLSC as it is able to simultaneously enhance the environmental, economic, and social performances. To be more precise, the proposed model improves the collection rate, consumer surplus, social welfare, and profits of all CLSC members. In addition, our findings demonstrate the applicability and efficiency of the proposed TWTPT contract in motivating the agents of both competitive forward and reverse chains to participate in the coordination scheme.

Chemical recycling of polymers is critical for improving the circular economy of plastics and environmental sustainability. Traditional thermoset polymers have generally been considered permanently crosslinked materials that are difficult or impossible to recycle. Herein, we demonstrate that by activating ‘dormant’ covalent bonds, traditional polycyanurate thermosets can be recycled into the original monomers, which can be circularly reused for their original purpose. Through retrosynthetic analysis, we redirected the synthetic route from forming conventional C–N bonds via irreversible cyanate trimerization to forming the C–O bonds through reversible nucleophilic aromatic substitution of alkoxy-substituted triazine derivatives by alcohol nucleophiles. The new reversible synthetic route enabled the synthesis of previously inaccessible alkyl-polycyanurate thermosets, which exhibit excellent film properties with high chemical resistance, closed-loop recyclability and reprocessing capability. These results show that ‘apparently dormant’ dynamic linkages can be activated and utilized to construct fully recyclable thermoset polymers with a broader monomer scope and increased sustainability. Alkyl and aryl polycyanurate networks have now been prepared through polymerization of diols and substituted triazines via a dynamic S N Ar reaction. When treated with excess mono alcohol or phenol, the polycyanurate networks can be depolymerized into the starting monomers, which can be separated and reused, thus achieving closed-loop recycling.

Focusing on one class of nonlinear systems with input saturation, the adaptive fuzzy dynamic event-triggered control problem is successfully solved. A dynamic event-triggered mechanism is adopted to save the communication burden of the system, and is integrated into the controller design process based on the backstepping technique. For handling the asymmetric input saturation, an auxiliary system with the same order as the considered system is constructed. Analysis problems caused by unknown continuous functions are efficiently tackled by applying the approximation theory of fuzzy logic systems. It is proven that all the signals of the resulting closed-loop system are bounded via Lyapunov stability analysis. Both numerical and practical simulations are presented to demonstrate the effectiveness of the theoretical results.

To reduce environmental pollution and reliance on fossil resources, polyethylene terephthalate as the most consumed synthetic polyester needs to be recycled effectively. However, the existing recycling methods cannot process colored or blended polyethylene terephthalate materials for upcycling. Here we report a new efficient method for acetolysis of waste polyethylene terephthalate into terephthalic acid and ethylene glycol diacetate in acetic acid. Since acetic acid can dissolve or decompose other components such as dyes, additives, blends, etc., Terephthalic acid can be crystallized out in a high-purity form. In addition, Ethylene glycol diacetate can be hydrolyzed to ethylene glycol or directly polymerized with terephthalic acid to form polyethylene terephthalate, completing the closed-loop recycling. Life cycle assessment shows that, compared with the existing commercialized chemical recycling methods, acetolysis offers a low-carbon pathway to achieve the full upcycling of waste polyethylene terephthalate. The recycling of polyethylene terephthalate is of utmost importance to reduce environmental pollution and reliance on fossil resources however, the existing methods do not process colored or blended polyethylene terephthalate materials. Here, the authors demonstrate the acetolysis of waste polyethylene terephthalate into terephthalic acid and simultaneous acidic degradation of dyes and additives

This paper is concerned with event-triggered H ∞ control of sampled-data systems. Its novelties lie in three aspects: (i) A novel accumulated-state-error-based event-triggered scheme is introduced by comparing the integral of the state error from t k to t with the system state sampled at t k . This condition works well due to the fact that the so-called Zeno behaviour does not occur. (ii) A novel Lyapunov functional is constructed to establish a criterion to ensure some certain H ∞ performance of the closed-loop system. This Lyapunov functional is dependent on the integral of the state error involved in the event-triggered scheme. (iii) Under the event-triggered sampling scheme, suitable state-feedback controllers can be designed rather than be given a priori. Moreover, a self-triggered implementation of the proposed event-triggered sampling scheme is presented as well. Finally, a batch reactor model and an inverted pendulum system are given to demonstrate the effectiveness of the proposed method.

Purpose This paper explains in details the rationale behind the choice of the end-of-life allocation approach in the European Commission Product Environmental Footprint (PEF) and Organisational Environmental Footprint (OEF) methods. The end-of-life allocation formula in the PEF/OEF methods aims at enabling the assessment of all end-of-life scenarios possible, including recycling, reuse, incineration (with heat recovery) and disposal for both open- and closed-loop systems in a consistent and reproducible way. It presents how the formula builds on existing standards and how and why it deviates from them. Methods Various end-of-life allocation approaches and formulas, mainly taken not only from/based on existing environmental impact assessment methods and/or standards but also one original linearly degressive approach, were analysed against a predetermined set of criteria, reflecting the overall aim of the PEF/OEF methods. This set of criteria is physical realism, distribution of burdens and benefits in a product cascade system and applicability. Besides the qualitative analysis, the various formulas were implemented for several products and for different scenarios regarding recycled content and recyclability to check the robustness of the outcomes, exemplary expressed for the Global Warming Potential impact category. Results and discussion As reaching physical realism was impossible at both the product and overall product cascade system level by any of the end-of-life approaches analysed, one of both had to be prioritised. The paper explains in details why a product level approach was preferred in the context of the PEF/OEF methods. In consequence, allocation of the end-of-life processes which are related to more than one product in a product cascade system is needed and should be carefully considered as it has a major influence on the results and decision taking. Conclusions A formula taking into account the number of recycling cycles of a material was identified as preferred to reach physical realism and to allocate burdens and benefits of repeatedly recycling of a material over the different products in a product cascade system. However, this approach was not selected for the PEF/OEF methods as data on the number of recycling cycles was insufficiently available (for the time being) for all products on the market and hence fails the criterion of “applicability”. This explains why, instead, a formula based on the 50:50 approach—allocating shared end-of-life processes equally between the previous and subsequent product—was selected for the PEF/OEF methods.

Sustainable battery recycling is essential for achieving resource conservation and alleviating environmental issues. Many open/closed-loop strategies for critical metal recycling or direct recovery aim at a single component, and the reuse of mixed cathode materials is a significant challenge. To address this barrier, here we propose an upcycling strategy for spent LiFePO 4 and Mn-rich cathodes by structural design and transition metal replacement, for which uses a green deep eutectic solvent to regenerate a high-voltage polyanionic cathode material. This process ensures the complete recycling of all the elements in mixed cathodes and the deep eutectic solvent can be reused. The regenerated LiFe 0.5 Mn 0.5 PO 4 has an increased mean voltage (3.68 V versus Li/Li + ) and energy density (559 Wh kg –1 ) compared with a commercial LiFePO 4 (3.38 V and 524 Wh kg –1 ). The proposed upcycling strategy can expand at a gram-grade scale and was also applicable for LiFe 0.5 Mn 0.5 PO 4 recovery, thus achieving a closed-loop recycling between the mixed spent cathodes and the next generation cathode materials. Techno-economic analysis shows that this strategy has potentially high environmental and economic benefits, while providing a sustainable approach for the value-added utilization of waste battery materials. Direct recycling of critical battery materials bring promise but a challenge for the mixed cathode chemistries. Here, the authors report a sustainable upcycling approach, transforming degraded LiFePO 4 and Mn-rich cathodes into a high-voltage polyanionic material with an increased energy density and economic value.

PurposeThis paper presents a systematic literature review of the various aspects of reverse logistics (RL) and closed-loop supply chains (CLSC) in implementing and achieving circular economy (CE) motives. CE is identified as a method of embracing imperishability into the economic structure, helping shift from a linear to a condition leading to ecological and social benefits.Design/methodology/approachSystematic literature was used to review a total of 80 peer-reviewed articles are included in the study and covers different concepts related to the implementation of CE, such as cost-saving, network design, sustainable RL, waste management and extended producer responsibility.FindingsThe findings reveal that the research in the domain is in a growing phase, and in recent years, a lot of attention has been given by researchers across the globe. However, further research is required in crucial areas for the adoption of CE, such as retail reverse logistics, pharmaceutical industries and resource recycling industry.Practical implicationsThe study discusses the business needs and solutions for industries. Key enablers and barriers are listed along with the main activities involved in each sector in CLSC. Managers can design a pathway to decide which lever to use to overcome a particular challenge.Originality/valueThe work contributes theoretically by developing research themes in RL and CLSC practices applied to CE. It also provides theoretical and practical implications of the study, which can be used as a signboard for further research.

A closed‐loop system that can mini‐invasively track blood glucose and intelligently treat diabetes is in great demand for modern medicine, yet it remains challenging to realize. Microneedles technologies have recently emerged as powerful tools for transdermal applications with inherent painlessness and biosafety. In this work, for the first time to the authors' knowledge, a fully integrated wearable closed‐loop system (IWCS) based on mini‐invasive microneedle platform is developed for in situ diabetic sensing and treatment. The IWCS consists of three connected modules: 1) a mesoporous microneedle‐reverse iontophoretic glucose sensor; 2) a flexible printed circuit board as integrated and control; and 3) a microneedle‐iontophoretic insulin delivery component. As the key component, mesoporous microneedles enable the painless penetration of stratum corneum, implementing subcutaneous substance exchange. The coupling with iontophoresis significantly enhances glucose extraction and insulin delivery and enables electrical control. This IWCS is demonstrated to accurately monitor glucose fluctuations, and responsively deliver insulin to regulate hyperglycemia in diabetic rat model. The painless microneedles and wearable design endows this IWCS as a highly promising platform to improve the therapies of diabetic patients. A fully integrated wearable closed‐loop system (IWCS) based on microneedle‐iontophoresis platform is developed for in situ diabetic sensing and treatment. This IWCS is demonstrated to accurately monitor glucose fluctuations and responsively deliver insulin to regulate hyperglycemia. The painless microneedles and wearable design endow this IWCS as a highly promising platform to improve the therapies of diabetic patients.