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.

This manuscript introduces an effective method for preparing a magnetic solid acid and its application in the synthesis of diphenoic acid. The prepared catalyst (Fe@NC-SO3H, Co@NC-SO3H, or Ni@NC-SO3H) was a sulfonated N-doped carbon nanotube encapsulating Fe, Co, or Ni nanoparticles, respectively. Remarkably, the magnetic core was formed in situ during the calcination of the catalyst. The metal nanoparticles gave the catalyst excellent magnetic separation performance. The −SO3H group could be capable of efficiently catalyzing the condensation reaction of levulinic acid with phenol to diphenolic acid with a 95% yield. Significantly, this encapsulated structure of the catalyst can effectively improve the stability of the catalyst, and this catalyst still obtained good stability in acidic reaction conditions, which was proved by recycled experiments and a series of catalyst characterizations.

In this paper, we investigate the problem of repeater insertion for low power under a given timing budget. We propose a novel repeater insertion algorithm to compute the optimal repeater number and width in the discrete solution space, as defined by a given repeater library. Using our algorithm, we show that rounding the solution under the continuity assumption to the closest discrete solution candidate may result in suboptimal designs, or it may even fail to find an existing solution. Given a certain tolerance to the degradation of repeater power dissipation, we address two practical and highly important questions: (1) How coarse could the repeater size granularity be? (2) What range should the repeater size be in?Experimental results demonstrate the high effectiveness of the proposed scheme and provide valuable insights into repeater library design. Our approach achieves up to 23% power reduction in comparison to rounding-based approaches. With a 4% power degradation tolerance, repeater size granularity as coarse as 8λ can be used, reducing the library size by more than 87%. For interconnects with various wire lengths and timing targets, our investigation reveals that the range of optimal repeater sizes for low-power is limited, indicating that a low-cost small-size repeater library, if well designed, is adequate to provide high quality repeater insertion solutions.