RESUMEN
A time-domain slicing (TDS) optical frequency domain reflectometry is proposed for large strain sensing with better spatial resolution. Compared with the conventional frequency domain slicing (FDS) method, the TDS with a Burg spectrum estimation is capable of enhancing the similarity of a local spectrum under large strain and mostly suppressing the fake peaks during the strain resolving. The experimental results demonstrated that it enables measurements of strain ranging from 600 to 4200⠵ε with a spatial resolution of 2.4â mm and a narrow optical frequency scanning range of only 10â nm. Moreover, the measurement accuracy is improved by six times by decreasing the root mean square error (RMSE) from 8.6611 to 1.3396⠵ε without any hardware modification.
RESUMEN
The heterogeneous monomers obtained from plastic waste degradation are unfavorable for PET recondensation and high-value derivative synthesis. Herein, we developed an efficient chemical-enzymatic approach to convert mixed plastic wastes into homogeneous mono-2-hydroxyethyl terephthalate (MHET) without downstream purification, benefiting from three discovered BHETases (KbEst, KbHyd, and BrevEst) in nature. Towards the mixed plastic waste, integrating the chemical K2 CO3 -driven glycolysis process with the BHETase depolymerization technique resulted in an MHET yield of up to 98.26 % in 40â h. Remarkably, BrevEst accomplished the highest BHET hydrolysis (~87 % efficiency in 12â h) for yielding analytical-grade MHET compared to seven state-of-the-art PET hydrolases (18 %-40 %). In an investigation combining quantum theoretical computations and experimental validations, we established a MHET-initiated PET repolymerization pathway. This shortcut approach with MHET promises to strengthen the valorization of mixed plastics, offering a substantially more efficient and energy-saving route for PET recycling.
RESUMEN
Although considerable research achievements have been made to address the plastic crisis using enzymes, their applications are limited due to incomplete degradation and low efficiency. Herein, we report the identification and subsequent engineering of BHETases, which have the potential to improve the efficiency of PET recycling and upcycling. Two BHETases (ChryBHETase and BsEst) are identified from the environment via enzyme mining. Subsequently, mechanism-guided barrier engineering is employed to yield two robust and thermostable ΔBHETases with up to 3.5-fold enhanced kcat/KM than wild-type, followed by atomic resolution understanding. Coupling ΔBHETase into a two-enzyme system overcomes the challenge of heterogeneous product formation and results in up to 7.0-fold improved TPA production than seven state-of-the-art PET hydrolases, under the conditions used here. Finally, we employ a ΔBHETase-joined tandem chemical-enzymatic approach to valorize 21 commercial post-consumed plastics into virgin PET and an example chemical (p-phthaloyl chloride) for achieving the closed-loop PET recycling and open-loop PET upcycling.
