RESUMO
Flame retardants are effective in protecting materials from fire but pose environmental challenges due to limited recyclability. Urgently needed for circular material economy are new flame retardants that are chemically recyclable and durable. Here, we report a new facile and scalable strategy for engineering reversible microcages with infinite chemical recyclability to starting monomers, exceptional durability, and versatile flame retardancy. This is achieved through a highly synergistic hierarchical assembly of easily obtainable phosphoric acid and Cu2+ monomers. By leveraging dynamic reversible assembly networks, microcages can be circularly and infinitely dissociated into starting monomers via eco-friendly pH adjustment. Remarkable recovery rates of 92% for phosphoric acid and 96.2% for Cu2+ monomers are achieved, while the separated virgin matrix undergoes conventional chemical recycling, facilitating reformulation and seamless reintroduction into new supply chains as needed. Notably, when integrated with matrix-like surfaces, microcage clasp matrices tightly engage through in situ formed interfacial locking structures, showcasing outstanding flame-retardant efficiency, prolonged durability in hydrothermal aging, and extensive applicability across diverse polymeric materials such as polyurethane, epoxy resin, and polycarbonate. This study emphasizes a novel, straightforward, and scalable chemical platform, utilizing reversible interfacial locking engineering, for the development of flame retardants that are not only infinitely recyclable but also durable and broadly applicable.
RESUMO
Background: Improving basic public health services efficiency becomes priority to guarantee its sustainability for Chinese government. This study aimed to explore basic public health services efficiency and its influencing factors between urban and rural in Shandong Province, China, providing policy implications to improve efficiency. Methods: This research assessed basic public health services efficiency of 54 districts (representing urban) and 83 counties (representing rural) in Shandong, China, from 2014 to 2019. The data were obtained from Medical Management Service Center of Shandong Health Commission and Statistical Yearbooks. Input variables were subsidy funds, public health staffs and material expenditures. Output variables were assessment indicators covered all service contents from national standard. The data envelopment analysis and panel tobit regression were used to measure efficiency scores and efficiency influencing factors. Results: Basic public health services efficiency scores of urban were higher than those of rural during 2014 to 2019. Scale efficiency change and technological change promoted basic public health services total factor productivity change of urban and rural respectively. Panel tobit regression indicated that proportion of health expenditures in general public budget expenditures (P<0.01), subsidy funds (P<0.01), public health personnel expenditures (P<0.01) and the frequency of professional health institutions' guidance (P<0.01) were positively associated with efficiency in both urban and rural. The number of primary medical and health institutions and public health personnel were positively associated with urban (P<0.01), but those did not affect rural (P>0.10). Conclusion: To improve basic public health services efficiency, urban should focus on health resource structure, especially increasing primary medical and health institutions and public health personnel. Rural should expand the input scale, paying more attention to subsidy funds and public health personnel expenditures. The government should also care strengthening the guidance to primary medical and health institutions from professional health institutions.
