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Organic persistent luminescence is usually emitted from synthesized materials containing π units (aromatic rings, double bonds, etc.). It is challenging but desirable to develop organic materials from renewable resources with tunable persistent luminescence to reduce environmental impact. Herein, we proposed an effective method to enhance the luminescence of cellulose, the most abundant natural renewable material free of π units. It was found that removing the crystal water in cellulose would increase the compactness of molecular packing and stabilize the hydroxyl clusters of polysaccharide chains, consequently leading to significant enhancement of phosphorescence with lifetime up to subseconds. This dehydration induced luminescence enhancement was found in not only purified cellulose but also cellulose-contained substances such as papers, cottons, and many other plant tissues. This indicated easier access to cellulose-based luminescence materials without chemical purification. In addition, label-free time-resolved luminescence imaging of plant tissues was achieved on a smartphone-based apparatus, since endogenous cellulose is distributed extensively in plants. Compared with synthetical luminophores, cellulose is a renewable and biodegradable source abundant in nature, not only readily available but also environmentally friendly. We believe this method may be used to develop other sustainable organic luminescence materials with a lack of π units for various optical applications.

There are few reports on the material transformation and dominant microorganisms in the process of greening waste (GW) composting. In this study, the target microbial community succession and material transformation were studied in GW composting by using MiSeq sequencing and PICRUSt tools. The results showed that the composting process could be divided into four phases. Each phase of the composting appeared in turn and was unable to jump. In the calefactive phase, microorganisms decompose small molecular organics such as FA to accelerate the arrival of the thermophilic phase. In the thermophilic phase, thermophilic microorganisms decompose HA and lignocellulose to produce FA. While in the cooling phase, microorganisms degrade HA and FA for growth and reproduction. In the maturation phase, microorganisms synthesize humus using FA, amino acid and lignin nuclei as precursors. In the four phases of the composting, different representative genera of bacteria and fungi were detected. Streptomyces, Myceliophthora and Aspergillus, maintained high abundance in all phases of the compost. Correlation analysis indicated that bacteria, actinomycetes and fungi had synergistic effect on the degradation of lignocellulose. Therefore, it can accelerate the compost process by maintaining the thermophilic phase and adding a certain amount of FA in the maturation phase.

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Natural renewable resources with long-lived persistent luminescence have attracted wide attention since many of these luminescence materials have low toxicity and are environmentally friendly. However, many of these materials lack conjugated groups such as aromatic rings, leading to weak absorption and low luminescence quantum yields. Herein, we proposed an effective method to enhance the luminescence of cellulose, a natural polymer free of conjugated groups. Halide salts were doped in cellulose for inducing absorption transition from halide ions to polysaccharide chains and increasing intersystem crossing through the external heavy-atom effect. In addition, divalent metal ions doped in cellulose could reduce nonradiative relaxations through electrostatic interactions. The phosphorescence quantum yield of dried cellulose doped with MgBr 2 could reach 5%, significantly higher than that of many other natural renewable resources. The results provided a simple and effective method for tuning the persistent luminescence of cellulose, which could be easily applied to optical encryption on cellulose-based textiles and papers. This method may be extended widely for enhancing the clusteringtriggered emission of many other nonconjugated organic materials in luminescence bioimaging, anticounterfeiting, and encryption.