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The fluorescence properties were first probed for wood prehydrolysis liquor (PHL) in the present study. Besides fluorescence concentration quenching and pH effects, the excitation wavelength-dependent photoluminescence properties were also observed at excitation from 360 to 430 nm. In order to explore the inducement of visible fluorescence, the fluorescence analysis was performed for acid-soluble lignin; X-ray diffraction and Raman spectroscopy were performed for the PHL solids and revealed that graphitic carbon in the form of carbon nanodots (CNDs) exists in lignocellulosic PHL. Transmission electron microscopy and atomic force microscopic analyses further characterized the morphology of the graphitic carbon. These CNDs have an average diameter of 5.04 ± 0.89 nm and two forms of lattice spacing of 0.23 nm and 0.34 nm; the average height is 1.73 ± 0.71 nm. The discovery of the fluorescence and CNDs in lignocellulosic PHL will greatly widen its promising applications. [ABSTRACT FROM AUTHOR]

Three-dimensional carbon foam (CF) has been widely employed as a conductive framework for preparing self-supporting supercapacitor electrodes. Herein, based on the spin-drying mechanism of washing machine, a spin-coating method is developed to prepare carbon foam@graphene oxide (CF@GO) composites, in which a special centrifugation tube containing a macroporous shelf is used to separate the foam block and residual GO suspension during centrifugation. The GO fractions in CF@GO composites are controlled easily by tuning the spin speeds. As freestanding electrodes in two-electrode supercapacitors, the CF@GO-4500 (4500 rpm, 1.2 wt% GO) and CF@RGO-1000 electrodes (1000 rpm, 3.2 wt% GO) exhibit the specific capacitances of 159 Fg−1 (258 mF cm−2) and 180 Fg−1 (297 mF cm−2) at 0.5 Ag−1, respectively, which are much higher than those of CF and CF@GO-4 or CF@RGO-4 sample (15.3 wt% GO) prepared by a conventional soaking-freeze-drying method. The results show that a few GO/RGO sheets loading in CF framework exhibit an enhanced electrochemical performance in supercapacitor, rather than filling much GO/RGO. [ABSTRACT FROM AUTHOR]

This paper proposes a novel filtering strategy characterized by an impulsive differential system. It provides an alternative solution to the problem of $$L_2-L_\infty $$ filtering for two kinds of network-based linear time-invariant systems. The presented method highlights two features, 'plug and play' and 'always feasible,' because it is simple and does not need to solve any complex constrained optimization problems. For measurable and unmeasurable system states, two different filter frameworks are presented, respectively. The proposed filtering strategy could guarantee the asymptotic stability of the filtering error system, while ensuring an $$L_2-L_\infty $$ performance. At the same time, the relationship between the $$L_2-L_\infty $$ disturbance attenuation level bound $$\gamma $$ and the maximum time-delay upper limit $$\tau _\mathrm{m}$$ is given. Finally, three illustrative examples are given to demonstrate the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]