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Enzymatic browning is a major industrial problem of fresh-cut vegetables and fruits. Bioactive peptides are safe, nutritive and low-cost sources of antioxidant and antimicrobial agents. However, there has been little research on the effect of random peptides on anti-browning of fresh-cut food. For developing more natural and nutritive anti-browning agents, the effect of the enzymatic hydrolysis of random peptides from cod fish skin on polyphenol oxidase (PPO), peroxidase (POD), phenylalanine ammonia-lyase (PAL), total phenolic content, membrane permeability, malondialdehyde (MDA) content and color changes were investigated during fresh-cut potato storage. The results showed that 0.1% (w/w) cod peptides efficiently blocked enzymatic browning by inhibiting PPO, POD and PAL activities, reducing the total phenol accumulation during the entire 8 d storage at 4 °C. Furthermore, the membrane permeability and MDA content increases were delayed in 0.1% cod peptides treatment compared with the control. Oddly, the browning of fresh-cut potato was aggravated in 1.0% cod peptides treatment, which expressed higher POD and PAL activities. Meanwhile, the functional composition of cod peptides was a random component, which total 1765 peptides were identified by LC–MS/MS and the amino acids length of peptides were 4∼57 in the cod peptides. All the results showed that random peptides might be promising candidates as anti-browning agents for fresh-cut potato slices.

Fault diagnosis and controller design are two important aspects to improve proton exchange membrane fuel cell (PEMFC) system durability. However, the two tasks are often separately performed. For example, many pressure and voltage controllers have been successfully built. However, these controllers are designed based on the normal operation of PEMFC. When PEMFC faces problems such as flooding or membrane drying, a controller with a specific design must be used. This paper proposes a unique scheme that simultaneously performs fault diagnosis and tolerance control for the PEMFC system. The proposed control strategy consists of a fault diagnosis, a reconfiguration mechanism and adjustable controllers. Using a back-propagation neural network, a model-based fault detection method is employed to detect the PEMFC current fault type (flooding, membrane drying or normal). According to the diagnosis results, the reconfiguration mechanism determines which backup controllers to be selected. Three nonlinear controllers based on feedback linearization approaches are respectively built to adjust the voltage and pressure difference in the case of normal, membrane drying and flooding conditions. The simulation results illustrate that the proposed fault tolerance control strategy can track the voltage and keep the pressure difference at desired levels in faulty conditions.

Two-dimensional (2D) nanomaterials have attracted much interest as promising candidates for next generation energy storage, electronics and catalytic applications, due to their unique topology and electronic structure. However, the development of an operable and versatile solution processing technique for simple fabrication of high-quality 2D nanosheets continues to present a significant challenge. Here, an ultrathin indium sulfide nanosheet is synthesized via a simple solution-phase reaction involving two steps: i) thermal decomposition of precursors to form a crystal nucleus; ii) growth of 2D nanosheets in a mixture of amino ligand and alkane solvent. The alkane, matching the amino ligand structure in terms of geometry, could assemble with the ligand to form a soft template and thus induce a 2D arrangement of the nucleus. Moreover, the chemical inertness of the alkane facilitated rotation of crystal seeds, resulting in anisotropic growth of the nanosheet. We further demonstrated that the geometrically matched alkane-assisted solution processing reaction could be applied to synthesize various 2D metal chalcogenides. Functionally, the acquired indium sulfide nanosheets, which possess high photoelectric activity, were introduced for fabrication of photoelectrodes capable of efficient photoelectrochemical water splitting. Our work opens up a new perspective toward the construction and potential applications for various 2D nanomaterials.

We utilized femtosecond time-resolved coherent anti-Stokes Raman spectroscopy (CARS) to study the ultrafast vibrational dynamics in distilled water at room temperature. The CARS signals from the broad OH-stretching modes between 3100 cm−1 and 3700 cm−1 were obtained and analyzed. The dephasing times of four Raman modes in water were detected and compared.

Spectrally dispersed femtosecond time-resolved coherent anti-Stokes Raman spectroscopy is utilized to study the ultrafast vibrational dynamics in rhodamine B dye in solution at room temperature. The anti-Stokes intensities are monitored as a function of time and wavenumber. By simply changing the timing of laser pulses, the vibrational dynamics of excited Raman transitions in rhodamine B molecules can be tracked and detected.