Search

Recently, researchers are no longer satisfied with the investigation of the fluorescence properties of carbon dots (CDs), but instead focus on the more attractive afterglow luminescence, especially room temperature phosphorescence (RTP) and thermal activation delayed fluorescence (TADF). Numerous attempts have been made to construct CD-based afterglow materials, including embed CDs in various rigid matrices or construct self-protective structures. Because of the diversity of construction methodologies, different mechanisms and effects would be produced, thus resulting in distinguishing afterglow characteristics. Afterglow of CDs in organic matrices is mainly due to the formation of hydrogen bonds, which can suppress intramolecular vibration and stabilize triplet states, thus generating afterglow emission. Afterglow of CDs in diverse inorganic matrices are completely different because the multifarious interactions between CDs and different matrices are generated (e.g., rigid structure covalent bonds, structural confinement, energy transform, etc). The self-protective CDs always possess polymer-like structure or polymer-chains on their surface, which can act as rigid matrix to activating afterglow emission. This review aims to sum up the relationships between structure construction and afterglow characteristics, and the mechanism of afterglow generation, which are of great significance for stimulating more exciting progress in the purposeful design of afterglow materials.

Biomimetic nanodevice is an important branch to expand the potential applications of artificial nanochannels. Here, we constructed nanochannels for cascade response of borate and cis-hydroxyl compounds by modifying the nanochannels of track-etched polycarbonate (TEPC) membranes with polyvinyl alcohol (PVA). Firstly, borate bound to PVA and increased the negative charge density on the surface of the nanochannels, which obstructed the transport of 1,5-naphthalene disulfonate (NDS2−). Subsequently, the addition of cis-hydroxyl compounds induced leaving of borate due to the stronger binding affinities between borate and cis-hydroxyl compounds, which reduced the negative charge density on nanochannels and then enhanced the transport of NDS2−. The cascade response of the nanochannels also accord with the properties of IMP (implication) logic gate. In addition, such nanochannels showed good reproducibility and reversibility. Therefore, this cascade response model based on nanochannels has the potential to be used as switches in area of actuators and biosensors, and is also expected to be used to understand the interaction of substances in nanoscale and simulate the physiological functions of boron.

The outbreak of the COVID-19 pandemic in 2020 has posed unprecedented challenges for fish trade worldwide. This study examines these challenges through an observation of China’s fish import and export activities and a qualitative study on evolving policies in the first nine months of 2020. The results indicate that control measures responding to uncertainty regarding the source of the disease and transmission path, the pressing need for restriction of the movement of people and goods, and fear of a second wave of outbreaks have substantially disrupted fish trade. To meet these challenges, certain coping measures are adopted to offset negative effects in the short term. These measures indicate the government’s pivotal role in stabilizing the supply chain and striking a balance between control requirements and efficiency required in trading activities, as well as the importance to find alternative markets to mitigate risks brought by the delayed supply and the plummeting consumption market. It concludes with some suggestions on improving international cooperation and domestic regulation for building resilience in long run.