Kejian Ding

A highly stable electrochemiluminescent (ECL) sensor based on graphitic carbon nitride (GCN)/Pb ²⁺ /polypyrrole (PPy) was developed to detect trace copper ions.

China's vast territory across a large latitude makes it an ideal country to investigate the mechanisms causing regional climate changes. Here, we showed that the temporal patterns in regional surface temperature are very different between low- and high latitude regions and between lightly and severely polluted regions, and that a reversal in surface temperature occurs earlier at higher-latitude regions. The latter is affected by recent drastic reductions in air pollution, which give rise to positive net radiative forcings that are the primary cause for China's regional temperature rises in the last decade. These regional climate patterns are in good agreement with both the cosmic-ray driven electron-induced reaction (CRE) theory of ozone depletion and the physics model of warming caused by halogen-containing greenhouse gases (halo-GHGs, mainly chlorofluorocarbons (CFCs)). Using the IPCC-given globally averaged radiative forcings of aerosols and ozone, our calculated results by the CFC-warming physics model showed good agreement with the observed regional surface temperature changes since 1990, giving correlation coefficients of 0.70–0.96. In lightly polluted regions, such as northeast and northwest China (Heilongjiang, Xinjiang and Inner Mongolia), Hainan and Guangdong, our calculations reproduced close observations, while underestimating temperatures in highly polluted regions such as Beijing (Hebei), Fujian, and Jiangsu. This discrepancy is explained by larger reductions in post-2013 air pollution, causing greater positive radiative forcings. Our results revealed the mechanisms for regional and global climate change.

Due to the development of social media, the mechanisms underlying consensus and chaos in opinion dynamics have become open questions and have been extensively researched in disciplines such as sociology, statistical physics, and nonlinear mathematics. In this regard, our paper establishes a general model of opinion evolution based on micro-mechanisms such as bounded confidence, out-group pressure, and in-group cohesion. Several core conclusions are derived through theorems and simulation results in the model: (1) assimilation and high reachability in social networks lead to global consensus; (2) assimilation and low reachability result in local consensus; (3) exclusion and high reachability cause chaos; and (4) a strong “cocoon room effect” can sustain the existence of local consensus. These conclusions collectively form the “ideal synchronization theory”, which also includes findings related to convergence rates, consensus bifurcation, and other exploratory conclusions. Additionally, to address questions about consensus and chaos, we develop a series of mathematical and statistical methods, including the “energy decrease method”, the “cross-d search method”, and the statistical test method for the dynamical models, contributing to a broader understanding of stochastic dynamics.

Covalent organic frameworks (COFs) with porphyrins as structural units are a new kind of porous organic polymers, which have a regular and ordered structure, abundant porosity, and good stability. In the past, the construction of porphyrin COFs was generally synthesized by routes such as a Schiff base reaction. Here, we report a new COF structure by linking the porphyrin with the triazine ring. Using a cyano group-terminated porphyrin as a structural unit precursor, a new triazine-porphyrin hyperconjugated COF (TA-Por-sp²-COF) was constructed through the cyano group's self-polymerization. The extension of porphyrin units in two directions that stemmed from the cyano group at para-positions accounts for the establishment of a highly ordered two-dimensional topological structure. Attributing to the collaboration of electron-donating and withdrawing blocks for photo-induced carrier separation and adequate porosity for mass diffusion, this hyperconjugated system showed high photocatalytic performance in organic reactions such as the aerobic coupling reaction of benzylamine and thioanisole selective oxidation.

Solar-driven interfacial evaporation is a promising technology for water recycling and purification. A sustainable solar evaporation material should have not only high photothermal conversion efficiency, but also an ecofriendly fabrication process as well as pollutant degradation and sterilization properties. We present in this work a solar evaporator based on graphitic carbon nitride (g-C₃N₄) and copper phthalocyanine (CUPC) composites with typical type-I heterojunctions. Superhydrophilic three-dimensional macroporous g-C₃N₄ was obtained by self-assembly of precursors in aqueous solution followed by thermal polycondensation. By adding various weight ratios (0.15%, 1.5% and 7.5%) of CUPC, the composites exhibited a strong absorption in the region of red and infrared light. The CUPC–CN 7.5% composite achieved a photothermal conversion efficiency of 98.5% in nanofluids with an interfacial solar evaporation efficiency of 93.6% for artificial sea water and 98.7% for deionized water, which are among the highest reported to date. Besides, the composite materials demonstrated superior water purification capabilities by decomposing dye molecules and E. coli bacteria in aqueous solution. Our work established a novel approach for the development of multifunctional interfacial evaporators based on macroporous organic semiconductor heterostructures.