Bimetal doped Cu–Fe-zeolitic imidazole framework-8 (ZIF-8)/graphitic carbon nitride (GCN) (Cu–Fe-ZIF-8/GCN) nanocomposites were prepared via one-pot and ion-exchange methods. The main influencing factors, such as adsorbent concentration, TC concentration, initial pH, and coexisting ions, were evaluated in detail. Due to the suitable pore structures and the presence of multiple interactions on the surface, the nanocomposite showed a high adsorption capacity up to 932 mg g⁻¹ for tetracycline hydrochloride (TC), outperforming ZIF-8 by 4.8 times. The adsorption kinetics and adsorption isotherm were depicted in good detail using pseudo-second-order kinetic and Langmuir models, respectively. Thermodynamic calculation revealed that the adsorption of the nanocomposite under experimental conditions was a spontaneous heat absorption process, and was primarily driven by chemisorption. After four cycles of use, the nanocomposite retained 87.2% of its initial adsorption capacity, confirming its high reusability and broad application prospects in removing tetracycline-type pollutants from wastewater.

Coal spontaneous combustion (CSC) is a disaster that seriously threatens safe production in coal mines. Revealing the mechanism of CSC can provide a theoretical basis for its prevention and control. Compared with experimental research is limited by the complexity of coal molecular structure, the quantum chemical calculation method can simplify the complex molecular structure and realize the exploration of the mechanism of CSC from the micro level. In this study, toluene and phenylacetaldehyde were used as model compounds, and the quantum chemical calculation method was adopted. The reaction processes of the methyl and aldehyde groups with oxygen were investigated with the aid of the Gaussian 09 software, using the B3LYP functional and the 6-311 + G(d,p) basis set and including the D3 dispersion correction. On this basis, the generation mechanisms of CO and CO₂, two important indicator gases in the process of CSC, were explored. The calculation results show that the Gibbs free energy changes and enthalpy changes in the two reaction systems are both of negative values. Accordingly, it is judged that the reactions belong to spontaneous exothermic reactions. In the reaction processes, the activation energy of CO is less than that of CO₂, indicating that CO is formed more easily in the above-two reaction processes. In addition, the variations in concentrations of important oxidation products (CO and CO₂) and main active functional groups (such as methyl, carboxyl and carbonyl) with temperature were revealed through a low-temperature oxidation experiment. The experimental results verify the accuracy of the above quantum chemical reaction path. Moreover, it is also found that the generation mechanisms of CO and CO₂ in coal samples with different metamorphic degrees are different. To be specific, for low-rank coal (HYH), CO and CO₂ mainly come from the oxidation of alkyl side chains; for high-rank coal (CQ), CO is produced by the oxidation of alkyl side chains, and CO₂ is attributed to the inherent oxygen-containing structure.

Holliday junctions (HJs) are key DNA intermediates in genetic recombination and are eliminated by nuclease, termed resolvase, to ensure genome stability. HJ resolvases have been identified across all kingdoms of life, members of which exhibit sequence-dependent HJ resolution. However, the molecular basis of sequence selectivity remains largely unknown. Here, we present the chloroplast resolvase MOC1, which cleaves HJ in a cytosine-dependent manner. We determine the crystal structure of MOC1 with and without HJs. MOC1 exhibits an RNase H fold, belonging to the retroviral integrase family. MOC1 functions as a dimer, and the HJ is embedded into the basic cleft of the dimeric enzyme. We characterize a base recognition loop (BR loop) that protrudes into and opens the junction. Residues from the BR loop intercalate into the bases, disrupt the C-G base pairing at the crossover and recognize the cytosine, providing the molecular basis for sequence-dependent HJ resolution by a resolvase.

In this study, walnut shell (WS) was used as feedstock, incorporating lithium carbonate (LC), sodium carbonate (SC), potassium carbonate (PC), and potassium hydroxide (PH) as pyrolysis catalysts and carbonization activators. A one-step method that allows catalytic pyrolysis and carbonization to be carried out consecutively under their respective optimal conditions is employed, enabling the concurrent production of high-quality pyrolysis oil, pyrolysis gas, and carbon materials from biomass conversion. The effects of LC, SC, PC, and PH on the yield and properties of products derived from WS pyrolysis as well as on the properties and performance of the resulting carbon materials were examined. The results indicated that the addition of LC, SC, PC, and PH enhanced the secondary cracking of tar, leading to increased solid and gas yields from WS. Additionally, it increased the production of phenolic compounds in bio-oil and H₂ in syngas, concurrently yielding a walnut shell-based carbon material exhibiting excellent electrochemical performance. Specifically, when PC was used as an additive, the phenolic content in the pyrolysis oil increased by 27.64% compared to that without PC, reaching 74.9%, but the content of ketones, acids, aldehydes, and amines decreased. The hydrogen content increased from 2.5% (without the addition of PC) to 12.75%. The resulting carbon (WSC–PC) displayed a specific surface area of 598.6 m² g⁻¹ and achieved a specific capacitance of 245.18 F g⁻¹ at a current density of 0.5 A g⁻¹. Even after 5000 charge and discharge cycles at a current density of 2 A g⁻¹, the capacitance retention rate remained at 98.16%. This method effectively enhances the quality of the biomass pyrolysis oil, gas, and char, contributing to the efficient and clean utilization of biomass in industrial applications.

In this study, variations in the free radical concentration, degree of swelling (Q), and extraction yield of Buertai coal (C%, 80.4%) in 11 solvents with different characteristics were determined to investigate the interaction between the coal and solvent, as well as the bond cleavage during solvent extraction. Derivative thermogravimetry (DTG) results for the residues and raw coal were compared to confirm whether the covalent bond breaks during solvent extraction. The free radical concentration decreases in certain solvents but increases in a few others. The relative free radical concentration, Q, and extraction yield are positively correlated. The charge-transfer capability of the solvent, and in particular its electron-donating capability, plays an essential role in influencing the interaction between the coal and solvent. The increase in the free radical concentration during solvent extraction can be attributed to (1) the formation or decomposition of charge-transfer complexes, (2) dissociation of charge-transfer complexes into radical ions, and (3) breakage of weak covalent bonds. DTG results show the occurrence of weak covalent bonds breakage at temperatures of 133.9–320.1 °C during solvent extraction due to the reduction of the bond energy caused by the formation of radical ions.