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Medium- and long-chain triacylglycerol (MLCT), as a novel functional lipid, is valuable due to its special nutritional properties. Its low content in natural resources and inefficient synthesis during preparation have limited its practical applications. In this study, we developed an effective Pickering emulsion interfacial catalysis system (PE system) for the enzymatic synthesis of MLCT by trans-esterification. Lipase NS 40086 served simultaneously as a catalyst and a solid emulsifier to stabilize the Pickering emulsion. Benefitting from the sufficient oil–water interface, the obtained PE system exhibited outstanding catalytic efficiency, achieving 77.5% of MLCT content within 30 min, 26% higher than that of a water-free system. The Km value (0.259 mM) and activation energy (14.45 kJ mol−1) were 6.8-fold and 1.6-fold lower than those of the water-free system, respectively. The kinetic parameters as well as the molecular dynamics simulation and the tunnel analysis implied that the oil–water interface enhanced the binding between substrate and lipase and thus boosted catalytic efficiency. The conformational changes in the lipase were further explored by FT-IR. This method could give a novel strategy for enhancing lipase activity and the design of efficient catalytic systems to produce added-value lipids. This work will open a new methodology for the enzymatic synthesis of structured lipids. [ABSTRACT FROM AUTHOR]

Different plasticizers have obvious differences in plasticizing properties. As one of the important indicators for evaluating plasticization performance, the substitution factor (SF) has great significance for product cost accounting. In this research, a genetic algorithm with "variable mutation probability" was developed to screen the key molecular descriptors of plasticizers that are highly correlated with the SF, and a SF prediction model was established based on these filtered molecular descriptors. The results show that the improved genetic algorithm greatly improved the prediction accuracy in different regression models. The coefficient of determination (R2) for the test set and the cross-validation both reached 0.92, which is at least 0.15 higher than the R2 of the unimproved genetic algorithm. From the results of the selected descriptors, most of the descriptors focused on describing the branching of the molecule, which is consistent with the view that the branching chain plays an important role in the plasticization process. As the first study to establish the relationship between plasticizer SF and plasticizer molecular structure, this work provides a basis for subsequent plasticizer performance and evaluation system modeling. [ABSTRACT FROM AUTHOR]

Using pine pollen as a new biological template, Ce-doped TiO2 porous microspheres were prepared via the sol–gel method and impregnation method after high-temperature calcination. The samples were characterized using scanning electron microscopy, X-ray energy spectrum analysis, X-ray diffraction, UV–Vis diffuse reflectance spectroscopy, photoluminescence spectroscopy, electrochemistry, and electron spin resonance spectroscopy. Owing to the doping of cerium, the bionic material showed a better photocatalytic antibacterial performance, and the antibacterial rate against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Bacillus subtilis surpassed 99.9% within 120 min under xenon lamp irradiation. In addition, we discuss the photocatalytic sterilization mechanism of porous Ce-doped TiO2 microspheres. The antibacterial activities of this biomimetic material are mainly due to the reactive oxygen species produced by its photocatalysis; these species attack bacteria, causing them to cleave and die. Inspired by natural pollen, the materials were prepared, and they have broad application prospects for photocatalytic disinfection. [ABSTRACT FROM AUTHOR]

Bio-recycling of plastic waste is a promising solution to plastic pollution. As one of the most abundant plastic wastes, polyethylene terephthalate (PET) can be degraded by carboxylic ester hydrolases (EC 3.1.1). Nevertheless, the biological PET hydrolysis efficiency is always limited by the low activity and poor thermostability of the enzymes. Herein, to address the above barriers, we rationally mutated the relevant sites of Thermobifida cellulosilytica cutinase 1 (ThcCut1) involved in substrate binding. The wider substrate-binding pockets after mutation could facilitate the accessibility of the enzyme to the substrate. Divalent metal-binding sites were further predicted and substituted with disulfide bonds, with the aim of effectively improving the thermostability of the mutant ThcCut1. Coupled with sequence alignment and structural dynamics analysis, the ThcCut1-D205C/E254C/Q93G variant with a melting temperature exceeding the glass transition temperature of recycled PET was constructed. After comprehensively screening the active and thermally stable mutation sites, the resulting ThcCut1-G63A/F210I/D205C/E254C/Q93G (ThcCut1-AICCG) variant exhibited high enzymatic activity at a high temperature (70 °C). As result, 96.2% of the post-consumer PET bottle particles (without energy-intensive melt-quenching pretreatment) can be successfully degraded after 96 h of hydrolysis using ThcCut1-AICCG, which was 87.5 times higher than that using the wild-type ThcCut1. This novel strategy for amino acid site analysis will facilitate the modification of homologous cutinases to improve the catalytic performance, and provide a reliable technical method for constructing a PET hydrolase modification platform. [ABSTRACT FROM AUTHOR]

DMF hydrolysis is not scaring, but further condensation of HDO over strong acid sites is the intrinsic cause for loss in PX selectivity and carbon balance. [Display omitted] • Acid strength exhibits a significant influence on PX selectivity. • DMF hydrolysis to HDO is not the intrinsic cause for decrease in PX selectivity. • Condensation of HDO over strong acid sites results in loss of PX selectivity. • The process starting with HDO and ethylene for PX production is investigated. • Reducing strong acid site amount helps to improve PX selectivity. Although a precise understanding of acid strength would be essential to elucidate the reaction mechanism and boost the catalytic activity, it is still severely deficient during p -xylene (PX) production from 2,5-dimethylfuran (DMF). Herein, a series of metal phosphate catalysts featuring varied acid strength are prepared and afford an ideal platform. A combination study including kinetic analysis, converting pathway investigation and isotopic labelling experiments reveal the reversible reaction between DMF and 2,5-hexanedione (HDO) and the vital role of strong acid sites during the further conversion of HDO. DMF hydrolysis to HDO is not the intrinsic cause for decrease in PX selectivity, but further condensation of HDO over the strong acid sites is to blame. It destroys the equilibrium state of the reversible reaction and leads to loss in PX selectivity and carbon balance. Besides, the process starting with HDO and ethylene for PX production and strategies to improve PX selectivity have also been proposed. This work provides a much deeper insight into the crucial role of acid strength, which would be constructive for rational design of new catalysts and the corresponding mechanistic understanding. [ABSTRACT FROM AUTHOR]

Low temperature performance determines that the application area of biodiesel is one of the most important parameters for biodiesel. Therefore, establishing a model between biodiesel composition and low temperature performance can help manufacturers easily select or deploy raw materials. In this study, different ML methods were evaluated for the first time to establish a prediction model between biodiesel composition and CFPP. The DT-based methods has good performance in predicting CFPP of biodiesel. The stacking method was shown to have the best prediction results and stability via verification of ET, stacking and MLP methods on the test set. Importance analysis shows that palmitic acid has the greatest influence on DT-based methods. This work determind that the coefficient of determination of stacking method (R 2 >0.90) is significantly improved compared to the existing CFPP prediction model (R 2 =0.87). It provides support for the next step in a wider range of verification and promotion. [Display omitted] • Established a new model between biodiesel composition and CFPP. • Evaluated different machine learning methods for biodiesel CFPP prediction. • The stacking model has the best prediction results with the average R 2 above 0.9. • Palmitic acid content has the greatest influence on CFPP in all the factors. [ABSTRACT FROM AUTHOR]

The growing amount of plastic solid waste (PSW) is a global concern. Despite increasing efforts to reduce the residual amounts of PSW to be disposed off through segregated collection and recycling, a considerable amount of PSW is still landfilled and the extent of PSW ocean pollution has become a worldwide issue. Particularly, polyethylene (PE) and polystyrene (PS) are considered as notably recalcitrant to biodegradation due to the carbon-carbon backbone that is highly resistant to enzymatic degradation via oxidative reactions. The present research investigated the catalytic mechanism of P450 monooxygenases by quantum mechanics to determine the bio-catalytic degradation of PE or PS. The findings indicated that the oxygenase-induced free radical transition caused the carbon-carbon backbone cleavage of aliphatic compounds. This work provides a fundamental knowledge of the biodegradation process of PE or PS at the atomic level and facilitates predicting the pathway of plastics' biodegradation by microbial enzymes. [ABSTRACT FROM AUTHOR]

Recalcitrant plastic waste has caused serious global ecological problems. There is an urgent need to develop environmentally friendly and efficient methods for degrading the highly stable carbon skeleton structure of plastics. To that end, we used a quantum mechanical calculation to thoroughly investigate the oxidative scission of the carbon-carbon (C–C) backbone in polyethylene (PE). Here, we studied the reaction path of C–C bond oxidation via hydroxyl radical in PE. The flexible force constants and fuzzy bond orders of the C–C bonds were calculated in the presence of one or more carbocations in the same PE carbon chain. By comparison, the strength of the C–C bond decreased when carbocation density increased. However, the higher the density of carbocations, the higher the total energy of the molecule and the more difficult it was to be generated. The results revealed that PE oxidized to alcohol and other products, such as carboxylic acid, aldehyde and ketone, etc. Moreover, the presence of carbocations was seen to promote the cleavage of C–C backbones in the absence of oxygen. [ABSTRACT FROM AUTHOR]

• The visible-light-driven photo-reduction of Cr(VI) by formic acid was achieved. • Study on the light intensity and wavelength suggests a light-induced mechanism. • DFT simulation predicts the light-induced charge transfer process. • EPR analysis shows a stepwise pathway with Cr(V) and Cr(IV) as the intermediates. • This reaction is applicable for the treatment of Cr(VI) contaminated wastewater. To study the applicability and mechanism of the visible-light-driven photo-reduction of Cr(VI) is important since it will elucidate the chromium cycle in natural circumstances, and since this reduction reaction is important in treating wastewater contaminated by Cr(VI). Herein, we conducted an in-depth mechanism study for this process using formic acid as electron donor. The positive dependence of the Cr(VI) conversion on the incident light intensity and the good match between the apparent quantum yield (0.0039–0.39%) and the light absorption spectrum (550–365 nm) suggests a light-induced mechanism. The light-induced charge transfer occurs through the ligand-to-metal charge transfer state of the complex which forms between one dichromate molecule and two formic acid molecules through symmetrical or asymmetrical configuration as demonstrated by DFT simulation. EPR analysis further proves that this reaction occurs through a stepwise process with Cr(V) and Cr(IV) as the intermediates. The practical use of this photochemical procedure with broad electron donor scope and wide pH, reaction temperature, and initial Cr(VI) concentration ranges, is proven by the application potential evaluation. The efficient reduction of Cr(VI) by formic acid under sunlight further proves the applicability of this photochemical procedure for the treatment of Cr(VI) contaminated wastewater. Development of the present study into both the treatment of Cr(VI) contaminated wastewater, and other visible-light-driven photo-redox reactions between metals and organics are the subject of further research and results can be expected in the near future. [ABSTRACT FROM AUTHOR]

Laccases are regarded as versatile green biocatalysts, and recent scientific research has focused on improving their redox potential for broader industrial and environmental applications. The density functional theory (DFT) quantum mechanics approach, sufficiently rigorous and efficient for the calculation of electronic structures, is conducted to better comprehend the connection between the redox potential and the atomic structural feature of laccases. According to the crystal structure of wild type laccase CueO and its variant, a truncated miniature cluster model method was established in this research. On the basic of thermodynamic cycle, the overall Gibbs free energy variations before and after the one-electron reduction were calculated. It turned out that the trends of redox potentials to increase after variant predicted by the theoretical calculations correlated well with those obtained by experiments, thereby validating the feasibility of this cluster model method for simulating the redox potentials of laccases., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Jiang, Cui, Wei, Nie, Xu and Liu.)

Experimental observations for ionic hydration free energies are highly debated mainly due to the ambiguous absolute hydration free energy of proton, ΔG hyd * (H + ). Hydration free energies (HFEs) of the 112 singly charged ions in the Minnesota solvation database were predicted by six methods with explicit and implicit solvent models, namely, thermodynamic integration (TI), energy representation module (ERmod), three-dimensional reference interaction site model (3D-RISM), and continuum solvation models based on the quantum mechanical charge density (SMD) and on the Poisson-Boltzmann (PB) and generalized Born (GB) theories. Taking the solvent Galvani potential of water into account, the resulting real HFEs from TI calculations for the generalized Amber force field (GAFF) modeled ions best match the experiments based on ΔG hyd * (H + ) = -262.4 kcal/mol (Randles Trans. Faraday Soc . 1956 , 52 , 1573 - 1581 ), in agreement with our previous work on charged amino acids (Zhang et al. J. Phys. Chem. Lett. 2017 , 8 , 2705 - 2712 ). The examined computational methods show an accuracy of ∼7 kcal/mol for the GAFF-modeled ions, except for SMD with a higher accuracy of ∼4 kcal/mol. A biased deficiency in modeling anionic compounds by GAFF is observed with a larger standard deviation (SD) of 9 kcal/mol than that for cations (SD ∼ 4 kcal/mol). The relatively cheap ERmod and 3D-RISM methods reproduce TI results with good accuracy, although ERmod yields a systematic underestimation for cations by 9 kcal/mol; PB and GB generate relative (but not absolute) HFEs comparable to the TI predictions. Computational accuracy is found to be more limited by the accuracy of force fields rather than the models themselves.

Exploring the mechanism of self-assembly and guest encapsulation of nanocapsules is highly imperative for the design of sophisticated molecular containers and multistimuli-responsive functional materials. Here we present a molecular dynamics simulation protocol with implicit solvent and simulated annealing techniques to investigate the self-assembly and competitive guest (C 60 and C 70 fullerenes) encapsulation of a M 2 L 4 nanocapsule that is self-assembled by the coordination of mercury cations and bent bidentate ligands. Stepwise formation of the nanocapsule and competitive fullerene encapsulation during dynamic structural changes in the self-assembly were detected successfully. Such processes were driven by coordination bonding and π-π stacking and obey the minimum total potential energy principle. Potential of mean force calculations for guest binding to the M 2 L 4 nanocapsule explained the mechanism underlying the competitive encapsulations of C 60 and C 70 . This work helps design new functional nanomaterials capable of guest encapsulation and release.