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Although nanotechnology has offered effective and efficient solutions for environmental remediation, the full utilization of sustainable energy and the avoidance of secondary pollution are still challenges. Herein, we report a two-step modification strategy for TiO2 nanoparticles by first forming a thin, surface-adherent polydopamine (PDA) shell onto the nanoparticles and then assembling core-shell nanoparticles as a photodegradation coating. The composite coating modified from TiO2 could not only realize the highly efficient utilization of photons from the visible region but also avoid the secondary pollution of nanoparticles during application. Additionally, improvements in the adsorption ability after modification greatly facilitated the photocatalytic process of the modified materials. A preliminary in vivo study on Daphnia magna and a wastewater treatment experiment suggest that treatment with the composite coating can effectively eliminate fluorene and significantly reduce its lethality. We believe the two-step modification scheme can open new avenues for the facile modification of nanomaterials for designed purposes, especially in the field of environmental remediation. [ABSTRACT FROM AUTHOR]

The controllable growth of the cavity is the basis by which underground coal gasification (UCG) can achieve stable production, and the oxygen flow path and velocity are important factors in determining the expansion rate of the cavity. In this paper, a mathematical model of UCG in horizontal channels was developed, and the effects of multiple factors, including temperature, pressure, flow velocity, and the size of the cavity, on the flow pattern, path, and velocity field distribution of oxygen in the cavity were investigated by using COMSOL Multiphysics software. The results showed that temperature and pressure were the influencing factors of thermal buoyancy. In the established model, oxygen formed a counter-clockwise air vortex at the gas injection port under normal pressure, and the range of the air vortex and the gas flow rate increased with the increase in temperature. In the high-temperature area located in the center of the cavity, the phenomenon of oxygen throttling occurred, and the oxygen flow velocity increased. When the maximum temperature in the cavity was over 850 °C, gas back-mixing occurred at the end of the cavity. Under pressurized conditions, the air vortex at the inlet and back-mixing phenomenon at the outlet disappeared. The flow velocity and the cross-sectional area of the cavity determined the thermal resistance. In the model, the flow velocity was between 0.045 and 0.40 m/s and there were both airflow vortices and back-mixing. In addition, with the expansion of the cavity, back-mixing progressively decreased at the outlet and the airflow vortex changed from counter-clockwise to clockwise., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)

In this study, a biocompatible solid-phase microextraction (SPME) fiber with high-coverage capture capacity based on a nitrogen-rich porous polyaminal was developed. The fiber was used to track the bioaccumulation and elimination of carbamates (isoprocarb, carbofuran, and carbaryl) and their metabolites ( o -cumenol, carbofuran phenol, and 1-naphthalenol) in living Chinese cabbage plants ( Brassica campestris L. ssp. chinensis Makino (var. communis Tsen et Lee)). A case-and-control model was applied in the hydroponically cultured plants, with the exposed plant groups contaminated under three carbamates at 5 μg mL -1 . Both bio-enrichment and elimination of carbamates and their metabolites in living plants appeared to be very fast with half-lives at ∼0.39-0.79 and ∼0.56-0.69 days, respectively. Statistical differences in the endogenous plant metabolome occurred on day 3 of carbamate exposure. In the exposed group, the plant metabolic alterations were not reversed after 5 days of contaminant-free growth, although most contaminates had been eliminated. Compared with prior nutriological and toxicological studies, >50 compounds were first identified as endogenous metabolites in cabbage plants. The contents of the glucosinolate-related metabolites demonstrated significant time-dependent dysregulations that the fold changes of these key metabolites decreased from 0.78-1.07 to 0.28-0.82 during carbamate exposure. To summarize, in vivo SPME provided new and important information regarding exogenous carbamate contamination and related metabolic dysregulation in plants.

Combined with the advantages of microwave pyrolysis and catalytic pyrolysis, the microwave pyrolysis experiment of low-rank coal under the synergism of catalyst was carried out. The dielectric response of coal samples and metal compound catalysts to microwave was analyzed quantitatively. The microwave pyrolysis behavior and product distribution of low-rank coal were studied. The effects of microwave heating and catalyst properties on the properties of pyrolysis products were analyzed in depth. Results show that the heating effect of dielectric loss and ionic conduction loss of metal compound catalysts could further promote the rapid temperature rise of coal samples. The catalysts could effectively improve the product distribution and properties in the process of microwave pyrolysis of low-rank coal. Compared with the control group, the output of syngas (H 2 + CO) increases by a maximum of 1.72 times, and the content of asphaltene in tar reduces by a maximum of 0.66 times. The introduction of K 2 CO 3 and CaCl 2 is conducive to the formation of a more developed pore structure and the increase of the specific surface area of semicoke. The co-action of the developed pore structure of semicoke and properties of residual catalysts could significantly improve the CO 2 gasification activity of semicoke., Competing Interests: The authors declare no competing financial interest., (Copyright © 2020 American Chemical Society.)

Nanostructured materials have great potential for solid phase microextraction (SPME) on account of their tiny size, distinct architectures and superior physical and chemical properties. Herein, a core-shell TiO 2 @C fiber for SPME was successfully fabricated by the simple hydrothermal reaction of a titanium wire and subsequent amorphous carbon coating. The readily hydrothermal procedure afforded in situ synthesis of TiO 2 nanowires on a titanium wire and provided a desirable substrate for further coating of amorphous carbon. Benefiting from the much larger surface area of subsequent TiO 2 and good adsorption property of the amorphous carbon coating, the core-shell TiO 2 @C fiber was utilized for the SPME device for the first time and proved to have better performance in extraction of polycyclic aromatic hydrocarbons. In comparison to the polydimethylsiloxane (PDMS) and PDMS/divinylbenzene (DVB) fiber for commercial use, the TiO 2 @C fiber obtained gas chromatography responses 3-8 times higher than those obtained by the commercial 100 μm PDMS and 1-9 times higher than those obtained by the 65 μm PDMS/DVB fiber. Under the optimized extraction conditions, the low detection limits were obtained in the range of 0.4-7.1 ng L -1 with wider linearity in the range of 10-2000 ng L -1 . Moreover, the fiber was successfully used for the determination of polycyclic aromatic hydrocarbons in Pearl River water, which demonstrated the applicability of the core-shell TiO 2 @C fiber.

A novel solid-phase microextraction (SPME) fiber was prepared by gluing poly(diallyldimethylammonium chloride) (PDDA) assembled graphene oxide (GO)-coated C18 composite particles (C18@GO@PDDA) onto a quartz fiber with polyaniline (PANI). The fiber surface coating was sequentially modified with bioinspired polynorepinephrine, which provided a smooth biointerface and makes the coating suitable for in vivo sampling. The novel custom-made coating was used to extract acidic pharmaceuticals, and high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) was employed for analysis. The custom-made coating exhibited a much higher extraction efficiency than the previously used commercial polydimethylsiloxane (PDMS) and polyacrylate (PA) coatings. The custom-made coating also possessed satisfactory stability (the relative standard deviations (RSDs) ranged from 1.60% to 10.3% for six sampling-desorption cycles), interfiber reproducibility (the RSDs ranged from 2.61% to 11.5%), and resistance to matrix effects. The custom-made fibers were used to monitor the presence of acid pharmaceuticals in dorsal-epaxial muscle of living fish, and satisfactory sensitivities (limits of detection ranged from 0.13 ng/g to 7.56 ng/g) were achieved. The accuracies were verified by the comparison with liquid extraction. Moreover, the novel fibers were successfully used to monitor the presence of acidic pharmaceuticals in living fish, which demonstrated that the custom-made fibers were feasible for possible long-term in vivo continuous pharmaceutical monitoring.