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In this study, the competitive adsorption and migration behaviors of arsenic (As), cadmium (Cd), and chromium (Cr) in typical Chinese soils were investigated. It was observed that Hainan, Shanxi, and Zhejiang Mengjiadai soils exhibited the highest adsorption capacities for As (563 µg/g), Cd (653 µg/g), and Cr (383 µg/g), respectively. Heavy metals (HMs) adsorption capacities were predicted by Extreme gradient boosting (XGBoost) models, and the Shapley additive explanation (SHAP) was employed to elucidate the effect of soil physicochemical properties on target values. Due to redox and complexation reaction, the primary factor affecting adsorption has changed from free state manganese (Mn) in single As system to antimony (Sb) in As/Cd and As/Cr systems. Furthermore, the maximum adsorption capacity (Qm) of As increased by 49.4 % with the addition of Cd into Heilongjiang soil. Finally, the migration process of HMs in Heilongjiang, Hebei, and Hainan soils was simulated by column experiments. With a relatively large dispersion coefficient (D = 29.630 cm2/h) and small retardation factor (Rh = 0.030), Cr penetrated fastest in Heilongjiang soil. This research demonstrates that both the types and coexistence of HMs may affect the HMs behaviors in soil.

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The present study systematically investigated the elimination of benzalkonium chloride (BAC) in the zero valent iron activated persulfate (Fe0/PS) system. The influence of operational parameters, including PS concentration, Fe0 dosage and pH, were investigated through a series of kinetic experiments. When the Fe0 dosage was 5.0 mM, the initial ratio of [PS]: [BAC] was 10:1, the degradation efficiency could achieve 91.7% at pH 7.0 within 60 min. Common inorganic anions and humic acid did not significantly affect BAC degradation, implying that Fe0/PS system had a potential application prospect in the actual wastewater remediation. Based on the electron paramagnetic resonance test and quenching experiments, the BAC degradation was found to be contributed by •OH, SO4•- and Fe(IV). A total of 23 intermediates were identified by the liquid chromatography-mass spectrometry, and the degradation pathways were proposed accordingly, including dealkylation and demethylation, hydroxylation, sulfate substitution and benzyl C-N cleavage reactions. Density functional theory based calculations were conducted to realize the rationality of the proposed reaction mechanisms. The toxicity of transformation products was predicted by ECOSAR program. This work demonstrated the possibility of BAC removal in hospital and municipal wastewater by Fe0/PS treatment, and also provides a safe choice for deep treatment of quaternary ammonium salt wastewater.

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Green mold, caused by Penicillium digitatum, is the major cause of citrus postharvest decay. Currently, the application of sterol demethylation inhibitor (DMI) fungicide is one of the main control measures to prevent green mold. However, the fungicide-resistance problem in the pathogen P. digitatum is growing. The regulatory mechanism of DMI fungicide resistance in P. digitatum is poorly understood. Here, we first performed transcriptomic analysis of the P. digitatum strain Pdw03 treated with imazalil (IMZ) for 2 and 12 h. A total of 1338 genes were up-regulated and 1635 were down-regulated under IMZ treatment for 2 h compared to control while 1700 were up-regulated and 1661 down-regulated under IMZ treatment for 12 h. The expression of about half of the genes in the ergosterol biosynthesis pathway was affected during IMZ stress. Further analysis identified that 84 of 320 transcription factors (TFs) were differentially expressed at both conditions, making them potential regulators in DMI resistance. To confirm their roles, three differentially expressed TFs were selected to generate disruption mutants using the CRISPR/Cas9 technology. The results showed that two of them had no response to IMZ stress while ∆PdflbC was more sensitive compared with the wild type. However, disruption of PdflbC did not affect the ergosterol content. The defect in IMZ sensitivity of ∆PdflbC was restored by genetic complementation of the mutant with a functional copy of PdflbC. Taken together, our results offer a rich source of information to identify novel regulators in DMI resistance.

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Developing efficient and low-cost photocatalytic materials is essential for removing polychlorinated biphenyls (PCBs). In this work, the photodegradation process of fourteen representative polychlorinated biphenyls (PCBs) in both water/nitrogen-doped SiO2 (N-SiO2) and air/N-SiO2 systems was studied. The photodegradation kinetics of PCBs is consistent with the pseudo-first-order kinetic equation. The variation in the degradation effects of different PCBs in the two systems is primarily related to the position of the Cl substituent and the effective absorption wavelength range of PCBs. A total of fourteen intermediates for 4'-Dichlorobiphenyl (PCB-15), 2,2',4,4',6,6'-Hexachlorobiphenyl (PCB-155), and 2,2',3,3',4,4',5,5',6,6'-Decachlorobiphenyl (PCB-209) generated from four reaction pathways were identified based on both mass spectrometry analysis and theoretical calculations. Using the values of lnk (k denotes pseudo-first-order kinetic constants) for the 11 PCBs in the training set and the calculated molecular and structural parameters, quantitative structure-activity relationship (QSAR) models for the two systems were constructed by using multiple linear regression (MLR) method to better understand the factors affecting the photodegradation rate of PCBs. The QSAR equations were obtained with Cl atom substitution at position 3 (N3) as the main parameter, which were lnk = -1.98 - 0.19 N3 for the water/N-SiO2 system and lnk = -1.56 - 0.34 N3 for the air/N-SiO2 system, with the correlation coefficient (R2) of 0.66 and 0.73, leave-one-out cross-validation (Q2LOO) of 0.51 and 0.59, respectively, and bootstrapping validation coefficients (Q2BOOT) values of both 0.74, confirming that the models were well fitted and showed high robustness and prediction ability. This study provides valuable insights into photocatalytic degradation studies of PCBs.

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Considering that waste incineration fly ash is the main carrier of dioxins and can migrate over long distances in the atmosphere, it is of great significance to study the photochemical transformation behavior of dioxins on the surface of fly ash. In this work, 2-chlorodibenzo-p-dioxin (2-CDD) was selected to conduct a systematic photochemical study. The influence of various factors on the photodegradation of 2-CDD were first explored, and the results showed that small particle size of fly ash, low concentration of 2-CDD and appropriate level of humidity were more conducive to photodegradation, with the highest degradation percentage reaching 76%-84%. The components of fly ash (Zn (Ⅱ), Al (Ⅲ), Cu (Ⅱ) and SiO2) also had a certain promoting effect on the degradation of 2-CDD, which increases the degradation efficiency by 10%-20%, because they could act as effective photocatalysts to produce free radicals for reaction. With a higher total light exposure intensity, natural light environments led to a more complete degradation of 2-CDD than laboratory Xe lamp irradiation (90% degradation Vs. 79% degradation). Based on chemical probe and radical quenching experiment, hydroxyl radical also contributed to 2-CDD photodegradation on fly ash. A total of 16 intermediate products were detected by mass spectrometry analysis, and four initial reaction pathways of 2-CDD were speculated in the process, including dechlorination, ether bond cleavage, hydroxyl substitution, and hydroxyl addition. According to the results of density functional theory calculation, the reaction channels of ether bond cleavage and •OH attack were determined. The toxicity assessment software tool (TEST) was used to assess the toxicity and bioconcentration coefficient of reaction products, and it was found that the overall toxicity of the photodegradation products was reduced. This study would provide new insights into the environmental fate of dioxins during long-range atmospheric migration process.

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In this work, nitrogen-doped SiO2 (N-SiO2) was successfully synthesized to develop an "adsorption-photocatalytic degradation" water purification technology to remove hydrophobic organic contaminants (HOCs). As a representative of HOCs, decabromodiphenylethane (DBDPE) could be efficiently degraded under simulated sunlight after adsorption on the surface of N-SiO2. Due to the generation of reactive oxygen species (ROS) and silicon-based radicals, the photodegradation rate of DBDPE on water-SiO2 interface was 1.5-fold higher than that in water. Furthermore, the transformation pathways of DBDPE on N-SiO2 surface were compared with that in water. Bond breaking and debromination reactions were the common pathways, while hydroxylation and silicon-based substitution reactions were the specific transformation pathways for DBDPE on the surface of N-SiO2. Density functional theory (DFT) calculation was used to reveal the generation mechanism of silicon-based radicals and determine the rationality of the involvement of silicon-based radicals in DBDPE transformation. The energy barriers of silicon-based substitution reaction were comparable to that of hydroxylation and debromination reactions, which confirmed the plausibility of the generation of silicon-based substitution products. This study provides an efficient method for the disposal of HOCs, which also gives some new insights into the conversion mechanism of organic pollutants mediated by silicon-based radicals.

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Temperature sensing plays essential roles in both fundamental research and high-tech applications. In this work, three isomorphic hexanuclear lanthanide metal-organic frameworks (Ln-MOFs), Ln(BPDC-xN) (Ln = Eu3+/Tb3+, x = 0, 1, 2) were prepared based on the cluster-based synthesis strategy with three structurally similar dicarboxylate ligands 4,4'-biphenyldicarboxylic acid (H2BPDC-0N), 6-(4-carboxyphenyl)nicotinic acid (H2BPDC-1N), and [2,2'-bipyridine]-5,5'-dicarboxylic acid (H2BPDC-2N) as the organic linkers. The as-synthesized Ln-MOFs were fully characterized using single-crystal X-ray diffraction (SCXRD), powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), elemental analysis (EA), and Fourier transform infrared spectra (FT-IR). Using a Eu3+/Tb3+ co-doping approach, Eu0.001Tb0.999(BPDC-xN) (x = 0, 1, 2) were identified as potential ratiometric luminescence thermometers. Since there are two suitable distances between the energy donors and acceptors within the framework for efficient energy transfer, all Eu0.001Tb0.999(BPDC-xN) (x = 0, 1, 2) maintain high relative sensitivity over a wide temperature range from 50 K to 300 K.

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Iron-based metal-organic frameworks (MOFs) have been reported to have great potential for encapsulating doxorubicin hydrochloride (DOX), which is a frequently used anthracycline anticancer drug. However, developing a facile approach to realize high loading capacity and efficiency as well as controlled release of DOX in MOFs remains a huge challenge. Herein, we synthesized water-stable MIL-101(Fe)-C4H4 through a microwave-assisted method. It was found the nano-MOFs acted as nanosponges when soaked in a DOX alkaline aqueous solution with a loading capacity experimentally up to 24.5 wt %, while maintaininga loading efficiency as high as 98%. The mechanism of the interaction between DOX and nanoMOFs was investigated by absorption spectra and density functional theory (DFT) calculations, which revealed that the deprotonated DOX was electrostatically adsorbed to the unsaturated Fe3OCl(COO)6·H2O (named Fe3 trimers). In addition, the as-designed poly(ethylene glycol-co-propylene glycol) (F127) modified nanoparticles (F127-DOX-MIL) could be decomposed under the stimulation of glutathione (GSH) and ATP. As a result, DOX and Fe(III) ions were released, and they could undergo a Fenton-like reaction with the endogenous H2O2 to generate the highly toxic hydroxyl radical (·OH). The in vitro experiments indicated that F127-DOX-MIL could cause remarkable Hela cells inhibition through chemotherapy and chemodynamic therapy. Our study provides a new strategy to design a GSH/ATP-responsive drug-delivery nanosystem for chemo/chemodynamic therapy.

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A series of isostructural Ln-MOFs, namely Eu(BPDC-xN)(x = 0, 1, 2), with different numbers of nitrogen atoms were designed and synthesized. Due to the strong affinity between the bare phosphate group of NADPH and nitrogen functional sites, the highly selective and sensitive detection of NADPH was realized. Furthermore, as the number of sites was increased, the sensitivity significantly increased, with a detection limit as low as 0.43 µM.

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Bi can exist in a variety of chemical states (with varying ionic charges) and the microstructure of the glass surrounding the ions can be engineered to manipulate the chemical state. In this work, efficient enhancement of Ho3+ emission is observed with the change in local glass environment around Bi by adding Al2O3 to multi-component germanosilicate glass. In this multi-component glass, Al3+ can form tetrahedral AlO4 by accepting the non-bridging oxygen (NBO) and then, the addition of the AlO4-tetrahedron to the glass network facilitates the diffusion of alkali metals. Hence, Al2O3 decreases the Ba2+-rich domain and is conducive to the existence of Bi ions that are at low valence state. Moreover, the emission spectra indicate high efficiency energy transfer (ET) derived from NIR emission centers (Bi0/Bi+) located in close proximity to the Ho3+ ions. These results indicate that the optimized fluorescence of Ho3+ for optical fiber laser can be achieved by adjusting the local structure of the host glass.

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Higher concentrations of rare earth (RE) ions in glass materials would be favorable for the output of single-frequency fiber lasers. In this Letter, we adjusted the topological structure of glass networks through controlling the numbers of non-bridging oxygens (NBOs) and bridging oxygens (BOs) by tuning the composition of the glasses, hence increasing the RE doping concentration of germanosilicate glasses. The increased flexibility of the glass networks favors the distribution of clusters of RE ions to decrease fluorescence quenching, which was validated by both our experimental and theoretical results. To the best of our knowledge, for the first time, a highly Er3+-doped (up to 7 mol. %) heavy metal oxide glass was fabricated without quenching by tuning the components of the glass. In addition, we have demonstrated an approach to enhance the fluorescence properties of heavily RE-doped glass materials by tailoring network topology.