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The survival of the tourism industry is closely linked to the environment, but the rapid development of the tourism industry has led to greater pressure on the ecological environment. China's tourism development has been under the influence of government-led strategy and it is more closely connected with the government and has a greater impact on the environmental investment decisions of tourism enterprises. Based on rent-seeking theories and externality theories, tourism-related listed companies in China are selected as empirical research samples to study the relationship between political connection and environmental protection investment of tourism-related listed companies. The results show that the degree of political connection of listed companies involved in tourism has a significant negative influence on environmental protection investment. This study enriches the related contents of political connection and environmental protection investment in theory, and also provides practical significance in the environmental protection investment of tourism-related listed companies. [ABSTRACT FROM AUTHOR]

Epithelial ovarian cancer (EOC) is the most common and fatal subtype of ovarian malignancies, with no effective therapeutics available. Our previous studies have demonstrated extraordinary suppressive efficacy of enterolactone (ENL) on EOC. A chemotherapeutic agent, trabectedin (Trabe), is shown to be effective on ovarian cancer, especially when combined with other therapeutics, such as pegylated liposomal doxorubicin or oxaliplatin. Thrombospondin 1 (THBS1), a kind of matrix glycoprotein, plays important roles against cancer development through inhibiting angiogenesis but whether it is involved in the suppression of EOC by ENL or Trabe remains unknown. To test combined suppressive effects of ENL and Trabe on EOC and possible involvement of THBS1 in the anticancer activities of ENL and Trabe. The EOC cell line ES‐2 was transfected with overexpressed THBS1 by lentivirus vector. We employed tube formation assay to evaluate the anti‐angiogenesis activity of ENL and of its combined use with Trabe after THBS1 overexpression and established drug intervention and xenograft nude mouse cancer models to assess the in vivo effects of the hypothesized synergistic suppression between the agents and the involvement of THBS1. Mouse fecal samples were collected for 16S rDNA sequencing and microbiota analysis. We detected strong inhibitory activities of ENL and Trabe against the proliferation and migration of cancer cells and observed synergistic effects between ENL and Trabe in suppressing EOC. ENL and Trabe, given either separately or in combination, could suppress the tube formation capability of human microvascular endothelial cells, and this inhibitory effect became even stronger with THBS1 overexpression. In the ENL plus Trabe combination group, the expression of tissue inhibitor of metalloproteinases 3 and cluster of differentiation 36 was both upregulated, whereas matrix metalloproteinase 9, vascular endothelial growth factor, and cluster of differentiation 47 were all decreased. With the overexpression of THBS1, the results became even more pronounced. In animal experiments, combined use of ENL and Trabe showed superior inhibitory effects to either single agent and significantly suppressed tumor growth, and the overexpression of THBS1 further enhanced the anti‐cancer activities of the drug combination group. ENL and Trabe synergistically suppress EOC and THBS1 could remarkably facilitate the synergistic anticancer effects of ENL and Trabe. [ABSTRACT FROM AUTHOR]

Extraction and determination of trace hazardous components from complex matrices continue to attract public attention. In this work, magnetic porous carbon (MPC) was prepared for efficient magnetic solid phase extraction (MSPE) of fluoroquinolone (FQ) antibiotics in food and water samples. To prepare the MPC, an Fe-based metal–organic framework (MIL-101(Fe)) was grown on a network of graphene oxide and multi-walled carbon nanotubes through a hydrothermal method, and then a carbonization process under a nitrogen atmosphere was carried out to obtain the MPC with high specific surface area and good magnetism. Four target FQs including ciprofloxacin (CIP), enrofloxacin (ENO), lomefloxacin (LOM) and ofloxacin (OFX) were enriched using the as-prepared MPC and determined by coupled high-performance liquid chromatography. Under the optimal conditions, the established MSPE-HPLC-UV detection method exhibited a linear range of 0.5–800 μg L−1 and detection limits of 0.11–0.18 μg L−1 with relative standard deviations (RSDs) of 0.5–4.8%. When applied in the determination of the above four FQs in real samples such as lake water, milk and pork, good recoveries between 85.2 and 103.7% were obtained, and the RSDs were less than 4.8%. This work indicates that the MPC material can be a good adsorption material and has good application prospects in antibiotics enrichment and/or removal from complex samples. [ABSTRACT FROM AUTHOR]

Herein, we explore a general Cu2−xS nanocube template‐assisted and reverse cation exchange‐mediated growth strategy for fabricating hollow multinary metal sulfide. Unlike the traditional cation exchange method controlled by the metal sulfide constant, the introduction of tri‐n‐butylphosphine (TBP) can reverse cation exchange to give a series of hollow metal sulfides. A variety of hollow multinary metal sulfide cubic nanostructures has been demonstrated while preserving anisotropic shapes to the as‐synthesized templates, including binary compounds (CdS, ZnS, Ag2S, PbS, SnS), ternary compound (CuInS2, ZnxCd1−xS), and quaternary compound (single‐atom platinum anchored ZnxCd1−xS; ZnxCd1−xS‐Pt1). Experimental and density functional theory (DFT) calculations show that the hollow metal sulfide semiconductors obtained could significantly improve the separation and migration of photogenerated electron‐hole pairs. Owing to the efficient charge transfer, the ZnxCd1−xS‐Pt1 exhibited outstanding photocatalytic performance of CO2 to CO, with the highest CO generation rate of 75.31 μmol h−1. [ABSTRACT FROM AUTHOR]

Herein a rapid and sensitive fluorometric bioanalysis platform for mercury(II) (Hg2+) detection was innovatively developed using ultrathin two-dimensional MXenes (Ti3C2) as fluorescence quencher and Hg2+-induced exonuclease III (Exo III)-assisted target recycling strategy for efficient signal amplification. Initially, fluorophore-labeled single-stranded DNA (FAM-labeled probe) can be easily adsorbed onto the surface of ultrathin Ti3C2 nanosheets by hydrogen bonding and metal chelating interaction, and the fluorescence signal emitted by the FAM-labeled probe is quenched strongly owing to the fluorescence resonance energy transfer between the FAM and ultrathin Ti3C2 nanosheets. Upon sensing the target Hg2+, the protruding DNA fragment at the 3′ end of hairpin will hybridize with primer (hairpin-Hg2+-primer), and then further digested by Exo III to produce a probe (nicker). The released target Hg2+ and primer continue to participate in the next recycling, resulting in more hairpin probes becoming nickers. The combination of a large number of nickers and FAM-probe resulted in a significant increase in the fluorescence signal of the system, which was attributed to the fact that the double helix DNA was more rigid and separated from the surface of the ultrathin Ti3C2 nanosheets. The obvious fluorescence signal change of the Ti3C2-based Exo III-assisted target recycling can be accurately monitored by fluorescence spectrometry, which is also proportional to the concentration of Hg2+. Under optimum operating conditions, the peak intensity (520 nm wavelength) of fluorescence increased with increasing Hg2+ within a wide dynamic working range from 0.05 nM to 50 nM (R2 = 0.9913) with a limit of detection down to 42.5 pM. The proposed strategy uses ultrathin MXenes as a platform for binding nucleic acids, which contributes to its potential in nucleic acid hybridization-based biosensing and/or nucleic acid signal amplification bio-applications. [ABSTRACT FROM AUTHOR]