摘要 : Purpose This study examined the influence of corporate governance (CG) in relation to venture capital (VC) investment on invested firm's corporate social responsibility (CSR) performance in the Chinese context. More specifically, this paper examined the mediation of the proportion of independent directors (INDD), management shareholding (MSH) and executives' political connections (POLC) in the above-mentioned relationship. Design/methodology/approach This empirical study performed multiple mediation testing and bootstrap mediation robustness test on data from Chinese A-class shares IPO companies between 2010 and 2018. Findings The results of direct relationship analysis showed that VC support is detrimental to firm' CSR performance, consistent with previous research studies. The indirect effect analysis showed that VC reduced firm' CSR through reduction of INDD on board and increased MSH. Conversely, VC contributed to firm's CSR through higher POLC, which confirmed the significance of the joint mediation model. Practical implications This study offers stakeholders the opportunity to develop a deeper understanding of the role of VC institutions, independent directors and executives, in terms of firm's CSR, as well as provides insights on control rights allocation and policy drafting on independent directors when considering accessing VC support. Originality/value By analyzing the mediation model of the VC–CSR relationship, this paper provides evidence to enrich the debate on the role of CG in the relation between VC and firm's CSR.

摘要 : Non-radical catalytic oxidation processes can eliminate refractory pollutants from wastewater containing complex substrates such as dissolved organic matter, but the production of selective non-radicals is challenging during the activation of peroxymonosulfate (PMS). Herein, a novel magnetic carbon-based catalyst (Fe 3 O 4 @CD-8, where 8 represents an annealing temperature of 800 °C) with N and Fe species as catalytic active sites was fabricated to remediate sulfamethoxazole (SMX)-containing water. It showed excellent SMX removal efficiency and facilitated singlet oxygen ( 1 O 2 ) production. The characterization results revealed that Fe 3 O 4 @CD-8 had a microscopically hierarchical pore structure and an overall core–shell-like structure. Due to its large specific surface area, N-containing species, and Fe nanoparticles, 0.1 g/L Fe 3 O 4 @CD-8 removed almost 100% SMX (24 min) and achieved a 44.1% mineralization (40 min) efficiency in the presence of 0.5 mM PMS. This catalytic system also maintained its removal performance in the presence of inorganic anions and humic acids and over a wide pH range of 3–11, showing good tolerance to various environmental factors. 1 O 2 was confirmed to be the predominant active species for SMX degradation using the Fe 3 O 4 @CD-8/PMS system. Density functional theory (DFT) calculations, intermediate monitoring, and toxicity evaluation demonstrated that SMX was transformed into low-toxicity molecules and completely mineralized into CO 2 and H 2 O. The addition of Fe nanoparticles enhanced PMS adsorption and facilitated the Fe(III)/Fe(II) redox cycle to accelerate the activation of PMS. This study provides new insights and strategies for the controlled production of non-radicals for remediating antibiotic-containing wastewater.

摘要 : Three-dimensional sponge-architecture covalent organic frameworks (COFs)-aerogel was successfully designed and synthesized via a freeze-drying template approach, and utilized as an efficient sorbent in solid-phase extraction (SPE). A method for selective enrichment of pharmaceutical contaminants including tetracycline, chlortetracycline, methacycline and oxytetracycline in the environment and food samples was proposed by combining with high performance liquid chromatography (HPLC). To understand the adsorption mechanism, selectivity test and molecular dynamics (MD) simulated calculation were both carried out. The experimental and in-silico results demonstrated that the COFs-aerogel possessed high selectivity for contaminants with H bond acceptors/donors and good efficiency with maximum adsorption capacity up to 294.1 mg/g. The SPE-based HPLC method worked well in the range of 8–1000 ng/mL, with the need of little dose of adsorbent and sample volume while no need of spectrometer, outgoing the reported adsorbents. Under the optimized conditions, the intra-day and inter-day relative standard deviations (RSD) of repeatability were within 2.78–6.29 % and 2.44–8.42 % (n = 5). The results meet the current detection requirement for practical applications, and could be extended for further design of promising adsorbents.

摘要 : G-quadruplexes (G4) have received significant attention in the field of aptasensors owing to their unique physicochemical characteristics. A dual-mode, protein-free and label-free aptamer sensor based on plasmonic colorimetry and G4 fluorescence (PC@GF-aptasensor) was proposed for ochratoxin A (OTA). Colorimetry mode was achieved through the surface plasmon resonance (SPR) effect, which related to the OTA-Apt-based G4–OTA. The fluorescence mode was reflected by the insertion of thioflavin T (ThT) into G4–OTA. The OTA could be interpreted via three readouts: (1) naked eye (LOD of 2.0 ng mL −1 ), (2) smartphone (LOD of 1.65 ng mL −1 ), and (3) spectrofluorometer (LOD of 0.93 ng mL −1 ). The PC@GF-aptasensor exhibited several advantages, such as a standardised recognition group, simplified operation, low background signal, and practicality. The proposed PC@GF-aptasensor integrated SPR-based multicolour interpretation and ThT-inserted fluorescence reflection to obtain a dual-mode optical biosensor, which may provide valuable insights for the development of other targets with G4-based aptamers.

摘要 : The DCMD technology for wastewater treatment is very promising. However, it is easily suffered by membrane fouling and wetting. In this study, a Janus membrane was fabricated by coating polyvinylamine (PVAM) and gallic acid (GA) onto one side of a PVDF composite membrane, which another side is covered with POTS-SiO 2 . The PVAM and GA side could bind water to form a hydration layer, thus repel the contaminants. The POTS-SiO 2 side was superhydrophobicity and prevented the membrane wetting. Finally, The Janus membrane presented exceptional performance in separating salt containing emulsified oil by DCMD. It kept a stable flux of 17.0 ± 0.2 Kg·m −2 ·h −1 and a low level conductivity of 0.60 ± 0.02 μS/cm in the cold side during the 36 h DCMD procedure, compared with the pristine PVDF membrane and the PVDF/POTS-SiO 2 membrane. The results presented simultaneously antifouling and antiwetting properties of the Janus membrane. While the Janus membrane can be well used in desalination of emulsified oil containing salt, it has a great potential for application to treat other complex wastewater.

摘要 : High-performance porous polyimide (PI) monoliths, including PI aerogels, sponges, and foams, have become one of the hotspots in both researching and applications due to their superior properties such as high porosity, outstanding mechanical and thermal stability, low dielectric constant and thermal conductivity. Up to now, various fabricating methods and applicating situations for PI porous monolith materials have been reported. From the viewpoint of molecular chemistry, porous structure construction, as well as the functional modification, the property optimization and adjustment are feasible, endowing PI monoliths with promising potential for different practical applications ( e.g. sensors, low-k materials, thermal management, energy field and utilization, absorption and filtration, photonic utilization, etc.). In this review, the recent progress of porous PI monoliths was summarized in detail based on the fabrication methods, functional modifications, as well as multi-functional applications. Besides, the future perspectives of this field were also provided for reference. Apart from presenting an overview of progress made in the field of PI porous monoliths, this review could also be meaningful for those researching topics which have similarity within.

摘要 : Using linear-stability analysis, two-dimensional modulation instability (MI) of plane wave is studied in nonlocal media with competing cubic–quintic (CQ) nonlinearities, which shows that MI can be effectively eliminated by strong nonlocality and competing quintic nonlinearity. Furthermore, propagation properties of higher-order soliton clusters, i.e., Hermite–Gaussian (HG) and Laguerre–Gaussian (LG) solitons are also investigated. Bifurcated solutions of these solitons are obtained analytically with variational approach. We also demonstrate in detail the propagation dynamics of the HG and LG solitons with split-step Fourier transform.

摘要 : Pyrethroids are widely used insecticides worldwide, while their on-site and rapid detection still faces technological challenges. Herein, an innovative detection mechanism was designed for deltamethrin, a typical kind of type II pyrethroids, based on a dual-emitting fluoroprobe consisting of NH 2 -SiQDs and Eu 3+ . Deltamethrin can rapidly hydrolyze into 3-phenoxybenzaldehyde (3-PBD) and react specifically with fluoroprobe, causing fluorescence quenching of SiQDs while maintaining the fluorescent stability of Eu 3+ . Building upon the above fluorescence-responsive principle, SiQDs@Eu 3+ provided satisfactorily dual-emitting signals, realizing the highly-selective and sensitive detection of deltamethrin. Correlation between the surface structure of SiQDs and their absorption spectra was in-depth unraveled by TD-DFT calculation and FT-IR analysis. As for the analytical performance, the recovery and LOD of deltamethrin in lettuce, provided by SiQDs@Eu 3+, were comparable or even superior over conventional chromatographic analysis. Meanwhile, an innovative smartphone-based optical device was developed, which greatly decreased errors caused by the previously reported smartphone-based fluorescence detection.

摘要 : The main challenges (sluggish electron transfer, low energy density) hinder the future application of enzymatic biofuel cells (EBFCs), which urgent to take effective measures to solve these issues. In this work, a composite of Au nanoparticles decorated graphdiyne (AuNPs@GDY) is fabricated and employed as the carrier of enzyme (G6PDH), and a mechanism based on π-π interaction of electron transfer is proposed to understand bioelectrocatalysis processes. The results show that the AuNPs@GDY composite exhibits the highest current density among the three materials (GDY, AuNPs, and AuNPs@GDY), which is 3.4 times higher than that of GDY and 2.5 times higher than that of AuNPs. Furthermore, the results reveal that the AuNPs could increase the loading of enzymes and provide more active site for reaction, while GDY provides highly π-conjugated structure and unique sp/sp 2 -hybridized linkages interface. This work provides new insights to explore a theoretical basis for the development of more efficient bioelectrocatalytic systems.

摘要 : Bi 2 S 3 is regarded as one of the most promising thermoelectric materials because of its abundance, cost-effectiveness and environmentally friendly characteristics. This work delves into the impact of interstitial Cu on the composition, microstructure, and thermoelectric properties of the Cl-doped Bi 2 S 3 bulks. The introduction of interstitial Cu as donors generates free electrons without compromising electron mobility. The excessive Cu induces the precipitation of Cu/Bi-rich phase and the Cu ions dynamically diffuse from these precipitates into the Bi 2 S 3 lattice with increasing temperature. This effect significantly enhances electrical conductivity and power factor across a broad temperature range. Intriguingly, dense nanodomains are successfully constructed in the Bi 2 S 3 sample. This unique defect, coupled with interstitial Cu, nanodomains, precipitates, and dislocations, establishes the hierarchical structures, leading to a low lattice thermal conductivity of 0.34 W m −1 K −1 . Notably, the sample incorporating 4 at% Cu achieves an exceptional peak ZT value of 0.67 at 673 K.