摘要 : Thimerosal (THI) is the most widely used form of organic mercury in pharmaceutical and personal care products, and has become a major source of ethylmercury pollution in aquatic ecosystems. However, knowledge about its potential risk to aquatic species is limited. In this study, zebrafish were exposed to THI for 7 days, and variations in their behavioral traits, brain monoaminergic neurotransmitter contents, and related gene expression were investigated. After the 7-day exposure, THI reduced locomotor activity and thigmotaxis in males but not females. Exposure to THI increased the social interaction between females but decreased that between males. The THI exposure also significantly reduced the serotonin (5-HT), 5-hydroxyindoleacetic acid, dopamine (DA), and 3, 4-dihydroxyphenylacetic acid contents in the brain of males, but only significantly decreased the DA content in females. Correlation analysis revealed that the neurochemical alterations in the brain of zebrafish play critical roles in the behavioral abnormalities induced by THI exposure. Moreover, THI also significantly altered the expression of some genes associated with the synthesis, metabolism, and receptor binding of 5-HT and DA in the brain of zebrafish. The differences in these gene expressions between female and male zebrafish exposed to THI seem to be an important mechanism underlying their sex-specific responses to this chemical. This is the first report on the sex-specific effects of THI on behaviors and brain monoaminergic neurotransmitter contents in zebrafish, which can further improve our understanding of its toxic effects on teleost.

摘要 : Various phthalic acid esters (PAEs) such as dibutyl phthalate (DBP) and butyl benzyl phthalate (BBP) co-exist with nanopollutants in aquatic environment. In this study, Daphnia magna was exposed to nano-CuO and DBP or BBP at environmental relevant concentrations for 21-days to investigate these combined toxic effects. Acute EC 50 values (48 h) of nano-CuO, DBP, and BBP were 12.572 mg/L, 8.978 mg/L, and 4.785 mg/L, respectively. Results showed that co-exposure with nano-CuO (500 μg/L) for 21 days significantly enhanced the toxicity of DBP (100 μg/L) and BBP (100 μg/L) to Daphnia magna by 18.37% and 18.11%, respectively. The activities of superoxide dismutase, catalase, and glutathione S-transferase were enhanced by 10.95% and 14.07%, 25.63% and 25.91%, and 39.93% and 35.01% in nano-CuO+DBP and nano-CuO+BBP treatments as compared to the individual exposure groups, verifying that antioxidative defense responses were activated. Furthermore, the co-exposure of nano-CuO and PAEs decreased the population richness and diversity microbiota, and changed the microbial community composition in Daphnia magna . Metabolomic analysis elucidated that nano-CuO + PAEs exposure induced stronger disturbance on metabolic network and molecular function, including amino acid, nucleotides, and lipid metabolism-related metabolic pathways, as comparison to PAEs single exposure treatments. In summary, the integration of physiological, microflora, and untargeted metabolomics analysis offers a fresh perspective into the potential ecological risk associated with nanopollutants and phthalate pollution in aquatic ecosystems.

摘要 : Metal-organic frameworks (MOFs) have been used to detect uric acid (UA), but still very challenging to achieve a low detection limit due to the low inferior conductivity of MOFs. Herein, three different N-doped ZIF-67-derived carbons were synthesized for the first time by one-step co-pyrolysis of 2-methylimidazole with cobalt nitrate (CN), cobalt acetate (CA) or cobalt chloride (CC) toward UA sensing. Afterwards, the cobalt nitrate-derived Co particle (Co/CN) supported by N-doped ZIF-67-derived carbon displays extremely low detection limit and high sensitivity for UA, outperformed all reported MOFs-based UA sensors. More interestingly, it was discovered that the high valence Co 4+ within the Co/CN sample produced in high-acidic environment can intercalate in the frame for a bridge adsorption between two reaction sites, which boosted simultaneous 2-electron transfer, while Co 3+ only allows an end-adsorption structure for one-electron transfer being the rate determining step. Furthermore, the bridge adsorption mode of UA on Co 4+ -based catalyst was also verified by theoretical DFT calculations and XPS experiment. This work holds great promise for a selective and sensitive UA sensor for practical bioscience and clinic diagnostic applications while shedding lights in fundamental research for innovative designs and developments of high-sensitive electrochemical sensors.

摘要 : In order to investigate the response of offshore wind turbines (OWTs) under earthquake, shaking table test is conducted using a 6.45 MW OWT as prototype. The effective length of the embedded steel pile is determined using the equivalent embedment method, and a scale model with a similarity constant of 1:15 is designed. The dynamic characteristics of the scale model are evaluated through position-shift and white noise. Three earthquakes with different spectrum characteristics are utilized as inputs, and subsequently, an analysis is performed to assess the earthquake response of the OWT. The results demonstrate that the dynamic characteristics between the scale model and the prototype model meet the similarity constants. Due to the eccentric mass, torsional vibrations are induced when subjected to bidirectional excitation, resulting in the occurrence of 'beat vibration' phenomenon. The acceleration is significantly influenced by the excitation spectrum, with the maximum occurring at either the top or 2/3 height, and Darfield with wide spectrum result in a more pronounced stimulation. The displacements are all observed at the pinnacle of the tower. The Imperial and Kocaeli, characterized by shorter duration and higher energy concentration, elicit more pronounced displacement. Stress concentration occurs at the lower 1/3 due to sudden stiffness change.

摘要 : Squaraines (SQs) are a significant family of near-infrared dyes with applications in fluorescence bioimaging, photodynamic therapy, etc. Most efforts have been devoted to modulating their nonlinear absorption while their nonlinear refraction has been neglected. Here, near-infrared broadband nonlinear absorption and refraction in two squaraine derivatives ( SQ-640 and SQ-670 ) are investigated with Z-scan (720–1300 nm) and time-resolved pump-probe method. With essentially similar conjugation and planarity in the two molecules, the effect of alkyl cyclization on the nonlinear optical response is discussed. A larger transition dipole moment is reached via alkyl cyclization and results in a wider range of nonlinear optical responses for SQ-670 . In addition to conventional transient absorption measurement, transient nonlinear refraction based on phase contrast pump-probe method are used for the study of ultrafast dynamics. Kinetic details from both measurements are compared and analyzed for further details of ultrafast photophysical mechanisms in these molecules. Besides, an intensity-dependent transition from saturable absorption to reverse saturable absorption in SQ-670 is observed at 720 nm which is mainly due to the combined contributions of one-photon absorption and TPA. Both samples display good nonlinear absorption (NLA) at the near-infrared region (750–1300 nm) which originates from two-photon absorption (TPA) and TPA induced excited state absorption. Bound electron response and negative excited state refraction dominate the nonlinear refraction of both molecules. Our work gains a deeper understanding of the NLO properties of squaraine derivatives from an alternative perspective and enriches the experimental research on squaraine derivatives. It may provide a useful reference for the future design of organic materials with excellent nonlinear optical responses.

摘要 : Owing to the advantages of monolithic structure and little need for assembling, compliant guiding mechanisms appear to be an effective solution for decoupling multi-freedom precision motions but are still prone to geometric nonlinearities of parasitic error and stiffening effect for large strokes. This paper proposes a coiled L-shape compliant guiding mechanism featuring millimeter-scale strokes with a compact structure, constant stiffness, and minimized parasitic error. The coiled compliant guiding mechanism is formed by convolving L-shape flexure beams in a zigzag configuration with decoupled XY motions achieved. Its geometrically nonlinear parasitic error, variation in stiffness, and primary vibration are captured by using a dynamic beam constraint model (DBCM). It is theoretically, numerically, and experimentally found, by comparing with double parallel guiding mechanisms, that the kinetostatic and dynamic behaviors of the coiled L-shape compliant mechanism are nearly independent on the applied force within intermediate-deformation ranges. Such a weak geometric nonlinearity with the minimized influence of axially loaded stiffening and kinematics-arching effects is much different from the double parallel guiding mechanisms. The obtained results indicate that large strokes with constant stiffness and invariable resonance frequency can be realized, which also allows small parasitic errors.

摘要 : The majority of problematic invasive plants exhibit clonal growth, and the clonal traits are widely recognized as critical determinants contributing to their invasiveness. Division of labor represents a crucial advantage associated with clonal growth; therefore, it is reasonable to anticipate that this particular trait may confer a growth advantage upon invasive clonal species in comparison to native ones. To test this hypothesis, we conducted a comparative experiment in the greenhouse involving the highly invasive plant Alternanthera philoxeroides, its native congener A. sessilis, and its native co-occurring Jussiaea repens . We grew clonal fragments of these three stoloniferous plants under negative spatial covariance of light and soil nutrients while either preventing or allowing division of labor through severing or keeping intact their stolon connections. The results showed that stolon connection significantly increased the root mass to shoot mass ratio of basal ramets under low light and high soil nutrient conditions, but greatly decreased it in the apical ramets under high light and low soil nutrient conditions, suggesting induced division of labor in all studied plants. Moreover, the invasive plant A. philoxeroides demonstrated a greater capacity for division of labor than its co-genus and co-occurring native partners, which conferred it with greater growth performance at the whole clonal fragment level. Given that the commonly observed competitive superiority of invasive clonal plants over co-occurring native species due to their high intrinsic growth rates, these findings suggest that the division of labor may confer a competitive advantage upon some invasive clonal plants, thereby facilitating their successful invasion in heterogeneous habitats characterized by a strong negative correlation between light availability and soil nutrient levels.

摘要 : Currently, conversion-type transition metal sulfides have been extensively favored as the anodes for sodium-ion batteries due to their excellent redox reversibility and high theoretical capacity; however, they generally suffer from large volume expansion and structural instability during repeatedly Na + de/intercalation. Herein, spatially dual-confined Ni-doped CoS 2 @NC@C microrods (Ni-CoS 2 @NC@C) are developed via structural design, heteroatom doping and carbon confinement to boost sodium storage performance of the material. The morphology of one-dimensional-structured microrods effectively enlarges the electrode/electrolyte contact area, while the confinement of dual - carbon layers greatly alleviates the volume change-induced stress, pulverization, agglomeration of the material during charging and discharging. Moreover, the introduction of Ni improves the electrical conductivity of the material by modulating the electronic structure and enlarges the interlayer distance to accelerate Na + diffusion. Accordingly, the as-prepared Ni-CoS 2 @NC@C exhibits superb electrochemical properties, delivering the satisfactory cycling performance of 526.6 mA h g −1 after 250 cycles at 1 A g −1, excellent rate performance of 410.9 mA h g −1 at 5 A g −1 and superior long cycling life of 502.5 mA h g −1 after 1, 500 cycles at 5 A g −1 . This study provides an innovative idea to improve sodium storage performance of conversion-type transition metal sulfides through the comprehensive strategy of structural design, heteroatom doping and carbon confinement.

摘要 : Helium, as a probe gas with low adsorption capacity, is widely used for measuring porosity, permeability, and specific surface area in reservoir rocks of unconventional gas such as shale and coal. The pretreatment duration of these rock samples determines the amount of residual nitrogen in their pores, and the competitive adsorption and diffusion of residual nitrogen with the probe gas has a significant impact on the measurement results of their physical properties. This work aims to reveal the mechanisms involved in the competitive adsorption-diffusion coupling process of nitrogen-helium mixtures. Brief experiments were conducted to demonstrate the competitive adsorption between nitrogen and helium in shale. Subsequently, molecular dynamics simulation was employed to investigate this process and provide necessary details. Meanwhile, a theoretical model was developed to describe the diffusion of gas molecules in this process. Our results indicate that helium rapidly permeates shale samples and reaches an equilibrium distribution. However, the competitive adsorption between nitrogen and helium can slow down the helium permeation process, which can be attributed to the main adsorption sites occupied by nitrogen. The agreement between FEM computations and MD simulations validates our model for various mechanisms. Furthermore, our model can be applied to a wider range of porous materials and gas mixtures in related fields.

摘要 : The selection of separability and surface positive charge is of significant importance for treating acidic industrial wastewater with acid-resistant nanofiltration (NF) membranes. In this work, polyvinylidenefluoride (PVDF) flat membrane was used as the base membrane material, with polyethyleneimine (PEI) as the aqueous monomer and trimesoyl chloride (TMC)/benzene-1, 3-disulfonyl chloride (BDSC) as the organic phase monomers, to prepare PEI-polyamide-sulphonamide (PASA) NF membrane through interfacial polymerization (IP). The influence of reaction conditions on membrane separation performance and corrosion resistance were studied, and the performance differences of the membrane under different ratios of TMC and BDSC were explored. PEI-PASA NF membrane was characterized by FTIR, XPS, SEM, contact angle tester, and mechanical strength tester. The results showed that the PEI-PASA NF membrane prepared under optimal conditions had a strong positive charge on the surface, with a water flux of 17.54 L·m −2 ·h −1 at 5 bar, and after static assessments in 10 % H 2 SO 4 solution at 55 °C for 24 h, the methyl orange rejection remained kept over 95 %; after dynamic filtration in 1 % HCl for 120 h, the rejection performance of the membrane remained stable (FeCl 3 96.88 %, CuCl 2 93.72 %), indicating the potential application inharsh conditions, especially acid wastewater treatment.