2,2',4,4'-Tetrabromodiphenyl Ether (BDE-47) at Environmental Levels Influenced Photosynthesis in the Mangrove Species Kandelia obovata.

2,2',4,4'-tetra-bromodiphenytol ether (BDE-47) is one of the ubiquitous organic pollutants in mangrove sediments. To reveal the toxic effects of BDE-47 on mangrove plants, the mangrove species Kandelia obovate was used to investigate the photosynthetic capacity effects and the molecular mechanisms involved after BDE-47 exposure at environment-related levels (50, 500, and 5000 ng g-1 dw). After a 60-day exposure, the photosynthetic capacity was inhibited in K. obovata seedlings, and a decrease in the stomatal density and damage in the chloroplast ultrastructure in the leaves were found. Transcriptome sequencing showed that, following exposure to BDE-47, gene expression in photosynthesis-related pathways was predominantly suppressed in the leaves. The bioinformatics analysis indicated that BDE-47 exerts toxicity by inhibiting photosystem I activity and chlorophyll a/b-binding protein-related genes in the leaves of K. obovata. Thus, this study provides preliminary theoretical evidence for the toxic mechanism effect of BDE-47 on photosynthesis in mangrove species.

Respiratory substrate preferences in mitochondria isolated from different tissues of three fish species.

Energy requirements of tissues vary greatly and exhibit different mitochondrial respiratory activities with variable participation of both substrates and oxidative phosphorylation. The present study aimed to (1) compare the substrate preferences of mitochondria from different tissues and fish species with different ecological characteristics, (2) identify an appropriate substrate for comparing metabolism by mitochondria from different tissues and species, and (3) explore the relationship between mitochondrial metabolism mechanisms and ecological energetic strategies. Respiration rates and cytochrome c oxidase (CCO) activities of mitochondria isolated from heart, brain, kidney, and other tissues from Silurus meridionalis, Carassius auratus, and Megalobrama amblycephala were measured using succinate (complex II-linked substrate), pyruvate (complex I-linked), glutamate (complex I-linked), or combinations. Mitochondria from all tissues and species exhibited substrate preferences. Mitochondria exhibited greater coupling efficiencies and lower leakage rates using either complex I-linked substrates, whereas an opposite trend was observed for succinate (complex II-linked). Furthermore, maximum mitochondrial respiration rates were higher with the substrate combinations than with individual substrates; therefore, state III respiration rates measured with substrate combinations could be effective indicators of maximum mitochondrial metabolic capacity. Regardless of fish species, both state III respiration rates and CCO activities were the highest in heart mitochondria, followed by red muscle mitochondria. However, differences in substrate preferences were not associated with species feeding habit. The maximum respiration rates of heart mitochondria with substrate combinations could indicate differences in locomotor performances, with higher metabolic rates being associated with greater capacity for sustained swimming.

Facile Fabrication of Dual Functional Graphene Oxide Microcapsules Carrying Corrosion Inhibitor and Encapsulating Self-Healing Agent.

Dual functional graphene oxide (GO) microcapsules were fabricated through self-assembly in Pickering emulsions, carrying corrosion inhibitor benzotriazole (BTA) on the microcapsule shells and encapsulating a self-healing agent epoxy monomer. The formation of the GO microcapsules was assisted by the interaction between BTA and GO, which provided robust encapsulation for the epoxy monomer. The loading capacity of BTA and epoxy monomer reached 90.5%. The addition of the GO microcapsules simultaneously promoted the corrosion protection and self-healing properties of the waterborne epoxy composite coatings. The healing efficiency of the composite coatings reached over 99.7% when the content of the microcapsules was 10 wt%. Meanwhile, the corrosion current density of the intact coatings was decreased for around 50 times.

Acute Cd Toxicity, Metal Accumulation, and Ion Loss in Southern Catfish (Silurus meridionalis Chen).

The amounts of cadmium in multiple organs and the amounts of Na+ and Ca2+ in the carcass were measured in dead and surviving southern catfish exposed to different concentrations of Cd. The 96 h median lethal concentration was 6.85 mg/L. The Cd content and Cd accumulation rate were positively correlated with Cd exposure concentrations, and there were significant differences between dead and surviving individuals, indicating that both Cd content in tissues and Cd accumulation rates were correlated with mortality. Cd levels in the liver of dead fish were saturated. A lethal threshold for Cd concentration in the whole fish was obtained. Bioconcentration factors for Cd did not decrease with increasing exposure. Acute exposure to waterborne Cd caused a significant decrease in the ion content of the fish carcass. There was a significant difference between the Na+ content of the carcass of dead fish (34.54 µmol/g wet weight) and surviving fish (59.34 µmol/g wet weight), which was not the case with the Ca2+ content, indicating that the lethal toxicity of Cd was probably related to the decrease in Na+ content. Collectively, these results suggest that whole-fish Cd concentration and carcass Na+ content can be useful indicators of fish acutely exposed to Cd.

Effects of waterborne cadmium exposure on Spinibarbus sinensis hepatopancreas and kidney: Mitochondrial cadmium accumulation and respiratory metabolism.

To examine the relationship between heavy metal accumulation in mitochondria and their respiration function in fish during in vivo exposure, juvenile Spinibarbus sinensis were exposed to different waterborne cadmium (Cd) concentrations for up to 28 days. We measured the state III respiration rate and cytochrome c oxidase (CCO) activity of mitochondria in hepatopancreas and kidney and the accumulated Cd concentrations in mitochondria and heat-stable protein (HSP) fractions. Dose- and time-dependent Cd accumulation occurred at different levels in both organs, but was lower in hepatopancreas. When hepatopancreas mitochondrial Cd concentrations in Cd-exposed groups were > 5.5 µg/g dwt, their state III respiration rates were significantly lower than the control. CCO activity of hepatopancreas mitochondria exhibited decreasing dose- and time-dependent trends. However, kidney mitochondria respiratory activities were not affected significantly by Cd exposure. Cd concentrations in kidney HSP fraction were 2-5 times higher than in hepatopancreas under all exposure conditions, and were mainly present as non-deleterious metallothionein (MT)-Cd complexes. These results suggest that Cd accumulation occurred in hepatopancreas and kidney mitochondria of S. sinensis following waterborne Cd exposure, which significantly inhibited the respiration function of hepatopancreas mitochondria but did not have a deleterious effect on kidney mitochondria. The inhibitory pattern of hepatopancreas mitochondrial Cd concentrations related to function exhibited threshold and saturation effects, suggesting the capacity of S. sinensis to manage Cd toxicity. The difference in the relative proportion of Cd occurring as MT-Cd complexes in organs likely causes the organ-specific effects of Cd on hepatopancreas and kidney mitochondrial function.

Dual-Emission Ratiometric Fluorescent Probe Based on Lanthanide-Functionalized Carbon Quantum Dots for White Light Emission and Chemical Sensing.

Herein, we develop a novel method to synthesize lanthanide-functionalized carbon quantum dots via free-radical copolymerization using the methyl methacrylate (MMA) monomer as a functional monomer and introducing a lanthanide complex to obtain the dual-emission fluorescent composite material FCQDs-Ln(TFA)3 (Ln = Eu, Tb; TFA: trifluoroacetylacetone). The obtained composites were fully characterized, and their structures were investigated by Fourier transform infrared spectroscopy (FTIR), 1H NMR spectroscopy, X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). Subsequently, a series of white-light-emitting polymer composite films FCQDs- (Eu:Tb)(TFA)3/poly(methyl methacrylate) (PMMA) were designed and synthesized by adjusting the ratio of Eu(TFA)3/Tb(TFA)3 under different wavelengths. More significantly, FCQDs-Tb(TFA)3 was selected as a sensitive probe for sensing metal cations due to excellent photoluminescence properties, revealing a unique capability of FCQDs-Tb(TFA)3 of detecting Fe(III) cations with high efficiency and selectivity. Furthermore, the sensing experiment results indicated that FCQDs-Tb(TFA)3 is ideal as a fluorescent nanoprobe for Fe3+ ion detection, and the lowest detection limit for Fe3+ is 0.158 µM, which is superior to many other previous related research studies. This pioneering work provides a new idea and method for constructing a dual-emission ratio sensor based on carbon quantum dots and also extends the potential application in the biological and environmental fields.

In situ polymerization of graphene-polyaniline@polyimide composite films with high EMI shielding and electrical properties.

With the increasing demands of the electronics industry, electromagnetic interference (EMI) shielding has become a critical issue that severely restricts the application of devices. In this work, we have proposed a "non-covalent welding" method to fabricate graphene-polyaniline (Gr-PANI) composite fillers. The Gr sheets are welded with PANI via π-π non-covalent interactions. Furthermore, a flexible polyimide (PI) composite film with superior EMI shielding effectiveness is prepared by in situ polymerization. The 40% content of Gr-PANI10:1 (the mass ratio of Gr to PANI is 10 : 1) shows a superior electrical conductivity (σ) as high as 2.1 ± 0.1 S cm-1, 1.45 times higher than that of Gr@PI film at the same loading. Moreover, the total shielding effectiveness (SET) of EMI of the Gr-PANI10:1@PI reaches ∼21.3 dB and an extremely high specific shielding effectiveness value (SSE) of 4096.2 dB cm2 g-1 is achieved. Such a "non-covalent welding" approach provides a facile strategy to prepare high-performance PI-based materials for efficient EMI shielding.

Modified graphene/polyimide composite films with strongly enhanced thermal conductivity.

With the development of portable electronic devices, highly efficient thermal management has become an important design consideration which requires good flexibility and excellent thermal conductivity. In this work, an integrated "modified-welding" method is used to deliver a flexible film with superior thermal conductivity. Firstly, graphene oxide (GO) is modified by 4,4'-diaminodiphenyl ether (ODA) through covalent bonding, aiming at providing reactive sites by polyimide (PI) on GO sheets for further in situ "modified-welding". The intercalated PI in mGO film layers serves as the solder to weld adjacent graphene sheets into large ones with less grain boundaries, leading to a superior in-plane thermal conductivity of the graphitized graphene/polyimide composite film (g-mGO/PI) which reaches 1352 ± 5 W m-1 K-1, 92.3% higher than that of the pristine graphitized graphene film (g-GO). Additionally, the g-mGO/PI film survives a 2000-cycle anti-bending test, which demonstrates excellent flexibility. Last but not least, the "modified-welding" strategy also provides an innovative way to develop graphene-based films for thermal management.

Electrochemical behaviors of double-walled carbon nanotubes encapsulating ferrocene.

Electrochemical properties of a novel nanohybrid material, ferrocene-filled double-walled carbon nanotubes (Fc@DWNTs), have been successfully investigated for the first time by preparing different kinds of Fc@DWNTs modified glassy carbon electrodes. One pair of surface-confined redox waves corresponding to the couple of Fc/Fc+ is obtained, indicating Fc encapsulated in DWNTs retains electrochemical activity. Significantly differing from those of ferrocene-filled single-walled carbon nanotubes (Fc@SWNTs), Fc@DWNTs shows a specific electrochemical behavior, typically exhibiting thin-layer electrochemical characteristics at low scan rates, whereas diffusion-confined characteristics at high scan rates. The results indicate that the novel nanohybrid material possessing excellent electrochemical properties may have possible applications in constructing specific chemical and biological sensors.

Facile and scalable route for highly efficient enrichment of semiconducting single-walled carbon nanotubes.

Purely semiconducting single-walled carbon nanotubes (s-SWNTs) with a narrow diameter distribution have been produced for HiPco SWNTs. A facile technique combining microwave irradiation with mixed-acid-assisted dispersion has proven efficient for enrichment of s-SWNTs. Using this process, both electronic type-dependent (metallic versus semiconducting) and diameter-dependent separation of SWNTs were simultaneously realized. By mildly controlling experimental conditions, metallic single-walled carbon nanotubes (m-SWNTs) and smaller s-SWNTs were preferentially removed, yielding purely diameter distribution-narrowed semiconducting nanotubes. Furthermore, the chemical structure of carbon nanotubes was restored after thermal annealing, as indicated by Raman and UV absorption investigations. The dual effects of semiconducting enrichment and diameter distribution narrowing, along with facile procedures, make this method promising for large-scale separation of SWNTs and therefore for industrial fabrication of nanotube-based electronics.

Controllable preparation of triple-walled carbon nanotubes and their growth mechanism.

Triple-walled carbon nanotubes (TWNTs) with three concentric cylindrical graphene layers have been selectively synthesized for the first time from decomposition of ferrocene encapsulated inside double-walled carbon nanotubes, and were identified by high-resolution transmission electron microscopy (HRTEM) and Raman spectroscopy; HRTEM observations reveal that the formation of inner tubes of TWNTs follows a base-growth mechanism.