Relationships between biodiversity and ecosystem functioning proxies strengthen when approaching chemosynthetic deep-sea methane seeps.

As biodiversity loss accelerates globally, understanding environmental influence over biodiversity-ecosystem functioning (BEF) relationships becomes crucial for ecosystem management. Theory suggests that resource supply affects the shape of BEF relationships, but this awaits detailed investigation in marine ecosystems. Here, we use deep-sea chemosynthetic methane seeps and surrounding sediments as natural laboratories in which to contrast relationships between BEF proxies along with a gradient of trophic resource availability (higher resource methane seep, to lower resource photosynthetically fuelled deep-sea habitats). We determined sediment fauna taxonomic and functional trait biodiversity, and quantified bioturbation potential (BPc), calcification degree, standing stock and density as ecosystem functioning proxies. Relationships were strongly unimodal in chemosynthetic seep habitats, but were undetectable in transitional 'chemotone' habitats and photosynthetically dependent deep-sea habitats. In seep habitats, ecosystem functioning proxies peaked below maximum biodiversity, perhaps suggesting that a small number of specialized species are important in shaping this relationship. This suggests that absolute biodiversity is not a good metric of ecosystem 'value' at methane seeps, and that these deep-sea environments may require special management to maintain ecosystem functioning under human disturbance. We promote further investigation of BEF relationships in non-traditional resource environments and emphasize that deep-sea conservation should consider 'functioning hotspots' alongside biodiversity hotspots.

The synthesis of nanocarbon-poly(ricinoleic acid) composite as a lubricant additive with improved dispersity and anti-wear properties.

Herein, a nanocarbon-poly(ricinoleic acid) composite as a lubricant additive with excellent oil-solubility and dispersity was synthesized using nanocarbon spheres (CNSs) and ricinoleic acid via a "one-pot" approach. The prepared composite was characterized via Fourier transform infrared spectrometry (FTIR), thermogravimetric analysis (TG), Raman spectroscopy (Raman) and X-ray diffraction (XRD). Scanning electron microscopy (SEM) showed that there was no obvious aggregation after surface modification of CNSs. Results demonstrated that the dispersion stability of the composite anti-wear additive in base lubricating oil was significantly optimized. The prepared nanocarbon-poly(ricinoleic acid) composite showed significantly improved stability and dispersity in base lubricating oil for 3 months without obvious precipitation. Tribological tests indicated that the composite lubricant additive exhibited an improved anti-wear performance and better wear resistance than pure CNS additives. The friction coefficients with the composite anti-wear additive dropped from 0.052 to 0.027, which was reduced by 48.1% compared with that of the TMT base lubricating oil. Furthermore, the composite additive is desirable for efficient anti-wear properties in base lubricating oil. The synergistic effect between modified CNSs and poly(ricinoleic acid) significantly improved the wear resistance of the base oil.

Synthesis and Characterization of Polycaprolactone Modified Trimellitate Nano-Lubricant.

The application of trimellitate (TMT) in the lubricating oil industry was seriously restricted because of its low viscosity index. In the work reported here, polycaprolactone (PCL) soft chain was embedded into the structure of TMT in order to improve the viscosity index. Characterization of the polymers was done by proton nuclear magnetic resonance (1H-NMR), Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TG). Results supported our design and were consistent with the target product structure. Performance of the prepared materials was evaluated by standard ASTM methods. Noticeably, the viscosity index of the modified TMT increased from 8 to above 100, which greatly improved its viscosity-temperature performance. As the initiator, tetrabutyl titanate (TBT) can not only complete the ring-opening polymerization of caprolactam (ε-CL) at room temperature, but also generate nano-TiO2 by-products with excellent anti-wear properties during the synthesis. Characterization of the nano-TiO2 was done by scanning electron microscopy (SEM), FT-IR, TG and X-ray diffractometry (XRD). The friction and wear tests were conducted on a four-ball friction tester and the surface morphologies of worn surfaces were investigated by SEM. The experimental results clearly showed that the modified TMT showed better viscosity index and thermal stability as compared to the unmodified one. The modified nano-TMT base oil features excellent lubricant performance with good viscosity-temperature properties, thermal stability and anti-wear properties.