Simultaneously achieving high gravimetric capacitance and volumetric capacitance remains a major challenge in the development of supercapacitor electrode materials. A class of hollow carbon nanobowls (HCNBs) with a unique semiconcave geometry has been synthesized by a facile template method. The HCNBs can serve as a nanoreactor for the in situ space-confined growth of ultrasmall size, few layer two-dimensional (2D) molybdenum disulfide (MoS2) nanosheets. When used as the electrode materials for supercapacitors, the MoS2 nanosheets inside HCNBs named MoS2@HCNBs demonstrated outstanding gravimetric capacitance (560 F g–1 at 0.2 A g–1) and volumetric capacitance (874 F cm–3) at the same time. The cycling performance of MoS2@HCNBs (94.4% capacitance retention after 5000 cycles) is also much higher than HCNB@MoS2 in which the surfaces of HCNBs were covered by the 2D MoS2 nanosheets. Several factors have been leading to the boosted performance, and the mechanisms have been analyzed. The HCNBs with high surface area, developed porosity, and ultrathin carbon shells promote the rapid electrolyte penetration and provide a conductive pathway for excellent ion and electron transport. The ultrasmall few layer MoS2 nanosheets inside the HCNBs help to induce extra electrochemical double-layer capacitance as well as higher pseudocapacitance. More importantly, the semiconcave HCNBs can protect the structural stability of MoS2 nanosheets and contribute an enhanced packing density to further improve the volumetric capacitance of the hybrid MoS2@HCNBs.
Potatoes from various parts of New Brunswick, Canada, were tested for leaf roll virus by means of aphid vectors and the indicator plant P. floridana. Only moderate strains of the virus were recovered, always from plants that developed clear symptoms of leaf roll. There was no conclusive evidence that any of the potatoes were infected by mild strains that do not cause leaf rolling in potatoes. When Kennebec plants from various sources were inoculated with a moderate strain of the virus, all of them became infected showing that they were not already infected by mild strains that protect against stronger ones. Mild strains of leaf roll were not recovered from supposedly infected tubers obtained from western Canada. Nor was the virus recovered from these same clones during concurrent tests made in western Canada by one of those who made the original diagnosis of infection some years ago. Possible reasons from these unexpected results are mentioned. In any event there is no reason to believe that mild strains of leaf roll are common in New Brunswick.
Abstract Interfacial effects of a multifunctional additive (MFA), i.e. n ‐tallow‐1,3‐propanediamine salt of a carboxylic acid, on carbon black filled rubber have been studied. Surfaces of several normal cure rate carbon blacks were characterized by XPS and vapour‐phase chemical derivatization, and the carbon blacks were found to have very few functional groups on their surfaces. The MFA has been found to decompose at ∼120 °C and the decomposition generates a diamine and a carboxylic acid. Bound rubber, determined by o ‐xylene extraction, was found to decrease with the addition of MFA and a limiting bound rubber value was obtained at the MFA loading which corresponds to a monolayer coverage of the carbon black. The reduction of bound rubber with the addition of MFA is attributed to the release of the occluded rubber within carbon black agglomerates as a result of improved dispersion induced by the MFA. Mechanical properties were found to improve with the addition of MFA and the improvement was again attributed to the dispersing effect of MFA. Optimum mechanical properties were again observed to occur at an MFA loading which approximately corresponds to a monolayer coverage of the carbon black surface.
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