Single-walled carbon nanotubes can be classified as either metallic or semiconducting, depending on their conductivity, which is determined by their chirality. Existing synthesis methods cannot controllably grow nanotubes with a specific type of conductivity. By varying the noble gas ambient during thermal annealing of the catalyst, and in combination with oxidative and reductive species, we altered the fraction of tubes with metallic conductivity from one-third of the population to a maximum of 91%. In situ transmission electron microscopy studies reveal that this variation leads to differences in both morphology and coarsening behavior of the nanoparticles that we used to nucleate nanotubes. These catalyst rearrangements demonstrate that there are correlations between catalyst morphology and resulting nanotube electronic structure and indicate that chiral-selective growth may be possible.
The results of numerical simulation of mass transfer in semidetached non‐magnetic binaries are presented. We investigate the morphology of gaseous flows on the basis of three‐dimensional gas‐dynamical calculations of interacting binaries of different types (cataclysmic variables and low‐mass X‐ray binaries). We find that taking into account a circumbinary envelope leads to significant changes in the stream–disc morphology. In particular, the obtained steady‐state self‐consistent solutions show an absence of impact between the gas stream from the inner Lagrangian point L1 and the forming accretion disc. The stream deviates under the action of the gas of the circumbinary envelope, and does not cause the shock perturbation of the disc boundary (traditional hotspot). At the same time, the gas of the circumbinary envelope interacts with the stream and causes the formation of an extended shock wave, located on the stream edge. We discuss the implication of this model without hotspot (but with a shock wave located outside the disc) for interpretation of the observations. The comparison of synthetic light curves with observations proves the validity of the discussed gas‐dynamical model without hotspot. We have also considered the influence of the circumbinary envelope on the mass transfer rate in semidetached binaries. The obtained features of flow structure in the vicinity of L1 show that the gas of the circumbinary envelope plays an important role in the flow dynamics, and that it leads to significant (in order of magnitude) increase of the mass transfer rate. The most important contribution to this increase is from the stripping of the mass‐losing star atmosphere by interstellar gas flows. The parameters of the formed accretion disc are also given in the paper. We discuss the details of the obtained gaseous flow structure for different boundary conditions on the surface of mass‐losing star, and show that the main features of this structure in semidetached binaries are the same for different cases. The comparison of gaseous flow structure obtained in two‐ and three‐dimensional approaches is presented. We discuss the common features of the flow structures and the possible reasons for revealed differences.
A sulfonamide-based electrolyte can greatly improve the cycling stability of the commercial LiCoO2 cathode at high cut-off voltages in Li metal||LCO batteries by stabilizing the electrode–electrolyte interfaces on both the anode and cathode.
We present the results of qualitative consideration of possible changes occurring during the transition from the hot accretion disc to the cool one. We argue the possible existence of one more type of spiral density waves in the inner part of the disc where gasdynamical perturbations are negligible. The mechanism of formation of such a wave as well as its parameters are considered.We also present the results of 3D gasdynamical simulation of cool accretion discs. These results confirm the hypothesis of possible formation of the spiral wave of a new, "precessional" type in the inner regions of the disc. Possible observational manifestations of this wave are discussed.
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