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Том 469, № 2 (2016)
- Год: 2016
- Статей: 3
- URL: https://journals.rcsi.science/0012-5016/issue/view/9199
Physical Chemistry
Energies of π*- and π-states of the conduction band and valence band of chiral carbon nanotubes
Аннотация
Nanotubes (NTs) are mainly represented by (n,p) chiral NTs with chirality indices 0 < p < n delimited by (n,0) and (n,n) for achiral NTs. In (n,p) chiral NTs, the unit cell hexagons have a helical arrangement on the cylindrical surface of an NT and common angular and axial translations. An analytical formula was derived for calculation of the band structure of both chiral and achiral NTs with chirality indices 0 ≤ p ≤ n and band diagrams of some chiral NTs. Chiral NTs significantly extend the range of semiconducting NTs. An equation for the band gap width ΔЕ of semiconducting chiral and achiral NTs was derived: \(\frac{{\vartriangle E}}{{{\gamma _0}}} = \frac{{2\pi }}{{\sqrt {3{n^2} + 3np + 3{p^2}} }}\). Tables of the band structure parameters of metallic and semiconducting chiral NTs are presented.
111-116
Ignition of highly reactive metal particles
Аннотация
It was shown that, with increasing reaction rate constant above a certain limit, the bulk ignition mechanism changes to a surface mechanism. In this case, surface layers of a particle undergo local heating and a reaction front forms and propagates into the particle. The time of the frontal burnout of the particle is shorter than the time of its bulk burnout, during which the temperature field relaxes instantaneously.
117-120
Rheological properties of poly(ethylene glycol) solutions and gels
Аннотация
By the interaction of a water–glycol solution of poly(ethylene glycol) (PEG) with calcium chloride dihydrate, a gel was produced. It was determined that, below a certain shear rate, this gel is a Newtonian fluid; however, above a certain shear rate, which depends on the gel viscosity, the properties of this gel are anomalous: the gel flow instantaneously completely stops. The viscosity of the gels was found to exponentially increase with increasing concentration of the cross-linking metal at constant PEG concentration. The density of the gels linearly increases with increasing concentration of the cross-linking metal at constant PEG concentration.
121-123