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61.
V. V. Ivanovskaya G. Seifert A. L. Ivanovskii 《Russian Journal of Inorganic Chemistry》2006,51(2):320-324
The effect of doping transition metal disulfide nanotubes on their structural and electronic properties was studied for the first time using self-consistent band-structure calculations by the density functional tight-binding method (DFTB). The influence of partial Nb → Mo substitution in the walls of MoS2 nanotubes of various diameters and atomic configurations (armchair and zigzag) on their electronic structure, structural parameters, and relative stability is exemplified by a series of “mixed” Mo0.9Nb0.1S2 nanotubes. The electronic properties of Mo0.9Nb0.1S2 nanotubes are discussed as a function of the possible types of distribution of doping Nb atoms in the tubes. 相似文献
62.
Coloring linear hypergraphs: the Erdős–Faber–Lovász conjecture and the Combinatorial Nullstellensatz
Designs, Codes and Cryptography - The long-standing Erdős–Faber–Lovász conjecture states that every n-uniform linear hypergaph with n edges has a proper vertex-coloring using... 相似文献
63.
Oliver Pretzel 《Order》1995,12(2):135-147
We prove generalizations to chain groups, of Minty's Arc Colouring Lemma and its extension, the well-known Farkas Lemma. In these the orientation of the edges is replaced by an arbitrary chain.A function on a chain groupN isrepresentable if there exists a chainR such that (X)=R·X for allXN. Anorientation is a chain with values ±1. We prove that for a regular chain group a linear function that is representable by an orientation for each chainXN locally, is representable by an orientation globally. 相似文献
64.
The production of ultrafine silica particles is examined by modelling the processes in a flow plasma reactor. The model is based on the authors' experimental data on silica sand processing by use of thermal arc plasma. The free-molecular coagulation is assumed to be the dominant process for particle growth. This is carried out at fast cooling of the vapour, during its mixing with oxygen. The particle size distribution functions are calculated, and the influence of the chemical monomer generation and the mixing on their behavior is investigated. Comparison of the calculated and the experimental mean particle size is made.List of symbols
C
nl
collision frequency function, cm3/s
-
d
m
mean median diameter, nm
-
F
LN(d)
integral form of the particle size distribution function,%
-
g(t)
mixing function
-
k
Boltzmann's constant
-
k
1,k,k
rate coefficients, cm3/s
-
k
2,k
3
rate coefficiens, cm6/s
-
m
mass of the monomer, g
-
M
number of groups
-
T
absolute temperature, K
-
T
0
temperature of the hot vapour, K
-
T
E
temperature of SiO2 condensation, K
-
t
time, s
-
t
m
mixing time, s
-
t
c
colling time, s
-
z
0
monomer concentration, cm–3
-
z
n
,z
l
concentrations of particles in groups, cm–3
- z
n
total number concentration of particles (n=0, 1, M), cm–3
-
z
n
/(z
n
)(log d
n+1
–logd
n)
differential form of particle size distribution function
-
w
i
reaction rates (i=1, 2, 3), cm–3/s
- ,
cooling rates, K/s
-
coefficient of proportionality
- SiO
conversion rate of SiO,%
-
coefficient determined from the cooling rate, s–1
-
mass density of the particles, g/cm3
-
standard deviation
The authors gratefully acknowledge Prof. L. S. Polak from the Institute of Petrol Chemical Synthesis, Russian Academy of Science, for helpful discussions. 相似文献
65.
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68.
Seifert N Liu D Barnes A Albridge R Yan Q Tolk N Husinsky W Betz G 《Physical review. B, Condensed matter》1993,47(13):7653-7658
69.
70.
Mg(AlH(4))(2) was produced as a nanocrystalline powder by metathesis of NaAlH(4) and MgCl(2). Starting with a structure estimation which was developed from an evaluation of FTIR data and comparison of structural properties of two solvent adducts, quantum chemical calculations were performed on the density functional theory (DFT) level. The calculated atomic positions were used to simulate an X-ray powder diffraction pattern, based on a trigonal unit cell. The simulated pattern was congruent to experimental data. Thus, magnesium alanate exhibits a CdI(2) layer structure, the layers being formed by Mg atoms occupying the Cd sites and AlH(4) tedrahedra occupying the sites of the iodine atoms in CdI(2). 相似文献