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21.
22.
Martin Ferus Svatopluk Civiš Petr Kubelík Václav Nevrlý Petr Bitala Eva Grigorová Michal Střižík Pavel Kubát Zdeněk Zelinger 《Plasma Chemistry and Plasma Processing》2011,31(3):417-426
The environmentally important decomposition of halogenated species CF3Br and CF3CHFCF3 in helium discharge plasma was investigated by time-resolved high-resolution Fourier transform infrared emission spectroscopy.
Contrary to classical pyrolysis, a deeper fragmentation of precursors up to atoms and lower molecular species was observed.
Excited molecular products CF, CF2 and CF4 achieved the maximal concentration in the afterglow. The high concentration of all these species is in agreement with a kinetic
model based on radical chemistry. The non-detectable concentration of CF3 can be connected to its high reactivity and the formation of more stable products, CF4 and CF2, by addition or release of a fluorine atom, respectively. Other products included HF, HBr, CO and cyano compounds that were
produced by secondary reactions with traces of water vapor, atmospheric oxygen and nitrogen present in original industrial
samples as impurities. 相似文献
23.
Kavan L Zukalova M Ferus M Kürti J Koltai J Civiš S 《Physical chemistry chemical physics : PCCP》2011,13(24):11583-11586
(18)O-isotope labelled titania (anatase, rutile) was synthesized. The products were characterized by Raman spectra together with their quantum chemical modelling. The interaction with carbon dioxide was investigated using high-resolution FTIR spectroscopy, and the oxygen isotope exchange at the Ti(18)O(2)/C(16)O(2) interface was elucidated. 相似文献
24.
Christoph Helmberg Franz Rendl Bojan Mohar Svatopluk Poljak 《Linear and Multilinear Algebra》1995,39(1):73-90
Lower bounds on the bandwidth, the size of a vertex separator of general undirected graphs, and the largest common subgraph of two undirected (weighted) graphs are obtained. The bounds are based on a projection technique developed for the quadratic assignment problem, and once more demonstrate the importance of the extreme eigenvalues of the Laplacian. They will be shown to be strict for certain classes of graphs and compare favourably to bounds already known in literature. further improvement is gained by applying nonlinear optimization methods. 相似文献
25.
The cut polytopeP n is the convex hull of the incidence vectors of the cuts (i.e. complete bipartite subgraphs) of the complete graph onn nodes. A well known class of facets ofP n arises from the triangle inequalities:x ij +x ik +x jk ≤ 2 andx ij -x ik -x jk ≤ 0 for 1 ≤i,j, k ≤n. Hence, the metric polytope Mn, defined as the solution set of the triangle inequalities, is a relaxation ofP n . We consider several properties of geometric type for Pn, in particular, concerning its position withinM n . Strengthening the known fact ([3]) thatP n has diameter 1, we show that any set ofk cuts,k ≤ log2 n, satisfying some additional assumption, determines a simplicial face ofM n and thus, also, ofP n . In particular, the collection of low dimension faces ofP n is contained in that ofM n . Among a large subclass of the facets ofP n , the triangle facets are the closest ones to the barycentrum of Pn and we conjecture that this result holds in general. The lattice generated by all even cuts (corresponding to bipartitions of the nodes into sets of even cardinality) is characterized and some additional questions on the links between general facets ofP n and its triangle facets are mentioned. 相似文献
26.
Jan Wild Jiří Macl Hana Šíchová Pavel Boháček Jarmila Prachařová Pavel Kubát Svatopluk Civiš 《Czechoslovak Journal of Physics》1997,47(10):1025-1030
Bi(Pb)–Sr–Ca–Cu–O layers were prepared by laser ablation in air, that is without using a vacuum chamber. At this method a much higher density of pulse energy of laser beam is required (10–30 J cm–2) in comparison with the standard method (1–3 J cm–2). The mentioned condition has specific effects on the nature of the transport of material from the target. As follows from the electron microprobe analysis of the layers, the starting composition of the transported material is identical with that of the superconducting phase sintered in the target; one exception represents Pb, the content of which in the transported material is lower. The image of the process is complemented by UV/VIS spectroscopy scans of the plasma plume. 相似文献
27.
A model for the distribution of cations in the spinel lattice of manganese ferrites MnFe2O4+
was elaborated on the basis of the experimental studies of the basic magnetic quantities, electrical conductivity and magnetic relaxation of the given ferrites, taking into consideration their crystallographic properties. The conclusions following from this model are in good agreement with the experimental results obtained by us and by other authors both for stoichiometric manganese ferrite and for a ferrite where 0.
I. MnFe2O4+
, MnFe2O4+ . , , , , , 0.相似文献
28.
We propose a simple model of society with a symmetric functionw(u, v) measuring the influence of the opinion of memberv on that of memberu. The opinions are chosen from a finite set. At each step everyone accepts the majority opinion (with respect tow) of the other members. The behaviour of such a society is clearly periodic after some initial time. We prove that the length of the period is either one or two. 相似文献
29.
Summary We prove existence and multiplicity theorems for nonlinear equations at resonance with expansive nonlinearities.
These results were obtained while the second author was visiting the University of Ferrara through a grant of C.N.R.
Supported by C.N.R., G.N.A.F.A. 相似文献
Riassunto Si provano teoremi di esistenza e molteplicità per equazioni nonlineari in risonanza con nonlinearità espansiva.
These results were obtained while the second author was visiting the University of Ferrara through a grant of C.N.R.
Supported by C.N.R., G.N.A.F.A. 相似文献
30.
The influence of the oxygen content on the saturation magnetic moment and the Curie temperature was studied experimentally on non-stoichiometric manganese ferrites having a varying excess of manganese. Taking into consideration the results of studying the electrical conductivity and magnetic relaxation effects, a model was elaborated for the distribution of ions in these ferrites, which starts out from the distribution of ions in stoichiometric manganese ferrite. The experimental results obtained by us and those of other authors confirm the justification of this model.
In conclusion the authors thank members of their technological department for preparing the samples and M. Mikulá for carefully carrying out the chemical analyses. 相似文献
II. Mn1+xFe2-xO4+y
. , . .
In conclusion the authors thank members of their technological department for preparing the samples and M. Mikulá for carefully carrying out the chemical analyses. 相似文献