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1.
2.
Let G be a set of n points in general
position (i.e., no three points are on a line)
in the plane, and let C be a caterpillar on n vertices.
We show that one can always find a rectilinear embedding of C in the plane
such that the vertices of C are the points of G and no two edges of C
go to parallel segments. This proves a conjecture of
Robert E. Jamison. 相似文献
3.
4.
Dávid Szegvári Romána Zelkó Péter Horváth András Gergely 《Journal of inclusion phenomena and macrocyclic chemistry》2007,57(1-4):169-172
Enantioselective solubility of rac-norgestrel was found in the presence of γ-cyclodextrin or hydroxypropyl-γ-cyclodextrin.
In both cases the efficacious enantiomer was dissolved in greater extent. Calculating the molar absorptivity and molar ellipticity
spectra of the γ- and hydroxypropyl-γ-cyclodextrin aqueous complexes, a simple and rapid direct circular dichroism (CD) spectrometric
method was obtained for the determination of the enantiomer ratio in aqueous solutions. 相似文献
5.
G. N. Kozhemyakin D. V. Lutskiy M. A. Rom P. V. Mateychenko 《Crystallography Reports》2008,53(7):1267-1271
The growth conditions and structural quality of Sb-Bi gradient single crystals with Bi content from 2 to 18 at %, grown by
the Czochralski method with solid phase feed, are investigated. Bi distribution in the crystals along their pulling direction
are studied by electron probe microanalysis and the change in the interplanar spacing is analyzed by double-crystal X-ray
diffraction. It is established that the pulling rate and feed mass affect the Bi distribution in Sb-Bi single crystals. 相似文献
6.
Let C be a family of n different unit circles in the plane. We show that C determines at least n - c intersection points,
where c is the number of connected components in ∪C ∈ CC. This proves a conjecture of A. Bezdek. 相似文献
7.
F. Román S. Montserrat J. M. Hutchinson 《Journal of Thermal Analysis and Calorimetry》2007,87(1):113-118
The procedure for
the fabrication of epoxy-based polymer layered silicate nanocomposites is
important in respect of the nanostructure that is developed. To further our
understanding of this, the influence of an organically modified clay (montmorillonite,
MMT) on the curing kinetics of an epoxy resin has been studied by differential
scanning calorimetry. Clay loadings of 10 and 20 mass% are used, and isothermal
as well as dynamic cures have been investigated. For both cure schedules the
effect of the MMT is to advance the reaction. Kinetic analysis yields values
for the activation energy, but shows that the reaction cannot be described
simply by the usual autocatalytic equation. The glass transition of the cured
nanocomposites is lower than that for the cured neat resin, a result that
is attributed to homopolymerisation taking place in addition to the epoxy–amine
reaction. 相似文献
8.
9.
Extensive molecular dynamics simulations have been done to study the evaporation of a 13-atom Lennard-Jones cluster. The survival probability and the evaporative lifetime are calculated as a function of the cluster total energy from a classical trajectory analysis. The results are interpreted in terms of the RRK theory of unimolecular dissociation. The calculation of the binding energy of the evaporated species from the evaporation rate and the average kinetic energy release is discussed. 相似文献
10.
Togashi DM Romão RI Gonçalves da Silva AM Sobral AJ Costa SM 《Physical chemistry chemical physics : PCCP》2005,7(22):3874-3883
Langmuir monolayers (LM) and Langmuir-Blodgett (LB) films of pure lipophilic meso-tetra(4-dodecylaminosulfophenyl)porphyrin (PC12) and mixed with the anionic surfactant sodium hexadecylsulfate (SHS) were studied. The molecular packing and structure of PC12 and PC12-4SHS with variable surface pressure were investigated by surface pressure-area measurements, steady-state absorption, fluorescence emission and anisotropy, as well as by fluorescence lifetime imaging microscopy (FLIM). At low surface pressure, the porphyrin molecules are organized with the rings tilted on the water surface whereas at high surface pressure the porphyrin rings achieve a more perpendicular arrangement. Using the FLIM images a gradual change of aggregates into large "islands" is observed. Different patterns are observed in the pure PC12 multilayer films (n = 3 and 5) with ordered patches superimposed which are not observed in the PC12-4SHS multilayer LB films. 相似文献