Degree Sums and Covering Cycles

It is shown that if in a simple graph G of order n the sum of degrees of any three pairwise non-adjacent vertices is at least n, then there are two cycles (or one cycle and an edge or a vertex) of GF that contain all the vertices. © 1995 John Wiley & Sons, Inc.     

Prompt Gamma-Ray Analysis of Rats

Prompt -ray analysis with the internal monostandard method was used to organs taken from rats. After B or Cd was administered, the B/H and Cd/H contents ratios were determined in the brain, kidney, and liver to study their distribution and metabolism. Boron was distributed in all organs but metabolized quickly. Cd was slowly accumulated in the liver and kidneys during the 65 hours studied but no Cd was detected in the brain.     

Change of concentrations of trace elements and protein contents in the liver of zinc deficient mice

The concentrations of essential trace elements and proteins in cytosolic fraction of hepatic cells of mice fed with Zn-deficient diet (Zn-def, mice) and control were determined by ICP-MS and BCA protein assay method, respectively, after division into forty fractions by gel filtration chromatography. The concentrations of zinc and proteins decreased in the 14–17th fractions of Zn-def, mice, whereas cobalt concentrations increased in the 14, 17, and 18th fractions. However, no significant differences were found on the gel after SDS-PAGE for the 12–21st fractions, although the BCA protein assay date showed the decrease of protein amounts in 13–15th fractions of Zn-def. mice.     

Multitracer study on permeation of rare earth elements through a supported liquid membrane

Separation by means of supported liquid membranes is a useful method for the preparation and preconcentration of radioactive nuclides. The permeation of rare earth elements through a bis(2-ethylhexyl) hydrogen phosphate-decalin membrane supported on a microporous polytetrafluoroethylene sheet was studied using a multitracer containing radioactive nuclides of Sc, Zr, Nb, Hf, Ce, Pm, Gd, Yb, and Lu. Permeation rates of these elements from feed solutions of various acidity to receiving solutions of 0.5 mol·dm⁻³ HCl were determined simultaneously. The feed solution at pH 1.4 gave the highest permeation rate for Ce, Pm, and Gd, amounting to about 95% of permeation for Ce and Pm, 80% for Gd, and 10% for Yb in 21 h. Scandium, Zr, Nb, Hf, and Lu were not transported at all from the feed solution. Permeation rates of Yb and Lu from the feed solution at pH 1.4 to receiving solutions of 0.75, 1.0, 2.3, and 4.0 mol·dm⁻³ HCl increased with the concentration. The results obtained indicate that the light rare earth elements can be separated from the heavy ones by this method.     

Dependence of selective enclathration on types of cholic acid crystals

Competitive recrystallizations of cholic acid (CA) from 1:1 binary mixtures of seven mono-substituted benzenes are demonstrated. The order of preference for guests to be incorporated into the cholic acid crystals are as follows: benzene, toluene > n-amylbenzene, n-hexylbenzene > ethylbenzene, n-propylbenzene, n-butylbenzene. These seven compounds afford bilayer type inclusion crystals that are classified into four types based on the host frameworks and host-guest stoichiometries. The order of selective enclathration corresponds to the four types as follows: 1:1 alpha G > 2:1 alpha G > 1:1 beta T or 2:1 alpha T. The preference for the alpha G type was also confirmed by investigating the host frameworks of the crystals obtained from binary mixtures. The dependence of the selectivity on the different types of CA crystals can be understood in terms of the fit of the guest molecule in the host cavity.     

NMR and MO Studies on the Molecular Structure of a Fluoranthene-Benzene Complex

Summary. Fluoranthene (FA) forms a 1:1 van der Waals complex with benzene in cyclohexane. The ¹H NMR spectrum of this complex shows that the FA moiety in the complex state has five kinds of hydrogen atoms and that the ¹H NMR peaks assigned to the protons attached to the naphthalene skeleton are largely shifted to higher magnetic field on complex formation with benzene. These observations indicate that the complex takes the structure of C_S symmetry, in which the benzene molecule mainly interacts with the electronic system localized on the naphthalene moiety of FA. The present ab initio calculations reproduce well the ¹H NMR spectral shifts mentioned above and the experimentally predicted C_S structure of the complex. According to the PPP calculations for the electronic absorption spectral changes on the complex formation, the FA-benzene complex is considered to take a sandwich type structure.