Correlation of TLC/densitometry-data with capillary GC-data of some main volatile components of essential oils

The results of the densitometric and the capillary gas chromatographic investigations of numerous lavender oils of different origin and of essential oils of the woody group were correlated. Especially the main components, the monoterpenes linalool (¯1) and linalyl acetate (¯2), were quantified by densitometry with an average standard deviation of 6–7% in the examined oils. The use of TLC in combination with densitometry in the quantification of the main components to essential oils is thus a valuable addition to capillary gas chromatographic investigation. In addition to this, a useful and efficient alternative is given to groups specialized in TLC/densitometry to obtain data on such volatile compounds of essential oils during quantification. The use of TLC/densitometry thus combines the advantage of LC-with detection of also less volatile compounds—and the possibility of the parallel investigation of more samples in one step in a very efficient way.     

Plasma Beam Discharge in Carbon Dioxide

The paper deals with the dissociation of carbon dioxide in nonequilibrium plasma of a stationary plasma-beam discharge. Experimental results of spectroscopic and probe measurements of plasma parameters are given. Moreover, a mass-spectrometric analysis of gaseous products of the chemical reactions is presented. In addition the measurement of the deposition rate of solid products by means of a quartz oscillator is described. The results show that plasma beam discharge is an effective tool for inducing plasma-chemical reactions.     

Numerical Solution of a Fluid Filtration Problem in a Fractured Medium by Using the Domain Decomposition Method

Under consideration are the numerical methods for simulation of a fluid flow in fractured porous media. The fractures are taken into account explicitly by using a discrete fracture model. The formulated single-phase filtering problem is approximated by an implicit finite element method on unstructured grids that resolve fractures at the grid level. The systems of linear algebraic equations (SLAE) are solved by the iterative methods of domain decomposition in the Krylov subspaces using the KRYLOVlibrary of parallel algorithms. The results of solving some model problem are presented. A study is conducted of the efficiency of the computational implementation for various values of contrast coefficients which significantly affect the condition number and the number of iterations required for convergence of the method.     

The spectral radius of graphs without paths and cycles of specified length

Let G be a graph with n vertices and μ(G) be the largest eigenvalue of the adjacency matrix of G. We study how large μ(G) can be when G does not contain cycles and paths of specified order. In particular, we determine the maximum spectral radius of graphs without paths of given length, and give tight bounds on the spectral radius of graphs without given even cycles. We also raise a number of open problems.     

Structure and the electronic and magnetic properties of LaTiO<Subscript>3</Subscript>

A model is proposed for the LaTiO₃ compound, which allows for the strong coupling of the lattice, orbital, and magnetic subsystems of this crystal. The interaction of the lattice with the electronic structure of the LaTiO₃ compound is described by the vibronic Hamiltonian with the constants calculated using the ab initio Hartree-Fock-Roothaan method with the inclusion of the electron correlations. It is demonstrated that a considerable contribution to the formation of the orbital structure of the LaTiO₃ compound is made by the next-nearest neighbors of the Ti³⁺ ion. The orbital-dependent superexchange interactions in LaTiO₃ are described within the Hubbard model and agree well with experiment.