Loading capacities of monolithic capillary columns in gas chromatography

The loading capacities of monolithic capillary columns based on silica gel and divinylbenzene are studied for two carrier gases, CO₂ and N₂. It is shown that the efficiency of the column is more sensitive to the overload of the column than the retention time of the sorbate is, especially for the CO₂ carrier gas. It is established that the loading capacity of a monolithic column based on silica gel decreases significantly in going from N₂ to CO₂. For columns based on divinylbenzene, the loading capacity is found to be virtually the same for both carrier gases. For monolithic columns, the loading capacity per one meter of column length is found to be 10 and more times higher than that for a standard open capillary column.     

Shpol'skii spectrometry, a distinct method in environmental analysis

Whereas common fluorescence and phosphorescence spectra of organic molecules in solutions show little details, Shpol'skii spectra exhibit completely resolved vibronic transitions, enabling the analytical distinction between isomeric compounds. In a simplified qualification, the Shpol'skii technique combines the sensitivity inherent to luminescence spectroscopy with the selectivity of infrared spectra. There are however two main limitations as far as its applicability is concerned: (i) cryogenic temperature conditions are required and (ii) the analytes should be compatible with the solvent matrix, typically an-alkane.The present paper is focused on the potential and achievements of Shpol'skii spectrometry in environmental analysis. After a discussion of the fundamental aspects of spectral line-broadenings and the approaches to accomplish high-resolution, special attention is paid to experimental and instrumental aspects. Recent instrumental developments have made Shpol'skii spectroscopy not only attractive for qualitative but also for quantitative purposes.The main part of the review is devoted to recent applications, for instance the determination of parent polycyclic aromatic hydrocarbons (PAHs) in complex environmental samples as crude oils, sediments, soils and biota. The special features of large PAHs, i.e. PAHs with seven or more hexagonal aromatic rings are considered separately. The analysis of PAH-metabolites in samples like fish bile and human urine is extensively discussed. Subsequently the applicability of Shpol'skii spectroscopy to both in-ring and atring substituted polycyclic aromatics is concerned, including amino- and nitro-substituted PAHs and nitrogen-, oxygen- and sulphur-heterocyclic compounds. The review ends with an interesting new development i.e. the Shpol'skii spectra of fullerenes, the soccerball and rugbyball shaped molecules C₆₀ and C₇₀, compounds receiving wide attention in physics and chemistry.     

State of atoms of the transition group elements in dilute solid solutions based on LiMO2 (M = Sc, Ga, Al): II. Magnetic characteristics of nickel atoms in LiNi x Sc1 ? x O2 solid solutions

The state of nickel atoms in LiNi _x Sc_{1 − x} O₂ solid solutions was studied. The anomalous magnetic characteristics can be accounted for only by the presence of dilution-resistant clusters containing Ni(III) in two states: high- and low-spin. Original Russian Text ? A.A. Selyutin, N.P. Bobrysheva, N.V. Chezhina, A.V. Shchukarev, A.O. Kozin, 2007, published in Zhurnal Obshchei Khimii, 2007, Vol. 77, No. 10, pp. 1608–1612. For communication I, see [1].     

Phase diagram of the Pr–Mn–O system in composition–temperature–oxygen pressure coordinates

The phase relations in the Pr–Mn–O system were studied by the static method at lowered oxygen pressure in combination with thermal analysis and high-temperature X-ray diffraction. The equilibrium oxygen pressure in dissociation of PrMn₂O₅ and PrMnO₃ was measured, and the thermodynamic characteristics of formation of these compounds from elements were calculated. The Р–Т–х phase diagram of the Pr–Mn–O system was constructed in the “composition–oxygen pressure–temperature” coordinates.     

Spectra and structure for Bi0-BiCl3-Li,K/Cl

Raman-scattering, electronic-absorption, and ESR spectra have been used to determine the states of bismuth and the structures of the compounds formed in molten chloride systems; it is found that BiCl₄ ^– with T_d symmetry are formed in BiCl₃-Li, K/Cl_eu melts, while a Bi⁰-BiCl₃-Li, K/Cl_eu melt produces the BiCl₄ ^– BiCl₃ + Cl^–; BiCl₃ + Bi⁰ Bi₂Cl₃ equilibria with the formation of Cl^– the quasitetrahedral ion in the second stage, which has a metal-bond and a single unpaired electron.Institute for General and Inorganic Chemistry, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 27, No. 3, pp. 311–315, May–June, 1991. Original article submitted September 12, 1988.     

Stress-strain state of ice cover during aircraft takeoff and landing

We consider the linear unsteady motion of an IL-76TD aircraft on ice. Water is treated as an ideal incompressible liquid, and the liquid motion is considered potential. Ice cover is modeled by an initially unstressed uniform isotropic elastic plate, and the load exerted by the aircraft on the ice cover with consideration of the wing lift is modeled by regions of distributed pressure of variable intensity, arranged under the aircraft landing gear. The effect of the thickness and elastic modulus of the ice plate, takeoff and landing regimes on stress-strain state of the ice cover used as a runway.     

Nuclear orientation and spin-lattice relaxation in Pd-Fe-Co alloys

Hyperfine field on⁵⁷Co nuclei in the system Pd-Fe-Co has been studied by very low temperature nuclear orientation technique. Low temperature spin-lattice relaxation was measured on the same set of samples by thermal cycling method. The Co hyperfine field and Korringa constant is studied in dependence on external magnetic field and on the constitution of the sample.     

Ro-vibrational spectra of C2H2 based on variational nuclear motion calculations

A published ab initio-based potential energy surface and newly constructed dipole moment surface of acetylene have been used to compute vibrational band intensities. The line intensity calculations employed the variational nuclear motion code WAVR4 for computation of wave functions and energy levels, and a newly developed code DIPOLE4 for computation of dipole transitions. Owing to the high computational cost of J > 0 transitions using direct variational methods only J = 0 and J = 1 states and transitions have been computed variationally. The intensities of J > 1 transitions were extrapolated from J = 0 and J = 1 using Hönl–London coefficients. The resulting effective rotational constants B and transition intensities are compared with experimental data for the (3ν₄ + ν₅) combination band, the ν₃ and the ν₅ fundamental band. The prospects of using this procedure for extensive calculations of a hot line list, important for cool stars and extrasolar planets are discussed.