Luteolin glucosides fromFerula varia

Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 891475. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 679–680, September–October, 1994.     

Liquid chromatography and mass spectrometry determination of aromatic amines in hydrolysed urine from workers exposed to thermal degradation products of polyurethane

Chromatographia - An LC-MS method is described for the determination of 4,4′-MDA (4,4′-methylene dianiline) in hydrolysed urine as a biomarker for exposure to 4,4′-MDI...     

Limits of resolution and speed of analysis in linear chromatography with and without focusing

Chromatographia - Previously [11], the theoretical limit ofresolution in one class of chromatographic conditions was found and its proof was briefly outlined. Here, the theoretical limits...     

End unit effect on the Tg of differentiated series of perfluoro-poly (oxymethylene-co-oxyethylene) oligomers

Twelve series of linear oligomers of four different degrees of polymerization (x_n = 8.77−41.55), having a common perfluorinated random copolymeric chain as molecular body and two equal foreign end units of one of the types listed in Table 1, have been synthesized by derivatization of base samples of one of them having a diolic---CH₂OH functionality. The glass transition temperature T_g of all the series was measured and thus examined as a function of x_n. A clear end unit effect is observed, dominantly determined in every series by chemical nature and structure of the end units, quantitatively expressed at any x_n by different positive or negative T_g deviations from the common asymptotic T_g∞ value. The results are also discussed in terms of copolymer end effect and of relation between T_g and end copolymeric composition.     

Theory of relaxed density matrices: Application to second-order response properties

The evaluation of second derivatives of the electronic energy for nonvariational wave functions using an energy functional is discussed. It is shown that, in certain cases, the formation of the first-order relaxed density matrix leads to an efficient algorithm for the calculation of second-order response properties. Detailed formulas are given for second-order Møller–Plesset perturbation theory. © 1994 John Wiley & Sons, Inc.     

Density functionals for exchange and correlation energies: Exact conditions and comparison of approximations

A set of exact conditions is compiled for the purpose of developing and testing approximations for the exchange-correlation energy as a functional of the electron density. Special emphasis is placed upon recently developed density-scaling relationships. Commonly used generalized gradient approximations are compared against several of these conditions. A direct tabular comparison of these functionals (not of calculated properties) with one another is also made. © 1994 John Wiley & Sons, Inc.     

Dynamic study of gated saturable absorbers

The capability of gated saturable absorbers for single-pulse selection is studied theoretically using the classical space-time-dependent rate-equation model. The dynamics of operation is followed experimentally by the well-known pump—probe technique. Comparing the theoretical and experimental results, it is found that gated saturable absorbers can efficiently be used for pulse forming and pulse selection of pulses longer than picosecond.     

Application of differential electrolytic potentiometry for detection in flow injection analysis

The applicability of differential electrolytic potentiometry as a detection system in flow injection analysis is investigated. A computer-controlled injector which delivers precise volumes of sample solutions in a reproducible manner was developed. Conditions such as current density employed, the concentrations of the solutions used and the flow rate were optimized. Chloride in water was determined by means of this system. The relation between chloride concentration and the measured signal was found to be Nernstian for solutions of concentrations above 6 μg ml⁻¹ chloride. For solutions below this concentration, the relation is linear.