Determination of lysinoalanine by high performance liquid chromatography

This work suggests an HPLC method for qualitative and quantitative determination of N^ε(2-amino-2-carboxyethyl)-L -lysine (LAL). LAL was released from total hydrolysates of various proteins of animal origin and derivatized with dansyl chloride. The performance of two different columns, Spherisorb 3S TG and μ-Bondapack C₁₈, was compared; better resolution and quantitative response were obtained with the former. The mobile phase was a mixture of 0.01 M phosphate buffer (pH 7) and acetonitrile. Linear response and quantitative repeatability were tested for both detectors used (UV-Vis set at 254 nm; fluorimetric set at λ_ex(max) = 360 nm and λ_em(max) = 525 nm). For LAL standard the minimum detectable amount was 0.05 ng, whereas for LAL in actual samples the amount was 0.5 ng (40 μg/g of analyzed proteins). Good analytical repeatability was obtained, resulting in CV % of 4.7 and 3.8 for UV and fluorimetric detectors, respectively. LAL recovery was determined using both detectors; the values obtained were 94 % (fluorimetric) and 92 % (UV). Greater noise levels were observed with the fluorimetric detector and its higher sensitivity could not, therefore, be fully utilized. The highest amounts of LAL were found in the casein (2816 μg/g) and cooked albumin (615 μg/g) samples.     

Groups with finitely many normalizers of non-abelian subgroups

Abstract A group is called metahamiltonian if all its non-abelian subgroups are normal; it is known that locally soluble metahamiltonian groups have finite commutator subgroup. Here the structure of locally graded groups with finitely many normalizers of (infinite) non-abelian subgroups is investigated, and the above result is extended to this more general situation. Keywords: normalizer subgroup, metahamiltonian group Mathematics Subject Classification (2000): 20F24     

The Einstein-Yang-Mills equations

The interaction between gravitational and gauge fields is considered. A new characterization of the Einstein-Yang-Mills equations is given. In particular, necessary and sufficient conditions which ensure the decomposition of the total Lagrangian density are established. The emphasis is on the general covariance requirements of the basic geometrical objects involved. This leads, among other things, to a better understanding of the role played by the Bianchi identity.     

A new route to penems and carbapenems

A new ring closure by carbonyl-carbonyl reductive coupling is utilized in the synthesis of penem and carbapenem nuclei.     

Ordinary Papers

This paper deals with the systems of algebraic equations arising in the application of implicit Runge-Kutta methods.Equivalent conditions under which three wide classes of differential equations have unique solutions are presented. In addition, sufficient conditions for their existence are given.     

Polarization of Lidar Returns from Water Clouds: Calculations and Laboratory Scaled Measurements

The main features of a Monte Carlo code developed to deal with polarization of lidar returns from water clouds in multiple scattering regime are described. The paper presents an example of results pertaining to a stratified cloud structure, and a series of comparisons of calculation results with measurements carried out in the laboratory. For double scattering a comparison of Monte Carlo results with those of an analytical formula is also given.Presented at the 7th International Workshop on Multiple Scattering Lidar/Light Experiments (MUSCLE7), July 21–23 1994, Chiba, Japan.     

A study of the enolization of some alkyl ketones in lyomesophases formed by alkylammonium surfactants

The kinetics of enolization of acetone, 3-pentanone, and 6-undecanone have been studied in lyotropic systems in the isotropic, nematic, and lamellar phases. The data, analysed in terms of spontaneous and acid-catalyzed rate constants, do not show any relevant influence of the physical nature of the phase. Effects are instead observed in relation to the length of the alkyl chains of the ketones and the type of the amphiphilic molecule. 6-undecanone has a surprising effect in stabilizing ordered mesophases.