Reduction of the matrix influence on analytical signal in laser-enhanced ionization spectrometry with laser sampling

The novel approach using a slope of correlation line (laser-enhanced ionization of lithium versus laser-induced plasma emission of aluminum) as analytical signal was proposed for reduction of matrix interferences in laser-enhanced ionization spectrometric determination of Li with laser sampling.     

Probe detection of charged coarsely dispersed carbon particles upon laser ablation of pyrolytic graphite

The mass distribution of charged particles from the plasma plume produced by laser ablation of pyrolytic graphite was studied by an electrostatic probe technique. The velocities of motion of the charged opposite parts of the plume double-electric layer and the potential of its internal self-consistent field were determined. Using a proposed procedure for the treatment of probe signals, the amounts of detectable positive and negative ions were evaluated. The negatively charged large carbon particles with a size of up to 10⁶ atoms were assumed to directly appear from explosive bulk effervescence and spinodal separation of the overheated carbon phase on the graphite surface.     

Laser atomic-ionization determination of caesium in flames

The laser atomic-ionization (AI) method has been developed for determination of caesium in flames. The limit of detection for caesium in pure aqueous solution is 4 pg ml . The interference of Li, Na, K, Rb, Ca and Fe with the AI signal of caesium has been investigated and explained. The analytical potential of this method has been demonstrated by determination of caesium in water samples, in the concentration range 0.1-1 ng ml .     

Crystalline carbon nitrides: thin films and bulk samples

A new method was developed for the preparation of bulk samples of crystalline carbon nitride on exposure of an amorphous nitrogen- and carbon-containing material to high temperature and ultrahigh pressure in the presence of crystallization seeds. Amorphous carbon nitride whose composition was close to C₃N₄was used as a starting material. Thin films of crystalline carbon nitrides prepared by the laser-electric discharge method were used as crystallization seeds.     

Molecular Modelling of Disease-Causing Single-Nucleotide Polymorphisms in Collagen

Abstract

The purpose of the work was to investigate at the molecular structural and energy levels the consequence of amino acid substitutions in collagen that cause systemic diseases. The data have been systematized on defects in human collagen III, and the patterns of single-nucleotide polymorphisms collected. Then molecular mechanics calculations were performed for native and mutant collagen molecule fragments. The observed energy components and structural alterations that accompany particular amino acid substitutions were used to propose an interpretation of negative consequences in terms of stability and hydration of the macromolecule.     

The Minor Recombinant Laccase Isozymes of Trametes hirsuta 072: Preparation and Properties

Moscow University Chemistry Bulletin - Laccases (EC 1.10.3.2) are multicopper polyphenol oxidases found in various organisms, in particular, in fungi. Fungal laccases are encoded by multigene...     

A review of normalization techniques in analytical atomic spectrometry with laser sampling: From single to multivariate correction

Despite many advantages of laser sampling in analytical atomic spectrometry, the signal intensity of these hyphenated methods suffers from the specific influences resulting from the laser ablation process of a sample. The problems that arise affect the accuracy and precision of analytical results. Different techniques of analytical signal normalization which improve figures-of-merit for atomic spectrometry with laser sampling are considered in this review. The characteristics and application of these approaches including the use of internal standards, single or several reference signals and multivariate correction of analytical signal are discussed.