Formation of nonlinear holographic images in powerful laser systems.

The formation of nonlinear holographic images behind a multislab amplifier is studied. The analytical expressions describing magnitudes and locations of intensity maxima depending on the corresponding image number are derived. Comparison with numerical calculations results is given.

Risky intensity peaks resulting from nonlinear holographic imaging.

A study of the maximal intensity peaks due to nonlinear holographic images of obstacles such as obscurations or phase defects in a high-power laser system is presented. It is shown that the interference of the high-power plane wave and the converging image wave results in the formation of intensity maximums in the vicinity of the image plane, the values of which significantly exceed the intensity in the image plane itself. For round obstacles, analytical expressions that describe magnitudes and locations of the maxima depending on the radius and the type of obstacle are given.

[Short peptide fragments with antiulcer activity from a collagen hydrolysate].

A peptide acidic hydrolysate of collagen (PHC) was obtained under conditions (4 N HCl) ensuring the predominant formation of short peptides, glyprolines. They were separated and their antiulcer activity was studied. Thirty individual peptides with molecular masses of 174-420 amu were isolated from the PHC by HPLC.

200 TW 45 fs laser based on optical parametric chirped pulse amplification.

200 TW peak power has been achieved experimentally using a Cr:forsterite master oscillator at 1250 nm, a stretcher, three optical parametrical amplifiers based on KD*P (DKDP) crystals providing 14.5 J energy in the chirped pulse at 910 nm central wavelength, and a vacuum compressor. The final parametrical amplifier and the compressor are described in detail.

Study of secondary specificity of enteropeptidase in comparison with trypsin.

A comparative study of secondary specificities of enteropeptidase and trypsin was performed using peptide substrates with general formula A-(Asp/Glu)n-Lys(Arg)-(downward arrow)-B, where n = 1-4. This was the first study to demonstrate that, similar to other serine proteases, enteropeptidase has an extended secondary binding site interacting with 6-7 amino acid residues surrounding the peptide bond to be hydrolyzed. However, in the case of typical enteropeptidase substrates containing four negatively charged Asp/Glu residues at positions P2-P5, electrostatic interaction between these residues and the secondary site Lys99 of the enteropeptidase light chain is the main factor that determines hydrolysis efficiency.