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V F Nesterenko

Publications and source records attributed to V F Nesterenko.

17 recordsLinked to original sources
PubMed2006

Strongly nonlinear wave dynamics in a chain of polymer coated beads.

Strongly nonlinear phononic crystals were assembled from a chain of Parylene-C coated steel spheres in a polytetrafluoroethylene holder. This system exhibits strongly nonlinear properties and extends the range of materials supporting sonic-vacuum-type behavior. The combination of a high density core and a soft (low elastic modulus) coating ensures a relatively low velocity of wave propagation. The bead contact interaction caused by the deformation of the Parylene coating can be described by classical nonlinear elastic Hertz theory with an effective value of the elastic modulus equal to 15 GPa for the contact interaction. Strongly nonlinear solitary waves excited by impacts were investigated experimentally and compared to chains composed of uniform steel beads. Fracture of the polymer coating was detected under relatively large pulse amplitude.

Journal Article↗
PubMed2006

Tunability of solitary wave properties in one-dimensional strongly nonlinear phononic crystals.

One-dimensional strongly nonlinear phononic crystals were assembled from chains of PTFE (polytetrafluoroethylene) and stainless-steel spheres with gauges installed inside the beads. Trains of strongly nonlinear solitary waves were excited by impacts. A significant modification of the signal shape and an increase of solitary wave speed up to two times (at the same magnitude of dynamic contact force) were achieved through a noncontact magnetically induced precompression of the chains. The data for the PTFE based chains are presented for the first time and the data for the stainless-steel beads chains are extended into a range of maximum dynamic forces more than one order of magnitude lower than previously reported. Experimental results agreed reasonably well with the long-wave approximation and numerical calculations based on the Hertz interaction law for particles interactions.

Journal Article↗
PubMed2006

Energy trapping and shock disintegration in a composite granular medium.

We report the first experimental observation of impulse confinement and the disintegration of shock and solitary waves in one-dimensional strongly nonlinear composite granular materials. The chains consist of alternating ensembles of beads with high and low elastic moduli (more than 2 orders of magnitude difference) of different masses. The trapped energy is contained within the "softer" sections of the composite chain and is slowly released in the form of weak, separated pulses over an extended period of time. This effect is enhanced by using a specific group assembly and precompression.

Journal Article↗
PubMed2005

Anomalous wave reflection at the interface of two strongly nonlinear granular media.

Granular materials exhibit a strongly nonlinear behavior affecting the propagation of energy and information. Dynamically self-organized strongly nonlinear solitary waves are the main information carriers in granular chains. We report the first experimental observation of the dramatic change of solitary wave reflectivity from the interface of two granular media triggered by a magnetically induced precompression. It may be appropriate to name this phenomenon the "acoustic diode" effect. We explain this effect by the high gradient of particle velocity near the interface.

Colloids↗
PubMed2005

Strongly nonlinear waves in a chain of Teflon beads.

One-dimensional "sonic vacuum" type phononic crystals were assembled from a chain of polytetrafluoroethylene (PTFE,Teflon) spheres with different diameters in a Teflon holder. It was demonstrated that this polymer-based sonic vacuum, with exceptionally low elastic modulus of particles, supports propagation of strongly nonlinear solitary waves with a very low speed. These solitary waves can be described using the classical nonlinear Hertz law despite the viscoelastic nature of the polymer and high strain rate deformation of the contact area. The experimentally measured speeds of solitary waves at high amplitudes are close to the theoretically estimated values with a Young's modulus of 1.46 GPa obtained from shock wave experiments. This is significantly higher than the Young's modulus of PTFE from ultrasonic measurements. Trains of strongly nonlinear solitary waves excited by an impact were investigated experimentally and were found to be in reasonable agreement with numerical calculations based on Hertz interaction law though exhibiting a significant dissipation.

Journal Article↗
PubMed1986

[DNA-methylases from different strains of Bacillus subtilis and Bacillus natto].

DNA-methyltransferase activity has been detected in some of Bacillus subtilis and Bacillus natto strains. Two strains of Bacillus subtilis exhibited DNA-cytosine methyltransferase activity, and the strains of Bacillus natto exhibited DNA-adenine methyltransferase activity. A possible effect of DNA-methyltransferase specificity on transformation efficiency is discussed.

Bacillus↗
PubMed1985

[Effect of 5-azacytidine on E. coli cells with different DNA-methylases].

A correlation was found between the bacteriocide effect of 5-aza-C and the amount of cytosine DNA-methylases in E. coli cells. 5-Aza-C-DNA induced partial or complete inhibition of bacterial DNA-methylases with different site specificity; cytosine DNA-methylases were inhibited by the DNA more effectively than adenine DNA-methylase Eco dam. The inhibitory influence of 5-aza-C-DNA on cytosine DNA-methylases was due to the formation of stable inactive complexes between the enzyme and the non-methylating cytosine analog in the recognition sites. Cytosine DNA-methylase Eco RII formed a relatively firm bond with 5-aza-C-DNA, which could be disrupted by 1 M KCl; this disruption restores the DNA-methylase activity and the inhibiting capacity of 5-aza-C-DNA. Thus, the binding of cytosine DNA-methylase to 5-aza-C in DNA is noncovalent; the inhibition of the enzyme by 5-aza-C-DNA is reversible.

Azacitidine↗
PubMed1982

[Use of DNA-methylases as reagents for the production of isotopically labeled DNAs].

The method of incorporation of an isotopic label into DNA by means of DNA-methyltransferases (DNA-methylases) is proposed. DNA was no degraded and retained its biological activity in the DNA-methylase reaction. The specific activity of labelled DNA preparations can be increased, using the mixtures of different DNA-methylases in the enzymatic reaction. An isotopic label was incorporated into DNA, using DNA methylases M. .EcoRII, M.Eco dam and M.EcoMRE600 dcmI. An average activity of 1 microgram of labelled DNA preparations produced by S-adenosylmethionine (methyl-3H) with specific activity of 15 CU/mmol mas about 1 x 10(5) cpm.

DNA↗
PubMed1979

[Isolation and properties of DNA-cytosine-methylase I from Escherichia coli MRE 600].

DNA-cytosine-methylase I was isolated and purified to homogeneity. The yield made up to about 30% of total activity. The enzyme molecular weight as determined by centrifugation in a sucrose gradient, by gel filtration and by electrophoresis in polyacrylamide gel in the presence of sodium dodecyl sulfate was found to be 45,000. The Michaelis constant was 1,8 . 10(-6) M for SAM and 2 . 10(-4) M for DNA. DNA-cytosine-methylase I modifies phage lambda DNA in 60 sites. This modification does not protect DNA from the effects of restriction endonucleases HpaII and BsuRI. The enzyme methylates DNA in the nucleotide sequence: 5'...Pur-MC-C-G-G-Pyr...3'.

DNA (Cytosine-5-)-Methyltransferases↗