The influence of physical-chemical characteristics of surface modified copper nanoparticles on E. coli cell population growth suppression and on electrostatic properties of their membranes
The biological activity of copper nanoparticles, able to suppress growth of E. coli cells population under contact interactions, was explored. Three types of samples with oxide layers of various sizes, thickness and composition were used in experiments. It was found out, that an increase in electron density on the external membrane of E. coli correlated with copper nanoparticles suppression capability and with lower activation energy of electron transfer on bacteria. The analysis of experimental data helps to correct conditions for obtaining nanoparticles with certain properties of their surface oxide layers. The character of temperature dependence of electron density reveals the electron type of conductivity in contact area of E. coli and nano-particles. These results help to find approach to understanding the nature of toxic influence of copper nano-particles on E. coli cells under contact interaction.
Influence of a finely dispersed suspension based on a metal/carbon nanocomposite of copper on growth processes and seeds infection of spring wheat
The article presents the results of laboratory studies on the treatment of spring wheat seeds of the Svecha variety with a fine suspension based on a metal/carbon nanocomposite of copper (MeC NC Cu). The aim of the research is to identify the fungicidal action and stimulate the growth processes of plants at the initial stage of organogenesis. The experimental results showed that the effect of copper nanocomposite on plants is ambiguous and in some cases contradictory. This nanomaterial at a concentration of 0.1% had a toxic effect on the seeds of Triticum aestivum. The drug at a concentration of 0.005% (by 15.7%) had a weak stimulating, but insignificant, effect on root development. It was revealed that an increase in the concentration of MeC NC Cu has an inhibitory effect on plants: the immune system weakens and the resistance to pathogens of seed infection decreases. Development of Bipolaris sorokiniana Syn. increases by 2.90-3.31%, Alternaria sp. - by 1.94%. With an increase in the concentration of NC to 1.00%, the indicators deteriorate in comparison with the control to 3.06%. Infection of seeds with a fungus of the genus Fusarium was observed in the following variants: MeC NC Cu 0.05% by 54.5%, MeC NC Cu 1.0% by 6.90% with the least significant difference (95%) 1.36. Other fungi are noted in descending order; the degree of damage varied from 4.65% to 7.83% with an increase in the concentration of MeC NC Cu (the least significant difference (95%) = 0.67).
Suppressed Light Emission of the Reaction Zone in Detonation
THE detonation of high explosives in water can be photographed with an open camera and a flash light as the explosive gases do not emit light. The method has been used1 to investigate the spread of shock waves and explosive gases, and to investigate the initiation by shock waves2. We have found that it can be used also in certain gases such as butane and propane. The method is not suitable, on the other hand, for explosives with two levels of detonation velocity in the case of low velocity. A great part of the reaction then occurs after the reaction zone has passed and the expanding explosive gases are very luminous even in water.