Distribution of matter in the current-carrying plasma and dense core of the discharge channel formed upon electrical wire explosion

Distribution of matter in the discharge channel formed upon a nanosecond electrical explosion of a single wire in air and vacuum was studied experimentally. Simultaneous use of optical, UV, and X-ray diagnostics made it possible to distinguish qualitatively different regions of the discharge channel, such as the current-carrying layers and the region occupied by a weakly conducting cold plasma. Several series of experiments with 25-μm-diameter 12-mm-long wires made of different materials were performed. The charging voltage and the current amplitude were varied in the ranges of U ₀ = 10–20 kV and I _max ∼ 5–10 kA, respectively. Explosion regimes with a current pause and with and without current interruption, as well as with wire preheating in air and vacuum, were studied. Shadow and schlieren images of the discharge channel were obtained using optical probing at the second harmonic of a YAG: Nd⁺³ laser (λ = 0.532 μm, τ ∼ 10 ns). In the experiments carried out in vacuum, X-ray images of the discharge channel were also obtained using an X-pinch as a point source of probing radiation and UV images were recorded using a four-frame MCP camera.     

Modification of the process of resorption of alpha-emitting nuclides from the gastrointestinal tract depending upon the properties of administered compounds and the physiological state of rats

In experiments on rats a study was made of resorption from the gastrointestinal tract of simple salts, complex compounds and "biologically incorporated" forms of transuranium nuclides, the influence of age, pregnancy and chemically active substances (for instance, trivalent iron and ethyl alcohol) on this process.     

Mass exchange conditions in penicillin biosynthesis in an industrial fermenter with aerodynamic foam suppressor

The mass exchange characteristics of 50 m3 industrial fermentors with aerodynamic foam suppression and the effect of the specific power input on biosynthesis of penicillin were studied. A change in the specific power input from 1.3 to 1.9 kW/m3 had no effect on the level of the antibiotic accumulation when the medium with 8 per cent of lactose was used. An increase in the aeration rate from 1 to 1.2 m3/m3 X min provided a 1.1-fold increase in the penicillin activity of the fermentation broth. The use of the device for aerodynamic foam suppression with a system of automatic control of the partial pressure of dissolved carbon dioxide allowed decreasing 1.22-fold the oil use and increasing the process productivity by 10 per cent.     

Participation of agouti-related peptide in the regulation of the wakefulness-sleep cycle

Agouti-related peptide is expressed in the hypothalamic neurons in humans and animals. Immunohistochemical studies in Wistar rats shows significant changes in the optical density of agouti-related peptide in the neurons of the arcuate hypothalamic nucleus, as well as in their processes in the hypothalamus and nucleus accumbens after 6 h of sleep deprivation (an increase) and after 2 h of post-deprivative sleep (a decrease). Comparison of these findings with the earlier results shows the opposite trends in the changes in the optical density of agouti-related peptide and the speed of the limiting enzyme of dopamine synthesis, tyrosine hydroxylase, in the hypothalamus and in the striatonigral system. An increase in the agouti-related peptide level was accompanied by a decrease in tyrosine hydroxylase, while a decrease in agouti-related peptide, on the contrary, was accompanied by an increase in the tyrosine hydroxylase activity. Our data show the role played by agouti-related peptide as a modulator of the functional activity of the dopaminergic brain neurons. The interrelation between various functions of the body, such as food behavior, sleep, and stress, is considered to be mediated by the participation of the same neurotransmitter systems in their regulation.     

Stress reactions of Scots pine trees to injuring by ground fire

Controlled burning has been carried out to stimulate moderate ground fire in the Scots pine (Pinus sуlvestris L.) stand (age class I) in the Krasnoyarsk forest steppe at the beginning of the growing season. The structure of annual rings and trophic supply, as well as the cambial zone antioxidant system condition and the content of photosynthetic pigments in the needles of dominant and suppressed trees in the experimental and control plots, were studied 3 h, 5 days, and 2.5 months after the fire. The fire narrowed the annual ring width, since the number and size of early and late tracheids decreased. The primary reaction to pyrogenic heat shock (sharp reduction of chlorophyll content in needles and manifestation of oxidative stress in the stem cambial zone) was an elevated level of hydrogen peroxide and activity of most antioxidant enzymes and a reduction in the nonstructural carbohydrates pool. Restoration of the cambium function after the fire was promoted by an increased activity of amylase, invertase, and peroxidase.