Synthesis of the nitrogen-fixing enzyme system in oligonitrophilic bacteria

Oligonitrophilic bacteria were cultivated on a medium containing only 2.5--10.0 mg/litre of nitrogen compounds. They assimilated elementary nitrogen only after utilization of these nitrogen compounds during growth and formation of nitrogen-fixing enzyme system. Their cells grown on a medium containing high concentrations of bound nitrogen did not fix nitrogen during further incubation in the atmosphere of 15N; therefore, the enzymes involved in nitrogen fixation were induced. These organisms are characterized by diauxia during their growth on media containing "start" doses of nitrogen. Enzymes catalysing nitrogen fixation in azotobacter are also induced. But, contrary to oligonitrophilic bacteria, the azotobacter does not require nitrogen compounds in the medium in order to adapt to molecular nitrogen, and its growth curve is not of a biphasal character. These data and the evidence of other authors suggest that all nitrogen-fixing microorganisms are characterized by the induced, not constitutive, enzymes involved in reduction of molecular nitrogen.     

Biogenesis of cellulolytic enzymes by Trichoderma ligorum on media with "inductor"

Identical distribution of C2- and Cx-cellulase activities of enzyme complexes produced by Trichoderma lignorum on a medium with lactose, a soluble "inductor", and on a medium with cellulose was found by means of disc elestrophoresis in polyacrylamide gel. The maximum rate of synthesis of cellulases on the medium with lactose was registered during the highest deceleration, and even complete cessation, of the fungal growth. During this phase, only one electrophoretically homogeneous cellulase component with Rf of 0.44 possessing all types of the cellulase activity is present in the cultural broth. In the course of growth of the fungus on cellulose after 48 hours, also only one electrophoretically homogeneous component with Rf of 0.44 was found in the cultural broth when the rate of the substrate degradation was highest. The appearance of minor protein components with the activity of cellulase at later stages of cultivation after cessation of the fungal growth is supposed to be caused by modification of the main cellulase component with Rf of 0.44 by the growth medium.     

Influence of the dentate fascia on the sensory responses of neurons in hippocampal field CA3

In experiments with unanaesthetized rabbits the influences of electric stimulation of the dentate fascia (DF) on the extracellularly recorded spontaneous and evoked activity of the CA3 neurones were investigated. Stimulation of a fixed locus in the DF during recording in the CA3 by a microelectrode, shifted along the longitudinal axis of the hippocampus, supported the notion of the topical, "segmental" organization of connections between the DF and CA3. A relatively narrow "active zone" (approximately 700 nm) appeared in the CA3 during the threshold DF stimulation: it was bordered by zones with predominantly inhibitory responses to stimulation. The CA3 neurones in the "active zone" rapidly lost their reactivity to sensory stimuli. In the "inhibitory" and "zero" zones the normal level of reactivity to sensory stimuli was preserved.     

Changes in Structure and Physicochemical Properties of Spark Coatings Based on TiN and TiB2 after Treatment with Concentrated Solar Radiation

Studies have been made on the structure and properties of spark coatings made of TiN and TiB₂ on steel U8 after treatment with concentrated solar radiation. It is found that the absorption capacity of the steel raised by a factor 2–3. The concentrated radiation reduces the coefficient of friction of the spark coatings made of TiN and TiB₂ by a factor 1.4, while the wear rate is reduced by a factor 1.6–2 by comparison with the untreated material. __________ Translated from Poroshkovaya Metallurgiya, Nos. 7–8(444), pp. 64–69, July–August, 2005.     

Prospects for Consteel technology in Russia

The development of the Consteel process is briefly analyzed. Foreign experience with the Consteel system and its derivatives (Faststeel and Consteel Evolution) is discussed. Its introduction in Russia is expedient for the production of high-quality steel.     

Polyaniline–13X zeolite composite‐supported platinum electrocatalysts for direct methanol fuel cell applications

We successfully synthesized 13X zeolite using a hydrothermal method. Then, composites of polyaniline (PANI) with 13X zeolite and PANI–13X with platinum were prepared by chemical oxidative polymerization and chemical reduction, respectively. Field emission scanning electron microscopy, X‐ray diffraction, Raman spectroscopy and Brunauer–Emmett–Teller techniques were used to characterize the PANI–Pt and PANI–Pt–13X composites. Further, the electrocatalytic activity towards methanol oxidation of the synthesized catalysts was explored using cyclic voltammetry in 1 mol L^?1 CH₃OH + 0.5 mol L^?1 H₂SO₄ solution. From the obtained results, PANI–Pt–13X shows superior performance compared to PANI–Pt towards methanol oxidation and electrical conductivity. Hence, the 13X zeolite‐incorporated PANI–Pt composite could be an efficient catalyst for direct methanol fuel cell applications. © 2019 Society of Chemical Industry     

Operation mode of the proton injector in the linac of the Institute for Nuclear Research with a 100-Hz pulse repetition rate

Results of the analysis and upgrading of the high-voltage pulse generator circuit in the proton injector for operation with a 100-Hz pulse repetition rate are presented.     

The thermal effect on magnetic properties of iron-containing coatings formed on titanium by plasma-electrolytic oxidation

The effect of annealing in air at T _an temperature up to 800°C on the magnetic characteristics, elemental and phase composition, and surface morphology of iron-containing oxide coatings on titanium is studied. Annealing at T _an ?? 500°C does not seem to affect the composition and morphology of coatings. The coercive force (H _c ) of specimens equals 70 Oe at room temperature and 256 Oe at 2 K. Upon annealing at 700 or 800°C, the H _c value decreases to 13 Oe. The change in the magnetic characteristics correlates with the crystallization of a number of iron and titanium phosphates, the redistribution of elements in the coatings and pores, and the surface formation of microcrystals and whiskers.     

Gravitation theory with a Dirac scalar field in the exterior form formalism and the cosmological constant problem

As a consequence of the Poincare-Weyl gauge theory of gravity, the space-time possesses the geometric structure of Cartan-Weyl CW ₄ space with curvature and torsion 2-forms and a Weyltype nonmetricity 1-form. The Dirac field ??(x) appears as an essential additional geometric component with respect to the metric tensor. The conformal theory of gravity coupled with ??(x) in the exterior form formalism is considered. At an early stage of the universe evolution, we consider these field equations for the spatially flat FRWmetric, assuming the densities of ordinarymatter and dark matter to be very small. Then the field equations can be expressed in terms of the metric tensor and ??(t) only and have an exponentially diminishing solution for ??(t), which can explain an exponential decrease of dark energy (the energy of physical vacuum) as a function of time as a consequence of field dynamics in the ultra-early Universe.