Effect of thymic polypeptide factor on the cyclic nucleotide system of immunocompetent cells

Thyramine, a polypeptide factor from thymus, at wide range of concentrations increased the cAMP content in rat thymocytes. Increase in the cAMP content was less distinct in spleen lymphoid cells. Thyramine decreased the cGMP content in thymocytes; minimal nucleotide level was found within 15 min of incubation. The data obtained suggest that the rate of lymphocyte maturation is important for response of the cells to the effect of immunoregulating agents.     

Self-oscillations in an open biochemical substrate-inhibited reaction interacting with the enzyme-producing system

An open biochemical reaction with substrate inhibition is analysed under conditions of a continuous turnover of its enzyme maintained by the enzyme-producing system (EPS). In this reaction, self-oscillations of a long period may occur in addition to the resonance phenomena found in a simple biochemical reaction with the EPS. A distinctive property of this reaction is also superadaptation with which the total enzyme concentration increases as a square of the substrate influx rate.     

Significance of adrenal hormones in brain energy metabolism

Intensity of glycolysis was studied under conditions of immobilization stress and adrenalectomy as well as with administration of adrenaline and hydrocortisone. The processes of aerobic glycolysis, activity of enzymes of the tricarboxylic acid cycle and mitochondria respiratory chain, content of total, free and protein-bound glycogen, glucose-I-phosphate, glucose-6-phosphate, pyruvate, alpha-ketoglutarate, cytrate and macroergs in the brain are shown to depend on the level of adrenal hormones producing a multilateral effect on a series of energy metabolism links.     

Multiplicity of europium centers in doped stoichiometric crystals of lithium niobate

The optical spectra of europium-doped stoichiometric lithium niobate (LiNbO₃:Eu³⁺) crystals have been studied using combined excitation-luminescence spectroscopy in the range of ⁵D₀ → ⁷F₁, ⁷F₀ optical transitions. Analysis of the results shows that Eu³⁺ ions can occupy 14 energetically nonequivalent positions in the LiNbO₃ crystal lattice. This multiplicity of impurity centers is related to possible variants of the incorporation of Eu³⁺ ions into the LiNbO₃ crystal lattice and the compensation of excess charge. Energy positions of the ⁵D₀ level and the lowest sublevel of the ⁷F₁ Stark multiplet are determined for Eu³⁺ centers of all 14 types.     

Absorption spectra of bulk aluminum nitride crystals doped with Er<Superscript>3+</Superscript> ions

This Letter presents results of analysis of the absorption spectra of AlN:Er³⁺ bulk crystals. In the spectral of 370–700 nm, absorption lines responsible for intraconfiguration electron transition from the ground state ⁴I_15/2 to the excited states of Er³⁺ ions are found. Transitions to the levels of the ⁴F_9/2, ²H_11/2, and ⁴G_11/2 states at 2 K are studied in detail. The number of observed lines for these transitions fully agrees with that theoretically possible for f–f electron transitions in Er³⁺ ions found in a noncubic crystal field. The small width of the observed lines and their number indicate that erbium ions displace mostly one regular crystal position. Most probably, Er³⁺ occupies the position of Al. Energy positions of excited states for the considered transitions are determined.     

A method of combined indirect measurement for object quality parameters

A method is considered for measuring object quality parameters that can arise through indirect parameters, and in particular electrophysical signals acting on the object. Methods are given for obtaining a mathematical model for the measurement procedure and examples are quoted of the method applied with the use of spectrometric characteristics of the object. __________ Translated from Izmeritel'naya Tekhnika, No. 8, pp. 13–16, August, 2008.