High-efficiency bragg gratings in photothermorefractive glass.

Photosensitive silicate glasses doped with silver, cerium, fluorine, and bromine were fabricated at the Center for Research and Education in Optics and Lasers. Bragg diffractive gratings were recorded in the volume of these glasses with a photothermorefractive process (exposure to UV radiation of a He-Cd laser at 325 nm is followed by thermal development at 520 degrees C). Absolute diffraction efficiency of as much as 93% was observed for 1-mm-thick gratings with spatial frequencies up to 2500 mm(-1). No decreasing of diffraction efficiency was detected at low spatial frequencies. Original glasses were transparent (absorption coefficient less than 1 cm(-1)) from 350 to 4100 nm. Induced losses in exposed and developed glass decreased from 0.3 to 0.03 cm(-1) between 400 and 700 nm, respectively, and did not exceed 0.01-0.02 cm(-1) in the IR region from 700 to 2500 nm. Additional losses caused by parasitic structures recorded in the photosensitive medium were studied.

[Changes in the function and energy metabolism of the myocardium in experimental diabetes mellitus in dogs]. / Izmeneniia funktsii i énergeticheskogo obmena miokarda pri éksperimental'nom sakharnom diabete u sobak.

Coronary arteries, coronary sinus, heart cavities, and great vessels were catheterized in anesthetized dogs with alloxan diabetes. Cardiac contractility, coronary and systemic circulation, myocardial energy metabolism and acid-base balance were studied. It was shown that the alterations of the cardiac function occurred in experimental dogs with severe diabetes mellitus. They consisted of a decrease in cardiac and working outputs, ejection period, maximum velocity of the left ventricular contractions and an increase in the projection period. These dysfunctions were caused by the alterations of the myocardial energy metabolism and systemic changes in the acid-base balance.

[Nature of the melipramine inhibition of the K+-n-nitrophenyl phosphatase activity of a synaptosomal fraction]. / Kharakter ingibirovaniia melipraminom K+-n-nitrofenilfosfataznoi aktivnosti sinaptosomnoi fraktsii.

The influence of antidepressant melipramine (imipramine) on the K+-paranitrophenyl-phosphatase (K+-n-NFP-ase) activity of the synaptosomal fraction in the bull's brain cortex, treated with sodium iodide, was studied in in vitro experiments. Melipramine (5.10(-5)--10(-3)M) is shown to inhibit the K+-n-NFP-ase activity, competing with potassium ions. With pH changing from acid and neutral to alkaline values the inhibitory action of melipramine gains in intensity, whereas the protective effect of potassium ions declines. It is suggested that one of the mechanisms responsible for the inhibition of the K+-p-NFP-ase activity by melipramine is interaction of the inhibitor in the anionic sections of the enzyme complex.

[Kinetic studies of melipramine inhibition of Na+, K+-ATPase activity in the synaptosomal fraction of the brain]. / Kinetychni doslidzhennia hal'muvannia melipraminom NA+,K+-ATF-aznoï sktyvnosti synaptosomnoï fraktsii mozku

The effect of antidepressant melipramine (imipramine) on the Na+, K+-ATPase activity was studied in the brain synaptosomes as dependent on the sodium and potassium ions concentration and pH of the incubation medium. Melipramine in concentrations of 0.05-1.0 mM is shown to inhibit the Na+, K+-ATPase activity. Under pH 7.4 monovalent cations prevent the inhibitory action of melipramine, changing the kinetic of the interaction between melipramine and the enzyme preparation. When changing pH from 7.4 to 8.2 the preventional action of the ions decreases, and the inhibitory action of melipramine on the Na+, K+-ATPase activity increases. Possible mechanisms of the melipramine interaction with Na+, K+-ATPase system are discussed.