Damping properties of porous titanium and pseudoalloys based on it

Conclusions The vibration-absorbing capacity of titanium increases with an increase in porosity, which is the resuit of the higher stress concentration at the surface of pores causing a higher level of microplastic deformation in the local areas of the skeleton. The size of the titanium powder fraction has a significant influence on the vibration-absorbing properties of the investigated materials. An increase in the titanium powder size causes easing of the conditions for occurrence of local deformations in the larger microvolumes.The basic mechanisms of dissipation of energy in the investigated pseudoalloys are microplastic deformation caused by stress concentration close to the pores filled with the low-melting constituent, microplastic deformation of the low-melting soft phase, and friction between the titanium skeleton and the low-melting constituent.The investigation of the damping capacity of porous titanium and pseudoalloys based on it showed the possibility of their use as constructional materials for the production of machine parts subjected to dynamic action.Translated from Poroshkovaya Metaliurgiya, No. 5(269), pp. 81–85, May, 1985.     

Actual problems encountered in the 50-year development of water management and their coverage by the journal

Conclusions During the journal's 50-yr existence, it has shed light on a broad circle of problems associated with water management. As it developed and new problems were put forth by construction practice, the subject matter of papers was expanded, and many questions received a more profound and comprehensive coverage.In the modern stage of the development of our country's water-conservation construction, the journal should, together with traditional problems, focus more attention on questions of territorial flow redistribution, measures for protecting water resources from depletion and pollution, and measures for increasing the effectiveness of both reservoirs and natural water bodies due to their engineering layout; in all cases, the ecological and economic aspects of problems associated with water management should receive broader coverage.Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 11, pp. 36–39, November, 1981.     

The Role of Phospholipase Activity of Peroxiredoxin 6 in Its Transmembrane Transport and Protective Properties

Peroxiredoxin 6 (Prdx6) is a multifunctional eukaryotic antioxidant enzyme. Mammalian Prdx6 possesses peroxidase activity against a wide range of organic and inorganic hydroperoxides, as well as exhibits phospholipase A2 (aiPLA2) activity, which plays an important role in the reduction of oxidized phospholipids and cell membrane remodeling. Exogenous Prdx6 has recently been shown to be able to penetrate inside the cell. We hypothesized that this entry may be due to the phospholipase activity of Prdx6. Experiments using exogenous Prdx6 in three cell lines (3T3, A549, RAW 264.7) demonstrated that it is the phospholipase activity that promotes its penetration into the cell. Overoxidation of Prdx6 led to a suppression of the peroxidase activity and a 3-to-4-fold growth of aiPLA2, which enhanced the efficiency of its transmembrane transport into the cells by up to 15 times. A mutant form of Prdx6-S32A with an inactivated phospholipase center turned out to be unable to enter the cells in both the reduced and oxidized state of the peroxidase active center. Previously, we have shown that exogenous Prdx6 has a significant radioprotective action. However, the role of phospholipase activity in the radioprotective effects of Prdx6 remained unstudied. Trials with the mutant Prdx6-S32A form, with the use of a total irradiation model in mice, showed a nearly 50% reduction of the radioprotective effect upon aiPLA2 loss. Such a significant decrease in the radioprotective action may be due to the inability of Prdx6-S32A to penetrate animal cells, which prevents its reduction by the natural intracellular reducing agent glutathione S-transferase (πGST) and lowers the efficiency of elimination of peroxides formed from the effect of ionizing radiation. Thus, phospholipase activity may play an important role in the reduction of oxidized Prdx6 and manifestation of its antioxidant properties.