The Influence of Silicon Dioxide on the Stability of the Phase Composition and Mechanical Properties of Alumina-Toughened Zirconia-Based Ceramics

Technical Physics - The influence of SiO2 impurity (with a concentration varying from 0 to 10 mol %) on the stability of tetragonal ZrO2 (t-ZrO2) and on a set of micro- and macromechanical...     

Effect of the grain size on the macroscopic response of aluminum to shock loading

Shock tests of two lots of a 1420 aluminum-lithium alloy are performed. The mean grain size is 24 μm in the first lot and 1.6 μm in the second lot obtained by the method of equal-channel angular pressing. Two characteristics of dynamic strength of the material were determined in experiments on the high-velocity impact of flat samples: threshold of dynamic stability with respect to compression on the fore front of the compression pulse and spall strength of the material. The materials of both types have an identical threshold of dynamic stability with respect to compression, whereas the spall strength of the microcrystalline alloy is 20% greater than the spall strength of the polycrystalline alloy. The reason is the consumption of energy on structure formation in the coarse-grain material in passing to a larger-scale structural level (in the case with a fine-grain material, such a structure is available in the initial state). The experiments reveal the presence of a second plastic front whose amplitude is approximately 10% of the first plastic front. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 48, No. 6, pp. 135–146, November–December, 2007.     

Inhibition of acid phospholipase A1 activity by the complex of tris(2-hydroxyethyl)amine with zinc bis(2-methylphenoxyacetate)

Russian Chemical Bulletin - Studies in the atherosclerosis model in rabbits showed that the complex of tris(2-hydroxyethyl)amine with zinc bis(2-methylphenoxyacetate) (zincatrane) modulates lipid...     

Complex of tris(2-hydroxyethyl)amine with zinc bis[(2-methylphenoxy)acetate] as an aortic cholesterol esterase inhibitor in the experiment

The intramuscular administration of the complex of tris(2-hydroxyethyl)amine with zinc bis[(2-methylphenoxy)acetate] (Zitrimin), as an aqueous solution in a dose of 10 mg (kg of animal weight)^?1 for 2 months decreases activity of lysosomal lipolytic hydrolase (EC 3.1.1), cholesterol esterase (EC 3.1.1.13). Hence, the previously unknown feature of Zitrimin, that is, the ability to inhibit cholesterol esterase, attests to both structural and functional disorders of subcellular structures during development of atherosclerosis. The agents active towards such reactions can be useful in this case. Owing to the new properties, Zitrimin can be used to increase the vascular system stability to cholesterol during the atherosclerotic process. This expands the scope of applicability of this compound and gives prospects for development of new Zitrimin-based drugs for preventing the atherosclerotic vascular changes.

     

Complex of tris(2-hydroxyethyl)amine with zinc bis(2-methylphenoxyacetate) as an inhibitor of the acid lipase of the aortic intima

The previously unknown ability of Zitrimin, the complex of tris(2-hydroxyethyl)amine with zinc(ii) bis(2-methylphenoxyacetate), to affect the activity of acid lipase of the aortic intima was studied. Daily administration of an aqueous solution of the tris(2-hydroxyethyl)amine complex with zinc bis(2-methylphenoxyacetate) in a dose of 10 mg kg^?1 for 3 months to rabbilts with experimental atherosclerosis was found to decrease the cholesterol and total lipid levels in the aortic tissue and to decrease the degree of aortic damage with atherosclerotic plaques. According to the results of enzymatic analysis, development of atherosclerosis is accompanied by 68% increase in the activity of acid lipase in the intima of the aorta compared to the control.

     

Complex of tris(2-hydroxyethyl)amine and zinc bis(2-methylphenoxyacetate) as inhibitor of acid cholesterol esterase synthesis in blood platelets and mononuclear cells

Russian Chemical Bulletin - Application of tris(2-hydroxyethyl)amine and zinc bis(2-methylphenoxyacetate) complex (zincatrane) in experimental atherosclerosis in rabbits leads to decrease in the...     

Strength Properties of Zirconium Ceramics with Silica Additives Hardened with Alumina

Physics of the Solid State - The effect of Al2O3 and SiO2 admixtures on strength properties of calcia-stabilized zirconia ceramics is studied. Optimal ratios of the components of CaO–ZrO2 +...     

Shock-induced phase transformation and vortex instabilities in shock loaded titanium alloys

Spall-tests of four kinds of high-strength titanium alloys (VT-6, VT-14, VT-20 and VT-23) have been performed by using a two-channel velocity interferometer for recording free surface velocity profiles and a SEM-technique for microstructure investigations of post-shocked specimens. Screw rotational structures in the spall zone are thought to be responsible for the more effective shock-wave energy scattering during spallation. Free surface velocity profiles display forward and reverse phase transitions in the all alloys under investigation. The threshold stress for the forward and reverse phase transitions turns out to be practically independent of the chemical and phase compositions of specimens, and monotonously increases with strain rate. Received 7 February 1999 / Accepted 3 November 1999     

Comparative analysis of uniaxial strain shock tests and Taylor tests for maraging steels

High-strength constructional 38XH3MΦA steel and three kinds of maraging steel were tested to determine the yield stress under dynamic loading. The 38XH3MΦA steel was used as central test material to work out the experimental technique and compare the results obtained in different test methods. Results obtained in the plane shock tests under uniaxial strain condition show roughly the same yield stress values as those obtained in Taylor tests.