ABSTRACT
The paper presents the results of studying the effect of modifying low-chromium hypoeutectic cast iron (chromium content about 1%) with boron- and barium-containing additives on its structure and hardness. The modification was carried out with carbothermicferroboron (0.08% of weight of the liquid metal); ferrosilicobarium (0.05% of weight of liquid metal); complex boron barium ferroalloy (0.14% by weight of liquid metal). The microstructure and properties were compared with a sample of unmodified cast iron of the same composition. The Thixomet Pro software was used as the main method of the quantitative analysis of the microstructure that allows quantitative metallographic analyzing with high accuracy and repeatability. The analysis of the results obtained shows a positive effect of modification on changes in the microstructure. In all the experimental samples, grinding and more uniform distribution of carbides, as well as transformation of the carbides morphology from dendritic to compact granular form, take place. Pearlite colonies in the modified cast iron are characterized by a higher degree of dispersion than in the reference sample. Such changes in the structure lead to increasing the hardness of the prototypes.
ABSTRACT
There have been examined 90 practically healthy male-shift-workers 21-58 aged and 21-60 aged (average age 41.4 +/- 1.4 and 48.6 +/- 1.3) who worked for a long period of time in the North on shift at the enterprises of JS "Yamburggasdobycha" at the moment of examination. It was revealed a high content of glycosaminoglycans (GAG) in blood serum (2.20 +/- 0.12 mmol/l), accumulation of LPO products (3.45 +/- 0.18 nmol MDA/ml) against the background of decreased glutationreductase activity (0.38 +/- 0.04 mkmol/l hour). Level of total cholesterol was increased at standard content of HDL (6.1+0.2). It can be concluded that definition of GAG and MDA in blood is one of the significant criteria, reflecting adaptative tension and premature aging of shift-workers.
