[Acoustic microscopy application for the evaluation of restorative materials bonding quality. Experimental investigation].

Ultrasound transmission and reflection at the interface between restorative material and tooth tissue have been investigated using experimental flat-parallel models and whole extracted human teeth with restorations. It has been found that in the case of good bonding the ultrasound wave energy practically does not reflect at the cement/dentin interface and propagates into dentin layer. If any microscopic cavity had been formed between cement and dentin, the most part of the acoustic energy would be reflected from the interface between cement and gaseous or liquid contents of that cavity. The results acquired have been used for the interpretation of morphological peculiarities of the adhesive bonding area in visual images, non-destructively obtained in acoustic microscope ultrasound frequency - 50 MHz. The differences discovered could be used as a base for the design and development of new ultrasound methods for the restorative materials bonding evaluation as well as for secondary caries revealing.

[Application of the method of acoustic microscopy for the study of eye tissues].

The paper describes the results of evaluation of potentialities of the application of scanning acoustic microscopy, which is still relatively new and as yet uncommon method of biological research, for the supravital study of animal eye structure in species with different eyeball size. Using the eyes of a goat, quail embryo (in situ) and frog tadpole (in vivo) as the examples, it was shown that non-destructive nature of the method used allows for the study of peculiarities of major morphologic structures in the state that is close to the natural one. Some acoustic images are presented showing eye structural elements along with the results of quantitative characteristic of the cornea, sclera and iris.

The use of acoustic microscopy to study the mechanical properties of glass-ionomer cement.

OBJECTIVES: The aim of the study was to investigate the relationship between microstructure, acoustic and mechanical properties of hardened dental cement samples, prepared with different powder/water ratios. METHODS: Glass-ionomer dental cement samples, prepared with a standard amount of cement powder and different amounts of water have been examined after being hardened. Surface microstructure and ultrasound, longitudinal and shear velocities were obtained with a scanning acoustic microscope. Conditional effective elastic modulus and Poisson's ratio have been calculated using longitudinal and shear sound velocity values. Then on the same samples elastic modulus and microhardness have been determined by standard tests. Additional samples have been used to determine compressive strength. RESULTS: Density; conditionally instantaneous elastic modulus; high-elasticity modulus and compression strength of the samples decrease when large amounts of water were used for their preparation. At the same time porosity and microhardness of the cement matrix increase. Acoustic parameters and parameters of elasticity, calculated on the basis of sound velocity, demonstrated changes, similar to those obtained in standard mechanical tests. SIGNIFICANCE: The established relation between microstructure, acoustic and mechanical parameters demonstrated a high capacity of acoustic microscopy application for non-destructive characterization of dental materials. A particular advantage of the acoustic microscopy is the opportunity to evaluate microstructure and mechanical properties on the same sample.

[The effect of exposure to radiation and other industrial factors on the morbidity of the personnel in enterprises in the mining and processing of rare-earth metal ores]. / Vozdeistvie radiatsionnykh i drugikh proizvodstvennykh faktorov na zabolevaemost' personala predpriiatii po dobyche i pererabotke rud redkozemel'nykh metallov.

Multivariate regression analysis proved that radiation of allowable level had no unfavorable influence on morbidity with transitory disablement. Increased from 0.15 to 2.0 microGy/hr dose rate of gamma radiation at the workplaces resulted in slightly lower morbidity. Unfavorable influence on morbidity was caused by physical factors (noise, vibration, microclimate, work hardness), irritating and neurotoxic chemicals in amounts which seldom exceeded the allowable norms, hostile climate and geographic conditions.

[Indicators of mental status, catecholamine excretion, lipid metabolism and hemostasis in air-traffic controllers at automated and non-automated stations during their non-work days]. / Pokazateli psikhicheskogo sostoianiia, ekskretsii katekholaminov lipidnogo obmena i gemostaza u aviadispetcherov avtomatizirovannykh i neavtomatizirovannykh punktov v den' otdykha.

The changes reported during rest days among air-traffic controllers working at automated and non-automated stations demonstrated the similar degree of functional rehabilitation of the body systems, thus a positive impact of automatization on those working at specific air-traffic management stations being emphasized.

[Biochemical and psychological indicators in air controllers in the "pre-start" state before beginning work activities]. / Issledovanie biokhimicheskikn i psikhologicheskikh pokazatelei u aviadispetcherov v "predstartovom" sostoianii pered nachalom professional'noi deiatel'nosti.

The biochemical parameters (renal excretion of catecholamines, lipid metabolism, cholinesterase activity in blood, excretion of sodium and potassium in the saliva) and psychological parameters (attention concentration, anxiety, rate of information processing) of air controllers were determined immediately before their work shift. Most of the parameters were significantly changed.