The strength of materials is a complex function which involve two main components, material nature and the presence of defects. Usually glasses exhibit a fragile behavior due to a numerous flaws and the effect is a large range of data scattering in tensile strength measurement. The Weibull probability density function was applied to describe the scatter of experimental data in tensile test, which emphasize a difference between variance in case of tensile strength of three stainless steel grades and glass epoxy composite. The main goal is mathematical modeling of those distributions and finding of equations which predict the probability of failure for a sample subjected to a specific stress.

The aim of the paper was to develop a device (“pin-on-disc” type) for the measurement of friction in plane friction couplings with sliding movement. On tribometric device (made in our laboratory) we can measure the friction force, friction coefficient and wear, for different loading conditions, speeds, time and material coupling. For the measurement of the frictional force as well as of the coefficients of friction, mainly the method with a resistive tensiometric transducer is used. With a DataQ DI 245 data acquisition board it is possible to record up to 2 kHz frequencies in the range of -10 ÷ +10 mV with a resolution of 13 bits. To test the functionality of the device, a preliminary test was carried out for a steel pin- on- cast iron disc, for different values of the normal pushing force. The device was calibrated and the measurement results were recorded and processed on the computer.

The paper presents an overview of (i) the different polluting materials, classified according to their (bio)degradability, (ii) the sources of pollution (iii) the general effects of pollution on natural resources and on the economy and people’s health. The paper also summarizes directions/solutions to eliminate these effects, including “eco” technologies, and their effectiveness on environmental conservation and regional and global ecosystem protection, in the context of a clean and sustainable environment, in accordance with the 2030 Agenda for Sustainable Development.

The glass obtained by the sol-gel method was immersed in a simulated body fluid solution, in order to observe the structural and morphological changes on its surface. Infrared spectroscopy - FTIR and electron microscopy SEM analyses showed the formation of apatite on the surface of the synthesized glass.