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The fixture of optical elements in optomechanical assemblies is a field that develops depending on ever-increasing demands on optical systems, namely on their performance, the accuracy of the fit for the lenses, on the installation space, the resistance of the assemblies, etc. Equally important is the view in terms of the production demand for such a system, which is also growing. The article presented here deals with a theoretical understanding of the issues concerning the free bonding of lenses, i.e. fitting the...

The matrix of silicon carbide (SiC) is sufficiently rigid and strong, but in order to fully realize its potential capabilities, it is necessary to reduce its fragility and increase its reliability when used under shock loading conditions, which is achieved by creating ceramic composites based on it. Zirconia (ZrO2) was chosen as a hardening additive, since it has very high resistance to crack propagation and thermal, electrical, optical, strength, and other properties. Stabilization of the cubic phase of zirconia ...

Paper presents usage of viscoelastic material in the body of turning tool holder in order to damp the vibrations in the turning process. The standard approach to designing is the strength and stiffness based designing resulting from static material properties. However, each dynamically loaded structure is the subject of vibrations. Thus the dynamic material properties (damping measures) are of equal importance as vibrations are a part of the machines and devices performance. Their occurrence cannot be prevented be...

Currently, the urgent task associated with the development and production of new, cheaper, building materials. Rocks have a reserve of free internal energy, which is determined by the method of their formation. The use of this energy reserve can reduce the work that needs to be done during the technological transformation of raw materials in the production of building materials. In this paper, it is proposed to evaluate the efficiency of using various finely dispersed systems to use as a criterion - surface activi...

One of the most important parameters of pavement serviceability in terms of view road safety is without doubt skid resistance. By now, a number of different methods and devices have been developed for both friction and texture evaluation. However, while measurements of friction coefficients tend to be subject to a large number of boundary conditions, texture measurements are affected by device limits without the possibility of detecting surface irregularities at the microtexture level, which appears to be crucial ...

Based on the nanomaterials market research, the global production of cobalt (II, III) oxide (Co3O4), aluminum oxide (Al2O3) and magnesium oxide (MgO) nanoparticles is large-scale (> 100 tons/year), which leads to their contamination of environmental objects and accumulation in organisms. Research and scientific forecasting of the potential hazard and the features of the accumulation of Co3O4, Al2O3, and MgO nanoparticles have been carried out. According to the research results of the physical properties of the tes...

This article presents the results of the studies that were conducted by the authors for determining the influence of the cycles of heat treatments on the structure and mechanical properties of dual-phase steel with a low manganese content. For the research in discussion, was used an alloy with 0.094% C and 0.53% Mn which was subjected to several cycles of heat treatments (consisting of full annealing, normalizing, subcritical annealing, full quenching, intercritical quenching). The metallographic analyzes were per...

The article presents results of the studies conducted by the authors for determining the influence of the structure succession on the volume fraction of martensite and ferrite microhardness in a dual-phase steel with low manganese content. For the research in discussion, an alloy with 0.094% C and 0.53% Mn (Si, Cr, Ni, Mo, Al, Cu, P, and S below 0.1%) was used. This alloy was subjected to several cycles of heat treatments (consisting of full annealing, normalizing, subcritical annealing, full quenching, intercriti...

Purified natural clinoptilolite as well as clinoptilolite converted into hydrogen and sodium form have been contacted with 0.1 mol/L silver nitrate solution at a ratio solid to liquid equal to 1 to 20, in order to load silver ions (Ag+) on the zeolite support. It has been found that sodium modified clinoptilolite exchanged in highest degree Ag+ ions, followed by natural zeolite. Preliminary transformation of natural clinoptilolite into hydrogen form leads to decreasing of zeolite ability to bind Ag+ ions. The kine...

Silicon carbide is a promising material for heat-loaded units due to its high strength at elevated (up to 1500 °C) temperatures and excellent thermal conductivity. Silicon carbide ceramics is widely used for structural applications, yet production of such materials belongs to extremely energy-consuming industries, thus it becomes an important task to carefully adjust ceramics compositions and methods of manufacturing. The present paper discusses the correlation between mechanical behaviour (dependent variable, cal...

One of the possible ways of transition to the eco-friendly energy is widening the use of the solar cells. It requires the enhancement of their efficiency and the reduction of the cost of manufacture. One of the most common tools for producing silicon films for the solar cells is the Plasma Enhanced Chemical Vapor Deposition (PECVD). The present paper describes a new Particle-In-Cell code for simulation of the PECVD reactor. The goal of the research is the optimization of real PECVD reactor by means of the simulati...

Various eco-friendly and cost-effective hydrocarbons clean-up methods based on natural sorbents were developed and tested, in order to prevent the massive environmental damage due to the petroleum spills. Among these sorbents, natural zeolitic tuffs are easily available and have numerous adsorptive properties that make them appropriate for the removal of petroleum substances. This study aims to preliminary investigate the sorption capacity of natural zeolites from a deposit located at Racos, Brasov County, Romania...

The research and evaluation of calcium oxide nanoparticles? (CaO) accumulation and toxicity when ingested orally were carried out. The results, obtained after the study of CaO nanopowder by scanning electron microscopy method, demonstrate, that a large proportion of particles in its composition have a size of up to 100 nm, a rounded shape and a smooth surface, while the microparticles of the chemical analog have a cubic shape with a rough surface. According to the death rate, LD50 values were calculated for male W...

The aim of this work is to experimentally study the synthesis of carbon nanotubes and nanofibers by catalytic pyrolysis of methane-hydrogen mixtures, as well as to develope a kinetic scheme that takes into account the accelerating and suppressing effect of hydrogen on pyrolysis. Carbon nanotubes were synthesized in a laboratory kinetic setup with a vertical quartz reactor at a temperature of 700?. The oxide system (Fe0.45Co0.15Al0.40)2O3 obtained by combustion method was taken as a catalyst. The hydrogen concentra...

The research of 2D carbon-based nanomaterials has become very intensive since the discovery of graphene. Many different preparation procedures of graphene and graphene derivatives have been reported. The aim of this paper was to prepare and characterize partially oxidized graphite oxides, which were prepared from nanographite by adding different amounts of potassium permanganate as an oxidizing agent. The C/O ratio was evaluated from X-ray photoelectron spectroscopy, energy dispersive spectroscopy, and elemental a...

Being released into the environment, the nanosized particles are present in it in the form of a colloid. At the same time, the colloid has an ability to change its properties, including its dimensionality, depending on the physical conditions, as well as composition of the dispersing medium. Nevertheless, this circumstance is irrelevant when assessing the risk associated with the spread of nanosized particles in the environment. The conditions under which the colloid retains its property of nanoscale dimensionalit...