Search Results (78)
Plasma treatment of polymers for biomedical applications
Vascular grafts made of polyethyleneterephthalate (PET) polymers have successfully replaced large-diameter blood vessels, but the long-term performance of small-diameter (< 6 mm) vascular grafts is still disappointing. The main problem is insufficient biocompatibility of polymer surface with blood, which causes complications after implementation; such as thrombosis or restenosis. These complications …
Measuring the probability for heterogenous recombination of hydrogen and oxygen atoms on surfaces of fusion relevant materials
This thesis presents studies of probability of heterogeneous recombination of oxygen and hydrogen atoms on surfaces of different types of carbon-based materials. The probability of heterogenous recombination is described with a quantity called recombination coefficient, which is defined as the probability that an atom which impinges upon a solid surface …
Nonequilibrium Dynamics of Charge and Collective Modes in Charge Density Waves Compounds
This thesis presents studies of ultrafast carrier relaxation dynamics in charge density wave (CDW) materials by means of femtosecond time-resolved optical spectroscopy. In these experiments, a femtosecond pump pulse excites electrons via interband transitions, thereby changing the optical properties of the material. The dynamics of relaxation processes is then recorded …
Hydrogen absorption in Ti-Zr-Ni alloys
Our research focused on the formation of Ti40Zr40-xNi20Cux (x=3, 5), Ti45Zr38-xNi17Cux (x=3, 5), Ti53Zr27-xNi20Cux (x=3, 5) and Ti58Zr24-xNi18Cux (x=3, 5) icosahedral (i-phase) quasicrystals by three different techniques and their subsequent characterization and high-pressure hydrogenation. The quasicrystals of this system are thermodynamically stable and they have a relatively good affinity for …
Na0.5Bi0.5TiO3-based materials with mechanical-stress-dependent dielectric properties
The stress dependence of the electrical permittivity offers a convenient way of measuring pressure. This effect is suitable for static and quasi-static stress applications, where the conventional method based on the piezoelectric effect becomes inadequate. Although the principle of applying this effect for pressure sensing has been known for almost …
Plasma sterilization of microorganisms
The sterilization efficiency of oxygen plasma was studied. Plasma was created in pure oxygen with an inductively coupled radiofrequency discharge. The discharge power was estimated to about 180 W. Plasma parameters were measured with a double Langmuir probe and a catalytic probe. Plasma parameters depended on pressure in the discharge …
Monitoring of the product quality in manufacturing industries
Unexpected production breakdowns and unpredictable defects in product quality remain critical problems in modern manufacturing systems. Usually occuring by no obvious exterior cause and often during periods of smooth production, they lead to production losses and reduced process availability, which results in lower profit rates. Conventional statistical methods of process …
Network Models of Self-Assembled Functional Materials
The fabrication of functional materials composed of metallic nanoparticles is one of the most important steps in the contemporary nanotechnology. Nonlinear selfassembly of nanoparticles into macroscopic aggregates are promising methods in which various structures can be obtained by tuning certain control parameters. Such large-scale aggregates exhibit new physical features, which …