Simple mathematical models of high energy ion beam assisted deposition concentration profiles in binary thin films.

Mathematical models of composed high energy ion beam assisted deposition (IBAD) concentration profiles of implanted component in binary thin films are described. Yields of the backscattered ions and sputtering of the deposited component are considered. A Gaussian probability density is assumed to apply to the ion range distribution. The construction of concentration profiles of various shapes is considered. These profiles should of course be constructed based on continuous changes of the process parameters, but certain technical problems can arise with this continuous parameter changes. Therefore, it has been assumed that the changes to the process parameters are discrete and proceed in several steps. The resulting mathematical models are combinations of error functions. Mathematical models can be used as regression functions for the determination of some parameters, e.g., the sputtering yield. Based on the mathematical model the gradient concentration profile of nitrogen in the SiNx film was experimentally produced by the IBAD method, measured by Rutherford backscattering spectroscopy and compared with the mathematical model.

Analyses of the temporomandibular disc.

This project is the beginning of a large research work with a goal to develop a new total replacement of temporomandibular (TM) joint. First aim of this work was to determine the relative displacement of the TM disc and the mandible during mouth opening. The movement of the TM disc was studied using a magnetic resonance imaging. Sagittal static images in revolved sections of the TM joint were obtained in various positions of jaw opening from 0 to 50 mm. The results provided a description of the TM disc displacements as a function of jaw opening. The displacements of the mandible and TM disc were about 16 mm and 10 mm respectively at mouth opening of 50 mm, maximum rotation of the mandible was 34s. The results of these measurements can be used for clinical diagnostics and also they were used as inputs for the follows finite element analysis (FEA). Second aim of this work was to create stress and strain analysis of TM joint using non-linear FEA. Complex of TM joint consists of mandibular disc, half skull and half mandible during normal jaw opening. The results illustrate the stress distributions in the TMJ during a normal jaw opening.

Sliding properties of plasma assisted CVD CNchi coatings for metal bioimplants.

Coatings of CNchi, have been prepared on the substrates of material Ti6Al4V, of which the human joint replacements are made. The deposition of the CNchi coating was carried out by PACVD method in apparatus with standard arrangement. The methane and nitrogen have been used as precursors for CNchi compound. The infrared absorption spectroscopy and Rutherford backscattering spectroscopy were applied on diagnostics of prepared CNchi layer. Beside carbon and nitrogen the hydrogen and oxygen were found in the coatings. The sliding tests were carried out with the samples. The counter parts were the cylinders made of the polyethylene of the same type as for big joint prostheses is used. The tests were carried out in the medium of physiological solution. The CNchi coatings perform well under the lower load of 25 and 50 N. When the load is increased to 100 N, the friction coefficient slowly increases, but measured values of mu are typical for boundary lubrication.

[Development of the ceramic sandwich cup used for the hip joint prosthesis.]. / Vývoj keramické sendvicové jamky pro náhradu kycelního kloubu.

The abrasion of the polyethylene seems to be the most important factor participating on the endoprosthesis loosening. From this reason, the ceramics (AI2O3) was introduced for the both parts of the prosthesis, i. e. the head and the cup. It appears that the friction resistance is an important factor for the comparison of the hitherto applied endoprosthesis designs with the new developed type. The frictional resistance in the hip joint total prosthesis was measured by means of a testing device which allowed a swinging motion of the ceramic ball in the tested cup in the range of +/-25 degrees . This measurement was carried out at the loading levels being 0; 500; 1000; 1500 and 2000 N. For the comparison of the frictional resistance of single measured couples "cup-head", the energy consumed was ascertained which was necessary for including a swinging motion over the time interval of 35 sec. Ceramic cups manufactured by a. s. DIAS Turnov were used for the measurement. Altogether eight couples "ceramics-ceramics" having the diameter differences ranging from 0,022 mm to 0,137 mm and one friction couple "polyethylene cup-ceramics ball" were measured. The research of influence of different lubricants was also done. Key words: sandwich cup, total prosthesis, ceramics--ceramics, bioceramics, frictional resistance.