Metody badań tribologicznych parametrów w inteligentnych bioreaktorach

• Autorzy: Wierzcholski K. , Miszczak A.

Warianty tytułu

EN

Research methods of tribological parameters in intelligent bioreactors

• Języki publikacji: PL

Abstrakty

PL

Tematem przeprowadzonych badań oraz uzyskanych wniosków jest uzasadnienie doboru odpowiednich metod badawczych do wyznaczania parametrów tribologicznych występujących w bioreaktorach w trakcie hodowania chrząstki stawowej lub poszczególnych chondrocytów na potrzeby transplantacji. Badane są zależności wpływu własności mechanicznych warstwy wierzchniej opływanego ciała na lepkość cieczy w cienkiej warstewce przyściennej oraz na powstające w niej siły tarcia. Niniejsza praca charakteryzuje przeprowadzone badania zarówno w aspekcie analitycznym, numerycznym, jak również i doświadczalnym. Autorzy sugerują, że przedstawiony model badawczy ma charakter unikalny, mający nie tylko znaczenie poznawcze, ale i wysoce utylitarne. Badanie zachowania chondrocytów pod wpływem płynów ustrojowych, a zwłaszcza pochodzących z przestrzeni śródstawowej, stanowi całkowite novum mogące odkryć przyczynę nie tylko wielu schorzeń chondropatycznych, ale także spowodować rozwój terapii transplantacyjnej.

EN

The topic of presented research is the substantiation of the proper selection of research methods to the tribological parameters determination occurring in bioreactors during the joint cartilage or articular cells cultivation. The investigations are performed as well in analytical, numerical and in experimental form. After authors suggestion the presented research model has uniqueness character thus has not only cognitive but also the utilitarian meaning. The investigations of behave of chondrocytes (cells) under the organism liquid influence particularly descending from intra-articular space, institute the entirety novelty which can be discover not only the matter of many chondropathy disease but also can be develop the transplantation therapy. The basic method for solving the described scientific problems is the application of the analytical and numerical models to non- Newtonian liquid hydrodynamic flows in thin boundary layers considered on micro- and nano-level. Ranges of the flows are limited by the hyper-elastically and hypo-elastically deformed surfaces. Geometrical features of the surfaces are measured with the use of laser sensors and the atomic force microscope. The analytical models which describe the realistic unsteady hydrodynamic and tribological effects occurring in the non Newtonian liquid flows around cells in the realistic time ranges of nano-seconds and micro-seconds are transformed into the tasks in which the models are represented in time ranges of second. Such models enable to investigate the realistic changes of hydrodynamic effects in very short time periods. Such measurements are very expensive and often not possible to be performed by using present laboratory equipment. The region of flow around the cells and joint cartilages are divided on the three zones. The first zone is of a few dozen nanometers in height and contains the liquid of dynamic viscosity depending on material coefficient of the cells or joint cartilage. In the region of perfused cartilage body or near the cells the flows in micro- canals of the diameter smaller than one micrometer are taken into consideration. The second zone is the thin viscous liquid layer of a few dozen micrometer in height. Here the changes of liquid velocity vector in the direction of layer height prevail over the changes of liquid velocity vector in the plane of the flow. To characterize of mechanical properties of joint cartilage and its cells, classical measurement methods as well as new ones with the use of atomic forces microscopy, are applied. Measurements of geometrical structure of the cell surfaces are performed on nano- level. Values of the hyper-elastic, elastic and visco-elastic material coefficients of the cells and cartilages are measured by taking into account rheological features. Experiments are performed under dynamic loads. Simultaneously, measurements of friction forces and friction coefficients are made by using an oscillation micro-tribo-meter. To measure values of above mentioned material coefficients will be used two kinds of hardness tester, namely a micro-hardness tester with the diameter 350 micrometers and a nano- hardness tester with the diameter of 20 nanometers. The depth of pits during the measurements was about 2 micrometers and 10 nanometers, respectively. This fact enables to estimate the features of boundary layer on the body. The forces and stresses in boundary layer are measured by using laser- beam method. Regardless of the above described measurement methods applied to cell bodies, the measurements of thin layer features of osmotic and pharmacological liquids flowing around the cells, are also assumed. Such liquids have non-Newtonian and anisotropic features with different properties in different directions. During the measurements the atomic force microscope will be used. Measurements in three static-dynamic states are provided for. The first of them is based on the fact that hardness tester is in static- dynamic motion. The second state is characterized by the two- directional motion of the groundwork on which the liquid rests. The third state is assumed for the provoked motion of the liquid inside the thin boundary layer resting on the static, motionless groundwork. The measurements are performed in such thermal conditions as to bring them nearer the human body temperature. The performed cells during the cultivation in bioreactors. Additionally, gain of many tribological and biophysical parameters indispensable for cells cultivation, is expected. For fully successful realization of the presented tasks it is necessary to build the mini-bioreactor coupled with the atomic force microscope. By using this microscope it is possible to control many data on biological liquid flow and temperature during the performed measurements and cell cultivation. To solve analytically sets of non linear differential equations is not possible in each case. In such situations the numerical methods must be applied. To achieve the numerical solutions of the presented problems the method of finite differences is applied. In this method the partial derivatives are replaced with the finite differences. The application of difference schemas in the difference method permits to convert the differential equations into the difference equations where the numerical solutions are executed on the ground of the calculated nets. Topology of the nets is optimized by using the least distances between the nods of the nets in the a properly selected metric space to assure stability and convergence of the numerical solutions. The numerical calculations are performed by using Matlab 7.3 Program. The values determined in the numerical way will be verified experimentally in mini-bioreactors. Experimental verification of the analytical and numerical models for nutrient liquid flows during the cells cultivation will be also performed in mini-bioreactors. Also, distributions of liquid velocity and friction forces in thin layers will be verified.

Słowa kluczowe

PL

bioreaktory; siły tarcia; metody wyznaczania sił tarcia

EN

bioreactors; friction forces; determination of friction forces

• Wydawca: Stowarzyszenie Inżynierów i Techników Mechaników Polskich
• Czasopismo: Tribologia
• Rocznik: 2007
• Tom: nr 3-4
• Strony: 355--368
• Opis fizyczny: Bibliogr. 17 poz., rys.

Twórcy

autor

Wierzcholski K.

autor

Miszczak A.

• Gdynia Maritime University, Morska St., 81-87, 81-225 Gdynia

Bibliografia

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