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1

Badania oporności elektrycznej zaprawy cementowej zbrojonej włóknami węglowymi spowodowanej długością spękań i odkształceń w trakcie pomiarów naprężeń rozciągających przy zginaniu trójpunktowym i przy rozłupywaniu

Teomete E.

Cement Wapno Beton

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2017

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R. 22/84, nr 1

1--17

PL

Rozwój samo-śledzących inteligentnych materiałów dla przemysłu budowlanego jest ważnym zadaniem, mającym na celu ich zabezpieczenie przed zniszczeniem i zapewnienie długiego okresu eksploatacji. W artykule zbadano korelację pomiędzy długością rysy a opornością elektryczną matrycy cementowej zbrojonej włóknami węglowymi stosując trzy-punktowe zginanie próbek i mierząc równocześnie wzrost długości rysy oraz oporność. Znaleziono po raz pierwszy bardzo dobrą korelację pomiędzy tymi zmiennymi dla zbrojonych włóknami węglowymi kompozytów cementowych. Bardzo dobra korelacja liniowa pomiędzy naprężeniem rozciągającym, badanym przy rozłupywaniu próbek, i opornością elektryczną takich samych kompozytów cementowych została także ustalona. Zmierzony bardzo duży wskaźnik określający zmianę oporności elektrycznej w stosunku do długości rysy wynoszący 1435 jest największym wskaźnikiem matrycy w kompozytach cementowych. Kompozyty cementowe opracowane w trakcie tych badań mogą być stosowane do wykrywania rys i odkształceń i ich śledzenia w konstrukcjach betonowych.

EN

Development of self-sensing smart materials for construction industry is an important task to protect the lives and to achieve optimal asset management strategies. In this study, five different carbon fibre reinforced cement matrix composites were designed with carbon fibres having length of 3 mm. In order to investigate the relation between the crack length and electrical resistance change notched three-point bending test was applied to the rectangular prism samples. During the bending test, crack length and electrical resistance were simultaneously recorded. A strong linear relationship was found between the crack length and electrical resistance change. Correlations between the crack length and electrical resistance change were determined for the first time in the literature for carbon fiber reinforced cement composites. Tensile strain and electrical resistance were simultaneously measured during the split tensile tests and a strong linear correlation between the tensile strain and electrical resistance change was determined. The maximum gage factor was obtained at the percolation threshold value due to the shift in the conduction system from post-percolation to pre-percolation by strain. Gage factors as high as 1435 were measured which is the highest gage factor reported for cement matrix composites. The cement composites designed in this study can be used for crack detection and strain sensing in health monitoring of concrete structures.

2

Human bone-derived cells on C-C composites treated by grinding, a-C:H coating, laser irradiation and laser perforation

Bacakova L., Beranek L., Bacakova M., Soukup D., Lisa V., Dvorak R.

Engineering of Biomaterials

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2008

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Vol. 11, no. 75

2--6

EN

Carbon fiber-reinforced carbon (CFRC) composites were modified by grinding with abrasive papers, laser irradiation, coating with diamond-like carbon (DLC), creation of pores by laser perforation and various combinations of these treatments, and seeded with human osteoblast-like MG 63 cells. Twenty four hours after seeding, the lowest cell numbers were obtained on the non-ground, non-coated composites with Type 1 laser perforations (diameter 0.1 mm, depth 0.2 mm, spacing 0.3 mm), i.e., on samples with relatively high surface roughness (R a = 17.7 ± 0.9 μm, S = 93.0 ± 2.0 μm). On the other hand, the cells on these samples were well-spread, adhering with a relatively large cell-material projected area. In comparison with these samples, a significantly higher number of cells were obtained on composites treated with a DLC coating, especially those with laser perforation 2 (diameter 0.4 mm, depth 0.8 mm, spacing 1.2 mm). The cells on both types of laser-perforated samples started to colonize pores created by the laser beam.

3

Human osteoblast-like MG 63 cells in cultures on carbon fibre-reinforced carbon composites coated with zirconium nitride

Paul J., Bacakova L., Douderova M., Stary V., Vyskocil J., Lisa V., Ślósarczyk A., Zima A.

Engineering of Biomaterials

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2007

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Vol. 10, no. 67-68

5-8

EN

Zirconium nitride is considered as a promising material for strengthening for surface of various materials, especially those designed for hard tissue surgery. In this study, five groups of materials were prepared: non-modified carbon fibre-reinforced carbon composites (CFRC), CFRC ground with metallographic paper, non-ground CFRC with a layer of ZrN deposited by magnetron sputtering, ground CFRC with a ZrN layer deposited by the arc technique, and ground CFRC with a ZrN layer deposited by a magnetron. We found that all samples gave good support for the adhesion and growth of human-osteoblast-like MG 63 cells, though the cell numbers on these materials were often lower than on standard cell culture polystyrene dishes and microscopic glass coverslips. Nevertheless, ZrN films can be considered as suitable materials for surface modification of bone implants in order to improve their mechanical properties and their integration with the surrounding tissue.

4

Influence of surface properties of carbon based materials on cell spreading

Douderova M., Bacakova L., Stary V.

Inżynieria Biomateriałów

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2004

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R. 7, nr 37

17-17

EN

Carbon materials are generally well tolerated by animal cells. The possibility of applying carbon fiber reinforced carbon (CFRC) composite materials is given by their excellent biocompatibility and porosity, coupled with a modulus which can be tailored to be similar to that of bone. This makes them an attractive material for bone plates and implants in orthopaedic and dental surgery. It is known that the volume properties of a material usually have little or no influence on the surrounding living tissue cells. In general, biocompatibility is controlled mainly by the interface between biomaterial and living tissue cells. The literature and our study indicate that the interaction at the interface is specifically controlled by the surface morphology (i.e. especially by surface roughness), and by the chemical state of the surface - by hydrophobia (wettability), free chemical bonds and present chemical groups, etc. Never-theless, biocompatibility can be improved by a suitable change of these parameters. There are several possible methods for influencing the roughness and chemical state of the surface. One way to change the surface properties is by preparing a suitable coating. The properties of the surface are controlled by process technology, and the grinding and polishing of the substrate can be used for roughness control. Till now we studied the influence of the surface on the cell adhesion and on the rate of the cell growth. There, we have studied the influence of a surface coating of CFRC using a several types of layers on the base of carbon. In our present contribution we continue in this work using the surfaces of CFRC in native and polished states, both covered by layers of amorphous carbon, or titanium with carbon or pyrolitic graphite. The vascular smooth muscle cells were grown on these surfaces. The purpose of this paper is to find the influence of the surface on the important parameter of tissue cell growth - the spreading of cells. The main topic of this work is therefore the measurement and statistical evaluation of the cell area on the various types of surfaces. It will be shown, that the cell spreading is strongly influenced by various surface roughness and also its chemical state.

5

Adhesion, differentiation and immune activation of human osteogenic cells in cultures in carbon-fibre reinforced carbon composites

Bacakova L., Stary V., Glogar P., Lisa V.

Inżynieria Biomateriałów

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2003

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R. 6, nr 30-33

8-9