Wood as a model material for medical biomaterials. In vivo and in vitro studies with bone and Betula pubescens Ehrh

Novel biomaterials are needed to fill the demand of tailored bone substitutes required by an ever‐expanding array of surgical procedures and techniques. Wood, a natural fiber composite, modified with heat treatment to alter its composition, may provide a novel approach to the further development of hierarchically structured biomaterials. The suitability of wood as a model biomaterial as well as the effects of heat treatment on the osteoconductivity of wood was studied by placing untreated and heat‐treated (at 220 C , 200 degrees and 140 degrees for 2 h) birch implants (size 4 x 7mm) into drill cavities in the distal femur of rabbits. The follow‐up period was 4, 8 and 20 weeks in all in vivo experiments. The flexural properties of wood as well as dimensional changes and hydroxyl apatite formation on the surface of wood (untreated, 140 degrees C and 200 degrees C heat‐treated wood) were tested using 3‐point bending and compression tests and immersion in simulated body fluid. The effect of premeasurement grinding and the effect of heat treatment on the surface roughness and contour of wood were tested with contact stylus and non‐contact profilometry. The effects of heat treatment of wood on its interactions with biological fluids was assessed using two different test media and real human blood in liquid penetration tests. The results of the in vivo experiments showed implanted wood to be well tolerated, with no implants rejected due to foreign body reactions. Heat treatment had significant effects on the biocompatibility of wood, allowing host bone to grow into tight contact with the implant, with occasional bone ingrowth into the channels of the wood implant. The results of the liquid immersion experiments showed hydroxyl apatite formation only in the most extensively heat‐treated wood specimens, which supported the results of the in vivo experiments. Parallel conclusions could be drawn based on the results of the liquid penetration test where human blood had the most favorable interaction with the most extensively heat‐treated wood of the compared materials (untreated, 140 degrees C and 200 degrees C heat‐treated wood). The increasing biocompatibility was inferred to result mainly from changes in the chemical composition of wood induced by the heat treatment, namely the altered arrangement and concentrations of functional chemical groups. However, the influence of microscopic changes in the cell walls, surface roughness and contour cannot be totally excluded. The heat treatment was hypothesized to produce a functional change in the liquid distribution within wood, which could have biological relevance. It was concluded that the highly evolved hierarchical anatomy of wood could yield information for the future development of bulk bone substitutes according to the ideology of bioinspiration. Furthermore, the results of the biomechanical tests established that heat treatment alters various biologically relevant mechanical properties of wood, thus expanding the possibilities of wood as a model material, which could include e.g. scaffold applications, bulk bone applications and serving as a tool for both mechanical testing and for further development of synthetic fiber reinforced composites.

Päätöksenteko innovaatioiden alkuvaiheessa teollisuusyrityksessä

Decision-making and the available information are important components of successful innovations. However, innovation-related decision-making in large and multinational industrial companies can be considered complex and challenging. The purpose of this study is to clarify what the innovation channels are, what kind of information is needed to make decisions and how the decision-making mechanism can be improved in Target Company. In addition, the current state of innovation management and decision-making are clarified and the suggestions for improving the current decision-making mechanism are presented in this study. The empirical study proves that the innovation-related decision-making has not been systematic and efficient, although the innovation culture and activity together with the management tool are on a good level. In order to improve the decision-making in Target Company, the importance of the most relevant decision-making criterions (business need, strategic fit, feasibility) need to be underlined during the idea gathering phase. In addition, business unit –specific decision-making in the front-end of innovations needs to be enhanced and developed.

Myös aikuiset tarvitsevat tukea oppimisvaikeuksiin

Kuntoutussäätiö toteutti vuosina 2006-2010 Opi oppimaan -projektin, jossa kehitettiin uusia palveluja oppimisvaikeuksista kärsiville aikuisille ja nuorille.

Yrittäjäminän kritiikki

Kirjallisuusarvostelu

Kaupanalan muutos ikääntyvien silmin

Tarita Ruoholinnan väitöskirja Ikääntyvät työelämässä : päihittääkö nuoruus ja koulutus aikuisuuden ja kokemuksen? (Turun yliopisto 2009).

Naiset ja kansansivistyksen suuri kertomus

Tarja Langin väitöskirja Myyttisestä sankarirehtorista opistoäidiksi ja manageriksi : sukupuolen näkökulma kansalais- ja työväenopiston johtajuuteen (Helsingin yliopisto 2010).

Asiantuntijuutta tukevaa johtamista

Kirjallisuusarvostelu

Miten vastustaa seksuaalista häirintää härskiintyvässä yhteiskunnassa

Kirjallisuusarvostelu