Gas-foamed poly(lactide-co-glycolide) and poly(lactide-co-glycolide) with bioactive glass fibres demonstrate insufficient bone repair in lapine osteochondral defects

Deep osteochondral defects may leave voids in the subchondral bone, increasing the risk of joint structure collapse. To ensure a stable foundation for the cartilage repair, bone grafts can be used for filling these defects. Poly(lactide-co-glycolide) (PLGA) is a biodegradable material that improves bone healing and supports bone matrix deposition. We compared the reparative capacity of two investigative macroporous PLGA-based biomaterials with two commercially available bone graft substitutes in the bony part of an intra-articular bone defect created in the lapine femur. New Zealand white rabbits (n = 40) were randomized into five groups. The defects, 4 mm in diameter and 8 mm deep, were filled with neat PLGA; a composite material combining PLGA and bioactive glass fibres (PLGA-BGf); commercial beta-tricalcium phosphate (beta-TCP) granules; or commercial bioactive glass (BG) granules. The fifth group was left untreated for spontaneous repair. After three months, the repair tissue was evaluated with X-ray microtomography and histology. Relative values comparing the operated knee with its contralateral control were calculated. The relative bone volume fraction ( increment BV/TV) was largest in the beta-TCP group (pPeer reviewe

Future Combustion Technology for Synthetic and Renewable Fuels in Compression Ignition Engines (REFUEL) - Final report

This domestic project, Future Combustion Technology for Synthetic and Renewable Fuels in Compression Ignition Engines (ReFuel), was part of a Collaborative Task "Future Combustion Technology for Synthetic and Renewable Fuels in Transport" of International Energy Agency (IEA) Combustion Agreement. This international Collaborative Task is coordinated by Finland. The three-year (2009-2011) project was a joint research project with Aalto University (Aalto), Tampere University of Technology (TUT), Technical Research Centre of Finland (VTT) and Åbo Akademi University (ÅAU). The project was funded by TEKES, Wärtsilä Oyj, Neste Oil Oyj, Agco Sisu Power, Aker Arctic Technology Oy and the research partners listed above. Modern renewable diesel fuels have excellent physical and chemical properties, in comparison to traditional crude oil based fuels. Purely paraffinic fuels do not contain aromatic compounds and they are totally sulphur free. Hydrotreated Vegetable Oil (HVO) was studied as an example of paraffinic high cetane number (CN) diesel fuels. HVO has no storage and low temperature problems like the fatty acid methyl esters (FAMEs) have. The combustion properties are better than those of crude oil based fuels and FAME, because they have very high cetane numbers and contain no polyaromatic hydrocarbons (PAH). With low HVO density, viscosity and distillation temperatures, these advantageous properties allow far more advanced combustion strategies, such as very high exhaust gas recirculation (EGR) rates or extreme Miller timings, than has been possible with current fossil fuels. The implementation of these advanced combustion technologies, together with the novel renewable diesel fuel, brought significant nitrogen oxides (NOx), particulate matter (PM) emission reductions with no efficiency losses. The objective of ReFuel project was to develop new extremely low emission combustion technologies for new renewable fuels in compression ignition engines. The target was to decrease emissions at least by 70%. The scope was to utilize the physical and chemical properties of the renewable fuels that differ from properties of the traditional crude oil based fuels and to develop optimum combustion technologies for them. The project focused firstly, on paraffinic high cetane number fuels i.e. hydrotreated vegetable oil fuel as a typical representative of this kind of fuel and secondly, on fuels with high content of oxygenates. This was implemented by blending oxygenate to HVO fuel.

Yksisylinterisen tutkimusmoottorin kampi- ja venttiilikoneiston sekä ahtojärjestelmän simulointi

Teknillisen korkeakoulun polttomoottorilaboratorioon rakennetaan 1-sylinterinen optinen tutkimusmoottori. Moottori rakennetaan 6-sylinterisen nopeakäyntisen dieselmoottorin pohjalta. Tämän diplomityön tavoitteena oli selvittää simulointien avulla tehtävien muutosten vaikutuksia moottorin kampi- ja venttiilikoneiston toimintaan. Lisäksi simulointien avulla suunniteltiin moottorin ahtojärjestelmän mitoitusta. Diplomityö sisältää myös kirjallisuustutkimuksen aikaisemmin muualla maailmalla rakennetuista optisista tutkimusmoottoreista ja niiden tyypillisimmistä rakenneratkaisuista. Simuloinneissa käytettiin Gamma Technologies -yrityksen valmistamaa GT-SUITE -simulointiohjelmistoa. Kampikoneiston simuloinnit on tehty GT-CRANK -ohjelmalla, venttiilikoneiston simuloinnit GT-VTRAIN -ohjelmalla ja ahtojärjestelmän simuloinnit GT-POWER -ohjelmalla. Saatujen tulosten mukaan kampi- ja venttiilikoneiston toiminnassa ei pitäisi ilmetä ongelmia, mikäli pysytään määritellyllä käyntinopeusalueella. Kampikoneiston simulointitulosten perusteella I-sylinterisellä kokoonpanolla vääntömomentin amplitudit kampiakselilla kasvavat kuitenkin huomattavasti, mikäli käyntinopeus nostetaan lähelle alkuperäisen moottorin maksimia. Ahtojärjestelmän simulointitulosten perusteella voitiin valita oletettua pienempi tasaajasäiliö. Tämä mahdollisti myös lyhyemmän imuputken käytön, mikä simulointitulosten perusteella on suunniteltua tutkimuskäyttöä ajatellen hyvä asia