Extensive reuse of soda-lime waste glass in fly ash-based geopolymers

The possibility of extensive incorporation of soda-lime waste glass in the synthesis of fly ash-based geopolymers was investigated. Using waste glass as silica supplier avoids the use of water glass solution as chemical activator. The influence of the addition of waste glass on the microstructure and strength of fly ash-based geopolymers was studied through microstructural and mechanical characterization. Leaching analyses were also carried out. The samples were developed changing the SiO2/Al2O3 molar ratio and the molarity of the sodium hydroxide solution used as alkaline activator. The results suggest that increasing the amount of waste glass as well as increasing the molarity of the solution lead to the formation of zeolite crystalline phases and an improvement of the mechanical strength. Leaching results confirmed that the new geopolymers have the capability to immobilize heavy metal ions

Automatic Recognition of Affective Body Movement in a Video Game Scenario

This study aims at recognizing the affective states of players from non-acted, non-repeated body movements in the context of a video game scenario. A motion capture system was used to collect the movements of the participants while playing a Nintendo Wii tennis game. Then, a combination of body movement features along with a machine learning technique was used in order to automatically recognize emotional states from body movements. Our system was then tested for its ability to generalize to new participants and to new body motion data using a sub-sampling validation technique. To train and evaluate our system, online evaluation surveys were created using the body movements collected from the motion capture system and human observers were recruited to classify them into affective categories. The results showed that observer agreement levels are above chance level and the automatic recognition system achieved recognition rates comparable to the observers' benchmark. © 2012 ICST Institute for Computer Science, Social Informatics and Telecommunications Engineering

Medium chain length polyhydroxyalkanoates, promising new biomedical materials for the future

Medium chain length polyhydroxyalkanoates, mcl-PHAs (C6–C14 carbon atoms), are polyesters of hydroxyalkanoates produced mainly by fluorescent Pseudomonads under unbalanced growth conditions. These mcl-PHAs which can be produced using renewable resources are biocompatible, biodegradable and thermoprocessable. They have low crystallinity, low glass transition temperature, low tensile strength and high elongation to break, making them elastomeric polymers. Mcl-PHAs and their copolymers are suitable for a range of biomedical applications where flexible biomaterials are required, such as heart valves and other cardiovascular applications as well as matrices for controlled drug delivery. Mcl-PHAs are more structurally diverse than short chain length PHAs and hence can be more readily tailored for specific applications. Composites have also been fabricated using mcl-PHAs and their copolymers, such as poly (3-hydroxyoctanoate) [P(3HO)] combined with single walled carbon nanotubes and poly(3-hydroxbutyrate-co-3-hydroxyhexanoate) [P(3HB-co-3HHx)] combined with hydroxyapatite. Because of these attractive properties of biodegradability, biocompatibility and tailorability, Mcl-PHAs and their composites are being increasingly used for biomedical applications. However, studies remain limited mainly to P(3HO) and the copolymer P(3HB-co-3HHx), which are the only mcl-PHAs available in large quantities. In this review we have consolidated current knowledge on the properties and biomedical applications of these elastomeric mcl-PHAs, their copolymers and their composites

Carbon nanotube-reinforced hydroxyapatite coatings on metallic implants using electrophoretic deposition

Electrophoretic deposition (EPD) has been demonstrated to be a convenient processing technique to fabricate composite ceramic coatings containing ordered arrays of carbon nanotubes. In this investigation, EPD was used to coat Ti6Al4V medical implants with hydroxyapatite (HA) layers reinforced with surface functionalized multi-walled carbon nanotubes (MWCNTs). The functionalization of MWCNTs by treating them with an acid mixture was successfully achieved in order to create functional groups on the MWCNT surfaces enabling them to be homogeneously dispersed in water. The surface treatment was also used to induce the adsorption of HA nanoparticles on MWCNT surfaces. Some critical issues, such as microcracking and peeling of HA layers after EPD, were effectively solved by the use of MWCNTs

Composite polymer-bioceramic scaffolds with drug delivery capability for bone tissue engineering

Next-generation scaffolds for bone tissue engineering (BTE) should exhibit the appropriate combination of mechanical support and morphological guidance for cell proliferation and attachment while at the same time serving as matrices for sustained delivery of therapeutic drugs and/or biomolecular signals, such as growth factors. Drug delivery from BTE scaffolds to induce the formation of functional tissues, which may need to vary temporally and spatially, represents a versatile approach to manipulating the local environment for directing cell function and/or to treat common bone diseases or local infection. In addition, drug delivery from BTE is proposed to either increase the expression of tissue inductive factors or to block the expression of others factors that could inhibit bone tissue formation. Composite scaffolds which combine biopolymers and bioactive ceramics in mechanically competent 3D structures, including also organic--inorganic hybrids, are being widely developed for BTE, where the affinity and interaction between biomaterials and therapeutic drugs or biomolecular signals play a decisive role in controlling the release rate.This review covers current developments and applications of 3D composite scaffolds for BTE which exhibit the added capability of controlled delivery of therapeutic drugs or growth factors. A summary of drugs and biomolecules incorporated in composite scaffolds and approaches developed to combine biopolymers and bioceramics in composites for drug delivery systems for BTE is presented. Special attention is given to identify the main challenges and unmet needs of current designs and technologies for developing such multifunctional 3D composite scaffolds for BTE. One of the major challenges for developing composite scaffolds for BTE is the incorporation of a drug delivery function of sufficient complexity to be able to induce the release patterns that may be necessary for effective osseointegration, vascularization and bone regeneration. Loading 3D scaffolds with different biomolecular agents should produce a codelivery system with different, predetermined release profiles. It is also envisaged that the number of relevant bioactive agents that can be loaded onto scaffolds will be increased, whilst the composite scaffold design should exploit synergistically the different degradation profiles of the organic and inorganic components.Fil: Mouriño, Viviana Silvia Lourdes. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Tecnología Farmacéutica; Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentina; Universitat Erlangen-Nuremberg; Alemania;Fil: Cattalini, Juan Pablo. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentina; Universitat Erlangen-Nuremberg; Alemania;Fil: Roether, J.. Universitat Erlangen-Nuremberg; Alemania;Fil: Dubey, P.. Universitat Erlangen-Nuremberg; Alemania;Fil: Roy, I.. Universitat Erlangen-Nuremberg; Alemania;Fil: Boccaccini, A. R.. Universitat Erlangen-Nuremberg; Alemania

Analysis of porosity in NiTi SMA's changed by secondary pulse electric current treatment by means of ultra small angle scattering and micro-computed tomography

Porous NiTi samples were produced by two different techniques, Mechanical Alloying & Hot Pressing (MA&HP) and Reaction Synthesis (RS), followed by secondary Pulse Electric Current (PEC) treatment. The samples were analyzed by Ultra Small Angle Neutron Scattering and Computed Microtomography before and after the secondary treatment in order to investigate porosity of the samples. For the samples produced by MA&HP, PEC treatment does not cause any changes in pore size distribution for smaller pores (i.e.<10 μm). For bigger pores, however, treatment leads to a decrease of the pore volume along with the reduction of the amount of pores. In samples processed by RS, PEC treatment led to a decrease in pore dimensions of smaller pores (up to 10 μm), while for larger pores PEC treatment resulted in an increase in pore dimensions. Thus, the influence of secondary PEC treatment on the porosity of NiTi samples produced by the two different techniques could be confirmed and compared. Due to the pioneering character of the present work, further studies are required before using PEC treatment in future for porosity modification in a controlled manner.Peer reviewe

Development and in vitro characterisation of novel bioresorbable and bioactive composite materials based on polylactide foams and Bioglass (R) for tissue engineering applications

Bioactive and bioresorbable composite materials were fabricated using macroporous poly(DL-lactide) (PDLLA) foams coated with and impregnated by bioactive glass (Bioglass®) particles. Stable and homogeneous Bioglasss coatings on the surface of PDLLA foams as well as infiltration of Bioglass® particles throughout the porous network were achieved using a slurry-dipping technique in conjunction with pre-treatment of the foams in ethanol. The quality of the bioactive glass coatings was reproducible in terms of thickness and microstructure. Additionally, electrophoretic deposition was investigated as an alternative method for the fabrication of PDLLA foam/Bioglass® composite materials. In vitro studies in simulated body fluid (SBF) were performed to study the formation of hydroxyapatite (HA) on the surface of PDLLA/Bioglass® composites. SEM analysis showed that the HA layer thickness rapidly increased with increasing time in SBF. The high bioactivity of the PDLLA foam/Bioglasss composites indicates the potential of the materials for use as bioactive, resorbable scaffolds in bone tissue engineering

Livskvalitet før og etter et opphold ved Valnesfjord helsesportssenter

A novel nanocomposite material combining the biocompatible, elastomeric, natural, biodegradable homopolymer poly(3-hydroxyoctanoate) (P(3HO)) with hemostatic and antibacterial bioactive glass nanoparticles (n-BG) was developed as a matrix for skin related applications. P(3HO) is a unique member of the family of natural polyhydroxyalkanoate biopolymers. The P(3HO)/n-BG composite films were fabricated using the solvent casting method. Microstructural studies revealed n-BG particles both embedded in the matrix and deposited on the surface, which introduced nanotopography and increased its hydrophilicity. The composite exhibited an increase in the Young’s modulus when compared to the control, yet maintained flexible elastomeric properties. These changes in the surface topography and chemistry of the composite system led to an increase of protein adsorption and cytocompatibility for the seeded human keratinocyte cell line. The results from this study demonstrated that the fabricated P(3HO)/n-BG composite system is a promising novel matrix material with potential applications in skin tissue engineering and wound healing