INTRODUCTION: Porous titanium is used as implant material because of its high specific strength, bone-like stiffness, biocompatibility and good bone cell ingrowth provided that the open pores have sizes between 100 μm and 500μm. Powder metallurgy has been successfully used to produce titanium foams by using the space holder method [1-3]. Recently, Ti grade 4 has been obtained by powder injection moulding (PIM) of titanium hydride, which is cheaper and less reactive than pure titanium [4]. The feasibility of a novel route combining TiH2 and space holders to produce porous titanium is explored in this work.

Titanium alloys containing beta stabilising elements such as Nb, Zr and Ta are particularly promising as implant materials because of their excellent combination of low modulus, high strength, corrosion resistance and biocompatibility. A low elastic modulus is important for implants to avoid stress shielding and associated bone resorption. The difficulty of producing complex shapes of these alloys by conventional methods makes metal injection moulding (MIM) attractive. Ti-17Nb alloy parts with densities 94% of theoretical have been produced by MIM of a feedstock based on blended elemental powders. Scanning electron microscopy reveals a typical alpha-beta Widmanstatten microstructure with a precipitated a phase layer along the grain boundaries. The parts exhibit an ultimate tensile strength of 768 MPa and a plastic elongation of over 5%. The modulus of elasticity, about 84 GPa, is more than 20% lower than that of cp Ti and Ti-6Al-4V.

Enzyme catalysis with minimal ionic liquid quantities improves reaction rates, stereoselectivity and enables solvent-free processing. In particular the widely used lipases combine well with many ionic liquids. Demonstrated applications are racemate separation, esterification and glycerolysis. Minimal solvent processing is also an alternative to sluggish solvent-free catalysis. The method allows simplified down-stream processing, as only traces of ionic liquids have to be removed.

Microcalorimetry and cloud point extrapolation indicate a lower critical solution temperature of 216 °C for poly(N,N-dimethylacrylamide) (PDMA). This is the highest phase-transition temperature in the poly(N,N-dialkylacrylamide) series. Cloud points were recorded from electrolyte solutions made of Na3PO4, CaCO3, (NH4)2SO4 and KOH. These measurements were realized below and beyond the boiling point of water. The hydrolytic properties of PDMA in superheated water (200 °C) were examined and verified using 1H NMR analysis. The knowledge of the phase-transition temperature of pure PDMA is of interest, as it is often a constituent of smart copolymers, to adjust the responsiveness to a desired temperature threshold. Copyright © 2011 Society of Chemical Industry

A homologous series of biosurfactants has been synthesized by a novel sustainable biotransformation technique and compared with three other enzymatic processes. 6-O-Alkanoyl-methyl-α-D-glucopyranosides were obtained by lipase mediated esterification of methyl-α-D-glucopyranoside with capric acid C10:0, lauric acid C12:0, myristic acid C14:0, palmitic acid C16:0, and oleic acid C18:1. Solvent free transformations were compared with the use of ionic liquids and organic solvents. The lipase from Candida antarctica B, immobilized on macroporous acrylic acid beads (Novozyme 435), was employed either untreated or coated with small amounts of ionic liquids. This resulted in superior efficiencies (80%) with 1-butyl-4-methylpyridine hexafluorophosphate [4bmpy][PF6] and broader substrate tolerance in comparison to solvent free transformation. The results show a positive correlation with increasing polarity of the ionic liquids used as liquid film-coating, which was in opposition to the use of the same ionic liquid as solvent. The analysis of the ionic liquid film coated catalyst carriers was performed by optical and scanning electron microscopy (SEM).

An imaging method has been developed to examine thermo responsive polymer coagulates by optical and electron microscopy. Poly-N-isopropylacrylamide (PNIPAM), poly-N-dimethylacrylamide (PDMAM) and a 1:1 PNIPAM–PDMAM copolymer were encapsulated in a gelatin matrix as coagulates above the lower critical solution temperature (LCST), and subsequently examined by optical and electron microscopy. The linear macromolecules PNIPAM and PDMAM were synthesized by chain transfer polymerization with mercaptopropionic acid (3-MPA) as chain transfer reagent. The resulting polymers have an average molar mass of ∼1800g/mol and low polydispersity. The LCST of thermo responsive polymers is defined in pure water but can also be stimulated at lower than the phase transition temperature employing electrolytes containing inorganic salts such as (NH4)2SO4. Under such conditions the polymers show the typical thermo responsive phase transfer property in form of a visible clouding point. Gelatin was used to maintain this biphasic state by slowly adding water-softened gelatin sheets at a temperature above the LCST, followed by cooling to 3°C in order to induce gelation. Examination of the gelatin–coagulate matrices by optical and electronic microscopy showed that PNIPAM and its copolymer (PNIPAM/PDMAM 1:1) are entrapped as globular spheres and clusters of spheres. In comparison pure PDMAM, even if it shows a clouding point, does not form typical LCST coagulates. With PNIPAM and the copolymer, micro globule formation is also possible with slow gelatin formation, without first provoking an LCST. In this particular case, the phase transition, or entropic demixing of the polymers respectively, are induced in this case by water absorption of the gelatin matrix.