Performance of calcium deficient hydroxyapatite-polyglycolic acid composites: An in vitro study

The strategic incorporation of bioresorbable polymeric additives to calcium-deficient hydroxyapatite cement may provide short-term structural reinforcement and modify the modulus to closer match bone. The longer-term resorption properties may also be improved, creating pathways for bone in-growth. The aim of this study was to investigate the resorption process of a calcium phosphate cement system containing either in polyglycolic acid tri-methylene carbonate particles or polyglycolic acid fibres. This was achieved by in vitro aging in physiological conditions (phosphate buffered solution at 37°C) over 12 weeks. The unreinforced CPC exhibited an increase in compressive strength at 12 weeks, however catastrophic failure was observed above a critical loading. The fracture behaviour of cement was improved by the incorporation of PGA fibres; the cement retained its cohesive structure after critical loading. Gravimetric analysis and scanning electron microscopy showed a large proportion of the fibres had resorbed after 12 weeks allowing for the increased cement porosity, which could facilitate cell infiltration and faster integration of natural bone. Incorporating the particulate additives in the cement did not provide any mechanism for mechanical property augmentation or did not demonstrate any appreciable level of resorption after 12 weeks.

Enforcing Member State Compliance with EU Environmental Law: A Critical Evaulation of the Use of Financial Penalties

The 1993 Treaty on European Union finally closed a legal vacuum in
EU law, by giving the Court the power to impose financial penalties to
enforce compliance with its judgments. Today, this power is found
within Article 260(2) of the Treaty on the Functioning of the
European Union. Drawing upon case law, this article examines the
role that the Court’s enforcement powers have played in relation to
EU environmental law. It argues that EU law has yet to make full use
of their potential. The article commences with the Commission and
questions whether it has sufficient resources to carry out its functions
under Article 260(2). The article also examines the ongoing problem of
Member State delay in complying with Court judgments and the
weight given to environmental considerations in the Court’s decision
making on financial penalties. The article concludes by examining the
implications of the Lisbon Treaty.