Bone remodeling I: theory of adaptive elasticity

A thermomechanical continuum theory involving a chemical reaction and mass transfer between two constituents is developed here as a model for bone remodeling. Bone remodeling is a collective term for the continual processes of growth, reinforcement and resorbtion which occur in living bone. The resulting theory describes an elastic material which adapts its structure to applied loading.

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Zusammenfassung Eine Thermo-mechanische kontinuum Theorie als Modell für die Knochenrekonstrucktion wird entwickelt, die eine chemische Reaktion und einen Massentransport zwischen zwei Komponenten behandelt. Knochenrekonstruktion ist ein Sammelbegriff für die kontinuierlichen Prozesse des Wachsens, der Verstärkung und des Abbaus wie sie im lebenden Knochen auftreten. Die Theorie beschreibt ein elastisches Material, das sich in der Form der Belastung anpasst.

     

Syntheses and reactions of optically active alpha-aminoallenylstannanes

Lithiation/stannylation of optically active N-propargyloxazolidinones produced optically active alpha-oxazolidinonylallenylstannanes. Reaction of these with aldehydes in the presence of BF(3).OEt(2) produced beta-hydroxypropargylamines with high syn diastereoselectivity and ee. These were converted to gamma-hydroxy-beta-amino acids by oxidative cleavage of the alkyne.     

ISO compliant laboratory quality systems and incident monitoring improve the implementation of laboratory information systems

Quality systems can provide a means of measuring the rate of occurrence of defined incidents and non-conformities. We have studied the application of laboratory quality systems to monitoring the implementation of laboratory information systems (LIS) in two similar size tertiary hospital pathology laboratories in Australia. At one site, one department implemented a quality system accredited to ISO 9001–1987 and ISO 9001–1994 while the rest of the organisation did not have a formal quality system; this site implemented the Cerner PathNet LIS. At the other site, the organisation was in the process of implementing ISO/IEC Guide 25–1990 and ISO/IEC 17025–1999; this site implemented the PJACC AUSLAB LIS. The rate of quality system incidents and non-conformities was used to track the progress of implementation of the LIS. We found that different quality systems appeared equally useful in monitoring the rate of occurrence of incidents. However, the presence of a formal quality system greatly improved the proportion of incidents that could be investigated and resolved at root cause level. Incident monitoring, as part of a formal quality system, proved to be a useful tool in monitoring and managing the implementation of these LIS. Received: 4 August 2001 Accepted: 21 March 2002     

Synthesis of 4'-methyl and 4'-cyano carbocyclic 2',3'-didehydro nucleoside analogues via 1,4-addition to substituted cyclopentenones

Carbocyclic 4'-methyl and 4'-cyano nucleoside analogues were synthesized using the Michael reaction to introduce the 4'-substituent and Pd-catalyzed allylic substitution to introduce the nucleoside base. Use of both the desired beta- and undesired alpha-1'-carbonate diastereomers in the Pd-catalyzed substitution was demonstrated in principle by epimerization of the alpha-diastereomer and kinetic diastereodifferentiation of a 1:1 alpha/beta mixture of 1'-carbonates.