A synthesis of crambescidin 359

A potentially biomimetic synthesis of the guanidine-containing marine natural product crambescidin 359 via a double Michael addition of guanidine to a suitably functionalised bis-enone is reported.     

Studies of prereactions during MOVPE growth of wide band-gap II/VI semiconductors: the effect of pyridine upon the gas-phase reactions between H2S and Me2Zn

The effect of pyridine addition upon the gas-phase reactions of hydrogen sulphide (H₂S) with dimethylzinc (Me₂Zn) in the presence of pyridine has been investigated and compared with results from reactions of H₂S with Me₂Cd. The deposits of ZnS which form have been analysed and consist of particles in the nanocrystalline size range of mainly the hexagonal phase. The average particle size within the deposits depends on both the concentration of pyridine in the gas phase and the temperature at which the reactants are mixed. Pyridine may bind through the lone pair of the nitrogen to surface metal atoms of growing particles, inhibiting further growth of the particle.     

Mapping Surgery To Analysis III: Exact Sequences

Using the constructions of the preceding two papers, we construct a natural transformation (after inverting 2) from the Browder-Novikov-Sullivan-Wall surgery exact sequence of a compact manifold to a certain exact sequence of C ^*-algebra K-theory groups. Mathematics Subject Classification (1991): 19J25, 19K99     

Mapping Surgery to Analysis I: Analytic Signatures

We develop the theory of analytically controlled Poincaré complexes over C ^*-algebras. We associate a signature in C ^*-algebra K-theory to such a complex, and we show that it is invariant under bordism and homotopy. The authors were supported in part by NSF Grant DMS-0100464.     

Thermoelastic waves in a constrained isotropic plate: incompressibility at uniform temperature

Thermoelastic waves are investigated which propagate throughan isotropic plate which is constrained to be incompressibleat uniform temperature. This is an example of a deformation–temperatureconstraint, also known as a strain–temperature constraint.The boundaries of the plate are taken to be traction free andeither isothermal or insulated. Dispersion relations are derivedand expanded asymptotically in the long-wave low-frequency limit.The short-wave limit is also discussed. The higher modes areinvestigated numerically. Graphical comparison with the unconstrainedmaterial is also presented.     

Bile UPLC-MS fingerprinting and bile acid fluxes during human liver transplantation

Bile flow restoration is a crucial step in the recovery process post transplantation of the liver. Here, metabolic trajectories based on changes in bile secretion - a known marker of functionality - have been utilised as an approach for discovering bile fluxes during transplantation. A total of ten liver transplants were monitored and from these 68 bile samples from both donors and recipients were collected and analysed using ultra-performance LC-MS in combination with multivariate statistical analysis. Based on the principal component scores constructed from the total bile fingerprint, differentiation of the bile acid concentrations before and after transplantation was detected. A trend was also observed, by constructing metabolic trajectories, whereby the post-transplant profiles approached the position of pre-transplant profiles within 30-60?min of the restoration of bile secretion function. The ten major conjugated bile acid salts were measured and a significant increase in concentrations of taurocholic acid and taurochenodeoxycholic acid were seen after transplantation. In addition, the ratios of secondary bile acids detected in gall bladder and hepatic bile were measured before and after transplantation. This study suggests that bile acid ratios in the donor liver at the pre-transplant and post-transplant stage may be important and that profiling of secreted bile after transplantation may aid clinical assessment and progress post-transplantation.