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The viability of using monomeric analogs of polyureas as ligands in asymmetric catalysis and hydride transfer reduction was examined. Specifically, diureas from diamines (1R,2R)-1,2-diaminocyclohexane and N,N'-dimethyl-1,2-diphenylethanediamine as well as optically pure (R)-(+) and (S)-(-)-alpha-methylbenzyl isocyanates were used in the asymmetric reduction of aromatic ketones such as acetophenone and propiophenone.

ABSTRACT The rheological behavior of two series of aliphatic hyperbranched (HB) polyesters, based on 2,2-bis(hydroxymethyl)propionic acid (bis-MPA) and di-trimethylol propane (Di-TMP) as a tetrafunctional core, was studied. The effect of the size (pseudo-generation number, from second to eight) and structure on the melt rheological properties was investigated for a series of hydroxyl-terminated HB polyesters. In addition, the influence of the nature and degree of modification of the terminal OH groups in a series of fourth-generation polyesters end-capped with short and long alkyl chains and some aryl groups on the rheological properties was analyzed. The time-temperature superposition procedure was applied for the construction of master curves and for the analysis of the rheological properties of HB polyesters. The data obtained from WLF analysis of the HB polyesters showed that the values of the thermal coefficient of expansion of free volume αf and the fractional free volume at the glass transition temperature, fg, increase with increasing size of the HB polyesters. It was shown that the modified HB polyesters exhibited lower Tg and TG′= G″ temperatures, above which viscous became dominant over elastic behavior. From an analysis of the master curves of the modified HB polyesters, it was observed that with increasing degree of modification, both storage and loss modules and complex dynamic viscosity and apparent energy for viscoelastic relaxation decrease, because of reduced intermolecular hydrogen interactions. They do not exhibit a plateau of rubbery behavior, which confirms that no entanglements are present and that the molar masses are below the critical molar mass. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41479. [ABSTRACT FROM AUTHOR]

Aim: Patients undergoing bypass graft placement in the lower limb are often entered into a graft surveillance programme using duplex scanning. The aim of this programme is to identify stenoses in vein grafts before they become symptomatic and treat these by angioplasty or surgery, thus prolonging the patency of the graft. This paper aims at reporting on the progress and viability of this programme at Mater Dei Hospital, Malta. Method: Infrainguinal bypass grafts carried out between July 2007 and May 2009 were enrolled. Scanning starts during the patient's in-hospital stay at one week post-operation. It is then scheduled at 6 weeks, 3 months, 6 months, 12 months, 18 months, 24 months, and yearly afterwards. When a significant stenosis is encountered, the patient is referred for angioplasty. Surgery would be considered in cases when angioplasty is not an option. Results: During this period 56 patients were recruited. At one week post-op the patency rate was 100%. At 6 months the primary unassisted patency was 77.5% while the primary assisted patency was 87.5%. At 12 months the primary unassisted patency was 50% while the primary assisted patency was 77%. Secondary patency rates at 6 and 12 months were 95% and 82% respectively. Conclusion: The graft surveillance programme ensures that any problem detected in the post-operative period is dealt with as soon as possible. The study shows that this programme is being effective in that assisted rates (i.e. after angioplasty or surgery) are better than unassisted rates. [ABSTRACT FROM AUTHOR]