Enzymatic kinetic resolution of organochalcogenides in supercritical CO(2)

1-(Phenylthio)-, 1-(phenylseleno)- and 1-(phenyltelluro)-propan-2-ol were efficiently resolved by CAL-B in sc-CO(2). (C) 2011 Elsevier Ltd. All rights reserved.

Kinetic resolution of iodophenylethanols by Candida antarctica lipase and their application for the synthesis of chiral biphenyl compounds

The kinetic resolution of (+/-)-iodophenylethanols was carried out using lipase from Candida antarctica and in some cases the enantiomeric excesses were high (up to >98%). Enantiomerically enriched (S)-iodophenylethanols produced by the enzymatic resolution process were used in the synthesis of chiral biphenyl compounds by the Suzuki reaction with good yields (63-65%). (C) 2010 Elsevier Ltd. All rights reserved.

Limits to phase resolution in matter-wave interferometry

We study the quantum dynamics of a two-mode Bose-Einstein condensate in a time-dependent symmetric double-well potential using analytical and numerical methods. The effects of internal degrees of freedom on the visibility of interference fringes during a stage of ballistic expansion are investigated varying particle number, nonlinear interaction sign and strength, as well as tunneling coupling. Expressions for the phase resolution are derived and the possible enhancement due to squeezing is discussed. In particular, the role of the superfluid-Mott insulator crossover and its analog for attractive interactions is recognized.

High-resolution terrestrial permian-triassic eventostratigraphic boundary in western Guizhou and eastern Yunnan, southwestern China

The adjoining area of western Guizhou and eastern Yunnan Provinces in southwest China is an ideal place to investigate the feasibility of correlating marine and nonmarine Permian–Triassic boundary (PTB) sequences, as it contains outcrop sections of shallow marine, marginal marine (or paralic), and terrestrial PTB sections, all in close geographic proximity. This paper documents for the first time multiple stratigraphic data from several well-preserved terrestrial PTB sections in the area and attempts to use these data to define, locate, and correlate the PTB in the area. A study of the spores and pollen and vegetation types across the terrestrial PTB sections in the study area suggests three distinct evolutionary stages across the boundary: Stage 1 (Xuanwei Formation) is characterised by Late Permian or Paleozoic-type ferns and pteridosperms (85.0%), with a few gymnosperms (15.0%); stage 2 is marked by an abrupt drop of sporopollen elements of Late Permian aspects, coupled with the appearance of fungal spores and limited Early Triassic palynomorphs; stage 3 (top Xuanwei Formation and Kayitou Formation) is dominated by gymnosperm pollen (58.8%) of clearly Early Triassic aspect, although still retaining limited ferns and pteridosperms. The three biotic stages seem to well correspond with the changing trend of the δ13Corg curves from the same sections, which is characterized by a sharp drop just before the PTB, followed by a short term partial recovery across the boundary, and then succeeded by a gradual decline after the PTB in the Early Triassic. Combining evidence from eventostratigraphic (i.e., the succession of boundary clay beds), biostratigraphic (using both macroplants and palynomorphs), and chemostratigraphic (i.e., organic carbon isotope excursion signals), we propose that a high-resolution PTB succession, closely correlatable to its marine counterpart at the Meishan section in eastern China, is recognisable at the terrestrial PTB sections in the western Guizhou–eastern Yunnan area in southwest China.

Monodic temporal resolution

Until recently, First-Order Temporal Logic (FOTL) has been only partially understood. While it is well known that the full logic has no finite axiomatisation, a more detailed analysis of fragments of the logic was not previously available. However, a breakthrough by Hodkinson et al., identifying a finitely axiomatisable fragment, termed the monodic fragment, has led to improved understanding of FOTL. Yet, in order to utilise these theoretical advances, it is important to have appropriate proof techniques for this monodic fragment.In this paper, we modify and extend the clausal temporal resolution technique, originally developed for propositional temporal logics, to enable its use in such monodic fragments. We develop a specific normal form for monodic formulae in FOTL, and provide a complete resolution calculus for formulae in this form. Not only is this clausal resolution technique useful as a practical proof technique for certain monodic classes, but the use of this approach provides us with increased understanding of the monodic fragment. In particular, we here show how several features of monodic FOTL can be established as corollaries of the completeness result for the clausal temporal resolution method. These include definitions of new decidable monodic classes, simplification of existing monodic classes by reductions, and completeness of clausal temporal resolution in the case of monodic logics with expanding domains, a case with much significance in both theory and practice.