Search results for "FINANCE"

Dragging a Polymer Chain into a Nanotube and Subsequent Release

2008

We present a scaling theory and Monte Carlo (MC) simulation results for a flexible polymer chain slowly dragged by one end into a nanotube. We also describe the situation when the completely confined chain is released and gradually leaves the tube. MC simulations were performed for a self-avoiding lattice model with a biased chain growth algorithm, the pruned-enriched Rosenbluth method. The nanotube is a long channel opened at one end and its diameter $D$ is much smaller than the size of the polymer coil in solution. We analyze the following characteristics as functions of the chain end position $x$ inside the tube: the free energy of confinement, the average end-to-end distance, the averag…

O2‐04‐04: The metalloprotease meprin beta generates amino‐terminally truncated beta‐amyloid peptide species

2012

Diastereoselective synthesis of fluorinated, seven-membered beta-amino acid derivatives via ring-closing metathesis.

2003

[reaction: see text] Cis and trans seven-membered gamma,gamma-difluorinated beta-amino acid derivatives (III) have been prepared with a sequence that starts with imidoyl halides (I), which are condensed with suitable ester enolates to give intermediates (II). These, in turn, can be cyclized by means of a ring-closing olefin metathesis reaction and the product stereoselectively reduced to yield compounds (III) in good overall yields.

Structure and dynamics of thin polymer films: a case study with the bond-fluctuation model

2002

Abstract This paper reports Monte Carlo simulation results of a polymer melt of short, non-entangled chains which are embedded between two impenetrable walls. The melt is simulated by the bond-fluctuation lattice model under athermal conditions, i.e. only excluded volume interactions between the monomers and between the monomers and the walls are taken into account. In the simulations, the wall separation is varied from about one to about 15 times the bulk radius of gyration R g . The confinement influences both static and dynamic properties of the films: Chains close to the walls preferentially orient parallel to it. This parallel orientation decays with increasing distances from the wall …

Simulation of Copolymer Bottle-Brushes

2007

The structure of bottle-brush polymers with a rigid backbone and flexible side chains is studied in three dimensions, varying the grafting density, the side chain length, and the solvent quality. Some preliminary results of theoretical scaling considerations for one-component bottle-brush polymers in a good solvent are compared with Monte Carlo simulations of a simple lattice model. For the simulations a variant of the pruned-enriched Rosenbluth method (PERM) allowing for simultaneous growth of all side chains in the Monte Carlo sampling is employed. For a symmetrical binary (A,B) bottle-brush polymer, where two types (A,B) of flexible side chains are grafted with one chain end to the backb…

Asymmetric synthesis of fluorinated cyclic beta-amino acid derivatives through cross metathesis.

2006

The asymmetric synthesis of several fluorinated cis-2-aminocycloalkane carboxylic acids (cis-2-ACACs) with a cross metathesis (CM) reaction as the key step has been carried out, constituting the first time a metathesis protocol has been undertaken with fluorinated imidoyl chlorides. Subsequent chemoselective hydrogenation of the olefin moiety, Dieckmann condensation, and stereoselective reduction of the iminic double bond afforded the corresponding beta-amino esters with several ring sizes. The asymmetric version of the process was achieved by using (-)-8-phenylmenthol as a chiral auxiliary.

ChemInform Abstract: Carbohydrates as Chiral Templates in the Stereoselective Synthesis of . beta.-Amino Acids

2010

An efficient synthesis of uracil derivatives from 2-alkyl-Δ2-oxazolines and nitriles

2008

An efficient and convenient synthesis of new fluorinated and non-fluorinated uracils is described herein. The condensation of nitriles with enolates generated from 2-alkyl-Δ 2 -oxazolines (I) affords fluorinated β-enamino acid derivatives, which react with triphosgene to give an isomeric mixture of oxazolopyrimidinones. These can then be easily transformed into a single C-6 pyrimidindione derivative through reaction with a suitable nucleophile.

Stereocontrolled approach to quinuclidine derivatives

1998

Abstract Asymmetric Michael-type cyclization of chiral enamino ester (S)-7 furnished the quinuclidinone derivative (3R, 4S)-5, with a high degree of stereoselectivity.

Volatility transmission in the CO<inf>2</inf> and energy markets

2009

The main consequence of the launch, in 2005, of the European Union Emission Trading Scheme (EU ETS) has been the establishment of a price for carbon emissions. Thus, major energy producers in Europe are now aware of the impact of their polluting activities. The interest in analysing the carbon markets from a financial point of view has exponentially increased since the launch of the EU ETS. However, no research articles have focused their attention on the volatility transmission between CO 2 and energy markets. The aim of this paper is to fill this gap in the literature. Specifically, our particular interest is to examine whether or not conditional volatility is transmitted across those mar…