Imidazolium-functionalized bipyridine derivatives: a promising family of ligands for catalytical Rh(0) colloids

A new imidazolium-monofunctionalized bipyridine ligand has been synthesized and efficiently used as a protective agent for Rh(0) nanoparticles. Preliminary results in arene hydrogenation have been obtained.     

Spin quantum bit with ferromagnetic contacts for circuit QED

We theoretically propose a scheme for a spin quantum bit based on a double quantum dot contacted to ferromagnetic elements. Interface exchange effects enable an all electric manipulation of the spin and a switchable strong coupling to a superconducting coplanar waveguide cavity. Our setup does not rely on any specific band structure and can in principle be realized with many different types of nanoconductors. This allows us to envision on-chip single spin manipulation and readout using cavity QED techniques.     

Large time behavior and asymptotic stability of the 2D Euler and linearized Euler equations

We study the asymptotic behavior and the asymptotic stability of the 2D Euler equations and of the 2D linearized Euler equations close to parallel flows. We focus on flows with spectrally stable profiles U(y) and with stationary streamlines y=y₀ (such that U^′(y₀)=0), a case that has not been studied previously. We describe a new dynamical phenomenon: the depletion of the vorticity at the stationary streamlines. An unexpected consequence is that the velocity decays for large times with power laws, similarly to what happens in the case of the Orr mechanism for base flows without stationary streamlines. The asymptotic behaviors of velocity and the asymptotic profiles of vorticity are theoretically predicted and compared with direct numerical simulations. We argue on the asymptotic stability of this ensemble of flow profiles even in the absence of any dissipative mechanisms.     

26Th ssrl users conference

The 2004 CHESS User Meeting was held on June 18 and 19, 2004, on the campus of Cornell University in Ithaca, New York. The meeting included the dedication ceremony for CHESS's latest addition, G-line. G-line was also featured in this year's CHESS workshop. In order to accommodate the dedication cere-mony in the afternoon of the first day, the user meeting followed a condensed format: The directors' reports were kept to a minimum and staff reports were presented as posters within the general poster session.

The User Meeting was opened by User Committee member Lois Pollack (Cornell). The first speaker was CHESS director Sol Gruner, who presented an overview of the achievements in the past running period, in particular the new mode of dedicated CHESS operation whereby dedicated X-ray production and high energy physics (HEP) interleave use of the storage ring.     

Sources of primary production to Arctic bivalves identified using amino acid stable carbon isotope fingerprinting*

ABSTRACT

Benthic invertebrates are a crucial trophic link in Arctic marine food webs. However, estimates of the contribution of different primary production sources sustaining these organisms are not well characterised. We measured the stable carbon isotope values (δ¹³C) of essential amino acids (EAAs) in muscle tissue from two common bivalve genera (Macoma spp. and Astarte spp.) collected in Hanna Shoal in the northeastern Chukchi Sea. Mixing models comparing the δ¹³C_EAA fingerprints of the bivalves to a suite of primary production endmembers revealed relatively high contributions of EAAs from phytoplankton and bacteria in both species. We also examined whether δ¹³C_EAA fingerprints could be produced from the EAAs preserved in bivalve shells, which could allow primary production sources to be estimated from ancient bivalve shells. The δ¹³C_EAA fingerprints from a suite of paired modern bivalve shells and muscle from Macoma calcarea from across the Chukchi Sea revealed a correspondence between the estimates of the dominant primary production source of EAAs derived from analyses of these two tissue types. Our findings indicate that δ¹³C_EAA fingerprinting of marine bivalves can be used to examine dominant organic matter sources in the Arctic marine benthos in recent years as well as in deeper time.     

Cosine Modulated HSQC: A Rapid Determination of JHNHα Scalar Couplings in N-labeled Proteins

A two-dimensional HSQC-based NMR method, ¹⁵N-COSMO-HSQC, is presented for the rapid determination of homonuclear ³J_HNHα couplings in ¹⁵N-labeled proteins in solution. Scalar couplings are extracted by comparing the intensity of two separate datasets recorded with and without decoupling of the ³J_HNHα during a preparation period. The scalar couplings are introduced through a cosine modulation of the peak intensities. The experiment relies on a BIRD sandwich to selectively invert all amide protons H^N and is very simple to implement. ³J_HNHα couplings were determined using both the ¹⁵N-COSMO-HSQC and quantitative-J on ¹⁵N-labeled chemokine RANTES. The two experiments show well-correlated values.