Delicious not siliceous: expanded carbohydrates as renewable separation media for column chromatography

Expansion of native corn starch produces a high surface area mesoporous material capable of acting as a novel stationary phase for separating various mixtures of compounds.     

Necessary and Sufficient Conditions to be an Eigenvalue for Linearly Recurrent Dynamical Cantor Systems

Necessary and sufficient conditions are given for linearly recurrentCantor dynamical systems to have measurable and continuous eigenfunctions.Also an example of a linearly recurrent system with a nontrivialKronecker factor and a trivial maximal equicontinuous factoris constructed explicitly.     

Exchange and correlation effects in electronic excitations of Cu(2)O

State-of-the-art theoretical methods fail in describing the optical absorption spectrum, band gap, and optical onset of Cu(2)O. We have extended a recently proposed self-consistent quasiparticle approach, based on the GW approximation, to the calculation of optical spectra, including excitonic effects. The band structure compares favorably with our present angle-resolved photoemission measurements. The excitonic effects based on these realistic band structure and screening provide a reliable optical absorption spectrum, which allows for a revised interpretation of its main structures.     

Signatures of short-range many-body effects in the dielectric function of silicon for finite momentum transfer

We present an investigation of the dynamic structure factor and of the dielectric function epsilonM(Q,omega) of the prototypical semiconductor silicon for finite momentum transfer, combining inelastic x-ray scattering experiments and ab initio calculations. In contrast with optical spectra, for finite momentum transfer time-dependent density-functional theory in the adiabatic local-density approximation together with lifetime broadening describes the physics of valence excitations correctly. Major structures in the spectra, governed by short-range crystal and exchange-correlation local-field effects, are strongly influenced by a mixing of transitions of positive and negative energies, in striking difference to spectra for vanishing momentum transfer. This mixing gives rise to a pronounced Fano asymmetry.     

Bimodal growth of Au on SrTiO3(001)

We have investigated the vapor phase growth of Au on SrTiO3(001)-(2 x 1) substrates by UHV scanning tunneling microscopy. Submonolayer (ML) coverages below 300 degrees C wet the surface as disordered metastable 2D islands. Beyond 0.75 ML fcc nanocrystals with a (111) interface are nucleated and ripen by dewetting the surrounding layer. Some multiply twinned fivefold symmetric clusters are also created. Above 400 degrees C dewetting occurs for all coverages and the surface is only populated by nanocrystals and fivefold clusters. A planar ground state configuration for small Au clusters and a higher interface energy for crystals than for wetted 2D ML films explains these results.     

Sterically non-hindering endocyclic ligands of the bi-isoquinoline family

Bi-isoquinoline can be used as a building block to prepare a new family of non-sterically hindering chelates, including a macrocyclic system; the endocyclic nature of the ligands has been confirmed by the X-ray structure of an octahedral tris-chelate iron(II) complex, which shows that the three chelates are easily accommodated in the coordination sphere of the metal in spite of their crescent shape.     

Galactose Oxidase models: 19F NMR as a powerful tool to study the solution chemistry of tripodal ligands in the presence of copper(II)

In copper(ii) complexes of tripodal ligands, the protonation state of the phenol moiety, and its position (axial vs. equatorial), are easily assessed by (19)F NMR.     

Mechanically controlled DNA extrusion from a palindromic sequence by single molecule micromanipulation

A magnetic tweezers setup is used to control both the stretching force and the relative linking number DeltaLk of a palindromic DNA molecule. We show here, in absence of divalent ions, that twisting negatively the molecule while stretching it at approximately 1 pN induces the formation of a cruciform DNA structure. Furthermore, once the cruciform DNA structure is formed, the extrusion of several kilo-base pairs of palindromic DNA sequence is directly and reversibly controlled by varying DeltaLk. Indeed the branch point behaves as a nanomechanical gear that links rotation with translation, a feature related to the helicity of DNA. We obtain experimentally a very good linear relationship between the extension of the molecule and DeltaLk. We use then this experiment to obtain a precise measurement of the pitch of B-DNA in solution: 3.61 +/- 0.03 nm/turn.     

Zhang's conjecture and squares of Abelian surfaces

We give in this Note some squares of Abelian surfaces that are counterexamples to a conjecture formulated by Zhang about the intersection of subvarieties and preperiodic points.