Materials Literature
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Designed coiled-coil heterotrimers are described whose assembly is governed by both hydrophobic and hydrophilic forces. Sterically matched hydrophobic core side-chain packing of alanine and cyclohexylalanine has been shown to promote formation of a 1:1:1 heterotrimer. Manipulation of hydrophilic glutamic acid (Glu)/ly…
The adsorption and intercalation of the cationic luminescence probe, tris(2,2‘-bipyridine)ruthenium(II) complex ([Ru(bpy) 3 ] 2+ or Rubpy), into hectorite and Laponite host clay films were investigated. Because the photophysical properties of Rubpy are strongly influenced by the lamellar nanospace of the smectite host…
The electric conductance of the graphite ribbon with locally applied gate voltage has been studied in terms of the Landauer approach. In the low-energy region, nano-graphite ribbon with zigzag boundaries exhibits the single electronic transport channel due to the edge states. The chemical potential dependence of the e…
A new synthesis procedure has been developed for a series of maleimide-based fluorophores, exhibiting a large variation of emission spectra spanning the entire visible range.
The information depth (ID) is a measure of the sampling depth for the detected signal in Auger-electron spectroscopy (AES) and x-ray photoelectron spectroscopy (XPS) while the mean escape depth (MED) is a measure of surface sensitivity. We report ID and MED calculations for Si 2s, Si 2p3/2, Cu 2s, Cu 2p3/2, Au 4s, and…
The proper assignment of metal ions in X-ray structures of proteins is not always easy, but in many cases this knowledge can be important, e.g. for an understanding of enzyme mechanism. In this publication, the bond-valence approach is assessed critically. A simplified version, the calcium bond-valence sum (CBVS), is…
Abstract Propagation in the cationic ring‐opening polymerization of cyclic ethers involves nucleophilic attack of oxygen atoms from the monomer molecules on the cationic growing species (oxonium ions). Such a mechanism is known as the active chain‐end mechanism. If hydroxyl groups containing compounds are present in t…
Mesoporous silicas of the MSU-X type, made with nonionic polyethylenoxide-based (PEO) surfactants, were synthesized according to a two-step process that gives intermediary stable hybrid micelles. The influence of the various synthesis parameters, such as the silica concentration, the addition of a swelling agent (TMB:…
Percolation of particle arrays is of high interest in microstructural design of materials. While there have been numerous contributions to theoretical modeling of percolation in particulate systems, no analytical approximation for the generalized problem of variable aspect-ratio ellipses has been reported. In the pres…
A nonlinear thermodynamic theory is used to describe the influence of an external mechanical loading on the ferroelectric, dielectric, and piezoelectric properties of epitaxial thin films grown on dissimilar cubic substrates. The calculations are performed for single-domain perovskite films in the approximation of a h…
An algorithm is described for automated building of side chains in an electron-density map once a main-chain model is built and for alignment of the protein sequence to the map. The procedure is based on a comparison of electron density at the expected side-chain positions with electron-density templates. The template…
We show here that field emission (FE) can be used to directly observe the vibration resonances nu(R) of carbon nanotubes (CNTs) and that the tension created by the applied field allows the tuning of these resonances by up to a factor of 10. The resonances are observable by the changes they create in the FE pattern or…
The interaction of atomic hydrogen and low-energy hydrogen ions with ${\mathrm{sp}}^{2}$-bonded carbon is investigated on the surfaces of ${\mathrm{C}}_{60}$ multilayer films, single-walled carbon nanotubes, and graphite (0001). These three materials have been chosen to represent ${\mathrm{sp}}^{2}$-bonded carbon netw…
Two crystal structures of dehydrated <TEX>$Ag^+-andTl^+$</TEX>-exchanged zeolite X<TEX>$Ag_{27}Tl_{65-}X\;and\;Ag_{23}Tl_{69-}X$</TEX>have been determined by single-crystal X-ray diffraction techniques in the cubic space group Fd3 at 21(1) <TEX>$^{\circ}C(a=24.758(4)\AAa=24.947(4)$</TEX>, <TEX>${\AA}respectively).$</T…
A theoretical analysis of the ground state of long-chain (K@C$_{60}$)$_n$ is presented. Within mean field theory, a ferroelectric ground state is found to be stable because of the pseudo-Jahn-Teller mixing of the b$_{1u}$ and the b$_{2g}$ band with a zone-center optical phonon involving the displacement of the endohed…
The recently derived sum rules for the scattering phase shifts of the Overhauser geminals (being 2-body-wave functions which parametrize the pair density together with an appropriately chosen occupancy) are generalized to integral equations which allow in principle to calculate the momentum distribution, supposed the…
Diffusing wave spectroscopy has been used to investigate the thermally driven displacement of colloidal particles dispersed in solutions of associating polymers (APs). The effect of varying colloidal probe size on the measured particle displacements is studied in particular. Recent theories of microrheology are examin…
UV−visible spectra have been studied for a series of p-substituted tetraphenylporphyrins (TPPs) titrated with strong acid in various solvents. Substituent effects on the Soret and Q ( I ) absorption peaks and the fluorescence emission peaks have been treated by Hammett correlations. In general, there are only small ef…
Aggregates of the diacid form of tetra(p-carboxyphenyl)porphyrin (TCPP) are found to be stabilized in aqueous solution at low pH in the presence of poly(vinyl alcohol). At pH values in the range from about 1 to 4, a split Soret band is observed which is independent of counterion and tentatively assigned to a dimer spe…
Heteroepitaxial strain can be a controlling factor in the lateral dimensions of 1-D nanostructures. Bi nanolines on Si(001) have an atomic structure which involves a large sub-surface reconstruction, resulting in a strong elastic coupling to the surrounding silicon. We present variable-bias STM and first principles el…