Materials Literature
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A heterogeneous 1D dynamic model of SCR−de-NO x (SCR = selective catalytic reduction) monolith reactors is developed, based on the concept of the “active” catalyst region. Its predictions are practically equivalent to those of a previous 2D model, but its numerical solution is faster by 1 order of magnitude, making it…
We have investigated the ordering dynamics and mechanism of a nearly symmetric polystyrene- block -polyisoprene by quenching the specimen from a temperature above the order−disorder transition temperature, T ODT, to temperatures below T ODT, by using time-resolved small-angle X-ray scattering (SAXS) and transmission e…
We demonstrate the relation between supercooling of n -alkane melts and the appearance or nonappearance of rotator phases. Supercooling occurs for the shorter, even chain lengths. The lack of supercooling in most n -alkane melts is discussed in terms of surface crystallization. We argue that melt crystallization of th…
Future developments in circuit design and magnetic data storage will demand smaller and smaller structures. In his Research Commentary, Fasol reviews recent methods for fabricating metallic and magnetic nanowires. In some cases, the precision of existing technology can be applied to creating tiny wires with useful pro…
We discuss a self-avoiding walk model of the adsorption of a copolymer at a plane surface, where the copolymer contains two types of monomers. We concentrate on the case where one type of monomer ( A ) has a short-range interaction with the surface and the other ( B ) has no interaction with the surface. We show that…
An approach based on He scattering is used to develop an atomic-level structural model for an epitaxially grown disordered sub-monolayer of Ag on Pt(111) at 38K. Quantum scattering calculations are used to fit structural models to the measured angular intensity distribution of He atoms scattered from this system. The…
We study experimentally the molecular weight $M$ dependence of spreading rates of molecularly thin precursor films, growing at the bottom of droplets of polymer liquids. In accord with previous observations, we find that the radial extension R(t) of the film grows with time as R(t) = (D_{exp} t)^{1/2}. Our data substa…
We have used scanning probe microscopy to investigate self-assembled monolayers of chemically synthesized peptides. We find that the peptides form a dense uniform monolayer, above which is found a sparse additional layer. Using scanning tunneling microscopy, submolecular resolution can be obtained, revealing the alpha…
We study the behavior of a monolayer, which occupies initially a bounded region on an ideal crystalline surface and then evolves in time due to random hopping motion of the monolayer particles. In the case when the initially occupied region is the half-plane $X \leq 0$, we determine explicitly, in terms of an analytic…
It was demonstrated that polymeric supramolecular nanostructures with several length scales allow straightforward tailoring of hierarchical order-disorder and order-order transitions and the concurrent switching of functional properties. Poly(4-vinyl pyridine) (P4VP) was stoichiometrically protonated with methane sulf…
Human angiogenin (Ang), a homologue of bovine pancreatic ribonuclease A (RNase A), is a potent inducer of blood vessel formation. It exerts a ribonucleolytic activity that is 10(5)-10(6)-fold lower than that of RNase A but nonetheless essential for biological action. Previous studies revealed some of the structural fe…
The cation radical salt of dimethylthiotetrathiafulvalene bisannulated tetraoxatetrathiatetracosane with linear pentaiodide and triiodide counterions was prepared by electrocrystallization. Within the crystal, linear I5- and I3- form a cage-like network, in which isolated cation radicals are located. The formation of…
Static and dynamic fluorescence from four α,ω-bis(1-pyrenyl)alkanes (P n P, where n, the number of carbons atoms in the alkane chain, is 3, 5, 7, and 12) has been examined in two polyethylene films of 31% (LDPE) and 71% (HDPE) crystallinity. Fluorescence decays of four P n P at ∼10 -5 M bulk concentrations, including…
Polymerization of hydrophilic monomers, such as acrylamide, in the aqueous lyotropic phases of counterion-coupled gemini surfactants (“cocogems”) results in highly ordered gels with a layerlike architecture between the submicrometer and micrometer length scale. The order of such gels is preserved even after removing t…
Three synthetic peptides corresponding to distinct segments of the subunit interface of the dimeric enzyme thymidylate synthase (residues 17-38, N 22; residues 174-190, M 17; and residues 201-220, C 20) have been investigated for their ability to function as inhibitors by modifying the quaternary structure of the enzy…
The crystal structure of the C82A mutant of barstar, the intracellular inhibitor of the Bacillus amyloliquefaciens ribonuclease barnase, has been solved to a resolution of 2.8 A. The molecule crystallizes in the space group I41 with a dimer in the asymmetric unit. An identical barstar dimer is also found in the crysta…
Cross-linked protein crystals (CLPCs) constitute a novel type of molecular sieves with high porosity. In order to characterize the fully hydrated CLPC, the method of macromolecular porosimetry was applied. This technique allows one to estimate the apparent pore sizes and pore size distribution in solid and soft hydrat…
On the basis of direct measurements by UV−vis spectroscopy, the dissociation constant of bichromate was found to decrease with temperature from 160 to 400 °C. For fixed Cr(VI) and KOH concentrations, the molal concentration of HCrO 4 - initially increases with temperature but decreases again in the vicinity of water's…
In situ XRD measurement of Mg/Al-layered double hydroxide at high temperature reveals that the hydrotalcite-like layered structure, which is stable at room temperature, thermally transforms to a metastable solid phase at 160−200 °C, depending atomic ratio Mg/Al of the layers. This metastable phase has smaller interlay…
The deep blue complex [Cp*(dippe)Fe(μ-C 4 )Fe(dippe)Cp*] 3+ [PF 6 ] - 3 ( 4 3+ [PF 6 ] - 3 ) was prepared by a cascade of three successive one-electron oxidations of the neutral complex Cp*(dippe)Fe(μ-C 4 )Fe(dippe)Cp* ( 4 ). This unprecedented trication was characterized by X-ray methods, and its triradical structure…